JP7591378B2 - Control valve - Google Patents

Description

The present invention relates to a control valve.

For example, construction machinery such as hydraulic excavators are driven by various actuators. The actuators are driven by hydraulic oil (fluid) discharged from a pump (hydraulic pump). The actuators are controlled by a fluid system that adjusts the flow rate of the hydraulic oil. The fluid system includes, for example, a control valve with a spool. The control valve can adjust the width (shape) of the flow path through which the hydraulic oil flows by moving the spool. This adjusts the flow rate of the hydraulic oil supplied to the actuator.

Japanese Patent Application Publication No. 6-193604

However, with control valves and fluid systems such as those described above in the conventional technology, it can be difficult to highly adjust the flow rate of hydraulic oil supplied to the actuator in accordance with the operation of the construction machine.

The present invention provides a control valve capable of highly regulating the flow rate of a fluid supplied to an actuator.

A control valve according to one aspect of the present invention includes a first meter-in spool having a first meter-in passage leading to a first pump, a second meter-in spool having a second meter-in passage leading to a second pump, and a supply passage leading to the first meter-in passage and the second meter-in passage and leading to a supply/discharge port of an actuator.

With this configuration, the first meter-in spool is driven and controlled to pass the first pump through the first meter-in flow path. Also, the second meter-in spool is driven and controlled to pass the second pump through the second meter-in flow path. This makes it possible, for example, to adjust the amount of fluid discharged by the first pump from 0 to 100%, adjust the amount of fluid discharged by the second pump from 0 to 100%, and then merge the fluid discharged from at least one of the first pump and the second pump in the supply flow path. As a result, the ratio of fluid supplied to the actuator from the first pump and the second pump can be freely changed within a range twice the discharge amount of each pump. This allows the flow rate of fluid supplied to the actuator to be adjusted with high performance.

The above configuration may include a meter-in spool housing that houses the first meter-in spool and the second meter-in spool together.

In the above configuration, the meter-in spool housing may have an intermediate portion that is disposed between the first meter-in spool and the second meter-in spool and that faces each other in the axial direction of the meter-in spool and that leads to a tank.

The above configuration may include a meter-out spool having a flow path that leads to the supply flow path and the supply/discharge port of the actuator.

In the above configuration, the first meter-in spool may have a recess that connects the supply flow path to the supply/discharge port of the actuator, or connects the supply/discharge port of the actuator to a tank.

In the above configuration, the second meter-in spool may have another recess that connects the supply passage to the supply/discharge port of the actuator, or connects the supply/discharge port of the actuator to a tank.

The above configuration may include a block body that collectively accommodates the first meter-in spool, the second meter-in spool, and the meter-out spool.

A control valve according to another aspect of the present invention includes a first meter-in spool having a first meter-in passage leading to a first pump, a second meter-in spool having a second meter-in passage leading to a second pump, a supply passage leading to the first meter-in passage and the second meter-in passage and leading to a supply/discharge port of an actuator, and a meter-out spool having a passage leading to the supply passage and the supply/discharge port of the actuator, a block body that collectively houses the first meter-in spool, the second meter-in spool, and the meter-out spool, and a meter-in spool housing portion that is provided in the block body and collectively houses the first meter-in spool and the second meter-in spool, and has an intermediate portion that leads to a tank between the first meter-in spool and the second meter-in spool that face each other in the axial direction of each meter-in spool.

With this configuration, the first meter-in spool is driven and controlled to pass the first pump through the first meter-in flow path. Also, the second meter-in spool is driven and controlled to pass the second pump through the second meter-in flow path. This allows, for example, the amount of fluid discharged by the first pump to be adjusted between 0 and 100%, and the amount of fluid discharged by the second pump to be adjusted between 0 and 100%, so that the fluid discharged from at least one of the first pump and the second pump can be merged in the supply flow path. As a result, the ratio of fluid supplied to the actuator from the first pump and the second pump can be freely changed within a range twice the discharge amount of each pump. This allows the flow rate of fluid supplied to the actuator to be adjusted with high performance.

The flow path of the meter-out spool is connected to the supply flow path and also to the supply/discharge port of the actuator. Here, the supply flow path is connected to the first meter-in flow path of the first meter-in spool and the second meter-in flow path of the second meter-in spool. Therefore, the meter-out spool can be commonly used for both the first meter-in spool and the second meter-in spool. This allows the number of meter-out spools to be reduced to one, simplifying the configuration of the control valve.

In addition, the first meter-in spool, second meter-in spool, and meter-out spool are all housed together in a block body. This allows the number of blocks to be reduced, simplifying the control valve and making it more compact.

In addition, the two spools, the first meter-in spool and the second meter-in spool, are accommodated together in a meter-in spool accommodation section, which makes it possible to reduce the number of meter-in spool accommodation sections and simplify the structure of the control valve.
In addition, an intermediate portion is formed between the first meter-in spool and the second meter-in spool in the meter-in spool housing portion, which are opposed to each other in the axial direction. The tank is connected to this intermediate portion. Therefore, for example, when the first meter-in spool and the second meter-in spool are moved so that the volume of the intermediate portion becomes smaller, the fluid in the intermediate portion can be discharged to the tank. As a result, it is possible to prevent the pressure of the fluid in the intermediate portion from increasing, making it difficult for each meter-in spool to move. Therefore, the first meter-in spool and the second meter-in spool can be moved smoothly inside the meter-in spool housing portion.

A control valve according to another aspect of the present invention includes a first meter-in spool having a first meter-in flow path leading to a first pump, a second meter-in spool having a second meter-in flow path leading to a second pump, a supply flow path leading to the first meter-in flow path and the second meter-in flow path and leading to a supply/discharge port of an actuator, and a meter-out spool having a flow path leading to the supply flow path and the supply/discharge port of the actuator, a block body that collectively holds the first meter-in spool, the second meter-in spool, and the meter-out spool, and a valve that is provided in the block body and holds the first meter-in spool and and a meter-in spool housing section that houses the first meter-in spool and the second meter-in spool together and has an intermediate section that communicates with a tank between the first meter-in spool and the second meter-in spool that face each other in the axial direction of the meter-in spools, the first meter-in spool has a recess that connects the supply flow path to the supply/discharge port of the actuator or connects the supply/discharge port of the actuator to a tank, and the second meter-in spool has another recess that connects the supply flow path to the supply/discharge port of the actuator or connects the supply/discharge port of the actuator to a tank.

With this configuration, the first meter-in spool is driven and controlled to pass the first pump through the first meter-in flow path. Also, the second meter-in spool is driven and controlled to pass the second pump through the second meter-in flow path. This allows, for example, the amount of fluid discharged by the first pump to be adjusted between 0 and 100%, and the amount of fluid discharged by the second pump to be adjusted between 0 and 100%, so that the fluid discharged from at least one of the first pump and the second pump can be merged in the supply flow path. As a result, the ratio of fluid supplied to the actuator from the first pump and the second pump can be freely changed within a range twice the discharge amount of each pump. This allows the flow rate of fluid supplied to the actuator to be adjusted with high performance.

The flow path of the meter-out spool is connected to the supply flow path and also to the supply/discharge port of the actuator. Here, the supply flow path is connected to the first meter-in flow path of the first meter-in spool and the second meter-in flow path of the second meter-in spool. Therefore, the meter-out spool can be commonly used for both the first meter-in spool and the second meter-in spool. This allows the number of meter-out spools to be reduced to one, simplifying the configuration of the control valve.

In addition, the first meter-in spool, second meter-in spool, and meter-out spool are all housed together in a block body. This allows the number of blocks to be reduced, simplifying the control valve and making it more compact.

In addition, the two spools, the first meter-in spool and the second meter-in spool, are accommodated together in a meter-in spool accommodation section, which makes it possible to reduce the number of meter-in spool accommodation sections and simplify the structure of the control valve.
In addition, an intermediate portion is formed between the first meter-in spool and the second meter-in spool in the meter-in spool housing portion, which are opposed to each other in the axial direction. The tank is connected to this intermediate portion. Therefore, for example, when the first meter-in spool and the second meter-in spool are moved so that the volume of the intermediate portion becomes smaller, the fluid in the intermediate portion can be discharged to the tank. As a result, it is possible to prevent the pressure of the fluid in the intermediate portion from increasing, making it difficult for each meter-in spool to move. Therefore, the first meter-in spool and the second meter-in spool can be moved smoothly inside the meter-in spool housing portion.

Furthermore, the first meter-in spool has a recess between the supply passage and the supply/discharge port of the actuator, so that the supply passage can be connected to the supply/discharge port of the actuator via the recess, thereby reducing pressure loss of the fluid supplied from the supply passage to the actuator.
In addition, a recess is provided between the supply/discharge port of the actuator and the tank, so that the actuator can be connected to the tank via the recess, thereby increasing the flow rate of the fluid returning from the actuator to the tank.

In addition, the second meter-in spool has another recess between the supply/discharge port of the actuator and the tank, so that the actuator can be connected to the tank via the other recess, thereby increasing the flow rate of the fluid returning from the actuator to the tank.
Furthermore, another recess is interposed between the supply flow path and the supply/discharge port of the actuator. This allows the supply flow path to communicate with the actuator via the other recess. This reduces the pressure loss of the fluid supplied from the supply flow path to the actuator.

A fluid system according to another aspect of the present invention includes a first pump and a second pump, an actuator driven by fluid discharged from the first pump and the second pump, and a control valve provided between the first pump and the second pump and the actuator to adjust the flow rate of the fluid supplied to the actuator or the flow rate of the fluid discharged from the actuator, the control valve including a first meter-in spool having a first meter-in flow path leading to the first pump, a second meter-in spool having a second meter-in flow path leading to the second pump, a supply flow path leading to the first meter-in flow path and the second meter-in flow path and leading to a supply/discharge port of the actuator, and a meter-out spool having a flow path leading to the supply flow path and the supply/discharge port of the actuator.

By configuring such a fluid system, the first meter-in spool is driven and controlled to pass the first pump through the first meter-in flow path. Also, the second meter-in spool is driven and controlled to pass the second pump through the second meter-in flow path. This allows, for example, the amount of fluid discharged by the first pump to be adjusted from 0 to 100%, and the amount of fluid discharged by the second pump to be adjusted from 0 to 100%, so that the fluid discharged from at least one of the first pump and the second pump can be merged in the supply flow path. As a result, the ratio of fluid supplied to the actuator from the first pump and the second pump can be freely changed within a range of twice the discharge amount of each pump. Therefore, the flow rate of fluid supplied to the actuator can be adjusted with high performance.

A construction machine according to another aspect of the present invention includes a fluid system and a vehicle body on which the fluid system is mounted and driven and controlled by the fluid system. The fluid system includes a first pump and a second pump, an actuator driven by the fluid discharged from the first pump and the second pump to operate the vehicle body, and a control valve provided between the first pump and the second pump and the actuator to adjust the flow rate of the fluid supplied to the actuator or the flow rate of the fluid discharged from the actuator. The control valve includes a first meter-in spool having a first meter-in flow path leading to the first pump, a second meter-in spool having a second meter-in flow path leading to the second pump, a supply flow path leading to the first meter-in flow path and the second meter-in flow path and leading to a supply/discharge port of the actuator, and a meter-out spool having a flow path leading to the supply flow path and the supply/discharge port of the actuator.

This configuration allows for highly accurate drive control of construction machinery.

An actuator drive control method according to another aspect of the present invention includes a flow rate adjustment step of adjusting the combined flow rate of fluids discharged from two pumps that are respectively connected to the meter-in spools by controlling the drive of the two meter-in spools, and a fluid supply step of supplying the fluid whose combined flow rate has been adjusted by the flow rate adjustment step to an actuator, thereby driving the actuator.

By using this control method, the flow rate of the fluid supplied to the actuator can be adjusted with high accuracy. This allows the actuator drive control to be performed with high precision.

The present invention allows for highly accurate adjustment of the flow rate of fluid supplied to the actuator.

1 is a schematic diagram of a construction machine according to a first embodiment of the present invention. 1 is a schematic diagram of a hydraulic system according to a first embodiment of the present invention; 5A and 5B are diagrams illustrating an example of an operation of the hydraulic system when the first meter-in spool and the second meter-in spool are located in a first neutral position and a second neutral position in the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing an example of an operation when raising a boom with the hydraulic system in the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing an example of an operation when lowering a boom with the hydraulic system in the first embodiment of the present invention. FIG. 11 is an explanatory diagram showing an example of a hydraulic system when a boom is held stationary by an independent metering valve in a second embodiment of the present invention. FIG. 11 is an explanatory diagram showing an example of an operation when raising a boom with the hydraulic system in the second embodiment of the present invention. FIG. 11 is an explanatory diagram showing an example of an operation when lowering a boom with the hydraulic system in the second embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of a hydraulic system when the boom is held stationary by the independent metering valve in the third embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of an operation when raising a boom with the hydraulic system in the third embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of a hydraulic system when an arm is held stationary by an independent metering valve in a fourth embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of an operation when an arm is pushed by the hydraulic system in the fourth embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of a hydraulic system when an arm is held stationary by an independent metering valve in a fifth embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of movement when an arm is pulled by a hydraulic system in a fifth embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of excavation when an arm is pulled with an independent metering valve in a fifth embodiment of the present invention. FIG. 13 is an explanatory diagram showing an example of an operation when an arm is pushed by the hydraulic system in the fifth embodiment of the present invention.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following embodiment, a hydraulic excavator equipped with a hydraulic system will be used as an example of construction machinery. In the drawings used in the following description, the scale of each component has been appropriately altered to ensure that each component is of a recognizable size.

[First embodiment]
<Construction machinery>
FIG. 1 is a schematic diagram of a construction machine 100 according to a first embodiment.
1, the construction machine 100 is, for example, a hydraulic excavator. The construction machine 100 includes a rotating body (an example of a vehicle body in the claims) 101, a running body (an example of a vehicle body in the claims) 102, and a hydraulic system 109 that is mounted on the rotating body 101 and the running body 102 and controls the drive of the rotating body and the running body 102.
The rotating body 101 is provided rotatably on a running body 102. The rotating body 101 is equipped with a hydraulic pump 110 and a hydraulic control device 1 that controls the flow rate of hydraulic oil (an example of a fluid in the claims) discharged from the hydraulic pump 110.

The rotating body 101 includes a cab 103 on which an operator can ride, a boom 104 whose one end is connected to the rotating body 101 so as to be freely swingable, an arm 105 whose one end is connected to the other end (tip) of the boom 104 opposite the rotating body 101 so as to be freely swingable, a bucket 106 whose other end (tip) of the arm 105 opposite the boom 104 so as to be freely swingable, and an operating unit 107 provided on the cab 103. The running body 102, the rotating body 101, the boom 104, the arm 105, and the bucket 106 are driven by various hydraulic actuators 111. The hydraulic actuators 111 are working equipment units of the construction machine 100 that are driven by hydraulic oil from a hydraulic pump 110 supplied via the hydraulic control device 1.

<Hydraulic system>
Fig. 2 is a schematic diagram of the hydraulic system 109 of the first embodiment. Fig. 2 is a schematic diagram including a cross section of the hydraulic control device 1. Fig. 2 shows a state in which the first meter-in spool 5 and the second meter-in spool 6 of the first embodiment are positioned in the first neutral position and the second neutral position, respectively. Also, Fig. 2 shows a state in which the meter-out spool 15 of the first embodiment is positioned in the center position.

As shown in FIG. 2, a hydraulic system (an example of a fluid system in the claims) 109 includes a hydraulic control device 1, a hydraulic pump 110 that supplies hydraulic oil to the hydraulic control device 1, and a hydraulic actuator (an example of an actuator in the claims) 111 that is driven and controlled by the hydraulic control device 1. Note that in FIG. 2 and subsequent figures, in order to simplify the explanation of directions, one or one end will be described as pointing to the right in the figure, and the other or the other end will be described as pointing to the left in the figure. In each figure, one and the other are indicated by arrows.

The hydraulic actuator 111 is composed of, for example, a hydraulic motor 112 for moving the running body 102 and rotating the rotating body 101, and various hydraulic cylinders (an example of the actuator in the claims) 113 for driving the boom 104, the arm 105, and the bucket 106 (see FIG. 1).
Hereinafter, one hydraulic cylinder 113 will be described as a representative example among various hydraulic cylinders 113. The representative hydraulic cylinder 113 is a boom driving cylinder that drives the boom 104 selected from the boom 104, the arm 105, and the bucket 106.

The hydraulic cylinder 113 has a cylinder 114, a piston rod 115 that is freely slidable within the cylinder 114, a head port Hp (an example of a supply and discharge port in the claims) and a rod port Rp (an example of a supply and discharge port in the claims) provided in the cylinder 114.
The head port Hp is provided in a portion 114a on the cylinder head side of the cylinder 114. The rod port Rp is provided in a portion 114b on the piston rod 115 side of the cylinder 114.

The hydraulic pump 110 is driven, for example, by a prime mover (not shown). The hydraulic pump 110 varies the amount of hydraulic oil discharged based on an operation signal from an operation unit 107 provided in the cab 103 (see FIG. 1). The hydraulic control device 1 is also driven and controlled based on the operation signal from the operation unit 107 (see FIG. 1).

There are two hydraulic pumps 110. Hereinafter, one of the two hydraulic pumps 110 will be referred to as a "first pump 110A." Additionally, the other of the two hydraulic pumps 110 will be referred to as a "second pump 110B."
The first pump 110A is, for example, a variable displacement pump whose hydraulic oil discharge amount per rotation can be adjusted in the range of 0 to 100%. The second pump 110B is, for example, a variable displacement pump whose hydraulic oil discharge amount per rotation can be adjusted in the range of 0 to 100% like the first pump 110A. The first pump 110A and the second pump 110B have, for example, the same pump capacity.

<Hydraulic control device>
The hydraulic control device 1 includes various IMVs (Independent Metering Valves) 2 (hereinafter also referred to as “independent metering valves”). The various independent metering valves (an example of a control valve in the claims) 2 control various hydraulic cylinders 113 that drive the boom 104, the arm 105, and the bucket 106.
The independent metering valve 2 for the boom 104 will be described below as a representative example among various independent metering valves 2. The representative independent metering valve 2 is a valve that controls the hydraulic cylinder 113 that drives the boom 104 selected from the boom 104, the arm 105, and the bucket 106.

<Independent Metering Valve (IMV)>
The independent metering valve 2 mainly comprises a valve body (an example of a block body in the claims) 3, a round-rod-shaped first meter-in spool 5 housed in the valve body 3, a first meter-in solenoid proportional valve 7 that drives and controls the first meter-in spool 5, a round-rod-shaped second meter-in spool 6 housed in the valve body 3, and a second meter-in solenoid proportional valve 8 that drives and controls the second meter-in spool 6. That is, the independent metering valve 2 comprises two independent meter-in spools, the first meter-in spool 5 and the second meter-in spool 6.

Moreover, the independent metering valve 2 mainly comprises a round rod-shaped meter-out spool 15 housed in the valve body 3, and a first meter-out solenoid proportional valve 16 and a second meter-out solenoid proportional valve 17 which drive and control the meter-out spool 15.
Furthermore, the independent metering valve 2 is provided with a control unit 25 that controls the solenoid proportional valves 7 , 8 , 16 , and 17 .

The control unit 25 is realized by a processor such as a CPU (Central Processing Unit) executing a program stored in a program memory. The control unit 25 may be realized by hardware such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array), or may be realized by software and hardware working together.

The valve body 3 has a first spool hole (an example of a meter-in spool accommodating portion in the claims) 10 that accommodates a first meter-in spool 5 and a second meter-in spool 6, a first pump port P1, a second pump port P2, a first supply port S1, and a second supply port S2 that open into the first spool hole 10, a second spool hole 20 that accommodates the meter-out spool 15, and a first tank port T1, a second tank port T2, a first drain port D1, and a second drain port D2 that open into the second spool hole 20.
That is, the first meter-in spool 5 , the second meter-in spool 6 , and the meter-out spool 15 are commonly provided in one valve body 3 .

The valve body 3 also has a bridge flow passage (an example of a supply flow passage in the claims) 30 whose cross section along one direction of the valve body 3 (i.e., the axial direction of the first meter-in spool 5, the second meter-in spool 6, and the meter-out spool 15; hereinafter, this axial direction may be simply referred to as the axial direction) is U-shaped, a first rod flow passage 31 located on one side of the bridge flow passage 30, a second rod flow passage 32 leading to the first rod flow passage 31, a first head flow passage 33 located on the other side of the bridge flow passage 30, a second head flow passage 34 leading to the first head flow passage 33, a first tank flow passage 35 located on the side of the first rod flow passage 31, a second tank flow passage 36 located on the side of the second head flow passage 34, and a bypass flow passage 37 whose cross section along the axial direction is U-shaped.

The first spool hole 10 and the second spool hole 20 are formed along one direction of the valve body 3. The first spool hole 10 and the second spool hole 20 have a circular cross section along the axial direction. The first spool hole 10 and the second spool hole 20 are formed in parallel, spaced apart from each other, for example, in a direction perpendicular to the longitudinal direction (i.e., the axial direction) of each spool hole 10, 20.

The first meter-in spool 5 and the second meter-in spool 6 are housed together in one of the first spool holes 10. The first spool hole 10 also has an intermediate section 13 in the center in the axial direction. The intermediate section 13 is a chamber formed between the first meter-in spool 5 and the second meter-in spool 6 that face each other. The intermediate section 13 is connected to the tank 120 via the third discharge flow path 137 (see FIG. 3).

The first pump port P1 is connected to the first pump 110A via the first supply flow path 131. The second pump port P2 is connected to the second pump 110B via the second supply flow path 132. The first supply port S1 is connected to the bridge flow path 30 via the first check valve 41. The second supply port S2 is connected to the bridge flow path 30 via the second check valve 42. Note that "connected" (or "connected" as described below) means that hydraulic oil (i.e., fluid) is allowed to flow. For example, "The first pump port P1 is connected to the first pump 110A via the first supply flow path 131" means that the first pump port P1 and the first pump 110A are connected via the first supply flow path 131 to allow hydraulic oil to flow.

The first tank port T1 is connected to the tank 120 via the first discharge flow path 135. The second tank port T2 is connected to the tank 120 via the second discharge flow path 136. The first discharge port D1 is connected to the rod port Rp via the rod flow paths 31, 32 and the rod side flow path 133. The second discharge port D2 is connected to the head port Hp via the head flow paths 33, 34 and the head side flow path 134.

Both ends of the bridge passage 30 communicate with the first spool hole 10. The bridge passage 30 is disposed outwardly of the first supply port S1 and the second supply port S2 in the axial direction.
The first rod flow passage 31 is disposed between one end of the bridge flow passage 30 and the first tank flow passage 35 in the axial direction. The first rod flow passage 31 extends in a direction perpendicular to the axial direction. The first rod flow passage 31 communicates with the first tank flow passage 35 via a first relief valve 45 for releasing excessive high pressure.
The second rod flow path 32 is disposed between the first spool hole 10 and the second spool hole 20. The second rod flow path 32 is disposed on an extension line of the first rod flow path 31.

The first head flow path 33 is disposed between the other end of the bridge flow path 30 and the second tank flow path 36 in the axial direction. The first head flow path 33 extends in a direction intersecting the axial direction. The first head flow path 33 communicates with the second tank flow path 36 via a second relief valve 46 for releasing excessive high pressure. The first head flow path 33 is provided with a lock valve 47 (a retention valve for preventing the boom 104 from lowering due to inertia) for reducing leakage.
The second head flow passage 34 is disposed between the first spool hole 10 and the second spool hole 20. The second head flow passage 34 extends in a direction perpendicular to the axial direction.

The first tank flow passage 35 extends in a direction perpendicular to the axial direction outside the first rod flow passage 31. The second tank flow passage 36 extends in a direction perpendicular to the axial direction outside the first head flow passage 33. Both ends of the bypass flow passage 37 communicate with the second spool hole 20. The bypass flow passage 37 communicates with the bypass port G1 via the third check valve 43.

A first positioning mechanism 50 is provided at one axial end of the valve body 3. The first positioning mechanism 50 includes a first casing 51 attached to one axial end of the valve body 3 so as to close one end of each of the first spool hole 10 and the second spool hole 20. The first casing 51 has a first storage chamber 53 connected to one end of the first spool hole 10 and housing a first coil spring 52, and a second storage chamber 55 connected to one end of the second spool hole 20 and housing a second coil spring 54. The first casing 51 also has a first pump flow passage 56 extending in a direction perpendicular to the axial direction outside the first storage chamber 53 and the second storage chamber 55, and a first drain flow passage 57 extending in a direction perpendicular to the axial direction outside the first pump flow passage 56.

A second positioning mechanism 60 is provided at the other axial end of the valve body 3. The second positioning mechanism 60 includes a second casing 61 attached to the other axial end of the valve body 3 so as to close the other ends of the first spool hole 10 and the second spool hole 20. The second casing 61 has a third storage chamber 63 connected to the other end of the first spool hole 10 and housing a third coil spring 62, and a fourth storage chamber 65 connected to the other end of the second spool hole 20 as a space through which hydraulic oil is guided. The second casing 61 also has a second pump flow passage 66 extending in a direction perpendicular to the axial direction outside the third storage chamber 63 and the fourth storage chamber 65, and a second drain flow passage 67 extending in a direction perpendicular to the axial direction outside the second pump flow passage 66.

A first meter-in spool 5 is housed so as to be slidable in the axial direction on one side of the first spool hole 10 of the valve body 3. The first meter-in spool 5 is housed so as to be positioned at a first neutral position (position shown in FIG. 2), a first supply position (position shown in FIG. 4), and an arbitrary supply position between the first neutral position and the first supply position.
The first neutral position is a position where the intermediate portion 13 is most widely expanded in the axial direction and the first meter-in spool 5 is disposed on one side of the intermediate portion 13. The first supply position is a position where the intermediate portion 13 is most narrowed in the axial direction and the first meter-in spool 5 is disposed on one side of the intermediate portion 13. The first supply position is a full stroke position of the first meter-in spool 5 where the first pump 110A is connected to the bridge flow passage 30 and the hydraulic oil discharged from the first pump 110A is supplied to the bridge flow passage 30.

The second meter-in spool 6 is accommodated in the other side of the first spool hole 10 of the valve body 3 so as to be freely slidable in the axial direction. The second meter-in spool 6 is accommodated so as to be positioned at a second neutral position (position shown in FIG. 2), a second supply position (position shown in FIG. 4), and any supply position between the second neutral position and the second supply position.

The second neutral position is a position where the intermediate portion 13 is most widely expanded in the axial direction, and the second meter-in spool 6 is disposed on the other side of the intermediate portion 13. The second supply position is a position where the intermediate portion 13 is most narrowed in the axial direction, and the second meter-in spool 6 is disposed on the other side of the intermediate portion 13. The second supply position is a full stroke position of the second meter-in spool 6 where the second pump 110B is connected to the bridge flow passage 30, and the hydraulic oil discharged from the second pump 110B is supplied to the bridge flow passage 30.
The first spool hole 10, the first meter-in spool 5, the second meter-in spool 6, etc. constitute the meter-in valve 4.

The first meter-in spool 5 has, for example, a first recess 5a formed in an annular shape, and a plurality of first lands 5b formed on both axial sides (one side and the other side) of the first recess 5a. The first meter-in spool 5 can block the flow path and adjust the flow rate by the first recess 5a, the first lands 5b, etc. The first meter-in spool 5 also has a first meter-in flow path 11 formed, for example, by the first recess 5a, etc.

The second meter-in spool 6 has, for example, a second recess 6a formed in an annular shape, and a plurality of second lands 6b formed on both axial sides (one side and the other side) of the second recess 6a. The second meter-in spool 6 can block the flow path and adjust the flow rate by the second recess 6a, the second lands 6b, etc. The second meter-in spool 6 also has a second meter-in flow path 12 formed, for example, by the second recess 6a, etc.

FIG. 3 is an explanatory diagram of an example of the operation of the hydraulic system 109 when the first meter-in spool 5 and the second meter-in spool 6 of the first embodiment are located in the first neutral position and the second neutral position.
3, when the first meter-in spool 5 is disposed in the first neutral position, it closes, for example, the first pump port P1 and the first supply port S1 by the first land 5b etc. When the second meter-in spool 6 is disposed in the second neutral position, it closes, for example, the second pump port P2 and the second supply port S2 by the second land 6b etc.

4 is an explanatory diagram showing an example of an operation when the boom 104 (see FIG. 1) is raised by the hydraulic system 109 of the first embodiment. FIG. 4 corresponds to an explanatory diagram of the action of pushing out the piston rod 115 of the hydraulic cylinder 113.
4, when the first meter-in spool 5 is disposed in the first supply position, it communicates between the first pump port P1 and the first supply port S1 through the first meter-in flow path 11. When the second meter-in spool 6 is disposed in the second supply position, it communicates between the second pump port P2 and the second supply port S2 through the second meter-in flow path 12. As a result, the first pump port P1 and the second pump port P2 communicate with the bridge flow path 30 via the first supply port S1 and the second supply port S2, etc., respectively.
When the meter-out spool 15 described later is positioned in the second discharge position (the position shown in FIG. 5 ), the bridge passage 30 communicates with the rod port Rp via the first notched passage 21, the second rod passage 32, the first rod passage 31, etc. described later.

As shown in FIG. 2, a first meter-in solenoid proportional valve 7 is provided at one axial end of the first meter-in spool 5. A second meter-in solenoid proportional valve 8 is provided at the other axial end of the second meter-in spool 6. The first meter-in solenoid proportional valve 7 and the second meter-in solenoid proportional valve 8 are commonly used valves, and detailed explanations of their configurations will be omitted.

When the first meter-in solenoid proportional valve 7 is not energized, the first meter-in spool 5 is located in the first neutral position (the position shown in Figures 2 and 3). When the first meter-in solenoid proportional valve 7 is energized, the first meter-in spool 5 is driven based on an electrical signal and located in the first supply position (the position shown in Figures 4 and 5). Here, the first meter-in solenoid proportional valve 7 can steplessly control (adjust) the first meter-in spool 5 to any supply position within the range between the first neutral position and the first supply position according to (proportional to) the "current value" of the energized electrical signal.

When the second meter-in solenoid proportional valve 8 is not energized, the second meter-in spool 6 is positioned in the second neutral position (the position shown in Figures 2 and 3). When the second meter-in solenoid proportional valve 8 is energized, the second meter-in spool 6 is driven based on an electrical signal and positioned in the second supply position (the position shown in Figures 4 and 5). Here, the second meter-in solenoid proportional valve 8 can steplessly control (adjust) the second meter-in spool 6 to any supply position within the range between the second supply position and the second supply position according to (proportional to) the "current value" of the energized electrical signal.

The meter-out spool 15 is housed in the second spool hole 20 of the valve body 3 so as to be slidable in the axial direction. The meter-out spool 15 is housed so as to be positioned at three positions: a central position in the axial direction of the second spool hole 20 (positions shown in Figures 2 and 3), a position on one end side of the second spool hole 20 in the axial direction, and a position on the other end side of the second spool hole 20 in the axial direction.
Hereinafter, the position of one axial end of the second spool hole 20 will be referred to as a first discharge position (the position shown in FIG. 4), and the position of the other axial end of the second spool hole 20 will be referred to as a second discharge position (the position shown in FIG. 5).
The second spool hole 20 and the meter-out spool 15 constitute a meter-out valve 14 .

The meter-out spool 15 has, for example, a plurality of recesses 15a formed in an annular shape, a plurality of lands 15b formed between the recesses 15a, and a plurality of notches 15c formed in the lands 15b. The meter-out spool 15 can block the flow path and adjust the flow rate by using the recesses 15a, the lands 15b, the notches 15c, etc. The meter-out spool 15 also has, for example, a first notched flow path (an example of a flow path in the claims) 21 (see also FIG. 5) formed by the recesses 15a, etc., and a second notched flow path (an example of a flow path in the claims) 22 (see also FIG. 4) formed by the recesses 15a, etc.

FIG. 3 is a diagram illustrating an example of the operation of the hydraulic system 109 when the meter-out spool 15 of the first embodiment is located in the neutral position.
3, when the meter-out spool 15 is disposed at the central position, for example, the first tank port T1, the second tank port T2, the first drain port D1, the second drain port D2, etc. are blocked by the lands 15b etc. In other words, the central position is a neutral position in which the first tank port T1, the second tank port T2, the first drain port D1, the second drain port D2, etc. are blocked by the lands 15b etc.

As shown in FIG. 4, when the meter-out spool 15 is placed in the first discharge position, the first discharge port D1 and the first tank port T1 are connected by the first notched flow passage 21. As a result, the rod port Rp is connected to the first tank port T1 via the first notched flow passage 21, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, etc.

Furthermore, when the meter-out spool 15 is disposed in the first discharge position, the bridge passage 30 and the second discharge port D2 are communicated with each other through the second notched passage 22. Therefore, the bridge passage 30 is communicated with the head port Hp via the second notched passage 22, the second discharge port D2, the second head passage 34, the first head passage 33, and the like.
Furthermore, when the meter-out spool 15 is disposed in the first discharge position, the second tank port T2 is closed by the land 15b or the like.

5 is an explanatory diagram showing an example of an operation when the boom 104 (see FIG. 1) is lowered by the hydraulic system 109 of the first embodiment. FIG. 5 corresponds to an explanatory diagram of the action of retracting the piston rod 115 of the hydraulic cylinder 113.
5, when the meter-out spool 15 is disposed in the second discharge position, the second discharge port D2 and the second tank port T2 are communicated with each other through the second notched flow passage 22. As a result, the second tank port T2 is communicated with the head port Hp via the second notched flow passage 22, the second discharge port D2, the second head flow passage 34, the first head flow passage 33, and the like.

Furthermore, when the meter-out spool 15 is disposed in the second discharge position, the bridge passage 30 and the first discharge port D1 communicate with each other through the first notched passage 21. Therefore, the bridge passage 30 communicates with the rod port Rp via the first notched passage 21, the first discharge port D1, the second rod passage 32, the first rod passage 31, and the like.
Furthermore, when the meter-out spool 15 is disposed in the second discharge position, the first tank port T1 is blocked by the land 15b and the like.

The meter-out spool 15 is a spool for discharging the hydraulic oil inside the hydraulic cylinder 113 from the head port Hp and rod port Rp to the tank 120 via a tank port, etc. In addition, the meter-out spool 15 controls the amount of hydraulic oil discharged from the hydraulic cylinder 113 when discharging the hydraulic oil into the tank 120.

As shown in FIG. 2, a first meter-out solenoid proportional valve 16 is provided on one end of the meter-out spool 15. A second meter-out solenoid proportional valve 17 is provided on the other end of the meter-out spool 15. The first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17 are commonly used valves, like the first meter-in solenoid proportional valve 7 and the second meter-in solenoid proportional valve 8, and a detailed description of their configuration will be omitted.

The first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17 dispose the meter-out spool 15 at a central position when both the meter-out solenoid proportional valves 16, 17 are de-energized.
The first meter-out solenoid proportional valve 16 is energized while the second meter-out solenoid proportional valve 17 is in a non-energized state, thereby driving the meter-out spool 15 based on an electrical signal to place it in the second discharge position (the position shown in FIG. 5). Here, the first meter-out solenoid proportional valve 16 can steplessly control (adjust) the second discharge position according to (proportionally to) the "current value" of the energized electrical signal.

When the second meter-out solenoid proportional valve 17 is energized while the first meter-out solenoid proportional valve 16 is in a non-energized state, it drives the meter-out spool 15 based on an electrical signal to place it in the first discharge position (the position shown in FIG. 4). Here, the second meter-out solenoid proportional valve 17 can steplessly control (adjust) the second discharge position according to (proportionally to) the "current value" of the energized electrical signal.

<Method of controlling hydraulic actuator drive using independent metering valve and hydraulic system>
Next, a method of controlling the independent metering valve 2 and the hydraulic actuator 111 by the hydraulic system 109 will be described with reference to FIGS.
First, an example in which the boom 104 (see FIG. 1) of the construction machine 100 is held stationary by the independent metering valve 2 will be described with reference to FIGS.

2 and 3, the first meter-in solenoid proportional valve 7 is de-energized and the first meter-in spool 5 is placed in the first neutral position. With the first meter-in spool 5 in the first neutral position, the first pump port P1 and the first supply port S1 are closed.
In addition, the second meter-in electromagnetic proportional valve 8 is de-energized to place the second meter-in spool 6 in the second neutral position. With the second meter-in spool 6 in the second neutral position, the second pump port P2 and the second supply port S2 are closed.

In addition, the first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17 are de-energized, and the meter-out spool 15 is placed in the center position (i.e., the neutral position). With the meter-out spool 15 in the center position, the first tank port T1, the second tank port T2, the first drain port D1, and the second drain port D2 are closed.
When the first pump 110A and the second pump 110B are driven by a prime mover (not shown), a predetermined flow rate of hydraulic oil is discharged from the discharge port of each of the pumps 110A and 110B. For example, the discharged hydraulic oil may be returned to the tank 120 via a return circuit (not shown).
In this state, the boom 104 (see FIG. 1) is held stationary.

Next, an example of raising the boom 104 using the independent metering valve 2 will be described with reference to Figs.
2 and 4, the first meter-in spool 5 is moved in the direction of arrow A1 to be disposed at the first supply position. In this case, by switching the first meter-in solenoid proportional valve 7 to an energized state, the first meter-in spool 5 is moved in a direction that narrows the intermediate portion 13 to be disposed at the first supply position. By disposing the first meter-in spool 5 at the first supply position, the first pump port P1 and the first supply port S1 are communicated with each other through the first meter-in flow path 11.

Also, the second meter-in spool 6 is moved in the direction of arrow A2 to be disposed at the second supply position. In this case, by switching the second meter-in electromagnetic proportional valve 8 to an energized state, the second meter-in spool 6 is moved in a direction narrowing the intermediate portion 13 to be disposed at the second supply position. By disposing the second meter-in spool 6 at the second supply position, the second pump port P2 and the second supply port S2 are communicated with each other through the second meter-in flow path 12.
As a result, the first pump port P1 and the second pump port P2 communicate with the bridge flow channel 30 via the first supply port S1 and the second supply port S2, etc., respectively.

Furthermore, the meter-out spool 15 is moved in the direction of arrow A3 to be disposed in the first discharge position. In this case, the first meter-out solenoid proportional valve 16 is switched to a de-energized state and the second meter-out solenoid proportional valve 17 is switched to an energized state, so that the meter-out spool 15 is moved in the direction of the first meter-out solenoid proportional valve 16 to be disposed in the first discharge position.
By disposing the meter-out spool 15 in the first discharge position, the first discharge port D1 and the first tank port T1 communicate with each other through the first notched flow passage 21. As a result, the rod port Rp communicates with the second tank port T1 via the first notched flow passage 21, the second discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, and the like.

Furthermore, by disposing the meter-out spool 15 in the first discharge position, the bridge flow passage 30 and the second discharge port D2 are communicated with each other through the second notched flow passage 22. Specifically, the bridge flow passage 30 is communicated with the head port Hp via the second notched flow passage 22, the second discharge port D2, the second head flow passage 34, the first head flow passage 33, the head side flow passage 134, etc. In other words, the second notched flow passage 22 is communicated with the bridge flow passage 30, and is communicated with the head port Hp via the second discharge port D2, etc.
Furthermore, by disposing the meter-out spool 15 in the first discharge position, the second tank port T2 is blocked by the land 15b of the meter-out spool 15, etc.

In this state, hydraulic oil discharged from the discharge port of the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V1 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. Hydraulic oil discharged from the discharge port of the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V2 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42.

As a result, the hydraulic oil discharged from the first pump 110A and the hydraulic oil discharged from the second pump 110B join at the bridge flow passage 30. The hydraulic oil that joins at the bridge flow passage 30 is guided to the second head flow passage 34 as indicated by arrow V3 via the second notched flow passage 22 and the second discharge port D2. The hydraulic oil guided to the second head flow passage 34 flows into the cylinder head side of the cylinder 114 as indicated by arrow V3 via the first head flow passage 33, the head side flow passage 134, and the head port Hp.

On the other hand, the hydraulic oil on the rod end side of the cylinder 114 is guided to the second rod flow path 32 as indicated by arrow V4 via the rod port Rp, the rod side flow path 133, and the first rod flow path 31. The hydraulic oil guided to the second rod flow path 32 is discharged (returned) to the tank 120 as indicated by arrow V4 via the first discharge port D1, the first notched flow path 21, the first tank port T1, and the first discharge flow path 135. That is, in the first embodiment, when the boom 104 is raised, the hydraulic oil from the first discharge port D1 is returned to the tank 120.
As a result, the piston rod 115 of the hydraulic cylinder 113 is pushed out as indicated by an arrow E1 so as to protrude from the cylinder 114, and the boom 104 (see FIG. 1) is raised.

In this way, the independent metering valve 2 has two independent meter-in spools, a first meter-in spool 5 and a second meter-in spool 6. The first meter-in spool 5 has a first meter-in flow path 11 that leads to the first pump 110A. The second meter-in spool 6 has a second meter-in flow path 12 that leads to the second pump 110B. The first meter-in flow path 11 and the second meter-in flow path 12 are connected to a bridge flow path 30. The bridge flow path 30 is a flow path that supplies hydraulic oil discharged from at least one of the first pump 110A and the second pump 110B to the cylinder head side or the rod end side of the cylinder 114.

Therefore, the first meter-in spool 5 and the second meter-in spool 6 can be individually controlled to guide hydraulic oil discharged from, for example, one first pump 110A to the bridge flow passage 30. Also, each meter-in spool 5, 6 can be individually controlled to guide hydraulic oil discharged from, for example, one second pump 110B to the bridge flow passage 30. Also, each meter-in spool 5, 6 can be individually controlled to guide hydraulic oil discharged from, for example, two pumps, the first pump 110A and the second pump 110B, to the bridge flow passage 30.

Here, the first pump 110A and the second pump 110B have, for example, the same pump capacity, and the discharge amount per rotation can be adjusted in the range of 0 to 100%. Therefore, the independent metering valve 2 makes it possible to adjust the discharge amount to twice the discharge amount of each of the first pump 110A and the second pump 110B. In other words, it is possible to arbitrarily (freely) change the ratio of hydraulic oil supplied from the first pump 110A and the second pump 110B to the rod end side of the cylinder 114 within a range twice the discharge amount of each pump 110A, 110B. This allows the flow rate of hydraulic oil flowing into the rod end side of the cylinder 114 to be highly efficiently adjusted when the boom 104 is raised.

Next, an example of lowering the boom 104 using the independent metering valve 2 will be described with reference to Figs.
2 and 5, the first meter-in spool 5 and the second meter-in spool 6 are held in the first supply position and the second supply position, respectively, in the same manner as when the boom 104 is raised. In this state, the meter-out spool 15 is moved in the direction of arrow A4 to be disposed in the second discharge position. In this case, the second meter-out solenoid proportional valve 17 is switched to a de-energized state and the first meter-out solenoid proportional valve 16 is switched to an energized state, whereby the meter-out spool 15 is moved toward the second meter-out solenoid proportional valve 17 to be disposed in the second discharge position.

By placing the meter-out spool 15 in the second discharge position, the second discharge port D2 and the second tank port T2 are connected by the second notched flow path 22. As a result, the second tank port T2 is connected to the head port Hp via the second notched flow path 22, the second discharge port D2, the second head flow path 34, the first head flow path 33, the head side flow path 134, etc.

Moreover, by disposing the meter-out spool 15 at the second discharge position, the bridge flow passage 30 and the first discharge port D1 communicate with each other through the first notched flow passage 21. Specifically, the rod port Rp communicates with the bridge flow passage 30 via the first notched flow passage 21, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, and the like. In other words, the first notched flow passage 21 communicates with the bridge flow passage 30 and communicates with the rod port Rp via the first discharge port D1, and the like.
Furthermore, by disposing the meter-out spool 15 in the second discharge position, the first tank port T1 is blocked by the land 15b of the meter-out spool 15, etc.

In this state, similar to when the boom 104 is raised, the hydraulic oil discharged from the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V1 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. The hydraulic oil discharged from the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V2 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42.

As a result, the hydraulic oil discharged from the first pump 110A and the hydraulic oil discharged from the second pump 110B join in the bridge flow passage 30. The hydraulic oil that joins in the bridge flow passage 30 is guided to the second rod flow passage 32 as indicated by arrow V5 via the first notched flow passage 21 and the first discharge port D1. The hydraulic oil guided to the second rod flow passage 32 flows into the rod end side of the cylinder 114 as indicated by arrow V5 via the first rod flow passage 31, the rod side flow passage 133, and the rod port Rp.

On the other hand, the hydraulic oil on the cylinder head side of the cylinder 114 is guided as indicated by arrow V6 to the second head flow path 34 via the head port Hp, the head-side flow path 134, and the first head flow path 33. The hydraulic oil guided to the second head flow path 34 is discharged (returned) to the tank 120 as indicated by arrow V6 via the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136. That is, in the first embodiment, when the boom 104 (see FIG. 1 ) is lowered, the hydraulic oil from the second discharge port D2 is returned to the tank 120.
As a result, the piston rod 115 of the hydraulic cylinder 113 is retracted as indicated by an arrow E2 so as to be pushed into the cylinder 114, and the boom 104 (see FIG. 1) is lowered.

Here, the independent metering valve 2 can individually control the first meter-in spool 5 and the second meter-in spool 6, in the same way as in the case of raising the boom 104. By individually controlling the meter-in spools 5, 6, for example, it is possible to guide the hydraulic oil discharged from at least one of the first pump 110A and the second pump 110B to the bridge flow path 30.
This makes it possible to adjust the discharge rate to twice the discharge rate of each of the first pump 110A and the second pump 110B. In other words, it becomes possible to arbitrarily (freely) change the ratio of hydraulic oil supplied from the first pump 110A and the second pump 110B to the cylinder head side of the cylinder 114 within a range twice the discharge rate of each of the pumps 110A and 110B. This makes it possible to highly efficiently adjust the flow rate of hydraulic oil flowing into the cylinder head side of the cylinder 114 when lowering the boom 104.

In this way, the drive control method for the hydraulic actuator 111 includes a flow rate adjustment process for adjusting the combined flow rate of the hydraulic oil discharged from the two pumps 110A, 110B by controlling the drive of the two meter-in spools 5, 6, and a fluid supply process for supplying the hydraulic oil whose combined flow rate has been adjusted by the flow rate adjustment process to the hydraulic actuator 111 to drive the hydraulic actuator 111. Since the following embodiments also include similar processes, the terms flow rate adjustment process and fluid supply process will be omitted in the following embodiments.

As described above, the independent metering valve 2 of the hydraulic system 109 according to the first embodiment includes two independent meter-in spools, the first meter-in spool 5 and the second meter-in spool 6. The first meter-in spool 5 has a first meter-in passage 11 that communicates with the first pump 110A. The second meter-in spool 6 has a second meter-in passage 12 that communicates with the second pump 110B. The first meter-in passage 11 and the second meter-in passage 12 communicate with the bridge passage 30. The bridge passage 30 is a passage that supplies hydraulic oil discharged from at least one of the first pump 110A and the second pump 110B to the rod end side or the cylinder head side of the cylinder 114.

Therefore, according to the drive control method of the independent metering valve 2, the hydraulic system 109, and the hydraulic actuator 111, it is possible to adjust the discharge rate to twice the discharge rate of each of the first pump 110A and the second pump 110B. In other words, it is possible to arbitrarily (freely) change the ratio of hydraulic oil supplied from the first pump 110A and the second pump 110B to the rod end side of the cylinder 114 within a range twice the discharge rate of each pump 110A, 110B. This allows for high-performance adjustment of the flow rate of hydraulic oil flowing into the rod end side or cylinder head side of the cylinder 114 when raising or lowering the boom 104.

The first meter-in spool 5 and the second meter-in spool 6 are housed together in a single hole of the first spool hole 10. This allows the number of first spool holes 10 to be reduced, simplifying the configuration of the hydraulic system 109 and the independent metering valve 2.

Furthermore, the first spool hole 10 has an intermediate portion 13 in the center in the axial direction. That is, the intermediate portion 13 is formed between the first meter-in spool 5 and the second meter-in spool 6, which face each other. The intermediate portion 13 is connected to the tank 120 via the third discharge flow path 137. Therefore, hydraulic oil can be moved between the intermediate portion 13 and the tank 120 in response to the change in volume of the intermediate portion 13 caused by the movement of the first meter-in spool 5 and the second meter-in spool 6.

Specifically, when the first meter-in spool 5 and the second meter-in spool 6 move so that the volume of the intermediate section 13 becomes smaller, the hydraulic oil in the intermediate section 13 can be discharged into the tank 120. As a result, it is possible to prevent the pressure of the hydraulic oil in the intermediate section 13 from increasing, making it difficult for the meter-in spools 5 and 6 to move. This allows the first meter-in spool 5 and the second meter-in spool 6 to move smoothly inside the first spool hole 10.

In addition, by positioning the meter-out spool 15 in the first discharge position (the position shown in Figure 4), the second notched flow passage 22 can be connected to the bridge flow passage 30, and the head port Hp can be connected to the second discharge port D2, etc.
Furthermore, by positioning the meter-out spool 15 in the second discharge position (the position shown in FIG. 5 ), the first notched flow passage 21 can be connected to the bridge flow passage 30 and can also be connected to the rod port Rp via the first discharge port D1, etc.

The bridge flow passage 30 is connected to the first meter-in flow passage 11 of the first meter-in spool 5 and the second meter-in flow passage 12 of the second meter-in spool 6. Therefore, the meter-out spool 15 can be shared by both the first meter-in spool 5 and the second meter-in spool 6. This allows the number of meter-out spools 15 to be reduced to one, simplifying the configuration of the hydraulic system 109 and the independent metering valve 2.

The first meter-in spool 5, the second meter-in spool 6, and the meter-out spool 15 are all mounted together in one valve body 3. This allows the number of valve bodies 3 to be reduced, and the hydraulic system 109 and the independent metering valve 2 to be simplified and configured compactly.

The independent metering valve, hydraulic system, and hydraulic actuator drive control method of the second to fourth embodiments will be described below with reference to Figures 6 to 16. Note that in the second to fourth embodiments, the same reference numerals are used for configurations that are the same as or similar to those in the first embodiment, and detailed descriptions will be omitted.

[Second embodiment]
<Independent metering valve>
6 is an explanatory diagram showing an example of a hydraulic system (an example of a fluid system in the claims) 150 when the boom 104 is held stationary by an independent metering valve (an example of a control valve in the claims) 151 of the second embodiment. Fig. 6 corresponds to an explanatory diagram for holding the piston rod 115 of the hydraulic cylinder 113 stationary.
6, the independent metering valve 151 of the second embodiment includes a first meter-in spool 153 and a second meter-in spool 154. Other configurations of the independent metering valve 151 of the second embodiment are similar to those of the independent metering valve 2 of the first embodiment described above.

The first meter-in spool 153 has a first shortcut recess 153a (an example of a recess in the claims), and other configurations are similar to those of the first meter-in spool 5 of the first embodiment. The first shortcut recess 153a is formed, for example, by a step recessed all around with respect to the first land 153b. Note that the first shortcut recess 153a may be formed, for example, by a step and a notch.
The first shortcut recess 153a is formed on one side of one end of the bridge passage 30. The first shortcut recess 153a is entirely disposed between the first rod passage 31 and the second rod passage 32 when the first meter-in spool 153 is disposed in the first neutral position (the position shown in FIG. 6 ).

7 is an explanatory diagram showing an example of an operation when the boom 104 (see FIG. 1) is raised by the hydraulic system 150 of the second embodiment. FIG. 7 corresponds to an explanatory diagram of the action of pushing out the piston rod 115 of the hydraulic cylinder 113.
8 is an explanatory diagram showing an example of an operation when lowering the boom 104 (see FIG. 1) in the hydraulic system 150 of the second embodiment. FIG. 8 corresponds to an explanatory diagram of the action of retracting the piston rod 115 of the hydraulic cylinder 113.

As shown in Figures 7 and 8, when the first meter-in spool 153 is placed in the first supply position (the position shown in Figures 7 and 8), a portion of the first shortcut recess 153a is placed (interposed) between the first rod flow path 31 and the second rod flow path 32. Therefore, the first shortcut recess 153a ensures a large cross-sectional area of the flow path interposed between the first rod flow path 31 and the second rod flow path 32.

Moreover, when the meter-out spool 15 is disposed at the second discharge position (the position shown in FIG. 8 ), the first shortcut recess 153a communicates with the bridge passage 30 via the second rod passage 32, the first discharge port D1, and the first notched passage 21. Furthermore, when the meter-out spool 15 is disposed at the second discharge position, the first shortcut recess 153a communicates with the rod port Rp via the first rod passage 31 and the rod-side passage 133.
That is, the first shortcut recess 153a communicates the bridge passage 30 with the rod port Rp (specifically, the rod end side of the cylinder 114) when the meter-out spool 15 is positioned in the second discharge position.

On the other hand, when the meter-out spool 15 is disposed at the first discharge position (the position shown in FIG. 7 ), the first shortcut recess 153a communicates with the tank 120 via the second rod flow path 32, the first discharge port D1, the first notched flow path 21, the first tank port T1, and the first discharge flow path 135. Furthermore, when the meter-out spool 15 is disposed at the first discharge position, the first shortcut recess 153a communicates with the rod port Rp via the first rod flow path 31 and the rod-side flow path 133.
That is, the first shortcut recess 153a communicates the rod port Rp (specifically, the rod end side of the cylinder 114) with the tank 120 when the meter-out spool 15 is positioned in the first discharge position.

6, the second meter-in spool 154 has a second shortcut recess 154a (an example of another recess in the claims), and other configurations are similar to those of the second meter-in spool 6 of the first embodiment. The second shortcut recess 154a is formed, for example, by a step recessed over the entire circumference relative to the second land 154b. The second shortcut recess 154a may be formed by a step and a notch.
The second shortcut recess 154a is formed on the other side of the other end of the bridge passage 30. The second shortcut recess 154a is entirely disposed between the first head passage 33 and the second head passage 34 when the second meter-in spool 154 is disposed in the second neutral position (the position shown in FIG. 6 ).

As shown in Figures 7 and 8, when the second meter-in spool 154 is placed in the second supply position (the position shown in Figures 7 and 8), a portion of the second shortcut recess 154a is disposed (interposed) between the first head flow path 33 and the second head flow path 34. Therefore, the second shortcut recess 154a ensures a large cross-sectional area of the flow path interposed between the first head flow path 33 and the second head flow path 34.

Furthermore, when the meter-out spool 15 is disposed at the second discharge position (the position shown in FIG. 8 ), the second shortcut recess 154a communicates with the tank 120 via the second head flow path 34, the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136. Furthermore, when the meter-out spool 15 is disposed at the second discharge position, the second shortcut recess 154a communicates with the head port Hp via the first head flow path 33 and the head-side flow path 134.
That is, the second shortcut recess 154a communicates the head port Hp (specifically, the cylinder head side of the cylinder 114) with the tank 120 when the meter-out spool 15 is positioned in the second discharge position.

Furthermore, when the meter-out spool 15 is disposed in the first discharge position (the position shown in FIG. 7 ), the second shortcut recess 154a communicates with the bridge passage 30 via the second head passage 34, the second discharge port D2, and the second notched passage 22. Furthermore, when the meter-out spool 15 is disposed in the first discharge position, the second shortcut recess 154a communicates with the head port Hp via the first head passage 33 and the head-side passage 134.
That is, the second shortcut recess 154a communicates the bridge passage 30 with the head port Hp (specifically, the cylinder head side of the cylinder 114) when the meter-out spool 15 is positioned in the first discharge position.

<Method of controlling hydraulic actuator drive using independent metering valve and hydraulic system>
Next, a method of controlling the drive of the hydraulic actuator 111 (hydraulic cylinder 113) by the independent metering valve 151 and the hydraulic system 150 will be described with reference to FIGS.
First, an example in which the boom 104 (see FIG. 1) of the construction machine 100 is held stationary by the independent metering valve 151 will be described with reference to FIG.
6, the first meter-in spool 153 is placed in a first neutral position, and the first pump port P1 and the first supply port S1 are blocked by the first meter-in spool 153. The second meter-in spool 154 is placed in a second neutral position, and the second pump port P2 and the second supply port S2 are blocked by the second meter-in spool 154.

Furthermore, the meter-out spool 15 is disposed in a central position, and the first tank port T1, the second tank port T2, the first discharge port D1, and the second discharge port D2 are blocked by the meter-out spool 15.
In this state, the hydraulic oil discharged from each discharge port of the first pump 110A and the second pump 110B is returned to the tank 120, for example, via a return circuit not shown, and the boom 104 (see Figure 1) is maintained in a stationary state.

Next, an example of raising the boom 104 using the independent metering valve 151 will be described with reference to FIG.
7, by moving the first meter-in spool 153 in the direction of arrow A5 and placing it in the first supply position, the first pump port P1 and the first supply port S1 are communicated through the first meter-in flow path 11. Also, by moving the second meter-in spool 6 in the direction of arrow A6 and placing it in the second supply position, the second pump port P2 and the second supply port S2 are communicated through the second meter-in flow path 12.
As a result, the first pump port P1 and the second pump port P2 communicate with the bridge flow passage 30 via the first supply port S1 and the second supply port S2, etc., respectively.

Furthermore, the meter-out spool 15 is moved in the direction of arrow A7 to be placed in the first discharge position. By placing the meter-out spool 15 in the first discharge position, the first discharge port D1 and the first tank port T1 are connected by the first notched flow path 21. As a result, the rod port Rp is connected to the first tank port T1 via the first notched flow path 21, the first discharge port D1, the second rod flow path 32, the first rod flow path 31, the rod side flow path 133, etc.

Furthermore, by disposing the meter-out spool 15 at the first discharge position, the second notched flow passage 22 is communicated with the bridge flow passage 30 and also communicated with the head port Hp via the second discharge port D2, etc. Specifically, the head port Hp is communicated with the bridge flow passage 30 via the second notched flow passage 22, the second discharge port D2, the second head flow passage 34, the first head flow passage 33, the head side flow passage 134, etc.
Furthermore, the second tank port T2 is blocked by the meter-out spool 15 disposed in the second discharge position.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V7 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. The hydraulic oil discharged from the discharge port of the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V8 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join in the bridge flow passage 30.

The joined hydraulic oil passes through the second notched flow passage 22 and the second discharge port D2, and is guided as indicated by the arrow V9 to the second head flow passage 34. The hydraulic oil guided to the second head flow passage 34 passes through the first head flow passage 33, the head-side flow passage 134, and the head port Hp, and flows into the cylinder head side of the cylinder 114, as indicated by the arrow V9.
Here, the second shortcut recess 154a is interposed between the first head flow passage 33 and the second head flow passage 34. Therefore, a large cross-sectional area of the flow passage interposed between the first head flow passage 33 and the second head flow passage 34 can be ensured. This makes it possible to reduce the pressure loss of the hydraulic oil supplied from the bridge flow passage 30 to the cylinder head side of the cylinder 114. That is, the hydraulic oil can be efficiently supplied to the cylinder head side of the cylinder 114.

On the other hand, the hydraulic oil on the rod end side of the cylinder 114 is guided as indicated by an arrow V10 to the second rod flow path 32 via the rod port Rp, the rod side flow path 133, and the first rod flow path 31. The hydraulic oil guided to the second rod flow path 32 is discharged (returned) to the tank 120 as indicated by an arrow V10 via the first discharge port D1, the first notched flow path 21, the first tank port T1, and the first discharge flow path 135.
Here, the first shortcut recess 153a is interposed between the first rod flow path 31 and the second rod flow path 32. Therefore, a large cross-sectional area of the flow path interposed between the first rod flow path 31 and the second rod flow path 32 can be secured. This makes it possible to increase the flow rate of the hydraulic oil returning from the rod end side of the cylinder 114 to the tank 120, and the hydraulic oil can be efficiently returned from the rod end side to the tank 120.

By supplying hydraulic oil to the cylinder head side of the cylinder 114 and returning the hydraulic oil to the tank 120 from the rod end side, the piston rod 115 is pushed out of the cylinder 114 as shown by arrow E3, and the boom 104 (see Figure 1) is raised.

Next, an example of lowering the boom 104 using the independent metering valve 151 will be described with reference to FIG.
8, the first meter-in spool 153 and the second meter-in spool 154 are held in the first supply position and the second supply position, respectively, in the same manner as when the boom 104 is raised. In this state, by moving the meter-out spool 15 in the direction of arrow A8 and placing it in the second discharge position, the second discharge port D2 and the second tank port T2 are communicated with each other through the second notched flow path 22. As a result, the second tank port T2 is communicated with the head port Hp via the second notched flow path 22, the second discharge port D2, the second head flow path 34, the first head flow path 33, the head side flow path 134, etc.

Moreover, by disposing the meter-out spool 15 at the second discharge position, the first notched flow passage 21 communicates with the bridge flow passage 30 and communicates with the rod port Rp via the first discharge port D1, etc. Specifically, the rod port Rp communicates with the bridge flow passage 30 via the first notched flow passage 21, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, etc.
Furthermore, the first tank port T1 is blocked by the meter-out spool 15 disposed in the second discharge position.

In this state, similar to when the boom 104 is raised, the hydraulic oil discharged from the first pump 110A and the second pump 110B join in the bridge flow passage 30. The joined hydraulic oil passes through the first notched flow passage 21 and the first discharge port D1 and is guided to the second rod flow passage 32 as indicated by arrow V11. The hydraulic oil guided to the second rod flow passage 32 passes through the first rod flow passage 31, the rod side flow passage 133, and the rod port Rp and flows into the rod end side of the cylinder 114 as indicated by arrow V11.

Here, the first shortcut recess 153a is interposed between the first rod flow path 31 and the second rod flow path 32. Therefore, a large cross-sectional area of the flow path interposed between the first rod flow path 31 and the second rod flow path 32 can be ensured. This reduces the pressure loss of the hydraulic oil supplied from the bridge flow path 30 to the rod end side of the cylinder 114. In other words, the hydraulic oil can be efficiently supplied to the rod end side of the cylinder 114.

On the other hand, the hydraulic oil on the cylinder head side of the cylinder 114 is guided as indicated by the arrow V12 to the second head flow path 34 via the head port Hp, the head side flow path 134, and the first head flow path 33. The hydraulic oil guided to the second head flow path 34 is discharged (returned) to the tank 120 as indicated by the arrow V12 via the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136.
Here, the second shortcut recess 154a is interposed between the first head flow path 33 and the second head flow path 34. This makes it possible to ensure a large cross-sectional area of the flow path interposed between the first head flow path 33 and the second head flow path 34. This makes it possible to increase the flow rate of the hydraulic oil returning from the cylinder head side of the cylinder 114 to the tank 120, and allows the hydraulic oil to be efficiently returned from the cylinder head side to the tank 120.

In this way, by supplying hydraulic oil to the rod end side of the cylinder 114 and returning the hydraulic oil from the cylinder head side to the tank 120, the piston rod 115 is pulled into the cylinder 114 as shown by arrow E4, and the boom 104 (see Figure 1) is lowered.

As described above, similar to the first embodiment, the independent metering valve 151 of the hydraulic system 150 according to the second embodiment includes two independent meter-in spools, the first meter-in spool 153 and the second meter-in spool 154. As a result, according to the drive control method of the independent metering valve 151, the hydraulic system 150, and the hydraulic actuator 111 (hydraulic cylinder 113), when the boom 104 is raised or lowered, similar to the first embodiment, the flow rate of the hydraulic oil flowing into the rod end side or the cylinder head side of the cylinder 114 can be highly efficiently adjusted.
Furthermore, the method of controlling the drive of the independent metering valve 151, the hydraulic system 150, and the hydraulic actuator 111 (hydraulic cylinder 113) according to the second embodiment provides the same effects as those of the first embodiment.

Furthermore, the independent metering valve 151 of the hydraulic system 150 according to the second embodiment has a first shortcut recess 153a in the first meter-in spool 153 and a second shortcut recess 154a in the second meter-in spool 154. As a result, according to the drive control method for the independent metering valve 151, the hydraulic system 150, and the hydraulic actuator 111 (hydraulic cylinder 113), as described above, the pressure loss of the hydraulic oil flowing into the hydraulic cylinder 113 can be reduced, and the flow rate of the hydraulic oil discharged from the hydraulic cylinder 113 can be increased.

[Third embodiment]
<Independent metering valve>
9 is an explanatory diagram showing an example of a hydraulic system (an example of a fluid system in the claims) 170 when the boom 104 is held stationary by an independent metering valve (an example of a control valve in the claims) 171 of the third embodiment. Fig. 9 corresponds to an explanatory diagram for holding the piston rod 115 of the hydraulic cylinder 113 stationary.
9, the independent metering valve 171 of the third embodiment includes a valve body (an example of a block body in the claims) 173, a first meter-in spool 174, and a second meter-in spool 175. Other configurations of the independent metering valve 171 of the third embodiment are similar to those of the independent metering valve 2 of the first embodiment.

The valve body 173 has a third tank port T3 and a fourth tank port T4, and the other configurations are the same as those of the valve body 3 of the first embodiment. The third tank port T3 is located on one side of the second rod flow path 32 and opens into the first spool hole 10 (see FIG. 2). The third tank port T3 communicates with the tank 120 via a fourth discharge flow path 177. The fourth tank port T4 is located on the other side of the second head flow path 34 and opens into the first spool hole 10. The fourth tank port T4 communicates with the tank 120 via a fifth discharge flow path 178.

The first meter-in spool 174 has a first shortcut recess 174a (an example of a recess in the claims), and other configurations are similar to those of the first meter-in spool 5 of the first embodiment. The first shortcut recess 174a is formed, for example, by a step recessed over the entire circumference relative to the first land 174b. Note that the first shortcut recess 174a may be formed, for example, by a step and a notch.
The first shortcut recess 174a is formed on one side of one end of the bridge flow passage 30. The first shortcut recess 174a communicates with the third tank port T3 when the first meter-in spool 174 is disposed in the first neutral position (the position shown in FIG. 9 ).

10 is an explanatory diagram showing an example of an operation when the boom 104 (see FIG. 1) is raised by the hydraulic system 170 of the third embodiment. FIG. 10 corresponds to an explanatory diagram of the action of pushing out the piston rod 115 of the hydraulic cylinder 113.
10, when the first meter-in spool 174 is located at the first supply position (the position shown in FIG. 10), a portion of the other side of the first shortcut recess 174a is located (interposed) between the first rod flow path 31 and the second rod flow path 32. At this time, a portion of one side of the first shortcut recess 174a communicates with the third tank port T3.
Therefore, the first shortcut recess 174a communicates the first rod flow passage 31 with the third tank port T3. As a result, the rod port Rp (specifically, the rod end side of the cylinder 114) communicates with the tank 120 via the rod-side flow passage 133, the first rod flow passage 31, the first shortcut recess 174a, the third tank port T3, and the fourth discharge flow passage 177.

When the meter-out spool 15 is placed in the first discharge position (the position shown in FIG. 10), the rod port Rp communicates with the second rod flow path 32 via the rod side flow path 133 and the first rod flow path 31. Furthermore, the second rod flow path 32 communicates with the tank 120 via the first discharge port D1, the first notched flow path 21, the first tank port T1, and the first discharge flow path 135. That is, the rod port Rp (specifically, the rod end side of the cylinder 114) communicates with the tank 120 via the first notched flow path 21 of the meter-out spool 15 when the meter-out spool 15 is placed in the first discharge position.

The second meter-in spool 175 has a second shortcut recess 175a (an example of another recess in the claims). Other configurations of the second meter-in spool 175 are similar to those of the second meter-in spool 6 in the first embodiment. The second shortcut recess 175a is formed, for example, by a step recessed over the entire circumference relative to the second land 175b. Note that the second shortcut recess 175a may be formed, for example, by a step and a notch.
The second shortcut recess 175a is formed on the other side of the other end of the bridge flow passage 30. The second shortcut recess 175a is disposed (interposed) between the first head flow passage 33 and the second head flow passage 34 when the second meter-in spool 175 is disposed in the second neutral position (the position shown in FIG. 9 ).

As shown in FIG. 10, when the second meter-in spool 175 is disposed in the second supply position (the position shown in FIG. 10), the second shortcut recess 175a has a portion on one side that is connected to the bridge passage 30. At this time, the first shortcut recess 174a has a portion on the other side that is connected to the first head passage 33. Therefore, the second shortcut recess 175a connects the bridge passage 30 to the first head passage 33. As a result, the bridge passage 30 connects to the head port Hp (specifically, the cylinder head side of the cylinder 114) via the second shortcut recess 175a, the first head passage 33, and the head side passage 134.

When the meter-out spool 15 is positioned at the first discharge position (the position shown in FIG. 10), the bridge flow passage 30 communicates with the second head flow passage 34 via the second notched flow passage 22 and the second discharge port D2. The second head flow passage 34 communicates with the head port Hp via the first head flow passage 33 and the head side flow passage 134. That is, when the meter-out spool 15 is positioned at the first discharge position, the bridge flow passage 30 communicates with the head port Hp (specifically, the cylinder head side of the cylinder 114) via the second notched flow passage 22.

<Method of controlling hydraulic actuator drive using independent metering valve and hydraulic system>
Next, a method of controlling the drive of the hydraulic actuator 111 (hydraulic cylinder 113) by the independent metering valve 171 and the hydraulic system 170 will be described with reference to FIGS.
First, an example in which the boom 104 (see FIG. 1) of the construction machine 100 is held stationary by an independent metering valve 171 will be described with reference to FIG.
9, the first meter-in spool 174 is placed in a first neutral position, and the first pump port P1 and the first supply port S1 are blocked by the first meter-in spool 174. The second meter-in spool 175 is placed in a second neutral position, and the second pump port P2 and the second supply port S2 are blocked by the second meter-in spool 175.

Furthermore, the meter-out spool 15 is placed in the central position (the position shown in FIG. 9 ) and the first tank port T1, the second tank port T2, the first drain port D1, and the second drain port D2 are blocked by the meter-out spool 15.
In this state, the hydraulic oil discharged from each discharge port of the first pump 110A and the second pump 110B is returned to the tank 120, for example, via a return circuit not shown, and the boom 104 (see Figure 1) is maintained in a stationary state.

Next, an example of raising the boom 104 using the independent metering valve 171 will be described with reference to FIG.
As shown in FIG. 10, the first meter-in spool 174 is moved in the direction of arrow A9 to the first supply position, thereby establishing communication between the first pump port P1 and the first supply port S1 through the first meter-in passage 11.
Furthermore, by disposing the first meter-in spool 174 at the first supply position, the first rod flow path 31 and the third tank port T3 communicate with each other through the first shortcut recess 174a. As a result, the rod port Rp communicates with the third tank port T3 via the first shortcut recess 174a, the first rod flow path 31, the rod side flow path 133, etc.

Furthermore, by moving the second meter-in spool 175 in the direction of arrow A10 and placing it in the second supply position, the second pump port P2 and the second supply port S2 are communicated with each other through the second meter-in flow path 12. As a result, the first pump port P1 and the second pump port P2 are communicated with the bridge flow path 30 via the first supply port S1 and the second supply port S2, etc., respectively.
Furthermore, by disposing the second meter-in spool 6 at the second supply position, the bridge flow passage 30 and the first head flow passage 33 are communicated with each other at the second shortcut recess 175a. As a result, the bridge flow passage 30 is communicated with the head port Hp via the second shortcut recess 175a, the first head flow passage 33, the head side flow passage 134, etc.

The meter-out spool 15 is also moved in the direction of arrow A11 to be placed in the first discharge position. By placing the meter-out spool 15 in the first discharge position, the first discharge port D1 and the first tank port T1 are connected by the first notched flow path 21. As a result, the rod port Rp is connected to the first tank port T1 via the first notched flow path 21, the first discharge port D1, the second rod flow path 32, the first rod flow path 31, the rod side flow path 133, etc.

Furthermore, by disposing the meter-out spool 15 at the first discharge position, the second notched flow passage 22 is communicated with the bridge flow passage 30 and also communicated with the head port Hp via the second discharge port D2, etc. Specifically, the head port Hp is communicated with the bridge flow passage 30 via the second notched flow passage 22, the second discharge port D2, the second head flow passage 34, the first head flow passage 33, the head side flow passage 134, etc.
In addition, the second tank port T2 is blocked by the meter-out spool 15 disposed in the first discharge position.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V13 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. The hydraulic oil discharged from the discharge port of the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V14 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join in the bridge flow passage 30.

A portion of the joined hydraulic oil is guided to the first head flow passage 33 as indicated by arrow V15 through the second shortcut recess 175a. The remainder of the joined hydraulic oil is guided to the first head flow passage 33 as indicated by arrow V16 through the second notched flow passage 22, the second discharge port D2, and the second head flow passage 34. Hereinafter, the portion of the joined hydraulic oil is referred to as the "first hydraulic oil" and the remainder of the joined hydraulic oil is referred to as the "second hydraulic oil."
The first and second hydraulic oils guided to the first head flow passage 33 flow through the head side flow passage 134 and the head port Hp into the cylinder head side of the cylinder 114 as indicated by an arrow V17.

In this way, the first hydraulic oil among the hydraulic oils merged in the bridge flow passage 30 can be guided to the first head flow passage 33 via the second shortcut recess 175a without passing through the second notched flow passage 22 of the meter-out spool 15. This reduces the pressure loss of the hydraulic oil supplied from the bridge flow passage 30 to the cylinder head side of the cylinder 114. In other words, the hydraulic oil can be efficiently supplied to the cylinder head side of the cylinder 114.

On the other hand, the hydraulic oil on the rod end side of the cylinder 114 is guided to the first rod flow path 31 as indicated by an arrow V18 via the rod port Rp and the rod side flow path 133. A part of the hydraulic oil guided to the first rod flow path 31 is discharged (returned) to the tank 120 as indicated by an arrow V19 via the first shortcut recess 174a and the fourth discharge flow path 177.
The remainder of the hydraulic oil guided to the first rod flow path 31 is discharged (returned) to the tank 120 as indicated by arrow V20 via the second rod flow path 32, the first discharge port D1, the first notched flow path 21, the first tank port T1, and the first discharge flow path 135. Hereinafter, the part of the hydraulic oil guided to the first rod flow path 31 will be referred to as the "third hydraulic oil" and the remainder of the guided hydraulic oil will be referred to as the "fourth hydraulic oil."

In this way, the third hydraulic oil of the hydraulic oil guided to the first rod flow path 31 can be guided to the tank 120 via the first shortcut recess 174a without passing through the first notched flow path 21 of the meter-out spool 15. This increases the flow rate of hydraulic oil returning to the tank 120 from the rod end side of the cylinder 114, allowing the hydraulic oil to be efficiently returned from the rod end side to the tank 120.

By supplying hydraulic oil to the cylinder head side of the cylinder 114 and returning the hydraulic oil to the tank 120 from the rod end side, the piston rod 115 is pushed out of the cylinder 114 as shown by arrow E5, and the boom 104 (see Figure 1) is raised.

As described above, similar to the first embodiment, the independent metering valve 171 of the hydraulic system 170 according to the third embodiment includes two independent meter-in spools, the first meter-in spool 174 and the second meter-in spool 175. As a result, according to the drive control method of the independent metering valve 171, the hydraulic system 170, and the hydraulic actuator 111 (hydraulic cylinder 113), when raising or lowering the boom 104, similar to the first embodiment, it is possible to highly efficiently adjust the flow rate of hydraulic oil flowing into the rod end side or the cylinder head side of the cylinder 114.
Furthermore, the method of controlling the drive of the independent metering valve 171, the hydraulic system 170, and the hydraulic actuator 111 (hydraulic cylinder 113) according to the third embodiment provides the same effects as those of the first embodiment.

Furthermore, the independent metering valve 171 of the hydraulic system 170 according to the third embodiment has a first shortcut recess 174a in the first meter-in spool 174 and a second shortcut recess 175a in the second meter-in spool 175. As a result, according to the drive control method for the independent metering valve 171, the hydraulic system 170, and the hydraulic actuator 111 (hydraulic cylinder 113), as described above, the pressure loss of the hydraulic oil flowing into the hydraulic cylinder 113 can be reduced, and the flow rate of the hydraulic oil discharged from the hydraulic cylinder 113 can be increased.

[Fourth embodiment]
<Independent metering valve>
11 is an explanatory diagram showing an example of a hydraulic system (an example of a fluid system in the claims) 180 when an arm 105 (see FIG. 1) is held stationary by an independent metering valve (an example of a control valve in the claims) 181 of the fourth embodiment. FIG. 11 corresponds to an explanatory diagram showing how the piston rod 118 of the hydraulic cylinder 116 is held stationary.
1 and 11, the independent metering valve 181 of the fourth embodiment is a valve that controls a hydraulic cylinder (an example of an actuator in the claims) 116 that drives the arm 105 of the construction machine 100. Note that the hydraulic cylinder 116 that operates the arm 105 is generally disposed, for example, in the vicinity of the arm 105, but in FIG. 1, the hydraulic cylinder 116 will be described as being disposed in the same position as the hydraulic cylinder 113 of the boom 104 for the sake of convenience.

As shown in FIG. 11 , the hydraulic cylinder 116 has a cylinder 117 , a piston rod 118 provided in the cylinder 117 so as to be slidable therein, and a head port Hp and a rod port Rp provided in the cylinder 117 .
The head port Hp is provided in a portion 117a of the cylinder 117 on the cylinder head side. The rod port Rp is provided in a portion 117b of the cylinder 117 on the piston rod 118 side.

The independent metering valve 181 includes a valve body (an example of a block body in the claims) 183, a first meter-in spool 184, a second meter-in spool 185, and a meter-out spool 186. The other configuration of the independent metering valve 181 is the same as that of the independent metering valve 171 of the third embodiment.

The valve body 183 has the same configuration as the valve body 173 of the third embodiment, and the components thereof will be described with the same reference numerals as those of the valve body 173.
The meter-out spool 186 is formed in the same manner as the meter-out spool 15 of the first embodiment. In the following, the components of the meter-out spool 186 will be described with the same reference numerals as those of the meter-out spool 15 of the first embodiment.

The first meter-in spool 184 has a first shortcut recess 184a (an example of a recess in the claims) instead of the first shortcut recess 174a of the first meter-in spool 174 of the third embodiment. Other configurations of the first meter-in spool 184 are the same as those of the first meter-in spool 174.
The first shortcut recess 184a is formed, for example, by a step recessed all around the first land 184b. Alternatively, the first shortcut recess 184a may be formed, for example, by a step and a notch.
The first shortcut recess 184a is formed on one side of one end of the bridge passage 30. The first shortcut recess 184a is disposed between the first rod passage 31 and the second rod passage 32 when the first meter-in spool 184 is disposed in the first neutral position (the position shown in FIG. 11 ).

12 is an explanatory diagram showing an example of an operation when the arm 105 is pushed by the hydraulic system 180 of the fourth embodiment. FIG. 12 corresponds to an explanatory diagram of the action of the piston rod 118 of the hydraulic cylinder 116 being retracted into the cylinder 117.
12 , when the first meter-in spool 184 is located at the first supply position (the position shown in FIG. 12 ), a part of the other side of the first shortcut recess 184a communicates with the bridge channel 30. At this time, a part of one side of the first shortcut recess 184a is located (interposed) between the first rod channel 31 and the second rod channel 32.
Therefore, the first shortcut recess 184a connects the bridge channel 30 to the first rod channel 31. As a result, the bridge channel 30 connects to the rod port Rp (specifically, the rod end side of the cylinder 117) via the first shortcut recess 184a, the first rod channel 31, and the rod-side channel 133.

When the meter-out spool 186 is positioned in the second discharge position (the position shown in FIG. 12), the bridge flow passage 30 communicates with the second rod flow passage 32 via the first notched flow passage 21 and the first discharge port D1. The second rod flow passage 32 communicates with the rod port Rp via the first rod flow passage 31 and the rod side flow passage 133. That is, when the meter-out spool 186 is positioned in the second discharge position, the bridge flow passage 30 communicates with the rod port Hp (specifically, the rod end side of the cylinder 117) via the first notched flow passage 21.

The second meter-in spool 185 has a second shortcut recess 185a (an example of another recess in the claims) instead of the second shortcut recess 175a of the second meter-in spool 175 of the third embodiment. Other configurations of the second meter-in spool 185 are the same as those of the second meter-in spool 175. The second shortcut recess 175a is formed, for example, by a step recessed all around with respect to the second land 185b. Note that the second shortcut recess 185a may be formed, for example, by a step and a notch.
The second shortcut recess 185a is formed on the other side of the other end of the bridge flow passage 30. The second shortcut recess 185a communicates with the fourth tank port T4 when the second meter-in spool 185 is disposed in the second neutral position (the position shown in FIG. 11 ).

12, when the second meter-in spool 185 is located at the second supply position (the position shown in FIG. 12), a portion of one side of the second shortcut recess 185a is located (interposed) between the first head flow path 33 and the second head flow path 34. At this time, a portion of the other side of the first shortcut recess 184a communicates with the fourth tank port T4.
Therefore, the second shortcut recess 185a connects the first head flow passage 33 to the fourth tank port T4. As a result, the head port Hp (specifically, the cylinder head side of the cylinder 117) connects to the tank 120 via the head-side flow passage 134, the first head flow passage 33, the second shortcut recess 185a, the fourth tank port T4, and the fifth discharge flow passage 178.

When the meter-out spool 186 is positioned at the second discharge position (the position shown in FIG. 12), the head port Hp communicates with the second head flow path 34 via the head side flow path 134 and the first head flow path 33. Furthermore, the second head flow path 34 communicates with the tank 120 via the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136. That is, the head port Rp (specifically, the cylinder head side of the cylinder 117) communicates with the tank 120 via the second notched flow path 22 of the meter-out spool 186 when the meter-out spool 186 is positioned at the second discharge position.

<Method of controlling hydraulic actuator drive using independent metering valve and hydraulic system>
Next, a method of controlling the drive of the hydraulic actuator 111 by the independent metering valve 181 and the hydraulic system 180 will be described with reference to FIGS.
First, an example in which the arm 105 (see FIG. 1) of the construction machine 100 is held stationary by an independent metering valve 181 will be described with reference to FIG.
11 , the first meter-in spool 184 is placed in a first neutral position, and the first pump port P1 and the first supply port S1 are blocked by the first meter-in spool 184. Also, the second meter-in spool 185 is placed in a second neutral position, and the second pump port P2 and the second supply port S2 are blocked by the second meter-in spool 185.

Furthermore, the meter-out spool 186 is placed in the central position (the position shown in FIG. 11) so that the meter-out spool 186 closes the first tank port T1 and the first drain port D1, and also closes the second tank port T2 and the second drain port D2.
In this state, the hydraulic oil discharged from each discharge port of the first pump 110A and the second pump 110B is returned to the tank 120, for example, via a return circuit not shown, and the arm 105 (see FIG. 1) is maintained in a stationary state.

Next, an example in which the arm 105 is pushed by the independent metering valve 181 will be described with reference to FIG.
As shown in FIG. 12, the first meter-in spool 184 is moved in the direction of arrow A12 to the first supply position, thereby establishing communication between the first pump port P1 and the first supply port S1 in the first meter-in passage 11.
Furthermore, by disposing the first meter-in spool 184 at the first supply position, the bridge flow passage 30 and the first rod flow passage 31 are communicated with each other through the first shortcut recess 184a. As a result, the rod port Rp is communicated with the bridge flow passage 30 via the first shortcut recess 184a, the first rod flow passage 31, the rod side flow passage 133, etc.

Furthermore, by moving the second meter-in spool 185 in the direction of arrow A13 to the second supply position, the second pump port P2 and the second supply port S2 are communicated with each other through the second meter-in flow path 12. As a result, the first pump port P1 and the second pump port P2 are communicated with the bridge flow path 30 via the first supply port S1 and the second supply port S2, etc., respectively.
Furthermore, by disposing the second meter-in spool 6 in the second supply position, the first head flow path 33 and the fourth tank port T4 communicate with each other through the second shortcut recess 185a. As a result, the fourth tank port T4 communicates with the head port Hp via the second shortcut recess 185a, the first head flow path 33, the head side flow path 134, etc.

Moreover, the meter-out spool 186 is moved in the direction of arrow A14 to be disposed at the second discharge position. By disposing the meter-out spool 186 at the second discharge position, the first notched flow passage 21 is communicated with the bridge flow passage 30 and also communicated with the rod port Rp via the first discharge port D1, etc. Specifically, the rod port Rp is communicated with the bridge flow passage 30 via the first notched flow passage 21, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, etc.
In addition, the first tank port T1 is blocked by the meter-out spool 186 disposed in the second discharge position.

Furthermore, by placing the meter-out spool 186 in the second discharge position, the second discharge port D2 and the second tank port T2 are connected by the second notched flow path 22. As a result, the second tank port T2 is connected to the head port Hp via the second notched flow path 22, the second discharge port D2, the second head flow path 34, the first head flow path 33, the head side flow path 134, etc.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V21 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. The hydraulic oil discharged from the discharge port of the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V22 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join in the bridge flow passage 30.

A portion of the joined hydraulic oil is guided to the first rod flow passage 31 as indicated by arrow V23 through the first shortcut recess 184a. The remainder of the joined hydraulic oil is guided to the first rod flow passage 31 as indicated by arrow V24 through the first notched flow passage 21, the first discharge port D1, and the second rod flow passage 32. Hereinafter, the portion of the joined hydraulic oil is referred to as the "first hydraulic oil" and the remainder of the joined hydraulic oil is referred to as the "second hydraulic oil."
The first and second hydraulic oils guided to the first rod flow passage 31 flow through the rod side flow passage 133 and the rod port Rp into the rod end side of the cylinder 117 as indicated by arrow V25.

In this way, the first hydraulic oil among the hydraulic oils merged in the bridge flow passage 30 can be guided to the first rod flow passage 31 via the first shortcut recess 184a without passing through the first notched flow passage 21 of the meter-out spool 186. This reduces the pressure loss of the hydraulic oil supplied from the bridge flow passage 30 to the rod end side of the cylinder 117. In other words, the hydraulic oil can be efficiently supplied to the rod end side of the cylinder 117.

On the other hand, the hydraulic oil on the cylinder head side of the cylinder 117 is guided to the first head flow path 33 as indicated by arrow V26 via the head port Hp and the head side flow path 134. A part of the hydraulic oil guided to the first head flow path 33 is discharged (returned) to the tank 120 as indicated by arrow V27 via the second shortcut recess 185a and the fifth discharge flow path 178.
The remainder of the hydraulic oil guided to the first head flow path 33 is discharged (returned) as indicated by arrow V28 to the tank 120 via the second head flow path 34, the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136. Hereinafter, the part of the hydraulic oil guided to the first head flow path 33 will be referred to as the "third hydraulic oil" and the remainder of the guided hydraulic oil will be referred to as the "fourth hydraulic oil."

In this way, the third hydraulic oil among the hydraulic oil guided to the first head flow path 33 can be guided to the tank 120 via the second shortcut recess 185a without passing through the second notched flow path 22 of the meter-out spool 186. This increases the flow rate of hydraulic oil returning from the cylinder head side of the cylinder 117 to the tank 120, allowing the hydraulic oil to be efficiently returned from the cylinder head side to the tank 120.

By supplying hydraulic oil to the rod end side of the cylinder 117 and returning the hydraulic oil from the cylinder head side to the tank 120, the piston rod 118 is pulled into the cylinder 117 as shown by arrow E6, and the arm 105 (see Figure 1) is pushed.

As described above, similar to the first embodiment, the independent metering valve 181 of the hydraulic system 180 according to the fourth embodiment includes two independent meter-in spools, the first meter-in spool 184 and the second meter-in spool 185. As a result, according to the independent metering valve 181, the hydraulic system 180, and the drive control method for the hydraulic actuator 111, when the arm 105 is pressed, the flow rate of the hydraulic oil flowing into the rod end side of the cylinder 117 can be highly efficiently adjusted, similar to the first embodiment.
Furthermore, the method of controlling the drive of the independent metering valve 181, the hydraulic system 180, and the hydraulic actuator 111 according to the fourth embodiment achieves the same effects as those of the first embodiment.

Furthermore, the independent metering valve 181 of the hydraulic system 180 according to the fourth embodiment has a first shortcut recess 184a in the first meter-in spool 184 and a second shortcut recess in the second meter-in spool 185. As a result, according to the drive control method for the independent metering valve 181, the hydraulic system 180, and the hydraulic actuator 111, as described above, the pressure loss of the hydraulic oil flowing into the hydraulic cylinder 116 can be reduced, and the flow rate of the hydraulic oil discharged from the hydraulic cylinder 116 can be increased.

[Fifth embodiment]
<Independent metering valve>
13 is an explanatory diagram showing an example of a hydraulic system (an example of a fluid system in the claims) 190 when the arm 105 (see FIG. 1) is held stationary by an independent metering valve (an example of a control valve in the claims) 191 of the fifth embodiment. FIG. 13 corresponds to an explanatory diagram showing how the piston rod 118 of the hydraulic cylinder 116 is held stationary.
As shown in FIGS. 1 and 13 , the independent metering valve 191 of the fifth embodiment is a valve that controls the hydraulic cylinder 116 that drives the arm 105 of the construction machine 100 .
The independent metering valve 191 includes a valve body (an example of a block body in the claims) 193, a first meter-in spool 194, a second meter-in spool 195, and a meter-out spool 196. Other configurations of the independent metering valve 191 are similar to those of the independent metering valve 181 of the fourth embodiment.

The valve body 193 has a bypass flow passage 197 having a U-shaped cross section along the axial direction, a third check valve 198 provided in the middle of the bypass flow passage 197, and a bypass port G2. Other configurations of the valve body 193 are similar to those of the valve body 183 of the fourth embodiment. Below, each component of the valve body 193 will be described using the same reference numerals as those of the valve body 183 of the fourth embodiment.
The bypass flow passage 197 communicates the first notched flow passage 21 with the bypass port G2 via a third check valve 198. The bypass port G2 is disposed axially inward of a third notched flow passage 199, which will be described later, when the meter-out spool 196 is disposed in the central position (the position shown in FIG. 13).

The first meter-in spool 194 is obtained by removing the first shortcut recess 184a from the first meter-in spool 184 of the fourth embodiment, and the first pump port P1 is formed on one end side (outside) in the axial direction relative to the first supply port S1.
The second meter-in spool 195 is obtained by removing the second shortcut recess 185a from the second meter-in spool 185 of the fourth embodiment, and the second pump port P2 is formed on the other axial end side (outward) of the second supply port S2.

A third notched flow passage 199 is formed in the meter-out spool 196. Other configurations of the meter-out spool 196 are formed similarly to the meter-out spool 186 of the fourth embodiment. Hereinafter, each configuration of the meter-out spool 196 will be described with the same reference numerals as those of the meter-out spool 186 of the fourth embodiment.
The third notched passage 199 is formed axially inward from the second notched passage 22. When the meter-out spool 196 is disposed at the central position, the third notched passage 199 is disposed axially outward from the bypass port G2 and communicates with the connection port G3. The connection port G3 communicates with the other end of the bridge passage 30.

14 is an explanatory diagram showing an example of movement when the arm 105 (see FIG. 1) is pulled by the hydraulic system 190 of the fifth embodiment. FIG. 14 corresponds to an explanatory diagram of the action of pushing out the piston rod 118 of the hydraulic cylinder 116.
As shown in FIG. 14, when the meter-out spool 196 is disposed in the regeneration position (the position shown in FIG. 14), the third notched flow passage 199 communicates with the bypass port G2 while communicating with the connection port G3.

15 is an explanatory diagram showing an example of excavation when the arm 105 is pulled by the hydraulic system 190 of the fifth embodiment.
As shown in FIG. 15, when the meter-out spool 196 is positioned in the first discharge position (the position shown in FIG. 15), the third notched flow passage 199 is positioned axially inward from the connection port G3 and communicates with the bypass port G2.

16 is an explanatory diagram showing an example of an operation when the arm 105 is pushed by the hydraulic system 190 of the fifth embodiment. FIG. 16 corresponds to an explanatory diagram of the action of the piston rod 118 of the hydraulic cylinder 116 being retracted into the cylinder 117.
As shown in FIG. 16, when the meter-out spool 196 is positioned in the second discharge position (the position shown in FIG. 16), the third notched flow passage 199 is positioned axially outward from the bypass port G2 and in communication with the connection port G3.

<Method of controlling hydraulic actuator drive using independent metering valve and hydraulic system>
Next, a method of controlling the drive of the independent metering valve 191 and the hydraulic actuator 111 of the hydraulic system 190 will be described with reference to FIGS.
First, an example in which the arm 105 (see FIG. 1) of the construction machine 100 is held stationary by an independent metering valve 191 will be described with reference to FIG.
13, the first meter-in spool 194 is placed in a first neutral position (the position shown in FIG. 13) and the first pump port P1 and the first supply port S1 are blocked by the first meter-in spool 194. The second meter-in spool 195 is placed in a second neutral position (the position shown in FIG. 13) and the second pump port P2 and the second supply port S2 are blocked by the second meter-in spool 195.

Furthermore, the meter-out spool 196 is disposed in a central position so as to close the first tank port T1 and the first discharge port D1, and also close the second tank port T2 and the second discharge port D2.
In this state, the hydraulic oil discharged from each discharge port of the first pump 110A and the second pump 110B is returned to the tank 120, for example, via a return circuit not shown, and the arm 105 (see FIG. 1) is maintained in a stationary state.

Next, an example of movement when the arm 105 is pulled by the independent metering valve 191 will be described with reference to Fig. 14. Note that the movement when the arm 105 is pulled refers to the operation when the arm 105 is pulled in a state where the bucket 106 (see Fig. 1) is not excavating soil or the like.
As shown in FIG. 14, by moving the first meter-in spool 194 in the direction of arrow A15 and placing it in the first supply position (the position shown in FIG. 14), the first pump port P1 and the first supply port S1 are connected via the first meter-in flow path 11.
Furthermore, by moving the second meter-in spool 195 in the direction of arrow A16 to the second supply position (the position shown in FIG. 14), the second pump port P2 and the second supply port S2 are communicated with each other through the second meter-in flow path 12. As a result, the first pump port P1 and the second pump port P2 communicate with the bridge flow path 30 via the first supply port S1 and the second supply port S2, etc., respectively.

The meter-out spool 196 is then moved in the direction of arrow A17 to the regeneration position. By placing the meter-out spool 196 in the regeneration position, the second notched flow path 22 is connected to the bridge flow path 30 and also to the head port Hp via the second exhaust port D2, etc. Specifically, the head port Hp is connected to the bridge flow path 30 via the connection port G3, the second notched flow path 22, the second exhaust port D2, the second head flow path 34, the first head flow path 33, and the head side flow path 134, etc.

Moreover, by disposing the meter-out spool 196 in the regeneration position, the third notched flow passage 199 is communicated with the second notched flow passage 22 and also communicated with the rod port Rp via the bypass port G2, etc. Specifically, the rod port Rp is communicated with the second notched flow passage 22 via the connection port G3, the third notched flow passage 199, the bypass port G2, the bypass flow passage 197, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, etc.
Furthermore, the first tank port T1 and the second tank port T2 are blocked by the meter-out spool 196 placed in the regeneration position.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided as indicated by arrow V30 to the bridge flow passage 30 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. Also, the hydraulic oil discharged from the discharge port of the second pump 110B is guided as indicated by arrow V31 to the bridge flow passage 30 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join together in the bridge flow passage 30.
The joined hydraulic oil passes through the second notched passage 22, the second discharge port D2, and the second head passage 34, and is guided to the first head passage 33 as indicated by the arrow V32. The hydraulic oil guided to the first rod passage 31 passes through the head side passage 134 and the head port Hp, and flows into the cylinder head side of the cylinder 117 as indicated by the arrow V33.

On the other hand, the hydraulic oil on the rod end side of the cylinder 117 is guided as indicated by an arrow V34 to the bypass flow path 197 via the rod port Rp, the rod-side flow path 133, the first rod flow path 31, and the second rod flow path 32. The hydraulic oil guided to the bypass flow path 197 flows into the second notched flow path 22 as indicated by an arrow V34 via a third check valve 198, a bypass port G2, a third notched flow path 199, a connection port G3, and the like.
The hydraulic oil guided to the second notched passage 22 is guided to the first head passage 33 via the second discharge port D2 and the second head passage 34. The hydraulic oil guided to the first head passage 33 flows into the cylinder head side of the cylinder 117 via the head side passage 134 and the head port Hp.

In this way, when the arm 105 is pulled to move, the rod port Rp of the cylinder 117 is connected to the head port Hp, and the hydraulic oil on the rod end side of the cylinder 117 can be regenerated by flowing into the cylinder head side.
By reproducing the operation of the rod end side, the piston rod 118 can be pushed out from the cylinder 117 quickly with little energy as shown by the arrow E7. This allows the movement of the arm 105 when pulled to be operated quickly with little energy, thereby increasing the movement of the arm 105 and saving energy.

Next, an example of excavation by pulling the arm 105 with the independent metering valve 191 will be described with reference to Fig. 15. Excavation by pulling the arm 105 refers to an operation of excavating soil or the like with the bucket 106 (see Fig. 1) while pulling the arm 105.
15, the first meter-in spool 194 and the second meter-in spool 195 are held in the first supply position and the second supply position, respectively, similar to the example of movement when the arm 105 is pulled. In this state, the meter-out spool 196 is moved in the direction of arrow A18 from the regeneration position (position shown in FIG. 14) to be placed in the first discharge position (position shown in FIG. 15). The second notched flow passage 22 is maintained in a state in which it communicates with the bridge flow passage 30 and communicates with the head port Hp via the second discharge port D2 etc., similar to when the meter-out spool 196 is placed in the regeneration position.

Furthermore, by placing the meter-out spool 196 in the first discharge position, the third notched passage 199 is maintained in a closed state relative to the second discharge port D2.
Furthermore, by disposing the meter-out spool 196 in the first discharge position, the first discharge port D1 and the first tank port T1 communicate with each other through the first notched flow path 21. As a result, the first tank port T1 communicates with the rod port Rp via the first notched flow path 21, the first discharge port D1, the second rod flow path 32, the first rod flow path 31, the rod side flow path 133, and the like.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided as indicated by arrow V30 to the bridge flow passage 30 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. Also, the hydraulic oil discharged from the discharge port of the second pump 110B is guided as indicated by arrow V31 to the bridge flow passage 30 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join together in the bridge flow passage 30.
The joined hydraulic oil passes through the second notched passage 22, the second discharge port D2, and the second head passage 34, and is guided to the first head passage 33 as indicated by the arrow V32. The hydraulic oil guided to the first rod passage 31 passes through the head side passage 134 and the head port Hp, and flows into the cylinder head side of the cylinder 117 as indicated by the arrow V33.

On the other hand, hydraulic oil on the rod end side of the cylinder 117 is guided to the first discharge port D1 as indicated by arrow V35 via the rod port Rp, the rod side flow path 133, the first rod flow path 31, and the second rod flow path 32. The hydraulic oil guided to the first discharge port D1 is discharged (returned) to the tank 120 as indicated by arrow V35 via the first notched flow path 21, the first tank port T1, and the first discharge flow path 135.

In this way, when excavating with the bucket 106 while pulling the arm 105 , the hydraulic oil on the rod end side of the cylinder 117 can be returned to the tank 120 from the rod port Rp.
Therefore, the piston rod 118 can be pushed out from the cylinder 117 as shown by arrow E7 by the hydraulic oil discharged from each discharge port of the first pump 110A and the second pump 110B. As a result, when excavating with the bucket 106 while pulling the arm 105, the excavation force of the bucket 106 can be secured, and excavation work can be efficiently performed by the construction machine 100 (see FIG. 1 ).

Next, an example in which the arm 105 is pushed by an independent metering valve 191 will be described with reference to FIG.
16, the first meter-in spool 194 and the second meter-in spool 195 are held in the first supply position and the second supply position, respectively, in the same manner as when the arm 105 is pulled. In this state, the meter-out spool 196 is moved in the direction of arrow A19 to be disposed in the second discharge position (the position shown in FIG. 16).
By disposing the meter-out spool 196 at the second discharge position, the first notched flow passage 21 is communicated with the bridge flow passage 30 and also communicated with the rod port Rp via the first discharge port D1, etc. Specifically, the rod port Rp is communicated with the bridge flow passage 30 via the first notched flow passage 21, the first discharge port D1, the second rod flow passage 32, the first rod flow passage 31, the rod side flow passage 133, etc.
Furthermore, the first tank port T1 is blocked by the meter-out spool 196 disposed in the second discharge position.

In addition, by placing the meter-out spool 126 in the second discharge position, the second discharge port D2 and the second tank port T2 are connected by the second notched flow path 22. As a result, the second tank port T2 is connected to the head port Hp via the second notched flow path 22, the second discharge port D2, the second head flow path 34, the first head flow path 33, the head side flow path 134, etc.

In this state, the hydraulic oil discharged from the discharge port of the first pump 110A is guided to the bridge flow passage 30 as indicated by arrow V30 via the first pump port P1, the first meter-in flow passage 11, the first supply port S1, and the first check valve 41. The hydraulic oil discharged from the discharge port of the second pump 110B is guided to the bridge flow passage 30 as indicated by arrow V31 via the second pump port P2, the second meter-in flow passage 12, the second supply port S2, and the second check valve 42. Therefore, the hydraulic oil discharged from the first pump 110A and the second pump 110B join in the bridge flow passage 30.

The combined hydraulic oil is guided to the first rod flow path 31 as indicated by arrow V36 via the first notched flow path 21, the first discharge port D1, and the second rod flow path 32. The hydraulic oil guided to the first rod flow path 31 flows into the rod end side of the cylinder 117 as indicated by arrow V36 via the rod side flow path 133 and the rod port Rp.

On the other hand, the hydraulic oil on the cylinder head side of the cylinder 117 is guided as indicated by the arrow V37 to the first head flow path 33 via the head port Hp and the head side flow path 134. The hydraulic oil guided to the first head flow path 33 is discharged (returned) to the tank 120 as indicated by the arrow V37 via the second head flow path 34, the second discharge port D2, the second notched flow path 22, the second tank port T2, and the second discharge flow path 136.
In this manner, by supplying hydraulic oil to the rod end side of the cylinder 117 and returning the hydraulic oil from the cylinder head side to the tank 120, the piston rod 118 is drawn into the cylinder 117 as indicated by arrow E8, and the arm 105 (see FIG. 1) is pushed.

As described above, the independent metering valve 191 of the hydraulic system 190 according to the fifth embodiment, like the fourth embodiment, is provided with two independent meter-in spools, the first meter-in spool 194 and the second meter-in spool 195. As a result, according to the independent metering valve 191, the hydraulic system 190, and the drive control method for the hydraulic actuator 111, like the first embodiment, the flow rate of the hydraulic oil flowing into the head end side of the cylinder 117 can be highly efficiently adjusted when moving while pulling the arm 105 or when excavating.
Furthermore, according to the independent metering valve 191, the hydraulic system 190, and the drive control method of the hydraulic actuator 111, when the arm 105 is pushed, the flow rate of the hydraulic oil flowing into the rod end side of the cylinder 117 can be highly accurately adjusted, as in the first embodiment.
In addition, the method of controlling the drive of the independent metering valve 191, the hydraulic system 190, and the hydraulic actuator 111 according to the fifth embodiment achieves the same effects as the first embodiment.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the construction machine 100 is a hydraulic excavator, but the present invention is not limited to this. For example, the present invention may be applied to construction machines other than hydraulic excavators, such as hydraulic cranes.

In the above-described embodiment, an example was given in which the fluid system is a hydraulic system equipped with a hydraulic control device, but this is not limited thereto. For example, the fluid system may be equipped with a fluid control device other than a hydraulic control device, such as an air pressure control device or a water pressure control device.

In the above-described embodiment, the hydraulic cylinders 113 and 116 are used as actuators, but this is not limiting. For example, the present invention may be applied to actuators such as hydraulic motors.

In the above embodiment, the solenoid proportional valves 7, 8, 16, and 17 have been described as examples of the solenoid valves, but this is not limiting. For example, the present invention may be applied to various solenoid valves that are driven based on electrical signals. Alternatively, instead of the solenoid proportional valves 7, 8, 16, and 17, the first meter-in spool 5, 153, 174, 184, and 194, the second meter-in spool 6, 154, 175, 185, and 195, and the meter-out spools 15, 186, and 196 may be controlled by hydraulic pilot pressure.

In addition, the components of the above-described embodiment may be replaced with well-known components without departing from the spirit of the present invention. Also, the above-described modified examples may be combined.
For example, in the above-described embodiments, hydraulic systems 109, 150, 170, 180, and 190 using hydraulic oil as the fluid system have been described. However, the present invention is not limited to this, and the configurations of the above-described embodiments can be applied to fluid systems using various fluids. Examples of fluid systems include systems that use water or air as the fluid instead of hydraulic oil.

In the above embodiment, the first spool hole 10 has been described as an example of the meter-in spool housing that houses the first meter-in spool 5 and the second meter-in spool 6. However, the structure of the meter-in spool housing is not limited to a hole. The meter-in spool housing may have any structure that has a space that can house the first meter-in spool 5 and the second meter-in spool 6.

2,151,171,181,191...Independent metering valve (control valve), 3,173,183,193...Valve body (block body), 5,153,174,184,194...First meter-in spool, 6,154,175,185,195...Second meter-in spool, 10...First spool hole (meter-in spool housing), 11...First meter-in flow path, 12...Second meter-in flow path, 13...Intermediate portion, 15,186,196...Meter-out spool, 21,22...First and second notched flow paths (flow paths), 30...B Ridge flow path (supply flow path), 100...construction machine, 109, 150, 170, 180, 190...hydraulic system (fluid system), 110A...first pump, 110B...second pump, 111...hydraulic actuator (actuator), 113, 116...hydraulic cylinder (actuator), 120...tank, 153a, 174a, 184a...first shortcut recess (recess), 154a, 175a, 185a...second shortcut recess (other recess), Hp...head port (supply/discharge port), Rp...rod port (supply/discharge port)

Claims (7)

a first meter-in spool having a first meter-in passage communicating with a first pump;
a second meter-in spool having a second meter-in passage communicating with the second pump;
a supply passage communicating with the first meter-in passage and the second meter-in passage and communicating with a supply/discharge port of an actuator;
a meter-in spool housing portion that collectively houses the first meter-in spool and the second meter-in spool;
Equipped with
The meter-in spool accommodating portion is provided between the first meter-in spool and the second meter-in spool so as to face each other in the axial direction of the meter-in spool, and has an intermediate portion which communicates with a tank.
Control valve. 2. The control valve of claim 1, further comprising a meter-out spool having passages leading to the supply passage and to the supply and exhaust ports of the actuator. a first meter-in spool having a first meter-in passage communicating with a first pump;
a second meter-in spool having a second meter-in passage communicating with the second pump;
a supply passage communicating with the first meter-in passage and the second meter-in passage and communicating with a supply/discharge port of an actuator;
a meter-out spool having a flow path communicating with the supply flow path and the supply/discharge port of the actuator;
Equipped with
The first meter-in spool has a recess that connects the supply passage to the supply/discharge port of the actuator or connects the supply/discharge port of the actuator to a tank.
Control valve. 4. The control valve according to claim 3 , wherein the second meter-in spool has another recess that connects the supply passage to the supply/discharge port of the actuator or connects the supply/discharge port of the actuator to a tank. 5. The control valve according to claim 3, further comprising a block body which collectively accommodates the first meter-in spool, the second meter-in spool, and the meter-out spool. a first meter-in spool having a first meter-in passage communicating with a first pump;
a second meter-in spool having a second meter-in passage communicating with the second pump;
a supply passage communicating with the first meter-in passage and the second meter-in passage and communicating with a supply/discharge port of an actuator;
a meter-out spool having a flow path communicating with the supply flow path and the supply/discharge port of the actuator;
a block body that collectively accommodates the first meter-in spool, the second meter-in spool, and the meter-out spool;
a meter-in spool accommodating portion provided in the block body to collectively accommodate the first meter-in spool and the second meter-in spool, the meter-in spool accommodating portion having an intermediate portion communicating with a tank between the first meter-in spool and the second meter-in spool which face each other in the axial direction of the meter-in spool;
A control valve comprising: a first meter-in spool having a first meter-in passage communicating with a first pump;
a second meter-in spool having a second meter-in passage communicating with the second pump;
a supply passage communicating with the first meter-in passage and the second meter-in passage and communicating with a supply/discharge port of an actuator;
a meter-out spool having a flow path communicating with the supply flow path and the supply/discharge port of the actuator;
a block body that collectively accommodates the first meter-in spool, the second meter-in spool, and the meter-out spool;
a meter-in spool accommodating portion provided in the block body to collectively accommodate the first meter-in spool and the second meter-in spool, the meter-in spool accommodating portion having an intermediate portion communicating with a tank between the first meter-in spool and the second meter-in spool which face each other in the axial direction of the meter-in spool;
Equipped with
the first meter-in spool has a recess that connects the supply passage to the supply/discharge port of the actuator or connects the supply/discharge port of the actuator to a tank,
The second meter-in spool is a control valve having another recess that connects the supply passage to the supply/discharge port of the actuator, or connects the supply/discharge port of the actuator to a tank.

Images