JP7613863B2 - Fluid valve, fluid system, and construction machine - Google Patents

Description

The present invention relates to a fluid valve, a fluid system, and a construction machine.

For example, construction machinery such as hydraulic excavators is driven and controlled by a hydraulic system that has a hydraulic actuator. For example, the hydraulic actuator is driven and controlled by hydraulic oil discharged from a pump (hydraulic pump). For example, in Patent Document 1, when hydraulic oil is supplied to the cylinder head side of the cylinder, the hydraulic oil on the cylinder rod side is returned to the tank.

JP 2004-360751 A

In this way, the construction machine keeps the hydraulic oil on the cylinder rod side returning to the tank, for example, from before the excavation position is reached until excavation is completed. There is a demand for practical application of technology that can further improve the operability of hydraulic actuators and achieve further energy savings in this type of construction machine.

The present invention provides a fluid valve, a fluid system, and a construction machine that improve the operability of an actuator, saves energy, and enables the actuator to perform operations such as excavation.

A fluid valve according to one aspect of the present invention comprises a valve body having a supply/discharge port connected to either a discharge port or a cylinder port provided in an actuator driven by a fluid, and a tank port connected to a tank passage, and a meter-out spool movably provided within a sleeve hole formed in the valve body and controlling the amount of fluid discharged from the actuator, and the meter-out spool connects the discharge port to either only the cylinder port, only the tank passage that discharges the fluid, or both the cylinder port and the tank passage.

With this configuration, the movement of the meter-out spool connects the discharge port to at least one of the cylinder port and the tank passage that discharges the fluid. For example, when supplying fluid to the cylinder head side of the cylinder, the discharge port of the cylinder (i.e., the rod port) is connected to the cylinder port. This allows the fluid on the rod end side of the cylinder to be regenerated by flowing it to the head end side. By regenerating the fluid on the rod end side, the piston rod can be protruded from the cylinder quickly with little energy. This improves the operability of the actuator and saves energy.

In addition, when performing work such as excavation using the actuator, the discharge port (rod port) is connected to the tank passage in the same way as in a normal cylinder. Therefore, the piston rod can be protruded from the cylinder only by the fluid discharged from the pump. This allows the actuator to perform work such as excavation.
Furthermore, by connecting the cylinder port and the tank passage to each other, the flow rate of the fluid flowing from the rod end to the head end of the cylinder can be adjusted. This makes it possible to adjust the flow rate of the fluid with a simple structure according to the application of the actuator, and also to achieve energy savings.

In the above configuration, the meter-out spool may adjust the flow rate of the fluid from the discharge port to either only the cylinder port, only the tank passage, or both the cylinder port and the tank passage by moving the meter-out spool.

In the above configuration, the meter-out spool may have a notch that blocks the flow path of the cylinder port or the tank passage, or adjusts the flow rate of the fluid flowing through the flow path.

In the above configuration, the meter-out spool may have a land that blocks the flow path of the cylinder port or the tank passage, or adjusts the flow rate of the fluid flowing through the flow path.

A fluid system according to another aspect of the present invention includes a fluid valve and an actuator driven by a fluid whose flow rate is adjusted by the fluid valve. The fluid valve includes a valve body having a supply/discharge port connected to one of a discharge port or a cylinder port provided in the actuator driven by the fluid, and a tank port connected to a tank passage, and a meter-out spool movably provided in a sleeve hole formed in the valve body and controlling the amount of fluid discharged from the actuator. The meter-out spool connects the discharge port to only the cylinder port, only the tank passage for discharging the fluid, or both the cylinder port and the tank passage. The actuator includes a cylinder and a piston rod slidably provided in the cylinder, and includes a pressure sensor for detecting either the pressure in the cylinder or the discharge pressure of a pump that supplies the fluid to the cylinder port, and drives and controls the meter-out spool based on the detected pressure detected by the pressure sensor.

In this way, the meter-out spool can be driven and controlled based on the pressure detected by the pressure sensor, improving the actuator's operability and saving energy with a simple structure.

In the above configuration, the discharge port may be connected to the tank passage when the detected pressure is equal to or greater than a threshold, and the discharge port may be connected to the cylinder port when the detected pressure is less than the threshold.

The above configuration may include a solenoid valve that drives the meter-out spool based on an electrical signal.

The above configuration may include a control unit that controls the operation of the solenoid valve based on the detection signal of the pressure sensor.

A construction machine according to another aspect of the present invention includes a fluid valve and an arm drive actuator that is driven by a fluid whose flow rate is adjusted by the fluid valve and drives an arm. The fluid valve includes a valve body having a supply/discharge port connected to one of a discharge port or a cylinder port provided in the actuator driven by the fluid, and a tank port connected to a tank passage, and a meter-out spool that is movably provided in a sleeve hole formed in the valve body and controls the amount of fluid discharged from the actuator. The meter-out spool connects the discharge port to only the cylinder port, only the tank passage that discharges the fluid, or both the cylinder port and the tank passage. The actuator includes a cylinder and a piston rod that is slidably provided in the cylinder, and includes a pressure sensor that detects either the pressure in the cylinder or the discharge pressure of a pump that supplies the fluid to the cylinder port, and drives and controls the meter-out spool based on the detected pressure detected by the pressure sensor.

With this configuration, the movement of the meter-out spool connects the discharge port to at least one of the cylinder port and the tank passage that discharges the fluid. For example, when supplying fluid to the cylinder head side of the cylinder, the discharge port of the cylinder (i.e., the rod port) is connected to the cylinder port. This allows the fluid on the rod end side of the cylinder to be regenerated by flowing it to the head end side. By regenerating the fluid on the rod end side, the piston rod can be protruded from the cylinder quickly with little energy. This makes it possible to improve the workability of construction machinery with a simple structure and to achieve energy savings in construction machinery.

Furthermore, for example, when performing work such as excavation using the actuator, the piston rod can be protruded from the cylinder using only the fluid discharged from the pump, just like in a normal cylinder. This allows work such as excavation to be performed by the arm of a construction machine, for example.
Furthermore, by connecting to both the cylinder port and the tank passage, the flow rate of the fluid flowing from the rod end to the head end of the cylinder can be adjusted. This makes it possible to adjust the flow rate of the fluid with a simple configuration according to the application of the construction machine, for example, and to achieve energy savings.

A construction machine according to another aspect of the present invention includes an arm, an actuator that drives the arm with a fluid and has a cylinder and a piston rod that is slidably disposed within the cylinder, a meter-out spool that is connected to one of the discharge port and cylinder port of the actuator and controls the amount of fluid discharged from the actuator, a solenoid valve that drives the meter-out spool based on an electric signal, a pressure sensor that detects either the pressure in the cylinder or the discharge pressure of a pump that supplies the fluid to the cylinder port, and a control unit that drives the meter-out spool by controlling the drive of the solenoid valve based on a signal of the detected pressure detected by the pressure sensor. When the detected pressure is equal to or greater than a threshold value, the discharge port is connected to the tank passage, and when the detected pressure is less than the threshold value, the discharge port is connected to the cylinder port, or to the cylinder port and the tank passage.

With this configuration, when supplying fluid to the cylinder head side of the cylinder, the cylinder's discharge port (i.e., rod port) can be connected to the cylinder port. This allows the fluid on the rod end side of the cylinder to be regenerated by flowing it to the head end side. By using the fluid on the rod end side, the piston rod can be protruded from the cylinder quickly with little energy. This can improve the workability of the arm of a construction machine, for example, while also saving energy.

Furthermore, for example, when performing work such as excavation using the actuator, the piston rod can be protruded from the cylinder using only the fluid discharged from the pump, just like in a normal cylinder. This allows work such as excavation to be performed by the arm of a construction machine, for example.
Furthermore, by connecting to both the cylinder port and the tank passage, the flow rate of the fluid flowing from the rod end to the head end of the cylinder can be adjusted. This makes it possible to adjust the flow rate of the fluid with a simple configuration according to the application of the construction machine, for example, and to achieve energy savings.

A control method according to another aspect of the present invention includes a step of detecting, with a pressure sensor, either the pressure in a cylinder provided in an actuator or the discharge pressure of a pump that supplies fluid to a cylinder port of the actuator, and connecting the discharge port of the actuator to a tank passage that discharges the fluid when the detected pressure of the pressure sensor is equal to or greater than a threshold value, and connecting the discharge port to the cylinder port, or to the cylinder port and the tank passage, when the detected pressure of the pressure sensor is less than the threshold value.

By using this control method, when the pressure detected by the pressure sensor is equal to or greater than the threshold value, the discharge port is connected to the tank passage, and the piston rod can be protruded from the cylinder using only the fluid discharged from the pump, just like a normal cylinder. This allows the actuator (i.e. the arm of a construction machine) to perform tasks such as excavation.

On the other hand, when the pressure detected by the pressure sensor is below the threshold, the discharge port is connected to the cylinder port, and the fluid on the rod end side of the cylinder can be circulated to the head end side for regeneration. By using the fluid on the rod end side, the piston rod can be protruded from the cylinder quickly with little energy. This improves the workability of the actuator (i.e., the arm of the construction machine) and saves energy.
In addition, by connecting the discharge port to both the cylinder port and the tank passage when the pressure detected by the pressure sensor is below a threshold value, the flow rate of the fluid flowing from the rod end side to the head end side of the cylinder can be adjusted. This makes it possible to adjust the flow rate of the fluid with a simple configuration and to save energy depending on the application of the actuator, for example.

The present invention improves the operability of the actuator and saves energy, and allows the actuator to perform tasks such as excavation.

1 is a schematic diagram of a construction machine according to an embodiment of the present invention. 1 is a schematic diagram of a hydraulic system according to an embodiment of the present invention. 5A to 5C are diagrams illustrating an example of an operation of the hydraulic system when pulling an arm in the embodiment of the present invention. FIG. 4 is an explanatory diagram of an example of an operation of the hydraulic system when pushing an arm in the 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 (fluid 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.

<Construction machinery>
FIG. 1 is a schematic diagram of a construction machine 100 according to an embodiment.
As shown in Fig. 1, the construction machine 100 is, for example, a hydraulic excavator. The construction machine 100 includes a revolving body 101 and a running body 102. The revolving body 101 is provided on the running body 102 so as to be able to revolve. The revolving body 101 is equipped with a hydraulic pump 110 and a hydraulic control device (an example of a fluid control device) 1 that controls the flow rate of hydraulic oil (fluid) 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 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 a hydraulic system 109 according to an embodiment. Fig. 2 is a schematic diagram including a cross section of the hydraulic control device 1. Fig. 2 illustrates a state in which the meter-in spool 5 and the meter-out spool 15 according to the embodiment are located in a neutral position (second neutral position) Po4.
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 (an example of a pump in the claims) 110 that supplies hydraulic oil to the hydraulic control device 1, and a hydraulic actuator 111 that is driven and controlled by the hydraulic control device 1.

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 an arm driving cylinder that drives the arm 105 selected from the boom 104, the arm 105, and the bucket 106.

The hydraulic cylinder 113 has a cylinder 114, a piston rod 115 slidably provided within the cylinder 114, and a head port Hp (an example of a cylinder port in the claims) and a rod port Rp (an example of a discharge port in the claims) provided in the cylinder 114. The hydraulic cylinder 113 has the head port Hp and the rod port Rp as two supply and discharge ports.
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 by a prime mover (not shown). The hydraulic pump 110 varies the discharge amount of hydraulic oil 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 provided two hydraulic pumps 110. Hereinafter, one of the two hydraulic pumps 110 will be referred to as a "first pump 110A" and the other of the two hydraulic pumps 110 will be referred to as a "second pump 110B."

<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 fluid 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 arm 105 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 a hydraulic cylinder 113 that drives the arm 105 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 3, a round rod-shaped meter-in spool 5 housed in the valve body 3, and a first meter-in solenoid proportional valve 6 and a second meter-in solenoid proportional valve 7 which drive and control the meter-in spool 5.

The independent metering valve 2 is mainly composed of a rod-shaped meter-out spool 15 housed in the valve body 3, a first meter-out solenoid proportional valve (an example of the solenoid valve in the claims) 16 that drives and controls the meter-out spool 15, and a second meter-out solenoid proportional valve (an example of the solenoid valve in the claims) 17.

The independent metering valve 2 also includes a control unit 25 that controls the solenoid proportional valves 6, 7, 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.

Furthermore, the independent metering valve 2 includes a pressure sensor 26 that detects, for example, the internal pressure on the head end side of the cylinder 114 (an example of the pressure inside the cylinder in the claims; cylinder pressure). The pressure sensor 26 is connected midway through a head side flow path 134, which will be described later. Based on the pressure detected by the pressure sensor 26, the control unit 25 controls the first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17. The meter-out spool 15 is driven and controlled by controlling the solenoid proportional valves 16, 17.
In the embodiment, an example in which the cylinder pressure is detected by the pressure sensor 26 will be described, but the present invention is not limited to this. As another example, the pressure sensor may detect the discharge pressure (pump pressure) of the first pump 110A and the second pump 110B. Alternatively, the pressure sensor may be provided at the head end of the cylinder 114, and the cylinder pressure on the head end side may be directly detected by the pressure sensor.

The valve body 3 has a first sleeve hole (an example of a sleeve hole in the claims) 10 that houses the meter-in spool 5, 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 sleeve hole 10, a second sleeve hole (an example of a sleeve hole in the claims) 20 that houses the meter-out spool 15, and a first tank port T1, a second tank port (an example of a tank port in the claims) T2, a first exhaust port (an example of a supply and exhaust port in the claims) D1, and a second exhaust port (an example of a supply and exhaust port in the claims) D2 that open into the second sleeve hole 20.

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

The first sleeve hole 10 and the second sleeve hole 20 are formed along one direction of the valve body 3. The first sleeve hole 10 and the second sleeve hole 20 have a circular cross section along the axial direction. The first sleeve hole 10 and the second sleeve 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 sleeve hole 10, 20.

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.

The first tank port T1 is connected to the tank (an example of a tank in the claims) 120 via a first discharge flow path (an example of a tank passage in the claims) 135. The second tank port T2 is connected to the tank 120 via a second discharge flow path (an example of a tank passage in the claims) 136. The first discharge port D1 is connected to the head port Hp via the head flow paths 31, 32 and the head side flow path 134. The second discharge port D2 is connected to the rod port Rp via the rod flow paths 33, 34 and the rod side flow path 133.

Both ends of the bridge passage 30 are connected to the first sleeve hole 10. The bridge passage 30 is disposed axially outward of the first supply port S1 and the second supply port S2.

The first head flow path 31 is disposed between one end of the bridge flow path 30 and the first tank flow path 35 in the axial direction. The first head flow path 31 extends in a direction perpendicular to the axial direction. The first head flow path 31 is connected to the first tank flow path 35 via a first relief valve 45 for releasing excessive high pressure.
The second head flow path 32 is disposed between the first sleeve hole 10 and the second sleeve hole 20. The second head flow path 32 is disposed on an extension line of the first head flow path 31.

The first rod 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 rod flow path 33 extends in a direction intersecting the axial direction. The first rod flow path 33 is connected to the second tank flow path 36 via a second relief valve 46 for releasing excessive high pressure. The first rod flow path 33 is provided with a lock valve 47 (a retention valve for suppressing the arm 105 from lowering due to inertia) for reducing leakage.
The second rod flow passage 34 is disposed between the first sleeve hole 10 and the second sleeve hole 20. The second rod flow passage 34 extends in a direction perpendicular to the axial direction.

The first tank flow path 35 extends outside the first head flow path 31 in a direction perpendicular to the axial direction.
The second tank flow path 36 extends outside the first rod flow path 33 in a direction perpendicular to the axial direction.

Both ends of the bypass flow passage 37 are connected to the second sleeve hole 20. The bypass flow passage 37 is connected to 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 sleeve hole 10 and the second sleeve hole 20. The first casing 51 has a first storage chamber 53 connected to one end of the first sleeve hole 10 and accommodating a first coil spring 52, and a second storage chamber 55 connected to one end of the second sleeve hole 20 and accommodating 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 sleeve hole 10 and the second sleeve hole 20. The second casing 61 has a third accommodating chamber 63 connected to the other end of the first sleeve hole 10 and a fourth accommodating chamber 65 connected to the other end of the second sleeve hole 20. The second casing 61 also has a second pump flow passage 66 extending in a direction perpendicular to the axial direction outside the third accommodating chamber 63 and the fourth accommodating 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 meter-in spool 5 is housed in the first sleeve hole 10 of the valve body 3 so as to be slidable in the axial direction. The meter-in spool 5 is housed so as to be positioned at three positions: a central position Po1 in the axial direction of the first sleeve hole 10, a position Po2 on one axial end side of the first sleeve hole 10 (see FIG. 3), and a position Po3 on the other axial end side of the first sleeve hole 10 (see FIG. 4).
Hereinafter, the central position of the first sleeve hole 10 in the axial direction will be referred to as a first central position Po1. Also, the position on one end side of the first sleeve hole 10 in the axial direction will be referred to as a first supply position Po2, and the position on the other end side of the first sleeve hole 10 in the axial direction will be referred to as a second supply position Po3.
The first sleeve hole 10 and the meter-in spool 5 constitute a meter-in valve 4. The meter-in valve 4 is a four-port three-position change-over valve.

The meter-in spool 5 has, for example, a number of recesses 5a formed in an annular shape, a number of lands 5b formed between the recesses 5a, and a number of notches 5c formed in the lands 5b. The meter-in spool 5 can block the flow path and adjust the flow rate by using the recesses 5a, the lands 5b, the notches 5c, etc. The meter-in spool 5 also has, for example, a first meter-in flow path 11 formed by the recesses 5a, the notches 5c, etc., and a second meter-in flow path 12 formed by the recesses 5a, the notches 5c, etc.

When the meter-in spool 5 is positioned in the first neutral position Po1, the land 5b etc. closes, for example, the first pump port P1, the second pump port P2, the first supply port S1, and the second supply port S2.

3 is an explanatory diagram of an example of the operation of the hydraulic system 109 when the arm 105 of the embodiment is pulled.
As shown in Fig. 3, when the meter-in spool 5 is disposed at the first supply position Po2, the first meter-in passage 11 communicates the first pump port P1 with the first supply port S1. When the meter-in spool 5 is disposed at the first supply position Po2, the second meter-in passage 12 communicates the second pump port P2 with the second supply port S2. As a result, the first pump port P1 and the second pump port P2 communicate with the head port Hp via the first supply port S1 and the second supply port S2, etc., respectively. Note that "communicating" refers to allowing hydraulic oil (i.e., fluid) to flow. For example, "communicating the first pump port P1 with the first supply port S1" means that the first pump port P1 and the first supply port S1 are connected to each other to allow hydraulic oil to flow.

4 is an explanatory diagram of an example of the operation of the hydraulic system 109 when pushing the arm 105 of the embodiment.
4, when the meter-in spool 5 is disposed at the second supply position Po3, it communicates between the first pump port P1 and the first supply port S1 through the first meter-in passage 11. Also, when the meter-in spool 5 is disposed at the second supply position Po3, it communicates between the second pump port P2 and the second supply port S2 through the second meter-in passage 12. As a result, the first pump port P1 and the second pump port P2 communicate with the rod port Rp via the first supply port S1 and the second supply port S2, etc., respectively.

The meter-in spool 5 is a spool for supplying hydraulic oil discharged from the two hydraulic pumps 110 through the pump ports and the like to the hydraulic cylinder 113 from the head port Hp and rod port Rp. In addition, when supplying hydraulic oil to the hydraulic cylinder 113, the meter-in spool 5 controls the amount of hydraulic oil supplied to the hydraulic cylinder 113.

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

The first meter-in solenoid proportional valve 6 and the second meter-in solenoid proportional valve 7 place the meter-in spool 5 in the first neutral position Po1 when both the meter-in solenoid proportional valves 6, 7 are not energized.
The first meter-in solenoid proportional valve 6 is energized while the second meter-in solenoid proportional valve 7 is in a non-energized state, thereby driving the meter-in spool 5 based on an electrical signal to place it in the first supply position Po2 (see FIG. 3). Here, the first meter-in solenoid proportional valve 6 can steplessly control (adjust) the first supply position Po2 according to (in proportion to) the "current value" of the energized electrical signal.

When the second meter-in solenoid proportional valve 7 is energized while the first meter-in solenoid proportional valve 6 is in a non-energized state, it drives the meter-in spool 5 based on an electrical signal to place it in the second supply position Po3 (see FIG. 4). Here, the second meter-in solenoid proportional valve 7 can steplessly control (adjust) the second supply position Po3 according to (proportionally to) the "current value" of the energized electrical signal.

The meter-out spool 15 is housed in the second sleeve hole 20 of the valve body 3 so as to be freely slidable in the axial direction. The meter-out spool 15 is housed so as to be positioned at four positions: a central position Po4 in the axial direction of the second sleeve hole 20, a front position Po5 on one end side of the axial direction of the second sleeve hole 20 (to the right of the central position Po4 in FIG. 3), a position Po6 on one end side of the axial direction of the second sleeve hole 20 (to the right of the central position Po5 in FIG. 3), and a position Po7 on the other end side of the axial direction of the second sleeve hole 20 (see FIG. 4).

Hereinafter, the central position of the second sleeve hole 20 in the axial direction is referred to as a second central position Po4. Also, the position in front of one end side of the second sleeve hole 20 in the axial direction is referred to as a regeneration position Po5. Furthermore, the position on one end side of the second sleeve hole 20 in the axial direction is referred to as a first ejection position Po6, and the position on the other end side of the second sleeve hole 20 in the axial direction is referred to as a second ejection position Po7.
The second sleeve hole 20 and the meter-out spool 15 etc. constitute a meter-out valve 14. Like the meter-in valve 4, the meter-out valve 14 is a four-port three-position change-over valve.

The meter-out spool 15 has, for example, a number of recesses 15a formed in an annular shape, a number of lands 15b formed between the recesses 15a, and a number 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 meter-out flow path 21 (see also FIG. 4) formed by the recesses 15a, etc., and a second meter-out flow path 22 (see also FIG. 3) formed by the recesses 15a, etc.

When the meter-out spool 15 is positioned in the second neutral position Po4, it blocks the first tank port T1, the second tank port T2, the first discharge port D1, and the second discharge port D2, for example, by the land 15b.

3, when the meter-out spool 15 is disposed in a position ranging from the second central position Po4 to the regeneration position Po5, the second tank port T2 and the second discharge port D2 are communicated with each other through the second meter-out passage 22. When the meter-in spool 5 is disposed in the first discharge position Po2, the rod port Rp is communicated with the second rod passage 34 through the rod-side passage 133 and the first rod passage 33. As a result, the rod port Rp is communicated with the bypass passage 37 through the second discharge port D2.
Furthermore, when the meter-out spool 15 is disposed at the regeneration position Po5, the bypass flow path 37 is connected to the second head flow path 32 via the third check valve 43, etc. As a result, the bypass flow path 37 is connected to the head port Hp via the second head flow path 32, the first head flow path 31, the head side flow path 134, etc.

When the meter-out spool 15 is further positioned from the regeneration position Po5 to the first discharge position Po6, the second tank port T2 communicates with the second discharge port D2 via the second meter-out flow path 22. When the meter-in spool 5 is positioned at the first discharge position Po6, the rod port Rp communicates with the second rod flow path 34 via the rod side flow path 133 and the first rod flow path 33. As a result, the rod port Rp communicates with the second tank port T2 via the second discharge port D2.

In this way, by further moving the meter-out spool 15 from the regeneration position Po5 to the first discharge position Po6, the regeneration flow path is blocked and the hydraulic oil is discharged to the tank 120. This allows the arm 105 to move at high speed during regeneration when the meter-out spool 15 is placed at the regeneration position Po5, while during excavation, the meter-out spool 15 can be moved to the first discharge position Po6 to excavate with great force.

As shown in FIG. 4, when the meter-out spool 15 is positioned at the second discharge position Po7, the first tank port T1 and the first discharge port D1 are connected by the first meter-out flow path 21. As a result, the first tank port T1 is connected to the head port Hp via the first discharge port D1, the second head flow path 32, the first head flow path 31, and the head side flow path 134.

The meter-out spool 15 is a spool for discharging the hydraulic oil inside the hydraulic cylinder 113 from the head port Hp and the rod port Rp to a tank 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 to the tank.
The meter-out spool 15 is a spool for supplying hydraulic oil from the inside of the hydraulic cylinder 113 through the rod port Rp to the inside of the hydraulic cylinder 113 through the head port Hp.

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 6 and the second meter-in solenoid proportional valve 7, 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 place the meter-out spool 15 in the second neutral position Po4 when both the meter-out solenoid proportional valves 16, 17 are not 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 electric signal to place it at the regeneration position Po5 (see FIG. 3). Here, the first meter-out solenoid proportional valve 16 can steplessly control (adjust) the regeneration position Po5 according to (proportionally to) the "current value" of the energized electric signal.

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 electric signal to place it in the first discharge position Po6 (see FIG. 3). Here, the first meter-out solenoid proportional valve 16 can steplessly control (adjust) the first discharge position Po6 according to (proportionally to) the "current value" of the energized electric signal.
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, thereby driving the meter-out spool 15 based on an electric signal to place it at the second discharge position Po7 (see FIG. 4). Here, the second meter-out solenoid proportional valve 17 can steplessly control (adjust) the second discharge position Po7 according to (proportionally to) the "current value" of the energized electric signal.

<Function of independent metering valve>
Next, the operation of the independent metering valve 2 will be described.
2, the first meter-in solenoid proportional valve 6 and the second meter-in solenoid proportional valve 7 are de-energized, and the meter-in spool 5 is placed in the first neutral position Po1. The placed meter-in spool 5 closes the first pump port P1, the second pump port P2, the first supply port S1, and the second supply port S2.

In addition, the first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17 are de-energized to place the meter-out spool 15 in the second neutral position Po4. The placed meter-out spool 15 closes the first tank port T1, the second tank port T2, the first drain port D1, and the second drain port D2.
When each of the hydraulic pumps 110A, 110B is driven by a prime mover (not shown), a predetermined flow rate of hydraulic oil is discharged from a discharge port of each of the hydraulic pumps 110A, 110B. For example, the discharged hydraulic oil is returned to a tank via a return circuit (not shown).

3, the meter-out spool 15 is moved in the direction of arrow A1 from the second central position Po4 to the regeneration position Po5. In this case, with the second meter-out solenoid proportional valve 17 in a de-energized state, the first meter-out solenoid proportional valve 16 is switched to an energized state, whereby the meter-out spool 15 is moved toward the first meter-out solenoid proportional valve 16 and is placed at the regeneration position Po5.
By disposing the meter-out spool 15 in the regeneration position Po5, the second rod flow path 34 communicates with the bypass flow path 37 via the second discharge port D2.
Furthermore, when the meter-out spool 15 is disposed at the regeneration position Po5, the bypass flow path 37 communicates with the second head flow path 32, etc. As a result, the bypass flow path 37 communicates with the head port Hp via the second head flow path 32, etc.

Also, the meter-in spool 5 is moved in the direction of the arrow B1 to be placed in the first supply position Po2. In this case, by switching the first meter-in electromagnetic proportional valve 6 to a powered state while the second meter-in electromagnetic proportional valve 7 is in a non-energized state, the meter-in spool 5 is moved toward the second meter-in electromagnetic proportional valve 7 to be placed in the first supply position Po2. By placing the meter-in spool 5 in the first supply position Po2, the first pump port P1 and the first supply port S1 are communicated in the first meter-in flow path 11. Also, by placing the meter-in spool 5 in the first supply position Po2, the second pump port P2 and the second supply port S2 are communicated in the second meter-in flow path 12. As a result, the first pump port P1 is communicated to the head port Hp via the first meter-in flow path 11 and the first supply port S1. Also, the second pump port P2 is communicated to the head port Hp via the second meter-in flow path 12 and the second supply port S2, etc.

Specifically, the first pump port P1 is communicated with the head port Hp via the first meter-in passage 11, the first supply port S1, the first check valve 41 (see FIG. 2), a part of the bridge passage 30, the first head passage 31, and the head side passage 134. In addition, the second pump port P2 is communicated with the head port Hp via the second meter-in passage 12, the second supply port S2, the second check valve 42 (see FIG. 2), a part of the bridge passage 30, the first head passage 31, and the head side passage 134.
On the other hand, by disposing the meter-in spool 5 at the first supply position Po2, the rod port Rp is communicated with the second rod flow passage 34, etc. As a result, the rod port Rp is communicated with the bypass flow passage 37 via the second discharge port D2. Therefore, a regeneration passage is formed that passes the rod port Rp through the head port Hp.

In this state, the hydraulic oil discharged from the first pump 110A is supplied as indicated by the arrows to the first pump port P1, the first meter-in flow path 11, the first supply port S1, the first check valve 41, and a part of the bridge flow path 30. Also, the hydraulic oil discharged from the second pump 110B flows as indicated by the arrows into the second pump port P2, the second meter-in flow path 12, the second supply port S2, the second check valve 42, and a part of the bridge flow path 30.
The hydraulic oil discharged from the first pump 110A and the hydraulic oil discharged from the second pump 110B are joined in a part of the bridge flow passage 30 and supplied to the head port Hp as shown by the arrow via the first head flow passage 31 and the head side flow passage 134.

Furthermore, hydraulic oil on the piston rod 115 side of the cylinder 114 is guided as indicated by the arrows to the bypass flow path 37 via the rod port Rp, the rod-side flow path 133, the lock valve 47, the first rod flow path 33, the second rod flow path 34, and the second drain port D2. The hydraulic oil guided to the bypass flow path 37 is guided as indicated by the arrows to the third check valve 43 (see FIG. 2), the first drain port D1, and the second head flow path 32. The hydraulic oil guided to the second head flow path 32 flows into the cylinder head side of the cylinder 114 as indicated by the arrows via the first head flow path 31, the head-side flow path 134, and the head port Hp.
That is, the entire amount (i.e., 100%) of the hydraulic oil flowing out from the rod port Rp passes through a regeneration passage and flows into the cylinder head side of the cylinder 114 from the head port Hp, where it is regenerated.

In this way, by moving the meter-in spool 5 to the first supply position Po2 and the meter-out spool 15 to the regeneration position Po5, the hydraulic oil discharged from the two pumps 110A, 110B is joined together and supplied to the cylinder head side of the hydraulic cylinder 113.
On the other hand, hydraulic oil on the piston rod 115 side of the cylinder 114 flows from the rod port Rp through the head port Hp to the cylinder head side of the cylinder 114. As a result, the piston rod 115 of the hydraulic cylinder 113 is pushed out as shown by the arrow E1 so as to protrude from the cylinder 114.

As a result, the arm 105 of the construction machine 100 is pulled (or lowered) until it reaches the excavation position. In this state, the cylinder pressure on the cylinder head side of the cylinder 114 rises above the threshold value. Here, the cylinder pressure is detected as the detected pressure by the pressure sensor 26. Therefore, when the detected pressure rises above the threshold value, the control unit 25 switches the first meter-out solenoid proportional valve 16 to an energized state, thereby moving the meter-out spool 15 in the direction of arrow A1 to the first discharge position Po6. The effect of placing the meter-out spool 15 in the first discharge position Po6 will be explained in detail later.

That is, the regeneration passage connects the rod port Rp to the head port Hp when the cylinder pressure on the cylinder head side is below a threshold value. As a result, the entire amount (i.e., 100%) of the hydraulic oil flowing out from the rod port Rp is guided to the head port Hp by the regeneration passage, and flows into the cylinder head side of the cylinder 114. This allows the arm 105 to move at high speed during regeneration with the meter-out spool 15 positioned at the regeneration position Po5.

In the embodiment, an example is described in which the rod port Rp is connected only to the head port Hp, and all (100%) of the hydraulic oil flowing out of the rod port Rp flows from the head port Hp to the cylinder head side through the regeneration passage, but this is not limited to the above. As another example, the rod port Rp may be connected to both the head port Hp and the tank 120. In this case, the hydraulic oil flowing out of the rod port Rp flows in two, into the head port Hp and the tank 120. In other words, a portion of the hydraulic oil flowing out of the rod port Rp flows from the head port Hp to the cylinder head side through the regeneration passage.

Next, the meter-out spool 15 at the regeneration position Po5 is placed at the first discharge position Po6, thereby connecting the second tank port T2 and the second discharge port D2 through the second meter-out flow path 22. As a result, the rod port Rp is connected to the second tank port T2 via the second meter-out flow path 22 and the second discharge port D2. Meanwhile, the first discharge port D1 is blocked by the meter-out spool 15.

In this state, the hydraulic oil on the piston rod 115 side of the cylinder 114 is discharged (returned) to the tank 120 via the rod port Rp, the rod side flow path 133, the lock valve 47, the first rod flow path 33, the second rod flow path 34, the second discharge port D2, the second meter-out flow path 22, and the second tank port T2.

On the other hand, the hydraulic oil discharged from the first pump 110A and the hydraulic oil discharged from the second pump 110B continue to merge in a part of the bridge flow passage 30 and are supplied to the head port Hp as shown by the arrow through the first head flow passage 31 and the head side flow passage 134. As a result, the piston rod 115 of the hydraulic cylinder 113 continues to be pushed out as shown by the arrow E1 so as to protrude from the cylinder 114.
In this state, the construction machine 100 (see FIG. 1) continues to pull the arm 105 to start excavation. As a result, when the construction machine 100 is excavating, the excavation force can be efficiently secured by returning the hydraulic oil from the rod port Rp to the tank 120 as in the normal flow of hydraulic oil. That is, when excavating, it is possible to excavate with a large force by moving the meter-out spool 15 to the first discharge position Po6.

As shown in FIG. 4, the meter-out spool 15 is moved in the direction of the arrow A2 to the second discharge position Po7. In this case, the first meter-out solenoid proportional valve 16 is switched to a non-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 toward the first meter-out solenoid proportional valve 16 and is placed at the second discharge position Po7. By placing the meter-out spool 15 at the second discharge position Po7, the first tank port T1 and the first discharge port D1 are connected by the first meter-out flow path 21. As a result, the first tank port T1 is passed through the head port Hp via the first meter-out flow path 21, the first discharge port D1, the second head flow path 32, the first head flow path 31, and the head side flow path 134. Meanwhile, the second tank port T2 is blocked by the meter-out spool 15.

The meter-in spool 5 is also moved in the direction of arrow B2 to be placed in the second supply position Po3. In this case, the first meter-in solenoid proportional valve 6 is switched to a non-energized state, and the second meter-in solenoid proportional valve 7 is switched to an energized state, thereby moving the meter-in spool 5 toward the first meter-in solenoid proportional valve 6 and placing it in the second supply position Po3. By placing the meter-in spool 5 in the second supply position Po3, the first pump port P1 and the first supply port S1 are connected by the first meter-in flow path 11. This allows the first pump port P1 to be connected to the rod port Rp via the first meter-in flow path 11 and the first supply port S1, etc.

In addition, by placing the meter-in spool 5 at the second supply position Po3, the second pump port P2 and the second supply port S2 are connected through the second meter-in passage 12. This allows the rod port Rp to communicate with the second pump port P2 via the second meter-in passage 12 and the second supply port S2, etc.

Specifically, the rod port Rp is connected to the first pump port P1 via the first meter-in passage 11, the first supply port S1, the first check valve 41 (see FIG. 2), a part of the bridge passage 30, the first rod passage 33, and the rod side passage 133. In addition, the rod port Rp is connected to the second pump port P2 via the second meter-in passage 12, the second supply port S2, the second check valve 42 (see FIG. 2), a part of the bridge passage 30, the first rod passage 33, and the rod side passage 133.

In this state, the hydraulic oil discharged from the first pump 110A is supplied as indicated by the arrows to the first pump port P1, the first meter-in flow path 11, the first supply port S1, the first check valve 41, and a part of the bridge flow path 30. Also, the hydraulic oil discharged from the second pump 110B flows into the second pump port P2, the second meter-in flow path 12, the second supply port S2, the second check valve 42, and a part of the bridge flow path 30 as indicated by the arrows.
The hydraulic oil discharged from the first pump 110A and the hydraulic oil discharged from the second pump 110B are joined in a part of the bridge flow passage 30 and supplied to the rod port Rp via the first rod flow passage 33 and the rod side flow passage 133 as shown by the arrow.

In addition, the hydraulic oil on the cylinder head side of the cylinder 114 is discharged (returned) to the tank 120 as shown by the arrow via the head port Hp, the head side flow path 134, the first head flow path 31, the second head flow path 32, the first discharge port D1, the first meter-out flow path 21, and the first tank port T1.
As a result, the piston rod 115 of the hydraulic cylinder 113 is retracted as indicated by arrow E1 so as to be pushed into the cylinder 114. This causes the arm 105 of the construction machine 100 to be pushed in a direction away from the excavation position (or to rise upward).

In this way, the independent metering valve 2 is equipped with a meter-in spool 5 and a meter-out spool 15. By controlling the drive of the meter-in spool 5 and the meter-out spool 15, the piston rod 115 can be moved in two directions, the directions of the arrows E1 and E2. In this way, the spool that switches the movement of the piston rod 115 in the two directions can be divided into the meter-in spool 5 and the meter-out spool 15.

In addition, the meter-in spool 5 is driven and controlled to the first supply position Po2 by the first meter-in electromagnetic proportional valve 6. The meter-out spool 15 is driven and controlled to the regeneration position Po5 and the first discharge position Po6 by the second meter-out electromagnetic proportional valve 17. This allows the piston rod 115 of the hydraulic cylinder 113 to move in the direction of the arrow E1 (one direction).
Furthermore, the second meter-in solenoid proportional valve 7 drives and controls the meter-in spool 5 to the second supply position Po3. The first meter-out solenoid proportional valve 16 drives and controls the meter-out spool 15 to the second discharge position Po7. This allows the piston rod 115 of the hydraulic cylinder 113 to move in the direction of the arrow E2 (the other direction).

Therefore, the drive control of the meter-in spool 5 and the meter-out spool 15 can be electrically and individually adjusted by the first meter-in solenoid proportional valve 6, the second meter-in solenoid proportional valve 7, the first meter-out solenoid proportional valve 16, and the second meter-out solenoid proportional valve 17. In other words, the meter-in spool 5 and the meter-out spool 15 can form an independent metering valve 2. As a result, when adjusting the independent metering valve 2 (i.e., the hydraulic control device 1) to suit the application of, for example, construction machinery, the drive control of the meter-in spool 5 and the meter-out spool 15 can be individually adjusted. This makes it easier to adjust the actual machine and shortens the adjustment period.

Here, the first meter-in solenoid proportional valve 6 can adjust the first supply position steplessly in proportion to the "current value" of the electric signal applied. The second meter-in solenoid proportional valve 7 can adjust the second supply position steplessly in proportion to the "current value" of the electric signal applied. Furthermore, the first meter-out solenoid proportional valve 16 can adjust the first discharge position steplessly in proportion to the "current value" of the electric signal applied. The second meter-out solenoid proportional valve 17 can adjust the second discharge position steplessly in proportion to the "current value" of the electric signal applied.
Therefore, when adjusting the independent metering valve 2 (hydraulic control device 1) in accordance with the application of a construction machine or the like, the drive control of the meter-in spool 5 and the meter-out spool 15 can be adjusted steplessly. This makes it easier to adjust the actual machine, and shortens the adjustment period.

The meter-in spool 5 and meter-out spool 15 are driven and controlled by the first meter-in solenoid proportional valve 6, the second meter-in solenoid proportional valve 7, the first meter-out solenoid proportional valve 16, and the second meter-out solenoid proportional valve 17. This makes it possible to electrically adjust the drive control of the meter-in spool 5 and meter-out spool 15, making it possible to respond to markets where electrification is expected in the future and increasing versatility.

In this way, the hydraulic control device 1 is configured to have one meter-in spool 5 and one meter-out spool 15, so that the piston rod 115 of the hydraulic cylinder 113 can be switched in two directions. Therefore, one meter-in spool 5 and one meter-out spool 15 can be used to switch the piston rod 115 in two directions. Therefore, it is not necessary to have, for example, two meter-in spools and two meter-out spools to switch the piston rod 115 in two directions. This simplifies the circuit configuration of the independent metering valve 2 (i.e., the meter-in spool and the meter-out spool).

As shown in FIG. 1, the construction machine 100 has a hydraulic control device 1 equipped with an independent metering valve 2 mounted on a rotating body 101. With this configuration, when adjusting the hydraulic control device 1 to suit the application of the construction machine 100, the drive control of the meter-in spool 5 and the meter-out spool 15 can be adjusted individually, shortening the adjustment period.

As described above, according to the construction machine 100 of this embodiment, when hydraulic oil is supplied to the cylinder head side of the cylinder 114, the meter-out spool 15 is placed in the regeneration position Po5, so that the rod port Rp of the cylinder 114 can be connected to the head port Hp through the regeneration passage. Therefore, hydraulic oil on the rod end side of the cylinder 114 can be flowed to the head end side to be regenerated. In this way, by using hydraulic oil on the rod end side for regeneration, the piston rod 115 can be protruded from the cylinder 114 quickly (swiftly) with little energy, as shown by the arrow E1. Therefore, the workability of the hydraulic cylinder 113 (i.e., the arm 105) can be improved and energy can be saved.

Also, with the meter-out spool 15 positioned at the regeneration position Po5, the rod port Rp may be connected to both the head port Hp and the tank 120. In this case, the hydraulic oil flowing out of the rod port Rp is divided into two and flows into the head port Hp and the tank 120 (i.e., the second discharge flow passage 136). That is, a portion of the hydraulic oil flowing out of the rod port Rp can be regenerated by flowing from the head port Hp to the cylinder head side through the regeneration passage.

Therefore, the piston rod 115 can be protruded from the cylinder 114 quickly with little energy as indicated by the arrow E1, thereby improving the operability of the hydraulic cylinder 113 (i.e., the arm 105) and achieving energy saving.
Furthermore, by connecting to both the head port Hp and the tank 120, it is possible to adjust the flow rate of the hydraulic oil flowing from the rod end side to the head end side of the cylinder 114. Therefore, for example, depending on the application of the cylinder 114, the flow rate of the hydraulic oil can be adjusted with a simple configuration, and energy savings can be achieved.

For example, when performing work such as excavation with the construction machine 100, the meter-out spool 15 is placed in the first discharge position Po6. In this state, the rod port Rp is connected only to the tank 120. Therefore, the hydraulic oil on the piston rod 115 side of the cylinder 114 is returned to the tank 120 from the rod port Rp via the second tank port T2. Therefore, the piston rod 115 can be protruded from the cylinder 114 as shown by the arrow E1 using only the hydraulic oil fluid discharged from the two pumps 110A, 110B. Therefore, work such as excavation can be performed while efficiently securing the excavation force of the cylinder 114 (i.e., the arm 105).

Furthermore, the independent metering valve 2 is provided with a pressure sensor 26 that detects, for example, the cylinder pressure on the head end side of the cylinder 114. Therefore, the meter-out spool 15 can be driven and controlled by the control unit 25 based on the pressure detected by the pressure sensor 26.
That is, when the cylinder pressure is less than the threshold value, the meter-out spool 15 is controlled by the control unit 25 to connect the rod port Rp to the head port Hp. Therefore, the entire amount (i.e., 100%) of the hydraulic oil flowing out from the rod port Rp is guided to the head port Hp through the regeneration passage, and is allowed to flow into the cylinder head side of the cylinder 114 for regeneration.

On the other hand, when the cylinder pressure rises to or above the threshold value, the meter-out spool 15 is controlled by the control unit 25 to connect the rod port Rp to the tank port T2.
In this manner, by controlling the drive of the meter-out spool 15 based on the pressure detected by the pressure sensor, it is possible to improve the operability of the hydraulic cylinder 113 with a simple structure and achieve energy savings.

In addition, the meter-out spool 15 is configured to block the flow path and adjust the flow rate, for example, by using the recess 15a, land 15b, and notch 15c. Therefore, by utilizing the recess 15a, land 15b, and notch 15c, a regeneration passage that allows hydraulic oil flowing out of the rod port Rp to flow into the head port Hp can be formed with a simple configuration.

In addition, the first meter-out solenoid proportional valve 16 and the second meter-out solenoid proportional valve 17 are employed in the drive section that drives the meter-out spool 15. Therefore, a regeneration passage that allows the hydraulic oil flowing out of the rod port Rp to flow into the head port Hp can be formed with a simple configuration.
Furthermore, the first meter-in solenoid proportional valve 6, the second meter-in solenoid proportional valve 7, the first meter-out solenoid proportional valve 16, and the second meter-out solenoid proportional valve 17 can be driven and controlled by the control unit 25 based on the detection signal of the pressure sensor 26. Therefore, a regeneration passage that allows the hydraulic oil flowing out from the rod port Rp to flow into the head port Hp can be formed with a simple configuration.

In addition, a hydraulic system 109 is installed on the construction machine 100, and the cylinder 114 is used to drive the arm 105. Therefore, before performing work such as excavation with the arm 105, the hydraulic oil flowing out from the rod port Rp can be regenerated by flowing into the head port Hp. This allows the piston rod 115 to be protruded from the cylinder 114 quickly and with little energy.

On the other hand, when performing work such as excavation with the arm 105, the piston rod 115 can be protruded from the cylinder 114 only with the hydraulic fluid discharged from the two pumps 110A, 110B. Therefore, work such as excavation can be performed while efficiently securing the excavation force of the cylinder 114 (i.e., the arm 105).
In this way, before performing work such as excavation with the arm 105, the hydraulic oil flowing out from the rod port Rp is caused to flow into the head port Hp and regenerated. This makes it possible to improve the workability of the hydraulic cylinder 113 (i.e., the arm 105 of the construction machine 100) and to achieve energy savings.

The control method of this embodiment includes a step of connecting to the tank 120 when the pressure detected by the pressure sensor 26 is equal to or greater than a threshold value, and a step of connecting to the head port Hp when the pressure detected by the pressure sensor 26 is less than the threshold value.
In the process of connecting to the tank 120, when the pressure detected by the pressure sensor 26 is equal to or higher than the threshold value, the rod port Rp is connected to the tank 120. Therefore, similar to a normal cylinder, the piston rod 115 can be protruded from the cylinder 114 only with the hydraulic oil discharged from the two pumps 110A, 110B. This allows the cylinder 114 (i.e., the arm 105 of the construction machine 100) to perform work such as excavation.

Meanwhile, in the process of connecting to the head port Hp, when the pressure detected by the pressure sensor 26 is below the threshold value, the rod port Rp is connected to the head port Hp, so that the hydraulic oil on the rod end side of the cylinder 114 can be regenerated by flowing into the head end side. Therefore, by using the hydraulic oil on the rod end side, the piston rod 115 can be protruded from the cylinder 114 quickly with little energy. This improves the workability of the hydraulic cylinder 113 (i.e., the arm 105 of the construction machine 100) and also saves energy.

In the process of connecting to the head port Hp described above, the rod port Rp may be connected to both the head port Hp and the tank 120. This allows the flow rate of hydraulic oil flowing from the rod end side to the head end side of the cylinder 114 to be adjusted. Therefore, for example, depending on the application of the cylinder 114, the flow rate of the hydraulic oil can be adjusted with a simple configuration, and energy savings can be achieved.

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 embodiment, the hydraulic cylinder 113 is used as an actuator, but this is not limiting. For example, the present invention may be applied to an actuator such as a hydraulic motor.

In the above embodiment, the solenoid proportional valves 6, 7, 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 6, 7, 16, and 17, the meter-in spool 5 and the meter-out spool 15 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. In addition, the above-described variations may be combined.

2...Independent metering valve (fluid valve in the claims), 3...Valve body, 10...First sleeve hole (sleeve hole), 15...Meter-out spool, 15b...Land, 15c...Notch, 16...First meter-out solenoid proportional valve (solenoid valve), 17...Second meter-out solenoid proportional valve (solenoid valve), 20...Second sleeve hole (sleeve hole), 25...Control unit, 26...Pressure sensor, 100...Construction machine, 105...Arm, 106...Bucket, 109...Hydraulic system (fluid system), 113...Hydraulic cylinder (actuator), D1...First discharge port (supply/discharge port), D2...Second discharge port (supply/discharge port), Hp...Head port (cylinder port), Rp...Rod port (discharge port), T1...First tank port (tank port), T2...Second tank port (tank port), 135...First discharge flow path (tank passage), 136...Second discharge flow path (tank passage)

Claims (8)

a valve body having a supply/discharge port connected to one of a discharge port or a cylinder port provided in an actuator driven by a fluid, and a tank port connected to a tank passage;
a meter-out spool that is movably provided in a sleeve hole formed in the valve body and controls the amount of the fluid discharged from the actuator,
The meter-out spool is a fluid valve that, by movement of the meter-out spool, brings only the cylinder port into communication with the discharge port, or brings both the cylinder port and the tank passage into communication with the discharge port. The fluid valve according to claim 1, wherein the meter-out spool adjusts the flow rate of the fluid flowing from the discharge port to only the cylinder port, or adjusts the flow rate of the fluid flowing from the discharge port to both the cylinder port and the tank passage, by moving the meter-out spool. The fluid valve according to claim 1 or 2, wherein the meter-out spool has a notch that blocks the flow path of the cylinder port or the tank passage, or adjusts the flow rate of the fluid flowing through the flow path. The fluid valve according to any one of claims 1 to 3, wherein the meter-out spool has a land that blocks the flow path of the cylinder port or the tank passage, or adjusts the flow rate of the fluid flowing through the flow path. A fluid valve;
an actuator driven by a fluid whose flow rate is adjusted by the fluid valve;
The fluid valve includes:
a valve body having a supply/discharge port connected to one of a discharge port or a cylinder port provided in the actuator driven by a fluid, and a tank port connected to a tank passage;
a meter-out spool that is movably provided in a sleeve hole formed in the valve body and controls the amount of the fluid discharged from the actuator,
the meter-out spool brings only the cylinder port into communication with the discharge port, or brings both the cylinder port and the tank passage into communication with the discharge port, by movement of the meter-out spool;
The actuator includes a cylinder and a piston rod slidably provided within the cylinder,
a pressure sensor for detecting either the pressure in the cylinder or the discharge pressure of a pump that supplies the fluid to the cylinder port;
When the pressure detected by the pressure sensor is equal to or higher than a threshold value, the meter-out spool is driven and controlled to connect the discharge port to the tank passage,
When the detected pressure is less than a threshold value, the meter-out spool is driven and controlled to connect the discharge port to the cylinder port. The fluid system according to claim 5 , further comprising a solenoid valve that drives the meter-out spool based on an electrical signal. The fluid system according to claim 6, further comprising a control unit that controls the operation of the solenoid valve based on a detection signal from the pressure sensor. A fluid valve;
an arm driving actuator that is driven by the fluid whose flow rate is adjusted by the fluid valve and drives the arm;
Equipped with
The fluid valve includes:
a valve body having a supply/discharge port connected to one of a discharge port or a cylinder port provided in the actuator driven by a fluid, and a tank port connected to a tank passage;
a meter-out spool that is movably provided in a sleeve hole formed in the valve body and controls the amount of the fluid discharged from the actuator,
the meter-out spool brings only the cylinder port into communication with the discharge port, or brings both the cylinder port and the tank passage into communication with the discharge port, by movement of the meter-out spool;
The actuator includes a cylinder and a piston rod slidably provided within the cylinder,
a pressure sensor for detecting either the pressure in the cylinder or the discharge pressure of a pump that supplies the fluid to the cylinder port;
When the pressure detected by the pressure sensor is equal to or higher than a threshold value, the meter-out spool is driven and controlled to connect the discharge port to the tank passage,
When the detected pressure is less than a threshold value, the meter-out spool is driven and controlled to connect the discharge port to the cylinder port.

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