JP7805484B2 - Fluid Pressure Control Device - Google Patents

Description

The present invention relates to a fluid pressure control device.

JP2019-94973A discloses a construction machine such as a hydraulic excavator equipped with a variable displacement hydraulic pump that discharges hydraulic oil, a hydraulic actuator, and a control valve that controls the amount and direction of hydraulic oil supplied from the hydraulic pump to the hydraulic actuator. The control valve has a housing, a spool movably accommodated in the housing, and a pair of springs that bias the spool to its initial position. The housing is formed with a pair of actuator ports connected to the hydraulic actuator by a pair of actuator oil passages, and a pair of pilot ports through which hydraulic oil (pilot oil) is introduced to move the spool. The construction machine is equipped with a pressure reducing valve that reduces the pressure of the hydraulic oil discharged from the hydraulic pump to generate primary pressure, and an electromagnetic proportional pressure reducing valve that is introduced with the primary pressure and controls the pressure (secondary pressure) acting on the pilot port; the spool is moved when pilot oil is supplied to the pilot port.

In construction machinery such as that described in JP2019-94973A, the hydraulic pump's discharge pressure is reduced by a pressure reducing valve to generate primary pressure, and the pilot oil at primary pressure is directed to an electromagnetic proportional pressure reducing valve to generate secondary pressure, and the pilot oil at secondary pressure is directed to the pilot chamber. However, if the pressure reducing valve is installed inside the control valve housing, the oil path becomes complicated and the housing becomes larger.

Furthermore, in construction machinery such as that described in JP2019-94973A, the pilot pump discharge pressure may be directly directed to the electromagnetic proportional pressure reducing valve as the primary pressure, depending on the user's needs. However, if the pressure reducing valve is installed inside the control valve housing, it is difficult to create an oil path that directs only the pilot pump discharge pressure to the electromagnetic proportional pressure reducing valve, making it difficult to directly direct the pilot pump discharge pressure to the electromagnetic proportional pressure reducing valve.

The present invention aims to prevent the housing from becoming too large in a fluid pressure control device and, if necessary, enable the discharge pressure of the pilot pump to be directed to the solenoid valve as primary pressure.

According to one aspect of the present invention, there is provided a fluid pressure control device for controlling an actuator driven by hydraulic fluid discharged from a pump, the fluid pressure control device comprising: a control valve for controlling the flow of hydraulic fluid supplied to or discharged from the actuator; a solenoid valve for generating pilot pressure for controlling the control valve; a main valve block in which the control valve and the solenoid valve are provided; and a sub-valve block detachably provided in the main valve block. The main valve block includes a supply passage for supplying the hydraulic fluid discharged from the pump; and a sub-valve block that branches off from the supply passage upstream of the control valve and is capable of directing a portion of the fluid discharged from the pump to the sub-valve block as pilot fluid. A first inlet passage, a first primary pressure passage that introduces primary pilot pressure from the sub-valve block or the pilot pump to the solenoid valve, and a first drain passage that can discharge drain fluid from the sub-valve block to a tank are formed, and the first inlet passage, the first primary pressure passage, and the first drain passage are formed to open on the outer surface of the main valve block, and the sub-valve block has openings formed on its outer surface that can communicate with the first inlet passage, the first primary pressure passage, and the first drain passage, respectively, and is provided with a primary pressure generating valve that can reduce the pressure of the pilot fluid introduced through the first inlet passage to generate primary pilot pressure and introduce it to the first primary pressure passage.

FIG. 1 is a fluid pressure circuit diagram of a fluid pressure control device according to an embodiment of the present invention, showing a state in which a sub-valve block is attached to a main valve block. FIG. 2 is a side view showing the mounting surface of the sub-valve block in the main valve block. FIG. 3 is a cross-sectional view of the sub-valve block, showing the spool seated on the first plug. FIG. 4 is a cross-sectional view showing the sub-valve block, illustrating a state in which the spool is separated from the first plug. FIG. 5 is a cross-sectional view of the sub-valve block, showing the spool moved further to the right from the position shown in FIG. FIG. 6 is a fluid pressure circuit diagram of a fluid pressure control device according to an embodiment of the present invention, showing a state in which a pilot pump is connected to a main valve block. FIG. 7 is a cross-sectional view showing a sub-valve block according to a modified embodiment of the present invention, and corresponds to FIG.

With reference to the drawings, a fluid pressure control device 100 relating to an embodiment of the present invention will be described.

The fluid pressure control device 100 is a device that controls actuators driven by hydraulic fluid discharged from a pump, and is mounted on work machines such as construction machinery, agricultural machinery, and industrial machinery. Below, we will explain the case where the fluid pressure control device 100 is mounted on a hydraulic excavator and used to control the operation of actuators such as hydraulic motors for traveling and hydraulic cylinders for driving booms, arms, buckets, etc. While we will explain an example in which hydraulic oil is used as the hydraulic fluid to drive the actuators of a hydraulic excavator, other fluids such as hydraulic water may also be used as the working fluid.

First, referring to the fluid pressure circuit diagram in Figure 1, we will explain the overall configuration of the fluid pressure control device 100.

The fluid pressure control device 100 comprises a variable displacement hydraulic pump 5 as a pump, a hydraulic cylinder 6 as an actuator driven by hydraulic fluid discharged from the hydraulic pump 5, a supply passage 20 that supplies the hydraulic fluid discharged from the hydraulic pump 5, a control valve 10 provided in the supply passage 20 to control the flow of hydraulic fluid supplied to and discharged from the hydraulic cylinder 6, a pair of actuator passages 21 connected to the control valve 10 and the hydraulic cylinder 6 and through which hydraulic fluid supplied to and discharged from the hydraulic cylinder 6 flows, and a discharge passage 22 connected to the control valve 10 and a tank 4 that directs hydraulic fluid discharged from the hydraulic cylinder 6 to the tank 4. Multiple hydraulic cylinders 6 and control valves 10 are provided, and Figure 1 shows one hydraulic cylinder 6 and two control valves 10a and 10b as representatives.

The hydraulic pump 5 is driven by an engine mounted on the hydraulic excavator. However, the hydraulic pump 5 may also be driven by an electric motor. The hydraulic cylinder 6 comprises a cylinder tube 6a, a piston rod 6b inserted into the cylinder tube 6a, and a piston 6c attached to the end of the piston rod 6b and sliding along the inner surface of the cylinder tube 6a. The interior of the cylinder tube 6a is divided by the piston 6c into a rod-side chamber 6d and a bottom-side chamber 6e. Hydraulic oil is supplied to and discharged from the rod-side chamber 6d and the bottom-side chamber 6e through an actuator passage 21.

The supply passage 20 is connected to the hydraulic pump 5 and the control valve 10, and guides the hydraulic oil discharged from the hydraulic pump 5 to the control valve 10. Of the pair of actuator passages 21, one actuator passage 21a is connected to the control valve 10 and the rod side chamber 6d of the hydraulic cylinder 6, and the other actuator passage 21b is connected to the control valve 10 and the bottom side chamber 6e of the hydraulic cylinder 6. Depending on the position of the control valve 10, one of the pair of actuator passages 21 is connected to the supply passage 20 and the other is connected to the discharge passage 22.

The control valve 10 is a 4-port, 3-position spool valve, and in this embodiment, multiple control valves 10 with a similar configuration are provided corresponding to each hydraulic cylinder 6. The control valve 10 switches its position by directing secondary pilot pressure to a pair of pilot pressure chambers 11 through a pilot passage 16 (described below) depending on the direction and amount of operation of the operating lever 9 by the operator. The control valve 10 switches its position among a neutral position 10A, an extension position 10B, and a retraction position 10C depending on the magnitude of the secondary pilot pressure supplied to the pair of pilot pressure chambers 11. Details of the control of the control valve 10 will be described later.

The fluid pressure control device 100 also includes a pilot passage 16 branching off from the supply passage 20 and directing pilot pressure for controlling the control valve 10 to a pair of pilot pressure chambers 11, a primary pressure generating valve 30 provided in the pilot passage 16 and generating primary pilot pressure, a drain passage 17 directing drain oil from the primary pressure generating valve 30 to the tank 4, an electromagnetic proportional pressure reducing valve 7 provided in the pilot passage 16 and serving as an electromagnetic valve for generating secondary pilot pressure for controlling the control valve 10 from the primary pilot pressure, and a controller 8 controlling the operation of the electromagnetic proportional pressure reducing valve 7.

The pilot passage 16 branches off from the supply passage 20 upstream of the control valve 10 and is connected to a pair of pilot pressure chambers 11 of the control valve 10. A portion of the hydraulic oil discharged from the hydraulic pump 5 is guided to the pilot passage 16 as pilot oil. A primary pressure generating valve 30 is provided upstream of the pilot passage 16, and the pilot passage 16 branches off into two branch passages 16a, 16b downstream of the primary pressure generating valve 30, which are connected to a pair of pilot pressure chambers 11a, 11b, respectively. An electromagnetic proportional pressure reducing valve 7 is provided in each of the two branch passages 16a, 16b.

The primary pressure generating valve 30 reduces the pressure of the pilot oil guided from the hydraulic pump 5 to the pilot passage 16, generating primary pilot pressure that is guided to the electromagnetic proportional pressure reducing valve 7. The primary pressure generating valve 30 operates to maintain a constant primary pilot pressure regardless of the pressure of the pilot oil guided from the hydraulic pump 5 to the supply passage 20. The detailed configuration of the primary pressure generating valve 30 will be described later.

The electromagnetic proportional pressure reducing valve 7 is electrically connected to the controller 8 and generates a secondary pilot pressure in response to a signal from the controller 8. In the pilot passage 16, a primary pilot pressure is generated by the primary pressure generating valve 30 and directed to each of the two electromagnetic proportional pressure reducing valves 7, which then generate secondary pilot pressures that are directed to the pair of pilot pressure chambers 11, respectively. This controls the control valve 10. Furthermore, oil is discharged from the electromagnetic proportional pressure reducing valve 7 through passage 18. Passage 18 is connected to the drain passage 17, and oil discharged from the electromagnetic proportional pressure reducing valve 7 is discharged to the tank 4 through passage 18 and the drain passage 17.

The controller 8 is composed of a microcomputer that includes a CPU (Central Processing Unit) that performs calculations, a ROM (Read-Only Memory) that stores control programs executed by the CPU, and a RAM (Random Access Memory) that stores the results of CPU calculations. The controller 8 may be composed of a single microcomputer or multiple microcomputers.

The controller 8 controls the electromagnetic proportional pressure reducing valve 7 by transmitting a control signal corresponding to the direction and amount of operation of the operating lever 9. When the operating lever 9 is not operated, the controller 8 controls the electromagnetic proportional pressure reducing valve 7 so that secondary pilot pressure is not introduced into the pair of pilot pressure chambers 11. As a result, the control valve 10a is held in the neutral position 10A by the pair of springs 14. When the control valve 10a is in the neutral position 10A, the pair of actuator passages 21 are not connected to either the supply passage 20 or the discharge passage 22. When the operating lever 9 is operated to switch the control valve 10 to the extension position 10B, the controller 8 controls the electromagnetic proportional pressure reducing valve 7 so that secondary pilot pressure is introduced into the pilot pressure chamber 11a. As a result, the control valve 10a is switched to the extension position 10B against the biasing force of the spring 14. When the control valve 10a is in the extension position 10B, the actuator passage 21b communicates with the supply passage 20, so that hydraulic oil is guided from the hydraulic pump 5 to the bottom side chamber 6e, and the actuator passage 21a communicates with the discharge passage 22, so that hydraulic oil in the rod side chamber 6d is discharged to the tank 4, and the hydraulic cylinder 6 extends.

Furthermore, when the operating lever 9 is operated to switch the control valve 10 to the retraction position 10C, the controller 8 controls the electromagnetic proportional pressure reducing valve 7 so that secondary pilot pressure is directed to the pilot pressure chamber 11b. As a result, the control valve 10a is switched to the retraction position 10C against the biasing force of the spring 14. When the control valve 10a is in the retraction position 10C, the actuator passage 21b communicates with the discharge passage 22, so that the hydraulic oil in the bottom side chamber 6e is discharged to the tank 4, and the actuator passage 21a communicates with the supply passage 20, so that the hydraulic oil is directed from the hydraulic pump 5 to the rod side chamber 6d, causing the hydraulic cylinder 6 to retract. In this manner, the control valve 10a is controlled.

Next, we will explain in detail the main valve block 1 and sub-valve block 2, which form the aforementioned hydraulic circuit.

The fluid pressure control device 100 comprises a main valve block 1 and a sub-valve block 2 that is detachably mounted to the main valve block 1. Figure 1 shows the areas formed in the main valve block 1 and the areas formed in the sub-valve block 2 in the fluid pressure circuit. As shown in Figure 1, the pilot passage 16 is formed across the main valve block 1 and the sub-valve block 2, and the primary pressure generating valve 30 is provided in the sub-valve block 2. In this way, in the fluid pressure control device 100, the primary pressure generating valve 30 is provided not in the main valve block 1 but in a sub-block that is detachable from the main valve block 1. This prevents the oil paths in the main valve block 1 from becoming complicated. This is explained in detail below.

The main valve block 1 is provided with a control valve 10 and an electromagnetic proportional pressure reducing valve 7, and is formed with a supply passage 20, an actuator passage 21, and a discharge passage 22. The main valve block 1 also forms a pilot passage 16 and a portion of a drain passage 17. Specifically, the main valve block 1 is formed with a first inlet passage 25, which is the most upstream of the pilot passage 16; a first primary pressure passage 26, which is part of the pilot passage 16 and directs primary pilot pressure generated by the primary pressure generating valve 30 to the electromagnetic proportional pressure reducing valve 7; a first drain passage 27, which is part of the drain passage 17 and discharges drain oil from the primary pressure generating valve 30 to the tank 4; and branch passages 16a and 16b of the pilot passage 16. The first inlet passage 25 branches off from the supply passage 20 upstream of the control valve 10 and directs a portion of the hydraulic oil discharged from the hydraulic pump 5 to the sub-valve block 2 as pilot oil. The first primary pressure passage 26 guides the primary pilot pressure generated by the primary pressure generating valve 30 of the sub-valve block 2 to the electromagnetic proportional pressure reducing valve 7. The first drain passage 27 discharges drain oil from the primary pressure generating valve 30 of the sub-valve block 2 to the tank 4.

As shown in Figure 2, the first inlet passage 25, the first primary pressure passage 26, and the first drain passage 27 are formed and open to the outer surface 1a of the main valve block 1. In addition, spool holes 1b that accommodate the spools of the multiple control valves 10 are also formed and open to the outer surface 1a of the main valve block 1.

1 and 3, the sub-valve block 2 is provided with a primary pressure generating valve 30, and a portion of the pilot passage 16 and the drain passage 17 are formed therein. As shown in FIG. 3, the sub-valve block 2 is attached via fastening members such as bolts, with its outer surface 2d in contact with the outer surface 1a, into which the first inlet passage 25, the first primary pressure passage 26, and the first drain passage 27 formed in the main valve block 1 open. The sub-valve block 2 has openings 2a, 2b, and 2c formed in the outer surface 2d that respectively communicate with the first inlet passage 25, the first primary pressure passage 26, and the first drain passage 27 formed in the main valve block 1.

The primary pressure generating valve 30 reduces the pressure of pilot oil introduced through the first inlet passage 25 of the main valve block 1 to generate primary pilot pressure and introduces it to the first primary pressure passage 26 of the main valve block 1. As shown in Figures 1 and 3, the primary pressure generating valve 30 has a second inlet passage 35 formed in the sub-valve block 2 and communicable with the first inlet passage 25 through opening 2a (see Figure 3), a second primary pressure passage 36 formed in the sub-valve block 2 and communicable with the first primary pressure passage 26 through opening 2b (see Figure 3), and a second drain passage 37 formed in the sub-valve block 2 and communicable with the first drain passage 27 through opening 2c (see Figure 3).

The second inlet passage 35 is part of the pilot passage 16 and guides a portion of the hydraulic oil discharged from the hydraulic pump 5 to the primary pressure generating valve 30 as pilot oil. That is, a portion of the hydraulic oil discharged from the hydraulic pump 5 is guided to the primary pressure generating valve 30 via the first inlet passage 25 of the main valve block 1 and the second inlet passage 35 of the sub-valve block 2. The second primary pressure passage 36 is part of the pilot passage 16 and guides the primary pilot pressure generated by the primary pressure generating valve 30 to the electromagnetic proportional pressure reducing valve 7 via the first primary pressure passage 26 of the main valve block 1. The second drain passage 37 is part of the drain passage 17 and discharges drain oil from the primary pressure generating valve 30 to the tank 4 via the first drain passage 27 of the main valve block 1.

Next, we will explain the configuration for generating primary pressure by the primary pressure generating valve 30. As shown in Figure 3, the primary pressure generating valve 30 has a first valve housing bore 41 through which the second inlet passage 35 and the second primary pressure passage 36 communicate, a second valve housing bore 42 which communicates with the first valve housing bore 41, a spool 50 which serves as a valve body housed across the first valve housing bore 41 and the second valve housing bore 42 and controls the flow of pilot oil from the second inlet passage 35 to the second primary pressure passage 36, a spring 60 which serves as a biasing member housed in the second valve housing bore 42 and biases the spool 50 toward the first valve housing bore 41, and a spring seat 70 on which the spring 60 sits.

The first valve housing hole 41 opens to the outer surface of the sub-valve block 2, and this opening is sealed by a first plug 61. The second valve housing hole 42 is formed to be continuous with the first valve housing hole 41, extend coaxially with the first valve housing hole 41, and is formed with a larger diameter than the first valve housing hole 41. The second valve housing hole 42 opens to the outer surface of the sub-valve block 2, and this opening is sealed by a second plug 62. The second valve housing hole 42 is in communication with the second drain passage 37.

The first valve housing hole 41 has a main housing hole 41a through which the spool 50 (specifically, the main body portion 51 described below) slides, and a first sub-housing hole 41b and a second sub-housing hole 41c, each having a larger inner diameter than the main housing hole 41a. The main housing hole 41a, first sub-housing hole 41b, and second sub-housing hole 41c are formed to extend coaxially. The first sub-housing hole 41b communicates with the second primary pressure passage 36, and the second sub-housing hole 41c communicates with the second introduction passage 35. The first sub-housing hole 41b corresponds to the "sub-housing hole" in the claims.

The spool 50 is slidably mounted in the first valve housing bore 41. The spring seat 70 has a flange 71 on which the spring 60 seats and a spring guide 72 against whose outer peripheral surface the spring 60 abuts and guides the spring 60, and is housed in the second valve housing bore 42. In the spring seat 70, the flange 71 and spring guide 72 are integrally formed. The spool 50 is fitted into a recess 71a formed in the center of the flange 71 and connected to the spring seat 70. Therefore, the portion of the spool 50 fitted into the recess 71a is housed in the second valve housing bore 42, and the other portion is housed in the first valve housing bore 41. In this embodiment, the spring 60 seats on the flange 71 of the spring seat 70, and the spool 50 is connected to the flange 71, so that the spool 50 is biased by the spring 60 via the flange 71. Furthermore, the end portion 50a of the spool 50 is seated on the first plug 61. In this state, the flange portion 71 of the spring seat 70 is seated on the bottom surface 42a of the second valve housing hole 42. Note that the spool 50 may be arranged so that a gap exists between the flange portion 71 and the bottom surface 42a of the second valve housing hole 42 when the end portion 50a is seated on the first plug 61.

The spool 50 has a main body 51 that can slide within the first valve housing bore 41, an internal spool passage 53 formed within the spool 50 and serving as an internal passage for the valve body that connects the second inlet passage 35 and the second primary pressure passage 36, a first orifice 54 that is provided in the internal spool passage 53 and serves as a throttle that applies resistance to the pilot oil passing through, and a second orifice 55 that is provided in the internal spool passage 53 closer to the flange 52 than the first orifice 54. In this embodiment, the spool 50 is formed with a uniform outer diameter.

The spool passage 53 extends axially through the main body 51 and opens at the end 50a of the spool 50. Multiple first and second orifices 54 and 55 extend radially within the spool 50 and open to the outer circumferential surface of the spool 50. The first and second orifices 54 and 55 have smaller diameters and larger equivalent areas than the spool passage 53. When the end 50a of the spool 50 is seated on the first plug 61, the first orifice 54 communicates with the second inlet passage 35, while the second orifice 55 does not communicate with the second inlet passage 35 or the second valve housing bore 42. The distance between the first orifice 54 and the second orifice 55 is smaller than the distance between the second sub-housing 41c and the second valve housing bore 42.

The spool 50 moves due to the balance between the load caused by the pressure of the pilot oil downstream of the first orifice 54 in the spool internal passage 53 and the biasing force of the spring 60. Depending on the movement of the spool 50, the second primary pressure passage 36 communicates with the second inlet passage 35 or the second drain passage 37 through the spool internal passage 53. As shown in FIG. 3, when the fluid pressure control device 100 is not in operation, the biasing force of the spring 60 causes the end 50a of the spool 50 to seat on the first plug 61. In this state, the first inlet passage 25 and the second primary pressure passage 36 communicate with each other through the grooves 50b formed radially extending from the spool internal passage 53 and the end 50a of the spool 50.

When the fluid pressure control device 100 is activated, a portion of the hydraulic oil discharged from the hydraulic pump 5 is gradually introduced as pilot oil from the supply passage 20 through the first inlet passage 25, the second inlet passage 35, and the first orifice 54 into the spool passage 53. This increases the pressure downstream of the first orifice 54 in the spool passage 53. This causes the spool 50 to move to the right in FIG. 3 against the biasing force of the spring 60, and the end 50a of the spool 50 disengages from the first plug 61. In this state, pilot oil from the second inlet passage 35 is introduced into the second primary pressure passage 36 through the spool passage 53 and reduced in pressure by the first orifice 54. This generates primary pilot pressure in the primary pressure generating valve 30. The primary pilot pressure is introduced to the electromagnetic proportional pressure reducing valve 7 through the second primary pressure passage 36 and the first primary pressure passage 26. The electromagnetic proportional pressure reducing valve 7 generates secondary pilot pressure and introduces it into the pilot pressure chamber 11. This controls the control valve 10.

In the fluid pressure control device 100, the pressure of the pilot oil introduced to the primary pressure generating valve 30 varies depending on the operating state of the multiple hydraulic cylinders 6. Specifically, when there are few operating hydraulic cylinders 6, the hydraulic fluid supplied from the hydraulic pump 5 to the hydraulic cylinders 6 decreases, causing the pressure of the pilot oil introduced to the primary pressure generating valve 30 to increase. As the pressure of the pilot oil introduced to the primary pressure generating valve 30 increases, the pressure downstream of the first orifice 54 in the spool passage 53 also increases, causing the spool 50 to move to the right in FIG. 3 against the biasing force of the spring 60. When the pressure downstream of the first orifice 54 in the spool passage 53 exceeds a predetermined pressure, the first orifice 54 first loses communication with the second inlet passage 35, as shown in FIG. 4, and communication between the second inlet passage 35 and the second primary pressure passage 36 is blocked.

Immediately after this, as shown in FIG. 5, the second orifice 55 communicates with the second valve housing bore 42, and the in-spool passage 53 and the second drain passage 37 communicate through the second valve housing bore 42. This allows pilot oil in the in-spool passage 53 to be discharged to the tank 4 through the second drain passage 37 and the first drain passage 27. At this time, the second orifice 55 prevents the pressure in the in-spool passage 53 from decreasing more than necessary. In this way, the increase in primary pilot pressure is suppressed. Subsequently, when the pressure downstream of the first orifice 54 in the in-spool passage 53 falls below a predetermined pressure, the spool 50 moves to the left in FIG. 3 due to the biasing force of the spring 60, blocking communication between the second orifice 55 and the second valve housing bore 42. The first orifice 54 reconnects to the second inlet passage 35, and the second inlet passage 35 reconnects to the second primary pressure passage 36 through the in-spool passage 53. In this way, the decrease in primary pilot pressure is suppressed. Furthermore, since the distance between the first orifice 54 and the second orifice 55 is smaller than the distance between the second sub-accommodating hole 41c and the second valve accommodating hole 42, the second inlet passage 35 and the second drain passage 37 do not communicate with each other through the spool internal passage 53 and the second valve accommodating hole 42.

In this way, even if the pressure of the pilot oil introduced to the primary pressure generating valve 30 changes, the primary pressure generating valve 30 blocks communication between the spool intra-passage 53 and the second inlet passage 35, and then the spool intra-passage 53 communicates with the second valve housing hole 42, suppressing an increase in the pressure of the pilot oil in the spool intra-passage 53. Therefore, even if the pressure of the pilot oil introduced to the primary pressure generating valve 30 changes, the primary pilot pressure introduced to the first and second primary pressure passages 26, 36 can be kept constant. The positions and sizes of the first and second restrictors 54, 55, the spring constant of the spring 60, and other factors are designed according to the set pressure of the primary pilot pressure.

As described above, in the fluid pressure control device 100, the sub-valve block 2 is attached to the main valve block 1, a portion of the hydraulic oil discharged from the hydraulic pump 5 is introduced to the sub-valve block 2 through the first inlet passage 25, and the primary pilot pressure generated by the primary pressure generating valve 30 in the sub-valve block 2 is introduced to the main valve block 1 through the first primary pressure passage 26. In the fluid pressure control device 100, the primary pressure generating valve 30 is provided in the sub-valve block 2 rather than the main valve block 1, which simplifies the oil passage in the main valve block 1 and prevents the main valve block 1 from becoming larger.

Furthermore, the fluid pressure control device 100 can also be used with the sub-valve block 2 removed. Specifically, the sub-valve block 2 is removed from the main valve block 1. Then, as shown in FIG. 6 , the openings of the first inlet passage 25 and the first drain passage 27 of the main valve block 1 are blocked with a plug 80, and a pilot pump 90 is connected to the first primary pressure passage 26 of the main valve block 1. This allows the discharge pressure of the pilot pump 90 to be directed to the electromagnetic proportional pressure reducing valve 7 as the primary pilot pressure. In this way, the fluid pressure control device 100 can direct the discharge pressure of the pilot pump 90 to the fluid pressure control device 100 as the primary pilot pressure as needed, depending on the user's needs. Therefore, the main valve block 1 can be used in common regardless of whether or not the pilot pump 90 is included.

Furthermore, when the fluid pressure control device 100 is used with the sub-valve block 2 attached, the hydraulic oil discharged from the hydraulic pump 5 is guided to the primary pressure generating valve 30 to generate primary pilot pressure. Therefore, there is no need to provide a pilot pump separate from the hydraulic pump 5 to generate primary pilot pressure, reducing the manufacturing costs of the fluid pressure control device 100.

The above-described embodiment provides the following effects:

In the fluid pressure control device 100, when the sub-valve block 2 is attached to the main valve block 1, a portion of the hydraulic oil discharged from the hydraulic pump 5 is introduced to the sub-valve block 2 as pilot oil through the first inlet passage 25, and the primary pilot pressure generated by the primary pressure generating valve 30 in the sub-valve block 2 is introduced to the main valve block 1 through the first primary pressure passage 26. In this way, in the fluid pressure control device 100, the primary pressure generating valve 30 is provided in the sub-valve block 2 rather than the main valve block 1, which simplifies the oil passages in the main valve block 1 and prevents the main valve block 1 from becoming larger. On the other hand, by removing the sub-valve block 2 from the main valve block 1, blocking the openings of the first inlet passage 25 and the first drain passage 27 of the main valve block 1 with a plug 80, and connecting a pilot pump 90 to the first primary pressure passage 26, the discharge pressure of the pilot pump 90 can be introduced to the electromagnetic proportional pressure reducing valve 7 as primary pilot pressure. This allows the main valve block 1 to be used in a standardized manner, regardless of whether or not the pilot pump 90 is installed.

In the fluid pressure control device 100, even if the pressure of the pilot oil introduced to the primary pressure generating valve 30 increases, the communication between the spool in-passage 53 and the second inlet passage 35 is blocked in the primary pressure generating valve 30, and then the spool in-passage 53 communicates with the second valve housing bore 42, reducing the pressure of the pilot oil in the spool in-passage 53. Therefore, regardless of the magnitude of the pressure of the pilot fluid introduced through the second inlet passage 35, the primary pilot pressure introduced to the electromagnetic proportional pressure reducing valve 7 through the second primary pressure passage 26 can be kept constant.

Next, we will explain modified examples of this embodiment. The following modifications are also within the scope of the present invention, and it is also possible to combine the following modifications with each configuration of the above embodiment.

<Modification>
In the above embodiment, the spool 50 has a main body portion 51 and is formed with a uniform outer diameter. However, as shown in FIG. 7 , the spool 50 may further include, in addition to the main body portion 51, a large diameter portion 58 formed with a diameter larger than that of the main body portion 51. The large diameter portion 58 is housed in the first sub-housing hole 41b. The first sub-housing hole 41b is divided by the large diameter portion 58 into a primary pressure chamber 39 that communicates with the second primary pressure passage 26, and a damper chamber 40 that communicates with the primary pressure chamber 39. The damper chamber 40 is expanded and contracted by the large diameter portion 58 as the spool 50 moves. The damper chamber 40 is provided on the second valve housing hole 42 side of the first sub-housing hole 41b (the right side in FIG. 7 ).

The large diameter portion 58 is positioned so that when the pressure of the pilot oil guided to the primary pressure generating valve 30 increases, it does not contact the inner wall 40a of the damper chamber 40 until the spool in-passage 53 and the second drain passage 37 are connected through the second valve housing bore 42, as shown in FIG. 5. Specifically, when the end 50a of the spool 50 is seated on the first plug 61, the distance between the large diameter portion 58 and the inner wall 40a is greater than the distance between the second orifice 55 and the second valve housing bore 42. Furthermore, the large diameter portion 58 is positioned so that when the end 50a of the spool 50 is seated on the first plug 61, the damper chamber 40 does not directly communicate with the second primary pressure passage 36.

The outer diameter of the large diameter portion 58 is slightly smaller than the inner diameter of the first sub-housing 41b. Therefore, a gap 59 is formed between the outer surface of the large diameter portion 58 and the inner surface of the first sub-housing 41b. The damper chamber 40 is connected to the primary pressure chamber 39 through the gap 59, so pilot fluid is supplied to and discharged from the damper chamber 40 as the spool 50 moves.

Specifically, when the fluid pressure control device 100 is in standby mode, pilot fluid is introduced into the spool in-passage 53 through the second inlet passage 35, and pilot fluid is supplied from the primary pressure chamber 39 to the damper chamber 40 through the gap 59. When the fluid pressure control device 100 is activated and the pressure in the second inlet passage 35 increases, the spool 50 moves to the right in FIG. 7 against the biasing force of the spring 60. At this time, the pilot fluid in the damper chamber 40 is discharged into the primary pressure chamber 39 through the gap 59. When the second restrictor 55 communicates with the second valve housing bore 42 and the pressure in the spool in-passage 53 and the second inlet passage 35 decreases, the spool 50 moves to the left in FIG. 7 due to the biasing force of the spring 60, and pilot fluid is supplied from the primary pressure chamber 39 to the damper chamber 40 through the gap 59.

In this manner, in this modified example, the large diameter portion 58 defines the damper chamber 40. When the pressure in the second inlet passage 35 increases, the spool 50 moves while discharging pilot fluid from the damper chamber 40 into the primary pressure chamber 39. This reduces the amount of movement of the spool 50 compared to when the spool 50 does not have the large diameter portion 58. Therefore, even if the pressure in the second inlet passage 35 increases suddenly, the spool 50 is prevented from moving suddenly, and the opening area of the spool in-passage 53 (second orifice 55) that opens to the second valve housing bore 42 does not increase suddenly. This prevents the pressure in the second primary pressure passage 36 from decreasing more than necessary and suppresses hunting of the spool 50.

In this modified example, the primary pressure chamber 39 opens to the outer surface of the sub-valve block 2, and during assembly, the spool 50 is attached through this opening, with the large diameter portion 58 housed in the first sub-accommodation bore 41b. In addition, in this modified example, the second inlet passage 35 and the second primary pressure passage 36 communicate with each other through a third orifice 56 located in the spool inner passage 53 closer to the end 50a than the first orifice 54. This reduces pressure loss compared to when the second inlet passage 35 and the second primary pressure passage 36 communicate with each other through the groove 50b (see Figures 3 to 5).

The configuration, operation, and effects of the embodiment of the present invention configured as described above will now be explained.

The fluid pressure control device 100 controls a hydraulic cylinder 6 as an actuator driven by working fluid discharged from a hydraulic pump 5 as a pump. It comprises a control valve 10 that controls the flow of working fluid supplied to and discharged from the hydraulic cylinder 6, an electromagnetic proportional pressure reducing valve 7 as a solenoid valve that generates pilot pressure to control the control valve 10, a main valve block 1 in which the control valve 10 and the electromagnetic proportional pressure reducing valve 7 are provided, and a sub-valve block 2 that is detachably provided to the main valve block 1. The main valve block 1 has a supply passage 20 that supplies working fluid discharged from the hydraulic pump 5, and a branch in the supply passage 20 upstream of the control valve 10 that guides a portion of the fluid discharged from the hydraulic pump 5 to the sub-valve block 2 as pilot fluid. a first inlet passage 25 through which the primary pilot pressure can be introduced, a first primary pressure passage 26 through which the primary pilot pressure can be introduced from the sub-valve block 2 or the pilot pump 90 to the electromagnetic proportional pressure reducing valve 7, and a first drain passage 27 through which drain fluid from the sub-valve block 2 can be discharged to the tank 4; the first inlet passage 25, the first primary pressure passage 26 and the first drain passage 27 are formed and open to the outer surface 1a of the main valve block 1; the sub-valve block 2 has openings 2a, 2b and 2c formed on its outer surface 2d which can be communicated with the first inlet passage 25, the first primary pressure passage 26 and the first drain passage 27, respectively, and is provided with a primary pressure generating valve 30 which can reduce the pressure of the pilot fluid introduced through the first inlet passage 25 to generate a primary pilot pressure and introduce it to the first primary pressure passage 26.

In this configuration, when the sub-valve block 2 is attached to the main valve block 1, a portion of the hydraulic fluid discharged from the hydraulic pump 5 is introduced to the sub-valve block 2 as pilot fluid through the first inlet passage 25, and primary pilot pressure generated by the primary pressure generating valve 30 of the sub-valve block 2 is introduced to the main valve block 1 through the first primary pressure passage 26. In this way, in the fluid pressure control device 100, the primary pressure generating valve 30 is provided in the sub-valve block 2 rather than the main valve block 1, simplifying the oil passages in the main valve block 1 and preventing the main valve block 1 from becoming larger. On the other hand, by removing the sub-valve block 2 from the main valve block 1, plugging the openings of the first inlet passage 25 and the first drain passage 27 of the main valve block 1 with a plug or the like, and connecting the pilot pump 90 to the first primary pressure passage 26, the discharge pressure of the pilot pump 90 can be introduced to the electromagnetic proportional pressure reducing valve 7 as primary pilot pressure. This allows the main valve block 1 to be used in a common configuration regardless of whether or not the pilot pump 90 is included.

In the fluid pressure control device 100, the primary pressure generating valve 30 has a second inlet passage 35 formed in the sub-valve block 2 and communicable with the first inlet passage 25 through opening 2a, a second primary pressure passage 36 formed in the sub-valve block 2 and communicable with the first primary pressure passage 26 through opening 2b, a first valve accommodating hole 41 through which the second inlet passage 35 and the second primary pressure passage 36 communicate, and a spool 50 as a valve body, a portion of which is accommodated in the first valve accommodating hole 41 and controls the flow of fluid from the second inlet passage 35 to the second primary pressure passage 36. The spool 50 has an intra-spool passage 53 formed within the spool 50 as an internal passage within the valve body that communicates between the second inlet passage 35 and the second primary pressure passage 36, and a first orifice 54 provided in the intra-spool passage 53 as a orifice that applies resistance to the fluid passing through.

In this configuration, the fluid discharged from the hydraulic pump 5 is reduced in pressure by the first throttle 54 provided in the spool passage 53, generating a primary pilot pressure that is guided to the electromagnetic proportional pressure reducing valve 7.

In the fluid pressure control device 100, the primary pressure generating valve 30 further includes a second drain passage 37 formed in the sub-valve block 2 and capable of communicating with the first drain passage 27 through the opening 2c, a second valve accommodating hole 42 that communicates with the first valve accommodating hole 41 and accommodates a portion of the spool 50, and a spring 60 that is accommodated in the second valve accommodating hole 42 and serves as a biasing member that biases the spool 50 toward the first valve accommodating hole 41. The spool 50 moves due to the balance between the pressure of the fluid downstream of the first orifice 54 in the spool intra-passage 53 and the biasing force of the spring 60, and the second primary pressure passage 36 communicates with the second inlet passage 35 or the second drain passage 37 through the spool intra-passage 53 depending on the movement of the spool 50.

With this configuration, the primary pilot pressure led to the electromagnetic proportional pressure reducing valve 7 through the second primary pressure passage 36 can be kept constant regardless of the pressure of the pilot fluid led through the second inlet passage 35.

In addition, in the fluid pressure control device 100, the spool 50 further has a main body portion 51 and a large diameter portion 58 formed with a larger diameter than the main body portion 51, and the first valve accommodating hole 41 has a main accommodating hole 41a in which the main body portion 51 slides and a first sub-accommodating hole 41b as a sub-accommodating hole having an inner diameter larger than that of the main accommodating hole 41a and in which the large diameter portion 58 is accommodated, and the first sub-accommodating hole 41b is partitioned into a primary pressure chamber 39 communicating with the second primary pressure passage 36 and a damper chamber 40 communicating with the primary pressure chamber 39 and expanded and contracted by the large diameter portion 58 as the spool 50 moves.

With this configuration, the amount of movement of the spool 50 is reduced compared to when the spool 50 does not have the large diameter portion 58. Therefore, even if the pressure in the second inlet passage 35 rises suddenly, the spool 50 is prevented from moving suddenly, preventing the pressure in the second primary pressure passage 36 from dropping more than necessary and suppressing hunting of the spool 50.

The above describes embodiments of the present invention, but the above embodiments merely illustrate some of the application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

This application claims priority to Patent Application No. 2022-191551, filed with the Japan Patent Office on November 30, 2022, the entire contents of which are incorporated herein by reference.

Claims (4)

A fluid pressure control device that controls an actuator driven by a working fluid discharged from a pump,
a control valve for controlling the flow of working fluid supplied to and discharged from the actuator;
a solenoid valve for generating a pilot pressure for controlling the control valve;
a main valve block in which the control valve and the solenoid valve are provided;
a sub-valve block detachably provided on the main valve block,
The main valve block includes:
a supply passage for supplying the working fluid discharged from the pump;
a first introduction passage that branches off from the supply passage at a position upstream of the control valve and that is capable of introducing a portion of the fluid discharged from the pump as a pilot fluid to the sub-valve block;
a first primary pressure passage that introduces a primary pilot pressure from the sub-valve block or the pilot pump to the solenoid valve;
a first drain passage through which drain fluid from the sub-valve block can be discharged to a tank;
the first introduction passage, the first primary pressure passage, and the first drain passage are formed to open to an outer surface of the main valve block,
The sub-valve block has openings formed on its outer surface that can be connected to the first inlet passage, the first primary pressure passage, and the first drain passage, respectively, and is provided with a primary pressure generating valve that can reduce the pressure of pilot fluid introduced through the first inlet passage to generate a primary pilot pressure and introduce it into the first primary pressure passage. The fluid pressure control device according to claim 1,
The primary pressure generating valve is
a second introduction passage formed in the sub-valve block and capable of communicating with the first introduction passage through the opening;
a second primary pressure passage formed in the sub-valve block and capable of communicating with the first primary pressure passage through the opening;
a first valve housing hole through which the second introduction passage and the second primary pressure passage communicate with each other;
a valve element, a portion of which is accommodated in the first valve accommodation hole, for controlling the flow of fluid from the second introduction passage to the second primary pressure passage,
The valve body is
a valve body passage formed within the valve body and capable of communicating the second introduction passage with the second primary pressure passage;
a throttle provided in the valve body passage and providing resistance to the fluid passing through. The fluid pressure control device according to claim 2,
The primary pressure generating valve is
a second drain passage formed in the sub-valve block and capable of communicating with the first drain passage through the opening;
a second valve housing hole communicating with the first valve housing hole and housing a portion of the valve body;
a biasing member that is accommodated in the second valve housing hole and biases the valve element toward the first valve housing hole,
the valve body moves due to a balance between the pressure of the fluid downstream of the throttle in the valve body passage and the biasing force of the biasing member,
The second primary pressure passage is in communication with the second introduction passage or the second drain passage through the valve body internal passage in accordance with movement of the valve body. The fluid pressure control device according to claim 2,
The valve body is
a main body;
a large diameter portion formed to have a diameter larger than that of the main body portion,
The first valve receiving hole is
a main accommodating hole in which the main body slides;
a sub-accommodating hole having an inner diameter larger than that of the main accommodating hole and configured to accommodate the large diameter portion;
a sub-accommodating hole that is partitioned into a primary pressure chamber that communicates with the second primary pressure passage, and a damper chamber that communicates with the primary pressure chamber and is expanded and contracted by the large diameter portion as the valve body moves.