Fluid Pressure Control Device

Abstract

Provided is a fluid pressure control device (100) comprising a main valve block (1), and a sub-valve block (2). The main valve block (1) is formed with a supply passage (20), a first introduction passage (25), a first primary pressure passage (26), and a first drain passage (27). The first introduction passage (25), the first primary pressure passage (26), and the first drain passage (27) are formed to open on an outer surface (1a) of the main valve block (1). The sub-valve block (2) has openings (2a, 2b, 2c) formed on an outer surface (2d) and capable of communicating with the first introduction passage (25), the first primary pressure passage (26), and the first drain passage (27), respectively, and is provided with a primary pressure generation valve (30) capable of generating a primary pilot pressure, and guiding the primary pilot pressure to the first primary pressure passage (26).

Description

[Technical Field]

[0001] The present invention relates to a fluid pressure control device. [Background technology]

[0002] JP2019-94973A discloses a construction machine such as a hydraulic excavator, which includes 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 an 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) for moving the spool is introduced. The construction machine also has 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 receives the primary pressure and controls the pressure (secondary pressure) acting on the pilot port, and the spool is moved when pilot oil is supplied to the pilot port. Summary of the Invention

[0003] In construction machinery such as that described in JP2019-94973A, the discharge pressure of the hydraulic pump is reduced by a pressure reducing valve to generate primary pressure, the pilot oil at the primary pressure is directed to an electromagnetic proportional pressure reducing valve to generate secondary pressure, and the pilot oil at the secondary pressure is directed to a pilot chamber. However, if the pressure reducing valve is provided inside the housing of the control valve, the oil passage becomes complicated and the housing becomes larger.

[0004] Furthermore, in construction machinery such as that described in JP2019-94973A, the discharge pressure of the pilot pump may be directly led to the electromagnetic proportional pressure reducing valve as the primary pressure depending on the needs of the user. However, if the pressure reducing valve is provided inside the housing of the control valve, it is difficult to form an oil passage that leads only the discharge pressure of the pilot pump to the electromagnetic proportional pressure reducing valve, making it difficult to directly lead the discharge pressure of the pilot pump to the electromagnetic proportional pressure reducing valve.

[0005] An object of the present invention is to provide a fluid pressure control device that prevents the housing from becoming large and enables the discharge pressure of a pilot pump to be introduced as a primary pressure to a solenoid valve as required. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a fluid pressure control device for controlling an actuator driven by a working fluid discharged from a pump, the fluid pressure control device comprising: a control valve for controlling the flow of working fluid supplied to or 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; and a sub-valve block detachably provided on the main valve block, the main valve block comprising a supply passage for supplying the working fluid discharged from the pump; The main valve block is provided with 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. The first inlet passage, the first primary pressure passage, and the first drain passage are formed to open onto the outer surface of the main valve block. 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 into the first primary pressure passage. [Brief explanation of the drawings]

[0007] [Figure 1] 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. [Figure 2]FIG. 2 is a side view showing the mounting surface of the main valve block to which the sub-valve block is attached. [Figure 3] FIG. 3 is a cross-sectional view of the sub-valve block, showing the state in which the spool is seated on the first plug. [Figure 4] FIG. 4 is a cross-sectional view of the sub-valve block, showing the spool separated from the first plug. [Figure 5] 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. [Figure 6] 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. [Figure 7] 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. DETAILED DESCRIPTION OF THE INVENTION

[0008] A fluid pressure control device 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0009] The fluid pressure control device 100 is a device that controls actuators driven by working fluid discharged from a pump, and is mounted on work machines such as construction machines, agricultural machines, and industrial machines. The following describes a case in which 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 a boom, arm, bucket, etc. Note that, although an example in which hydraulic oil is used as the working fluid to drive the actuators of a hydraulic excavator will be described, other fluids such as working water may also be used as the working fluid.

[0010] First, the overall configuration of a fluid pressure control device 100 will be described with reference to the fluid pressure circuit diagram of FIG.

[0011] The fluid pressure control device 100 includes a variable displacement hydraulic pump 5 as a pump, a hydraulic cylinder 6 as an actuator driven by hydraulic oil discharged from the hydraulic pump 5, a supply passage 20 that supplies the hydraulic oil discharged from the hydraulic pump 5, a control valve 10 that is provided in the supply passage 20 and controls the flow of hydraulic oil supplied to and discharged from the hydraulic cylinder 6, a pair of actuator passages 21 that are connected to the control valve 10 and the hydraulic cylinder 6 and through which hydraulic oil supplied to and discharged from the hydraulic cylinder 6 flows, and a discharge passage 22 that is connected to the control valve 10 and a tank 4 and through which hydraulic oil discharged from the hydraulic cylinder 6 flows to the tank 4. A plurality of hydraulic cylinders 6 and control valves 10 are provided, and FIG. 1 shows one hydraulic cylinder 6 and two control valves 10a and 10b as representatives.

[0012] The hydraulic pump 5 is driven by an engine mounted on the hydraulic excavator. However, the hydraulic pump 5 is not limited to this and may be driven by an electric motor. The hydraulic cylinder 6 includes a cylinder tube 6a, a piston rod 6b inserted into the cylinder tube 6a, and a piston 6c provided at the end of the piston rod 6b and sliding along the inner circumferential 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.

[0013] 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.

[0014] The control valve 10 is a 4-port 3-position spool valve, and in this embodiment, a plurality of control valves 10 with a similar configuration are provided corresponding to each hydraulic cylinder 6. The control valve 10 switches its position by introducing secondary pilot pressure to a pair of pilot pressure chambers 11 through a pilot passage 16 (described later) in accordance with the direction and amount of operation of an operating lever 9 by an operator. The control valve 10 switches its position among a neutral position 10A, an extension position 10B, and a retraction position 10C in accordance with the magnitude of the secondary pilot pressure supplied to the pair of pilot pressure chambers 11. Control of the control valve 10 will be described in detail below.

[0015] 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 the pair of pilot pressure chambers 11, a primary pressure generating valve 30 provided in the pilot passage 16 and generating a 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 a solenoid valve for generating a 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.

[0016] The pilot passage 16 is provided by branching off from the supply passage 20 at a position 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 on the upstream side 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.

[0017] The primary pressure generating valve 30 reduces the pressure of the pilot oil guided from the hydraulic pump 5 to the pilot passage 16, and generates a primary pilot pressure that is guided to the electromagnetic proportional pressure reducing valve 7. The primary pressure generating valve 30 operates so that the primary pilot pressure is always constant, 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.

[0018] 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 is introduced to each of the two electromagnetic proportional pressure reducing valves 7, and a secondary pilot pressure is generated by the electromagnetic proportional pressure reducing valve 7 and introduced to each of the pair of pilot pressure chambers 11. This controls the control valve 10. Furthermore, discharge oil is discharged from the electromagnetic proportional pressure reducing valve 7 through a passage 18. The passage 18 is connected to a drain passage 17, and the discharge oil from the electromagnetic proportional pressure reducing valve 7 is discharged to the tank 4 through the passage 18 and the drain passage 17.

[0019] The controller 8 is configured by a microcomputer including a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read-Only Memory) that stores control programs executed by the CPU, etc., and a RAM (Random Access Memory) that stores the results of CPU calculations, etc. The controller 8 may be configured by a single microcomputer or may be configured by multiple microcomputers.

[0020] 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 no secondary pilot pressure is 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 do not communicate with 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 the 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.

[0021] 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 the secondary pilot pressure is introduced into 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 introduced from the hydraulic pump 5 to the rod-side chamber 6d, and the hydraulic cylinder 6 retracts. In this manner, the control valve 10a is controlled.

[0022] Next, the main valve block 1 and the sub-valve block 2 in which the above-mentioned fluid pressure circuit is formed will be described in detail.

[0023] The fluid pressure control device 100 includes a main valve block 1 and a sub-valve block 2 that is detachably mounted on the main valve block 1. FIG. 1 shows the area formed in the main valve block 1 and the area formed in the sub-valve block 2 in the fluid pressure circuit. As shown in FIG. 1, a pilot passage 16 is formed across the main valve block 1 and the sub-valve block 2, and a 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 not provided in the main valve block 1, but in the sub-block that is detachably mounted on the main valve block 1. This prevents the oil passages in the main valve block 1 from becoming complicated. This is explained in detail below.

[0024] 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 has a pilot passage 16 and a portion of a drain passage 17. Specifically, the main valve block 1 has 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 introduces primary pilot pressure generated by a 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 introduces 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 introduces 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 introduces 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 the drain oil from the primary pressure generating valve 30 of the sub-valve block 2 into the tank 4.

[0025] 2, the first introduction passage 25, the first primary pressure passage 26, and the first drain passage 27 are formed and open on the outer surface 1a of the main valve block 1. Also, spool holes 1b that accommodate the spools of the multiple control valves 10 are also formed and open on the outer surface 1a of the main valve block 1.

[0026] 1 and 3, the sub-valve block 2 is provided with a primary pressure generating valve 30, and a part of the pilot passage 16 and the drain passage 17 is formed in the sub-valve block 2. 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 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, respectively.

[0027] The primary pressure generating valve 30 is capable of reducing the pressure of pilot oil introduced through the first introduction passage 25 of the main valve block 1 to generate primary pilot pressure and introducing 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 introduction passage 35 formed in the sub-valve block 2 and capable of communicating with the first introduction passage 25 through an opening 2a (see Figure 3), a second primary pressure passage 36 formed in the sub-valve block 2 and capable of communicating with the first primary pressure passage 26 through an opening 2b (see Figure 3), and a second drain passage 37 formed in the sub-valve block 2 and capable of communicating with the first drain passage 27 through an opening 2c (see Figure 3).

[0028] The second inlet passage 35 is part of the pilot passage 16, and introduces a portion of the hydraulic oil discharged from the hydraulic pump 5 as pilot oil to the primary pressure generating valve 30. That is, a portion of the hydraulic oil discharged from the hydraulic pump 5 is introduced to the primary pressure generating valve 30 through 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 introduces the primary pilot pressure generated by the primary pressure generating valve 30 to the electromagnetic proportional pressure reducing valve 7 through 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 through the first drain passage 27 of the main valve block 1.

[0029] Next, a description will be given of the configuration for generating primary pressure by the primary pressure generating valve 30. As shown in Fig. 3, the primary pressure generating valve 30 has a first valve housing hole 41 through which the second introduction passage 35 and the second primary pressure passage 36 communicate, a second valve housing hole 42 which communicates with the first valve housing hole 41, a spool 50 which serves as a valve body housed across the first valve housing hole 41 and the second valve housing hole 42 and controls the flow of pilot oil from the second introduction passage 35 to the second primary pressure passage 36, a spring 60 which is housed in the second valve housing hole 42 and serves as an urging member which urges the spool 50 toward the first valve housing hole 41, and a spring seat 70 on which the spring 60 is seated.

[0030] 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 a second drain passage 37.

[0031] The first valve housing hole 41 has a main housing hole 41a in which the spool 50 (specifically, a main body portion 51 described below) slides, and a first sub-housing hole 41b and a second sub-housing hole 41c having an inner diameter larger than that of the main housing hole 41a. The main housing hole 41a, the first sub-housing hole 41b, and the 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.

[0032] The spool 50 is slidably disposed 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 whose outer peripheral surface the spring 60 contacts and guides the spring 60, and is housed in the second valve housing bore 42. In the spring seat 70, the flange 71 and the 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, with the end portion 50a seated on the first plug 61, a gap exists between the flange portion 71 and the bottom surface 42a of the second valve housing hole 42.

[0033] The spool 50 has a main body 51 that is slidable within the first valve housing hole 41, an intra-spool passage 53 that is formed within the spool 50 and serves as an internal passage within the valve body that is capable of communicating the second introduction passage 35 and the second primary pressure passage 36, a first orifice 54 that is provided in the intra-spool passage 53 and serves as a throttle that imparts resistance to the pilot oil passing therethrough, and a second orifice 55 that is provided in the intra-spool passage 53 on the flange 52 side of the first orifice 54. In this embodiment, the spool 50 is formed to have a uniform outer diameter.

[0034] The intra-spool passage 53 is formed in the main body 51, extending axially, and opens at the end 50a of the spool 50. A plurality of first and second orifices 54 and 55 are formed radially within the spool 50, and open at the outer circumferential surface of the spool 50. The first and second orifices 54 and 55 are formed to have smaller diameters than the intra-spool passage 53 and larger equivalent areas than the intra-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 introduction passage 35, but the second orifice 55 does not communicate with the second introduction passage 35 or the second valve housing hole 42. The distance between the first orifice 54 and the second orifice 55 is formed to be smaller than the distance between the second sub-housing hole 41c and the second valve housing hole 42.

[0035] 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 in-spool passage 53 and the biasing force of the spring 60. The second primary pressure passage 36 communicates with the second inlet passage 35 or the second drain passage 37 through the in-spool passage 53 in accordance with the movement of the spool 50. 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 50 a 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 in-spool passage 53 and grooves 50 b formed radially extending from the end 50 a of the spool 50.

[0036] 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 in-spool passage 53. This increases the pressure in the in-spool passage 53 downstream of the first orifice 54. 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 separates from the first plug 61. In this state, the pilot oil in the second inlet passage 35 is introduced into the second primary pressure passage 36 through the in-spool passage 53 while being reduced in pressure by the first orifice 54. This causes the primary pressure generating valve 30 to generate primary pilot pressure. 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.

[0037] In the fluid pressure control device 100, the pressure of the pilot oil guided to the primary pressure generating valve 30 changes depending on the operating states of the multiple hydraulic cylinders 6. Specifically, when there are few operating hydraulic cylinders 6, the amount of working fluid supplied from the hydraulic pump 5 to the hydraulic cylinders 6 decreases, causing the pressure of the pilot oil guided to the primary pressure generating valve 30 to increase. When the pressure of the pilot oil guided to the primary pressure generating valve 30 increases, the pressure downstream of the first orifice 54 in the spool intra-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 intra-passage 53 exceeds a predetermined pressure, first, as shown in FIG. 4, the first orifice 54 loses communication with the second introduction passage 35, blocking communication between the second introduction passage 35 and the second primary pressure passage 36.

[0038] 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 with each other through the second valve housing bore 42. As a result, pilot oil in the in-spool passage 53 is 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, an increase in primary pilot pressure is suppressed. Thereafter, 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 is reconnected to the second inlet passage 35, and the second inlet passage 35 is reconnected to the second primary pressure passage 36 through the in-spool passage 53. In this way, a 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.

[0039] In this way, even if the pressure of the pilot oil introduced to the primary pressure generating valve 30 changes, in the primary pressure generating valve 30, after the communication between the in-spool passage 53 and the second introduction passage 35 is blocked, the in-spool passage 53 communicates with the second valve housing hole 42, thereby suppressing an increase in the pressure of the pilot oil in the in-spool 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 throttles 54, 55, the spring constant of the spring 60, and the like are designed according to the set pressure of the primary pilot pressure.

[0040] 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 introduction passage 25, and the 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 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, so the oil passages in the main valve block 1 are simplified and it is possible to prevent the main valve block 1 from becoming larger.

[0041] 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 led to the electromagnetic proportional pressure reducing valve 7 as the primary pilot pressure. In this way, with the fluid pressure control device 100, the discharge pressure of the pilot pump 90 can be led to the fluid pressure control device 100 as the primary pilot pressure as needed, depending on the needs of the user. Therefore, the main valve block 1 can be used in common regardless of whether or not the pilot pump 90 is included.

[0042] 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, and the manufacturing costs of the fluid pressure control device 100 are reduced.

[0043] According to the above-described embodiment, the following advantageous effects are achieved.

[0044] 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 as pilot oil to the sub-valve block 2 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, 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 as primary pilot pressure to the electromagnetic proportional pressure reducing valve 7. Therefore, the main valve block 1 can be used in common regardless of whether or not the pilot pump 90 is provided.

[0045] 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 in-spool passage 53 and the second introduction passage 35 in the primary pressure generating valve 30 is blocked, and then the in-spool passage 53 communicates with the second valve housing hole 42, reducing the pressure of the pilot oil in the in-spool passage 53. Therefore, regardless of the magnitude of the pressure of the pilot fluid introduced through the second introduction 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.

[0046] Next, modifications of the present embodiment will be described. The following modifications are also within the scope of the present invention, and it is also possible to combine the following modifications with the respective configurations of the above embodiment.

[0047] <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 have, 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 ).

[0048] The large diameter portion 58 is positioned so as not to come into contact with the inner wall 40a of the damper chamber 40 when the pressure of the pilot oil guided to the primary pressure generating valve 30 increases until the in-spool passage 53 and the second drain passage 37 are connected to each other through the second valve housing hole 42, as shown in FIG. 5 . Specifically, when the end portion 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 hole 42. Furthermore, the large diameter portion 58 is formed so that the damper chamber 40 does not directly communicate with the second primary pressure passage 36 when the end portion 50a of the spool 50 is seated on the first plug 61.

[0049] The outer diameter of the large diameter portion 58 is formed slightly smaller than the inner diameter of the first sub-housing hole 41b. Therefore, a gap 59 is formed between the outer peripheral surface of the large diameter portion 58 and the inner peripheral surface of the first sub-housing hole 41b. The damper chamber 40 communicates with the primary pressure chamber 39 through the gap 59, so that pilot fluid is supplied to and discharged from the damper chamber 40 as the spool 50 moves.

[0050] Specifically, when pilot fluid is introduced into the in-spool passage 53 through the second introduction passage 35 while the fluid pressure control device 100 is on standby, pilot fluid is supplied from the primary pressure chamber 39 through the gap 59 to the damper chamber 40. When the fluid pressure control device 100 is activated and the pressure in the second introduction 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 hole 42 and the pressure in the in-spool passage 53 and the second introduction 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 through the gap 59 to the damper chamber 40.

[0051] As described above, in this modified example, the large diameter portion 58 defines the damper chamber 40, and when the pressure in the second introduction passage 35 increases, the spool 50 moves while discharging pilot fluid from the damper chamber 40 into the primary pressure chamber 39. Therefore, 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 introduction passage 35 increases suddenly, the spool 50 is prevented from moving suddenly, and the opening area of ​​the in-spool passage 53 (second orifice 55) that opens to the second valve housing hole 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.

[0052] 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-accommodating hole 41b. Also, in this modified example, the second introduction passage 35 and the second primary pressure passage 36 communicate with each other through a third orifice 56 that is provided in the spool intra-passage 53 closer to the end 50a than the first orifice 54. This reduces pressure loss compared to when the second introduction passage 35 and the second primary pressure passage 36 communicate with each other through the groove 50b (see FIGS. 3 to 5).

[0053] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0054] A fluid pressure control device 100 controls a hydraulic cylinder 6 as an actuator driven by a working fluid discharged from a hydraulic pump 5 as a pump, and comprises: a control valve 10 that controls the flow of the working fluid supplied to and discharged from the hydraulic cylinder 6; an electromagnetic proportional pressure reducing valve 7 as a solenoid valve that generates a 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 on the main valve block 1. The main valve block 1 has a supply passage 20 that supplies the 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 a pilot fluid. a first inlet passage 25 capable of reducing the pressure in the pilot valve block 2, a first primary pressure passage 26 that introduces primary pilot pressure 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 that can discharge drain fluid from the sub-valve block 2 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 an outer surface 1a of the main valve block 1; the sub-valve block 2 has openings 2a, 2b, and 2c formed on an outer surface 2d thereof that can communicate 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 that can reduce the pressure of the pilot fluid introduced through the first inlet passage 25 to generate primary pilot pressure and introduce it to the first primary pressure passage 26.

[0055] In this configuration, when the sub-valve block 2 is attached to the main valve block 1, a portion of the working fluid discharged from the hydraulic pump 5 is introduced as pilot fluid to the sub-valve block 2 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, 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 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 as primary pilot pressure to the electromagnetic proportional pressure reducing valve 7. Therefore, the main valve block 1 can be used in common regardless of whether or not the pilot pump 90 is provided.

[0056] Furthermore, 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 capable of communicating with the first inlet passage 25 through an opening 2a, a second primary pressure passage 36 formed in the sub-valve block 2 and capable of communicating with the first primary pressure passage 26 through an 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 that is partially 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, and the spool 50 has an intra-spool passage 53 formed within the spool 50 as an internal passage within the valve body that is capable of communicating 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.

[0057] In this configuration, the fluid discharged from the hydraulic pump 5 is reduced in pressure by the first throttle 54 provided in the in-spool passage 53, and a primary pilot pressure that is guided to the electromagnetic proportional pressure reducing valve 7 can be generated.

[0058] Furthermore, 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, and 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 introduction passage 35 or the second drain passage 37 through the spool intra-passage 53 depending on the movement of the spool 50.

[0059] In this configuration, regardless of the magnitude of the pressure of the pilot fluid introduced through the second introduction passage 35, the primary pilot pressure introduced to the electromagnetic proportional pressure reducing valve 7 through the second primary pressure passage 36 can be kept constant.

[0060] Furthermore, 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 accommodating the large diameter portion 58, 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.

[0061] In 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 introduction 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.

[0062] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0063] This application claims priority based on Japanese 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

1. 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.

2. 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.

3. 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.

4. 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.

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