JP7026005B2 - Fluid pressure controller - Google Patents

Description

The present invention relates to a fluid pressure control device.

A hydraulic control circuit that controls the operation of the actuator by providing a plurality of actuator control valves between the plurality of actuators and the hydraulic pump driven by the engine, and controlling the supply and discharge of hydraulic oil to the actuator by the actuator control valve. (See Patent Document 1).

Japanese Patent Application Laid-Open No. 2003-4005

In the construction machine described in Patent Document 1, oil leakage, oil splash, etc. may occur due to the residual pressure of the actuator during the dismantling work of removing the actuator from the construction machine. Therefore, it is necessary to reduce the pressure in the actuator in advance. However, in the construction machine described in Patent Document 1, in order to reduce the pressure in the actuator, it is necessary to provide an accessory such as a dedicated pressure relief device, which causes a problem that the number of parts and the cost increase. there were.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent oil leakage, oil splash, etc. during dismantling work of an actuator without increasing the number of parts and cost. ..

The first invention is a fluid pressure control device including a plurality of actuator control valves for controlling the flow of a working fluid supplied from a plurality of fluid pressure pumps to a plurality of actuators, and is supplied from the plurality of fluid pressure pumps. A first position in which the flow of the working fluid is in the first state, a second position in which the flow of the working fluid supplied from the plurality of fluid pressure pumps is in the second state, and supply from the plurality of fluid pressure pumps. It is equipped with an unload position that guides the working fluid to the tank and unloads multiple fluid pressure pumps, and a switching valve that switches the spool between them, when the switching valve is switched to the unload position. , The working fluid is not guided from the plurality of fluid pressure pumps to the plurality of actuators, and the plurality of actuator control valves can be switched by the pilot pressure of the pilot pump .

In the first invention, the pressure in the actuator can be reduced by switching the actuator control valve in a state where the switching valve is switched to the unload position during the dismantling work of the actuator.

The second invention further comprises a parallel passage connected to the fluid pressure pump and connected in parallel to a plurality of actuator control valves, and when the switching valve is switched to the unload position, the parallel passage is in a non-pressurized state. Will be done.

In the second invention, when the actuator control valve is switched so that the tank is connected to one of the actuators and the parallel passage is connected to the other while the switching valve is switched to the unload position, the other of the actuators is switched. It is not pressurized by the fluid pressure pump. As a result, the pressure in the actuator can be reduced even when the fluid pressure pump is being driven. After that, if the actuator control valve is set to the neutral position, the hydraulic oil is not supplied or discharged, so that the actuator can be removed. That is, the pressure inside the actuator can be reduced and the actuator can be removed while the fluid pressure pump is being driven.

In the third invention, the hydraulic pressure pump has a first pump for supplying the working fluid to the first circuit system and a second pump for supplying the working fluid to the second circuit system, and the actuator control valve has an actuator control valve. A plurality of first working control valves provided on the downstream side of the first traveling control valve and the first traveling control valve provided in the first circuit system, and a second traveling control valve provided in the second circuit system. It has a plurality of second working control valves provided on the downstream side of the second running control valve, and a parallel passage is connected to the first pump and the first running control valve and the first working control. A first parallel passage connected in parallel to the valve, a second parallel passage connected to the second pump and connected in parallel to the second traveling control valve and the second working control valve, In the first position, the working fluid of the first pump is guided to the first traveling control valve and the first working control valve, and the working fluid of the second pump is the second traveling control valve and the second. Guided by the working control valve, at the second position, the working fluid of the first pump is guided to the first running control valve and the second running control valve, and the working fluid of the second pump is controlled by the first working. Guided by the valve and the control valve for the second work, the spool has an annular groove provided on the outer peripheral surface and a hollow portion provided inside, and when the spool is in the unload position, the operation of the first pump is performed. The fluid is guided to the tank through the annular groove, and the working fluid of the second pump is guided to the tank through the hollow portion.

In the third invention, the traveling straightness of the vehicle body can be ensured by switching the switching valve to the second position, and the first pump and the second pump are unlocked by switching the switching valve to the unload position. By loading and switching the plurality of actuator control valves provided in the first circuit system and the second circuit system, the pressure in the plurality of actuators can be reduced.

A fourth aspect of the invention further comprises a valve body in which the spool is slidably accommodated, with a hollow portion extending in the axial direction of the spool to a first internal passage and from the first internal passage to the outer peripheral surface of the spool. It has a second internal passage extending from the valve body, and the opening of the second internal passage on the outer peripheral surface of the spool is covered with the inner peripheral surface of the valve body, so that the communication between the second pump and the tank is cut off. Will be done.

In the fifth aspect of the invention, the valve body has a tank port communicating with the tank, the spool has a land portion for blocking the tank port, and the opening of the second internal passage provided in the land portion is the valve body. By being covered by the inner peripheral surface of the tank, the communication between the second pump and the tank is cut off.

In the fourth and fifth inventions, it is possible to control the communication and disconnection between the second pump and the tank with a simple shape without increasing the shape of the spool and the valve body.

According to the present invention, it is possible to prevent the occurrence of oil leakage, oil splash, etc. during the dismantling work of the actuator without increasing the number of parts and the cost.

It is a circuit diagram which shows the hydraulic pressure control device which concerns on embodiment of this invention. It is sectional drawing which shows the cross section when the control valve for traveling straight travel is in a neutral position. It is sectional drawing which shows the cross section when the control valve for traveling straight travel is a traveling straight traveling position. It is sectional drawing which shows the cross section when the control valve for traveling straight travel is an unload position. It is a circuit diagram which shows the hydraulic pressure control device which concerns on the modification of embodiment of this invention.

The fluid pressure control device according to the embodiment of the present invention will be described with reference to the drawings.

The fluid pressure control device is applied to construction machinery such as a power shovel. The power shovels are an engine (not shown), a first pump 101 and a second pump 102 as hydraulic pressure pumps driven by the engine and discharging hydraulic oil as a working fluid, and a first pump 101 and a second pump 102. A fluid pressure control device that supplies and discharges hydraulic oil supplied from a hydraulic motor to a traveling motor and a turning motor, which are hydraulic motors, and a boom driving cylinder, an arm driving cylinder, a bucket driving cylinder, etc., which are hydraulic cylinders. The hydraulic pressure control device 100 and the tank T through which the hydraulic oil recirculates from the hydraulic pressure control device 100 are provided. Hydraulic motors and hydraulic cylinders are also collectively referred to as actuators.

The hydraulic control device 100 is connected to the first pump 101 to supply hydraulic oil discharged from the first pump 101 to the first circuit system HC1, and is connected to the second pump 102 to be discharged from the second pump 102. A second circuit system HC2 to which oil is supplied is provided. As will be described later, by switching the traveling straight-ahead control valve 25, the hydraulic oil discharged from the first pump 101 is also supplied to the second circuit system HC2 and discharged from the second pump 102. The oil is also supplied to the first circuit system HC1.

The first circuit system HC1 includes a first neutral passage 11 that guides hydraulic oil supplied from the first pump 101 to the tank T, a plurality of actuator control valves 12 connected in series to the first neutral passage 11, and a plurality of actuator control valves 12, which will be described later. A first parallel passage 13 branching from a first neutral passage 11 on the upstream side of the first traveling control valve 12A is provided. The first parallel passage 13 has an upstream side parallel passage 13a on the upstream side of the traveling straight-ahead control valve 25 and a downstream-side parallel passage 13b on the downstream side of the traveling straight-ahead control valve 25, which will be described later.

Each actuator control valve 12 is connected to the first neutral passage 11 by the first parallel passage 13. The first parallel passage 13 is connected to the first pump 101 via the first neutral passage 11 on the upstream side of the first traveling control valve 12A, and each actuator control valve 12, that is, the first traveling control valve 12A. And connected in parallel to the first working control valve (12B to 12E).

The plurality of actuator control valves 12 include a first traveling control valve 12A, a spare control valve 12B, a turning control valve 12C, a boom 2nd speed control valve 12D, and an arm 1st speed control valve 12E, and are upstream in this order. Placed from. The spare control valve 12B, the swivel control valve 12C, the boom 2-speed control valve 12D, and the arm 1-speed control valve 12E are first working control valves provided in the first circuit system HC1. That is, each first working control valve (12B, 12C, 12D, 12E) is provided on the downstream side of the first traveling control valve 12A.

The first traveling control valve 12A switches the supply and discharge of hydraulic oil to the traveling motor 111 provided on the right side of the vehicle body of the power shovel. The spare control valve 12B switches the supply and discharge of hydraulic oil to the hydraulic cylinder that drives the attachment such as a breaker or crusher, which is attached instead of the bucket described later. The turning control valve 12C switches the supply and discharge of hydraulic oil to the turning motor that turns the turning body arranged on the upper part of the vehicle body. The boom 2-speed control valve 12D switches the supply and discharge of hydraulic oil to the hydraulic cylinder that drives the boom. The arm 1-speed control valve 12E switches the supply and discharge of hydraulic oil to the hydraulic cylinder that drives the arm.

In this way, the plurality of actuator control valves 12 control the flow of hydraulic oil supplied from the first pump 101 or the second pump 102 to the plurality of actuators. A check valve 16 is provided on the upstream side of each actuator control valve 12 in the first parallel passage 13 to allow only hydraulic oil to flow from the first parallel passage 13 toward each actuator.

When all the actuator control valves 12 of the first circuit system HC1 are in the neutral position, the hydraulic oil discharged from the first pump 101 is guided to the tank T through the first neutral passage 11. When at least one actuator control valve 12 is switched to the operating position, the flow of hydraulic oil through the first neutral passage 11 to the tank T is blocked.

The first parallel passage 13 supplies the hydraulic oil supplied from the first pump 101 to the actuator control valve 12 when any of the actuator control valves 12 of the first circuit system HC1 is switched to the operating position.

On the other hand, the second circuit system HC2 includes a second neutral passage 21 that guides the hydraulic oil supplied from the second pump 102 to the tank T, and a plurality of actuator control valves 22 that are connected in series to the second neutral passage 21. It is connected to the neutral cut valve 24 connected to the second neutral passage 21 on the downstream side of the arm 2-speed control valve 22D, which will be described later, and to the second neutral passage 21 on the upstream side of the second traveling control valve 22A, which will be described later. A traveling straight-ahead control valve 25 as a switching valve and a second parallel passage 23 branching from a second neutral passage 21 on the upstream side of the traveling straight-ahead control valve 25 are provided. The second neutral passage 21 has an upstream neutral passage 21a on the upstream side of the traveling straight-ahead control valve 25 and a downstream-side neutral passage 21b on the downstream side of the traveling straight-ahead control valve 25.

Each actuator control valve 22 is connected to the second neutral passage 21 by a second parallel passage 23. The second parallel passage 23 is connected to the second pump 102 via the upstream neutral passage 21a, and each actuator control valve 22, that is, the second traveling control valve 22A and the second working control valve (22B to 22D). ) Is connected in parallel.

The plurality of actuator control valves 22 are composed of a second traveling control valve 22A, a bucket control valve 22B, a boom 1st speed control valve 22C, and an arm 2nd speed control valve 22D, and are arranged from the upstream in this order. The bucket control valve 22B, the boom 1-speed control valve 22C, and the arm 2-speed control valve 22D are second working control valves provided in the second circuit system HC2. That is, each of the second working control valves (22B to 22D) is provided on the downstream side of the second traveling control valve 22A.

The second traveling control valve 22A switches the supply and discharge of hydraulic oil to the traveling motor 112 provided on the left side of the vehicle body of the power shovel. The bucket control valve 22B switches the supply and discharge of hydraulic oil to the hydraulic cylinder 113 that drives the bucket. The boom 1-speed control valve 22C switches the supply and discharge of hydraulic oil to the hydraulic cylinder that drives the boom. The arm 2-speed control valve 22D switches the supply and discharge of hydraulic oil to the hydraulic cylinder that drives the arm.

In this way, the plurality of actuator control valves 22 control the flow of hydraulic oil supplied from the first pump 101 or the second pump 102 to the plurality of actuators. On the upstream side of each actuator control valve 22 in the second parallel passage 23, a check valve 26 that only allows hydraulic oil to flow from the second parallel passage 23 toward each actuator is provided.

When all the actuator control valves 22 of the second circuit system HC2 are in the neutral position, the hydraulic oil discharged from the second pump 102 is guided to the tank T through the second neutral passage 21. When at least one actuator control valve 22 is switched to the operating position, the flow of hydraulic oil to the tank T through the second neutral passage 21 is blocked.

The second parallel passage 23 supplies the hydraulic oil supplied from the second pump 102 to the actuator control valve 22 when any of the actuator control valves 22 of the second circuit system HC2 is switched to the operating position.

The neutral cut valve 24 opens the second neutral passage 21 when it is in the normal position, and closes the second neutral passage 21 when it is switched to the closed position. In the hydraulic control device 100 according to the present embodiment, the hydraulic oil of the second pump 102 is supplied to another control valve (not shown) through the branch passage 28 branching from the second neutral passage 21 upstream of the neutral cut valve 24. It is configured to be able to lead to.

The traveling straight-ahead control valve 25 is provided in the second neutral passage 21 and the first parallel passage 13 on the upstream side of the actuator control valves 12 and 22. In other words, the traveling straight-ahead control valve 25 is located between the upstream side parallel passage 13a and the downstream side parallel passage 13b of the first parallel passage 13, and is located on the upstream side neutral passage 21a and the downstream side of the second neutral passage 21. It is interposed between the neutral passage 21b and the neutral passage 21b. The traveling straight-ahead control valve 25 is a switching valve that can be switched to three positions.

The traveling straight-ahead control valve 25 has a neutral position A (see FIG. 2) as a first position in which the flow of hydraulic oil supplied from the first pump 101 and the second pump 102 is set as the first state, and a first. A traveling straight position B (see FIG. 3) as a second position in which the flow of hydraulic oil supplied from the pump 101 and the second pump 102 is set to a second state different from the first state, and the first pump 101. And the spool 40 (see FIGS. 2 to 4) between the unload position C for guiding the hydraulic oil supplied from the second pump 102 to the tank T and unloading the first pump 101 and the second pump 102. Can be switched.

The switching positions (A, B, C) of the traveling straight-ahead control valve 25 change according to the pilot pressure acting on the pilot chambers 25a and 25b provided at both ends of the traveling straight-ahead control valve 25. When the pilot pressure does not act on any of the pilot chambers 25a and 25b, the spring 25c causes the traveling straight-ahead control valve 25 to be in the neutral position A.

At the neutral position A, the upstream side parallel passage 13a is connected to the downstream side parallel passage 13b, and the upstream side neutral passage 21a is connected to the downstream side neutral passage 21b. The second parallel passage 23 is connected to the upstream neutral passage 21a. Therefore, in the neutral position A, the hydraulic oil discharged from the first pump 101 is guided to each actuator control valve 12 of the first circuit system HC1, and the hydraulic oil discharged from the second pump 102 is the second circuit. It is guided to each actuator control valve 22 of the system HC2.

At the traveling straight position B, the upstream side parallel passage 13a is connected to the downstream side neutral passage 21b, and the upstream side neutral passage 21a is connected to the downstream side parallel passage 13b. Therefore, at the traveling straight position B, the hydraulic oil discharged from the first pump 101 is guided to the first traveling control valve 12A of the first circuit system HC1 and the second traveling control valve 22A of the second circuit system HC2. At the same time, the hydraulic oil discharged from the second pump 102 is sent to the first working control valve (12B to 12E) of the first circuit system HC1 and the second working control valve (22B to 22D) of the second circuit system HC2. Be guided.

When the power shovel is traveling without driving the excavation part including the boom, arm, bucket, etc., or when the excavator is being driven without driving, the first pilot chamber 25a and The second pilot chamber 25b has a tank pressure, and the traveling straight-ahead control valve 25 is maintained at the neutral position A. On the other hand, when the actuator of the excavation section is driven while the traveling motors 111 and 112 are being driven, the pilot pressure acts on the first pilot chamber 25a, and the traveling straight-ahead control valve 25 is switched to the traveling straight-ahead position B. .. As a result, the circuit for traveling and the circuit other than traveling become independent, so that the traveling straightness of the vehicle body is ensured.

At the unload position C, the upstream side parallel passage 13a is connected to the tank passage 29. The tank passage 29 is connected to a tank T for storing hydraulic oil. That is, at the unload position C, the hydraulic oil in the upstream parallel passage 13a is guided to the tank T, and the first pump 101 is unloaded. Further, at the unload position C, the communication between the first pump 101 and the actuator control valves (12B to 12E) of the first circuit system HC1 through the first parallel passage 13 is cut off.

Further, at the unload position C, the upstream neutral passage 21a is connected to the tank passage 29. That is, at the unload position C, the hydraulic oil in the upstream neutral passage 21a is guided to the tank T, and the second pump 102 is unloaded. Further, at the unload position C, the hydraulic oil of the second parallel passage 23 branching from the upstream neutral passage 21a is guided to the tank T.

The power shovel has a controller 108 that controls the operation of each part of the power shovel, an actuator operating device (not shown) for switching the actuator control valves 12 and 22, and a running straight control valve 25 at the unload position C. An unload operation device 107 for switching is provided. The actuator operating device and the unload operating device 107 are provided in the cab of the power shovel.

The unload operation device 107 has an operation unit 107b such as a switch and a lever, and the operation state is detected by the operation detection unit 107a. The operation detection unit 107a is connected to the controller 108 and outputs a detection signal to the controller 108. When the unload operation device 107 is operated to the unload position, the controller 108 outputs an on signal (excitation current) to the solenoid of the electromagnetic proportional valve 109 based on the detection signal from the operation detection unit 107a. As a result, the hydraulic oil of the pilot hydraulic source 105 is depressurized to generate a pilot pressure, and this pilot pressure acts on the second pilot chamber 25b of the traveling straight-ahead control valve 25.

When the pilot pressure acts on the second pilot chamber 25b, the traveling straight-ahead control valve 25 switches to the unload position C, and the first pump 101 and the second pump 102 are unloading. Further, since the communication between the first pump 101 and the second pump 102 and the downstream side parallel passage 13b is cut off, the downstream side parallel passage 13b of the first parallel passage 13 is positively operated by the first pump 101 and the second pump 102. It becomes a non-pressurized state without being pressurized. Further, since the second parallel passage 23 communicates with the tank T, the second parallel passage 23 is in a non-pressurized state in which it is not positively pressurized by the second pump 102.

At this time, the drive of the first pump 101 and the second pump 102 is maintained, and the drive of the pilot pump (not shown) driven by the engine is also maintained. The hydraulic oil discharged from the pilot pump is depressurized according to the operation amount of the actuator operating device (not shown), and the pilot chamber of the actuator control valves 12 and 22 is used as the pilot pressure for switching the actuator control valves 12 and 22. Is entered in. That is, in the present embodiment, when the traveling straight-ahead control valve 25 is switched to the unload position C, the plurality of actuator control valves 12 and 22 can be switched.

The structure of the traveling straight-ahead control valve 25 will be described with reference to FIGS. 2 to 4. FIG. 2 is a cross-sectional view showing a cross section when the traveling straight-ahead control valve 25 is in the neutral position A. FIG. 3 is a cross-sectional view showing a cross section when the traveling straight-ahead control valve 25 is in the traveling straight-ahead position B. FIG. 4 is a cross-sectional view showing a cross section when the traveling straight-ahead control valve 25 is at the unload position C.

As shown in FIG. 2, the traveling straight-ahead control valve 25 is inserted into a valve body 30 having a hole 30a having a circular cross section and a hole 30a, and is inserted in the central axial direction of the spool 40 (hereinafter, also simply referred to as an axial direction). ) Silvers a slidable columnar spool 40. That is, the spool 40 is slidably housed in the valve body 30. In the following description, one end side of the valve body 30 refers to the left end side in FIG. 2, and the other end side of the valve body 30 refers to the right end side in FIG.

On the inner peripheral surface of the hole 30a of the valve body 30, the tank port 35 communicating with the tank T through the tank passage 29, the first inlet port 31 communicating with the upstream parallel passage 13a, and the downstream neutral passage 21b communicate with each other. A second outlet port 34, a second inlet port 32 communicating with the upstream neutral passage 21a, and a first exit port 33 communicating with the downstream parallel passage 13b are provided in this order from one end side to the other end side. Be done. Further, on the inner peripheral surface of the hole 30a of the valve body 30, an annular recess 37 is provided between the tank port 35 and the first inlet port 31, and an annular recess 38 is provided on the other end side of the first outlet port 33. Be done. The annular recess 37 and the annular recess 38 communicate with each other by a passage 36 provided in the valve body 30.

The spool 40 has a first land portion 51, a second land portion 52, a third land portion 53, and a fourth land portion 54 as land portions sliding on the inner peripheral surface of the hole 30a, from one end side to the other end side. It is provided in this order toward. The first land portion 51 is provided so as to be able to shut off the tank port 35. The second land portion 52 is provided so that the communication between the first inlet port 31 and the second outlet port 34 can be cut off, and the communication between the second exit port 34 and the second inlet port 32 can be cut off. The third land portion 53 is provided so as to be able to block the communication between the second inlet port 32 and the first outlet port 33 and to block the communication between the first outlet port 33 and the annular recess 38.

On the outer peripheral surface of the spool 40, a first annular groove 61, a second annular groove 62, and a third annular groove 63 as annular grooves are provided in this order from one end side to the other end side. The first annular groove 61 is provided between the first land portion 51 and the second land portion 52, the second annular groove 62 is provided between the second land portion 52 and the third land portion 53, and the third annular groove 62 is provided. The annular groove 63 is provided between the third land portion 53 and the fourth land portion 54.

A hollow portion 41 is provided inside the spool 40. The hollow portion 41 serves as an axial passage 42 as a first internal passage extending in the axial direction of the spool 40 and a pair of second internal passages extending from the axial passage 42 to the outer peripheral surface of the spool 40. It has radial passages 43 and 44.

The axial passage 42 is formed by drilling or the like from the other end surface of the spool 40 facing the second pilot chamber 25b. The opening on the other end side of the spool 40 is closed by the plug 49.

The radial passage 43 extends radially from the axial passage 42 to the spool 40 and opens to the bottom surface of the second annular groove 62. The radial passage 44 extends in the radial direction of the spool 40 from the axial passage 42 and opens to the outer peripheral surface of the first land portion 51.

At one end of the valve body 30, a spring 25c for urging the spool 40 in the axial direction and a first pilot chamber 25a for guiding the pilot pressure for urging the spool 40 to the other end side are provided. At the other end of the valve body 30, a second pilot chamber 25b is provided to which the pilot pressure for urging the spool 40 to one end side is guided.

When the pilot pressure is not guided to either the first pilot chamber 25a or the second pilot chamber 25b, the spool 40 is held in the neutral position A shown in FIG. When the pilot pressure is supplied to the first pilot chamber 25a, the spool 40 slides to the other end side against the urging force of the spring 25c and is held at the traveling straight position B shown in FIG. When the pilot pressure is supplied to the second pilot chamber 25b, the spool 40 slides to one end side against the urging force of the spring 25c and is held at the unload position C shown in FIG.

As shown in FIG. 2, when the pilot pressure is not supplied to either the first pilot chamber 25a and the second pilot chamber 25b, the spool 40 is held in the neutral position A. At this time, the hydraulic oil guided from the upstream side parallel passage 13a passes through the first inlet port 31, the first annular groove 61, the annular recess 37, the passage 36, the annular recess 38, the third annular groove 63, and the first outlet port 33. It is guided to the downstream side parallel passage 13b. Further, the hydraulic oil guided from the upstream neutral passage 21a is guided to the downstream neutral passage 21b through the second inlet port 32, the second annular groove 62, and the second outlet port 34. When the spool 40 is held in the neutral position A, the opening of the radial passage 44 on the outer peripheral surface of the spool 40 is covered with the inner peripheral surface of the valve body 30. As a result, the communication between the tank port 35 and the second inlet port 32 and the second outlet port 34 through the hollow portion 41 is cut off. That is, the communication between the second pump 102 and the tank T is cut off.

As shown in FIG. 3, when the pilot pressure is supplied to the first pilot chamber 25a, the spool 40 is switched to the traveling straight traveling position B. As a result, the hydraulic oil guided from the upstream side parallel passage 13a is guided to the downstream side neutral passage 21b through the first inlet port 31, the first annular groove 61, and the second outlet port 34. Further, the hydraulic oil guided from the upstream neutral passage 21a is guided to the downstream parallel passage 13b through the second inlet port 32, the second annular groove 62, and the first outlet port 33. The opening of the radial passage 44 on the outer peripheral surface of the spool 40 is covered with the inner peripheral surface of the valve body 30. As a result, the communication between the tank port 35 and the second inlet port 32 and the first outlet port 33 through the hollow portion 41 is cut off. That is, the communication between the second pump 102 and the tank T is cut off.

As shown in FIG. 4, when the pilot pressure is supplied to the second pilot chamber 25b, the spool 40 is switched to the unload position C. As a result, the hydraulic oil of the first pump 101 guided from the upstream side parallel passage 13a is guided to the tank passage 29 through the first inlet port 31, the first annular groove 61, and the tank port 35, and to the tank T through the tank passage 29. Be guided. Further, the hydraulic oil of the second pump 102 guided from the upstream neutral passage 21a is guided to the tank passage 29 through the second inlet port 32, the second annular groove 62, the hollow portion 41, and the tank port 35, and is guided to the tank passage 29 through the tank passage 29. Guided to tank T. That is, the hydraulic oil guided from the upstream side parallel passage 13a and the hydraulic oil guided from the upstream side neutral passage 21a merge in the traveling straight-ahead control valve 25 and are guided to the tank passage 29.

When the spool 40 is switched to the unload position C, the communication between the first inlet port 31 and the second exit port 34 is cut off by the second land portion 52, and the second inlet port 32 and the first exit port 33 are disconnected from each other. Communication is blocked by the third land portion 53. Further, the communication between the first outlet port 33 and the annular recess 38 is blocked by the fourth land portion 54.

Here, instead of the hollow portion 41, the axial length of the second annular groove 62 may be lengthened to connect the second pump 102 to the tank T. In this case, when the spool 40 is switched to the unload position C, all of the second inlet port 32, the second outlet port 34, the first inlet port 31, and the tank port 35 communicate with each other through the second annular groove 62. do. As a result, both the first pump 101 and the second pump 102 can be unloaded. However, in this case, it is necessary to adjust the dimensions so that the second inlet port 32 and the second outlet port 34 do not communicate with each other when the spool 40 is switched to the traveling straight position B, and the valve body 30 needs to be adjusted. It may lead to an increase in size.

On the other hand, in the present embodiment, the hollow portion 41 through which the hydraulic oil flows is provided inside the spool 40, and the opening of the radial passage 44 of the hollow portion 41 is covered with the inner peripheral surface of the valve body 30. , The communication between the second pump 102 and the tank T was cut off. Therefore, it is possible to control the communication and disconnection between the second pump 102 and the tank T with a simple shape without increasing the shape of the spool 40 and the valve body 30.

The actuator dismantling work will be described with reference to FIG. As an example of the dismantling work, the work of removing the hydraulic cylinder 113 for driving the bucket, which is the actuator of the second circuit system HC2, from the power shovel will be described.

When the operation unit 107b of the unload operation device 107 is operated to the unload position, the controller 108 performs a process of unloading the first pump 101 and the second pump 102 based on the detection signal detected by the operation detection unit 107a. Execute the dismantling work preparation mode including. When the dismantling work preparation mode is executed, for example, the controller 108 reduces the rotation speed of the engine to a predetermined rotation speed and reduces the push-out capacity of the first pump 101 and the second pump 102 to the minimum value. Further, the controller 108 outputs an ON signal to the electromagnetic proportional valve 109 to apply a predetermined pilot pressure to the second pilot chamber 25b of the traveling straight-ahead control valve 25.

When a predetermined pilot pressure is supplied to the second pilot chamber 25b of the traveling straight-ahead control valve 25, the traveling straight-ahead control valve 25 switches from the neutral position A to the unload position C. At this time, the engine is maintained in a driven state. That is, in this state, the pilot pump driven by the engine can be used as a pilot hydraulic pressure source, and the pilot pressure (secondary pressure) corresponding to the operation amount of the actuator operating device can be applied to the pilot chambers of the actuator control valves 12 and 22. .. That is, when the traveling straight-ahead control valve 25 is switched to the unload position C, the plurality of actuator control valves 12 and 22 can be switched.

Therefore, when the operation lever of the actuator operating device for the bucket is operated from the neutral position by a predetermined operating amount, the bucket control valve 22B is switched from the neutral position to the predetermined operating position.

When the operation lever for the bucket is operated to the cylinder extension side, the bucket control valve 22B is switched to the extension operation position, the bottom side chamber 113b of the hydraulic cylinder 113 is connected to the second parallel passage 23, and the rod side chamber 113r is the tank passage. Connected to 29.

The second parallel passage 23 communicates with the tank passage 29 through the upstream neutral passage 21a and the traveling straight-ahead control valve 25. Therefore, the second parallel passage 23 is in a non-pressurized state in which it is not positively pressurized by the second pump 102. Since the second parallel passage 23 communicates with the tank T, it is possible to prevent the hydraulic oil from being supplied to the bottom side chamber 113b. That is, the bottom side chamber 113b is prevented from being pressurized. Since the check valve 26 is provided on the upstream side of the bucket control valve 22B in the second parallel passage 23, hydraulic oil is not guided from the bottom side chamber 113b to the tank T through the second parallel passage 23.

That is, the rod side chamber 113r is in a state where the hydraulic oil can be discharged to the tank T through the tank passage 29, and the bottom side chamber 113b is in a state where the hydraulic oil is not supplied or discharged. As a result, in the hydraulic cylinder 113, the pressure of the rod side chamber 113r drops to the tank pressure without the bottom side chamber 113b being pressurized.

Here, if the pressure in the bottom side chamber 113b is low and there is no concern that oil leakage or the like will occur, the bucket control valve 22B is returned to the neutral position. If the bucket control valve 22B is set to the neutral position, the hydraulic oil is not supplied or discharged, so that the hydraulic cylinder 113 can be removed. If the pressure in the bottom side chamber 113b is high and there is a concern that oil leakage or the like may occur, the operation lever for the bucket is operated to the cylinder contraction side to switch the bucket control valve 22B to the contraction operation position. As a result, the rod side chamber 113r of the hydraulic cylinder 113 is connected to the second parallel passage 23, and the bottom side chamber 113b is connected to the tank passage 29. By connecting the bottom side chamber 113b of the hydraulic cylinder 113 to the tank passage 29, the bottom side chamber 113b drops to the tank pressure. Although the rod side chamber 113r is connected to the second parallel passage 23, since the second parallel passage 23 communicates with the tank T, it is prevented that hydraulic oil is supplied to the rod side chamber 113r. That is, the rod side chamber 113r is prevented from being pressurized. After that, the bucket control valve 22B is returned to the neutral position, and the hydraulic cylinder 113 is removed from the power shovel. Since the hydraulic cylinder 113 is removed from the power shovel after the pressure in the hydraulic cylinder 113 is reduced, it is possible to prevent oil leakage, oil splash, and the like during the dismantling work.

When the traveling straight-ahead control valve 25 is switched to the unload position C and the second parallel passage 23 communicates with the tank T, the second parallel passage 23 is not positively pressurized by the second pump 102. It suffices if it is in a non-pressurized state. That is, the pressure in the second parallel passage 23 may be higher than the tank pressure due to the pressure loss of the hydraulic oil passing through the traveling straight-ahead control valve 25. In this case, each pipe and the running straight control valve 25 may be configured so that the pressure in the second parallel passage 23 is such that the check valve 26 on the upstream side of each actuator control valve 22 is not opened. preferable.

As described above, in the present embodiment, in the dismantling work, one pressure chamber of the hydraulic cylinder 113 is connected to the tank T in a state where the traveling straight-ahead control valve 25 is switched to the unload position C, and the other pressure chamber is connected. Is switched to the bucket control valve 22B so as to be connected to the second parallel passage 23. As a result, even when the first and second pumps 101 and 102 are being driven, one pressure chamber can be depressurized without pressurizing the other pressure chamber of the hydraulic cylinder 113.

As another example of the dismantling work, the work of removing the hydraulic cylinder for driving the arm from the power shovel will be described. Since the procedure of the dismantling work and the switching operation of the running straight control valve 25 are the same, only the points different from the dismantling work of the hydraulic cylinder 113 for driving the bucket will be described.

When the traveling straight-ahead control valve 25 is switched to the unload position C, the communication between the first pump 101 and the second pump 102 and the actuator control valve (12B to 12E) through the first parallel passage 13 is cut off. That is, the downstream side parallel passage 13b of the first parallel passage 13 is in a non-pressurized state in which the first pump 101 and the second pump 102 do not positively pressurize.

By switching the arm 1-speed control valve 12E in this state, the pressure chamber of one of the hydraulic cylinders for driving the arm can be depressurized without pressurizing the pressure chamber of the other.

In this embodiment, when the first and second traveling control valves 12A and 22A are in the neutral position, the inlet and outlet of the traveling motors 111 and 112 communicate with the tank T, so that the pressure of the traveling motors 111 and 112 is reduced. The work can be omitted.

As described above, in the present embodiment, the traveling straight-ahead control valve 25 is switched to the unload position C, and the first and second pumps 101 and 102 are in the unload state, so that the engine is not stopped and the actuator is inside the actuator. The pressure can be reduced and the actuator can be removed. Since a plurality of actuators can be removed at the same time while the engine and each pump (first and second pumps 101, 102, pilot pump) are being driven, the work efficiency of the dismantling work can be improved.

According to the above-described embodiment, the following effects are exhibited.

The hydraulic control device 100 includes a traveling straight-ahead control valve 25 in which the spool 40 is switched between the neutral position A, the traveling straight-ahead position B, and the unloading position C, and the traveling straight-ahead control valve 25 is in the unloading position. When switched to C, the plurality of actuator control valves 12 and 22 can be switched. As a result, during the dismantling work of the actuator, the actuator control valves 12 and 22 are switched in the state where the traveling straight control valve 25 is switched to the unload position C, and the actuator is communicated with the tank, whereby the pressure in the actuator is reached. Can be reduced. As described above, in the present embodiment, the unload position C is provided in the traveling straight-ahead control valve 25 that is switched between the neutral position A and the traveling straight-ahead position B. That is, the traveling straight-ahead control valve 25 has an unloading function in addition to a function of ensuring traveling straightness when the excavated portion operates during traveling. This makes it possible to reduce the pressure of the actuator without newly providing accessories such as a dedicated pressure relief device. That is, according to the present embodiment, it is possible to reduce the pressure in the actuator without increasing the number of parts and the cost, and it is possible to prevent the occurrence of oil leakage, oil splash, etc. during the dismantling work of the actuator. can.

The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the above-described embodiment, or to combine the configurations described in the following different modifications. Is.

<Modification 1>
In the above embodiment, an example in which the traveling straight-ahead control valve 25 has an unload position C has been described, but the present invention is not limited thereto. For example, as shown in FIG. 5, the neutral cut valve 224 may have an unload position C2. In the hydraulic control device 200 according to this modification, the neutral cut valve 224 is a switching valve that can be switched to three positions: a normal position A2 as a first position, a closed position B2 as a second position, and an unload position C2. Is.

At the normal position A2, the second neutral passage 21 on the downstream side of the arm 2nd speed control valve 22D is opened, and when all the actuator control valves 22 of the second circuit system HC2 are in the neutral position, they are supplied from the second pump 102. The hydraulic oil to be generated is in the first state of being guided to the tank T. At the closed position B2, the second neutral passage 21 is closed, and another control valve (not shown) is passed through a branch passage 28 branching from the second neutral passage 21 between the arm 2nd speed control valve 22D and the neutral cut valve 224. ), The hydraulic oil of the second pump 102 is guided to the second state.

At the unload position C2, the first parallel passage 13 and the second parallel passage 23 are connected to the tank passage 29, and the second neutral passage 21 is opened. At the normal position A2 and the closed position B2, the communication between the first parallel passage 13 and the second parallel passage 23 and the tank passage 29 is cut off.

Therefore, when the neutral cut valve 224 is switched to the unload position C2, the hydraulic oil in the first parallel passage 13 and the second parallel passage 23 is guided to the tank T, and the first parallel passage 13 and the second parallel passage 23 are not added. It becomes a pressure state. In this state, the pressure in each actuator can be reduced by switching the first working control valve (12B to 12E) and the second working control valve (22B to 22D) from the neutral position to the operating position. Further, by returning the first working control valve (12B to 12E) and the second working control valve (22B to 22D) to the neutral position, each actuator can be removed from the power shovel. That is, as in the above embodiment, the pressure in each actuator can be reduced and each actuator can be removed while the engine and each pump (first and second pumps 101, 102, pilot pump) are being driven.

<Modification 2>
In the above embodiment, the hydraulic control device 100 including the first circuit system HC1 and the second circuit system HC2 has been described as an example, but the present invention is not limited thereto. The circuit system may be one or three or more.

<Modification 3>
In the above embodiment, the opening of the radial passage 44 provided in the first land portion 51 is covered with the inner peripheral surface of the valve body 30, so that the communication between the second pump 102 and the tank T is cut off. However, the present invention is not limited to this. For example, the second pump 102 and the tank T are provided by providing the radial passage 43 in the second land portion 52 and covering the opening of the radial passage 43 of the second land portion 52 with the inner peripheral surface of the valve body 30. Communication may be cut off.

<Modification example 4>
In the above embodiment, when the first and second traveling control valves 12A and 22A are in the neutral position, the entrances and exits of the traveling motors 111 and 112 communicate with the tank T. Therefore, when disassembling the traveling motors 111 and 112 from the power shovel, it is not necessary to reduce the pressure of the traveling motors 111 and 112. On the other hand, when the first and second traveling control valves 12A and 22A are in the neutral position, when the communication between the inlet / outlet of the traveling motor 111 and the tank T is cut off, the pressure of the traveling motors 111 and 112 is also reduced. Work is required.

In this case, after switching the traveling straight-ahead control valve 25 to the unload position C, the first and second traveling control valves 12A and 22A and the first and second working control valves (12B to 12E, 22B to 22D). At the same time, a predetermined pilot pressure is also guided to the first pilot chamber 25a. That is, the pilot pressure is guided to both the first pilot chamber 25a and the second pilot chamber 25b of the traveling straight-ahead control valve 25. Therefore, it is preferable to configure the unload position C so that the unload position C is maintained even when the pilot pressure is guided to the first pilot chamber 25a.

For example, the pilot pressure acting on the second pilot chamber 25b is made larger than the pilot pressure acting on the first pilot chamber 25a. Alternatively, the pressure receiving area of the spool 40 with respect to the pilot pressure guided to the second pilot chamber 25b is made larger than the pressure receiving area of the spool 40 with respect to the pilot pressure guided to the first pilot chamber 25a. In this way, when the operation unit 107b of the unload operation device 107 is operated to the unload position, the traveling straight-ahead control valve 25 is preferentially switched to the unloading position C, thereby causing the traveling motor. And the pressure in each actuator including the hydraulic cylinder can be reduced simultaneously.

The configuration, operation, and effect of the embodiment of the present invention configured as described above will be collectively described.

The hydraulic control devices 100 and 200 as the fluid pressure control device include a plurality of actuators that control the flow of hydraulic oil as a working fluid supplied from the fluid pressure pumps (first pump 101 and second pump 102) to the plurality of actuators. The control valves 12 and 22 and the first position (neutral position A, normal position A2) in which the flow of the hydraulic fluid supplied from the fluid pressure pumps (first pump 101, second pump 102) is set to the first state. , A second position (running straight position B, blockage position B2) in which the flow of hydraulic fluid supplied from the fluid pressure pumps (first pump 101, second pump 102) is set to a second state different from the first state. ) And the unload position C for guiding the hydraulic oil supplied from the fluid pressure pumps (first pump 101, second pump 102) to the tank T and unloading the fluid pressure pumps (first pump 101, second pump 102). A switching valve (running straight control valve 25, neutral cut valve 224) for switching the spool 40 between C2 and C2 is provided, and the switching valve (running straight control valve 25, neutral cut valve 224) is unloaded. When the positions C and C2 are switched, the plurality of actuator control valves 12 and 22 can be switched.

In this configuration, when the actuator is disassembled, the actuator control valves 12 and 22 are switched while the switching valves (running straight control valve 25, neutral cut valve 224) are switched to the unload positions C and C2. , The pressure in the actuator can be reduced. A switching valve (running straight control valve 25, neutral) having a predetermined function of being switched between a first position (neutral position A, normal position A2) and a second position (running straight position B, closed position B2). The cut valve 224) is provided with an unload position C to have an unload function. This makes it possible to reduce the pressure of the actuator without newly providing accessories such as a dedicated pressure relief device. Therefore, the pressure in the actuator can be reduced without increasing the number of parts and the cost, and oil leakage, oil splash, and the like can be prevented during the dismantling work of the actuator.

The hydraulic control devices 100 and 200 are connected to the fluid pressure pumps (first pump 101 and second pump 102) and are connected in parallel to the plurality of actuator control valves 12 and 22 (first parallel passage 13, 1st parallel passage 13,). A second parallel passage 23) is further provided, and when the switching valve (running straight control valve 25, neutral cut valve 224) is switched to the unload positions C and C2, the parallel passage (first parallel passage 13, second parallel passage 13) is provided. 23) is in a non-pressurized state.

In this configuration, with the switching valve (running straight control valve 25, neutral cut valve 224) switched to the unload positions C and C2, one pressure chamber (for example, a rod) of the actuator (for example, the hydraulic cylinder 113) is switched. The actuator control valves 12 and 22 are switched so as to connect the tank T to the side chamber 113r) and connect the parallel passages (first parallel passage 13, second parallel passage 23) to the other pressure chamber (for example, the bottom side chamber 113b). At this time, the other pressure chamber of the actuator (for example, the bottom side chamber 113b) is not pressurized by the fluid pressure pumps (first pump 101, second pump 102). As a result, the pressure in the actuator can be reduced even when the fluid pressure pumps (first pump 101 and second pump 102) are being driven. After that, if the actuator control valves 12 and 22 are set to the neutral position, the hydraulic oil is not supplied or discharged, so that the actuator can be removed. That is, the pressure in the actuator can be reduced and the actuator can be removed while the fluid pressure pumps (first pump 101 and second pump 102) are being driven.

In the hydraulic control device 100, the fluid pressure pumps (first pump 101, second pump 102) supply the hydraulic oil to the first pump 101 and the second circuit system HC2 for supplying the hydraulic oil to the first circuit system HC1. It has a second pump 102, and an actuator control valve is provided on the downstream side of the first traveling control valve 12A and the first traveling control valve 12A provided in the first circuit system HC1 for a plurality of first operations. The control valves (12B to 12E) and a plurality of second working control valves (22B to 22D) provided on the downstream side of the second traveling control valve 22A and the second traveling control valve 22A provided in the second circuit system HC2. ), And the parallel passages (first parallel passage 13, second parallel passage 23) are connected to the first pump 101, and the first traveling control valve 12A and the first working control valve (12B to The first parallel passage 13 connected in parallel to 12E) and the second traveling control valve 22A and the second working control valve (22B to 22D) connected in parallel to the second pump 102. It has a second parallel passage 23 to be connected, and in the first position (neutral position A), the hydraulic oil of the first pump 101 is the first traveling control valve 12A and the first working control valve (12B to 12E) and the hydraulic oil of the second pump 102 are guided to the second traveling control valve 22A and the second working control valve (22B to 22D), and at the second position (traveling straight position B), the second position is reached. The hydraulic oil of the 1 pump 101 is guided to the first traveling control valve 12A and the second traveling control valve 22A, and the hydraulic oil of the second pump 102 is used for the first working control valve (12B to 12E) and the second working. Guided by the control valves (22B to 22D), the spool 40 has an annular groove (first annular groove 61) provided on the outer peripheral surface and a hollow portion 41 provided inside, and the spool 40 is in the unload position. When in C, the hydraulic oil of the first pump 101 is guided to the tank T through the annular groove (first annular groove 61), and the hydraulic oil of the second pump 102 is guided to the tank T through the hollow portion 41.

In this configuration, by switching the traveling straight-ahead control valve 25 as a switching valve to the traveling straight-ahead position B, which is the second position, the traveling straightness of the vehicle body can be ensured, and the traveling straight-ahead control valve 25 is released. By switching to the load position C, the first pump 101 and the second pump 102 are unloaded, and by switching the plurality of actuator control valves 12 and 22 provided in the first circuit system HC1 and the second circuit system HC2, a plurality of actuator control valves 12 and 22 are switched. The pressure in the actuator can be reduced.

The hydraulic control device 100 further includes a valve body 30 in which the spool 40 is slidably accommodated, and the hollow portion 41 has an axial passage 42 as a first internal passage extending in the axial direction of the spool 40 and a shaft. It has radial passages 43, 44 as a second internal passage extending from the directional passage 42 to the outer peripheral surface of the spool 40, and the opening of the radial passages 43, 44 on the outer peripheral surface of the spool 40 is formed. By being covered by the inner peripheral surface of the valve body 30, the communication between the second pump 102 and the tank T is cut off.

In the hydraulic control device 100, the valve body 30 has a tank port 35 communicating with the tank T, and the spool 40 has a land portion (first land portion 51) for blocking the tank port 35, and the land portion (first land portion 51). The opening of the radial passage 44 provided in the land portion 51) is covered with the inner peripheral surface of the valve body 30, so that the communication between the second pump 102 and the tank T is cut off.

In these configurations, the shapes of the spool 40 and the valve body 30 do not become large, and the communication and disconnection between the second pump 102 and the tank T can be controlled with a simple shape.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. do not have.

11 ... 1st neutral passage, 12 ... Actuator control valve, 12A ... 1st traveling control valve (actuator control valve), 12B ... Spare control valve (1st work control valve, actuator) Control valve), 12C ... Swing control valve (1st work control valve, actuator control valve), 12D ... Boom 2nd speed control valve (1st work control valve, actuator control valve), 12E.・ ・ Arm 1st speed control valve (1st work control valve, actuator control valve), 13 ... 1st parallel passage (parallel passage), 21 ... 2nd neutral passage, 22 ... Actuator control valve , 22A ... 2nd running control valve (actuator control valve), 22B ... bucket control valve (2nd work control valve, actuator control valve), 22C ... boom 1st speed control valve (1st) 2 work control valve, actuator control valve), 22D ... arm 2nd speed control valve (2nd work control valve, actuator control valve), 23 ... 2nd parallel passage (parallel passage), 25 ...・ Control valve for traveling straight (switching valve), 30 ... valve body, 35 ... tank port, 40 ... spool, 41 ... hollow part, 42 ... axial passage (first internal passage) ), 43 ... radial passage (second internal passage), 44 ... radial passage (second internal passage), 51 ... first land portion (land portion), 61 ... first ring Groove (annular groove), 100 ... Hydraulic control device (fluid pressure control device), 101 ... 1st pump (fluid pressure pump), 102 ... 2nd pump (fluid pressure pump), 111, 112. ... Travel motor (actuator), 113 ... Hydraulic cylinder (actuator), 200 ... Hydraulic control device (fluid pressure control device), 224 ... Neutral cut valve (switching valve), A ... Neutral Position (first position), A2 ... normal position (first position), B ... traveling straight position (second position), B2 ... closed position (second position), C, C2 ... Unload position, HC1 ... 1st circuit system, HC2 ... 2nd circuit system, T ... Tank

Claims (5)

Multiple actuator control valves that control the flow of working fluid supplied from multiple fluid pressure pumps to multiple actuators,
The first position where the flow of the working fluid supplied from the plurality of fluid pressure pumps is the first state and the flow of the working fluid supplied from the plurality of fluid pressure pumps are different from the first state. The spool is switched between the second position in which the second state is set and the unload position in which the working fluid supplied from the plurality of fluid pressure pumps is guided to the tank and the plurality of fluid pressure pumps are unloaded. Equipped with a switching valve,
When the switching valve is switched to the unload position, the working fluid is not guided from the plurality of fluid pressure pumps to the plurality of actuators, and the plurality of actuator control valves are operated by the pilot pressure of the pilot pump. A fluid pressure control device that can be switched. In the fluid pressure control device according to claim 1,
Further provided with a parallel passage connected to the fluid pressure pump and connected in parallel to the plurality of actuator control valves.
A fluid pressure control device that puts the parallel passage into a non-pressurized state when the switching valve is switched to the unload position. In the fluid pressure control device according to claim 2,
The fluid pressure pump has a first pump that supplies a working fluid to a first circuit system and a second pump that supplies a working fluid to a second circuit system.
The actuator control valve is
A first traveling control valve provided in the first circuit system and a plurality of first working control valves provided on the downstream side of the first traveling control valve.
It has a second traveling control valve provided in the second circuit system and a plurality of second working control valves provided on the downstream side of the second traveling control valve.
The parallel passage is
A first parallel passage connected to the first pump and connected in parallel to the first traveling control valve and the first working control valve, and the second parallel passage connected to the second pump. It has a traveling control valve and a second parallel passage connected in parallel to the second working control valve.
At the first position, the working fluid of the first pump is guided to the first traveling control valve and the first working control valve, and the working fluid of the second pump is guided to the second traveling control valve and the second traveling control valve. Guided by the second working control valve,
At the second position, the working fluid of the first pump is guided to the first traveling control valve and the second traveling control valve, and the working fluid of the second pump is the first working control valve and the first working control valve. Guided by the second working control valve,
The spool has an annular groove provided on the outer peripheral surface and a hollow portion provided inside.
When the spool is in the unload position, a fluid pressure control device in which the working fluid of the first pump is guided to the tank through the annular groove and the working fluid of the second pump is guided to the tank through the hollow portion. .. In the fluid pressure control device according to claim 3,
Further provided with a valve body in which the spool is slidably accommodated.
The hollow portion has a first internal passage extending in the axial direction of the spool and a second internal passage extending from the first internal passage to the outer peripheral surface of the spool.
A fluid pressure control device in which communication between the second pump and the tank is cut off by covering the opening of the second internal passage on the outer peripheral surface of the spool with the inner peripheral surface of the valve body. In the fluid pressure control device according to claim 4,
The valve body has a tank port that communicates with the tank.
The spool has a land portion that shuts off the tank port.
A fluid pressure control device in which communication between the second pump and the tank is cut off by covering the opening of the second internal passage provided in the land portion with the inner peripheral surface of the valve body.

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