JP2513227Y2 - Hydraulic pump controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a hydraulic pump controller.

[Prior Art] Generally, a hydraulically driven construction machine is provided with a plurality of hydraulic motors for operating a hoisting device, a traveling device, a turning device, and other working devices, and a hydraulic oil for supplying hydraulic oil to the hydraulic motors. A plurality of hydraulic pumps are provided, and the plurality of hydraulic pumps are configured to be driven by the same prime mover.

A variable displacement hydraulic pump is used as the hydraulic pump, and the constant torque drive control is performed so that the output of the prime mover driven by a constant torque is distributed to each hydraulic pump to effectively use the output of the prime mover. There is.

FIG. 8 shows an example of a hydraulic pump control device of a mobile crane configured to perform constant torque drive control. In the figure, 1 is each hydraulic motor (not shown) of a right traveling device and a main winding winch device. A variable displacement hydraulic pump for supplying hydraulic oil to the hydraulic pump, a variable displacement hydraulic pump for supplying hydraulic oil to respective hydraulic motors (not shown) of the left traveling device and the auxiliary winch device,
3 is a variable displacement hydraulic pump that supplies pressure oil to a hydraulic motor (not shown) of the swivel device, 4 is an engine that drives the hydraulic pumps 1, 2 and 3, and 18, 19 and 20 are hydraulic oil tanks 21. It is a flow path that connects the hydraulic pumps 1, 2, and 3.

The rated output of the engine 4 is the total of the pump maximum driving forces of the respective hydraulic pumps 1, 2 and 3 (driving force required to drive the pumps so that the hydraulic oil discharge amount becomes maximum in each pump). It is lower than the pump driving force.

The hydraulic pumps 1, 2, 3 are provided with pilot pressure type regulators 8, 9, 10 for adjusting the tilt angles of the swash plates 5, 6, 7 of the hydraulic pumps 1, 2, 3 respectively. Has been.

The regulators 8 and 9 have three pilot chambers, and the regulator 10 has a single pilot chamber.

Each regulator 8, 9, 10 has a pressure oil discharge port of a hydraulic pump 1, 2, 3 provided with the regulator 8, 9, 10 for a flow path 11,
It is connected via 12, 13 and regulators 8, 9, 10 adjust the tilt angle of swash plates 5, 6, 7 according to the discharge pressure of each hydraulic pump 1, 2, 3 itself, Each hydraulic pump 1, 2, 3 can be driven with a driving force that is less than or equal to the set maximum pump input.

Further, the regulator 8 is connected to the flow passages 14 and 15 branching from the flow passages 12 and 13, so that the discharge pressures of the hydraulic pumps 2 and 3 other than the hydraulic pump 1 become a predetermined value or more. At some times, the regulator 8 adjusts the tilt angle of the swash plate 5 to reduce the amount of hydraulic oil discharged from the hydraulic pump 1.
The driving force required to drive the motor can be reduced.

Similarly, the flow passages 16 and 17 branching from the flow passages 11 and 15 are connected to the regulator 9 so that the discharge pressure of the hydraulic pumps 1 and 3 other than the hydraulic pump 2 becomes a predetermined value or more. In this case, the regulator 9 can adjust the tilt angle of the swash plate 6 to reduce the amount of hydraulic oil discharged from the hydraulic pump 2 and reduce the driving force required to drive the hydraulic pump 2. There is.

On the other hand, the hydraulic pump 3 is, as described above,
Since the tilt angle of the swash plate 7 is adjusted only by the discharge pressure of itself, the driving force of the engine 4 does not depend on the discharge pressure of the other hydraulic pumps 1 and 2, and the swing device Hydraulic pump 3 that supplies pressure oil to a hydraulic motor (not shown)
Is transmitted with priority, and the remaining driving force is distributed and transmitted to the hydraulic pumps 1 and 2.

Therefore, in the mobile crane having the above hydraulic pump control device, even if a combined operation of simultaneously performing the turning operation and the traveling or hoisting operation is performed, the hydraulic pump (not shown) of the turning device receives the hydraulic pump 3 from the hydraulic pump 3. Since the hydraulic oil is supplied in a stable state, the suspended load will not be shaken due to the change in the hydraulic oil discharge amount.

[Problems to be Solved by the Invention] However, in recent years, there has been a demand for increasing the number of hydraulic pumps with the diversification of equipment for mobile cranes.

However, in the case where the regulators 8 and 9 having a plurality of pilot chambers are used as in the hydraulic pump control device described above, in order to increase the number of hydraulic pumps, a hydraulic pump other than the hydraulic pump that preferentially transmits the driving force of the engine is used. The number of regulator pilot chambers must be increased, which complicates the structure of the regulator.

In addition, since a regulator having a complicated structure must be provided for all of a large number of hydraulic pumps other than the hydraulic pump that preferentially transmits the driving force of the engine, there is a problem that the manufacturing cost increases.

The present invention solves the above-mentioned problems, and in a hydraulic circuit in which a plurality of variable displacement hydraulic pumps are driven by the same prime mover, constant torque drive control is possible without complicating the structure of the regulator. The purpose is to be able to do.

[Means for Solving the Problems] In order to achieve the above object, in the hydraulic pump control device of the present invention, three or more variable displacement hydraulic pumps 1, 2, 3, driven by the prime mover 4 are used. 22 and each hydraulic pump 1,2,3,
22 swash plates or regulators 24,25,2 with a single pilot chamber for adjusting the tilt angle of the swash shafts 5,6,7,23
6, 27 and a communication position for communicating three or more inlet ports 111, 112, 113, 114 communicating with the main spool chamber 31 via the passage portions 36, 37 with one outlet port 57 and the outlet port.
A switching valve 60 having a main spool 50 set at a blocking position for blocking the communication of the inlet ports 111, 112, 113, 114 with respect to 57 and an elastic body 56 for urging the main spool 50 to the blocking position, and a pilot spool chamber 62. When fluid pressure is applied to any of the formed pilot chambers 67, 68, 69, 70, the main spool 50 of the switching valve 60 communicates with the inlet port 111, 112, 113, 114 and the outlet port 57 from the cutoff position. An actuator 81 having a pilot spool 79 that can be moved to the communication position is provided, and the inlet ports 111, 112, 113, 114 of the switching valve 60 and the pilot chamber 7 of the actuator 81 are provided.
0,69,68,67 communicate with the inlet port 111,11 of the switching valve 60.
Check valves 115, 116, 117, 118 for blocking the flow of fluid from the main spool chamber 31 to the inlet ports 111, 112, 113, 114 are provided between the 2, 113, 114 and the main spool chamber 31, and the hydraulic oil discharge ports of the hydraulic pumps 1, 2, 3, 22 are provided. The ingress port 111,114,
It is connected to 113,112, the pilot chamber of the regulators 24,25,27 attached to the other hydraulic pumps 1,2,22 excluding the hydraulic pump 3 which should preferentially transmit the driving force of the prime mover 4 is a switching valve 60.
Of the hydraulic pump 3 to which the driving force of the prime mover 4 is preferentially transmitted, is connected to the pilot chamber of the regulator 26 attached to the hydraulic pump 3.

[Operation] In the hydraulic pump control device of the present invention, when the variable displacement hydraulic pumps 1, 2, 3, 22 are driven by the prime mover 4, the fluid discharged by the hydraulic pumps 1, 2, 3, 22 is controlled. Inlet port 111 of valve 29,
Pilot chamber 70 of actuator 81 via 114, 113, 112
It flows into 67,68,69.

When the discharge pressure of part or all of the hydraulic pumps 1, 2, 3, 22 exceeds a predetermined value, the fluid flowing into the pilot chambers 70, 67, 68, 69 causes the pilot spool 79 of the actuator 81 to elastically move. The main spool 50 of the switching valve 60 is set to the communicating position against the repulsive force of the body 56, and the inlet side ports 111, 11
The fluid flowing in from 2,113,114 is discharged from the outlet port 57, and the regulator 24,25 of the other hydraulic pumps 1,2,22 excluding the hydraulic pump 3 that preferentially transmits the driving force of the prime mover 4 by the fluid pressure. , 27 actuate, and the fluid discharge amount of the hydraulic pumps 1, 2, 22 decreases.

On the other hand, only the fluid discharged by the hydraulic pump 3 itself flows into the regulator 26 of the hydraulic pump 3 that preferentially transmits the driving force of the prime mover 4.

Therefore, the fluid discharge amount of the hydraulic pump 3 is the same as that of other hydraulic pumps.
It is adjusted by the discharge pressure of the hydraulic pump 3 itself without being influenced by the discharge pressure of 1, 2, 22.

Therefore, the driving force of the prime mover 4 is preferentially transmitted to the hydraulic pump 3, and the remaining driving force is distributed and transmitted to the hydraulic pumps 1, 2, 22.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

1 to 7 show an embodiment of the hydraulic pump control device of the present invention, in which 1 is hydraulic oil for each hydraulic motor (not shown) of the right traveling device and the main winch device. A variable displacement hydraulic pump for supplying pressure oil, 2 is a variable displacement hydraulic pump for supplying pressure oil to the hydraulic motors (not shown) of the left traveling device and the auxiliary winding winch device, and 3 is a hydraulic motor of the turning device (not shown). No.) is a variable displacement hydraulic pump for supplying pressure oil to the hydraulic pump, 22 is a variable displacement hydraulic pump for supplying hydraulic oil to a hydraulic motor (not shown) of the boom hoisting device, and 4 is a hydraulic pump 1, 2, 3, 22. 24,25,26,27 is a regulator equipped with a single pilot chamber for adjusting the tilt angle of the swash plates 5,6,7,23 of the hydraulic pumps 1,2,3,22. , 18,19,20,28 are flow paths connecting the hydraulic oil tank 21 and the hydraulic pumps 1,2,3,22, and 29 is the driving force of the engine 4 to the hydraulic pumps 1,2,3,22. Min to a control valve for controlling a constant torque drive.

 The structure of the control valve 29 will be described with reference to FIGS. 2 to 7.

The body 30 has a main spool chamber 31 penetrating from a front (A side) end surface of the body 30 to a rear (B side) end surface thereof, and a check valve mounting hole 3 extending downward from the upper surface of the body 30.
2, 33, and check valve mounting holes 34, 35 extending upward from the lower surface of the body 30 and communicating with the check valve mounting holes 32, 33,
A flow path 38 penetrating from the communicating portion 36 of the check valve mounting holes 32, 34 to the front-rear intermediate portion of the main spool chamber 31, and the communicating portion 37 of the check valve mounting holes 33, 35 in the longitudinal direction of the main spool chamber 31. Flow path 39 passing through the front-rear direction intermediate portion of 31
And a large diameter portion 4 formed from the rear (B side) end surface of the body 30 to the intermediate portion in the vertical direction of the check valve mounting holes 32, 33, 34, 35.
Channels 44, 45, 46, 47 penetrating to 0, 41, 42, 43 and a drain discharge port 48 penetrating from the side surface of the body 30 to the rear side (B side) end of the main spool chamber 31. Yes (Figs. 2 and 3
(See Figures, 4 and 5).

Female threaded portions 49 are provided on the inner peripheral surfaces of the check valve mounting holes 32 and 33 near the upper surface of the body 30 and the inner peripheral surfaces of the check valve mounting holes 34 and 35 near the lower surface of the body 31.

The main spool 50 is inserted into the main spool chamber 31 so as to be slidable in the front-rear direction (see FIG. 3).

At the front (A side) end of the main spool 50, there is a spring outer fitting portion 51 having an outer diameter smaller than that of the other portion, and at the rear (B side) end of the main spool 50, there is a circumferential direction. A groove portion 52 that extends to is formed.

Further, in the main spool 50, the flow path 53 extending from the front (A side) end surface of the main spool 50 toward the rear side (B side) and the spring outer fitting portion 51 in the radial direction are passed through the flow path 53. A channel 54 communicating with the channel 53 and a channel 55 penetrating the groove 52 in the radial direction and communicating with the channel 53 are provided.

The rear side (B side) end portion of the coil spring 56 extending coaxially with the main spool 50 is externally fitted to the spring outer fitting portion 51, and the front side (A side) end surface to the rear side (B side).
Front block having an outlet port 57 penetrating to the end face
The body 30 is so arranged that the front end (A side) of the coil spring 56 is brought into contact with the inner part of the spring receiving portion 59 opened to the rear end (B side) of the front block 58.
The switching valve 60 is formed by being fixedly attached to the front (A side) end surface of the (see FIG. 2 and FIG. 3).

The main spool 50 is constantly urged to the rear side (B side) by the repulsive force of the coil spring 56, and the portion on the front side (A side) of the groove portion 52 of the main spool 50 and the main passages 38 and 39 are connected to each other. The position is set to a blocking position that blocks communication with the spool chamber 31.

Further, when the main spool 50 is biased to the front side (A side) against the repulsive force of the coil spring 56, the groove portion 52 of the main spool 50 faces the flow paths 38 and 39, and the check valve is attached. The holes 32, 33, 34 and 35 are connected to the communicating portions 36 and 37 and the flow paths 38 and 3.
9, the groove 52, the flow paths 55, 53, 54, and the spring receiving portion 59 are set to a communication position that communicates with the outlet port 57 (see FIGS. 3 and 5). .

A pilot block 62, which penetrates from a front (A side) end surface of the rear block 61 to a rear (B side) end surface, is provided in a rear block 61 that can come into contact with a rear (B side) end portion of the body 30. In the pilot spool chamber 62, a plurality of annular slidable portions 63, 64, 65, 66 are provided coaxially with the pilot spool chamber 62 at predetermined intervals in the front-back direction of the pilot spool chamber 62. Pilot chambers 67, 68, 69, 70 are formed on the rear side (B side) of each of the annular slid parts 63, 64, 65, 66 (second
FIG. 3, FIG. 3).

Further, passages 71, 72, 73, 74 are formed in the rear block 61 from the front (A side) end surface of the rear block 61 to the pilot chambers 67, 68, 69, 70 (see FIG. 6). ).

The flow paths 71, 72, 73, 74 are located on the front side of the rear block 61 (A
When the (side) end surface is brought into contact with the rear side (B side) end surface of the body 30, it can communicate with the flow paths 47, 46, 45, 44 formed in the body 30 (first). (See FIGS. 2 and 3).

In the pilot spool chamber 62, the annular sliding parts 63, 64,
A pilot spool 79 having valve bodies 75, 76, 77, 78 that can be inscribed in 65, 66 is slidably inserted in the front-rear direction, and the rear end (B side) end of the pilot spool chamber 62 is plugged. It is closed by 80 to form the actuator 81.

A stopper 82 is provided on the outer peripheral surface of the front end side (A side) of the pilot spool 79 so as to contact the front end side (A side) of the rear block 62.
A ball 83 is fitted on the front end surface (A side) of 79.

An actuator is provided on the rear (B side) end surface of the switching valve 60.
The front side (A side) end surface of 81 is brought into contact with and fixed to the flow passages 44, 45, 46, 47 so that the flow passages 74, 73, 72, 71 can communicate with each other, and the rear side of the main spool 50. The ball 83 on the front (A side) end surface of the pilot spool 79 is allowed to contact the side (B side) end surface, and the check valve mounting holes 32, 33, 3 are further provided.
4, check valve units 84, 85, 86, 87 having inlet ports 111, 112, 113, 114 at the base end are attached to the control valve 29 so that fluid does not flow out of the main spool chamber 31 to the outside of the body 30. Form.

The structure of the check valve units 84, 85, 86, 87 will be described with reference to FIG.

The check valve units 84, 85, 86, 87 include a valve body 90 having a substantially same shape as a hexagonal bolt in which a hexagonal head portion 89 is integrally formed at the base end portion of a rod-shaped body 88.
From the base end side (C side) end face of the valve body 90 to the tip end side (D side), and the tip end side (D side) end face of the valve body 90 to the base end side (C side). ), The poppet chamber 92 communicating with the pressure oil supply passage 91, and the rod-shaped portion 88.
Of the pressure oil supply passage 91 that radially penetrates the intermediate portion in the longitudinal direction of
And a flow path 93 communicating with the.

The hexagonal head portion 89 of each of the check valve units 84, 85, 86, 87 has inlet ports 111, 112, 113, 114 formed therein.

A body 30 is provided on the outer peripheral surface of the rod-shaped portion 88 on the base end side (C side).
Internal thread 4 of check valve mounting holes 32, 33, 34, 35 drilled in
A male thread portion 94 that can be screwed into the 9 is formed, and the check valve units 84, 85, 86, 87 are attached to the check valve mounting holes 32, 33, 34, 35.
When screwed in, the large diameter portions 40, 4 formed on the intermediate portion in the longitudinal direction of the rod-shaped portion 88 and the inner peripheral surfaces of the check valve mounting holes 32, 33, 34, 35.
An annular space 95 is formed between 1, 42 and 43, and the annular space 95
Through the previous term flow channel 93 and the body 30 through the flow channels 44, 45,
It can communicate with 46 and 47.

The poppet chamber 92 has an inner diameter larger than that of the pressure oil supply passage 91, and the upper end of the poppet chamber 92 is formed in a tapered shape in which the inner diameter gradually decreases toward the base end side (C side) of the valve body 90. ing.

A spring fitting portion of the poppet chamber 92 is formed in a taper shape such that a base end side (C side) end thereof can abut the top end of the poppet chamber 92 and opens toward a tip end side (D side) end. A poppet 96 having 97 is slidably inserted in the axial direction, and the check valves 115, 116, 117, 118 are provided for each of the check valve units 84, 85, 86, 87 in the poppet 96 and the poppet chamber 92.
Is formed.

The poppet 96 is provided with a flow passage 98 that penetrates in the radial direction and communicates with the spring fitting portion 97.

An annular retainer 99 is provided at the tip end side (D side) end of the poppet chamber 92 via a snap ring 100.
The poppet 96 is attached so as not to fall off further, and the poppet 96 is repelled by the repulsive force of the coil spring 101 interposed between the base end side (C side) end surface of the retainer 99 and the inner part of the spring fitting portion 97. Is constantly urged to come into contact with the upper end of the poppet chamber 92, and when the fluid pressure pushes the poppet 96 toward the tip side (D side) against the repulsive force of the coil spring 101, the pressure oil supply passage 91 and body 3 channel 3
It can communicate with 8,39.

Inlet port 1 of each check valve unit 84,85,86,87
The hydraulic oil discharge ports of the hydraulic pumps 1, 22, 3, 2 are connected to 11, 112, 113, 114 via the flow paths 102, 103, 104, 105, respectively.
The hydraulic oil discharged by 22,3,2 is flow paths 44, 45, 46, 47, and flow path 7
It is made possible to flow into the pilot chambers 70, 69, 68, 67 via 4, 73, 72, 71 (see FIGS. 1 and 3).

The outlet port 57 is connected to the regulator 24 of the hydraulic pump 1 via the flow passage 106, and the flow passage 106 is connected to the regulators 27 and 25 of the hydraulic pumps 22 and 2 via the flow passages 107 and 108.

Further, the regulator 26 of the hydraulic pump 3 is connected to the passage 104 via the passage 109 so that the hydraulic oil discharged by the hydraulic pump 3 itself can flow into the regulator 26.

In the figure, 110 indicates a flow path connecting the drain outlet 48 and the hydraulic oil tank 21.

The operation of one embodiment of the hydraulic pump controller of the present invention will be described below.

When the hydraulic pumps 1, 22, 3, 2 are driven by starting the engine 4, the hydraulic oil discharged by the hydraulic pumps 1, 22, 3, 2 is
After passing through 102, 103, 104, 105 and check valve units 84, 85, 86, 87, they flow into the flow paths 38, 39 from the communicating portions 36, 37 of the switching valve 60.

In addition, a part of the hydraulic oil discharged from the hydraulic pumps 1, 22, 3, 2 flows from the check valve units 84, 85, 86, 87 to the flow channels 44, 45, 4
6, 47, and flow paths 74, 73, 72, 71 to flow into the pilot chambers 70, 69, 68, 67 of the actuator 81.

At this time, when the discharge pressure of a part or all of the hydraulic pumps 1, 22, 3, 2 rises above a predetermined value, the hydraulic oil flowing into the pilot chambers 70, 69, 68, 67 becomes the coil spring 56.
The pilot spool 79 and the main spool 50 are pushed to the front side (A side) against the repulsive force of the switch valve 60, and the groove 52 of the main spool 50 is set to the communication position.
Opposite 9

When the groove portion 52 faces the flow paths 38, 39, the hydraulic oil flowing into the flow paths 38, 39 is the flow paths 55, 53, 54, the spring receiving portion 59, the outlet port 57, the flow path 106, the flow path 107, It flows into the regulators 24, 27, 25 via the flow path 108, and the tilt angles of the swash plates 5, 23, 6 of the hydraulic pumps 1, 22, 2 are changed by the regulators 24, 27, 25. , 2 is adjusted so that the hydraulic oil discharge rate decreases.

On the other hand, the regulator 26 of the hydraulic pump 3 has a flow path 104,
Due to 109, only the hydraulic oil discharged by the hydraulic pump 3 itself flows in.

Therefore, the tilt angle of the swash plate 7 of the hydraulic pump 3 is adjusted by the discharge pressure of the hydraulic pump 3 itself without depending on the discharge pressure of the other hydraulic pumps 1, 22 and 2. Is preferentially transmitted to the hydraulic pumps 1, and the remaining driving force is distributed and transmitted to the hydraulic pumps 1, 22 and 2.

Thus, in the present invention, each hydraulic pump 1, 2, 3,
A constant torque that distributes the driving force of the engine 4 to the hydraulic pumps 1, 2, 3, 22 driven by the same engine 4 without complicating the structure of the regulators 24, 25, 26, 27 of 22. Drive control can be performed.

The hydraulic pump control device of the present invention is not limited to the above-described embodiment, but the body 30 and the rear block 61 are integrally formed, and the main spool 50 and the pilot spool 79 are integrally formed. It is needless to say that various modifications can be made within the scope not departing from the gist of the present invention, such as the above-mentioned formation, and the use of an oblique shaft type variable displacement hydraulic pump as the hydraulic pump.

[Advantages of the Invention] As described above, according to the hydraulic pump control device of the present invention, various excellent effects as described below can be obtained.

(1) Regulators 24, 25, each of which has a single pilot chamber for adjusting the tilt angle of the swash plate or the swash shaft 5, 6, 7, 23 in each of the hydraulic pumps 1, 2, 3, 22 26, 27 are provided, and the switching valve 60 is switched by the actuator 81 which operates by the discharge pressure of the hydraulic pumps 1, 2, 22 other than the hydraulic pump 3 which should preferentially transmit the driving force of the prime mover 4, The hydraulic pressure for transmitting the driving force of the prime mover 4 by giving the discharge pressure of the other hydraulic pumps 1, 2, 22 to the regulators 26, 25, 27 associated with them via the switching valve 60. Since the discharge pressure of the other hydraulic pumps 1, 2 and 22 excluding the pump 3 is adjusted, the regulator
It is possible to perform constant torque drive control of the hydraulic pump 3 to preferentially transmit the drive force of the prime mover 4 without complicating the structure of 24, 25, 26, 27.

(2) Since the structure of the regulators 24, 25, 26, 27 does not become complicated, it is possible to reduce the manufacturing cost of the hydraulic pump controller and the maintenance labor.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the hydraulic pump control device of the present invention, FIG. 2 is a side view of the control valve 29 in FIG. 1, and FIG. 3 is a III-III arrow of FIG. FIG. 4, FIG. 4 is a view taken along the line IV-IV in FIG. 2, FIG. 5 is a view taken along the line V-V in FIG. 2, and FIG. 6 is a view taken along the line VI-VI in FIG. FIG. 8 is a detailed view of the check valve units 84, 85, 86, 87 in FIGS. 2 and 5, etc., and FIG. 8 is a hydraulic circuit diagram of a conventional mobile crane. In the figure, 1,2,3,22 are variable displacement hydraulic pumps (variable displacement hydraulic pumps), 4 are engines (motors), 5,6,7,23 are swash plates (swash shafts), 24,25 , 26, 27 are regulators, 29 is a control valve, 3
1 is a main spool chamber, 36 and 37 are communicating portions, 50 is a main spool, 57 is an outlet port, 60 is a switching valve, 62 is a pilot spool chamber, 67, 68, 69 and 70 are pilot chambers, 79 is a pilot spool , 81 is an actuator, 111, 112, 113, 114
Indicates an inlet port, and 115, 116, 117, 118 indicate check valves.

Claims (1)

(57) [Scope of utility model registration request] 1. Three or more variable displacement type hydraulic pumps (1), (2), (3) and (22) driven by a prime mover (4), and each hydraulic pump (1) (2) (3). Regulator (24) (2) equipped with a single pilot chamber for adjusting the tilt angle of the swash plate (22) or swash shaft (5) (6) (7) (23)
5) (26) (27) and three or more inlet ports (111) (112) (113) (114) communicating with the main spool chamber (31) via passage portions (36) (37). One outgoing port (5
7) has a communication position for communicating with the main spool (50) and a main spool (50) set at a blocking position for blocking communication of the inlet ports (111) (112) (113) (114) with the outlet port (57). A switching valve (60) having an elastic body (56) for urging the main spool (50) to a shutoff position, and a plurality of pilot chambers (67) (6) formed in a pilot spool chamber (62).
8) When fluid pressure is applied to any of (69) and (70), the main spool (50) of the switching valve (60) is moved from the shut-off position to the inlet port (111) (112) (113) (114). ) And the outlet port (57) communicate with each other, and an actuator (81) having a pilot spool (79) that can be moved to a communicating position, and the inlet port (111) (112) (113) of the switching valve (60). )
Pilot chamber (70) for (114) and actuator (81)
(69) (68) (67) are communicated with each other, and the main spool chamber is provided between the inlet ports (111) (112) (113) (114) of the switching valve (60) and the main spool chamber (31). Check valves (115) (116) (117) (118) that prevent the flow of fluid from the (31) to the inlet ports (111) (112) (113) (114) are provided, and each hydraulic pump (1) ) (2) (3) (22) hydraulic oil discharge port is connected to the inlet port (111) (114) (113) (112), the liquid that should preferentially transmit the driving force of the prime mover (4) Hydraulic pumps other than the pressure pump (3) (1) (2) (2
Connect the pilot chamber of the regulator (24) (25) (27) attached to 2) to the outlet port (57) of the switching valve (60),
The hydraulic oil discharge port of the hydraulic pump (3) for preferentially transmitting the driving force of the prime mover (4) is connected to a pilot chamber of a regulator (26) attached to the hydraulic pump (3). Hydraulic pump controller.