JP2019065996A - Hydraulic system of work machine - Google Patents

Abstract

To provide a hydraulic system of a work machine capable of easily lowering output of hydraulic equipment.SOLUTION: A hydraulic system of a work machine includes a hydraulic pump P1 discharging a hydraulic fluid, hydraulic equipment 56 operable by the hydraulic fluid, an operational operation member 58, a first operation valve 59 capable of setting a pressure of the hydraulic fluid according to the operation of the operation member, and a pressure supply portion 60B supplying a first counter pressure of the hydraulic fluid against the first operation pressure as the pressure of the hydraulic fluid set by the first operation valve. Further the hydraulic equipment has a first pressure receiving portion 76a receiving a pressure of the hydraulic fluid, and a second pressure receiving portion 76b receiving the pressure of the hydraulic fluid, the first operation valve can set a first operation pressure of the hydraulic fluid acting on the first pressure receiving portion, and the pressure supply portion can set a first counter pressure acting on the second pressure receiving portion.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hydraulic system of a working machine such as, for example, a skid steer loader and a compact truck loader.

DESCRIPTION OF RELATED ART Conventionally, the working machine disclosed by patent document 1 is known.
The hydraulic system of the working machine disclosed in Patent Document 1 includes an operation member, a hydraulic pump that discharges hydraulic oil, a first oil passage through which hydraulic oil discharged from the hydraulic pump flows, and the first oil passage. An operating valve connected and capable of changing the pressure of the operating oil output according to the operation of the operating member; a hydraulic device operable by the operating oil output from the operating valve; the operating valve; and the hydraulic device A second oil passage to be connected, and a reduction part connected to the second oil passage and capable of reducing the pressure of the hydraulic oil in the second oil passage.

JP, 2017-67100, A

  In the work machine of Patent Document 1, when reducing the output of the hydraulic device, the secondary pressure is reduced by discharging the hydraulic oil (pilot oil) of the second oil passage that controls the hydraulic device. However, if the discharge amount of the hydraulic oil in the second oil passage is increased to lower the secondary pressure, the discharge amount increases relative to the discharge amount of the hydraulic pump that discharges the hydraulic oil, and other hydraulic equipment There has been a problem in that the pilot pressure for controlling the pressure drop and the problem in which the HST charge flow rate is reduced.

  The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide a hydraulic system of a working machine capable of easily reducing the output of hydraulic equipment.

The technical means of the present invention for solving this technical problem are as follows.
The hydraulic system of the working machine is capable of setting the pressure of the hydraulic fluid according to the operation of the hydraulic pump that discharges the hydraulic fluid, the hydraulic device operable by the hydraulic fluid, the operable operating member, and the operating member. And a pressure supply unit for supplying a first opposing pressure of the hydraulic fluid against the first operating pressure which is the pressure of the hydraulic fluid set by the first operating valve.

The hydraulic device has a first pressure receiving portion for receiving pressure of hydraulic oil and a second pressure receiving portion for receiving pressure of hydraulic oil, and the first operation valve is configured to receive the first portion of the hydraulic oil acting on the first pressure receiving portion. The operating pressure can be set, and the pressure supply unit can set the first opposing pressure of the hydraulic oil acting on the second pressure receiving unit.
The pressure supply unit is connected to a first supply oil passage connecting the first operation valve and the first pressure receiving unit, a second supply oil passage connected to the second pressure reception unit, and the hydraulic pump. And a branch oil passage joining the second supply oil passage, and an operating valve provided in the branch oil passage and applying pressure of hydraulic oil to the branch oil passage.

The hydraulic system of the working machine further includes a second operation valve capable of setting a second operation pressure which is the pressure of the hydraulic oil in accordance with the operation of the operation member, separately from the first operation valve, the pressure supply unit And setting a second counter pressure of the hydraulic fluid against the second operating pressure separately from the first counter pressure.
In the hydraulic system of a working machine, the hydraulic device has a first pressure receiving portion for receiving hydraulic oil and a second pressure receiving portion for receiving hydraulic oil, and the first operation valve is disposed on the first pressure receiving portion. The first operating pressure of the operating oil can be set, the second operating valve can set the second operating pressure of the operating oil acting on the second pressure receiving portion, and the pressure supply portion is A first opposing pressure of hydraulic oil that can resist the first operating pressure can be set in the second pressure receiving portion when the first operating pressure is applied to the first pressure receiving portion, and the second When the second operation pressure is applied to the pressure receiving portion, a second opposing pressure of the hydraulic oil that resists the second operation pressure can be set to the first pressure receiving portion.

The pressure supply unit includes a first supply oil passage connecting the first operation valve and the first pressure receiving unit, and a second supply oil passage connecting the second operation valve and the second pressure reception unit. A branch oil passage connected to the hydraulic pump and joining the first supply oil passage and the second supply oil passage, and a branch oil passage provided with pressure of hydraulic fluid in the branch oil passage And an actuating valve to be applied.
The hydraulic system of the work machine allows hydraulic oil supplied from any of the first and second operating valves to flow to either of the first pressure receiving portion and the second pressure receiving portion, and A check valve is provided that prevents hydraulic oil acting on any of the first pressure receiving portion and the second pressure receiving portion from flowing toward either the first operating valve or the second operating valve.

The hydraulic system of the working machine is provided in the first supply oil passage, and is provided in the first discharge oil passage capable of discharging the hydraulic oil of the first supply oil passage, and is provided in the second supply oil passage, A second discharge oil passage capable of discharging the hydraulic oil of the second supply oil passage, and a throttle provided in the first discharge oil passage and the second discharge oil passage.
The hydraulic system of the work machine includes a first shuttle valve for selecting a pressure of hydraulic fluid acting on the first supply oil passage and a pressure of the hydraulic fluid set by the first operation valve, and the second supply oil passage And a second shuttle valve that selects the pressure of the hydraulic fluid acting on the pressure valve and the pressure of the hydraulic fluid set by the second actuating valve.

  According to the present invention, the output of the hydraulic device can be easily reduced.

It is the schematic of the hydraulic system of the traveling system in 1st Embodiment. It is the schematic of the hydraulic system of the working system in 1st Embodiment. It is the schematic which shows the modification of the hydraulic system of the traveling system in 1st Embodiment. It is the schematic of the hydraulic system of the working system in 2nd Embodiment. It is a side view showing a track loader which is an example of a work machine. It is a side view showing a part of truck loader in the state where the cabin was raised.

Hereinafter, a suitable embodiment of a hydraulic system of work machine 1 concerning the present invention is described, referring to drawings suitably.
First Embodiment
Hereinafter, embodiments of the present invention will be described based on the drawings.
FIG. 5 shows a side view of a working machine according to the present invention. In FIG. 5, a compact track loader is shown as an example of a work machine. However, the working machine according to the present invention is not limited to the compact track loader, and may be, for example, another type of loader working machine such as a skid steer loader. In addition, a working machine other than the loader working machine may be used.

  As shown in FIGS. 5 and 6, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a traveling device 5. In the embodiment of the present invention, the front side (left side in FIG. 5) of the driver sitting on the driver's seat 8 of the work machine 1 is forward, the rear side (right side in FIG. 5) of the driver is rear, and the left side The front side of 5) is described as the left, and the right side of the driver (the back side in FIG. 5) is described as the right. Further, the horizontal direction which is a direction orthogonal to the forward direction or the backward direction will be described as the machine width direction. The direction from the central part of the airframe 2 to the right or left will be described as the direction outside the airframe. In other words, the extracorporeal direction is the width direction of the vehicle and is the direction away from the vehicle 2. The direction opposite to the direction outside the aircraft will be described as the direction inside the aircraft. In other words, the inside of the vehicle is the width direction of the vehicle and is the direction approaching the vehicle 2.

The cabin 3 is mounted on the airframe 2. The cabin 3 is provided with a driver's seat 8. The work device 4 is mounted on the machine body 2. The traveling device 5 is provided on the outside of the airframe 2. At the rear of the fuselage 2, a motor 32 is mounted.
The work device 4 includes a boom 10, a work implement 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

  The boom 10 is vertically swingably provided on the right and left sides of the cabin 3. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip end portion (front end portion) of the boom 10 so as to be vertically pivotable. The lift link 12 and the control link 13 support the base (rear portion) of the boom 10 so that the boom 10 can swing up and down. The boom cylinder 14 raises and lowers the boom 10 by expanding and contracting. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

The fronts of the left and right booms 10 are connected to each other by an odd-shaped connecting pipe. The base parts (rear parts) of the booms 10 are connected by a circular connection pipe.
The lift link 12, the control link 13 and the boom cylinder 14 are respectively provided on the left and right sides of the machine body 2 corresponding to the booms 10 on the left and right sides.
The lift links 12 are provided longitudinally at the rear of the base of each boom 10. An upper portion (one end side) of the lift link 12 is rotatably supported about a lateral axis via a pivot (first pivot) 16 near the rear of the base of each boom 10. In addition, the lower part (the other end side) of the lift link 12 is rotatably supported about a lateral axis via a pivot (a second pivot) 17 near the rear of the vehicle body 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

  The upper portion of the boom cylinder 14 is rotatably supported about a lateral axis via a pivot shaft (third pivot shaft) 18. The third pivot shaft 18 is provided at the base of each boom 10 and at the front of the base. The lower portion of the boom cylinder 14 is rotatably supported about a lateral axis via a pivot shaft (fourth pivot shaft) 19. The fourth pivot shaft 19 is provided near the lower portion of the rear of the airframe 2 and below the third pivot shaft 18.

  The control link 13 is provided in front of the lift link 12. One end of the control link 13 is rotatably supported about a lateral axis via a pivot shaft (fifth pivot shaft) 20. The fifth pivot shaft 20 is provided at a position corresponding to the front of the lift link 12 in the airframe 2. The other end of the control link 13 is rotatably supported about a lateral axis via a pivot shaft (sixth pivot shaft) 21. The sixth pivot shaft 21 is the boom 10 and is provided in front of the second pivot shaft 17 and above the second pivot shaft 17.

  Each boom 10 swings up and down around the first pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and the control link 13 by expanding and contracting the boom cylinder 14, and the tip of each boom 10 Rises and falls. The control link 13 swings up and down around the fifth pivot 20 as the booms 10 move up and down. The lift link 12 swings forward or backward around the second pivot shaft 17 as the control link 13 swings up and down.

Instead of the bucket 11, another work tool can be attached to the front of the boom 10. Other working tools are, for example, attachments such as hydraulic crushers, hydraulic breakers, angle blooms, earth augers, pallet forks, sweepers, mowers, snow blowers, and the like (preliminary attachments).
A connecting member 50 is provided at the front of the left boom 10. The connection member 50 is a device that connects the hydraulic device equipped to the spare attachment and the first pipe member such as a pipe provided to the boom 10. Specifically, the first pipe can be connected to one end of the connection member 50, and the second pipe connected to the hydraulic device of the backup attachment can be connected to the other end. Thus, the hydraulic oil flowing through the first pipe passes through the second pipe and is supplied to the hydraulic device.

The bucket cylinders 15 are respectively disposed near the front of each boom 10. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
In the present embodiment, crawler type (including semi crawler type) traveling devices are adopted for the left and right traveling devices 5. In addition, you may employ | adopt the travel apparatus of the wheel type which has a front wheel and a rear wheel.

Next, the hydraulic system of the traveling system will be described.
As shown in FIG. 1, the hydraulic system includes a first hydraulic pump P1, a left traveling motor device (first traveling motor device) 31L, a right traveling motor device (second traveling motor device) 31R, and a motor 32; And a traveling drive unit 34.
The first hydraulic pump P1 can discharge the hydraulic oil stored in the tank 22. The first hydraulic pump P1 is a drive pump driven by the power of the prime mover 32, and is constituted by a fixed displacement gear pump. The first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 storing hydraulic oil may be referred to as a hydraulic oil tank. Further, among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as a pilot oil, and the pressure of the pilot oil may be referred to as a pilot pressure. On the discharge side of the first hydraulic pump P1, an oil passage (discharge oil passage) 40 in which hydraulic oil (pilot oil) flows is provided. In the discharge oil passage (first oil passage) 40, a first travel motor device 31L and a second travel motor device 31R are provided.

The prime mover 32 is composed of an electric motor, an engine and the like. In this embodiment, the prime mover 32 is an engine. The motor 32 may be a hybrid type having an electric motor and an engine, or may have only an electric motor.
The travel drive device 34 drives the first travel motor device 31L and the second travel motor device 31R, and includes a drive circuit (left drive circuit) 34L for driving the first travel motor device 31L, and a second travel And a drive circuit (right drive circuit) 34R for driving the motor device 31R.

  The left drive circuit 34L and the right drive circuit 34R respectively include traveling pumps (traveling hydraulic pumps) 53L, 53R, shifting oil passages 57h, 57i, and a second charge oil passage 57j. The shifting oil passages 57h and 57i are oil passages connecting the traveling pumps 53L and 53R and the traveling motor 36. The second charge oil passage 57j is connected to the transmission oil passages 57h and 57i, and replenishes the hydraulic oil from the first hydraulic pump P1 to the transmission oil passages 57h and 57i.

  The traveling pumps 53L and 53R are swash plate type variable displacement axial pumps driven by the power of the prime mover 32. In other words, the traveling pumps 53L, 53R are traveling actuators that can be operated by hydraulic oil. The traveling pumps 53L and 53R have a forward pressure receiving portion 53a and a reverse pressure receiving portion 53b on which a pilot pressure acts. The pilot pressure applied to the forward pressure receiving portion 53a and the reverse pressure receiving portion 53b changes the angle of the swash plate. By changing the angle of the oblique plate, it is possible to change the output (discharge amount of hydraulic fluid) of the traveling pumps 53L, 53R and the discharge direction of hydraulic fluid.

The first travel motor device 31L is a motor for transmitting power to the drive shaft of the travel device 5 provided on the left side of the machine body 2. The second travel motor device 31R is a motor for transmitting power to the drive shaft of the travel device 5 provided on the right side of the vehicle body 2.
The first traveling motor device 31L includes a traveling motor 36, a forward or backward switching valve 35, and a traveling control valve (hydraulic switching valve) 38. Hydraulic fluid can be supplied to the traveling motor 36, the forward or backward switching valve 35, and the traveling control valve 38.

The traveling motor 36 is a cam motor (radial piston motor). The traveling motor 36 changes the rotation and torque of the output shaft by changing the size of the capacity (motor capacity) at the time of operation.
Next, the hydraulic system of the working system will be described.
As shown in FIG. 2, the hydraulic system includes a plurality of control valves 56 and a working hydraulic pump (second hydraulic pump) P2.

The second hydraulic pump P2 is a pump installed at a position different from that of the first hydraulic pump P1, and is configured by a fixed displacement gear pump. The second hydraulic pump P2 can discharge the hydraulic oil stored in the tank 22. The second hydraulic pump P2 mainly discharges hydraulic oil that operates a hydraulic actuator.
An oil passage (main oil passage) 39 is provided on the discharge side of the second hydraulic pump P2. A plurality of control valves 56 are connected to the main oil passage 39. The control valve 56 is a valve capable of switching the flow direction of the hydraulic oil by the pilot pressure of the pilot oil. Further, the control valve 56 controls (drives) hydraulic devices such as, for example, a boom, a bucket, a hydraulic crusher, a hydraulic breaker, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, a snow blower.

  The plurality of control valves 56 are a first control valve 56A, a second control valve 56B, and a third control valve 56C. The first control valve 56A is a valve that controls a hydraulic cylinder (boom cylinder) 14 that controls a boom. The second control valve 56B is a valve that controls a hydraulic cylinder (bucket cylinder) 15 that controls a bucket. The third control valve 56C is a valve for controlling a hydraulic device (hydraulic cylinder, hydraulic motor) mounted on a preliminary attachment such as a hydraulic crusher, hydraulic breaker, angle bloom, earth auger, pallet fork, sweeper, mower, snow blower etc. is there.

  Each of the first control valve 56A and the second control valve 56B is a pilot-operated direct-acting spool type three-position switching valve. The first control valve 56A and the second control valve 56B are switched by the pilot pressure to the neutral position, a first position different from the neutral position, and a second position different from the neutral position and the first position. The first control valve 56A can be operated by the pressure difference between the hydraulic oil acting on the pressure receiving portion on one side and the other side of the first control valve 56A. Further, the second control valve 56B can be operated by the pressure difference of the hydraulic oil acting on the pressure receiving portion on one side and the other side of the second control valve 56B. The boom cylinder 14 is connected to the first control valve 56A via an oil passage, and the bucket cylinder 15 is connected to the second control valve 56B via an oil passage.

  An oil supply and discharge passage 83 is connected to the third control valve 56C. One end of the oil supply and discharge passage 83 is connected to the oil supply and discharge port of the third control valve 56C, the middle part of the oil supply and discharge passage 83 is connected to the connecting member 50, and the other end of the oil supply and discharge passage 83 is Connected to the hydraulic equipment of the backup attachment. Specifically, the oil supply and discharge passage 83 includes a first oil supply and discharge passage 83a connecting the first supply and discharge port of the third control valve 56C and the first port of the connection member 50. In addition, the oil supply and discharge passage 83 includes a second oil supply and discharge passage 83b that connects the second supply and discharge port of the third control valve 56C and the second port of the connection member 50. That is, by operating the third control valve 56C, hydraulic fluid flows from the third control valve 56C toward the first supply / discharge oil passage 83a, or from the third control valve 56C toward the second supply / discharge oil passage 83b. Hydraulic fluid can flow.

  As shown in FIGS. 1 and 2, the operation (traveling operation) related to traveling of the work machine 1 and the operation (work operation) related to work are performed by the first operating device 47 provided on the left of the driver's seat 8 and And the second operating device 48 provided on the right of the In other words, the first operating device 47 and the second operating device 48 are hydraulic devices for the traveling system (the traveling motor 36, the traveling pumps 53L, 53R), and hydraulic devices for the working system (the first control valve 56A, the second control valve 56B). , The third control valve 56C, the boom cylinder 14, the bucket cylinder 15, the hydraulic cylinder provided in the spare attachment, and the hydraulic motor).

Next, the first operating device 47 and the second operating device 48 will be described in detail.
The first operating device 47 is a device capable of performing both traveling operation and work operation, and has a first operating member 54. A lever capable of performing a first operation of moving the first operation member 54 in the forward or backward direction and a second operation of moving in the left or right direction (body width direction) different from the forward or backward direction It is. In other words, the first operation member 54 is a lever that can be moved in one direction (e.g., front, left) and in another direction (e.g., rear, right) different from one direction.

  In the first operation member 54, the first operation is assigned to the traveling operation, and the second operation is assigned to the work operation. That is, the first operation member 54 doubles as an operation member for traveling (travel operation member) and an operation member for operation (work operation member). The first operation member 54 is not limited to the lever as long as at least the first operation and the second operation can be performed independently.

  A plurality of pilot valves 55 are provided at the lower part of the first operation member 54. The plurality of pilot valves 55 can change the pressure of the hydraulic fluid in accordance with the operation of the first operation member 54. The plurality of pilot valves 55 are a pilot valve 55A, a pilot valve 55B, a pilot valve 55C, and a pilot valve 55D. The pilot valve 55A, the pilot valve 55B, the pilot valve 55C, and the pilot valve 55D are connected to the discharge oil passage 40.

  The pilot valve 55A is a valve operated by the front operation in the first operation (the operation in the front direction or the back direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the front operation. The pilot valve 55B is a valve operated by the rear operation in the first operation (operation in the forward direction or the rear direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the rear operation. That is, the pilot valve 55A and the pilot valve 55B are valves operated by the first operation, and perform movements corresponding to the traveling operation.

  The pilot valve 55C is a valve operated by the left operation in the second operation (operation in the left direction or the right direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the left operation. The pilot valve 55D is a valve operated by the right operation in the second operation (operation in the left direction or the right direction), and the pressure of hydraulic fluid to be output changes according to the operation amount (operation) of the right operation. That is, the pilot valve 55C and the pilot valve 55D are valves operated by the second operation, and perform movements corresponding to the work operation.

  The second operating device 48 is a device capable of performing both traveling operation and work operation, and has a second operating member 58. The second operation member 58 is a lever capable of performing a first operation for moving in the forward or backward direction and a second operation for moving in the left or right direction (body width direction) different from the forward or backward direction It is. In other words, the second operating member 58 is a lever that can be moved in one direction (eg, front, left) and in another direction (eg, back, right) different from one direction.

  In the second operation member 58, the first operation is assigned to the traveling operation, and the second operation is assigned to the work operation. That is, the second operation member 58 doubles as a traveling operation member (traveling operation member) and an operation member (work operation member). The second operation member 58 is not limited to the lever as long as at least the first operation and the second operation can be performed independently.

  A plurality of pilot valves 59 are provided below the second operation member 58. The plurality of pilot valves 59 can change the pressure of the hydraulic fluid in accordance with the operation of the second operation member 58. The plurality of pilot valves 59 are a pilot valve 59A, a pilot valve 59B, a pilot valve 59C, and a pilot valve 59D. The pilot valve 59A, the pilot valve 59B, the pilot valve 59C and the pilot valve 59D are connected to the discharge oil passage 40.

  The pilot valve 59A is a valve operated by the front operation in the second operation (operation in the front direction or the back direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the front operation. The pilot valve 59B is a valve operated by the rear operation in the first operation (operation in the forward direction or the backward direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the rear operation. That is, the pilot valve 59A and the pilot valve 59B are valves operated by the first operation, and perform movements corresponding to the traveling operation.

  The pilot valve 59C is a valve operated by left operation in the first operation (operation in the left direction or right direction), and the pressure of the hydraulic fluid to be output changes according to the operation amount (operation) of the left operation. The pilot valve 59D is a valve operated by the right operation in the second operation (operation in the left direction or the right direction), and the pressure of hydraulic fluid to be output changes according to the operation amount (operation) of the right operation. That is, the pilot valve 59C and the pilot valve 59D are valves operated by the second operation, and perform movements corresponding to the work operation.

  From the above, among the plurality of pilot valves, the pilot valve 55A, the pilot valve 55B, the pilot valve 59A, and the pilot valve 59B operate in response to the traveling operation, and the pilot valve 55C, the pilot valve 55D, the pilot valve 59C, The pilot valve 59D operates in response to work operation. For convenience of explanation, the pilot valve 55A, the pilot valve 55B, the pilot valve 59A, and the pilot valve 59B may be referred to as a traveling pilot valve. Of the traveling pilot valves, the pilot valve 55A that operates in one direction (for example, the front) of the first operation member 54 is referred to as "first pilot valve", and the other direction (for example, the rear) of the first operation member 54 The pilot valve 55B actuated by the first control valve is referred to as a "second pilot valve", and the pilot valve 59A actuated according to one direction (for example, the front) of the second operation member 58 is referred to as a "third pilot valve". The pilot valve 59B that operates in the other direction (for example, after) of the two operation members 58 is referred to as a "fourth pilot valve".

Next, the relationship between the traveling pilot valve, the operation pilot valve, and the hydraulic device will be described. The symbols “W1”, “W2”, “D1” and “D2” shown in FIG. 1 and FIG. 2 indicate connection destinations of the oil passage.
The traveling pilot valve and the traveling pumps 53L and 53R, which are one of traveling hydraulic devices (traveling hydraulic devices), are connected by a traveling oil passage 45. The traveling oil passage 45 includes a first traveling oil passage 45a, a second traveling oil passage 45b, a third traveling oil passage 45c, and a fourth traveling oil passage 45d. The first traveling oil passage 45a is an oil passage connecting the first pilot valve 55A and the forward pressure receiving portion 53a of the traveling pump 53L. The second traveling oil passage 45b is an oil passage connecting the second pilot valve 55B and the backward pressure receiving portion 53b of the traveling pump 53L. The third traveling oil passage 45c is an oil passage connecting the third pilot valve 59A and the forward pressure receiving portion 53a of the traveling pump 53R. The fourth traveling oil passage 45d is an oil passage connecting the fourth pilot valve 59B and the backward pressure receiving portion 53b of the traveling pump 53R.

  When the first operation member 54 is tilted forward, the first pilot valve 55A is operated to output a pilot pressure from the first pilot valve 55A. The pilot pressure acts on the forward pressure receiving portion 53a of the traveling pump 53L. When the second operation member 58 is tilted forward, the third pilot valve 59A is operated to output a pilot pressure from the third pilot valve 59A. The pilot pressure acts on the forward pressure receiving portion 53a of the traveling pump 53R.

  When the first operation member 54 is tilted rearward, the second pilot valve 55B is operated to output a pilot pressure from the second pilot valve 55B. The pilot pressure acts on the reverse pressure receiving portion 53b of the traveling pump 53L. When the second operation member 58 is tilted rearward, the fourth pilot valve 59B is operated to output a pilot pressure from the fourth pilot valve 59B. The pilot pressure acts on the reverse pressure receiving portion 53b of the traveling pump 53R.

  Therefore, when the first operation member 54 and the second operation member 58 are swung forward, the traveling motor (HST motor) 36 is driven at a speed proportional to the swing amount of the first operation member 54 and the second operation member 58. As a result, the working machine 1 goes straight ahead. When the first operating member 54 and the second operating member 58 are swung rearward, the travel motor 36 reverses at a speed proportional to the amount of swing of the first operating member 54 and the second operating member 58, and the result is , The working machine 1 goes straight to the rear.

When one of the first operating member 54 and the second operating member 58 is swung forward and the other is swung backward, the left traveling motor 36 and the right traveling motor 36 move in different directions. As a result, the work implement 1 pivots to the right or left.
As described above, traveling operation for moving the work machine 1 forward, reverse, right turn, left turn by moving the first operation member 54 forward or backward, or moving the second operation member 58 forward or backward It can be performed.

  Further, the work pilot valve and the control valve 56 which is one of the hydraulic equipment (work hydraulic equipment) of the work system are connected by the work oil passage 46. The working oil passage 46 includes a first working oil passage 46a, a second working oil passage 46b, a third working oil passage 46c, and a fourth working oil passage 46d. The first working oil passage 46a is an oil passage connecting the pilot valve 55C and the pressure receiving portion of the first control valve 56A. The second working oil passage 46b is an oil passage connecting the pilot valve 55D and the pressure receiving portion of the first control valve 56A. The third working oil passage 46c is an oil passage connecting the pilot valve 59C and the pressure receiving portion of the second control valve 56B. The fourth working oil passage 46d is an oil passage connecting the pilot valve 59D and the pressure receiving portion of the second control valve 56B.

  When the first operation member 54 is tilted to the left, the pilot valve 55C is operated to set the pilot pressure of the pilot oil output from the pilot valve 55C. The pilot pressure acts on the pressure receiving portion of the first control valve 56A, the boom cylinder 14 is extended, and the boom 10 is raised. When the first operation member 54 is tilted to the right, the pilot valve 55D is operated to set the pilot pressure of the pilot oil output from the pilot valve 55D. The pilot pressure acts on the pressure receiving portion of the first control valve 56A, the boom cylinder 14 contracts, and the boom 10 descends. When the second operation member 58 is tilted to the left, the pilot valve 59C is operated to set the pilot pressure of the pilot oil output from the pilot valve 59C. The pilot pressure acts on the pressure receiving portion of the second control valve 56B, the bucket cylinder 15 contracts, and the bucket 11 squeezes. When the second operating member 58 is tilted to the right, the pilot valve 59D is operated to set the pilot pressure of the pilot oil output from the pilot valve 59D. The pilot pressure acts on the pressure receiving portion of the second control valve 56B, and the bucket cylinder 15 extends, and the bucket 11 performs a dumping operation.

Therefore, by moving the first operation member 54 leftward or rightward or moving the second operation member 58 leftward or rightward, the working operation such as raising and lowering of the boom 10, dumping operation or squee operation of the bucket can be performed. It can be carried out.
The hydraulic system of the working machine 1 includes the pressure supply unit 60A. The pressure supply unit 60A can supply hydraulic fluid (pilot oil) to the traveling pumps 53L and 53R, which are hydraulic devices, to reduce the output of the traveling pumps 53L and 53R. Specifically, the pressure supply unit 60A applies the pressure of the hydraulic oil against the pressure of the hydraulic oil set by the first operation valve based on the operation of the operation member. In the present embodiment, the pressure supply unit 60A is an operation set by any of the pilot valves 55A and 55B and the pilot valves 59A and 59B based on the operation of the first operation member 54 and the second operation member 58 which are operation members. The pressure of the hydraulic oil is exerted against the pressure of the oil.

  For convenience of explanation, in the pressure receiving portions 53a and 53b of the traveling pumps 53L and 53R, one of the two pressure receiving portions 53a and 53b is referred to as a "first pressure receiving portion" and the other pressure receiving portion. It may be called "second pressure receiving unit". Further, the operation valves for applying the pressure of the hydraulic oil to the first pressure receiving portion, that is, the pilot valves 55A and 59A may be referred to as "first operation valves". Further, the operation valve for applying the pressure of the hydraulic oil to the second pressure receiving portion, that is, the pilot valves 55B and 59B may be referred to as a "second operation valve". Further, the pressure of the hydraulic fluid set by the first operation valve, that is, the pressure of the hydraulic fluid acting on the first pressure receiving portion may be referred to as a "first operating pressure". Further, the pressure of the hydraulic fluid set by the second operation valve, that is, the pressure of the hydraulic fluid acting on the second pressure receiving portion may be referred to as a "second operating pressure". Further, the pressure set by the first operating valve and the second operating valve, that is, the pressure set in the first pressure receiving portion and the second pressure receiving portion is referred to as "pilot pressure".

  The pressure supply unit 60A supplies the first opposing pressure to the second pressure receiving unit 53b against the first operation pressure (the pilot pressure acting on the first pressure receiving unit 53a) set by the first operation valves 55A and 59A. (Give. For example, when the first operation pressure which is the pilot pressure acting on the first pressure receiving portion 53a of the traveling pump 53L by operating the first operation member 54 is set by the first operation valve 55A, the pressure supply portion 60A Applies the pilot pressure which is the first opposing pressure to the second pressure receiving portion 53b of the traveling pump 53L.

Further, when the first operation pressure, which is a pilot pressure acting on the first pressure receiving portion 53a of the traveling pump 53R by operating the second operation member 58, is set by the first operation valve 59A, the pressure supply portion 60A Applies a pilot pressure, which is a first opposing pressure, to the second pressure receiving portion 53b of the traveling pump 53R.
Therefore, when the first operating pressure is set in the first pressure receiving portion 53a by either of the first operating valves 55A, 59A, the pressure supply unit 60A sets the first opposing pressure against the first operating pressure as the first operating pressure. It applies to the 2nd pressure receiving part 53b which is the opposite side of the 1st pressure receiving part 53a.

  Further, the pressure supply unit 60A opposes the second opposing pressure to the first pressure receiving unit 53a against the second operation pressure (the pilot pressure acting on the second pressure receiving unit 53b) set by the second operation valves 55B and 59B. Supply to For example, when the second operation pressure, which is a pilot pressure acting on the second pressure receiving portion 53b of the traveling pump 53L by operating the first operation member 54, is set by the second operation valve 55B, the pressure supply portion 60A Applies a pilot pressure, which is a first opposing pressure, to the first pressure receiving portion 53a of the traveling pump 53L.

Further, when the second operation pressure, which is a pilot pressure acting on the second pressure receiving portion 53b of the traveling pump 53R by operating the second operation member 58, is set by the second operation valve 59B, the pressure supply portion 60A Applies the pilot pressure which is the first opposing pressure to the first pressure receiving portion 53a of the traveling pump 53R.
Therefore, when the second operating pressure is set in the second pressure receiving portion 53b by either of the second operating valves 55B and 59B, the pressure supply unit 60A sets the second opposing pressure against the second operating pressure as the second operating pressure. It applies to the 1st pressure receiving part 53a which is the opposite side of the 2nd pressure receiving part 53b.

Hereinafter, the pressure supply unit 60A will be described in detail.
The pressure supply unit 60A has a first supply oil passage and a second supply oil passage. The first supply oil passage is an oil passage connecting the pilot valves 55A, 59A and the pressure receiving portion 53a of the traveling pumps 53L, 53R. Specifically, the first supply oil passage is a traveling oil passage 45. The second supply oil passage is an oil passage connecting the pilot valves 55B and 59B and the pressure receiving portion 53b of the traveling pumps 53L and 53R.

In addition, the pressure supply unit 60A includes a plurality of branch oil passages 64A and a plurality of operation valves 65A. The plurality of branch oil passages 64A are connected to the first hydraulic pump (hydraulic pump) P1 and join the traveling oil passage 45. The plurality of operation valves 65A are provided in the branch oil passage 64A, and apply the pressure of the hydraulic oil to the branch oil passage 64A.
The plurality of operating valves 65A are a first operating valve 65A1 and a second operating valve 65A2. The plurality of branch oil passages 64A are a first branch oil passage 64A1 and a second branch oil passage 64A2.

  The first branch oil passage 64A1 is an oil passage connected to the first hydraulic pump (hydraulic pump) P1 and joining the first traveling oil passage 45a and the third traveling oil passage 45c. The first branch oil passage 64A1 is provided with a first operation valve 65A1. The first operation valve 65A1 is an electromagnetic proportional valve (proportional valve) whose opening degree can be changed by exciting a solenoid. According to the proportional valve 65A1, when the opening degree is changed from the fully closed state, the first pressure receiving portion 53a of the traveling pump 53L and the first of the traveling pump 53R are connected via the first traveling oil passage 45a and the third traveling oil passage 45c. The pilot pressure can be applied to the one pressure receiving portion 53a.

Specifically, when the second operation pressure is applied to the second pressure receiving portion 53b of the traveling pump 53L by the operation of the first operation member 54, the opening degree of the first operation valve 65A1 is changed from the fully closed state. Ru. As a result, it is possible to apply a second opposing pressure against the second operation pressure to the first pressure receiving portion 53a of the traveling pump 53L by the operation of the first operation valve 65A1.
Further, when the second operation pressure is applied to the second pressure receiving portion 53b of the traveling pump 53R by the operation of the second operation member 58, the opening degree of the first operation valve 65A1 is changed from the fully closed state. As a result, it is possible to apply a second opposing pressure against the second operation pressure to the first pressure receiving portion 53a of the traveling pump 53R by the operation of the first operation valve 65A1.

The second opposing pressure set by the first operating valve 65A1 is set to a pressure smaller than the second operating pressure. When the second operation pressure does not act on the second pressure receiving portion 53b of the traveling pumps 53L and 53R, the first operation valve 65A1 is fully closed, and the second opposing pressure is not applied.
As described above, according to the first operation valve 65A1, when the second operation valves 55B and 59B are operated, the second opposing pressure against the second operation pressure set by the second operation valves 55B and 59B is Since it is applied to the traveling pumps 53L, 53R, the output of the traveling pumps 53L, 53R can be reduced without discharging the pilot oil.

  The second branch oil passage 64A2 is an oil passage connected to the first hydraulic pump (hydraulic pump) P1 and joining the second traveling oil passage 45b and the fourth traveling oil passage 45d. The second branch oil passage 64A2 is provided with a second operation valve 65A2. The second operation valve 65A2 is an electromagnetic proportional valve (proportional valve) whose opening degree can be changed by exciting a solenoid. According to the proportional valve 65A2, if the degree of opening is changed from the fully closed state, the second pressure receiving portion 53b of the traveling pump 53L and the traveling pump 53R are connected via the second traveling oil passage 45b and the fourth traveling oil passage 45d. The pilot pressure can be applied to the second pressure receiving portion 53b.

Specifically, when the first operation pressure is applied to the first pressure receiving portion 53a of the traveling pump 53L by the operation of the first operation member 54, the opening degree of the second operation valve 65A2 is changed from the fully closed state. Ru. As a result, by the operation of the second operation valve 65A2, it is possible to apply a first opposing pressure against the first operation pressure to the second pressure receiving portion 53b of the traveling pump 53L.
Further, when the first operation pressure is applied to the first pressure receiving portion 53a of the traveling pump 53R by the operation of the second operation member 58, the opening degree of the second operation valve 65A2 is changed from the fully closed state. As a result, by the operation of the second operation valve 65A2, it is possible to apply a first opposing pressure against the first operation pressure to the second pressure receiving portion 53b of the traveling pump 53R.

The first opposing pressure set by the second operating valve 65A2 is set to a pressure smaller than the first operating pressure. When the first operation pressure does not act on the first pressure receiving portion 53a of the traveling pumps 53L, 53R, the second operation valve 65A2 is fully closed, and the first opposing pressure is not applied.
As described above, according to the second operation valve 65A2, when the first operation valves 55A and 59A are operated, the first counter pressure against the first operation pressure set by the first operation valves 55A and 59A is Since it is applied to the traveling pumps 53L, 53R, the output of the traveling pumps 53L, 53R can be reduced without discharging the pilot oil.

The traveling oil passage 45 has a plurality of first check valves 71 and a plurality of second check valves 72. The plurality of first check valves 71 are provided between a merging portion where the traveling oil passage 45 and the branch oil passage 64A merge and the first operation valves 55A and 59A. Specifically, the first check valve 71 is a first check valve 71a, 71b, 71c, 71d.
The first check valve 71a is provided between the first operation valve 55A and a first junction 66A1 where the traveling oil passage 45a and the branch oil passage 64A1 merge in the traveling oil passage 45a. The first check valve 71c is provided between the first operation valve 59A and a junction 66A2 where the traveling oil passage 45c and the branch oil passage 64A1 join in the traveling oil passage 45c.

The first check valve 71b is provided between the second operation valve 55B and a junction 66A3 where the traveling oil passage 45b and the second branch oil passage 64A2 merge in the traveling oil passage 45b. The first check valve 71d is provided between the second operation valve 59B and a joining portion 66A4 where the traveling oil passage 45d and the second branch oil passage 64A2 join in the traveling oil passage 45d.
The first check valve 71 allows the flow of hydraulic oil from the operation valves (pilot valves) 55A, 55B, 59A, 59B toward the merging portions 66A1, 66A2, 66A3, 66A4, and the merging portions 66A1, 66A2, 66A3, 66A4 Restrict the flow of hydraulic oil from the control valve 55A, 55B, 59A, 59B.

The second check valve 72 is provided in the branch oil passage 64A. The second check valve 72 is a second check valve 72a, 72b, 72c, 72d. The second check valves 72a and 72c are provided in the branch oil passage 64A1. The second check valves 72b and 72d are provided in the second branch oil passage 64A2.
The second check valve 72 allows the flow of hydraulic oil from the operating valve 65A to the merging portion 66A1, 66A2, 66A3, 66A4, and flows the hydraulic oil from the merging portion 66A1, 66A2, 66A3, 66A4 to the operating valve 65A. Regulate.

  Further, as shown in FIG. 1, the traveling oil passage 45 has a plurality of discharge oil passages 78 and a plurality of throttles 79. The discharge oil passage 78 branches from the section between the junctions 66A1, 66A2, 66A3, 66A4 of the traveling oil passage 45 and the traveling pumps 53L, 53R, and discharges the working oil. The discharge oil passage 78 is a discharge oil passage 78a, 78b, 78c, 78d. The plurality of throttles 79 reduce the flow rate of hydraulic fluid. The aperture 79 is configured, for example, by making a part of 78a, 78b, 78c, 78d thinner than the other parts. In other words, the section 78a, 78b, 78c, 78d is configured by making the cross-sectional area of the portion through which the hydraulic oil flows smaller than the other portions.

  The discharge oil passage 78a is an oil passage branched from between the junction 66A1 and the pressure receiving portion 53a in the first traveling oil passage 45a. A throttle 79a is provided in the middle of the discharge oil passage 78a. The discharge oil passage 78c is an oil passage branched from between the junction 66A2 and the pressure receiving portion 53a in the third traveling oil passage 45c. A throttle 79c is provided in the middle of the discharge oil passage 78c. The discharged oil passage 78b is an oil passage branched from between the first junction 66A3 and the pressure receiving portion 53b in the second traveling oil passage 45b. A throttle 79 b is provided in the middle of the discharge oil passage 78 b. The discharge oil passage 78d is an oil passage branched from between the first junction 66A4 and the pressure receiving portion 53b in the fourth traveling oil passage 45d. A throttle 79d is provided in the middle of the discharge oil passage 78d. That is, part of the hydraulic oil flowing through the traveling oil passage 45 can be discharged to the tank 22 through the discharge oil passage 78 and the throttle 79.

  The controller 90 changes the opening degree of the operating valve 65A. The control device 90 is connected to a detection device 91 that detects the load of the motor 32. The detection device 91 receives, for example, an engine speed as an index indicating the load of the motor 32. The control device 90 outputs a control signal for opening the operating valve 65A (the first operating valve 65A1, the second operating valve 65A2) when the engine speed becomes lower than a predetermined value. As a result, the output of the traveling pumps 53L and 53R can be reduced by applying the first opposing pressure and the second opposing pressure to the pressure receiving portions 53a and 53b as described above by opening the actuating valve 65A. Therefore, engine stall can be prevented by the actuating valve 65A. The load on the prime mover 32 is directly measured, and when the load on the prime mover 32 exceeds a predetermined value, the actuating valve 65A is operated to apply the first opposing pressure and the second opposing pressure to the pressure receiving portions 53a and 53b. You may

  The controller 90 has a warm-up mode. The warm-up mode is a mode in which the hydraulic device of the operation system is warmed up without operating the traveling device of the work machine 1. The warm-up mode will be described in detail. In the warm-up mode, the controller 90 causes the pressure of the hydraulic fluid passing through the forward operation valve 65A1 to reach the first traveling oil passage 45a and the second traveling oil passage 45b. The pressure of the hydraulic fluid passing through the actuating valve 65A2 to the third traveling oil passage 45c and the fourth traveling oil passage 45c is set to a pressure lower than the pressure at which the traveling pumps 53L, 53R operate. The hydraulic oil that has passed through the traveling oil passage (first supply oil passage) 45 is discharged to the tank 22 through the discharge oil passage 78 and the throttle 79. Since the hydraulic oil flows through the supply oil passage at a pressure lower than the pressure at which the traveling pumps 53L, 53R operate, the traveling device does not operate. That is, in the warm-up mode, while the work machine 1 is stopped, the hydraulic circuit of the operation system is warmed up.

  Switching to the warm-up mode is performed by a switch 92 connected to the controller 90. The switch 92 is a member for instructing the control device 90 to switch to the warm-up mode. When the switch 92 is pressed, a signal is output to the controller 90 to switch to the warm-up mode. On the other hand, when the switch 92 is pressed again, the warm-up mode is released. The switch 92 is a push button switch 92 such as a momentary switch or an alternate switch. The switch 92 is not limited to the push button switch 92 of the momentary switch or the alternate switch, and may be any switch that outputs a signal to the control device 90. As a result, the hydraulic fluid can be discharged from the discharge oil passage 78 without operating the traveling pumps 53L, 53R. For this reason, it is possible to warm up the oil path of the operation system even when the work implement 1 is not moving or working.

  FIG. 3 shows a modification of the first embodiment. In the modification shown in FIG. 3, the first branch oil passage 64A1 is connected to the first traveling oil passage 45a and the second traveling oil passage 45b, and the second branch oil passage 64A2 is connected to the third traveling oil passage 45c and the fourth traveling. It is a modification connected to oilway 45b. The first branch oil passage 64A1 is provided with a first operation valve 65A1, and the second branch oil passage 64A2 is provided with a second operation valve 65A2.

  The pressure supply unit 60A has a plurality of high pressure selection valves (shuttle valves). The plurality of high pressure selection valves are valves that transmit a higher pressure of at least two inputted pressures. The plurality of high pressure selection valves are 73a, 73b, 73c, 73d. The high pressure selection valve 73a is provided in the merging portion 66A1, and the high pressure selection valve 73b is provided in the merging portion 66A2. The high pressure selection valve 73c is provided in the merging portion 66A3, and the high pressure selection valve 73d is provided in the merging portion 66A4.

In the case of the modification of FIG. 3, when the second operation pressure is applied to the second pressure receiving portion 53b of the traveling pump 53L by the operation of the first operation member 54, the first operation valve 65A1 is opened from the fully closed state Is changed. As a result, it is possible to apply a second opposing pressure against the second operation pressure to the first pressure receiving portion 53a of the traveling pump 53L by the operation of the first operation valve 65A1.
When the second operating pressure is applied to the second pressure receiving portion 53b of the traveling pump 53R by the operation of the second operating member 58, the opening degree of the second operating valve 65A2 is changed from the fully closed state. As a result, it is possible to apply a second opposing pressure against the second operation pressure to the first pressure receiving portion 53a of the traveling pump 53R by the operation of the second operation valve 65A2.

When the first operation pressure is applied to the first pressure receiving portion 53a of the traveling pump 53L by the operation of the first operation member 54, the opening degree of the first operation valve 65A1 is changed from the fully closed state. As a result, it is possible to apply the first opposing pressure against the first operating pressure to the second pressure receiving portion 53b of the traveling pump 53L by the operation of the first operation valve 65A1.
Further, when the first operation pressure is applied to the first pressure receiving portion 53a of the traveling pump 53R by the operation of the second operation member 58, the opening degree of the second operation valve 65A2 is changed from the fully closed state. As a result, by the operation of the second operation valve 65A2, it is possible to apply a first opposing pressure against the first operation pressure to the second pressure receiving portion 53b of the traveling pump 53R.
Second Embodiment
FIG. 4 shows a hydraulic system according to a second embodiment of the present invention. The same components as in the first embodiment are given the same reference numerals, and the description thereof is omitted. The hydraulic system in the second embodiment is a hydraulic system of a working system, for example, a system that supplies another pilot pressure against a pilot pressure received by the second control valve 56B. In addition, the 2nd control valve 56 is an example of hydraulic equipment of a working system, and is not limited.

  The second control valve 56B has a first pressure receiving portion 76a and a second pressure receiving portion 76b. The first pressure receiving portion 76a is connected to a third working oil passage (first supply oil passage) 46c. The second pressure receiving portion 76b is connected to a fourth working oil passage (second supply oil passage) 46d. In other words, the second control valve 56B is controlled by the pilot pressure of the hydraulic fluid supplied to the first pressure receiving portion 76a and the second pressure receiving portion 76b to the neutral position, the first position different from the neutral position, the neutral position and the first position Switches to a different second position.

For convenience of explanation, the operation valve that applies the pressure of the hydraulic fluid to the first pressure receiving portion 76a of the second control valve 56, that is, the pilot valve 59C may be referred to as a "first operation valve". Further, the operation valve for applying the pressure of the hydraulic fluid to the second pressure receiving portion 76b of the second control valve 56, that is, the pilot valve 59D may be referred to as a "second operation valve".
The pressure supply unit 60B has a first supply oil passage and a second supply oil passage. The first supply oil passage is an oil passage connecting the first operation valve 59C and the first pressure receiving portion 76a. The second supply oil passage is an oil passage connecting the second operation valve 59D and the second pressure receiving portion 76b. The first supply oil passage is a third work oil passage 46c, and the second supply oil passage is a fourth work oil passage 46d.

  The pressure supply unit 60B has a branch oil passage 64B and an operation valve 65B. The branch oil passage 64B is an oil passage connecting the hydraulic pump P1 with the third working oil passage 46c and the fourth working oil passage 46d. The branch oil passage 64B is connected to the hydraulic pump P1 and joins the working oil passage. An operating valve 65B is provided in the branch oil passage 64B. The operating valve 65B is an electromagnetic proportional valve (proportional valve) 65B whose opening degree can be changed by exciting a solenoid.

The hydraulic system of the work machine 1 includes a first high pressure selection valve (first shuttle valve) 81 and a second high pressure selection valve (second shuttle valve) 82.
The first shuttle valve 81 is provided at a first junction 66B where the third working fluid passage 46c and the branch fluid passage 64B merge. When the pressure of the hydraulic oil supplied from the first operation valve 59C is larger than the pressure of the hydraulic oil supplied from the operation valve 65B, the first shuttle valve 81 receives the hydraulic oil supplied from the first operation valve 59C. The pressure is supplied to the first pressure receiving portion 76a. On the other hand, when the pressure of the hydraulic oil supplied from the operating valve 65B is larger than the pressure of the hydraulic oil supplied from the first operating valve 59C, the hydraulic oil supplied from the operating valve 65B is supplied to the first pressure receiving portion 76a. Be done.

  The second shuttle valve 82 is provided at a second junction 66C where the fourth working fluid passage 46d and the branch fluid passage 64B merge. If the pressure of the hydraulic oil supplied from the second operation valve 59D is larger than the pressure of the hydraulic oil supplied from the operation valve 65B, the second shuttle valve 82 receives the hydraulic oil supplied from the second operation valve 59D. The pressure is supplied to the second pressure receiving portion 76b. On the other hand, when the pressure of the hydraulic oil supplied from the operating valve 65B is larger than the pressure of the hydraulic oil supplied from the second operating valve 59D, the hydraulic oil supplied from the operating valve 65B is supplied to the second pressure receiving portion 76b. Be done.

  As described above, when the second operation member 58 is tilted to the left, the first operation valve 59C is operated, and the first operation pressure is applied to the first pressure receiving portion 76a by the first operation valve 59C. In this case, the opening degree is changed from the fully closed state of the operating valve 65B. As a result, it is possible to apply the first opposing pressure against the first operating pressure to the second pressure receiving portion 76b of the second control valve 56B by the actuation of the actuation valve 65B.

  On the other hand, when the second operation member 58 is tilted to the right, the second operation valve 59D is operated, and the second operation pressure is applied to the second pressure receiving portion 76b by the second operation valve 59D. In this case, the opening degree is changed from the fully closed state of the operating valve 65B. As a result, it is possible to apply a second opposing pressure against the second operating pressure to the first pressure receiving portion 76a of the second control valve 56B by the actuation of the actuation valve 65B.

  The control device 90 preferably performs control of the actuating valve 65B. As described above, when the second operating member 58 is tilted to the left, the controller 90 sets the pressure set by the operating valve 65B to the pressure set by the first operating valve 59C. Further, even when the second operation member 58 is tilted to the right, the control device 90 sets the pressure set by the operation valve 65B to the pressure set by the second operation valve 59D.

  Therefore, in the second embodiment, the pilot pressure (first opposing pressure, second opposing pressure) applied from the actuating valve 65B is applied to the first pressure receiving portion 76a and the second pressure receiving portion 76b of the second control valve 59B. be able to. Therefore, the output of the second control valve 56B can be reduced. A sufficient amount of hydraulic oil supplied to the HST charge flow rate and the other second control valve 56B can be secured.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all the modifications within the meaning and scope equivalent to the claims.

DESCRIPTION OF SYMBOLS 1 Work machine 45 Traveling oil path 46 Working oil path 54 1st operating member 55 Pilot valve 56B 2nd control valve 58 2nd operating member 59 Pilot valve 60A Pressure supply part 60B Pressure supply part 64A Branching oil path 64B Branching oil path 65A Operation Valve 65B Operating valve 66A 1st junction 66B 1st junction 66C 2nd junction 71 1st check valve 72 2nd check valve 76a 1st pressure receiving portion 76b 2nd pressure receiving portion 78 discharge oil passage 79 throttle 81 1st Shuttle valve 82 2nd shuttle valve P1 1st hydraulic pump

Claims (9)

A hydraulic pump that discharges hydraulic oil,
Hydraulic equipment operable by hydraulic fluid,
An operable operating member,
A first operation valve capable of setting the pressure of the hydraulic fluid according to the operation of the operation member;
A pressure supply unit for supplying a first opposing pressure of the hydraulic fluid against a first operating pressure which is a pressure of the hydraulic fluid set by the first operating valve;
The hydraulic system of the working machine that is equipped with. The hydraulic device has a first pressure receiving portion that receives pressure from the hydraulic fluid, and a second pressure receiving portion that receives pressure from the hydraulic fluid,
The first operation valve can set the first operation pressure of the hydraulic oil acting on the first pressure receiving portion, and the pressure supply portion is configured to oppose the first opposing of the hydraulic oil acting on the second pressure receiving portion. The hydraulic system of a working machine according to claim 1, wherein the pressure can be set. The pressure supply unit
A first supply oil passage connecting the first operation valve and the first pressure receiving portion;
A second supply oil passage connected to the second pressure receiving portion;
A branch oil passage connected to the hydraulic pump and joining the second supply oil passage;
An operating valve provided in the branch oil passage and applying pressure of hydraulic oil to the branch oil passage;
The hydraulic system of the working machine according to claim 2, comprising: A second operation valve capable of setting a second operation pressure, which is the pressure of hydraulic fluid, in accordance with the operation of the operation member, is provided separately from the first operation valve.
The hydraulic system of a working machine according to claim 1, wherein the pressure supply unit sets a second counter pressure of the hydraulic oil against the second operating pressure separately from the first counter pressure. The hydraulic device has a first pressure receiving portion that receives pressure from the hydraulic fluid, and a second pressure receiving portion that receives pressure from the hydraulic fluid,
The first operation valve can set the first operation pressure of the hydraulic oil acting on the first pressure receiving portion,
The second operation valve can set the second operation pressure of the hydraulic oil acting on the second pressure receiving portion,
When the first operation pressure is applied to the first pressure receiving portion, the pressure supply portion can set a first opposing pressure of the hydraulic oil against the first operation pressure to the second pressure receiving portion. When the second operating pressure acts on the second pressure receiving portion, it is possible to set a second opposing pressure of the hydraulic oil to resist the second operating pressure in the first pressure receiving portion. Hydraulic system of the work machine described in. The pressure supply unit
A first supply oil passage connecting the first operation valve and the first pressure receiving portion;
A second supply oil passage connecting the second operation valve and the second pressure receiving portion;
A branch oil passage connected to the hydraulic pump and joining the first supply oil passage and the second supply oil passage;
An operating valve provided in the branch oil passage and applying pressure of hydraulic oil to the branch oil passage;
The hydraulic system of the working machine according to claim 5, comprising:   The hydraulic fluid supplied from any one of the first and second operating valves is allowed to flow to any one of the first pressure receiving portion and the second pressure receiving portion, and the first pressure receiving portion and the second pressure receiving portion The work according to claim 5 or 6, further comprising a check valve that prevents hydraulic oil acting on any of the second pressure receiving portions from flowing toward either the first operating valve or the second operating valve. Machine hydraulic system. A first discharge oil passage provided in the first supply oil passage and capable of discharging the hydraulic oil of the first supply oil passage;
A second discharge oil passage provided in the second supply oil passage and capable of discharging the hydraulic oil of the second supply oil passage;
Throttles provided in the first discharge oil passage and the second discharge oil passage;
The hydraulic system of the working machine according to claim 6, comprising A first shuttle valve that selects the pressure of the hydraulic fluid acting on the first supply oil passage and the pressure of the hydraulic fluid set by the first actuating valve;
A second shuttle valve that selects the pressure of the hydraulic fluid acting on the second supply oil passage and the pressure of the hydraulic fluid set by the second actuating valve;
The hydraulic system of the working machine according to claim 8, comprising

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