JP6498571B2 - Working machine hydraulic system - Google Patents

Description

  The present invention relates to a hydraulic system for work machines such as a skid steer loader, a compact truck loader, and a backhoe.

Conventionally, there is one disclosed in Patent Document 1 as a technique for warming up a work machine.
The work machine of patent document 1 is provided with the pilot pressure control valve which controls the pressure of the pilot oil discharged from a pump and sent to a supply object, and the valve body in which this pilot pressure control valve was incorporated. In Patent Document 1, the valve body is provided with a heat-up oil passage through which the pilot oil discharged from the pump is introduced, and the pilot oil introduced into the heat-up oil passage is caused to flow to the hydraulic oil tank via a relief valve or a throttle. Heats up the valve body.

JP2013-117253A

In the working machine of Patent Document 1, the valve body must be processed for warm-up, and a hydraulic circuit that connects the relief valve or the throttle must be formed in the valve body.
The present invention has been made to solve the above-mentioned problems of the prior art, and provides a working machine hydraulic system capable of easily warming up and a working machine equipped with the hydraulic system. The purpose is to do.

The technical means of the present invention for solving this technical problem is as follows.
A hydraulic system of a work machine includes a hydraulic pump that discharges hydraulic oil, a tank that stores hydraulic oil, a hydraulic device that is operated by the hydraulic oil, and a valve that can control the hydraulic device. A control valve capable of switching the flow direction of the working oil by the pilot pressure of the pilot oil that is used as a working oil, and a proportional valve for setting the pilot pressure of the pilot oil supplied to the control valve and supplied to the control valve And an operation member for operating the hydraulic device by changing an opening degree of the proportional valve according to an operation amount, a first oil passage connecting the proportional valve and the control valve, and the first oil a second oil passage for connecting the a road tank, when not operating the operation member, switching of the pilot pressure to be applied to the control valve by the proportional valve, switching of the control valve is carried out And a, a first setting unit capable of setting a pressure greater than zero and less than.

The working machine hydraulic system is a hydraulic pump that discharges hydraulic oil, a tank that stores hydraulic oil, a hydraulic device that is operated by hydraulic oil, and a valve that can control the hydraulic device, the opening of which varies. A control valve capable of switching the flow direction of the hydraulic oil, and an operation member that operates the hydraulic device by switching the control valve when operated, and a first valve that connects the control valve and the hydraulic device. When the three oil passages, the fourth oil passage connecting the third oil passage and the tank, and the operation member are not operated, the opening of the control valve is switched to the control valve. And a second setting unit that can be set to a value that is less than the switching opening and greater than zero .

The hydraulic system of the work machine can set a hydraulic pump that discharges hydraulic oil, a tank that stores hydraulic oil, an operation member, and a pilot pressure that is a pressure of hydraulic oil that is output in accordance with the operation of the operation member. The operation valve having a port connected to the tank, the fifth oil passage connecting the operation valve and the hydraulic pump, and the pressure of the hydraulic oil connected to the fifth oil passage toward the operation valve are changed. A possible first operating valve, a control valve capable of switching a flow direction of hydraulic oil by the pilot pressure set by the operating valve, a sixth oil passage connecting the operating member and the control valve, The maximum value of the pilot pressure output from the operation valve is set by setting the pressure of the hydraulic oil of the seventh hydraulic path connecting the fifth hydraulic path and the sixth hydraulic path and the first hydraulic valve to a predetermined value. , Set below the switching pressure at which the control valve is switched Includes a third setting unit that ability, the.

The hydraulic system of the work machine can set a hydraulic pump that discharges hydraulic oil, a tank that stores hydraulic oil, an operation member, and a pilot pressure that is a pressure of hydraulic oil that is output in accordance with the operation of the operation member. The operation valve having a port connected to the tank, the fifth oil passage connecting the operation valve and the hydraulic pump, and the pressure of the hydraulic oil connected to the fifth oil passage toward the operation valve are changed. A first hydraulic valve that can be operated, a hydraulic device that can be operated by the pilot pressure set by the operation valve, an eighth oil passage that connects the operation valve and the hydraulic device, and a fifth oil passage. The section between the operation valve and the first operating valve, the ninth oil path connecting the eighth oil path, and the pressure of the hydraulic oil of the first operating valve are set to a predetermined value. The maximum pilot pressure output from the operation valve There has been and a fourth setting unit that can set below working pressure to operate.

The hydraulic system of the work machine can set a hydraulic pump that discharges hydraulic oil, a tank that stores hydraulic oil, an operation member, and a pilot pressure that is a pressure of hydraulic oil that is output in accordance with the operation of the operation member. And an operation valve having a port connected to the tank, a fifth oil passage connecting the operation valve and the hydraulic pump, a hydraulic device operable by the pilot pressure set by the operation valve, and the operation An eighth oil passage connecting the valve and the hydraulic device, a tenth oil passage connecting the eighth oil passage and the fifth oil passage, and being connected to the tenth oil passage toward the hydraulic device A second operating valve capable of changing the pressure of the hydraulic oil; and a fifth setting unit capable of setting the pressure of the hydraulic oil by the second operating valve to be lower than the operating pressure at which the hydraulic device operates.

The hydraulic system of the work machine includes a throttle portion that reduces the flow rate of the hydraulic oil flowing through the second oil passage.
The hydraulic system of the work machine includes a throttle unit that reduces the flow rate of the hydraulic oil flowing through the fourth oil passage.
The hydraulic system of the work machine includes a measuring device that measures the temperature of the hydraulic oil, and the first setting unit is configured to control the control when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. The pilot pressure applied to the valve is kept below the switching pressure.

The hydraulic system of the work machine includes a measuring device that measures the temperature of the hydraulic oil, and the second setting unit is configured to control the control valve when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. Is kept below the switching opening.
The hydraulic system of the work machine includes a measuring device that measures the temperature of the hydraulic oil, and the third setting unit is configured to perform the first setting when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. The maximum value of the pilot pressure output from the operation valve is kept below the switching pressure at which the control valve is switched by setting the pressure of the hydraulic oil of the working valve to a predetermined value.

The hydraulic system of the working machine includes a measuring device that measures the temperature of the hydraulic oil, and the fourth setting unit is configured to perform the first setting when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. By setting the pressure of the hydraulic oil of the operating valve to a predetermined value, the maximum value of the pilot pressure output from the operation valve is kept below the operating pressure at which the hydraulic device operates.
The hydraulic system of the working machine includes a measurement device that measures the temperature of the hydraulic oil, and the fifth setting unit is configured to perform the second measurement when the temperature measured by the measurement device is equal to or lower than a predetermined temperature. The pressure of the hydraulic oil by the operating valve is kept below the operating pressure at which the hydraulic device operates.

Further, when the operation member is not operated, the first setting unit maintains a pilot pressure applied to the control valve below the switching pressure, and the operation member is operated. The pilot pressure to be applied to the control valve is set to a pressure corresponding to the operation of the operation member.
Further, when the operation member is not operated, the second setting unit maintains the opening degree of the control valve below the switching opening degree and the operation member is operated. The opening degree of the control valve is set to an opening degree corresponding to the operation of the operation member.

The hydraulic system of the work machine includes a switch for setting whether to permit switching of the control valve, and the third setting unit is not permitted to switch the control valve and operates the operation member. Is not performed, the maximum value of the pilot pressure is kept below the switching pressure by setting the pressure of the hydraulic oil of the first operating valve to a predetermined value, and switching of the control valve is permitted. In this case, the maximum value of the pilot pressure is maintained at the switching pressure or higher.

When the operation member is not operated, the fourth setting unit holds the hydraulic oil pressure of the first operating valve at a predetermined value to keep the hydraulic pressure below the operating pressure at which the hydraulic device operates. When the operation member is operated, the operating pressure is maintained to be equal to or higher than the operating pressure at which the hydraulic device is operated.
When the operation member is not operated, the fifth setting unit holds the hydraulic oil pressure of the second operating valve at a predetermined value to keep the hydraulic pressure below the operating pressure at which the hydraulic device operates. When the operation member is operated, the operating pressure is maintained to be equal to or higher than the operating pressure at which the hydraulic device is operated.

  According to the present invention, warm-up can be easily performed.

1 is a schematic diagram of a traveling hydraulic system in a first embodiment. It is the schematic of the working system hydraulic system in 1st Embodiment. It is the figure which showed the relationship between the pilot pressure which acts on the pressure receiving part of a 3rd control valve, and switching of a 3rd control valve. It is a figure which shows the modification of the working system hydraulic system in 1st Embodiment. A part of traveling hydraulic system in a 2nd embodiment is shown. It is the figure which showed the relationship between the opening degree of a traveling control valve, and switching of a traveling control valve. It is a figure which shows the modification of the working system hydraulic system in 2nd Embodiment. It is a figure which shows a part of traveling system hydraulic system in 3rd Embodiment. It is a figure which shows the working system hydraulic system in 4th Embodiment. It is a figure which shows a part of work type | system | group hydraulic system in 5th Embodiment. It is a figure which shows a part of work type | system | group hydraulic system in 6th Embodiment. It is a figure which shows the modification of the working system hydraulic system in 6th Embodiment. It is a figure which shows the working type hydraulic system in 7th Embodiment. It is a figure which shows the work type | system | group hydraulic system in 8th Embodiment. It is a side view which shows the track loader which is an example of the working machine which concerns on this invention. It is a side view which shows a part of track loader of the state which raised the cabin.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 15 shows a side view of the working machine according to the present invention. In FIG. 15, a compact truck loader is shown as an example of a working machine. However, the working machine according to the present invention is not limited to a compact truck loader, and may be another type of loader working machine such as a skid steer loader. Moreover, a working machine other than the loader working machine may be used.

  As shown in FIGS. 15 and 16, the work machine 1 includes a machine body 2, a cabin 3, a work device 4, and a traveling device 5. In the embodiment of the present invention, the front side (left side in FIG. 15) of the driver seated on the driver's seat 8 of the work machine 1 is front, the rear side (right side in FIG. 15) is rearward, and the left side of the driver (FIG. 15). 15 on the left side and the right side of the driver (the back side in FIG. 15) as the right side. The horizontal direction, which is a direction orthogonal to the front-rear direction, will be described as the body width direction. The direction from the central part of the airframe 2 toward the right part or the left part will be described as the outside of the airframe. In other words, the outward direction of the body is the direction of the body width and away from the body 2. The direction opposite to the outside of the aircraft will be described as the inside of the aircraft. In other words, the in-machine direction is the width direction of the machine body and the direction approaching the machine body 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 attached to the machine body 2. The traveling device 5 is provided outside the airframe 2. A prime mover is mounted at the rear of the body 2.
The work device 4 includes a boom 10, a work tool 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

  The boom 10 is provided on the right and left sides of the cabin 3 so as to be swingable up and down. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip (front end) of the boom 10 so as to be swingable up and down. The lift link 12 and the control link 13 support the base part (rear part) 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 front portions of the left and right booms 10 are connected to each other by a deformed connection pipe. The bases (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 side and the right side of the body 2 corresponding to the left and right booms 10.
The lift link 12 is provided in the longitudinal direction at the rear of the base of each boom 10. The upper portion (one end side) of the lift link 12 is pivotally supported around the horizontal axis via a pivot shaft 16 (first pivot shaft) near the rear portion of the base of each boom 10. Further, the lower portion (the other end side) of the lift link 12 is pivotally supported around the horizontal axis via a pivot shaft 17 (second pivot shaft) near the rear portion of the machine body 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

  The upper part of the boom cylinder 14 is pivotally supported about a horizontal axis via a pivot shaft 18 (third pivot shaft). The third pivot shaft 18 is a base portion of each boom 10 and is provided at the front portion of the base portion. The lower part of the boom cylinder 14 is pivotally supported around a horizontal axis via a pivot shaft 19 (fourth pivot shaft). The fourth pivot shaft 19 is provided near the lower part of the rear part of the machine body 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 pivotally supported about a horizontal axis via a pivot shaft 20 (fifth pivot shaft). The fifth pivot shaft 20 is the body 2 and is provided at a position corresponding to the front of the lift link 12. The other end of the control link 13 is pivotally supported about a horizontal axis via a pivot shaft 21 (sixth pivot shaft). 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.

  By expanding and contracting the boom cylinder 14, 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, and the tip of each boom 10 is Goes up and down. The control link 13 swings up and down around the fifth pivot shaft 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the second pivot shaft 17 as the control link 13 swings up and down.

Another work tool can be attached to the front portion of the boom 10 instead of the bucket 11. Another working tool is an attachment (preliminary attachment) such as a hydraulic crusher, a hydraulic breaker, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, and a snow blower.
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 equipment equipped in the preliminary attachment to the first pipe material such as a pipe provided in the boom 10. Specifically, the first pipe member can be connected to one end of the connecting member 50, and the second pipe member connected to the hydraulic device of the preliminary attachment can be connected to the other end. Thereby, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The bucket cylinder 15 is arranged near the front part of each boom 10. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
Each of the left and right traveling devices 5 is a crawler type (including a semi-crawler type) traveling device in this embodiment. In addition, you may employ | adopt the wheel type traveling apparatus which has a front wheel and a rear wheel.

Next, a hydraulic system for a working machine according to the present invention will be described.
As shown in FIGS. 1 and 2, the hydraulic system can be roughly divided into a traveling hydraulic system 30A and a working hydraulic system 30B.
The traveling hydraulic system 30A will be described.
As shown in FIG. 1, the traveling system hydraulic system 30A is a system that mainly drives a left traveling motor device (first traveling motor device) 31L and a right traveling motor device (second traveling motor device) 31R. . The traveling system hydraulic system 30A includes a prime mover 32, a direction switching valve 33, a first hydraulic pump P1, a first traveling motor device 31L, a second traveling motor device 31R, and a hydraulic device 34. .

  The prime mover 32 includes an electric motor, an engine, and the like. In this embodiment, the prime mover 32 is an engine. The first hydraulic pump P1 is a pump that is driven by the power of the prime mover 32, and is constituted by a constant capacity type gear pump. The first hydraulic pump P1 can discharge the hydraulic oil stored in the tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 that stores hydraulic oil may be referred to as a hydraulic oil tank. Of the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be called pilot oil, and the pressure of the pilot oil may be called pilot pressure.

  A discharge oil passage (fifth oil passage) 40 through which hydraulic oil (pilot oil) flows is provided on the discharge side of the first hydraulic pump P1. The discharge oil passage 40 is provided with a filter 35, a direction switching valve 33, a first travel motor device 31L, and a second travel motor device 31R. A charge oil passage 41 branched from the discharge oil passage 40 is provided between the filter 35 and the direction switching valve 33. The charge oil passage 41 reaches the hydraulic device 34.

The direction switching valve 33 is an electromagnetic valve that changes the rotation of the first traveling motor device 31L and the second traveling motor device 31R, and is a two-position switching valve that can be switched between the first position 33a and the second position 33b by excitation. It is. The switching operation of the direction switching valve 33 is performed by an operation member (not shown).
The first travel motor device 31L is a motor that transmits 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 31 </ b> R is a motor that transmits power to the drive shaft of the travel device provided on the right side of the body 2.

The first traveling motor device 31L includes an HST motor (traveling motor) 36, a swash plate switching cylinder 37, and a traveling control valve (hydraulic switching valve) 38A. The HST motor 36 is a swash plate type variable capacity axial motor that can change the vehicle speed (rotation) to the first speed or the second speed.
The swash plate switching cylinder 37 is a cylinder that changes the angle of the swash plate of the HST motor 36 by expansion and contraction. The travel control valve 38A is a valve that expands and contracts the swash plate switching cylinder 37 to one side or the other side, and is a two-position switching valve that switches between the first position 38a and the second position 38b. The switching operation of the travel control valve 38A is performed by the direction switching valve 33 located on the upstream side connected to the travel control valve 38A.

  As described above, according to the first travel motor device 31L, when the direction switching valve 33 is set to the first position 33a by the operation of the operation member, the pilot oil is drained in the section between the direction switching valve 33 and the travel control valve 38A. The travel control valve 38A is switched to the first position 38a. As a result, the swash plate switching cylinder 37 contracts and the HST motor 36 enters the first speed state. When the direction switching valve 33 is set to the second position 33b by operating the operation member, the pilot oil is supplied to the traveling control valve 38A through the direction switching valve 33, and the traveling control valve 38A is switched to the second position 38b. As a result, the swash plate switching cylinder 37 extends and the HST motor 36 enters the second speed state.

The second traveling motor device 31R operates in the same manner as the first traveling motor device 31L. Since the configuration and operation of the second traveling motor device 31R are the same as those of the first traveling motor device 31L, description thereof is omitted.
The hydraulic device 34 is a device that 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 motor. And a drive circuit (right drive circuit) 34R for driving the device 31R.

  The drive circuits 34L and 34R each have an HST pump (travel hydraulic pump) 53, speed change oil passages 57h and 57i, and a second charge oil passage 57j. The speed change oil passages 57 h and 57 i are oil passages for connecting the HST pump 53 and the HST motor 36. The second charge oil passage 57j is an oil passage that 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 HST pump 53 is a swash plate type variable displacement axial pump driven by the power of the prime mover 32. The HST pump 53 has a forward pressure receiving portion 53a and a reverse pressure receiving portion 53b on which pilot pressure acts, and the angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 53a and 53b. By changing the angle of the swash plate, the output of the HST pump 53 (discharge amount of hydraulic oil) and the discharge direction of hydraulic oil can be changed.

  The change of the output of the HST pump 53 and the discharge direction of the hydraulic oil can be performed by a travel lever 54 provided around the driver's seat 8. The travel lever 54 is supported so as to be tiltable from the neutral position in an oblique direction between front and rear, left and right and front and rear, right and left. A discharge oil passage (fifth oil passage) 40 is connected to the travel lever 54, and hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied. By tilting the travel lever 54, a pilot valve (operation valve) 55 provided at the lower portion of the travel lever 54 can be operated.

  When the traveling lever 54 is tilted forward, the forward pilot valve 55A is operated, and pilot pressure is output from the forward pilot valve 55A. This pilot pressure acts on the forward pressure receiver 53a of the left drive circuit 34L and the forward pressure receiver 53a of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 rotates forward (forward rotation) at a speed proportional to the tilting amount of the travel lever 54, and the work implement 1 moves straight forward.

  Further, when the traveling lever 54 is tilted rearward, the reverse pilot valve 55B is operated, and the pilot pressure is output from the reverse pilot valve 55B. The pilot pressure acts on the reverse pressure receiving portion 53b for the reverse drive of the left drive circuit 34L and the reverse pressure reception portion 53b for the reverse drive of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 reverses (reversely rotates) at a speed proportional to the tilting amount of the travel lever 54, and the work implement 1 moves straight backward.

  Further, when the traveling lever 54 is tilted to the right, the right turning pilot valve 55C is operated, and the pilot pressure is output from the right turning pilot valve 55C. This pilot pressure also acts on the forward pressure receiver 53a of the left drive circuit 34L and the reverse pressure receiver 53b of the right drive circuit 34R. As a result, the output shaft of the left HST motor 36 rotates in the forward direction and the output shaft of the right HST motor 36 rotates in the reverse direction, so that the work implement 1 turns to the right.

  When the traveling lever 54 is tilted forward, the forward pilot valve 55A is operated, and pilot pressure is output from the forward pilot valve 55A. This pilot pressure acts on the forward pressure receiver 53a of the left drive circuit 34L and the forward pressure receiver 53a of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 rotates forward (forward rotation) at a speed proportional to the tilting amount of the travel lever 54, and the work implement 1 moves straight forward.

  Further, when the traveling lever 54 is tilted rearward, the reverse pilot valve 55B is operated, and the pilot pressure is output from the reverse pilot valve 55B. The pilot pressure acts on the reverse pressure receiving portion 53b for the reverse drive of the left drive circuit 34L and the reverse pressure reception portion 53b for the reverse drive of the right drive circuit 34R. As a result, the output shaft of the HST motor 36 reverses (reversely rotates) at a speed proportional to the tilting amount of the travel lever 54, and the work implement 1 moves straight backward.

  Further, when the traveling lever 54 is tilted to the right, the right turning pilot valve 55C is operated, and the pilot pressure is output from the right turning pilot valve 55C. This pilot pressure also acts on the forward pressure receiver 53a of the left drive circuit 34L and the reverse pressure receiver 53b of the right drive circuit 34R. As a result, the output shaft of the left HST motor 36 rotates in the forward direction and the output shaft of the right HST motor 36 rotates in the reverse direction, so that the work implement 1 turns to the right.

  Further, when the traveling lever 54 is tilted to the left, the left turning pilot valve 55D is operated, and the pilot pressure is output from the left turning pilot valve 55D. This pilot pressure also acts on the forward pressure receiver 53a of the right drive circuit 34R and the reverse pressure receiver 53b of the left drive circuit 34L. As a result, the output shaft of the right HST motor 36 rotates in the forward direction and the output shaft of the left HST motor 36 rotates in the reverse direction, so that the work implement 1 turns to the left.

Further, when the traveling lever 54 is tilted in the oblique direction, the rotation direction and rotation of the output shaft of the HST motor 36 are caused by the differential pressure between the pilot pressures acting on the forward pressure receiving portion 53a and the reverse pressure receiving portion 53b of each drive circuit. The speed is determined, and the work implement turns right or left while moving forward or backward.
The working hydraulic system 30B will be described.

As shown in FIG. 2, the working system hydraulic system 30B is a system for operating the boom 10, the bucket 11, a spare attachment, and the like, and includes a plurality of control valves 56 and a working system hydraulic pump (second hydraulic pump) P2. I have.
The second hydraulic pump P2 is a pump installed at a position different from the first hydraulic pump P1, and is constituted by a constant capacity type gear pump. The second hydraulic pump P <b> 2 can discharge the hydraulic oil stored in the hydraulic oil tank 22. In particular, the second hydraulic pump P2 mainly discharges hydraulic oil that operates the hydraulic actuator.

  A main oil passage (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. The control valve 56 is a valve capable of controlling the hydraulic equipment. The hydraulic device is a device for controlling (driving) a hydraulic device such as a boom, bucket, hydraulic crusher, hydraulic breaker, angle bloom, earth auger, pallet fork, sweeper, mower, snow blower, for example, Hydraulic cylinders, hydraulic motors, etc.

  As shown in FIG. 2, 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 the boom. The second control valve 56B is a valve that controls a hydraulic cylinder (bucket cylinder) 15 that controls the bucket. The third control valve 56C is a valve that controls hydraulic equipment (hydraulic cylinder, hydraulic motor) mounted on a spare attachment such as a hydraulic crusher, a hydraulic breaker, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, and a snow blower. is there.

The first control valve 56A and the second control valve 56B are pilot-type direct acting spool type three-position switching valves, respectively. The first control valve 56A and the second control valve 56B are switched to the neutral position, the first position different from the neutral position, the neutral position, and the second position different from the first position by the pilot pressure.
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.

  The operation of the boom 10 and the bucket 11 can be performed by an operation lever 58 provided around the driver's seat 8. The operation lever 58 is supported so as to be tiltable in the front-rear, left-right, and diagonal directions from the neutral position. By tilting the operation lever 58, a plurality of pilot valves (operation valves) 59A, 59B, 59C, 59D provided under the operation lever 58 can be operated. The pilot valves 59A, 59B, 59C, 59D and the first hydraulic pump P1 are connected by a discharge oil passage (fifth oil passage) 40. The pilot valves 59A, 59B, 59C, and 59D have discharge ports (ports) that are connected to the hydraulic oil tank 22 and are connected to the hydraulic oil tank 22 via the discharge oil passage 42.

  The plurality of pilot valves (operating valves) 59A, 59B, 59C, 59D and the plurality of control valves 56 are connected to each other by a plurality of oil passages (sixth oil passages) 43a, 43b, 43c, 43d. Specifically, the pilot valve 59A is connected to the first control valve 56A via the sixth oil passage 43a. The pilot valve 59B is connected to the first control valve 56A via the sixth oil passage 43b. The pilot valve 59C is connected to the first control valve 56B via the sixth oil passage 43c. The pilot valve 59D is connected to the first control valve 56B via the sixth oil passage 43d. The pilot valve (operating valve) 59A, 59B, 59C, 59D can set the pressure of the hydraulic oil output according to the operation of the operating lever 58, respectively.

Specifically, when the operation lever 58 is tilted forward, the descending pilot valve (operating valve) 59A is operated, and the pilot pressure of the pilot oil output from the descending pilot valve 59A is set. This 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 operation lever 58 is tilted rearward, the ascending pilot valve (operating valve) 59B is operated, and the pilot pressure of the pilot oil output from the ascending pilot valve 59B is set. This pilot pressure acts on the pressure receiving portion of the first control valve 56A, the boom cylinder 14 extends, and the boom 10 rises.

When the operation lever 58 is tilted to the right side, the bucket dump pilot valve (operating 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 extends, and the bucket 11 performs a dumping operation.
When the operating lever 58 is tilted to the left, the bucket squeeze pilot valve (operating 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, the bucket cylinder 15 contracts, and the bucket 11 performs a squeeze operation.

  The third control valve 56C is a pilot type direct acting spool type three-position switching valve. The third control valve 56C is switched to the first position 62a, the second position 62b, and the third position (neutral position) 62c by the pilot pressure. That is, the third control valve 56C controls the direction, flow rate, and pressure of the hydraulic oil toward the hydraulic equipment of the preliminary attachment by switching to the first position 62a, the second position 62b, and the third position 62c.

A supply / discharge oil passage 83 is connected to the third control valve 56C. One end of the supply / discharge oil passage 83 is connected to the supply / discharge port of the third control valve 56C, a middle portion of the supply / discharge oil passage 83 is connected to the connection member 50, and the other end of the supply / discharge oil passage 83 is Connected to the hydraulic equipment of the spare attachment. The supply / discharge oil passage 83 is configured by the first pipe material and the second pipe material described above.
Specifically, the supply / discharge oil passage 83 includes a first supply / discharge oil passage 83 a that connects the first supply / discharge port of the third control valve 56 </ b> C and the first port of the connection member 50. Further, the supply / discharge oil passage 83 includes a second supply / discharge oil passage 83b that connects the second supply / discharge port of the third control valve 56C and the second port of the connecting 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.

  The third control valve 56C is operated by a plurality of proportional valves 60. The proportional valve 60 is an electromagnetic valve whose opening degree can be changed by excitation. The plurality of proportional valves 60 are a first proportional valve 60A and a second proportional valve 60B. A discharge oil passage 40 is connected to the first proportional valve 60A and the second proportional valve 60B. The first proportional valve 60A and the second proportional valve 60B are supplied from the first hydraulic pump P1 with pilot oil which is hydraulic oil used for control among hydraulic oil.

The third control valve 56C and the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B) are connected by a first oil passage 86.
The first oil passage 86 is an oil passage through which pilot oil flows to the third control valve 56C via the proportional valves 60 (the first proportional valve 60A and the second proportional valve 60B). The first oil passage 86 is composed of a steel pipe, a pipe, a hose, and the like. The first oil passage 86 includes a first control oil passage 86a that connects the first proportional valve 60A and the pressure receiving portion 61a of the third control valve 56C, and a pressure receiving portion 61b of the second proportional valve 60B and the third control valve 56C. And a second control oil passage 86b for connecting the two.

  Accordingly, when the first proportional valve 60A is opened, the pilot oil acts on the pressure receiving portion 61a of the third control valve 56C via the first control oil passage 86a, and the pressure of the first proportional valve 60A reaches the pressure receiving portion 61a. The pilot pressure to be applied (acted) is determined. When the pilot pressure applied to the pressure receiving portion 61a exceeds a predetermined value, the third control valve 56C is switched from the third position (neutral position) 62c to the first position 62a by the movement of the spool. When the second proportional valve 60B is opened, the pilot oil acts on the pressure receiving portion 61b of the third control valve 56C via the second control oil path 86b, and the pressure of the second proportional valve 60B is changed to the pressure receiving portion 61b. The pilot pressure to be applied (acted) is determined. When the pilot pressure applied to the pressure receiving portion 61b becomes a predetermined value or more, the third control valve 56C is switched from the third position (neutral position) 62c to the second position 62b by the movement of the spool.

  A second oil passage 87 is connected to the first oil passage 86. The second oil passage 87 is an oil passage connecting the first oil passage 86 and the hydraulic oil tank (tank) 22. That is, the second oil passage 87 is an oil passage connecting the hydraulic oil tank 22 and the third control valve 56C and the proportional valve 60. Specifically, the second oil passage 87 includes a first discharge oil passage 87a that connects the first control oil passage 86a and the hydraulic oil tank 22, and a second oil passage that connects the second control oil passage 86b and the hydraulic oil tank 22. And a discharge oil passage 87b. Further, the second oil passage 87 is provided with a throttle portion 88 that reduces the flow rate of the hydraulic oil flowing through the second oil passage 87. The throttle portion 88 includes a first throttle portion 88a provided in the first control oil passage 86a and a second throttle portion 88b provided in the second control oil passage 86b.

  Excitation of the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B) is performed by the control device 90. The control device 90 is composed of a CPU and the like. The control device 90 includes a first setting unit 91 and a storage unit 92. The first setting unit 91 includes a program, an electric / electronic circuit, and the like incorporated in the control device 90. The first setting unit 91 sets the opening degree of the proportional valve 60 by performing predetermined excitation on the proportional valve 60.

An operation member 93 is connected to the control device 90. An operation amount (for example, a slide amount, a swing amount, etc.) of the operation member 93 is input to the control device 90. The operation member 93 is composed of, for example, a swingable seesaw type switch, a slide type switch that can slide, or a push type switch that can be pressed.
Hereinafter, the third control valve 56C, the proportional valve 60, the control device 90, the first setting unit 91, the storage unit 92, the operation member 93, and the like will be described in detail.

FIG. 3 is a diagram showing the relationship between the pilot pressure acting on the pressure receiving portions 61a and 61b of the third control valve 56C and the switching of the third control valve 56C.
As shown in FIG. 3, for example, if the pilot pressure acting on the pressure receiving portion 61a of the third control valve 56C is less than the boundary pressure (switching pressure) A1 for switching from the neutral position 62c to the first position 62a, the third The control valve 56C remains in the neutral position 62c.

  Here, the first setting unit 91 of the control device 90 sets the pilot pressure applied to the third control valve 56C to a pressure lower than the switching pressure A1 when the operation member 93 is not operated (the operation amount is zero). Can be set. Specifically, the first setting unit 91 performs control to apply a predetermined pilot pressure (referred to as a first pressurization pressure B1) to the pressure receiving unit 61a of the third control valve 56C in a state where the operation member 93 is not operated. The first pressurization pressure B1 is not less than zero and less than the switching pressure A1 (0 <B1 <A1). That is, the first setting unit 91 sets the opening of the first proportional valve 60A so that the pilot pressure acting on the pressure receiving unit 61a becomes the first pressurization pressure B1. In other words, the first setting unit 91 sets the pilot pressure in the first control oil passage 86a to be greater than or equal to zero and less than the switching pressure A1.

For example, the storage unit 92 of the control device 90 stores an opening degree (first switching opening degree) of the first proportional valve 60A at the switching pressure A1, or a current value corresponding to the first switching opening degree. Yes. The first setting unit 91 applies a predetermined current to the solenoid 60a of the first proportional valve 60A, thereby maintaining the opening of the first proportional valve 60A at zero or more and less than the first switching opening.
Similarly, if the pilot pressure acting on the pressure receiving portion 61b of the third control valve 56C is lower than the boundary pressure (switching pressure) A2 for switching from the neutral position 62c to the second position 62b, the third control valve 56C. Remains at the third position 62c. The first setting unit 91 performs control to apply a predetermined pilot pressure (referred to as a second pressurization pressure B2) to the pressure receiving unit 61b of the third control valve 56C in a state where the operation member 93 is not operated. The second pressurization pressure B2 is not less than zero and less than the switching pressure A2 (0 <B2 <P2). That is, the 1st setting part 91 sets the opening degree of the 2nd proportional valve 60B so that the pilot pressure which acts on the pressure receiving part 61b may turn into 2nd pressurization B2. In other words, the first setting unit 91 sets the pilot pressure in the second control oil passage 86b to be greater than or equal to zero and less than the switching pressure A2.

For example, the storage unit 92 of the control device 90 stores an opening degree (second switching opening degree) of the second proportional valve 60B at the switching pressure A2 or a current value corresponding to the second switching opening degree. Yes. The first setting unit 91 applies a predetermined current to the solenoid of the second proportional valve 60B, thereby holding the opening of the second proportional valve 60B at zero or more and less than the second switching opening.
In this embodiment, the switching pressure A1 and the switching pressure A2 are the same value, but may be different values. The switching pressure A1 and the switching pressure A2 can be set by a spring (a spring that attempts to return the spool that moves with the pilot pressure to the neutral position) provided in the third control valve 56C.

  As mentioned above, according to the 1st setting part 91, the pilot pressure which acts on the pressure receiving part of the 3rd control valve 56C is hold | maintained less than switching pressure A1, A2. Therefore, pilot oil flows from the proportional valve 60 (first proportional valve 60A, second proportional valve 60B) to the first oil passage 86 (first control oil passage 86a, second control oil passage 86b). The oil flows from the first oil passage 86 to the second oil passage 87 (first exhaust oil passage 87a, second exhaust oil passage 87b) and returns to the hydraulic oil tank 22. That is, in a state where the hydraulic equipment is not operated (a state where the third control valve 56C is held in the neutral position), the hydraulic oil in the hydraulic oil tank 22 is supplied to the first pump P1, the discharge oil passage 40, the proportional valve 60, the first It can circulate through the 1 oil path 86 and the 2nd oil path 87, and can raise the temperature of hydraulic fluid by circulation. In other words, the hydraulic system can be warmed up.

  Note that the control (the adjustment control of the proportional valve 60) for applying the first pressurization pressure B1 and the second pressurization pressure B2 by the first setting unit 91 may be alternately performed between the first proportional valve 60A and the second proportional valve 60B. Good. For example, the first setting unit 91 stops the opening degree control for the first proportional valve 60A after holding the opening degree of the first proportional valve 60A for a predetermined time at zero or more and less than the first switching opening degree, Opening control is started to hold the opening of the second proportional valve 60B at a predetermined time or more and less than the second switching opening for a predetermined time.

On the other hand, when the operation member 93 is operated (the operation amount is not zero), a current corresponding to the operation amount of the operation member 93 is supplied to the solenoid 60a of the first proportional valve 60A or the solenoid 60b of the second proportional valve 60B. Apply to. That is, the opening degree of the first proportional valve 60 </ b> A and the second proportional valve 60 </ b> B is changed according to the operation amount of the operation member 93.
For example, as a result of adjusting the opening degree of the first proportional valve 60A by swinging or sliding the operation member 93 in one direction, if the pilot pressure of the pressure receiving portion 61a becomes equal to or higher than the switching pressure, the third control valve 56C. The third control valve 56C is switched to the first position 62a. Further, for example, when the pilot pressure of the pressure receiving portion 61b becomes equal to or higher than the switching pressure as a result of adjusting the opening of the second proportional valve 60A by swinging or sliding the operation member 93 in the other direction, the third control is performed. The spool of the valve 56C moves and the third control valve 56C switches to the second position 62b.

  FIG. 4 is a diagram illustrating a modified example of the work system hydraulic system in the first embodiment. As shown in FIG. 4, the working system hydraulic system 30 </ b> B includes a measuring device 95 that measures the temperature of the hydraulic oil. The measuring device 95 is provided, for example, in the hydraulic oil tank 22, on the inlet side of the main oil passage 39, the discharge oil passage 40, or the proportional valve 60. The temperature measured by the measuring device 95 is input to the control device 90.

The first setting unit 90 uses the pilot pressure of the third control valve 56C as a pilot pressure to be applied to the third control valve 56C when the temperature of the measuring device 95 acquired by the control device 90 is equal to or lower than a predetermined temperature. Hold at a pressure lower than the pressure. For example, when the operating member 93 is not operated and the temperature measured by the measuring device 95 is 0 ° C. or less, the opening of the first proportional valve 60A is maintained at zero or more and less than the first switching opening. The opening of the second proportional valve 60B is maintained at zero or more and less than the second switching opening. When the temperature measured by the measuring device 95 exceeds 10 ° C., the opening degree control of the proportional valve 60 is stopped. In addition, it is preferable that the 1st setting part 90 sets the opening degree (pilot pressure provided to the 3rd control valve 56C) of the proportional valve 60 according to the temperature measured with the measuring apparatus 95. FIG. Specifically, as the temperature measured by the measuring device 95 is lower, the first setting unit 90 increases the opening of the first proportional valve 60A (increases the applied pressure), and the temperature measured by the measuring device 95 is larger. Accordingly, the opening of the first proportional valve 60A is reduced (the pressure to be applied is reduced). For example, when the temperature is −20 ° C., the first setting unit 90 sets the pilot pressure applied to the third control valve 56C to 0.3 MPa, and when the temperature is −10 ° C., the first setting unit 90 sets the pilot pressure applied to the third control valve 56C to 0. Set to 2 MPa.
[Second Embodiment]
FIG. 5 shows a part of the traveling hydraulic system in the second embodiment. FIG. 5 shows a circuit in which the travel control valve 38A shown in the first embodiment is changed to another travel switching valve 38B in the travel system hydraulic system 30A. In the second embodiment, a configuration different from the first embodiment will be described.

  As shown in FIG. 5, the travel control valve 38B is configured by an electromagnetic three-position switching valve that switches to a first position 38a, a second position 38b, and a third position (neutral position) 38c. That is, the travel control valve 38A expands and contracts the swash plate switching cylinder 37, which is a hydraulic device, to one side or the other side by switching to the first position 38a, the second position 38b, and the third position (neutral position) 38c. .

A discharge oil passage 40 and a third oil passage (supply / discharge oil passage) 100 are connected to the travel control valve 38B. The third oil passage 100 is an oil passage that connects the travel control valve 38 </ b> B and the swash plate switching cylinder 37.
The third oil passage 100 includes a first supply / discharge oil passage 100 a that connects the first supply / discharge port of the travel control valve 38 </ b> B and the first port (bottom port) of the swash plate switching cylinder 37. The third oil passage 100 includes a second supply / discharge oil passage 100b that connects the second supply / discharge port of the travel control valve 38B and the second port (rod port) of the swash plate switching cylinder 37. That is, by operating the travel control valve 38B, hydraulic fluid flows from the travel control valve 38B toward the first supply / discharge oil passage 100a, or from the travel control valve 38B toward the second supply / discharge oil passage 100b. Can flow.

A fourth oil passage 101 is connected to the third oil passage 100. The fourth oil passage 101 is an oil passage connecting the third oil passage 100 and the hydraulic oil tank (tank) 22. That is, the fourth oil passage 101 is an oil passage that connects the hydraulic oil tank 22 between the travel control valve 38 </ b> B and the swash plate switching cylinder 37.
Specifically, the fourth oil passage 101 connects the first discharge oil passage 101a connecting the first supply / discharge oil passage 100a and the hydraulic oil tank 22, and the second supply / discharge oil passage 100b and the hydraulic oil tank 22. 2nd discharge oil path 101b. The fourth oil passage 101 is provided with a throttle portion 102 that reduces the flow rate of the hydraulic oil flowing through the fourth oil passage 101. The throttle unit 102 includes a first throttle unit 102a provided in the first supply / discharge oil passage 100a and a second throttle unit 102b provided in the second supply / discharge oil passage 100b.

  Excitation of the travel control valve 38B is performed by the control device 105. The control device 105 is composed of a CPU and the like. The control device 105 includes a second setting unit 106 and a storage unit 107. The second setting unit 106 includes a program, an electric / electronic circuit, and the like incorporated in the control device 105. The second setting unit 106 sets the opening of the travel control valve 38B by performing predetermined excitation on the travel control valve 38B.

An operation member 108 is connected to the control device 105. An operation amount (for example, a slide amount, a swing amount, etc.) of the operation member 108 is input to the control device 105. The operation member 108 is constituted by, for example, a swingable seesaw type switch, a slidable slide type switch, or a pushable push type switch.
Hereinafter, the travel control valve 38B, the travel control valve 38B, the control device 105, the second setting unit 106, the storage unit 107, the operation member 108, and the like will be described in detail.

The second setting unit 106 of the control device 105 can set the opening degree of the travel control valve 38B to be less than the switching opening degree of the travel control valve 38B when the operation member 108 is not operated (the operation amount is zero). It is.
FIG. 6 is a diagram showing the relationship between the opening degree of the travel control valve 38B and switching of the travel control valve 38B.

  As shown in FIG. 6, for example, if the opening degree of the travel control valve 38B is less than the opening degree (first switching opening degree) M1 of the boundary for switching from the neutral position 38c to the first position 38a, the travel control valve 38B is It remains in the neutral position 38c. Here, the smallest opening when the hydraulic oil passes through the travel control valve 38B from the discharge oil passage 40 and flows into the first supply / discharge oil passage 100a is defined as the minimum opening M3. The second setting unit 106 sets the opening degree K1 of the travel control valve 38B to the minimum opening degree M3 or more and less than the first switching opening degree M1 when the operation member 108 is not operated (M3 ≦ K1 <M1).

For example, the storage unit 107 of the control device 105 stores a first switching opening M1 (a current value corresponding to the first switching opening M1) and a minimum opening M3. The second setting unit 106 applies the predetermined current to the solenoid of the travel control valve 38B when the operation amount of the operation member 108 is zero, thereby setting the opening K1 of the travel control valve 38A to be equal to or greater than the minimum opening M3. It is kept below the first switching opening M1.
If the opening degree of the travel control valve 38B is less than the opening degree (second switching opening degree) M2 at the boundary for switching from the neutral position 38c to the second position 38b, the travel control valve 38B remains at the neutral position 38c. . The second setting unit 106 sets the opening K2 of the travel control valve 38B to the minimum opening M3 or more and less than the second switching opening M2 when the operation member 108 is not operated (M3 ≦ K1 <M2).

For example, the storage unit 107 of the control device 105 stores the second switching opening M2 (current value corresponding to the second switching opening M2) and the minimum opening M3. When the operation amount of the operation member 108 is zero, the second setting unit 106 applies a predetermined current to the solenoid of the travel control valve 38B, thereby setting the opening K2 of the travel control valve 38A to be equal to or greater than the minimum opening M3. It is kept below the second switching opening M2.
In this embodiment, the first switching opening M1 and the second switching opening M2 are the same value, but may be different values. Further, the first switching opening M1 and the second switching opening M2 can be set by a spring provided in the travel control valve 38B (a spring that attempts to return the spool that moves with the pilot pressure to the neutral position). is there.

  As described above, according to the second setting unit 106, the travel control valve 38B is held below the first switching opening M1 and the second switching opening M2. Therefore, pilot oil flows from the travel control valve 38B to the third oil passage 100 (first supply / discharge oil passage 100a, second supply / discharge oil passage 100b), and the pilot oil flows from the third oil passage 100 to the fourth oil passage. 101 (first exhaust oil passage 101a, second exhaust oil passage 101b) and return to the hydraulic oil tank 22. That is, in a state where the hydraulic device is not operated (a state where the third control valve 56C is held at the neutral position), the hydraulic oil in the hydraulic oil tank 22 is supplied to the first pump P1, the discharge oil passage 40, the travel control valve 38B, It can circulate through the 3rd oil path 100 and the 4th oil path 101, and can raise the temperature of hydraulic fluid by circulation. In other words, the hydraulic system can be warmed up.

  Control (running control valve) for setting the openings K1 and K2 to the minimum opening M3 or more and less than the first switching opening M1, or the minimum opening M3 or more and less than the second switching opening M2 by the second setting unit 106. 38B adjustment control) may be performed alternately. For example, the second setting unit 106 holds the opening of the travel control valve 38B below the first switching opening for a predetermined time, and then stops the opening control for the travel control valve 38B, and then the travel control valve 38B. The opening control is started so that the opening is kept below the second switching opening for a predetermined time.

On the other hand, when the operation member 108 is operated (the operation amount is not zero), a current corresponding to the operation amount of the operation member 108 is applied to the travel control valve 38B solenoid or the travel control valve 38B solenoid. That is, the travel control valve 38B has its opening degree changed according to the operation amount of the operation member 108.
For example, when the opening degree of the travel control valve 38B becomes greater than or equal to the switching opening degree by swinging or sliding the operation member 108 in one direction, the spool of the travel control valve 38B moves and the travel control valve 38B To the first position 38a. Further, for example, when the opening degree of the travel control valve 38B becomes greater than or equal to the switching opening degree by swinging or sliding the operation member 108 in the other direction, the spool of the travel control valve 38B moves and the travel control valve In 38B, the travel control valve 38B switches to the second position 38b.

  FIG. 7 is a view showing a modification of the working system hydraulic system in the second embodiment. As shown in FIG. 7, the traveling hydraulic system 30A includes a measuring device 109 that measures the temperature of the hydraulic oil. For example, the measuring device 109 is provided in any one of the hydraulic oil tank 22, the main oil passage 39, the discharge oil passage 40, and the entry side of the travel control valve 38B. The temperature measured by the measuring device 109 is input to the control device 105.

The second setting unit 106 makes the opening degree of the travel control valve 38B less than the switching opening degree when the temperature of the measuring device 109 acquired by the control device 105 is equal to or lower than a predetermined temperature. For example, when the operating member 108 is not operated and the temperature measured by the measuring device 109 is 0 ° C. or less, the opening degree of the travel control valve 38B is set to the minimum opening degree M3 or more and less than the first switching opening degree M1. Or held at a minimum opening M3 or more and less than a second switching opening M2. When the temperature measured by the measuring device 109 exceeds 10 ° C., the opening control of the travel control valve 38B is stopped. Note that the second setting unit 106 also sets the opening of the travel control valve 38B according to the temperature measured by the measuring device 109, as in the first embodiment.
[Third Embodiment]
FIG. 8 shows a part of the traveling hydraulic system in the third embodiment. The third embodiment is an example in which the traveling motor is changed, and is applicable to all the embodiments. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.

  As shown in FIG. 8, in the third embodiment, the first traveling motor device 31L and the second traveling motor device 31R are modified. The first travel motor device 31L and the second travel motor device 31R include a travel motor 236, a front / rear switching valve 235, and a travel control valve (hydraulic switching valve) 38C. The first traveling motor device 31L, the second traveling motor device 31R, the traveling motor 236, the front / rear switching valve 235, and the traveling control valve (hydraulic switching valve) 38C can be supplied with hydraulic oil.

  The travel motor 236 employs a cam motor (radial piston motor). The travel motor 236 changes the rotation and torque of the output shaft by varying the capacity (motor capacity) during operation. Specifically, the travel motor 236 includes a first motor 236A and a second motor 236B. By driving the first motor 236A and the second motor 236B, the motor capacity increases and the traveling motor 236 becomes the first speed. In addition, by driving either the first motor 236A or the second motor 236B, the motor capacity is reduced, and the traveling motor 131 becomes the second speed.

  The travel control valve 38C is a two-position switching valve that switches to the first position 38a and the second position 38b. The switching operation of the travel control valve 38C is performed by the proportional valve 237. The proportional valve 237 and the travel control valve 38C are connected by a third control oil passage (first oil passage) 286. A second oil passage 287 that connects the first oil passage 286 and the hydraulic oil tank 22 is connected to the third control oil passage 286. The second oil passage 287 is provided with a throttle portion 288 that reduces the flow rate of the hydraulic oil flowing through the second oil passage 287.

  The setting of the opening degree of the proportional valve 237 is performed by the control device 90 having the first setting unit 91. The first setting unit 91 sets the pilot pressure applied to the travel control valve 38C to a pressure lower than the switching pressure of the travel control valve 38C when the operation member is not operated (the operation amount is zero). Further, when the operating member is operated, the first setting unit 91 sets the pilot pressure applied to the travel control valve 38C to be equal to or higher than the switching pressure based on a command input to the control device 90.

As described above, also in the third embodiment, the pilot pressure applied to the travel control valve 38C is set to a pressure lower than the switching pressure of the travel control valve 38C. Therefore, pilot oil flows from the proportional valve 237 to the first oil passage 286 (third control oil passage), and the pilot oil flows from the first oil passage 286 to the second oil passage 287 and returns to the hydraulic oil tank 22. It can be warmed up.
[Fourth Embodiment]
FIG. 9 shows a working hydraulic system in the fourth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above. The symbol “X1” shown in FIG. 9 indicates the connection destination of the oil passage.

  As shown in FIG. 9, the work system hydraulic system includes a first operating valve 120 and a plurality of seventh oil passages 121a and 121b. The first operation valve 120 is connected to a midway portion of the discharge oil passage (fifth oil passage) 40. The first operating valve 120 is a valve capable of changing the pressure of the pilot oil toward the remote control valves (operation valves) 59A, 59B, 59C, 59D. The first operating valve 120 is a two-position switching valve that can be switched between a first position 120a and a second position 120b by excitation. Note that the opening degree of the first operating valve 120 at the second position 120b can be changed.

  The plurality of seventh oil passages 121a and 121b are the discharge oil passage 40, and a section 40a between the first operating valve 120 and the remote control valves (operating valves) 59A, 59B, 59C and 59D, and a plurality of sixth oils This is an oil passage that connects the passages 43a, 43b, 43c, and 43d. The seventh oil passage 121a connects the section 40a and the sixth oil passages 43a and 43c. The seventh oil passage 121b connects the section 40a and the sixth oil passages 43b and 43d. A plurality of throttle parts 124 are provided in the seventh oil passages 121a and 121b.

The control device 90 includes a third setting unit 122 and a storage unit 92. The third setting unit 122 includes a program, an electric / electronic circuit, and the like incorporated in the control device 90. Hereinafter, for convenience of explanation, the remote control valves (operating valves) 59A, 59B, 59C, and 59D are simply referred to as remote control valves and the description will be continued.
The third setting unit 122 can set the maximum value (upper limit value) of the pilot pressure output from the remote control valve below the switching pressure at which the control valve 56 is switched. Specifically, when the operation lever 58 is operated to the maximum (full stroke), the pilot pressure output from the remote control valve becomes maximum. The third setting unit 122 excites the first working valve 120 and opens the first working valve 120 so that the maximum value of the pilot pressure output from the remote control valve is less than the switching pressure of the control valve 56. As described above, the opening degree of the first operation valve 120 is set. For convenience of explanation, the maximum value of the pilot pressure output from the remote control valve (the upper limit value of the pilot pressure output from the remote control valve when the operating lever 58 is fully stroked) is referred to as the maximum pilot pressure.

The storage unit 92 switches the switching pressure at which the first control valve 56A and the second control valve 56B are switched in the state where the operation lever 58 is at a full stroke, or the opening degree (switching) of the first operating valve 120 corresponding to the switching pressure. Opening) or a current value corresponding to the switching opening is stored.
Hereinafter, the operation of the third setting unit 122 will be described in detail.
A switch 123 is connected to the control device 90. The switch 123 is an on / off switch that sets whether or not to permit the operation of the control valve 56. The operation of the switch 123 is performed, for example, by raising and lowering a lever (unload) provided around the driver's seat 8. When the lever is raised, the switch 123 is turned on, and when the lever is lowered, the switch 123 is turned off.

  Here, the third setting unit 122 is configured such that the first control valve 56A and the second control valve are in a state where the switch 123 is on (the operation of the control valve 56 is not permitted) and the operation lever 58 is not operated. The pilot pressure acting on the pressure receiving portion 56B is maintained at a pressure lower than the switching pressure. That is, the third setting unit 122 applies a predetermined current to the solenoid 120c to make the opening corresponding to the second position 120b of the first operating valve 120 larger than zero, while the opening is the switching opening. Less than. That is, the opening when the first operating valve 120 is at the second position 120b is set to be not less than the minimum opening and less than the switching opening. The minimum opening is the minimum opening through which the hydraulic oil flows into the fifth oil passage 40 (seventh oil passage 131) through the first operation valve 120 as in the above-described embodiment.

The third setting unit 122 fully opens the opening at the second position when the switch 123 is off (when the operation of the control valve 56 is not permitted) and the operation lever 58 is not operated.
As described above, according to the third setting unit 122, the maximum pilot pressure is set to be lower than the switching pressure at which the control valve 56 is switched. Therefore, when the operation lever 58 is not operated (when the operation lever 58 is in a neutral state), the hydraulic oil is discharged from the discharge oil passage 40, the seventh oil passages 121a and 121b, and the sixth oil passages 43a and 43b. , 43c, 43d, and the port of the remote control valve can flow to the discharge oil passage 42 and the hydraulic oil tank 22. Therefore, the hydraulic oil can be circulated through the discharge oil passage 40, the seventh oil passages 121a and 121b, the sixth oil passages 43a, 43b, 43c and 43d, and the remote control valve, and warming up can be easily performed.

Even in the fourth embodiment, the control valve 56 is switched to the maximum pilot pressure when a measuring device for measuring the temperature of the hydraulic oil is provided and the temperature measured by the measuring device is equal to or lower than a predetermined temperature. It may be set below the switching pressure. When the temperature measured by the measuring device is 0 ° C. or less, the third setting unit 122 holds the opening degree of the valve corresponding to the second position 120b below the switching opening degree. When the temperature measured by the measurement device exceeds 10 ° C. and the switch 123 is turned off, the third setting unit 122 fully opens the valve opening corresponding to the second position 120b. Moreover, the 3rd setting part 122 may also change the opening degree of the valve corresponding to the 2nd position 120b according to the temperature measured with the measuring apparatus similarly to embodiment mentioned above.
[Fifth Embodiment]
FIG. 10 shows a traveling hydraulic system in the fifth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.

As shown in FIG. 10, the traveling system hydraulic system includes a hydraulic device 234, a traveling lever 254, a plurality of eighth oil passages 130a and 130b, ninth oil passages 131a and 131b, and a first operating valve 120. ing. The hydraulic device 234 has the same configuration as the hydraulic device 34 shown in the first embodiment. The first operating valve 120 is an electromagnetic valve whose opening degree can be changed by excitation.
The travel lever 254 has the same structure as the travel lever 54 described above, and is provided with remote control valves 255A and 255B at the bottom. The remote control valves 255 </ b> A and 255 </ b> B have discharge ports (ports) that are connected to the hydraulic oil tank 22, and are connected to the hydraulic oil tank 22 via the discharge oil passage 42.

  The eighth oil passage 130a connects the remote control valve 255A and the pressure receiving portion 53b of the HST pump 53. The eighth oil passage 130b connects the remote control valve 255B and the pressure receiving portion 53a of the HST pump 53. A throttling part 133 a is provided between the HST pump 53 and a connection part to which the ninth oil path 131 a is connected, which is the eighth oil path 130 a. Further, the throttle portion 133b is also provided between the HST pump 53 and the connecting portion to which the ninth oil passage 131b is connected, which is the eighth oil passage 130b.

  The ninth oil passage 131a is an oil passage connecting the discharge oil passage 40 and the eighth oil passage 130a. The ninth oil passage 131b is an oil passage connecting the discharge oil passage 40 and the eighth oil passage 130b. Specifically, the ninth oil passage 131a is the discharge oil passage 40, and connects the section 40b between the first operating valve 120 and the remote control valve (operation valve) 255A and the eighth oil passage 130a. The ninth oil passage 131b connects the section 40b of the discharge oil passage 40 and the eighth oil passage 130b.

  The control device 90 includes a fourth setting unit 132 and a storage unit 92. The fourth setting unit 132 includes a program, an electric / electronic circuit, and the like incorporated in the control device 90. The storage unit 92 corresponds to the minimum opening and the minimum opening of the first operating valve 120 corresponding to the operating pressure, which corresponds to the minimum pressure at which the HST pump 53 operates, in the state where the travel lever 254 is at full stroke. The current value to be stored is stored. Hereinafter, for convenience of description, the remote control valves 255A and 255B are simply referred to as remote control valves and the description will be continued. The minimum opening is the minimum opening through which the working oil flows through the first oil valves 120a and 131b through the first working valve 120, as in the above-described embodiment.

  In the fourth setting unit 132, when the warm-up is set (for example, when a signal for warm-up is input to the control device 90 by a switch or the like), the travel lever 254 is operated. In such a state, the opening degree of the first operating valve 120 is set to an opening degree that is not less than a predetermined value (minimum opening degree) and does not reach the maximum pilot pressure. In other words, the fourth setting unit 132 sets the maximum pilot pressure (the maximum pilot pressure output from the remote control valve with the travel lever 254 at full stroke) within a range in which the maximum pilot pressure does not exceed the operating pressure at which the HST pump 53 operates. 1 Open the actuating valve 120. That is, the fourth setting unit 132 performs the first operation so that the maximum pilot pressure is less than the operating pressure of the HST pump 53 even when the first operating valve 120 is excited and the first operating valve 120 is opened. The opening degree of the valve 120 is set.

  As described above, according to the fourth setting unit 132, the maximum pilot pressure is set to a pressure lower than the operating pressure at which the hydraulic device 34 operates. Therefore, when the travel lever 254 is not operated (when the travel lever 254 is in a neutral state), the hydraulic oil is discharged from the discharge oil passage 40, the eighth oil passage 130a, the eighth oil passage 130b, and the remote control valve. It can flow to the exhaust oil passage 42 and the hydraulic oil tank 22 through the port. Therefore, the hydraulic oil can be circulated through the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve, and warming up can be easily performed.

  In the fifth embodiment, the HST pump 53 operates at the maximum pilot pressure when a measuring device for measuring the temperature of the hydraulic oil is provided and the temperature measured by the measuring device is equal to or lower than a predetermined temperature. You may set below operating pressure. When the temperature measured by the measuring device is 0 ° C. or lower, the fourth setting unit 132 holds the opening of the first operating valve 120 below the operating pressure. When the temperature measured by the measuring device exceeds 10 ° C., the fourth setting unit 132 opens the opening fully, for example. Moreover, the 4th setting part 132 may also change the opening degree of the 1st action valve 120 according to the temperature measured with the measuring apparatus similarly to embodiment mentioned above.

Further, the first operation valve 120 shown in the fifth embodiment not only warms up, but also suppresses the pressure of the hydraulic oil supplied to the remote control valve, for example, to prevent engine stall. For example, when the output of the prime mover 32 decreases due to a load such as a work system, the first operating valve 120 is adjusted according to the output of the prime mover 32. The engine stall is prevented by the control device 90. Further, since the first operating valve 120 performs unloading in the same manner as the operation lever 58 described above, it is also possible to suppress the pressure of the operating oil supplied to the remote control valve. For example, as described above, when the switch 123 is on, the opening of the first operating valve 120 is set to a predetermined value. For example, when unloading and warming up, the opening degree of the first operating valve 120 is set to the minimum opening degree or more and less than the operating pressure by the fourth setting unit 132 as described above. In addition, control of the 1st action valve 120 other than warming-up is not limited to what was mentioned above.
[Sixth Embodiment]
FIG. 11 shows a traveling hydraulic system in the sixth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.

As shown in FIG. 11, the traveling system hydraulic system includes a tenth oil passage (first bypass oil passage) 140 and a second operating valve 141. The tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130a and connects the discharge oil passage 40 and the eighth oil passage 130b. The tenth oil passage 140 is branched into two in the middle, and a second bypass oil passage 151 having a throttle portion 150 is connected to the two oil passages 140a after the branch. In one oil passage 140a after branching,
An eighth oil passage 130a is connected. An eighth oil passage 130b is connected to the other oil passage 140a after the branch. In one oil passage 140 a and the other oil passage 140 a, a check valve 152 that allows pilot oil from the HST pump 53 and blocks pilot oil toward the HST pump 53 in a section connecting the second bypass oil passage 151. Is connected. In the tenth oil passage 140, a second operating valve 141 is provided in the oil passage before branching.

The second working valve 141 can change the pressure of the working oil toward the hydraulic device 234 (HST pump 53). The second operating valve 141 is an electromagnetic valve whose opening degree can be changed by excitation.
The control device 90 includes a fifth setting unit 142 and a storage unit 92. The fifth setting unit 142 includes a program incorporated in the control device 90, an electric / electronic circuit, and the like. The storage unit 92 corresponds to the operating pressure that is the lowest pressure at which the HST pump 53 operates, the opening (switching opening) of the first operating valve 120 corresponding to the operating pressure, and the switching opening, as in the above-described embodiment. The current value to be stored is stored.

  The fifth setting unit 142 can set the pilot pressure output from the tenth oil passage 140 to less than the operating pressure at which the HST pump 53 operates. The fifth setting unit 142 causes the pilot oil to flow through the tenth oil passage 140 by setting the opening of the second operation valve 141 to such an extent that the HST pump 53 does not operate when the travel lever 254 is not operated. On the other hand, when the travel lever 254 is operated, the fifth setting unit 142 closes the second working valve 141 so that the working oil does not flow into the tenth oil passage 140.

  As described above, according to the fifth setting unit 142, in a state where the traveling lever 54 is not operated (when the traveling lever 254 is in a neutral state), the hydraulic oil is discharged to the discharge oil passage 40, the tenth oil passage 140, the first The oil can flow to the discharge oil passage 42 and the hydraulic oil tank 22 through the eight oil passages 130a, the eighth oil passage 130b, and the port of the remote control valve. Therefore, the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve can be easily warmed up.

  In the sixth embodiment as well, the measuring device for measuring the temperature of the hydraulic oil is provided, and the HST pump 53 operates at the maximum pilot pressure when the temperature measured by the measuring device is equal to or lower than a predetermined temperature. You may set below operating pressure. When the temperature measured by the measuring device is 0 ° C. or lower, the fifth setting unit 142 holds the opening of the first operating valve 120 below the operating pressure. When the temperature measured by the measuring device exceeds 10 ° C., the fifth setting unit 142 opens the opening fully, for example. Moreover, the 5th setting part 142 may also change the opening degree of the 1st action valve 120 according to the temperature measured with the measuring apparatus similarly to embodiment mentioned above.

  FIG. 12 shows a modification of the sixth embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above. As shown in FIG. 12, the traveling system hydraulic system is provided with at least two tenth oil passages (first bypass oil passages) 140. One tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130a. The other tenth oil passage 140 connects the discharge oil passage 40 and the eighth oil passage 130b. One tenth oil passage 140 and the other tenth oil passage 140 are provided with a throttle portion 151. As shown in the fifth embodiment, the operation valve 120 in the modified example is also used for anti-stall and unload, and warm-up control is not performed.

According to the modification shown in FIG. 12, when the travel lever 254 is not operated, the hydraulic oil is discharged from the discharge oil passage 40, the tenth oil passage 140, the eighth oil passage 130a, the eighth oil passage 130b, and the remote control valve. It can flow to the exhaust oil passage 42 and the hydraulic oil tank 22 through the port. Therefore, the discharge oil passage 40, the eighth oil passages 130a and 130b, and the remote control valve can be easily warmed up.
[Seventh Embodiment]
FIG. 13 shows a part of a working hydraulic system in the seventh embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.

  As shown in FIG. 13, the third control valve 56C is operated by two switching valves 160A and 160B. The switching valves 160A and 160B are two-position switching valves that can switch between the first position 160a and the second position 160b. Switching of the switching valves 160A and 160B can be switched by the control device 90. For example, based on the operation of the operating member 93 connected to the control device 90, a signal to be switched from the control device 90 is output to the switching valves 160A and 160B.

A discharge oil passage 40 is connected to one switching valve 160A and the other switching valve 160B. One switching valve 160A and the pressure receiving portion 61a of the third control valve 56C are connected by a first control oil passage 186a. The other switching valve 160B and the pressure receiving portion 61b of the third control valve 56C are connected by a second control oil path 186b.
The working system hydraulic system according to the seventh embodiment includes a third bypass oil passage 161 and a fourth bypass oil passage 162. The third bypass oil passage 161 is an oil passage connecting the inlet side of one switching valve 160A and the outlet side of one switching valve 160A, and is provided with a throttle portion 163. In other words, the third bypass oil passage 161 connects the vicinity of the input port of one switching valve 160A and the first control oil passage 186a.

The fourth bypass oil passage 162 is an oil passage connecting the inlet side of the other switching valve 160B and the outlet side of the other switching valve 160B, and is provided with a throttle portion 164. In other words, the fourth bypass oil passage 162 connects the vicinity of the input port of the other switching valve 160B and the second control oil passage 186b.
As described above, according to the seventh embodiment, in the state where the one switching valve 160a is in the first position 160a, the hydraulic oil passes through the discharge oil passage 40 and the third bypass oil passage 161 to the first control oil passage 186a. Enters, passes through one switching valve 160a, and flows to the hydraulic oil tank 22. Similarly, when the other switching valve 160b is in the first position 160b, the hydraulic oil passes through the discharge oil passage 40 and the fourth bypass oil passage 162 and enters the second control oil passage 186b, and the other switching valve 160b. And flows to the hydraulic oil tank 22. As described above, the hydraulic oil can be circulated through the discharge oil passage 40, the bypass oil passage (the third bypass oil passage 161, the fourth bypass oil passage 162), and the switching valves 160a and 160b. It can be done easily.

In the seventh embodiment, the third control valve 56C has been described. However, the third control valve 56C may be applied to other control valves 56 (first control valve 56A, second control valve 56B). The operating oil may be circulated by providing a switching valve for operating the control valve 56 and connecting the inlet side and the outlet side of the switching valve with a bypass oil passage.
[Eighth Embodiment]
FIG. 14 shows a part of a traveling hydraulic system in the eighth embodiment. The eighth embodiment is a modification of the above-described second embodiment. In addition, description is abbreviate | omitted about the structure similar to embodiment mentioned above.

  As shown in FIG. 14, the traveling system hydraulic system has a fifth bypass oil passage 170 and a sixth bypass oil passage 171. The fifth bypass oil passage 170 is an oil passage connecting the discharge oil passage 40 and the first port (bottom port) of the swash plate switching cylinder 37. That is, the fifth bypass oil passage 170 connects the discharge oil passage 40 and the first supply / discharge oil passage 100a. The fifth bypass oil passage 170 is provided with a throttle portion 172.

The sixth bypass oil passage 171 is an oil passage connecting the discharge oil passage 40 and the second port (rod port) of the swash plate switching cylinder 37. That is, the sixth bypass oil passage 171 connects the discharge oil passage 40 and the second supply / discharge oil passage 100b. The sixth bypass oil passage 171 is provided with a throttle portion 173.
As described above, according to the eighth embodiment, in the state where the travel control valve 38B is set to the third position (neutral position) 38c, the hydraulic oil passes through the discharge oil passage 40 and the fifth bypass oil passage 170 to the first supply / discharge. It enters the oil passage 100a, passes through the travel control valve 38B, and flows to the hydraulic oil tank 22. Similarly, in a state where the travel control valve 38B is in the third position (neutral position) 38c, the hydraulic oil passes through the discharge oil path 40 and the sixth bypass oil path 171 and enters the second supply / discharge oil path 100b to travel. It passes through the control valve 38B and flows to the hydraulic oil tank 22. In this way, the hydraulic oil can be circulated through the discharge oil passage 40, the bypass oil passage (the fourth bypass oil passage 170, the fifth bypass oil passage 171), and the travel control valve 38B, and warming up can be easily performed. Can be done.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Working machine 22 Tank (hydraulic oil tank)
32 prime movers 43a, 43b, 43c 43d sixth oil passage 56 control valve 55 operation valve 59 operation valve 60 proportional valve 86 first oil passage 87 second oil passage 91 first setting portion 93 operation member 95 measuring device 100 third oil passage 101 4th oil path 106 2nd setting part 121a, 121b 7th oil path 122 3rd setting part 130a, 130b 8th oil path 131a, 131b 9th oil path 132 4th setting part 142 5th setting part 140 10th oil Road

Claims (8)

A hydraulic pump that discharges hydraulic oil;
A tank for storing hydraulic oil;
Hydraulic equipment actuated by hydraulic oil,
A control valve capable of controlling the hydraulic equipment, the control valve capable of switching the flow direction of the hydraulic oil by the pilot pressure of the pilot oil which is the hydraulic oil used for control among the hydraulic oil;
A proportional valve that is supplied with the pilot oil and sets a pilot pressure of the pilot oil to be applied to the control valve;
An operation member for operating the hydraulic device by changing the opening of the proportional valve according to an operation amount;
A first oil passage connecting the proportional valve and the control valve;
A second oil passage connecting the first oil passage and the tank;
When the operation member is not operated, a pilot pressure applied to the control valve by the proportional valve can be set to a pressure lower than a switching pressure at which the control valve is switched and higher than zero . A setting section;
The working machine's hydraulic system. A hydraulic pump that discharges hydraulic oil;
A tank for storing hydraulic oil;
Hydraulic equipment actuated by hydraulic oil,
A valve capable of controlling the hydraulic device, the control valve capable of switching the flow direction of the hydraulic oil by changing the opening;
An operation member for operating the hydraulic equipment by switching the control valve when operated,
A third oil passage connecting the control valve and the hydraulic device;
A fourth oil passage connecting the third oil passage and the tank;
A second setting unit capable of setting the opening degree of the control valve to a value less than a switching opening degree where the control valve is switched and greater than zero when the operation member is not operated ;
The working machine's hydraulic system.   2. The hydraulic system for a working machine according to claim 1, further comprising a throttle portion that reduces a flow rate of the hydraulic oil flowing through the second oil passage.   The hydraulic system for a working machine according to claim 2, further comprising a throttle portion that reduces a flow rate of the working oil flowing through the fourth oil passage. A measuring device for measuring the temperature of the hydraulic oil;
The said 1st setting part hold | maintains the pilot pressure given to the said control valve below the said switching pressure, when the temperature measured with the said measuring apparatus is below a predetermined temperature. Hydraulic system for working machine as described in. A measuring device for measuring the temperature of the hydraulic oil;
The said 2nd setting part keeps the opening degree of the said control valve less than the said switching opening degree, when the temperature measured with the said measuring apparatus is below a predetermined temperature. Working machine hydraulic system.   The first setting unit sets the pilot pressure applied to the control valve to a pressure corresponding to the operation of the operation member when the operation member is operated. The hydraulic system of the working machine described in Crab.   The said 2nd setting part sets the opening degree of the said control valve to the opening degree according to operation of the said operation member, when the operation member is operated. The hydraulic system of the working machine described in Crab.

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