JP2018100773A - Hydraulic system of work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic system of a work machine, which can easily reduce the pressure in an oil passage connected to hydraulic equipment or the like.SOLUTION: A hydraulic system of a work machine comprises: a first operation device 47; a second operation device 48; a first selector valve 75 having an output port 75a that outputs the higher pressure between the pressure of hydraulic oil outputted from a first travel operation valve 55A and the pressure of hydraulic oil outputted from a third travel operation valve 59A; a second selector valve 76 having an output port 76a that outputs the higher pressure between the pressure of hydraulic oil outputted from a second travel control valve 55B and the pressure of hydraulic oil outputted from a fourth travel control valve 59B; a third selector valve 77 having an output port 77a that outputs the higher pressure between the pressure of the hydraulic oil outputted from the output port of the first selector valve and the pressure of the hydraulic oil outputted from the output port of the second selector valve; a detection device 78 that is connected to the output port of the third selector valve and detects a flow of the hydraulic oil; and a reduction part 70 that is connected to the output port of the third selector valve and can reduce the pressure of the hydraulic oil.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a hydraulic system for a work machine such as a skid steer loader or a compact truck loader.

  Conventionally, it is necessary to reduce the output of hydraulic equipment or the like in a work machine due to various circumstances. For example, in Patent Document 1, when a load greater than a predetermined value is applied to the engine, the output of a traveling pump, which is one of hydraulic devices, is reduced. Specifically, the working machine of Patent Document 1 includes an engine, a travel pump driven by the engine, a travel operation lever, and an operation valve that can change the pressure of the pilot oil (pilot pressure) according to the operation of the travel operation lever. And a pressure control valve provided on the upstream side of the operation valve.

Japanese Patent No. 5687970

  In the working machine of Patent Document 1, when a load exceeding a predetermined value is applied to the engine, the pressure of the hydraulic oil (primary pressure) entering the operation valve is operated by operating a pressure control valve arranged on the upstream side of the operation valve. This reduces the output of the traveling pump. As described above, when the pressure on the primary side of the operation valve is reduced as a method of reducing the output of the traveling pump, etc., all hydraulic devices connected to the operation valve, that is, devices other than the traveling pump, do not want to decrease the output. The output of the hydraulic equipment will also decrease.

  The present invention has been made to solve the above-described problems of the prior art, and provides a hydraulic system for a working machine that can easily reduce the pressure of an oil passage connected to a hydraulic device or the like. With the goal.

The technical means of the present invention for solving this technical problem is as follows.
The hydraulic system of the work machine operates in one direction and the other direction with a hydraulic pump that discharges hydraulic oil, a first oil passage through which the hydraulic oil discharged from the hydraulic pump flows, a traveling hydraulic device that can be operated by the hydraulic oil A first operating member capable of being connected to the first oil passage and connected to the first oil passage, and a first traveling operation valve capable of changing the pressure of the hydraulic oil according to an operation in one direction of the first operating member. And a first traveling device having a second traveling operation valve capable of changing the pressure of the hydraulic oil according to an operation in the other direction of the first operating member, and connected to the traveling hydraulic device, and the first operation A second operating member operable in one direction and the other direction, connected to the first oil passage and operated in one direction according to the operation in one direction of the second operating member. A third travel operation valve that is changeable, connected to the first oil passage and A fourth travel operation valve capable of changing the pressure of the hydraulic oil in accordance with an operation in the other direction of the operation member, and a second operation device connected to the travel hydraulic device and output from the first travel operation valve A first selection valve having an output port for outputting a high pressure out of the pressure of hydraulic oil and the pressure of hydraulic oil output from the third traveling operation valve; and the pressure of hydraulic oil output from the second traveling operation valve; A second selection valve having an output port for outputting a higher pressure of the hydraulic oil pressure output from the fourth travel operation valve; the hydraulic oil pressure output from the output port of the first selection valve; A third selection valve having an output port that outputs a higher pressure of the hydraulic oil pressure output from the output port of the selection valve; and a detection connected to the output port of the third selection valve and detecting the flow of the hydraulic oil Device and an output port of the third selection valve And it is connected to the bets and a, and a reduction unit which can reduce the pressure of the hydraulic oil.

  The hydraulic system of the work machine operates in one direction and the other direction with a hydraulic pump that discharges hydraulic oil, a first oil passage through which the hydraulic oil discharged from the hydraulic pump flows, a traveling hydraulic device that can be operated by the hydraulic oil A first operating member capable of being connected to the first oil passage and connected to the first oil passage, and a first traveling operation valve capable of changing the pressure of the hydraulic oil according to an operation in one direction of the first operating member. And a first traveling device having a second traveling operation valve capable of changing the pressure of the hydraulic oil according to an operation in the other direction of the first operating member, and connected to the traveling hydraulic device, and the first operation A second operating member operable in one direction and the other direction, connected to the first oil passage and operated in one direction according to the operation in one direction of the second operating member. A third travel operation valve that is changeable, connected to the first oil passage and A fourth travel operation valve capable of changing the pressure of the hydraulic oil in accordance with an operation in the other direction of the operation member, and a second operation device connected to the travel hydraulic device and output from the first travel operation valve A first selection valve having an output port for outputting a high pressure out of the pressure of hydraulic oil and the pressure of hydraulic oil output from the third traveling operation valve; and the pressure of hydraulic oil output from the second traveling operation valve; A second selection valve having an output port for outputting a high pressure of the hydraulic oil pressure output from the fourth travel operation valve; and an output port of the first selection valve and an output port of the second selection valve. And a detecting device for detecting the flow of hydraulic oil.

  According to the present invention, it is possible to easily reduce the pressure of an oil passage connected to a hydraulic device or the like.

It is the 1st schematic diagram of the hydraulic system in a 1st embodiment. It is a 2nd schematic diagram of the hydraulic system in a 1st embodiment. It is the schematic of the hydraulic system in 2nd Embodiment. It is the schematic of the hydraulic system in 3rd Embodiment. It is a figure which shows the 1st modification of the hydraulic system in 3rd Embodiment. It is a figure which shows the 2nd modification of the hydraulic system in 3rd Embodiment. It is the schematic of the hydraulic system in 4th Embodiment. It is the schematic of the hydraulic system in 5th 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. 7 shows a side view of the working machine according to the present invention. FIG. 7 shows a compact truck loader as an example of a work machine. However, the working machine according to the present invention is not limited to the compact truck loader 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. 7 and 8, 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. 7) of the driver seated on the driver's seat 8 of the work machine 1 is front, the rear side (right side in FIG. 7) is rearward, and the left side of the driver (FIG. 7). 7 on the left side and the right side of the driver (the back side in FIG. 7) 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 traveling hydraulic system will be described.
As shown in FIG. 1, the hydraulic system 30 includes a first hydraulic pump P1, a left traveling motor device (first traveling motor device) 31L, a right traveling motor device (second traveling motor device) 31R, and a prime mover 32. The first operating valve 33, the traveling hydraulic device 34, and the second operating valve 35 are provided.
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.

An oil passage (discharge 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 (first oil passage) 40 is provided with a first operation valve 33, a second operation valve 35, a first travel motor device 31L, and a second travel motor device 31R.
The first actuating valve 33 is an electromagnetic valve that changes the rotation of the first travel motor device 31L and the second travel motor device 31R, and can be switched between a first position 33a and a second position 33b by excitation. It is a valve. The switching operation of the first working valve 33 is performed by an operation member or the like not shown.

  The second operating valve 35 is an electromagnetic valve for switching whether or not to supply the operating oil to the discharge oil passage 40 on the downstream side of the second operating valve 35, and the first position 35 a and the second position 35 b are excited by excitation. It is a two-position switching valve that can be switched between. The switching operation of the second operating valve 35 is performed by a switch or the like provided around the driver's seat 8. When the switch is on, the second working valve 35 is switched to the first position 35a, and the working oil does not flow into the discharge oil passage 40 on the downstream side of the second working valve 35. When the switch is off, the second operating valve 35 is switched to the second position 35b, and the operating oil flows through the discharge oil passage 40 on the downstream side of the second operating valve 35.

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 traveling motor device 31 </ b> R is a motor that transmits power to the drive shaft of the traveling device 5 provided on the right side of the machine 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) 38. The travel motor 36 is a swash plate type variable capacity axial motor that can change the vehicle speed (rotation) to 1st speed or 2nd speed. The traveling motor 36 can change the traveling speed (rotational speed).

  The swash plate switching cylinder 37 is a cylinder that changes the angle of the swash plate of the traveling motor 36 by expansion and contraction. The travel control valve 38 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 38 is performed by the first operating valve 33 located on the upstream side connected to the travel control valve 38. Note that the configuration and operation of the second travel motor device 31R are the same as those of the first travel motor device 31L, and thus the description thereof is omitted.

The travel 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. And a drive circuit (right drive circuit) 34R for driving the motor device 31R.
The left drive circuit 34L and the right drive circuit 34R include travel pumps (travel hydraulic pumps) 53L and 53R, transmission oil passages (third oil passages) 57h and 57i, and a second charge oil passage 57j, respectively. Yes. The speed change oil passages (third oil passages) 57 h and 57 i are oil passages that connect the travel pumps 53 </ b> L and 53 </ b> R and the travel 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 traveling pumps 53L and 53R are swash plate type variable displacement axial pumps driven by the power of the prime mover 32. The traveling pumps 53L, 53R have a forward pressure receiving portion 53a and a reverse pressure receiving portion 53b on which pilot pressure acts. The angle of the swash plate is changed by the pilot pressure acting on the forward pressure receiving portion 53a and the reverse pressure receiving portion 53b. By changing the angle of the swash plate, it is possible to change the output (discharge amount of hydraulic oil) of the traveling pumps 53L and 53R and the discharge direction of the hydraulic oil.

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

Next, a working hydraulic system will be described.
As shown in FIG. 2, the hydraulic system 30 includes a plurality of control valves 56 and a work system hydraulic pump (second hydraulic pump) P2. 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.

  An oil passage (main oil passage) 39 is provided on the discharge side of the second hydraulic pump P2. A plurality of control valves 56 are connected to the main oil passage 39. The control valve 56 is a valve capable of switching the flow direction of the hydraulic oil by the pilot pressure of the pilot oil. 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.

  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.

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.
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 control oil path 86.
The control oil passage 86 is an oil passage through which pilot oil flows to the third control valve 56C via the proportional valve 60 (the first proportional valve 60A and the second proportional valve 60B). The control oil path 86 is composed of a steel pipe, a pipe, a hose and the like. The control 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 second proportional valve 60B and a pressure receiving portion 61b of the third control valve 56C. And a second control oil passage 86b to be connected.

  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.

  The control device 90 operates (opens and closes) the proportional valves 60 (the first proportional valve 60A and the second proportional valve 60B). The control device 90 is composed of a CPU and the like. 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.

When the operation member 93 is operated, the control device 90 applies a current corresponding to the operation amount of the operation member 93 to the solenoid of the first proportional valve 60A or the solenoid of the second proportional valve 60B. 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, the pilot pressure acting on the pressure receiving portion 61a of the third control valve 56C becomes more than a predetermined value. Then, the spool of the third control valve 56C is moved, and the third control valve 56C is switched from the third position 62c to the first position 62a. Further, for example, as a result of adjusting the opening of the second proportional valve 60B by swinging or sliding the operation member 93 in the other direction, the pilot pressure of the pressure receiving portion 61b of the third control valve 56C becomes more than a predetermined value. Then, the spool of the third control valve 56C is moved, and the third control valve 56C is switched from the third position 62c to the second position 62b. As described above, the auxiliary actuator can be operated by switching the control valve 56.

As shown in FIGS. 1 and 2, an operation (traveling operation) related to traveling of the work machine 1 and an operation (working operation) related to the work are performed by the first operating device 47 provided on the left side of the driver's seat 8 and the driver's seat 8. And the second operating device 48 provided on the right side.
Next, the first operating device 47 and the second operating device 48 will be described in detail.
The first operating device 47 is a device that can perform both a traveling operation and a work operation, and includes a first operating member 54. The first operation member 54 is a lever capable of performing a first operation that moves back and forth and a second operation that moves left and right (in the body width direction) different from the front and back. In other words, the first operating member 54 is a lever that can be moved in one direction (for example, front and left) and in another direction (for example, rear and right) different from the one direction.

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

  A plurality of pilot valves (operation valves) 55 are provided below the first operation member 54. The plurality of pilot valves 55 are a pilot valve 55A, a pilot valve 55B, a pilot valve 55C, and a pilot valve 55D. The pilot valve 55A, pilot valve 55B, pilot valve 55C, and pilot valve 55D are connected to the discharge oil passage 40 on the downstream side of the second operating valve 35.

The pilot valve 55A is a valve that operates in the first operation (front and rear operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the previous operation. The pilot valve 55B is a valve that is actuated in the post-operation of the first operation (front-rear operation), and the operation amount (operation) of the post-operation.
The hydraulic oil pressure that is output changes in response to this. That is, the pilot valve 55A and the pilot valve 55B are valves that are operated by the first operation, and move corresponding to the traveling operation.

  The pilot valve 55C is a valve that is operated by the left operation of the second operation (left and right operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the left operation. The pilot valve 55D is a valve that is operated by the right operation of the second operation (left and right operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the right operation. That is, the pilot valve 55C and the pilot valve 55D are valves that are operated by the second operation, and move corresponding to the work operation.

  The second operation device 48 is a device that can perform both a traveling operation and a work operation, and includes a second operation member 58. The second operating member 58 is a lever capable of performing a first operation that moves back and forth and a second operation that moves left and right (in the body width direction) different from the front and back. In other words, the second operating member 58 is a lever that can be moved in one direction (for example, front and left) and another direction (for example, rear and right) different from the one direction.

  In the second operation member 58, the first operation is assigned to the traveling operation, and the second operation is assigned to the work operation. That is, the second operation member 48 serves as both a travel operation member (travel operation member) and a work operation member (work operation member). The second operation member 58 is not limited to a lever as long as at least the first operation and the second operation can be performed independently.

  A plurality of pilot valves (operating valves) 59 are provided below the second operating member 58. The plurality of pilot valves 59 are a pilot valve 59A, a pilot valve 59B, a pilot valve 59C, and a pilot valve 59D. The pilot valve 59A, pilot valve 59B, pilot valve 59C and pilot valve 59D are connected to the discharge oil passage 40 on the downstream side of the second operating valve 35.

  The pilot valve 59A is a valve that operates in the previous operation of the second operation (front and back operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the previous operation. The pilot valve 59B is a valve that operates in the post-operation of the first operation (front-rear operation), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the post-operation. That is, the pilot valve 59A and the pilot valve 59B are valves that are operated by the first operation, and move corresponding to the traveling operation.

  The pilot valve 59C is a valve that is operated by the left operation of the first operation (left and right operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the left operation. The pilot valve 59D is a valve that is operated by the right operation of the second operation (left and right operations), and the pressure of the hydraulic oil that is output changes according to the operation amount (operation) of the right operation. That is, the pilot valve 59C and the pilot valve 59D are valves that are actuated by the second operation, and move corresponding to the work operation.

  From the above, among the plurality of pilot valves, the pilot valve 55A, the pilot valve 55B, the pilot valve 59A, and the pilot valve 59B operate in response to the traveling operation, and the pilot valve 55C, the pilot valve 55D, the pilot valve 59C, The pilot valve 59D operates in response to the work operation. For convenience of explanation, the pilot valve 55A, the pilot valve 55B, the pilot valve 59A, and the pilot valve 59B may be referred to as a first operation valve (travel operation valve). The pilot valve 55C, pilot valve 55D, pilot valve 59C, and pilot valve 59D may be referred to as a second operation valve (work operation valve).

Next, the relationship between the first operation valve (travel operation valve), the second operation valve (work operation valve), and the hydraulic equipment will be described. Reference numerals “W1”, “W2”, “D1”, and “D2” shown in FIGS. 1 and 2 indicate connection destinations of the oil passages.
The first operation valve (travel operation valve) and travel pumps 53L and 53R, which are one of travel hydraulic devices (travel hydraulic devices), are connected by a travel oil passage (second oil passage) 45. In other words, the traveling pumps 53L and 53R are first hydraulic devices that can be operated by the hydraulic oil output from the first operation valve.

  The traveling oil path 45 includes a first traveling oil path 45a, a second traveling oil path 45b, a third traveling oil path 45c, and a fourth traveling oil path 45d. The first traveling oil passage 45a is an oil passage that connects the first operating valve 55A and the forward pressure receiving portion 53a of the traveling pump 53L. The second traveling oil passage 45b is an oil passage that connects the first operating valve 55B and the reverse pressure receiving portion 53b for the traveling pump 53L. The third traveling oil passage 45c is an oil passage that connects the first operation valve 59A and the forward pressure receiving portion 53a of the traveling pump 53R. The fourth traveling oil passage 45d is an oil passage that connects the first operating valve 59B and the reverse pressure receiving portion 53b for the backward movement of the traveling pump 53R.

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

  When the first operation member 54 is tilted rearward, the first operation valve 55B is operated and the pilot pressure is output from the first operation valve 55B. This pilot pressure acts on the reverse pressure receiving portion 53b for the reverse travel. When the second operation member 58 is tilted rearward, the first operation valve 59B is operated, and pilot pressure is output from the first operation valve 59B. The pilot pressure acts on the reverse pressure receiving portion 53b for the traveling pump 53R.

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

Further, when one of the first operating member 54 and the second operating member 58 is swung forward and the other is swung rearward, the left traveling motor 36 and the right traveling motor 36 are in different directions. As a result, the work machine 1 turns right or left.
As described above, by moving the first operation member 54 back and forth or by moving the second operation member 58 back and forth, it is possible to perform a traveling operation for moving the work implement 1 forward, backward, right turn, and left turn.

Further, the second operation valve (work operation valve) and the control valve 56 which is one of the working system hydraulic devices (work hydraulic devices) are connected by a work oil passage (fourth oil passage) 46. In other words, the control valve 56 is a second hydraulic device that can be operated by the hydraulic oil output from the second operation valve.
The working oil passage 46 includes a first working oil passage 46a, a second working oil passage 46b, a third working oil passage 46c, and a fourth working oil passage 46d. The first working oil passage 46a is an oil passage that connects the second operation valve 55C and the pressure receiving portion 56a of the first control valve 56A. The second working oil passage 46b is an oil passage that connects the second operation valve 55D and the pressure receiving portion 56b of the first control valve 56A. The third working oil passage 46c is an oil passage connecting the second operation valve 59C and the pressure receiving portion 56a of the second control valve 56B. The fourth working oil passage 46d is an oil passage that connects the second operation valve 59D and the pressure receiving portion 56b of the second control valve 56B.

When the first operation member 54 is tilted to the left, the second operation valve 55C is operated and the pilot pressure of the pilot oil output from the second operation valve 55C is set. This pilot pressure acts on the pressure receiving portion 56a of the first control valve 56A, the boom cylinder 14 extends, and the boom 10 rises.
When the first operation member 54 is tilted to the right, the second operation valve 55D is operated, and the pilot pressure of the pilot oil output from the second operation valve 55D is set. This pilot pressure acts on the pressure receiving portion 56b of the first control valve 56A, the boom cylinder 14 contracts, and the boom 10 descends.

When the second operation member 58 is tilted to the left, the second operation valve 59C is operated, and the pilot pressure of the pilot oil output from the second operation valve 59C is set. The pilot pressure acts on the pressure receiving portion 56a of the second control valve 56B, the bucket cylinder 15 contracts, and the bucket 11 performs a squeeze operation.
When the second operation member 58 is tilted to the right, the second operation valve 59D is operated and the pilot pressure of the pilot oil output from the second operation valve 59D is set. This pilot pressure acts on the pressure receiving portion 56b of the second control valve 56B, the bucket cylinder 15 extends, and the bucket 11 performs a dumping operation.

Therefore, by moving the first operation member 58 left and right or by moving the second operation member 58 left and right, it is possible to perform work operations such as raising and lowering the boom 10, bucket dumping operation or squeezing operation.
The hydraulic system 30 is provided with a circuit that can reduce (depressurize) the hydraulic oil pressure in the traveling oil passage (second oil passage) 45. As shown in FIG. 1, a traveling oil passage (second oil passage) 45 connecting the traveling pumps 53L and 53R and the first operation valve is branched, and the hydraulic oil in the traveling oil passage 45 is branched to the branched oil passage. The reduction part (decompression part) 70 which can reduce the pressure of this is provided.

Specifically, the traveling oil passage (second oil passage) 45 includes a first branch oil passage 451a, a second branch oil passage 451b, a third branch oil passage 451c, a fourth branch oil passage 451d, and a fifth branch. And an oil passage 451e.
The first branch oil passage 451a is an oil passage that branches from a midway portion of the first travel oil passage 45a. The second branch oil passage 451b is an oil passage that branches from a midway portion of the second travel oil passage 45b. The third branch oil passage 451c is an oil passage that branches off from a middle portion of the third travel oil passage 45c. The fourth traveling oil passage 45d is an oil passage that branches off from a middle portion of the fourth traveling oil passage 45d. The fifth branch oil passage 451e is an oil passage connecting the first branch oil passage 451a, the second branch oil passage 451b, the third branch oil passage 451c, and the fourth branch oil passage 451d. The reduction unit 70 is connected to the fifth branch oil passage 451e.

In each of the first branch oil passage 451a, the second branch oil passage 451b, the third branch oil passage 451c, and the fourth traveling oil passage 451d, the hydraulic oil flows from the branch portion toward the fifth branch oil passage 451e. A check valve 71 is provided to allow and prevent the hydraulic oil from flowing from the fifth branch oil passage 451e toward the branch portion.
The travel oil passage (second oil passage) 45 includes a first operation valve to a branch oil passage (first branch oil passage 451a, second branch oil passage 451b, third branch oil passage 451c, and fourth branch oil passage 451d). The throttle part 49 which reduces the flow volume of the hydraulic oil which reaches is provided.

  The diaphragm unit 49 includes a first diaphragm unit 49a, a second diaphragm unit 49b, a third diaphragm unit 49c, and a fourth diaphragm unit 49d. The first throttle portion 49a is a throttle provided in a section (main oil passage) between the branch portion branched into the first branch oil passage 451a and the first operation valve 55A in the first traveling oil passage 45a. The second throttle portion 49b is a throttle provided in a section (main oil passage) between the branch portion branched to the second branch oil passage 451b and the first operation valve 55B in the second traveling oil passage 45b. The third throttle portion 49c is a throttle provided in the section (main oil passage) between the branch portion that branches into the third branch oil passage 451c and the first operation valve 59A in the third traveling oil passage 45c. The fourth throttle portion 49d is a throttle provided in the section (main oil passage) between the branch portion branched to the fourth branch oil passage 451d and the first operation valve 59B in the fourth traveling oil passage 45d.

The reduction unit 70 is an electromagnetic proportional valve (proportional valve) whose opening degree can be changed by exciting a solenoid. The proportional valve 70 has a primary port (pump port) 70a, a secondary port 70b, and a discharge port 70c. The primary port 70a of the proportional valve 70 is closed by a plug member 72 such as a plug. The secondary port 70b of the proportional valve 70 is connected to the traveling oil passage 45 and the fifth branch oil passage 451e. The discharge port 70c is connected to the hydraulic oil tank 22 via an oil passage (sixth oil passage) 73 for discharging the hydraulic oil. In the embodiment, the sixth oil passage 73 is connected to the hydraulic oil tank 22, but any oil passage that discharges the hydraulic oil may be used.
In addition to 2, it may be connected to the suction circuit of the pump, or may be connected to other circuits.

  According to the proportional valve 70, if the opening degree is changed from the fully closed state, the secondary port 70b and the discharge port 70c are connected, and the hydraulic oil in the fifth branch oil passage 451e is allowed to pass through the secondary port 70b. It can be discharged from the discharge port 70c. That is, with the above-described configuration, the fifth travel oil passage 451e, that is, the first travel oil passage 45a, the second travel oil passage 45b, and the third travel oil connected to the fifth branch oil passage 451e by the proportional valve 70. The pressure of the hydraulic oil in the path 45c and the fourth traveling oil path 45d can be reduced.

  The control device 90 changes the opening degree of the proportional valve 70. A detection device 91 that detects the load of the prime mover 32 is connected to the control device 90. For example, the engine speed is input to the detection device 91 as an index indicating the load of the prime mover 3. The control device 90 outputs a control signal for opening the proportional valve 70 when the engine speed is equal to or lower than a predetermined value. As a result, when the proportional valve 70 is opened, the pressure of the traveling oil passage 45 is released, and the outputs of the traveling pumps 53L and 53R can be reduced. Accordingly, the proportional valve 70 can reduce the pressure on the secondary side of the first operation valve (travel operation valve) and reduce the output of the travel pumps 53L and 53R, so that engine stall can be prevented. Note that the pressure on the secondary side of the first operation valve (traveling operation valve) may be reduced when the load on the prime mover is directly measured and the load on the prime mover exceeds a predetermined value.

In the embodiment described above, in order to prevent engine stall, the pressure in the traveling oil passage 45 (secondary pressure of the first operation valve) is reduced by opening the proportional valve 70. The pressure in the passage 45 may be lowered.
A switch (parking switch) 92 that can be switched on or off is connected to the control device 90. When the switch 92 is turned on, the work device 4 operates in a state where traveling is stopped. Specifically, when the switch 92 is turned on, the control device 90 outputs a control signal for fully opening the proportional valve 70. As a result, when the proportional valve 70 is fully opened, the pressure of the traveling oil passage 45 is released, the hydraulic oil discharged from the traveling pumps 53L and 53R is almost lost, and the rotation of the traveling motor 36 is stopped. Therefore, the proportional pressure valve 70 is used to reduce the pressure on the secondary side of the first operation valve (travel operation valve) to zero, so that the work machine 1 is stopped by stopping the travel motor 36 and the work device 4 is stopped. Can move.

As described above, the variable relief valve or the balance-type relief valve is used as the configuration for reducing the pressure on the secondary side of the first operation valve, that is, as the reduction unit (pressure reduction unit) 70 for reducing the pressure in the second oil passage 45. May be. If the primary port 70a is closed by the plug member 72 such as a plug while the secondary port 70b of the proportional valve 70 is connected to the device to be controlled (hydraulic device) as in this embodiment, the proportional valve By opening 70, the pressure in the second oil passage 45 is reduced. In other words, even if the variable relief valve is not installed in the secondary side oil passage of the first operating valve, if there is a proportional valve (electromagnetic proportional valve) 70, the pressure on the secondary side is reduced to output the hydraulic equipment. Can be reduced. In this embodiment, the output of the traveling hydraulic equipment connected to one of the traveling oil passages (second oil passage) 45 and the working oil passage (fourth oil passage) 46 can be reduced. In addition, you may make it reduce the output of the working hydraulic equipment connected to the other working oil path among the traveling oil path (2nd oil path) 45 and the working oil path (4th oil path) 46. FIG.
[Second Embodiment]
FIG. 3 shows a part of the hydraulic system in the second embodiment. FIG. 3 shows a part of the hydraulic system, but the other parts are the same as those in the above-described embodiment. Further, the description of the same configuration as that of the above-described embodiment is omitted.

In the hydraulic system of the second embodiment, not only the pressure on the secondary side of the first operation valve (traveling operation valve) but also the circuit that can reduce the pressure on the secondary side of the second operation valve (work operation valve). It is.
As shown in FIG. 3, the first travel oil passage 45a and the second travel oil passage 45b are connected to a travel hydraulic device (travel pump 53L). The first branch oil passage 451a branched from the middle portion of the first travel oil passage 45a and the second branch oil passage 451b branched from the middle portion of the second travel oil passage 45b are connected by a sixth branch oil passage 451f. ing.

  The first working oil passage 46a and the second working oil passage 46b are connected to a working hydraulic device (control valve 56A). The first branch oil passage 461a branched from the middle portion of the first working oil passage 46a and the second branch oil passage 461b branched from the middle portion of the second work oil passage 46b are connected by a sixth branch oil passage 451f. Yes. That is, the sixth branch oil passage 451 f is an oil passage that is both a part of the traveling oil passage 45 and a part of the work oil passage 46.

  In addition, the working oil passage (fourth oil passage) 46 has a throttle portion 42 that reduces the flow rate of the working oil from the second operation valve to the branch oil passage (first working oil passage 46a, second working oil passage 46b). Is provided. The diaphragm unit 42 includes a first diaphragm unit 42a and a second diaphragm unit 42b. The first throttle portion 42a is a throttle provided in a section (main oil passage) between the branch portion that branches into the first branch oil passage 461a and the second operation valve 55C in the first working oil passage 46a. The second throttle portion 42b is a throttle provided in a section (main oil passage) between the branch portion branched to the second branch oil passage 461b and the second operation valve 55D in the second working oil passage 46b.

A check valve 74 is provided in the first branch oil passage 461a and the second branch oil passage 461b. The check valve 74 is a valve that allows the hydraulic oil to flow from the branch portion toward the sixth branch oil passage 451f and prevents the hydraulic oil from flowing from the sixth branch oil passage 451f toward the branch portion. .
The set pressure of the check valve 74 provided in the fourth oil passage 46 (the first branch oil passage 461a and the second branch oil passage 461b) is different from the set pressure of the check valve 71 provided in the second oil passage 45. It is preferable to make it. For example, when the set pressure can be changed in the check valve 71 (when it can be set by a spring or the like), the check valve 71 is set to a predetermined set pressure, and the check valve 74 is more than the check valve 71. Use a low set pressure.

  The reducing unit 70 is connected to the sixth branch oil passage 451f. That is, the reduction unit 70 is connected to the second oil passage 45 and the fourth oil passage 46. The secondary port 70b of the proportional valve 70 is connected to the sixth branch oil passage 451f. The primary port 70 a is closed by a plug member 72 such as a plug, and the discharge port 70 c is connected to the hydraulic oil tank 22 via an oil passage (sixth oil passage) 73.

  According to the proportional valve 70, if the opening degree is changed from the fully closed state, the secondary port 70b and the discharge port 70c are connected, and the hydraulic oil in the sixth branch oil passage 451f passes through the secondary port 70b. It can be discharged from the discharge port 70c. In other words, with the above configuration, the proportional valve 70 can reduce both the hydraulic oil in the predetermined traveling oil passage 45 and the hydraulic oil pressure in the predetermined working oil passage 46.

In the work system hydraulic system, the work hydraulic equipment such as the control valve 56A can be operated in accordance with the operation of the work operation member such as the second operation member 48. For example, the control valve 56A can be forcibly returned to the neutral position by operating the proportional valve 70 to lower the secondary pressure of the predetermined working oil passage 46. Further, for example, when the working hydraulic device is the control valve 56B, the operation of the bucket cylinder 15 (the squeezing operation of the bucket 11 is performed) by operating the proportional valve 70 and lowering the secondary pressure in the third working oil passage 46c. That is, it is possible to slow down the operation of a specific hydraulic device among a plurality of operating hydraulic devices included in the hydraulic system.
[Third Embodiment]
FIG. 4A shows a part of the hydraulic system in the third embodiment. 4A to 4C show a part of the hydraulic system, the other parts are the same as those of the above-described embodiment. Further, the description of the same configuration as that of the above-described embodiment is omitted. For convenience of explanation, in the third embodiment, in the plurality of travel operation valves (pilot valve 55A, pilot valve 55B, pilot valve 59A, pilot valve 59B), the pilot valve 55A is replaced by the first travel operation valve and the pilot valve 55B. This is called the second travel operation valve, the pilot valve 59A is called the third travel operation valve, and the pilot valve 59B is called the fourth travel operation valve.

As shown in FIG. 4, the first travel operation valve 55A is connected to the first travel oil passage 45a. The second travel operation valve 55B is connected to the second travel oil passage 45b. The third travel operation valve 59A is connected to the third travel oil passage 45c. The fourth travel operation valve 59B is connected to the fourth travel oil path 45d.
The first branch oil passage 451a of the first travel oil passage 45a and the third branch oil passage 451c of the third travel oil passage 45c are connected to the first selection valve 75. The second branch oil passage 451b of the second travel oil passage 45b and the fourth branch oil passage 451d of the fourth travel oil passage 45d are connected to the second selection valve 76. The first selection valve 75 and the second selection valve 76 are connected by a fifth branch oil passage 451e provided with a third selection valve 77. A detection device (pressure sensor, pressure switch) 78 for detecting the pressure of hydraulic oil is connected to the fifth branch oil passage 451e. When a predetermined pressure is input to the detection device 78, the switch is turned on or the flow of hydraulic oil by the pressure sensor is detected.

The first selection valve (shuttle valve) 75 includes the pressure of hydraulic oil in the first branch oil passage 451a (hydraulic oil output from the first travel operation valve 55A) and hydraulic oil in the third branch oil passage 451c (third travel). Among the pressures of the hydraulic fluid output from the operation valve 59A), an output port 75a that outputs hydraulic fluid having a high pressure is provided.
The second selection valve (shuttle valve) 76 includes the pressure of the hydraulic oil in the second branch oil passage 451b (the hydraulic oil output from the second travel operation valve 55B) and the working oil in the fourth branch oil passage 451d (fourth travel). Among the pressures of the hydraulic fluid output from the operation valve 59B), an output port 76a for outputting hydraulic fluid having a high pressure is provided.

  The third selection valve (shuttle valve) 77 is the pressure of the hydraulic oil pressure output from the output port 75a of the first selection valve 75 and the hydraulic oil pressure output from the output port 76a of the second selection valve 76. An output port 77a for outputting high hydraulic oil is provided. The output port 77 a of the third selection valve (shuttle valve) 77 is connected to a reduction unit 70 that is an electromagnetic proportional valve (proportional valve). That is, the secondary port 70 b of the proportional valve 70 is connected to the output port 77 a of the third selection valve (shuttle valve) 77.

  According to the hydraulic system of FIG. 4A, when the first operation member 54 and the second operation member 58 are swung rearward, the hydraulic oil is output from the second selection valve 76 and the fifth branch oil passage 451e. Therefore, the backward movement of the work machine 1 can be detected. In the hydraulic system of the present invention, the reverse operation is performed using the first operation member 54 disposed on the left side of the driver's seat 8 and the second operation member 58 disposed on the right side of the driver's seat 8. Therefore, the first travel operation valve 55A and the second travel operation valve 55B operated by the first operation member 54, and the third travel operation valve 59A and the fourth travel operation valve 59B operated by the second operation member 58 are provided. It is arranged with the driver's seat 8 in between. Here, if the first traveling operation valve 55A, the second traveling operation valve 55B, the third traveling operation valve 59A, and the fourth traveling operation valve 59B are provided with detection devices, not only a large number of detection devices are necessary, Many harnesses for connecting the detection device and the control device 90 are also required. By using the hydraulic system shown in FIG. 4A, only one detection device and harness are required, and the work of arranging the harness on the left and right can be reduced.

And if the opening degree of the proportional valve 70 is changed, the secondary port 70b and the discharge port 70c will be connected, and it can discharge | emit from the discharge port 70c of the 5th branch oil path 451e. That is, with the above configuration, the proportional valve 70 reduces the pressure of the hydraulic oil in the first traveling oil path 45a, the second traveling oil path 45b, the third traveling oil path 45c, and the fourth traveling oil path 45d. Can do.
FIG. 4B shows a first modification of the third embodiment, and FIG. 4C shows a second modification of the third embodiment.

  As shown in FIG. 4B, a first branch oil passage 451a and a third branch oil passage 451c are connected to the first selection valve 75. A second branch oil passage 451b and a fourth branch oil passage 451d are connected to the second selection valve 76. The first selection valve 75 and the second selection valve 76 are connected by a seventh branch oil passage 451g. A detection device 78 that detects the pressure of the hydraulic oil is connected to the seventh branch oil passage 451g. According to the hydraulic system of FIG. 4B, when the first operating member 54 and the second operating member 58 perform a traveling operation, hydraulic fluid is output from the first selection valve 75 or the second selection valve 76 and the second operation valve 58 is operated. Since it flows through the seven branch oil passage 451g, it is possible to detect that the traveling operation has been performed by the detection device 78.

As shown in FIG. 4C, a second branch oil passage 451b and a fourth branch oil passage 451d are connected to the second selection valve 76. A detection device 78 is connected to the output port of the second selection valve 76. According to the hydraulic system of FIG. 4C, when the first operating member 54 and the second operating member 58 are operated to move the work implement 1 backward, the hydraulic oil is output from the second selection valve 76 and is detected by the detection device 78. Can be detected.
[Fourth Embodiment]
FIG. 5 shows a hydraulic system according to a fourth embodiment. The hydraulic system of the fourth embodiment is a modification of the connection destination of the proportional valve 70. The description of the same configuration as that of the above-described embodiment is omitted.

  As shown in FIG. 5, a plurality of hydraulic devices 100 are provided in the hydraulic system of the work machine. The plurality of hydraulic devices 100 are connected by a plurality of fifth oil passages 101. The fifth oil passage 101 is an oil passage through which hydraulic oil flows, for example, an oil passage through which the hydraulic oil discharged from the first hydraulic pump P1 and the second hydraulic pump P2 flows. The fifth oil passage 101 includes the traveling oil passage (second oil passage) 45 or the working oil passage (fourth oil passage) 46 described above.

  The hydraulic device 100 is various devices that construct a hydraulic system, and is a device that is operated by hydraulic oil. For example, the hydraulic device 100 is a hydraulic motor that rotates with hydraulic oil, a hydraulic cylinder that expands and contracts with hydraulic oil, a control valve that changes the flow rate or direction of hydraulic oil, a switching valve, an operation valve, and the like. The proportional valve 70 is provided at various locations in order to depressurize the fifth oil passage 101. For example, as shown in FIG. 5, a fifth oil passage 101 that connects the first hydraulic pump P <b> 1 and the operation valve 55, a fifth oil passage 101 that connects the second hydraulic pump P <b> 2 and the hydraulic device 100, and the hydraulic device 100. Can be connected to a fifth oil passage 101 that connects the hydraulic device 100 and the hydraulic device 100. The primary port 70a of the proportional valve 70 is closed by a plug member 72 such as a plug. The secondary port 70 b is connected to the fifth oil passage 101. The discharge port 70 c is connected to the hydraulic oil tank 22 via an oil passage (sixth oil passage) 73. Therefore, according to the proportional valve 70, various hydraulic oils in the fifth oil passage 101 can be caused to flow to the hydraulic oil tank 22 by opening the proportional valve 70. That is, the proportional valve 70 can be used as a pressure reducing valve that reduces the pressure in the fifth oil passage 101. FIG. 5 shows an example in which the proportional valve 70 is adopted as a pressure reducing valve. In a hydraulic system (hydraulic circuit), the proportional valve 70 can be provided at various locations shown in FIG.

Moreover, the hydraulic pumps P1 and P2 described above are examples, and any pumps that can discharge hydraulic oil may be used.
FIG. 6 shows a hydraulic system according to a modification of the reduction unit. The reduction unit in FIG. 6 is applicable to all the embodiments described above. As shown in FIG. 6, the reducing unit 70 includes an electromagnetic proportional valve (proportional valve) 79a and a check valve 79b. The proportional valve 79a has a primary port 70a, a secondary port 70b, and a discharge port 70c.

  A discharge oil passage 40 provided on the discharge side of the first hydraulic pump P1 is connected to the primary port 70a of the proportional valve 79a. The secondary port 70b of the proportional valve 79a is connected to an oil passage (fifth oil passage) to which a plurality of hydraulic devices are connected. As shown in FIG. 6, for example, the secondary port 70b of the proportional valve 79a is connected to the second oil passage 45 connected to the traveling hydraulic equipment and the fourth oil passage 46 connected to the working hydraulic equipment. That is, the secondary port 70 b is connected to the sixth branch oil passage 451 f that also serves as the second oil passage 45 and the fourth oil passage 46. The discharge port 70c is connected to the hydraulic oil tank 22 via an oil passage (sixth oil passage) 73 for discharging the hydraulic oil.

  The check valve 79b is connected to an oil passage that connects the proportional valve 79a and the hydraulic device. For example, the check valve 79 b is provided in the second oil passage 45 and the fourth oil passage 46. For example, the check valve 79b includes a first check valve 791b provided in the first branch oil passage 461a and a second check valve 792b provided in the second branch oil passage 461b. In other words, the first check valve 791b and the second check valve 792b are the same as the check valve 74 described above. The first check valve 791b and the second check valve 792b allow hydraulic oil to flow toward the secondary port 70b of the proportional valve 79a, and a predetermined hydraulic device (working hydraulic device) from the proportional valve 79a. Prevents hydraulic fluid from flowing into the tank.

  As described above, according to the modified example of FIG. 6, the primary port 70a of the proportional valve 79a is connected to the oil passage (discharge oil passage 40) of the first hydraulic pump P1, and the secondary port 70b of the proportional valve 79a is connected to the traveling hydraulic equipment. Even when connected to an oil passage connected to a plurality of hydraulic devices such as a working hydraulic device, the sixth branch oil is caused by the proportional valve 79a and the check valve 79b (the first check valve 791b and the first check valve 791b). It is possible to reduce the pressure of the hydraulic oil in the passage 451f.

  For example, when the pressure of the hydraulic oil flowing in the fourth oil passage 46 in the working hydraulic equipment is higher than the pressure of the hydraulic oil flowing in the second oil passage 45 in the traveling hydraulic equipment, the opening degree of the proportional valve 79a is increased. As shown by the arrow C, the hydraulic oil in the sixth branch oil passage 451f can pass through the check valve 79b, enter the proportional valve 79a, and be discharged from the discharge port 70c. In other words, the pressure of the hydraulic oil can be lowered by the proportional valve 79a and the check valve 79b in the same manner as the relief valve.

  In the above-described embodiment, the check valve 74 provided in the fourth oil passage 46 is described as the check valve 79b included in the reduction unit 70, but the check valve 71 provided in the second oil passage 45 is also It functions as a check valve 79b included in the reduction unit 70. For example, when the pressure of the hydraulic oil flowing in the second oil passage 45 in the traveling hydraulic equipment is higher than the pressure of the hydraulic oil flowing in the fourth oil passage 46 in the working hydraulic equipment, increasing the opening of the proportional valve 79a, As shown by the arrow D, the hydraulic oil in the sixth branch oil passage 451f can pass through the check valve 71 and enter the proportional valve 79a and be discharged from the discharge port 70c.

The hydraulic equipment and the oil passage shown in FIG. 6 are examples, and are not limited to the hydraulic equipment and the oil passage shown in FIG. 6, and the proportional valve 79a and the check valve 79b are applicable to all the hydraulic equipment and the oil passage. Is possible. Further, the pressure of the hydraulic oil can be reduced even with the switching valve by providing a check valve 79b as a reduction unit by connecting to the secondary port of the switching valve such as a two-position switching valve.
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.

32 Motor 34 Traveling hydraulic device 36 Traveling motor 38 Traveling control valve (hydraulic switching valve)
40 Discharge oil passage (first oil passage)
45 Traveling oil passage (second oil passage)
46 Working oil passage (fourth oil passage)
47 First operating device 48 Second operating device 50 Connecting members 53L, 53R Traveling pump (traveling hydraulic pump)
56 Control valves 57h, 57i Transmission oil passage (third oil passage)
70 Reduction part (decompression part)
70a Primary port 70b Secondary port 70c Discharge port 71 Check valve 73 Oil passage (sixth oil passage)
74 Check valve 75 First selection valve 76 Second selection valve 76a Output port 77 Third selection valve 77a Output port 78 Detection device 79a Proportional valve 79b Check valve 86 Control oil passage 91 Detection device 93 Operation member 100 Hydraulic device 101 First 5 oil passage P1 first hydraulic pump P2 second hydraulic pump

Claims (2)

A hydraulic pump that discharges hydraulic oil;
A first oil passage for flowing hydraulic oil discharged from the hydraulic pump;
Traveling hydraulic equipment that can be operated by hydraulic oil;
A first operation member operable in one direction and the other direction, a first traveling operation valve connected to the first oil passage and capable of changing a pressure of hydraulic oil according to an operation in one direction of the first operation member; A first operation connected to the travel hydraulic device, having a second travel operation valve connected to the first oil passage and capable of changing the pressure of hydraulic oil in response to an operation in the other direction of the first operation member. Equipment,
An operation device different from the first operation device, a second operation member operable in one direction and the other direction, connected to the first oil passage, and according to an operation in one direction of the second operation member A third travel operation valve capable of changing the pressure of the hydraulic oil; a fourth travel operation valve connected to the first oil passage and capable of changing the pressure of the hydraulic oil in response to an operation in the other direction of the second operation member. A second operating device connected to the traveling hydraulic device;
A first selection valve having an output port for outputting a high pressure among the pressure of the hydraulic oil output from the first travel operation valve and the pressure of the hydraulic oil output from the third travel operation valve;
A second selection valve having an output port for outputting a high pressure out of the pressure of the hydraulic oil output from the second travel operation valve and the pressure of the hydraulic oil output from the fourth travel operation valve;
A third selection valve having an output port for outputting a higher pressure among the pressure of hydraulic oil output from the output port of the first selection valve and the pressure of hydraulic oil output from the output port of the second selection valve;
A detection device connected to the output port of the third selection valve and detecting the flow of hydraulic oil;
A reduction unit connected to the output port of the third selection valve and capable of reducing the pressure of the hydraulic oil;
The working machine's hydraulic system. A hydraulic pump that discharges hydraulic oil;
A first oil passage for flowing hydraulic oil discharged from the hydraulic pump;
Traveling hydraulic equipment that can be operated by hydraulic oil;
A first operation member operable in one direction and the other direction, a first traveling operation valve connected to the first oil passage and capable of changing a pressure of hydraulic oil according to an operation in one direction of the first operation member; A first operation connected to the travel hydraulic device, having a second travel operation valve connected to the first oil passage and capable of changing the pressure of hydraulic oil in response to an operation in the other direction of the first operation member. Equipment,
An operation device different from the first operation device, a second operation member operable in one direction and the other direction, connected to the first oil passage, and according to an operation in one direction of the second operation member A third travel operation valve capable of changing the pressure of the hydraulic oil; a fourth travel operation valve connected to the first oil passage and capable of changing the pressure of the hydraulic oil in response to an operation in the other direction of the second operation member. A second operating device connected to the traveling hydraulic device;
A first selection valve having an output port for outputting a high pressure among the pressure of the hydraulic oil output from the first travel operation valve and the pressure of the hydraulic oil output from the third travel operation valve;
A second selection valve having an output port for outputting a high pressure out of the pressure of the hydraulic oil output from the second travel operation valve and the pressure of the hydraulic oil output from the fourth travel operation valve;
A detection device connected to the output port of the first selection valve and the output port of the second selection valve and detecting the flow of hydraulic oil;
The working machine's hydraulic system.

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