JP2018194074A - Hydraulic system of working machine and control valve - Google Patents

Abstract

To easily operate a plurality of control valves (hydraulic actuators) in a series circuit.SOLUTION: A hydraulic system of a working machine comprises: a hydraulic pump for discharging a working fluid; a first hydraulic apparatus operated by the working fluid; a second hydraulic apparatus operated by the working fluid, and different from the first hydraulic apparatus; a first control valve for controlling the first hydraulic apparatus; a second control valve arranged at a downstream side of the first control valve, and controlling the second hydraulic apparatus; a communication passage for connecting the first hydraulic apparatus and the first control valve to each other, and making return oil being the working fluid which returns to the first control valve from the first hydraulic apparatus flow; a supply oil passage for connecting the first control valve and the second control valve to each other, and supplying the return oil to the second control valve; a connection oil passage formed at the first control valve, and connecting the communication passage and the supply oil passage; a discharge oil passage connected to the first control valve; a setting part arranged at the discharge oil passage, and boosting the pressure of the discharge oil passage; a branch flow passage branched from the connection oil passage, and connected to the discharge oil passage; and a throttle part arranged at the branch flow passage.SELECTED DRAWING: Figure 1

Description

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

  Conventionally, Patent Document 1 is known as a hydraulic system for a working machine. The working machine disclosed in Patent Document 1 includes a boom, a bucket, a boom cylinder that operates the boom, a bucket cylinder that operates the bucket, a spare actuator that operates the spare attachment, and a first control valve that controls expansion and contraction of the boom cylinder. And a second control valve for controlling expansion and contraction of the bucket cylinder, and a third control valve for operating the auxiliary actuator.

JP 2010-270527 A

  In the working machine of Patent Document 1, when the spool of the first control valve is not operated, the hydraulic oil discharged from the pump passes through the inside of the first control valve, and the second control valve and the third control valve. Can be supplied. On the other hand, when the spool of the first control valve is operated, the hydraulic oil (return oil) returned from the boom cylinder to the first control valve can be supplied to the second control valve and the third control valve. . That is, in the hydraulic circuit of the working machine of Patent Document 1, the return oil returned from the upstream control valve (first control valve) is supplied to the downstream control valves (second control valve, third control valve). A series circuit is used. However, in the series circuit, it may be difficult to operate the downstream second control valve, the third control valve, or the like when the upstream control valve is operated.

  The present invention has been made to solve the above-described problems of the prior art, and provides a hydraulic system for a work machine that can easily operate a plurality of control valves (hydraulic actuators) in a series circuit. The purpose is to provide.

  A hydraulic system for a work machine includes a hydraulic pump that discharges hydraulic oil, a first hydraulic device that is operated by hydraulic oil, a second hydraulic device that is operated by hydraulic oil and is different from the first hydraulic device, and a first hydraulic device. A first control valve that controls, a second control valve that is provided downstream of the first control valve and controls the second hydraulic device, and connects the first hydraulic device and the first control valve and from the first hydraulic device A communication path through which return oil, which is hydraulic oil that returns to the first control valve, flows, a supply oil path that connects the first control valve and the second control valve, and supplies the return oil to the second control valve, and the first control valve And a connecting oil passage that connects the communication passage and the supply oil passage, a discharge oil passage that is connected to the first control valve, and a setting portion that is provided in the discharge oil passage and increases the pressure of the discharge oil passage A branch flow path branched from the connection oil path and connected to the discharge oil path, and provided in the branch flow path And Ri part, is equipped with a.

The first hydraulic device is a hydraulic cylinder that expands and contracts, and the communication path includes a first communication path through which return oil when contracted and a second communication path through which return oil when expanded, and a connection oil path The return oil communicated from the second communication passage and discharged from the second communication passage flows, and the supply oil passage communicated from the connection oil passage and discharged from the connection oil passage to the second control valve. Supply.
Further, the hydraulic oil discharged from the hydraulic pump has a discharge oil passage that supplies the first control valve and the second control valve, and the discharge oil passage includes a first discharge oil passage connected to the first control valve, A second discharge oil passage that communicates from the discharge oil passage and merges with the first discharge oil passage, and a third discharge oil passage that communicates from the discharge oil passage are provided.

The setting unit includes an operation valve that is provided in the third discharge oil passage and increases the pressure of the third discharge oil passage.
The working valve is a first check valve that allows working oil from the second discharge oil passage to the third discharge oil passage and blocks hydraulic oil from the third discharge oil passage to the second discharge oil passage. .
The setting unit includes an oil cooler that cools the hydraulic oil discharged from the first discharge oil passage.

The setting unit is provided in the discharge oil passage and includes any of an oil cooler, a check valve, a throttle, and a relief valve.
The setting unit is a throttle provided in the drain oil passage.
A hydraulic system for a work machine includes a hydraulic pump that discharges hydraulic oil, a first hydraulic device that is operated by hydraulic oil, a second hydraulic device that is operated by hydraulic oil and is different from the first hydraulic device, and a first hydraulic device. A first control valve to be controlled, a second control valve provided on the downstream side of the first control valve and controlling the second hydraulic device, and the first hydraulic device and the first control valve are connected to each other from the first hydraulic device A first communication passage for flowing return oil, which is hydraulic oil that returns to the first control valve, and a return oil that is hydraulic oil that connects the first hydraulic device and the first control valve and returns from the first hydraulic device to the first control valve. And a second communication path that is different from the first communication path, a supply oil path that connects the first control valve and the second control valve, and supplies return oil to the second control valve, and a first control valve. And a first connection oil passage that connects the first communication passage and the supply oil passage, and a first control valve that is provided to the second communication passage. A second connection oil passage that is connected to the oil passage and is different from the first connection oil passage, a discharge oil passage that is connected to the first control valve, and is branched from the first connection oil passage and connected to the discharge oil passage. A first branch passage, a second branch passage branched from the second connection oil passage and connected to the discharge oil passage, a first throttle portion provided in the first branch passage, and a second branch flow And a second diaphragm portion that is provided in the path and is smaller than the first diaphragm portion.

  The first hydraulic device is a hydraulic cylinder that expands and contracts, discharges the return oil when contracted to the first communication path, and discharges the return oil when extended to the second communication path. The return oil communicated from the first communication path and discharged from the first communication path flows, and the supply oil path communicates from the first connection oil path and discharges the return oil discharged from the first connection oil path to the second control valve. And the return oil discharged from the second communication passage flows through the second connection oil passage, and the supply oil passage communicates from the second connection oil passage and the second connection oil. Return oil discharged from the passage is supplied to the second control valve.

Moreover, it has the 2nd non-return valve which is provided in the discharge oil path, accept | permits the hydraulic oil discharged | emitted from a 1st control valve, and blocks | prevents the hydraulic oil which goes to a 1st control valve.
Also, a first port to which a first oil passage connected to the first hydraulic device is connected, a second port to which a second oil passage connected to the first hydraulic device is connected, and a hydraulic pressure for discharging hydraulic oil The third port to which the third oil passage connected to the pump is connected, the fourth port to which the first discharge oil passage for discharging the hydraulic oil is connected, and the hydraulic oil that has passed through the first port or the second port A fifth port that discharges to the outside, a first port, a second port, a third port, a fourth port, a first internal oil passage connected to the fifth port, a second internal oil passage, a third internal oil passage, A main body having a fourth internal oil path and a fifth internal oil path, and a first internal oil path, a second internal oil path, a third internal oil path, a fourth internal oil path, and a The communication destination of the five internal oil passages can be changed, and the second internal oil passage and the fifth internal oil passage communicate with each other, or the first internal oil passage and the fifth internal oil passage A spool that is movable between a communicating position and a neutral position is provided, and when the spool is between the communicating position and the neutral position, the second internal oil path and the fourth internal oil path or the first internal oil path And a fourth internal oil passage.

Further, when the first internal oil passage and the third internal oil passage communicate with each other, the spool communicates with the second internal oil passage and the fifth internal oil passage.
The first communication portion includes a first extending oil passage extending in the longitudinal direction of the spool, a plurality of second extending oil passages extending from one end of the first extending oil passage to the outer peripheral surface of the spool, And a plurality of third extending oil passages extending from the midway portion of the extending oil passage to the outer peripheral surface of the spool.

  Further, the spool has a second communication portion capable of communicating the first internal oil passage and the third internal oil passage, and the second communication portion is a recess formed in the outer peripheral surface of the spool.

  According to the present invention, a plurality of control valves (hydraulic actuators) can be easily operated in a series circuit.

It is a figure which shows the hydraulic system (hydraulic circuit) in 1st Embodiment. It is a figure which shows the modification of the hydraulic system (hydraulic circuit) in 1st Embodiment. It is a figure which shows the hydraulic system (hydraulic circuit) in 2nd Embodiment. It is an internal view of the control valve in a neutral position. It is an internal view of the control valve between a neutral position and a 1st position. It is an internal view of the control valve in the 1st position. 1 is an overall view of a skid steer loader exemplified as a working machine.

[First Embodiment]
FIG. 5 shows a side view of the working machine 1 according to the present invention. In FIG. 5, a skid steer loader is shown as an example of the work machine 1. However, the working machine according to the present invention is not limited to the skid steerer, and may be another type of loader working machine such as a compact truck loader. Moreover, a working machine other than the loader working machine may be used.

The work machine 1 includes a machine body (vehicle body) 2, a cabin 3, a work device 4, and travel devices 5A and 5B.
A cabin 3 is mounted on the body 2. A driver's seat 8 is provided at the rear of the cabin 3. In the embodiment of the present invention, the front side (left side in FIG. 5) of the driver seated on the driver's seat 8 of the work machine 1 is front, the rear side (right side in FIG. 5) is rearward, and the left side of the driver (FIG. 5). The front side (5) is the left side, and the right side of the driver (the back side in FIG. 5) is 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 work device 4 is a device that performs work, and is mounted on the machine body 2. The traveling device 5 </ b> A is a device that travels the body 2, and is provided on the left side of the body 2. The traveling device 5 </ b> B is a device that travels the body 2, and is provided on the right side of the body 2. A prime mover 7 is provided at the rear of the machine body 2. The prime mover 7 is a diesel engine (engine). The prime mover 7 is not limited to an engine, and may be an electric motor or the like.

On the left side of the driver's seat 8, a travel lever 9L is provided. A travel lever 9 </ b> R is provided on the right side of the driver seat 8. The left traveling lever 9L operates the left traveling device 5A, and the right traveling lever 9R operates the right traveling device 5B.
The work device 4 includes a boom 10, a bucket 11, a lift link 12, a control link 13, a boom cylinder (hydraulic cylinder) 14, and a bucket cylinder 17. The boom 10 is provided on the side of the body 2. The bucket 11 is provided at the tip (front end) of the boom 10. The lift link 12 and the control link 13 support the base (rear part) of the boom 10. The boom cylinder 14 drives the boom 10 up or down.

  Specifically, the lift link 12, the control link 13, and the boom cylinder 14 are provided on the side of the machine body 2. The upper part of the lift link 12 is pivotally supported by the upper part of the base part of the boom 10. The lower part of the lift link 12 is pivotally supported on the side part of the rear part of the airframe 2. The control link 13 is disposed in front of the lift link 12. One end of the control link 13 is pivotally supported at the lower part of the base portion of the boom 10, and the other end is pivotally supported by the body 2.

  The boom cylinder 14 is a hydraulic cylinder that raises and lowers the boom 10. The upper part of the boom cylinder 14 is pivotally supported by the front part of the base part of the boom 10. The lower part of the boom cylinder 14 is pivotally supported by the side part of the rear part of the body 2. When the boom cylinder 14 is expanded and contracted, the boom 10 is swung up and down by the lift link 12 and the control link 13. The bucket cylinder 17 is a hydraulic cylinder that swings the bucket 11. The bucket cylinder 17 connects the left part of the bucket 11 and the left boom, and connects the right part of the bucket 11 and the right boom. A spare attachment such as a hydraulic crusher, a hydraulic breaker, an angle bloom, an auger, a pallet fork, a sweeper, a mower, and a snow blower can be attached to the tip (front) of the boom 10 instead of the bucket 11. .

In the present embodiment, wheel type traveling devices 5A and 5B having front wheels 5F and rear wheels 5R are employed as the traveling devices 5A and 5B. Note that crawler type (including semi-crawler type) traveling devices 5A and 5B may be employed as the traveling devices 5A and 5B.
Next, a work system hydraulic circuit (work system hydraulic system) provided in the skid steer loader 1 will be described.

As shown in FIG. 1, the working system hydraulic system is a system for operating the boom 10, bucket 11, spare attachment, and the like, and includes a control valve unit 70 and a working system hydraulic pump (first hydraulic pump) P1. ing. Further, a second hydraulic pump P2 different from the first hydraulic pump P1 is provided.
The first hydraulic pump P1 is a pump that is operated by the power of the prime mover 7, and is constituted by a constant capacity gear pump. The first hydraulic pump P <b> 1 can discharge the hydraulic oil stored in the tank (hydraulic oil tank) 15. The second hydraulic pump P2 is a pump that is operated by the power of the prime mover 7, and is constituted by a constant capacity gear pump. The second hydraulic pump P <b> 2 can discharge the hydraulic oil stored in the tank (hydraulic oil tank) 15. The second hydraulic pump P2 discharges hydraulic fluid for signal and hydraulic fluid for control in the hydraulic system. The hydraulic fluid for signal and the hydraulic fluid for control are called pilot oil.

  The control valve unit 70 includes a plurality of control valves 20. The plurality of control valves 20 are valves that control various hydraulic actuators (hydraulic devices) provided in the work machine 1. The hydraulic actuator is a device that operates with hydraulic oil, such as a hydraulic cylinder or a hydraulic motor. In this embodiment, the plurality of control valves 20 are a first control valve 20A, a second control valve 20B, and a third control valve 20C.

First, the second control valve 20B and the third control valve 20C will be described.
The second control valve 20 </ b> B is a valve that controls a hydraulic cylinder (bucket cylinder) 17 that controls the bucket 11. In other words, the second control valve 20B is a valve that controls the bucket cylinder 17 that is a second hydraulic device that is operated by hydraulic oil. The third control valve 20C is a valve that controls a hydraulic actuator (hydraulic cylinder, hydraulic motor, etc.) 16 attached to the preliminary attachment.

  Each of the second control valves 20B is a pilot type direct acting spool type three-position switching valve. The second control valve 20B switches to a neutral position 20b3, a first position 20b1 different from the neutral position 20b3, a neutral position 20b3, and a second position 20b2 different from the first position 20b1. In the second control valve 20B, the neutral position 20b3, the first position 20b1, and the second position 20b2 are switched by moving the spool by operating the operation member. A bucket cylinder 17 is connected to the second control valve 20B through an oil passage.

  Therefore, when the second control valve 20B is brought to the first position 20b1 by operating the operation member, the bucket cylinder 17 contracts. Due to the contraction of the bucket cylinder 17, the bucket 11 performs a squeeze operation. If the second control valve 20B is brought to the second position 20b2 by operating the operation member, the bucket cylinder 17 extends. The bucket cylinder 17 is dumped by the expansion of the bucket cylinder 17. Note that the switching of the second control valve 20B is performed by directly moving the spool by the operation member, but the spool may be moved by the pressure of the hydraulic oil (pilot oil). The second control valve 20B is connected to the first control valve 20A by a central oil passage 68a. The second control valve 20B and the third control valve 20C are connected by a central oil passage 68b. When the second control valve 20B is in the neutral position 20b3, the hydraulic oil supplied to the second control valve 20B is supplied to the third control valve 20C via the central oil passage 68b.

  Each of the third control valves 20C is a pilot type direct acting spool type three-position switching valve. The third control valve 20C switches to a neutral position 20c3, a first position 20c1 different from the neutral position 20c3, a neutral position 20c3, and a second position 20c2 different from the first position 20c1. In the third control valve 20C, the neutral position 20c3, the first position 20c1, and the second position 20c2 are switched by moving the spool by the pilot oil pressure. The connection member 18 is connected to the third control valve 20C via supply / discharge oil passages 83a and 83b. The supply / discharge oil passages 83a and 83b include a first supply / discharge oil passage 83a and a second supply / discharge oil passage 83b. An oil path connected to the hydraulic actuator 16 of the preliminary attachment is connected to the connecting member 18.

  Therefore, if the third control valve 20C is set to the first position 20c1, the working oil can be supplied from the first supply / discharge oil passage 83a to the hydraulic actuator 16 of the preliminary attachment. If the 3rd control valve 20C is set to the 2nd position 20c2, hydraulic fluid can be supplied to the hydraulic actuator 16 of a preliminary | backup attachment from the 2nd supply / discharge oil path 83b. In this way, by supplying hydraulic oil to the hydraulic actuator 16 from the supply / discharge oil passage 83a or the supply / discharge oil passage 83b, the hydraulic actuator 16 (preliminary attachment) can be operated. When the third control valve 20C is at the neutral position 20c3, the hydraulic oil supplied from the central oil passage 68b to the third control valve 20C is discharged from the central oil passage 68c connected to the third control valve 20C. .

Next, the first control valve will be described.
As shown in FIG. 1, the first control valve 20A is a valve applicable to a series circuit. In a series circuit having an upstream control valve (for example, the first control valve 20A) and a downstream control valve (for example, the second control valve 20B), the first hydraulic control actuator 20A operates the first control valve 20A when the first control valve 20A is activated. The hydraulic oil (return oil) that has returned to the control valve 20A flows to the second control valve 20B. The first control valve 20A is a valve capable of outputting a part of the return oil returned from the hydraulic actuator during operation to an oil passage for discharging the hydraulic oil. In the present embodiment, the first control valve 20A is connected to a hydraulic cylinder (boom cylinder) 14 that is one of hydraulic actuators via an oil passage. In other words, the first control valve 20A is a valve that controls a boom cylinder) 14 that is a first hydraulic device that is operated by hydraulic oil. Further, the first control valve 20A discharges the hydraulic oil returned from the boom cylinder 14 to a fourth oil passage (discharge oil passage) 24 described later.

  The boom cylinder 14 includes a cylindrical body 14a, a rod 14b provided movably on the cylindrical body 14a, and a piston 14c provided on the rod 14b. The boom cylinder 14 and the first control valve 20A are connected via communication paths 21 and 22. The communication passages 21, 22 have a first oil passage (first communication passage) 21 and a second oil passage (second communication passage) 22. In other words, the first oil passage (first communication passage) 21 is an oil passage through which return oil flows when the boom cylinder 14 that is the first hydraulic device contracts. The second oil passage (second communication passage) 22 is an oil passage through which return oil flows when the boom cylinder 14 which is the first hydraulic device is extended. The first oil passage 21 and the second oil passage 22 can flow hydraulic oil and are pipe materials such as hydraulic hoses, pipes, and joints.

  A first supply / discharge port 14d for supplying and discharging hydraulic oil is provided at the base end of the cylindrical body 14a (the side opposite to the rod 14b side). A second supply / discharge port 14e for supplying and discharging hydraulic oil is provided at the distal end portion (on the rod 14b side) of the cylindrical body 14a. When the boom cylinder 14 contracts, the boom cylinder 14 discharges hydraulic oil from the first supply / discharge port 14d. When the boom cylinder 14 extends, the boom cylinder 14 discharges hydraulic oil from the second supply / discharge port 14e. One end of a first oil passage 21 is connected to the first supply / discharge port 14d, and one end of a second oil passage 22 is connected to the second supply / discharge port 14e. That is, the second oil passage 22 is an oil passage connected to the boom cylinder 14 at a position different from the first oil passage 21 connected to the boom cylinder 14.

As shown in FIG. 1, each of the first control valves 20A is a pilot type direct acting spool type three-position switching valve. The first control valve 20A switches to a neutral position 20a3, a first position 20a1 different from the neutral position 20a3, a neutral position 20a3, and a second position 20a2 different from the first position 20a1.
The first control valve 20A has a plurality of ports. As shown in FIG. 1, the plurality of ports include a first port 31, a second port 32, a third port 33, a fourth port 34, and a fifth port 35.

  The first port 31 is a port that connects the other end of the first oil passage 21 connected to the boom cylinder 14. Accordingly, the hydraulic oil traveling from the first port 31 toward the boom cylinder 14 passes through the first oil passage 21 and enters the first supply / discharge port 14 d of the boom cylinder 14. Further, the hydraulic oil traveling from the first supply / discharge port 14 d toward the first control valve 20 </ b> A enters the first port 31 through the first oil passage 21.

  The second port 32 is a port for connecting the other end of the second oil passage 22 connected to the boom cylinder 14. Accordingly, the hydraulic oil traveling from the second port 32 toward the boom cylinder 14 passes through the second oil passage 22 and enters the second supply / discharge port 14e of the boom cylinder 14. Further, the hydraulic oil traveling from the second supply / discharge port 14 e toward the first control valve 20 </ b> A enters the second port 32 through the second oil passage 22.

  The third port 33 is a port to which a third oil passage (main oil passage) 23 connected to the first hydraulic pump P1 that discharges hydraulic oil is connected. Specifically, the third oil passage 23 is branched into three in the middle, and the first branch oil passage 23a, the second branch oil passage 23b, and the third branch oil passage 23c are connected to the third port 33. It is connected to the. That is, the third port 33 includes a port 33a connected to the first branch oil passage 23a, a port 33b connected to the second branch oil passage 23b, and a port 33c connected to the third branch oil passage 23c. Contains.

The fourth port 34 is a port to which a fourth oil passage (discharge oil passage) 24 connected to the hydraulic oil tank 15 is connected. Specifically, the fourth oil passage 24 includes an oil passage 24a. The oil passage 24 a is an oil passage through which the hydraulic oil that has passed through the first control valve 20 </ b> A flows to the hydraulic oil tank 15.
The discharge oil passage 24a includes a first discharge portion 24a1 connected to the first oil passage 21, a second discharge portion 24a2 connected to the second oil passage 22, a first discharge portion 24a1 and a second discharge portion 24a2. 3rd discharge part 24a3 which connects these, and 4th discharge part 24a4 which connects 3rd discharge part 24a3 and hydraulic oil tank 15 are included. Here, the oil passage including the third discharge portion 24a3 and the fourth discharge portion 24a4 may be referred to as first discharge oil passages 24a3 and 24a4. Further, the discharge oil passage 24 includes a second discharge oil passage 24b. The second discharge oil passage 24b is an oil passage that branches from the discharge oil passage 68 and flows the hydraulic oil that has passed through the second control valve 20B and the hydraulic oil that has passed through the third control valve 20C to the oil passage 24a. The second exhaust oil passage 24b is an oil passage that joins the first exhaust oil passage 24a3.

  A relief valve 27 is connected to the first discharge part 24a1 and the second discharge part 24a2. The first discharge portion 24a1 and the second discharge portion 24a2 are provided with a bypass oil passage that connects both sides of the relief valve 27, and a check valve 29 is provided in the bypass oil passage. The check valve 29 allows the hydraulic oil to flow from the discharge oil passage 24 side toward the communication passage (the first communication passage 21 and the second communication passage 22), and from the communication passage to the discharge oil passage 24 side. It is a valve that prevents the flow. The 4th discharge part 24a4 is connected with the 2nd discharge oil path 24b. The third discharge portion 24a3 includes a connecting portion 26a that connects the first discharge portion 24a1 and the second discharge portion 24a2, and branch discharge portions 26b and 26c branched from the connecting portion 26a into at least two. Branch discharge portions 26b and 26c are connected to the fourth port 34 of the first control valve 20A. That is, the fourth port 34 includes a port 34a connected to the branch discharge unit 26b and a port 34b connected to the branch discharge unit 26c. In the present embodiment, the fourth port 34 is a port including two ports 34a and 34b, but the number of ports is not limited. For example, the number of ports may be one.

The fifth port 35 is a port for discharging hydraulic oil that has passed through the first port 31 or the second port 32 to the outside. That is, the fifth port 35 receives the hydraulic oil (return oil) returned from the boom cylinder 14 to the first port 31 or the hydraulic oil (return oil) returned from the boom cylinder 14 to the second port 32 downstream. This is a port that discharges to the side control valve (second control valve 20B).
The working hydraulic system includes a fifth oil passage 25. The fifth oil passage 25 is an oil passage through which return oil flows to the second control valve 20B when the first control valve 20A is activated (when the spool 50 of the first control valve 20A is moving). Specifically, when the first control valve 20A is in the first position 20a1, the first control valve 20A and the second control valve 20B are connected by a fifth oil passage (supply oil passage) 25. The fifth oil passage 25 supplies the return oil that returns from the first hydraulic actuator 14 to the first control valve 20A via the first oil passage 21 through the first control valve 20A and supplies the second control valve 20B.

  One end of the fifth oil passage 25 is branched into two, one first supply oil passage (one branch passage after branching) 25a and the other second supply oil passage (the other after branching). (Supply oil passage) 25 b is connected to the fifth port 35. In other words, the fifth port 35 includes a port 35a connected to one first supply oil passage 25a and a port 35b connected to the other second supply oil passage 25b. In the present embodiment, the fifth port 35 is a port including two ports 35a and 35b, but the number of ports is not limited. For example, the number of ports may be one.

  When the first control valve 20A is in the second position 20a2, the first oil passage 21 and the fifth oil passage 25 are connected by the first connection oil passage 61a. The first connection oil passage 61a is also referred to as a connection oil passage. The first connection oil passage 61 a is an oil passage provided in the first control valve 20 </ b> A and communicating with the first oil passage 21. Specifically, the first connection oil passage 61a connects the first port 31 of the first control valve 20A and the fifth port 35 of the first control valve 20A when the first control valve 20A is set to the second position 20a2. It is an oil passage.

  The working system hydraulic system includes a branch channel (first branch channel) 65a that branches from the first connection oil channel 61a and discharges the return oil. The first branch flow path 65a is an oil path that branches from the first connection oil path 61a and communicates with the port 34a when the first control valve 20A is at the second position 20a2. The first branch channel 65a is provided with a throttle part (first throttle part) 67a for reducing the flow rate of the hydraulic oil. The first throttle portion 67a is configured, for example, by making a part of the first branch flow path 65a thinner than the other parts. In other words, the first branch flow path 65a is configured by making the cross-sectional area of the portion where the hydraulic oil flows smaller than other portions. In addition, the structure of the 1st aperture | diaphragm | squeeze part 67a is not limited to the example mentioned above.

  On the other hand, when the first control valve 20A is in the first position 20a1, the second oil passage 22 and the fifth oil passage 25 are connected by a second internal oil passage (second connection oil passage) 61b. The second connection oil passage 61b is also referred to as a connection oil passage. The second connection oil passage 61 b is an oil passage provided in the first control valve 20 </ b> A and communicating with the second oil passage 22. The second connection oil passage 61b is an oil passage that connects the second port 32 of the first control valve 20A and the fifth port 35 of the first control valve 20A when the first control valve 20A is set to the first position 20a1. It is.

  The working hydraulic system includes a branch channel (second branch channel) 65b that branches from the second connection oil passage 61b and discharges the return oil. Specifically, the second branch flow path 65b is an oil path that branches from the second connection oil path 61b and communicates with the port 34b when the first control valve 20A is at the first position 20a1. The second branch channel 65b is provided with a throttle part (second throttle part) 67b for reducing the flow rate of the hydraulic oil. For example, the second throttle portion 67b is configured by making a part of the second branch flow path 65b thinner than the other parts. In other words, the second branch flow path 65b is configured by making the cross-sectional area of the portion where the hydraulic oil flows smaller than other portions. In addition, the structure of the 2nd aperture | diaphragm | squeeze part 67b is not limited to the example mentioned above.

  In addition, the working system hydraulic system has a setting unit that increases the pressure of the drain oil passage 24 connected to the first branch passage 65a or the second branch passage 65b. As shown in FIG. 1, the setting unit includes a check valve (first check valve) 19 c that is an operation valve and an oil cooler 28. The check valve 19c is provided in the middle of the third discharge oil passage 24c communicating with the discharge oil passage 68 (the central oil passage 68a, the central oil passage 68b, and the central oil passage 68c). The check valve 19 c is a valve that allows the hydraulic oil to flow toward the hydraulic oil tank 22 and prevents the hydraulic oil from flowing toward the discharge oil passage 68. The check valve 19c has a setting member 19c1 for setting a differential pressure. The setting member 19c1 is configured by a spring or the like, and generates a differential pressure by pushing the valve body with a predetermined urging force from the side opposite to the direction in which the flow of hydraulic oil is allowed (direction to block). The oil cooler 28 is provided in the middle of the first discharge oil passages 24a3 and 24a4 connected to the second discharge oil passage 24b. The hydraulic oil discharged from the first discharged oil passages 24 a 3 and 24 a 4 flows into the inflow port 28 a of the oil cooler 28. A discharge port 28 b different from the inflow port 28 a of the oil cooler 28 is connected to the hydraulic oil tank 15. Here, when paying attention to the third discharge oil passage 24c and the second discharge oil passage 24b provided with the check valve 19c, the third discharge oil passage 24c and the second discharge oil passage 24b connect the connecting portion 26. Connected through. The check valve 19c allows hydraulic oil from the second discharged oil passage 24b to the third discharged oil passage 24c and blocks hydraulic oil from the third discharged oil passage 24c to the second discharged oil passage 24b.

  Therefore, in the section between the check valve 19c and the connection portion 26 and the section between the connection portion 26 and the inflow port 28a of the oil cooler 28, the pressure of the hydraulic oil is increased by the check valve 19c as a setting portion. Therefore, for example, when the hydraulic oil supplied to the fifth oil passage (supply oil passage) 25 is reduced, the hydraulic oil in the second exhaust oil passage 24b and the first exhaust oil passages 24a3 and 24a4 is separated from the branch passage. It can be supplied to the fifth oil passage 25 via 65a, 65b and the connecting oil passages 61a, 61b. For example, when the boom cylinder 14 is extended (the boom 10 is raised), the return oil is supplied to the fifth oil passage 25 via the second communication passage 22, the second port 32, and the second connection oil passage 61b. Will be. Here, when the bucket cylinder 17 is extended with the boom 10 raised (the dump of the boom 11), a relatively large amount of hydraulic oil is required, but the second discharge oil passage 24b and the first discharge oil passage are used. The hydraulic fluids 24a3 and 24a4 can be supplied to the fifth oil passage 25 via the branch passage 65b and the connection oil passage 61b. That is, the operation when dumping the bucket 11 while raising the boom 10 can be made smooth.

FIG. 2 shows a modification of the setting unit. As shown in FIG. 2, the setting unit is a throttle 67d provided in the fourth discharge part 24a4 and a throttle 67e provided in the third discharge oil passage 24c.
In the hydraulic system for the working machine described above, communication is made with the branch flow paths (first branch flow path 65a, second branch flow path 65b) branched from the connection oil paths (first connection oil path 61a, second connection oil path 61b). Setting sections (throttle 67d and throttling 67e) for increasing the pressure of the discharge oil passage (the branch discharge portions 26b and 26c of the first discharge oil passage 24a3) are provided.

  Accordingly, in the branch discharge portions 26b and 26c, the pressure in the section between the ports 34a and 34b and the setting portions (throttle 67d and throttling 67e) can be increased. For example, the fifth oil passage (supply oil passage) 25 When the amount of hydraulic oil to be supplied decreases, the hydraulic oil in the branch discharge portions 26b and 26c can be supplied to the fifth oil path via the branch flow paths 65a and 65b and the connection oil paths 61a and 61b.

  In the above-described embodiment, the branch flow paths 65a and 65b are provided corresponding to the first position 20a1 and the second position 20a2 of the first control valve 20A, respectively, but the branch flow corresponding to only the first position 20a1. A passage 65b may be provided, and the hydraulic oil of the discharge oil passage 24 may be supplied to the branch passage 65b. Moreover, the setting part should just raise the pressure of the discharge oil path 24, and the setting part may be the relief valve provided in the 4th discharge part 24a4 and the 3rd discharge oil path 24c.

  In the present embodiment, the exhaust oil passage 24 has two oil passages, that is, a second exhaust oil passage 24b and a third exhaust oil passage 24c, but the second exhaust oil passage 24b and the third oil passage 24b. When the discharge oil passage 24c is a single oil passage, the setting unit may be an oil cooler 28 and a check valve 19c provided in the middle of the oil passage. The setting unit may be the oil cooler 28, the check valve 19c, the throttle, the relief valve, or a combination thereof.

  The second throttle portion 67b has a smaller cross-sectional area of the portion through which hydraulic oil flows than the first throttle portion 67a. In other words, the second throttle portion 67b through which the return oil flows when the boom cylinder 14 is extended is a portion of the portion through which the return oil flows than the first throttle portion 67a through which the return oil flows when the boom cylinder 14 contracts. Small cross-sectional area. That is, the second diaphragm 67b is effective, and the first diaphragm 67a is less effective than the second diaphragm 67b. Accordingly, the flow rate of hydraulic oil supplied to the fifth oil passage 25 when the first control valve 20A is set to the first position 20a1 and the flow rate of hydraulic oil supplied to the fifth oil passage 25 when the first control valve 20A is set to the second position 20a2. Can be made substantially the same. Consider a cross section (a cross section in a direction perpendicular to the rod 14) of the rod 14b and the piston 14c in the boom cylinder 14. In the cross section, the cross sectional area of the piston 14c is larger than the cross sectional area of the rod 14b. Therefore, when the boom cylinder 14 is contracted, the amount of hydraulic oil discharged from the first supply / discharge port 14d is larger than when the boom cylinder 14 is extended. That is, when the boom cylinder 14 is contracted, the amount of hydraulic oil (the amount of return oil) that returns to the first oil passage 21 and the first port 31 increases. Conventionally, since the return oil is supplied to the second control valve 20B as it is, when the second control valve 20B is operated simultaneously with the first control valve 20A, the hydraulic actuator (bucket cylinder 17) operated by the second control valve 20B is operated. Usability is reduced. That is, the operational feeling differs depending on whether the first control valve 20A and the second control valve 20B are operated simultaneously or not. On the other hand, according to the first control valve 20A, since the cross-sectional area of the second throttle part 67b is smaller than the cross-sectional area of the first throttle part 67a, the hydraulic actuator (bucket cylinder 17) regardless of the expansion and contraction of the boom cylinder 14. It is possible to prevent the operation feeling of the camera from changing.

  In particular, when the boom cylinder 14 is extended (the boom 10 is raised), depending on the area ratio of the cross section (cross section in the direction orthogonal to the rod 14) of the rod 14b and the piston 14c of the cylinder 14, Less hydraulic oil (return oil) is discharged from the second supply / discharge port 14e than the supplied hydraulic oil. Further, when the bucket cylinder 17 is extended (the bucket 11 is dumped), an external force is applied in the direction in which the bucket cylinder 17 is extended, for example, by loading the bucket 11. As a result, the pressure in the fifth oil passage 25 becomes lower than that of the connection portion 26 and the inflow port 28a, so that the oil in the third discharge portion 24a3 flows into the second branch flow path 65b without returning to the tank 15.

Note that the same configuration as the first throttle portion 67a and the second throttle portion 67b in the present embodiment is also applicable to the second control valve 20B. In this case, the cross-sectional area of the portion through which the return oil flows is smaller in the throttle portion where the return oil flows when the bucket cylinder 17 extends than in the throttle portion where the return oil flows when the bucket cylinder 17 contracts.
[Second Embodiment]
FIG. 3 shows a second embodiment of the control valve 20 according to the present invention. The control valve 20 of the second embodiment can be applied to the control valve 20 of the first embodiment described above. The description of the same configuration as that of the first embodiment is omitted. As shown in FIG. 3, the hydraulic system of the work machine is a system in which the first branch flow path 65 a, the second branch flow path 65 b, and the setting unit (operating valve) are not provided.

As shown in FIG. 4A, the first control valve 20A includes a main body B1. The main body B1 is formed of a casting or a resin. An oil passage through which hydraulic oil flows is formed inside the main body B1. That is, the main body B1 includes a first internal oil passage 41, a second internal oil passage 42, a third internal oil passage 43, a fourth internal oil passage 44, and a fifth internal oil passage 45.
For convenience of explanation, in FIGS. 4A to 4C, the left side of the drawing is called left, the right side of the drawing is called right, the left and right directions are called the horizontal direction, and the direction orthogonal to the horizontal direction is called the vertical direction. Moreover, the 1st internal oil path 41, the 2nd internal oil path 42, the 3rd internal oil path 43, the 4th internal oil path 44, and the 5th internal oil path 45 are demonstrated by sectional view of FIG. 4A.

The first internal oil passage 41 is an oil passage formed inside the main body B <b> 1 and communicates with the first port 31. A first port 31 is provided on the left side of the main body B1 in the lateral direction, and a first internal oil passage 41 is formed following the first port 31. The first internal oil passage 41 extends at least in the vertical direction.
The second internal oil passage 42 is an oil passage formed inside the main body B <b> 1 and communicates with the second port 32. A second port 32 is provided on the right side of the main body B1 in the lateral direction, and a second internal oil passage 42 is formed following the second port 32. The second internal oil passage 42 extends at least in the vertical direction.

  The third internal oil passage 43 is an oil passage formed inside the main body B <b> 1 and communicates with the third port 33. A third internal oil passage 43 is formed at the center in the lateral direction of the main body B1. Specifically, the third internal oil passage 43 includes a left oil passage 43a, a right oil passage 43b, and a central oil passage 43c. The central oil passage 43c is formed at the center in the horizontal direction of the main body B1 and communicates with the port 33c. The left oil passage 43a is located to the left of the central oil passage 43c and communicates with the port 33a. The right oil passage 43b is located to the right of the central oil passage 43c and communicates with the port 33b. The left oil passage 43a and the central oil passage 43c communicate with each other, and the right oil passage 43b and the central oil passage 43c communicate with each other. The left oil passage 43a, the right oil passage 43b, and the central oil passage 43c extend at least in the vertical direction.

  The fourth internal oil passage 44 is an oil passage formed inside the main body B <b> 1 and communicates with the fourth port 34. Specifically, the fourth internal oil passage 44 includes a left oil passage 44a and a right oil passage 44b. The left oil passage 44a is formed on the left side of the main body B1 in the lateral direction and communicates with the port 34a. The left oil passage 44 a is located on the left side of the first internal oil passage 41. The right oil passage 44b is formed at the right side of the main body B1 in the lateral direction and communicates with the port 34b. The right oil passage 44 b is located on the right side of the second internal oil passage 42. The left oil passage 44a and the right oil passage 44b extend at least in the vertical direction.

  The fifth internal oil passage 45 is an oil passage formed inside the main body B <b> 1 and communicates with the fifth port 35. Specifically, the fifth internal oil passage 45 includes a left oil passage 45a and a right oil passage 45b. The left oil passage 45a is formed at the left side of the main body B1 in the lateral direction and communicates with the port 35a. The left oil passage 45 a is located between the first internal oil passage 41 and the left oil passage 44 a of the fourth internal oil passage 44. The right oil passage 45b is formed in the right portion of the main body B1 in the lateral direction and communicates with the port 35b. The right oil passage 45 b is located between the second internal oil passage 42 and the right oil passage 44 b of the fourth internal oil passage 44. The left oil passage 45a and the right oil passage 45b extend at least in the vertical direction.

  Now, an annular wall portion 36 (through hole 36a) extending from one end (left end) in the horizontal direction of the main body B1 to the other end (right end) is formed. That is, the body B1 is formed with a linear through hole 36a into which the spool 50 formed in a columnar shape is inserted. A first internal oil passage 41, a second internal oil passage 42, a third internal oil passage 43, a fourth internal oil passage 44, and a fifth internal oil passage 45 reach the annular wall portion 36 constituting the through hole 36a. ing. The end portion 41 a of the first internal oil passage 41 reaches the wall portion 36. An end portion 42 a of the second internal oil passage 42 reaches the wall portion 36. An end 43 a 1 of the left oil passage 43 a of the third internal oil passage 43 reaches the wall portion 36. The end portion 43 b 1 of the right oil passage 43 b of the third internal oil passage 43 reaches the wall portion 36. An end portion 43 c 1 of the central oil passage 43 c of the third internal oil passage 43 reaches the wall portion 36. An end portion 44 a 1 of the left oil passage 44 a of the fourth internal oil passage 44 reaches the wall portion 36. The end portion 44 b 1 of the right oil passage 44 b of the fourth internal oil passage 44 reaches the wall portion 36. An end portion 45 a 1 of the left oil passage 45 a of the fifth internal oil passage 45 reaches the wall portion 36. An end portion 45 b 1 of the right oil passage 45 b of the fifth internal oil passage 45 reaches the wall portion 36. The end 41a, the end 42a, the end 43a1, the end 43b1, the end 43c1, the end 44a1, the end 44b1, the end 45a1, and the end 45b1 are formed in a concave shape.

As shown in FIG. 4A, the first control valve 20 </ b> A has a spool 50. The spool 50 communicates with the first internal oil passage 41, the second internal oil passage 42, the third internal oil passage 43, the fourth internal oil passage 44, and the fifth internal oil passage 45 by moving inside the main body B1. The destination can be changed.
Hereinafter, the spool 50 will be described in detail.
The spool 50 is formed in a cylindrical shape. The cylindrical spool 50 is inserted into a through hole 36a formed in the main body B1. The left end or right end of the spool 50 protrudes from the main body B1. An operating member such as a lever is connected to a protruding portion (protruding portion) of the spool 50.

  The spool 50 has a first communication part 51. The first communication portion 51 is a portion that can communicate with the second internal oil passage 42, the fourth internal oil passage 44, and the fifth internal oil passage 45. Specifically, the first communication portion 51 includes a first extending oil passage 51a, a plurality of second extending oil passages 51b, a plurality of third extending oil passages 51c, and a first recess 51d. Yes. The first extending oil passage 51 a is an oil passage extending in the longitudinal direction (axial direction) inside the spool 50, and is configured by forming a hole extending in the axial direction inside the spool 50. The first extending oil passage 51a extends from the midway part of the spool 50 to the right part. The left end and the right end of the first extending oil passage 51a are closed. Accordingly, the hydraulic oil that has entered the first extending oil passage 51 a flows in the axial direction inside the spool 50.

The plurality of second extending oil passages 51b are oil passages extending from the left end of the first extending oil passage 51a to the outer peripheral surface of the spool 50, and communicate with the first extending oil passage 51a. A plurality of second extending oil passages 51b communicate with the left part of the first extending oil passage 51a. As shown in FIG. 4A, the spool 50 is provided with a plurality of second extending oil passages 51b at predetermined intervals in the circumferential direction.
The plurality of third extending oil passages 51c are oil passages extending from the midway portion of the first extending oil passage 51a to the outer peripheral surface of the spool 50, and communicate with the first extending oil passage 51a. A plurality of third extending oil passages 51c communicate with the middle portion of the first extending oil passage 51a. As shown in FIG. 4A, the spool 50 is provided with a plurality of third extending oil passages 51c at predetermined intervals in the circumferential direction.

The first concave portion 51d is a portion formed by denting the outer peripheral surface of the spool 50 in an annular shape. The first recessed portion 51d is a right portion of the spool 50 and is positioned so as to overlap the second extending oil passage 51b.
The spool 50 has a second communication portion 52.
The second communication portion 52 can communicate the first internal oil passage 41 and the fifth internal oil passage 45. Further, the second communication portion 52 can communicate the first internal oil passage 41 and the third internal oil passage 43. Specifically, the 2nd communication part 52 contains the 2nd recessed part 52a. The second recess 52a is a portion formed by recessing the outer peripheral surface of the spool 50 in an annular shape. The second recess 52 a is located on the left part of the spool 50.

  As shown in FIG. 4B, the spool 50 is positioned at a midway position (midway position 20a4) between the neutral position 20a3 and the first position 20a1. More specifically, the first recess 51d and the end 42a of the second internal oil passage 42 are overlapped (matched). Further, the third extending oil passage 51c and the right oil passage 44b (end portion 44b1) of the fourth internal oil passage 44 are overlapped (matched). That is, when the first control valve 20A is in the midway position 20a4, the second internal oil passage 42 and the fourth internal oil passage 44 can communicate with each other. When the first control valve 20A is in the midway position 20a4, the return oil that returns from the boom cylinder (first hydraulic device) 14 to the first control valve 20A, as indicated by R1 in FIG. The oil is discharged through the second internal oil passage 42, the first recess 51 d, the first communication portion 51, the fourth internal oil passage 44, and the fourth oil passage 24.

  As shown in FIG. 4C, the spool 50 is positioned at the first position 20a1 (communication position 20a1). More specifically, the first recess 51d, the end portion 42a of the second internal oil passage 42, and the right oil passage 45b (end portion 45b1) of the fifth internal oil passage 45 are overlapped (matched). Further, the third extending oil passage 51c and the right oil passage 44b (end portion 44b1) of the fourth internal oil passage 44 are overlapped (matched). The second recess 52 a, the end 41 a of the first internal oil passage 41, and the left oil passage 43 a (end 43 a 1) of the third internal oil passage 43 are overlapped (matched). That is, when the first control valve 20A is at the first position 20a1, the second internal oil passage 42, the fourth internal oil passage 44, and the fifth internal oil passage 45 can be communicated with each other.

  When the first control valve 20A is at the first position 20a1, the return oil that returns from the boom cylinder 14 to the first control valve 20A is returned to the second internal oil passage 42, the first communication portion, as indicated by R2 in FIG. 4C. 51, and is discharged through the fourth internal oil passage 44. The return oil that returns from the boom cylinder 14 to the first control valve 20 </ b> A passes through the second oil passage 22, the second internal oil passage 42, the first communication portion 51, the fifth internal oil passage 45, and the fifth oil passage 25. Via the second control valve 20B. When the first control valve 20A is at the first position 20a1, the hydraulic oil discharged from the hydraulic oil tank P1 is transferred to the third internal oil passage 43 (right oil passage 43a), the second oil passage R3 shown in FIG. 4C. 2 is supplied to the boom cylinder 14 through the internal oil passage 42, the second communication portion 52, the first internal oil passage 41 (end portion 41 a), and the first oil passage 21.

  As described above, the spool 50 has the first communication portion 51 that can communicate the second internal oil passage 42 and the fourth internal oil passage 44 when the spool 50 is in the midway position 20a4. Thus, when the spool 50 is moved from the neutral position 20a3 to the first position 20a1, the second internal oil path 42 and the fourth internal oil path 42 are communicated before the second internal oil path 42 and the fifth internal oil path 45 communicate with each other. Communication with the road 44 is possible. Further, when the spool 50 is moved from the neutral position 20a3 to the first position 20a1, the second internal oil path 42 and the fourth internal oil path are communicated before the first internal oil path 41 and the third internal oil path 43 communicate with each other. 44 can be communicated. For example, when focusing on the upstream control valve (first control valve 20A) and the downstream control valve (second control valve 20B), the second internal oil passage 42 and the fifth internal oil passage 45 communicate with each other. Since the second internal oil passage 42 and the fourth internal oil passage 44 can be communicated with each other before, the upstream control valve (second control valve 20B) is not dependent on the downstream control valve (second control valve 20B). Since the hydraulic oil that has passed through the first control valve 20A) can be discharged, the upstream first hydraulic device 14 can be stably operated.

  Further, the spool 50 has a first communication portion 51 that can communicate with the second internal oil passage 42, the fourth internal oil passage 44, and the fifth internal oil passage 45. The first communicating portion 51 includes a first extending oil passage 51a extending in the longitudinal direction of the spool 50, and a plurality of second extending oil passages 51b extending from one end of the first extending oil passage 51a to the outer peripheral surface of the spool 50. And a plurality of third extending oil passages 51c extending from the midway portion of the first extending oil passage 51a to the outer peripheral surface of the spool 50. Thus, the first communicating portion 51 is provided by forming the first extending oil passage 51a, the second extending oil passage 51b, and the third extending oil passage 51c in the inside and the outer peripheral surface of the spool 50. be able to. For this reason, even if it does not process main part B1, hydraulic fluid can be discharged by the 1st communicating part 51 provided in spool 50.

  Note that the same configuration as that of the first communication portion 51 can be applied to the left side of the spool 50. That is, if the same configuration as that of the first position 20a1 is also applied to the second position 20a2, when the spool 50 is moved from the neutral position 20a3 to the second position 20a2, the first internal oil passage 41 and the fifth internal oil passage 45 are moved. Can communicate with the first internal oil passage 41 and the fourth internal oil passage 44. When the spool 50 is moved from the neutral position 20a3 to the second position 20a2, before the second internal oil path 42 and the third internal oil path 43 communicate with each other, the first internal oil path 41 and the fourth internal oil Communication with the road 44 is possible.

As mentioned above, although this invention was demonstrated, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. 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.
In the embodiment described above, the first hydraulic device is the boom cylinder 14 and the second hydraulic device is the bucket cylinder 17, but other hydraulic cylinders may be used and are not limited. Further, the discharge oil passage 24 is connected to the hydraulic oil tank 15, but the discharge destination of the hydraulic oil is not limited to the hydraulic oil tank 15, and may be a suction part of a hydraulic pump, or in other places There may be no limitation.

DESCRIPTION OF SYMBOLS 1 Work implement 19c 1st check valve 20 Control valve 21 1st oil path (1st communication path)
22 Second oil passage (second communication passage)
23 Third oil passage (main oil passage)
24 4th oil passage (exhaust oil passage)
24b Second discharge oil passage 25 Fifth oil passage (supply oil passage)
28 Oil cooler 31 1st port 32 2nd port 33 3rd port 34 4th port 35 5th port 41 1st internal oil path 42 2nd internal oil path 43 3rd internal oil path 44 4th internal oil path 45 5th Internal oil passage 50 Spool 51 First communication portion 51a First extension oil passage 51b Second extension oil passage 51c Third extension oil passage 52 Second communication portion 61a First connection oil passage 61b Second connection oil passage 65a First 1 branch flow path 65b 2nd branch flow path 67a 1st throttle part 67b 2nd throttle part 67c throttle 67d throttle 67e throttle B1 body P1 1st hydraulic pump P2 2nd hydraulic pump

Claims (15)

A hydraulic pump that discharges hydraulic oil;
A first hydraulic device actuated by hydraulic oil;
A second hydraulic device operated by hydraulic oil and different from the first hydraulic device;
A first control valve for controlling the first hydraulic device;
A second control valve that is provided downstream of the first control valve and controls the second hydraulic device;
A communication path that connects the first hydraulic device and the first control valve and flows return oil that is hydraulic oil that returns from the first hydraulic device to the first control valve;
A supply oil path connecting the first control valve and the second control valve and supplying the return oil to the second control valve;
A connection oil passage provided in the first control valve and connecting the communication passage and the supply oil passage;
A drain oil passage connected to the first control valve;
A setting unit that is provided in the discharge oil passage and increases the pressure of the discharge oil passage;
A branch flow path branched from the connection oil path and connected to the discharge oil path;
A throttle provided in the branch channel;
The working machine's hydraulic system. The first hydraulic device is a hydraulic cylinder that expands and contracts,
The communication path is
A first communication path through which return oil during contraction flows;
A second communication path through which return oil during extension flows;
Including
The connection oil passage communicates with the second communication passage and the return oil discharged from the second communication passage flows.
2. The hydraulic system for a working machine according to claim 1, wherein the supply oil passage supplies the return oil communicated from the connection oil passage and discharged from the connection oil passage to the second control valve. A discharge oil passage for supplying hydraulic oil discharged from the hydraulic pump to the first control valve and the second control valve;
The drain oil passage is
A first drain oil passage connected to the first control valve;
A second discharge oil passage communicating from the discharge oil passage and joining the first discharge oil passage;
A third drain oil passage communicating with the discharge oil passage;
The working system hydraulic system according to claim 1, comprising:   4. The hydraulic system for a working machine according to claim 3, wherein the setting unit includes an operation valve that is provided in the third discharge oil passage and raises a pressure of the third discharge oil passage. 5.   The working valve allows a working oil from the second discharged oil passage to the third discharged oil passage, and prevents a working oil from the third discharged oil passage to the second discharged oil passage. The hydraulic system for a working machine according to claim 4, wherein the hydraulic system is a valve.   The hydraulic system for a working machine according to claim 4 or 5, wherein the setting unit includes an oil cooler that cools the hydraulic oil discharged from the first discharge oil passage.   4. The hydraulic system for a working machine according to claim 3, wherein the setting unit is provided in the discharge oil passage and includes any one of an oil cooler, a check valve, a throttle, and a relief valve.   The hydraulic system for a working machine according to claim 3, wherein the setting unit is a throttle provided in the discharged oil passage. A hydraulic pump that discharges hydraulic oil;
A first hydraulic device actuated by hydraulic oil;
A second hydraulic device operated by hydraulic oil and different from the first hydraulic device;
A first control valve for controlling the first hydraulic device;
A second control valve that is provided downstream of the first control valve and controls the second hydraulic device;
A first communication passage that connects the first hydraulic device and the first control valve, and flows return oil that is hydraulic oil that returns from the first hydraulic device to the first control valve;
A second communication passage that connects the first hydraulic device and the first control valve, flows return oil that returns from the first hydraulic device to the first control valve, and is different from the first communication passage;
A supply oil path connecting the first control valve and the second control valve and supplying the return oil to the second control valve;
A first connection oil passage provided in the first control valve and connecting the first communication passage and the supply oil passage;
A second connection oil passage that is provided in the first control valve, connects the second communication passage and the supply oil passage, and is different from the first connection oil passage;
A drain oil passage connected to the first control valve;
A first branch passage branched from the first connection oil passage and connected to the discharge oil passage;
A second branch flow path branched from the second connection oil path and connected to the discharge oil path;
A first throttle portion provided in the first branch channel;
A second throttle part provided in the second branch channel and smaller than the first throttle part;
The working machine's hydraulic system. The first hydraulic device is a hydraulic cylinder that expands and contracts, discharges return oil when contracted to the first communication path, and discharges return oil when extended to the second communication path;
The first connecting oil passage communicates with the first communication passage and the return oil discharged from the first communication passage flows.
The supply oil passage communicates from the first connection oil passage and supplies the return oil discharged from the first connection oil passage to the second control valve,
The second connection oil passage communicates with the second communication passage and the return oil discharged from the second communication passage flows.
10. The hydraulic system for a work machine according to claim 9, wherein the supply oil passage supplies the return oil communicated from the second connection oil passage and discharged from the second connection oil passage to the second control valve.   The second check valve that is provided in the discharge oil passage and that allows the hydraulic oil discharged from the first control valve and blocks the hydraulic oil toward the first control valve. The hydraulic system for a work machine according to 10, wherein A first port to which a first oil passage connected to the first hydraulic device is connected, a second port to which a second oil passage connected to the first hydraulic device is connected, and a hydraulic pump that discharges hydraulic oil A third port to which a third oil passage connected to the second port is connected; a fourth port to which a first discharge oil passage for discharging hydraulic oil is connected; and hydraulic oil that has passed through the first port or the second port. A fifth port that discharges to the outside, a first port, a second port, a third port, a fourth port, a first internal oil passage connected to the fifth port, a second internal oil passage, a third internal oil passage, A main body having a fourth internal oil passage and a fifth internal oil passage;
The communication destination of the first internal oil passage, the second internal oil passage, the third internal oil passage, the fourth internal oil passage, and the fifth internal oil passage can be changed by moving the inside of the main body, and the first A spool that can move to a neutral position and a communication position where the two internal oil passages communicate with the fifth internal oil passage or the first internal oil passage communicates with the fifth internal oil passage;
The spool communicates between the second internal oil passage and the fourth internal oil passage or the first internal oil passage and the fourth internal oil passage when the spool is between the communication position and the neutral position. A control valve having one communicating portion.   The control valve according to claim 12, wherein the spool communicates the second internal oil passage and the fifth internal oil passage when the first internal oil passage and the third internal oil passage communicate with each other. .   The first communication portion includes a first extending oil passage extending in a longitudinal direction of the spool, a plurality of second extending oil passages extending from one end of the first extending oil passage to an outer peripheral surface of the spool, The control valve according to claim 12 or 13, comprising a plurality of third extending oil passages extending from an intermediate portion of the first extending oil passage to the outer peripheral surface of the spool. The spool has a second communication portion capable of communicating the first internal oil passage and the third internal oil passage,
The control valve according to any one of claims 12 to 14, wherein the second communication portion is a recess formed in an outer peripheral surface of the spool.

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