JP2020008171A - Hydraulic system for working machine - Google Patents

Abstract

To provide a hydraulic system for a working machine that can warm up fluid tubes in a simple manner by means of a brake-operation valve and a traveling operation valve.SOLUTION: The hydraulic system for a working machine includes: a hydraulic pump to output operation fluid; a braking mechanism to brake a traveling device and release braking of the traveling device on the basis of pressure of operation fluid; a traveling pump to drive the traveling device on the basis of pressure of operation fluid; a brake-operation valve to control operation fluid supplying to the braking mechanism; a traveling operation valve to control operation fluid supplying to the traveling pump; a first fluid tube connecting the brake mechanism and the brake-operation valve; a second fluid tube connecting the traveling pump and the traveling operation valve; a third fluid tube connecting the first fluid tube and the second fluid tube; a first discharge fluid tube connected to the brake operation valve to discharge the operation fluid flowing through the brake-operation valve; and a second discharge fluid tube connected to the traveling operation valve to discharge the operation fluid flowing through the traveling operation valve. The traveling operation valve is set to be a pressure higher than a brake set pressure set by the brake operation valve.SELECTED DRAWING: Figure 1

Description

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

2. Description of the Related Art Conventionally, there is a technique disclosed in Patent Document 1 as a technique for warming up a working machine.
The work machine disclosed in Patent Document 1 includes a pilot pressure control valve that controls the pressure of pilot oil discharged from a pump and sent to a supply target, and a valve body in which the pilot pressure control valve is incorporated. In Patent Literature 1, a heat-up oil passage that allows pilot oil discharged from a pump to flow into a valve body is provided, and the pilot oil that flows into the heat-up oil passage flows into a hydraulic oil tank via a relief valve or a throttle. This heats up the valve body.

Japanese Patent No. 5809544

In the working machine of Patent Literature 1, the valve body must be machined for warming up, and a hydraulic oil path connecting the relief valve or the throttle must be formed in the valve body.
The present invention has been made in order to solve such problems of the related art, and provides a working machine hydraulic system that can easily warm up an oil passage by a brake operating valve and a traveling operating valve. Aim.

The technical measures taken by the present invention to solve the technical problem are as follows.
The hydraulic system of the working machine includes a hydraulic pump that discharges hydraulic oil, a brake mechanism that performs braking of the traveling device based on the pressure of the hydraulic oil, and releases the braking, and the traveling device that is based on the pressure of the hydraulic oil. A traveling pump to be driven, a brake actuation valve for controlling hydraulic oil supplied to the brake mechanism, a traveling actuation valve for controlling hydraulic oil supplied to the traveling pump, and the brake mechanism and the brake actuation valve are connected. A first oil passage, a second oil passage connecting the traveling pump and the traveling actuation valve, a third oil passage connecting the first oil passage and the second oil passage, and a brake actuation valve. A first discharge oil passage communicating with and discharging the hydraulic oil passing through the brake operation valve, and a second discharge oil passage communicating with the travel operation valve and discharging hydraulic oil passing through the travel operation valve. The travel operating valve, Serial set to a pressure higher than the brake set pressure set by the brake actuation valve.

The brake actuating valve is a brake switching valve that can be switched between a first position where the brake mechanism sets the braking pressure at which the braking is performed and a second position where the brake mechanism sets the release pressure.
The brake actuating valve is a brake proportional valve that is variable from a braking pressure at which the brake mechanism performs the braking to the release pressure.
The second oil passage is provided with an operation valve capable of changing a pressure for supplying hydraulic oil to the traveling pump in accordance with an operation, and the third oil passage is connected to the traveling operation valve in the second oil passage. It is connected to the section with the operation valve.

The second oil passage is provided with an operation valve capable of changing a pressure for supplying hydraulic oil to the traveling pump in accordance with an operation, and the third oil passage is provided in the second oil passage with the operation valve. The traveling operation valve is connected to a section of the traveling pump, and is provided on the second oil passage at an upstream side of the operation valve.
The travel operating valve is an anti-stall proportional valve that changes the pressure of hydraulic oil to the hydraulic pump based on the rotation speed of a prime mover, or a hydraulic lock switching valve that can stop supply of hydraulic oil to the operating valve. is there.

A check valve that is provided in the third oil passage and that allows hydraulic oil from the second oil passage to the first oil passage and that blocks hydraulic oil from the first oil passage to the second oil passage; It has.
The hydraulic system of the work machine includes: a traveling motor operable by hydraulic oil discharged from the traveling pump; and a shift oil passage that connects the traveling motor and the traveling pump. The traveling operation valve includes a regulator that can operate the swash plate, and the traveling operation valve switches the traveling pump to one of forward rotation and reverse rotation by operating the swash plate with the regulator.

  According to the present invention, the oil passage can be easily warmed up by the brake operation valve and the traveling operation valve.

It is a figure showing a hydraulic system (hydraulic oilway) of a work machine in a 1st embodiment. It is the elements on larger scale of the hydraulic system of the traveling system of a working machine. It is a figure which shows the 1st modification of FIG. 2A. It is a figure which shows the 2nd modification of FIG. 2B. It is the 3rd modification which changed the connection destination of the 3rd oilway. FIG. 3 is a diagram illustrating a relationship between an engine speed and a traveling primary pressure. It is a figure showing a hydraulic system (hydraulic oilway) of a work machine in a 2nd embodiment. It is a figure showing a hydraulic system (hydraulic oilway) of a work machine in a 3rd embodiment. It is a figure showing a hydraulic system (hydraulic oilway) of a work machine in a 4th embodiment. It is a figure showing a hydraulic system (hydraulic oilway) of a work machine in a 5th embodiment. It is a figure which shows the modification of the hydraulic system of the working machine in 5th Embodiment. It is a side view which shows the track loader which is an example of a working machine.

Hereinafter, an embodiment of a hydraulic system of the work machine 1 according to the present invention will be described with reference to the drawings as appropriate.
[First Embodiment]
FIG. 10 shows a side view of the working machine 1 according to the present invention. FIG. 10 shows a compact truck loader as an example of the work machine 1. However, the working machine 1 according to the present invention is not limited to a compact truck loader, and may be another type of loader working machine such as a skid steer loader. Further, the work machine 1 other than the loader work machine may be used.

As shown in FIG. 10, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a traveling device 5.
In the embodiment of the present invention, the front side (left side in FIG. 10) of the driver sitting on the driver's seat 8 of the work machine 1 is forward, the rear side (right side in FIG. 10) is rearward, and the left side of the driver (FIG. 10 is described as a left side, and the right side of the driver (a back side in FIG. 10) is described as a right side. In addition, a horizontal direction that is a direction orthogonal to the front and rear directions will be described as a body width direction. The direction from the center of the body 2 to the right or left will be described as the outside of the body. In other words, the outside of the body is the direction of the body width and the direction away from the body 2. The direction opposite to the outside of the body will be described as the inside of the body. In other words, the inside of the airframe is the width direction of the airframe and the direction approaching the airframe 2.

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

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

The lift link 12, the control link 13, and the boom cylinder 14 are provided on the left and right sides of the body 2 corresponding to the left and right booms 10, respectively.
The lift link 12 is provided at the rear of the base of each boom 10 in a vertical direction. The upper part (one end side) of the lift link 12 is rotatably supported around a horizontal axis via a pivot 16 (first pivot) near a rear portion of the base of each boom 10. Further, a lower portion (the other end side) of the lift link 12 is rotatably supported around a horizontal axis via a pivot shaft 17 (second pivot shaft) near a rear portion of the body 2. The second pivot 17 is provided below the first pivot 16.

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

  The control link 13 is provided in front of the lift link 12. One end of the control link 13 is rotatably supported around a horizontal axis via a pivot 20 (fifth pivot). The fifth pivot 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 rotatably supported around a horizontal axis via a pivot 21 (sixth pivot). The sixth pivot 21 is the boom 10 and is provided in front of the second pivot 17 and above the second pivot 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. Goes up and down. The control link 13 swings up and down around the fifth pivot 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the second pivot 17 with the vertical swing of the control link 13.

At the front of the boom 10, another work tool 11 can be mounted instead of the bucket 11. As another working tool 11, there 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, a snow blower, and the like.
A connection member 50 is provided at a front portion of the left boom 10. The connection member 50 is a device that connects a hydraulic device mounted on the preliminary attachment and a first pipe material such as a pipe provided on the boom 10. Specifically, a first pipe member can be connected to one end of the connection member 50, and a second pipe member connected to a hydraulic device of the spare attachment can be connected to the other end. Thereby, the hydraulic oil flowing through the first pipe material is supplied to the hydraulic equipment through the second pipe material.

The bucket cylinders 15 are respectively arranged near the front portions of the respective booms 10. The bucket 11 is swung by expanding and contracting the bucket cylinder 15.
In the present embodiment, the traveling devices 5 of the crawler type (including the semi-crawler type) are adopted as the traveling devices 5 on the left and right sides. Note that a wheel-type traveling device 5 having a front wheel and a rear wheel may be employed.

Next, a hydraulic system of the work machine 1 according to the present invention will be described. The hydraulic system of the working machine 1 has a traveling hydraulic system and a working hydraulic system.
As shown in FIG. 1, the traveling-system hydraulic system is a traveling-system hydraulic system that drives the traveling device 5, and includes a motor 32, a first hydraulic pump (hydraulic pump) P <b> 1, and a first traveling system. A motor mechanism 31L, a second traveling motor mechanism 31R, and a traveling drive circuit 34 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 driven by the power of the prime mover 32, and is configured by a constant displacement gear pump. The first hydraulic pump P1 can discharge hydraulic oil stored in a tank (hydraulic oil tank) 22. On the discharge side of the first hydraulic pump P1, a discharge oil passage 40 through which hydraulic oil flows is provided. A filter 35 is provided in the middle of the discharge oil passage 40. The discharge side of the hydraulic oil in the discharge oil passage 40 is branched into a plurality. A first charge oil passage 41 is connected to the discharge side of the discharge oil passage 40. The first charge oil passage 41 reaches the traveling drive mechanism 34. Of the hydraulic oil discharged from the first hydraulic pump P1, hydraulic oil used for control may be referred to as pilot oil, and pressure of the pilot oil may be referred to as pilot pressure.

The traveling drive mechanism 34 is a mechanism that drives the first traveling motor mechanism 31L and the second traveling motor mechanism 31R, and includes a driving circuit (left driving circuit) 34L for driving the first traveling motor mechanism 31L and a second traveling motor. And a drive circuit (right drive circuit) 34R for driving the motor mechanism 31R.
The drive circuits 34L and 34R have HST pumps (traveling pumps) 52L and 52R, shift oil passages 57h and 57i, and a second charge oil passage 42, respectively. The shift oil passages 57h and 57i are oil passages connecting the HST pumps 52L and 52R and the HST motor 36. The second charge oil passage 42 is connected to the shift oil passages 57h and 57i, and is an oil passage for replenishing the hydraulic oil from the first hydraulic pump P1 to the shift oil passages 57h and 57i. The HST pumps 52L and 52R are swash plate type variable displacement axial pumps driven by the power of the prime mover 32. Each of the HST pumps 52L and 52R has a forward pressure receiving portion 52a and a reverse pressure receiving portion 52b on which pilot pressure acts, and the angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 52a and 52b. The output of the HST pumps 52L and 52R (discharge amount of hydraulic oil) and the discharge direction of hydraulic oil can be changed by changing the angle of the swash plate. In other words, the HST pumps 52L and 52R change the driving force output to the traveling device 5 by changing the angle of the swash plate.

The first traveling motor mechanism 31L is a mechanism that transmits power to a drive shaft of the traveling device 5 provided on the left side of the body 2. The second traveling motor mechanism 31R is a mechanism that transmits power to a drive shaft of the traveling device 5 provided on the right side of the body 2. The first travel motor mechanism 31L has an HST motor (travel motor) 36 and a speed change mechanism.
The HST motor 36 is a swash plate type variable displacement axial motor that can change the vehicle speed (rotation) to first speed or second speed. In other words, the HST motor 36 is a motor that can change the propulsion force of the work implement 1.

  The transmission mechanism includes a swash plate switching cylinder 38a and a switching valve 38b. The swash plate switching cylinder 38a is a cylinder that changes the angle of the swash plate of the HST motor 36 by expansion and contraction. The switching valve 38b is a valve that expands and contracts the swash plate switching cylinder 38a to one side or the other side, and is a two-position switching valve that switches between a first position 39a and a second position 39b. The switching of the switching valve 38 b is performed by the shift switching valve 33. The speed changeover switching valve 33 is connected to the discharge oil passage 40 and is connected to the switching valve 38b of the first traveling motor mechanism 31L and the switching valve 38b of the second traveling motor mechanism 31R. The shift switching valve 33 is a two-position switching valve that can switch between a first position 33a and a second position 33b. When the shift switching valve 33 is set to the first position 33a, the pressure of the operating oil acting on the switching valve 38b is set to a pressure (deceleration pressure) corresponding to a predetermined speed (for example, first speed). When the shift switching valve 33 is set to the second position 33b, the pressure of the hydraulic oil applied to the switching valve 38b is increased to a pressure (increased pressure) corresponding to the speed (second speed) faster than a predetermined speed (first speed). Set. Therefore, when the shift switching valve 33 is at the first position 33a, the switching valve 38b is at the first position 39a, and accordingly, the swash plate switching cylinder 38a is contracted, and the HST motor 36 can be set to the first speed. . When the shift switching valve 33 is at the second position 33b, the switching valve 38b is at the second position 39b. Accordingly, the swash plate switching cylinder 38a is extended, and the HST motor 36 can be set to the second speed. . The HST motor 36 shifts to the first speed or the second speed under the control of the control device 90. For example, the control device 90 is provided with an operation member 58 such as a switch (speed change switch). When the operating member 58 is switched to the first speed, the control device 90 outputs a control signal for demagnetizing the solenoid of the shift switching valve 33 to set the shift switching valve 33 to the first position 33a. When the operating member 58 is switched to the second speed, the control device 90 outputs a control signal for exciting the solenoid of the shift switching valve 33 to set the shift switching valve 33 to the second position 33b.

  The first traveling motor mechanism 31L has a brake mechanism 30. The brake mechanism 30 can stop the braking of the traveling device 5 on the right side, that is, the rotation of the HST motor 36 or the rotation of the output shaft that rotates with the rotation of the HST motor 36. The brake mechanism 30 changes to an operation state of braking the traveling motor mechanism 31 or an operation state of releasing the braking by the pilot oil (hydraulic oil) discharged from the first hydraulic pump P1. For example, the brake mechanism 30 includes a first disk provided on an output shaft of the traveling motor mechanism 31, a movable second disk, and a spring for urging the second disk to contact the first disk. ing. Further, the brake mechanism 30 includes a housing portion (housing case) 59 for housing the first disk, the second disk, and the spring. The portion of the housing portion 59 in which the second disk is stored and the brake switching valve 80a are connected via an oil passage as described later. The brake switching valve 80a is an electromagnetic valve that performs braking and release of braking (braking release) in the brake mechanism 30, and is a two-position switching valve that can be switched between a first position 80a1 and a second position 80a2. When in the first position 80a1, the brake switching valve 80a sets the pressure of the hydraulic oil applied to the brake mechanism 30 (the pressure applied to the storage portion 59) to the pressure (braking pressure) at which the brake mechanism 30 performs braking. When the brake switching valve 80a is at the second position 80a2, the pressure of the hydraulic oil is set to be equal to or higher than the pressure at which the brake is released (release pressure). The switching of the brake switching valve 80a is performed under the control of the control device 90. For example, the control device 90 outputs a control signal for demagnetizing the solenoid of the brake switching valve 80a to set the brake switching valve 80a to the first position 80a1. Further, the control device 90 outputs a control signal for exciting the solenoid of the brake switching valve 80a to set the brake switching valve 80a to the second position 80a2. In addition, the output of the control signal from the control device 90 to the brake switching valve 80a may be performed, for example, by providing a switch and manually operating the switch. The judgment may be made automatically.

  Therefore, when the brake control switching valve 80a is at the first position 80a1, the pilot oil in the storage section of the storage section 59 is discharged, the second disk moves in the direction of braking, and braking by the brake mechanism 30 can be performed. When the brake control switching valve 80a is at the second position 80a2, the pilot oil is supplied to the storage portion of the storage portion 59, and the second disk is turned on the opposite side to braking (opposite to the biasing direction of the spring). Movement and release of braking in the brake mechanism 30 can be performed. The second traveling motor mechanism 31R has the same configuration as the first traveling motor mechanism 31L, and the configuration shown by the first traveling motor mechanism 31L may be replaced with the second traveling motor mechanism 31R. Description is omitted.

As shown in FIG. 1, the work machine 1 includes an operation device 53. The operating device 53 is a device that operates the traveling device 5, that is, the first traveling motor mechanism 31L, the second traveling motor mechanism 31R, and the traveling driving mechanism 34. The operating device 53 has a first operating member 54 and a plurality of operating valves 55 (55a, 55b, 55c, 55d).
The first operating member 54 is an operating member that is supported by the operating valve 55 and swings in the left-right direction (machine body width direction) or the front-back direction. Further, the plurality of operation valves 55 are operated in common, that is, by one first operation member 54. The plurality of operation valves 55 operate based on the swing of the first operation member 54. Hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied to the plurality of operation valves 55 via the discharge oil passage 40. The plurality of operation valves 55 are an operation valve 55a, an operation valve 55b, an operation valve 55c, and an operation valve 55d.

  The plurality of operation valves 55 and the travel drive mechanism 34 (travel pumps 52L and 52R) of the travel system are connected by a travel oil path 45. The traveling oil passage 45 has a first traveling oil passage 45a, a second traveling oil passage 45b, a third traveling oil passage 45c, a fourth traveling oil passage 45d, and a fifth traveling oil passage 45e. The first traveling oil passage 45a is an oil passage connected to the forward pressure receiving portion 52a of the traveling pump 52L. The second traveling oil passage 45b is an oil passage connected to the reverse pressure receiving portion 52b of the traveling pump 52L. The third traveling oil passage 45c is an oil passage connected to the forward pressure receiving portion 52a of the traveling pump 52R. The fourth traveling oil passage 45d is an oil passage connected to the reverse pressure receiving portion 52b of the traveling pump 52R. The fifth traveling oil passage 45e is an oil passage connecting the operation valve 55, the first traveling oil passage 45a, the second traveling oil passage 45b, the third traveling oil passage 45c, and the fourth traveling oil passage 45d. The fifth traveling oil passage 45e connects the plurality of shuttle valves 46 and the plurality of operation valves 55 (55a, 55b, 55c, 55d).

  When the first operating member 54 is swung forward (in the direction indicated by the arrow A1 in FIG. 1), the operating valve 55a is operated, and the pilot pressure is output from the operating valve 55a. The work implement 1 rotates forward (rotation forward) at a speed proportional to the swing amount of the member 54, and the work machine 1 moves straight forward. When the first operating member 54 is swung rearward (in the direction indicated by the arrow A2 in FIG. 1), the operating valve 55b is operated and the pilot pressure is output from the operating valve 55b, and the output shaft of the traveling motor 36 is moved to the second position. The reverse rotation (reverse rotation) at a speed proportional to the swing amount of the one operation member 54 causes the work machine 1 to move straight back.

  When the first operation member 54 is swung to the right (in the direction indicated by the arrow A3 in FIG. 1), the operation valve 55c is operated, and the pilot pressure is output from the operation valve 55c. The shaft rotates forward and the output shaft of the traveling motor 36 on the right rotates reversely, and the work machine 1 turns to the right. When the first operating member 54 is swung to the left (in the direction indicated by the arrow A4 in FIG. 1), the operating valve 55d is operated, the pilot pressure is output from the operating valve 55d, and the output shaft of the left traveling motor 36 is driven. The work machine 1 rotates in the reverse direction and the output shaft of the traveling motor 36 on the right rotates forward, and the work machine 1 turns to the left.

When the first operation member 54 is swung in an oblique direction, the output pressure of the left traveling motor 36 and the output shaft of the right traveling motor 36 are increased by the differential pressure between the pilot pressure acting on the pressure receiving portion 52a and the pressure receiving portion 52b. The rotation direction and the rotation speed are determined, and the work machine 1 turns right or left while moving forward or backward.
As shown in FIG. 1, a hydraulic lock switching valve 81a capable of stopping hydraulic oil supplied to the operation device 53 (operation valves 55a, 55b, 55c, and 55d) is connected to the discharge oil passage 40. The hydraulic lock switching valve 81a is a two-position switching valve that can be switched between a first position 81a1 and a second position 81a2. When the hydraulic lock switching valve 81a is set to the first position 81a1, the pilot oil from the first hydraulic pump P1 is not supplied to the operation valves 55a, 55b, 55c, and 55d. The lock state is established in which the pressure of the hydraulic oil by the valves 55a, 55b, 55c, and 55d does not act on the HST pumps (traveling pumps) 52L and 52R. When the hydraulic lock switching valve 81a is set to the second position 81a2, the pilot oil from the first hydraulic pump P1 is supplied to the operation valves 55a, 55b, 55c, and 55d, and is operated in accordance with the operation of the first operation member 54. The pressure of the hydraulic oil by the valves 55a, 55b, 55c, and 55d is in an unlocked state in which the pressure acts on the HST pumps (traveling pumps) 52L and 52R.

  Now, the hydraulic system of the work machine 1 connects the first hydraulic path connected to the first hydraulic apparatus and the second hydraulic path connected to the second hydraulic apparatus by the third hydraulic path, and supplies the first hydraulic apparatus to the first hydraulic apparatus. By connecting the first discharge oil passage to the first hydraulic valve that controls the hydraulic oil to be activated, and by connecting the second discharge oil passage to the second hydraulic valve that controls the hydraulic oil supplied to the second hydraulic device, It is easy to warm up. In this embodiment, the first hydraulic device is the brake mechanism 30, and the second hydraulic device is the traveling drive mechanism 34. Further, the first operating valve is one of the brake operating valves that controls the operating oil supplied to the brake mechanism 30, and the second operating valve controls the operating oil supplied to the traveling drive mechanism 34. This is a hydraulic lock switching valve 81a which is one of the traveling operation valves.

Hereinafter, the first oil passage, the second oil passage, and the third oil passage will be described.
As shown in FIGS. 1 and 2A, the first oil passage 61 is provided with a first hydraulic device (brake mechanism 30) and a first operating valve (hydraulic oil) that controls hydraulic oil supplied to the first hydraulic device (brake mechanism 30). Brake switching valve) 80a. In this embodiment, the first oil passage 61 includes a first brake oil passage 61a and a second brake oil passage 61b. The first brake oil passage 61a is an oil passage that connects the brake mechanism 30 of the first traveling motor mechanism 31L and the brake switching valve (first operating valve) 80a. The second brake oil passage 61b is an oil passage that connects the brake mechanism 30 of the second traveling motor mechanism 31R and the brake switching valve (first operating valve) 80a. The first brake oil passage 61a and the second brake oil passage 61b merge on the way, and the merged oil passage (combined oil passage for the first brake oil passage 61a and the second brake oil passage 61b) 61c is braked. It is connected to the switching valve 80a. A throttle portion 74 for reducing the flow rate of hydraulic oil is provided in the dual-purpose oil passage 61c. In other words, in the first oil passage 61, the constricted portion 74 is formed by a connection (a junction 64 described later) where the third oil passage 63 is connected to the first oil passage 61 and a connection that is connected to the brake switching valve 80 a. It is provided in the section.

A first discharge oil passage 66 is connected to a discharge port of the brake switching valve 80a. The first discharge oil passage 66 can discharge the hydraulic oil that has passed through the brake switching valve 80a, that is, the hydraulic oil of the first oil passage 61 (the first brake oil passage 61a and the second brake oil passage 61b). The first discharge oil passage 66 is connected to a suction portion of a hydraulic pump, the hydraulic oil tank 22, and the like.
The second oil passage 62 controls hydraulic oil supplied to the second hydraulic equipment (the travel pumps 52L and 52R of the travel drive mechanism 34) and the second hydraulic equipment (the travel pumps 52L and 52R of the travel drive mechanism 34). This is an oil passage connecting the two-operation valve (hydraulic lock switching valve) 81a. In this embodiment, the second oil passage 62 includes a section (oil passage) 40a connecting the hydraulic lock switching valve 81a and the operation valves 55a, 55b, 55c, 55d in the discharge oil passage 40, and the operation valves 55a, 55b, A traveling oil passage 45 connecting the traveling pumps 52L, 52R to the traveling pumps 52L, 52R is included.

A second discharge oil passage 67 is connected to a discharge port of the hydraulic lock switching valve 81a. The second discharge oil passage 67 can discharge the hydraulic oil that has passed through the hydraulic lock switching valve 81a, that is, the hydraulic oil in the second oil passage 62. The second discharge oil passage 67 is connected to a suction portion of the hydraulic pump, the hydraulic oil tank 22, and the like.
The third oil passage 63 is an oil passage that connects the first oil passage 61 and the second oil passage 62. The third oil passage 63 connects a junction 64 where the first brake oil passage 61a and the second brake oil passage 61b join, and a junction 65 where the oil passage 40a joins. The third oil passage 63 is connected to the discharge oil passage 40 on the upstream side of the operation valves 55a, 55b, 55c, and 55d. That is, the third oil passage 63 is connected to the primary side of the operation valves 55a, 55b, 55c, and 55d. Further, a check valve 173 is connected to the third oil passage 63. The check valve 173 allows hydraulic oil from the second oil passage 62 to the first oil passage 61 and blocks hydraulic oil from the first oil passage 61 to the second oil passage 62.

As shown in FIGS. 1 and 2A, a throttle portion 84 is provided in the oil passage 40a between the junction 65 and the second operating valve (hydraulic lock switching valve) 81a. The throttle portion 84 may be provided in the discharge oil passage 40 on the upstream side of the second operating valve (hydraulic lock switching valve) 81a.
The control device 90 includes a brake set pressure (first set pressure) PV1 set by a brake switching valve (first operating valve) 80a and a set pressure (second set pressure) set by a second operating valve (hydraulic lock switching valve) 81a. 2 Set pressure) Set the pressure difference from PV2. The brake set pressure PV1 is, for example, the pressure at the output port 100 of the brake switching valve 80a. In other words, the first set pressure PV1 is a pressure acting on the first oil passage 61 (the first brake oil passage 61a and the second brake oil passage 61b).

The second set pressure (set pressure) PV2 is, for example, the pressure at the output port 101 of the hydraulic lock switching valve 81a. In other words, the second set pressure PV2 is a pressure acting on the second oil passage 62.
The control device 90 controls the brake switching valve 80a and the hydraulic lock switching valve 81a such that a differential pressure between the first set pressure PV1 and the second set pressure PV2 is generated. The control device 90 sets the brake set pressure PV1 of the brake switching valve 80a lower than the set pressure PV2 of the hydraulic lock switching valve 81a, for example, in a warm-up mode for performing warm-up. In other words, when in the warm-up mode, the control device 90 sets the set pressure PV2 of the hydraulic lock switching valve 81a higher than the brake set pressure PV1 of the brake switching valve 80a.

  Specifically, in the warm-up mode, the control device 90 sets the brake set pressure PV1 to the braking pressure at which the brake mechanism 30 brakes by setting the brake switching valve 80a to the first position 80a1. Further, in the warm-up mode, the control device 90 sets the hydraulic pressure lock switching valve 81a to the second position 81a2 so that the set pressure PV2 is higher than the brake set pressure PV1. That is, when the brake switching valve 80a is in the braking state and the hydraulic lock switching valve 81a is in the unlocked state, the brake set pressure PV1 <the set pressure PV2, and the set pressure PV2 set by the hydraulic lock switch valve 81a is Becomes higher than the brake set pressure PV1 of the hydraulic oil set by the brake switching valve 80a.

  As shown by an arrow A10 in FIG. 2A, when the brake set pressure PV1 <the set pressure PV2, the hydraulic oil that has passed through the hydraulic lock switching valve 81a passes through the second oil passage 62 and the third oil passage 63, and then enters the first oil passage. The oil flows into the oil passage 61 and is discharged from the discharge port of the brake switching valve 80a to the first discharge oil passage 66. This makes it possible to warm up the first oil passage (brake oil passage) and the second oil passage (travel oil passage). In the warming-up mode, for example, a mode switch 95 that can be switched ON / OFF is connected to the control device 90. When the mode switch 95 is ON, the warming-up mode is set and the mode switch 95 is turned OFF. If, the warm-up mode is canceled.

FIG. 2B is a diagram showing a first modification of FIG. 2A. 2B shows the oil passage on the first traveling motor mechanism 31L side for convenience of explanation, but the oil passage on the second traveling motor mechanism 31R side is omitted, and the oil passage on the second traveling motor mechanism 31R side is omitted. It is also applicable to oil passages.
As shown in FIG. 2B, the first modified example is an example in which the second operating valve is changed to an anti-stall proportional valve 81b constituted by an electromagnetic proportional valve.

  The anti-stall proportional valve 81b performs control for preventing engine stall (anti-stall control). FIG. 4 shows the relationship between the engine speed, the traveling primary pressure, and the control lines L1 and L2. The traveling primary pressure is a pressure (pilot pressure) of hydraulic oil in a section from the anti-stall proportional valve 81b to the operation valve 55 (the operation valve 55a, the operation valve 55b, the operation valve 55c, and the operation valve 55d) in the discharge oil passage 40. It is. That is, it is the primary pressure of the hydraulic oil entering the operation valve 55 provided on the operation member 54. The control line L1 indicates the relationship between the engine speed and the traveling primary pressure when the drop amount is less than the predetermined value. The control line L2 indicates the relationship between the engine speed and the traveling primary pressure when the drop amount is equal to or more than a predetermined value.

  When the drop amount is less than the predetermined value, control device 90 adjusts the opening degree of anti-stall proportional valve 81b such that the relationship between the actual engine speed and the traveling primary pressure matches control line L1. Further, when the drop amount is equal to or greater than the predetermined value, control device 90 adjusts the opening of anti-stall proportional valve 81b such that the relationship between the actual engine speed and the traveling primary pressure matches control line L2. . In the control line L2, the traveling primary pressure for a predetermined engine speed is lower than the traveling primary pressure of the control line L1. That is, when focusing on the same engine speed, the traveling primary pressure of the control line L2 is lower than the traveling primary pressure of the control line L1. Therefore, by the control based on the control line L2, the pressure (pilot pressure) of the hydraulic oil entering the operation valve 55 is suppressed low. As a result, the swash plate angle of the HST pump (traveling pump) 52 is adjusted, the load acting on the engine is reduced, and engine stall can be prevented. Although FIG. 4 shows one control line L2, a plurality of control lines L2 may be provided. For example, the control line L2 may be set for each engine speed. The control device 90 preferably has data indicating the control lines L1 and L2, or control parameters such as functions.

  The anti-stall proportional valve 81b has a primary port (pump port) 81b1 and a secondary port 81b2. The primary port 81b1 of the anti-stall proportional valve 81b is connected to the discharge oil passage 40. The secondary port 81b2 of the anti-stall proportional valve 81b is connected to the second oil passage 62 (oil passage 40a). The discharge port 81b3 of the anti-stall proportional valve 81b is connected to the hydraulic oil tank 22 via the second discharge oil passage 67. In the anti-stall proportional valve 81b, the second set pressure (set pressure) PV2 is the pressure of the secondary port 81b2.

In the first modification, the control device 90 sets the opening of the anti-stall proportional valve 81b to the maximum while setting the brake switching valve 80a to the first position 80a1 in the warm-up mode. That is, in the warm-up mode, the controller 90 sets the brake set pressure PV1 of the brake switching valve 80a to the brake pressure and sets the anti-stall proportional valve 81b set pressure PV2 to the brake pressure or more.
Therefore, even when the hydraulic lock switching valve 81a is changed to the anti-stall proportional valve 81b, the brake set pressure PV1 <set pressure PV2 can be set by setting the opening degree of the anti-stall proportional valve 81b. . Also in this case, the hydraulic oil that has passed through the anti-stall proportional valve 81b flows through the second oil passage 62 and the third oil passage 63 to the first oil passage 61, and the first oil is discharged from the discharge port of the brake switching valve 80a. It can be discharged to road 66. When not in the warm-up mode, the control device 90 performs anti-stall control based on the engine speed as described above. In the above-described embodiment, the opening degree of the anti-stall proportional valve 81b is maximized, but the opening degree may be set so that the second set pressure (set pressure) PV2 is higher than the brake set pressure PV1.

  FIG. 2C shows a second modification of FIG. 2B. In the second modification, as shown in FIG. 2C, the brake operation valve is changed to an electromagnetic proportional valve (brake proportional valve) 80b. The brake proportional valve 80b has a primary port (pump port) 80b1 and a secondary port 80b2. The primary port 80b1 of the brake proportional valve 80b is connected to the discharge oil passage 40. The secondary port 80b2 of the brake proportional valve 80b is connected to the first oil passage 61. The discharge port 80b3 of the brake proportional valve 80b is connected to the hydraulic oil tank 22 via the first discharge oil passage 66. In the brake proportional valve 80b, the first set pressure PV1 is the pressure of the secondary port 80b2.

  In the second modification, the control device 90 sets the opening degree of the brake proportional valve 80b to a minimum value so that the braking pressure of the brake mechanism 30 is reduced in the warm-up mode, while the anti-stall proportional valve 81b Set the opening of the maximum. That is, in the warm-up mode, the controller 90 sets the brake set pressure PV1 of the brake proportional valve 80b to the braking pressure and sets the set pressure PV2 of the anti-stall proportional valve 81b to the brake pressure or more.

  Therefore, even when the brake switching valve 80a is changed to the brake proportional valve 80b, the brake set pressure PV1 <set pressure PV2 is set by setting the opening degrees of the brake proportional valve 80b and the anti-stall proportional valve 81b. be able to. Also in this case, the hydraulic oil that has passed through the anti-stall proportional valve 81b flows through the second oil passage 62 and the third oil passage 63 to the first oil passage 61, and the first discharge oil is discharged from the discharge port 80b3 of the brake proportional valve 80b. It can be discharged to the oil passage 68.

  FIG. 3 shows a third modification of the third oil passage 63. In the above-described embodiment, the third oil passage 63 is connected to the upstream side (primary side) of the operation valves 55a, 55b, 55c, and 55d. However, in the third modification, the operation valves 55a, 55b, 55c, It is connected to the downstream side (secondary side) of 55d. Note that FIG. 3 shows the operation valves 55a and 55b among the plurality of operation valves 55a, 55b, 55c, and 55d for convenience of description, but the other operation valves 55c and 55d and the operation valves 55c and 55d The connected traveling oil passages 45c and 45d are also applicable.

  The third oil passage 63 includes a first warm-up oil passage 63a and a second warm-up oil passage 63b. The first warm-up oil passage 63a is connected to the first traveling oil passage 45a that forms the second oil passage 62. The second warm-up oil passage 63b is connected to a second traveling oil passage 45b that forms the second oil passage 62. A check valve 173 is connected to the first traveling oil passage 45a and the second traveling oil passage 45b. Also in the third modification, when in the warm-up mode, the control device 90 sets the hydraulic lock switching valve 81a to the unlocked state (unlocking pressure) and sets the brake switching valve 80a to the braking state (braking pressure). By setting, the brake set pressure PV1 <set pressure PV2. Then, the hydraulic oil in the first traveling oil passage 45a and the second traveling oil passage 45b, which is the second oil passage 62, passes through the first warm-up oil passage 63a and the second warm-up oil passage 63b, and the brake switching valve 80a Can be discharged from the discharge port. Although FIG. 3 shows the brake switching valve 80a and the hydraulic lock switching valve 81a, the brake proportional valve 80b and the anti-stall proportional valve 81b may be used as described above.

  In the above-described embodiment, a first measuring device capable of measuring a first set pressure (brake set pressure) PV1 set by a first operating valve, that is, a brake operating valve (a brake switching valve 80a, a brake proportional valve 80b). , A second operating valve, that is, a second measuring device capable of measuring a second set pressure PV2 set by a traveling operating valve (hydraulic lock switching valve 81a, anti-stall proportional valve 81b), and in a warm-up mode. In some cases, the control device 90 may control the first operating valve and the second operating valve such that the brake set pressure PV1 <the set pressure PV2. The control device 90 estimates the first set pressure (brake set pressure) PV1 and the second set pressure (set pressure) PV2 from the drive (discharge pressure, rotation speed, etc.) of the first hydraulic pump P1, the rotation speed of the prime mover, and the like. , The first operating valve and the second operating valve may be controlled.

  Further, the control device 90 is connected to a temperature detecting device 91 for detecting the temperature of the hydraulic oil, and a differential pressure (a difference between the brake set pressure PV1 and the set pressure PV2) is determined according to the detected temperature which is the temperature detected by the temperature detector 91. Differential pressure). Control device 90 increases the differential pressure when the temperature detected by temperature detecting device 91 is lower than a predetermined set temperature. Specifically, the control device 90 increases the opening degree of the anti-stall proportional valve 81b when the detected temperature is below the freezing point and the viscosity of the hydraulic oil is high. The opening of 81b is reduced.

[Second embodiment]
FIG. 5 shows a hydraulic system of a working machine according to the second embodiment. In the second embodiment, as shown in FIG. 5, the first hydraulic device is a work control valve 300, the first operating valve is a hydraulic lock switching valve 310, and the second hydraulic device is a traveling drive mechanism 34 (not shown). The second operating valve is an anti-stall proportional valve 81b.

  The first oil passage connects a first hydraulic device (work control valve 300) and a first hydraulic valve (hydraulic lock switching valve 310) that controls hydraulic oil supplied to the first hydraulic device (work control valve 300). The oil passage 361 is formed. The second oil passage controls a second hydraulic device (the traveling pumps 52L and 52R of the traveling drive mechanism 34) and a second hydraulic device that controls hydraulic oil supplied to the second hydraulic devices (the traveling pumps 52L and 52R of the traveling drive mechanism 34). This is an oil passage 62 for connecting to an operation valve (anti-stall proportional valve 81b). The second oil passage 62 includes a section (oil passage) 40a and a traveling oil passage 45, as in the first embodiment. The third oil passage is an oil passage 363 that connects the first oil passage 361 and the second oil passage 62.

  The work control valve 300 is a valve that controls hydraulic oil supplied to a hydraulic cylinder (work hydraulic actuator) of a work system or the like. The work control valve 300 is, for example, a boom control valve that controls hydraulic oil supplied to the boom cylinder 14, a bucket control valve that controls hydraulic oil supplied to the bucket cylinder 15, and the like. In this embodiment, the operation control valve 300 will be described as a boom control valve, but may be a bucket control valve. For convenience of explanation, the work control valve 300 is described as “boom control valve 300”.

  The boom control valve 300 is, for example, a three-position switching valve. When the boom control valve 300 is operated to one side from the neutral position, the boom control valve 300 supplies hydraulic oil to the bottom side of the boom cylinder 14 while the boom cylinder 14 The boom cylinder 14 is extended by discharging the hydraulic oil discharged from the rod side to a hydraulic oil tank or the like. When the boom control valve 300 is operated to the other side from the neutral position, the boom control valve 300 supplies hydraulic oil to the rod side of the boom cylinder 14 and supplies hydraulic oil discharged from the bottom side of the boom cylinder 14 to a hydraulic oil tank or the like. , The boom cylinder 14 is contracted. The boom control valve 300 is switched by the pressure of the pilot oil (pilot pressure) applied to the pressure receiving portions 300a and 300b provided in the boom control valve 300.

  A working oil passage 320 is connected to each of the pressure receiving portions 300a and 300b of the boom control valve 300. The working oil passage 320 is an oil passage that forms a part of the first oil passage 361. A plurality of operation valves (work operation valves) 330 (330a, 330b) are connected to the work oil passage 320. The plurality of operation valves 330 (330a, 330b) are valves that apply a predetermined pilot pressure to the plurality of working oil passages 320, and change the pilot pressure according to the operation amount of the operation member 331.

  For example, when the operating member 331 is swung in one direction, the operating valve 330a is operated, a pilot pressure is output from the operating valve 330a, and the pilot pressure acts on the pressure receiving portion 300a of the boom control valve 300. When the operating member 331 is swung in the other direction, the operating valve 330b is operated, a pilot pressure is output from the operating valve 330b, and the pilot pressure acts on the pressure receiving portion 300b of the boom control valve 300. That is, by operating the operation member 331, the pilot pressure output from the operation valve 330 changes, and the boom control valve 300, that is, the boom cylinder 14 can be operated.

  The hydraulic lock switching valve 310 is a valve that can stop hydraulic oil supplied to the operation valves 330a and 330b. The hydraulic lock switching valve 310 is a two-position switching valve that can switch between a first position 310a and a second position 310b. When the hydraulic lock switching valve 310 is set to the first position 310a, the pilot oil from the first hydraulic pump P1 does not flow to the first oil passage 361, while the first oil passage 361 is connected to the first discharge oil passage 366. You. That is, when the hydraulic lock switching valve 310 is set to the first position 310a, the pilot oil from the first hydraulic pump P1 is not supplied to the operation valves 330a and 330b, and even if the operation member 331 is operated, the operation valves 330a and 330b Lock state in which the pilot pressure due to does not act on the boom control valve 300. When the hydraulic lock switching valve 310 is set to the second position 310b, the pilot oil from the first hydraulic pump P1 is supplied to the operation valves 330a and 330b, and the pilot pressure acts on the boom control valve 300 when the operation valves 330a and 330b are operated. Unlocked state.

A check valve 373 is connected to the third oil passage 363. The check valve 373 allows the operating oil from the second oil passage 62 to the first oil passage 361 and blocks the operating oil from the first oil passage 361 to the second oil passage 62. In addition, bypass oil passages 374 are provided on both sides of the check valve 373. The bypass oil passage 374 is provided with a throttle 377 that reduces the flow rate of the working oil.
In the second embodiment, when the operation of the first operation member 54 of the traveling system is not performed (when the operation valves 55a and 55b are not operated), the control device 90 can shift to the warm-up mode. Thus, by increasing the opening of the anti-stall proportional valve 81b, the set pressure PV2 of the anti-stall proportional valve 81b is made larger than the pressure (PV1) of the output port 310c of the hydraulic lock switching valve 310. As described above, the control device 90 increases the opening degree of the anti-stall proportional valve 81b at least when the traveling drive mechanism 34 is not operating, so that the operating oil (pilot oil) of the second oil passage 62 After passing through the three oil passages 363, the bypass oil passage 374, and the hydraulic lock switching valve 310, the oil can be discharged from a discharge port of the hydraulic lock switching valve 310 to a first discharge oil passage 366 communicating with a hydraulic oil tank or the like. That is, in the second embodiment, the warm-up can be performed by enabling the hydraulic lock switching valve 310 of the working machine system and the anti-stall proportional valve 81b to communicate with each other through the third oil passage 363.

  In addition, when traveling and work of the work implement 1 are prohibited, that is, in the case of the hydraulic lock mode, the temperature of the pilot oil (the temperature of the hydraulic oil) detected by the temperature detection device 91 is set to a predetermined temperature. The warm-up mode may be set in the following cases. In this case, the hydraulic lock switching valve 310 switches to the first position 310a, while the anti-stall proportional valve 81b increases the predetermined set pressure. When the engine is not in the warm-up mode, the hydraulic lock switching valve 310 is held at the first position 310a, and the anti-stall proportional valve 81b is stopped (communicating the second discharge oil passage 67 with the oil passage 40a).

Also, in a situation other than the set pressure PV2> the set pressure PV1, that is, when the set pressure PV2 of the anti-stall proportional valve 81b becomes lower than the pressure (PV1) of the output port 310c of the hydraulic lock switching valve 310, 2 The pilot oil on the next side may be discharged to the second discharge oil passage 67 through the anti-stall proportional valve 81b.
Specifically, when only traveling of the traveling and work of the work implement 1 is prohibited, that is, in the parking mode, the hydraulic lock switching valve 310 is held at the second position 310b and the anti-stall The proportional valve 81b is stopped. Accordingly, the pilot oil in the first oil passage 361 flows through the bypass oil passage 374 and the oil passage 40a to the second discharge oil passage 67.

  In a mode in which traveling and operation of the work machine 1 are operable, that is, in the operation mode, when the temperature of the pilot oil detected by the temperature detection device 91 becomes equal to or lower than a predetermined temperature, the warm-up is performed. Mode. The hydraulic lock switching valve 310 is held at the second position 310b, and the set pressure PV2 of the anti-stall proportional valve 81b is set lower than the pressure (PV1) of the output port 310c of the hydraulic lock switching valve 310. Thereby, the pilot oil in the first oil passage 361 flows through the bypass oil passage 374 and the second oil passage 62 to the second discharge oil passage 67.

  The hydraulic system of the work machine includes a work hydraulic actuator, a work control valve 300 that controls hydraulic oil supplied to the work hydraulic actuator, a hydraulic lock switching valve 310 that can shut off hydraulic oil supplied to the work control valve 300, Traveling pumps 52L, 52R for driving the traveling device based on the pressure of the hydraulic oil, an anti-stall proportional valve 81b capable of controlling hydraulic oil supplied to the traveling pumps 52L, 52R, a work control valve 300, and a hydraulic lock switching valve 310 , A second oil passage 62 connecting the traveling pumps 52L, 52R and the anti-stall proportional valve 81b, and a third oil passage connecting the first oil passage 361 and the second oil passage 62. An oil passage 363, and the anti-stall proportional valve 81b is set to a pressure higher than the pressure set by the hydraulic lock switching valve 310 (set pressure PV1).According to this, the hydraulic oil in the second oil passage 62 can flow through the third oil passage 363 and the first oil passage 361 by the anti-stall proportional valve 81b, so that warm-up can be performed.

[Third embodiment]
FIG. 6 shows a hydraulic system of a working machine according to the third embodiment. In the third embodiment, as shown in FIG. 6, the first hydraulic device is a work control valve 300, the first operating valve is a hydraulic lock switching valve 310, the second hydraulic device is a travel motor (HST motor) 36, The second operating valve is a shift switching valve 33. As shown in FIG. 6, for example, a throttle portion 467 is provided on the upstream side of the shift switching valve 33. The throttle 467 is provided between the connection between the third oil passage 463 and the second oil passage 462 and the transmission switching valve 33, or when the transmission switching valve 33 is in the second position 33b. It may be provided in the oil passage.

  The first oil passage connects a first hydraulic device (work control valve 300) and a first hydraulic valve (hydraulic lock switching valve 310) that controls hydraulic oil supplied to the first hydraulic device (work control valve 300). The oil passage 361 is formed. The second oil passage connects the second hydraulic device (traveling motor 36) and a second operating valve (speed changeover switching valve 33) that controls hydraulic oil supplied to the second hydraulic device (traveling motor 36). 462. The third oil passage is an oil passage 463 connecting the first oil passage 361 and the second oil passage 462. A check valve 473 is connected to the third oil passage 463. The check valve 473 allows the operating oil from the second oil passage 462 to the first oil passage 361 and blocks the operating oil from the first oil passage 361 to the second oil passage 62. Further, on both sides of the check valve 473, bypass oil passages 474 are provided. The bypass oil passage 474 is provided with a throttle portion 477 for reducing the flow rate of the working oil.

  Therefore, the control device 90 sets the shift switching valve 33 to the second position 33b at least when the traveling drive mechanism 34 is not operating (when the first operation member 54 is not operated). As a result, the hydraulic oil (pilot oil) in the second oil passage 462 passes through the third oil passage 463 and the hydraulic lock switching valve 310, and is discharged from the discharge port of the hydraulic lock switching valve 310 to the first discharge oil passage 366. can do. That is, in the third embodiment, warm-up can be performed by enabling the hydraulic lock switching valve 310 of the working machine system and the transmission switching valve 33 to communicate with each other through the third oil passage 463.

  In the case of the hydraulic lock mode, when the temperature of the pilot oil detected by the temperature detecting device 91 becomes equal to or lower than a predetermined temperature, the warm-up mode is set. In this case, the hydraulic lock switching valve 310 switches to the first position 310a, while the shift switching valve 33 switches to the second position 33b. When not in the warm-up mode, the hydraulic lock switching valve 310 is held at the first position 310a, and the shift switching valve 33 is at the first position 33a.

Also, in situations other than the setting pressure PV2> the setting pressure PV1, and when the setting pressure PV2 of the shift switching valve 33 becomes lower than the pressure (PV1) of the output port 310c of the hydraulic lock switching valve 310, the secondary pilot It is also possible to discharge the oil to the second discharge oil passage 67 through the shift switching valve 33.
For example, in the case of the parking mode, the hydraulic lock switching valve 310 is held at the second position 310b, and the shift switching valve 33 is at the first position 33a. As a result, the pilot oil in the first oil passage 361 is discharged through the bypass oil passage 474 and the transmission switching valve 33.

  In the operation mode, when the temperature of the pilot oil detected by the temperature detection device 91 becomes equal to or lower than a predetermined temperature, the mode is set to the warm-up mode. In the warm-up mode, even when the driver (operator) performs an operation of switching the operation member 58 to the second speed, the shift member 33 is not switched by the operation member 58, and the shift valve 33 is held at the first position 33a. Is done. Further, the hydraulic lock switching valve 310 is held at the second position 310b. As a result, the pilot oil in the first oil passage 361 is discharged through the bypass oil passage 474 and the transmission switching valve 33.

  The hydraulic system of the work machine includes a work hydraulic actuator, a work control valve 300 that controls hydraulic oil supplied to the work hydraulic actuator, a hydraulic lock switching valve 310 that can shut off hydraulic oil supplied to the work control valve 300, A traveling motor 36 capable of shifting the traveling device based on the pressure of the hydraulic oil, a shift switching valve 33 capable of controlling hydraulic oil supplied to the traveling motor 36 and performing a shift, a work control valve 300 and a hydraulic lock switching valve 310, a second oil passage 462 connecting the traveling motor 36 and the shift switching valve 33, and a third oil passage connecting the first oil passage 361 and the second oil passage 462. 463, and the shift switching valve 33 is set to a pressure higher than the pressure (set pressure PV1) set by the hydraulic lock switching valve 310. According to this, the warm-up can be performed by flowing the hydraulic oil in the second oil passage 462 through the third oil passage 463 and the first oil passage 361 by the shift switching valve 33.

[Fourth embodiment]
FIG. 7 shows a hydraulic system of a working machine according to a fourth embodiment. In the fourth embodiment, as shown in FIG. 7, the first hydraulic device is the brake mechanism 30, the first operating valve is the brake switching valve 80a, and the second hydraulic device is the travel pumps 52L and 52R of the travel drive mechanism 34. The second operating valve is a plurality of operating valves 55 (55a, 55b, 55c, 55d). The plurality of operation valves 55 (55a, 55b, 55c, and 55d) serving as the second operation valves are traveling operation valves that control hydraulic oil supplied to the traveling pumps 52L and 52R.

  The first oil passage is an oil passage 61 that connects the first hydraulic device (brake mechanism 30) and a first operating valve (brake switching valve) that controls hydraulic oil supplied to the first hydraulic device (brake mechanism 30). It is. The second oil passage controls a second hydraulic device (the traveling pumps 52L and 52R of the traveling drive mechanism 34) and a second hydraulic device that controls hydraulic oil supplied to the second hydraulic devices (the traveling pumps 52L and 52R of the traveling drive mechanism 34). Traveling oil passages 45 (first traveling oil passage 45a, second traveling oil passage 45b, third traveling oil passage 45c, and fourth traveling oil passage 45d) that connect to operation valves (operation valves 55a, 55b, 55c, and 55d). It is. The third oil passage is an oil passage 563 that connects the first oil passage 61 and the second oil passage 45. A check valve 573 is connected to the third oil passage 563. The check valve 573 allows the operating oil from the second oil passage 45 to the first oil passage 61 and blocks the operating oil from the first oil passage 61 to the second oil passage 45.

  The operation valves 55 a, 55 b, 55 c, and 55 d are proportional solenoid valves, and the degree of opening can be changed according to a control signal from the control device 90. A swingable operation member 96 is connected to the control device 90. When the operation member 96 is operated in a direction corresponding to the forward movement, the operation valves 55a and 55c open according to the operation amount of the operation member 96, and the traveling pumps 52L and 52R rotate forward. When the operation member 96 is operated in the direction corresponding to the reverse, the operation valves 55b and 55d are opened according to the operation amount of the operation member 96, and the traveling pumps 52L and 52R rotate in the reverse direction. When the operation member 96 is operated in the direction corresponding to the left turn, the operation valves 55b and 55c open according to the operation amount of the operation member 96, and the traveling pump 52L rotates in the reverse direction and the traveling pump 52R rotates in the forward direction. When the operation member 96 is operated in the direction corresponding to the right turn, the operation valves 55a and 55d are opened according to the operation amount of the operation member 96, and the traveling pump 52L rotates forward and the traveling pump 52R rotates reversely. As described above, the operation of the operation member 96 allows the operation valves 55a, 55b, 55c, and 55d to be operated.

  For example, in the warm-up mode, the control device 90 changes the set pressure (PV2) of the operation valves 55a, 55b, 55c, and 55d regardless of the operation of the operation member 96, and sets the brake set pressure PV1 of the brake switching valve 80a. Higher than More specifically, in the warm-up mode, the controller 90 sets the brake switching valve 80a to the first position 80a1 while increasing the opening degrees of the operation valves 55a, 55b, 55c, and 55d, thereby controlling the operation valve 55a. , 55b, 55c, and 55d are set to be larger than the brake set pressure PV1. That is, when the brake switching valve 80a is in the braking state, the operating oil (pilot oil) of the traveling oil passage 45 is increased by increasing the operation valves 55a, 55b, 55c, and 55d, so that the check valve 573 and the third valve 573 By flowing the oil to the first discharge oil passage 66 through the oil passage 563, the first oil passage 61, and the brake switching valve 80a, warm-up can be performed.

The set pressures (PV2) of the operation valves 55a, 55b, 55c, and 55d may be the same pressure or different pressures. Further, the set pressure (PV2) of the operation valves 55a, 55b, 55c, and 55d may be sequentially set to be higher than the brake set pressure PV1.
The hydraulic system of the work machine includes a brake mechanism 30, a brake actuation valve 80a, traveling pumps 52L, 52R, operation valves 55a, 55b, 55c, 55d, and a first mechanism for connecting the brake mechanism 30 and the brake actuation valve 80a. An oil passage 61, a second oil passage 45 connecting the traveling pumps 52L, 52R and the operation valves 55a, 55b, 55c, 55d, and a third oil passage connecting the first oil passage 61 and the second oil passage 45. 563. According to this, the operating oil in the second oil passage 45 can flow to the brake operating valve 80a through the third oil passage 563 and the first oil passage 61 by the operation valves 55a, 55b, 55c, and 55d, Warm up can be performed.

[Fifth Embodiment]
FIG. 8 shows a hydraulic system of a working machine according to a fifth embodiment. The hydraulic system shown in FIG. 8 is a traveling hydraulic system and includes traveling pumps 52L and 52R and operation valves 155L and 155R.
Each of the traveling pumps 52L, 52R includes a regulator 156L, 156R. The regulators 156L and 156R can change the angle of the swash plate (swash plate angle) of the traveling pumps 52L and 52R, supply a working oil to the supply chamber 157, and a piston rod 158 provided in the supply chamber 157. Contains. The piston rod 158 is connected to the swash plate, and the angle of the swash plate can be changed by the operation of the piston rod 158.

  The operation valve 155L is a valve that operates the regulator 156L, that is, a valve that controls hydraulic oil supplied to the traveling pump 52L. The operation valve 155L is an electromagnetic valve, and the spool moves based on a control signal given to the solenoid 160L from the control device 90, and the opening degree due to the movement of the spool changes. Further, the operation valve 155L can be switched between a first position 159a, a second position 159b, and a neutral position 159c.

The first port of the operation valve 155L and the supply chamber 157 of the regulator 156L are connected by a first traveling oil passage 145a. The second port of the operation valve 155L and the supply chamber 157 of the regulator 156L are connected by a second traveling oil passage 145b.
The operation valve 155R is a valve that operates the regulator 156R, that is, a valve that controls hydraulic oil supplied to the traveling pump 52R. The operation valve 155R is an electromagnetic valve, and the spool moves based on a control signal given from the control device 90 to the solenoid 160R, and the opening degree due to the movement of the spool changes. Further, the operation valve 155R can be switched between a first position 159a, a second position 159b, and a neutral position 159c.

The first port of the operation valve 155R and the supply chamber 157 of the regulator 156L are connected by a third traveling oil passage 145c. The second port of the operation valve 155L and the supply chamber 157 of the regulator 156L are connected by a fourth traveling oil passage 145d.
When the operation valves 155L and 155R are switched to the first position 159a, the traveling pumps 52L and 52R rotate forward, and when the operation valves 155L and 155R are switched to the second position 159b, the traveling pumps 52L and 52R become Reverse. When the operation valve 155L is switched to the first position 159a and the operation valve 155R is switched to the second position 159b, the traveling pump 52L rotates forward and the traveling pump 52R reverses. When the operation valve 155L is switched to the second position 159b and the operation valve 155R is switched to the first position 159a, the traveling pump 52L rotates in the reverse direction and the traveling pump 52R rotates in the forward direction. Therefore, the operation valve 155L and the operation valve 155R can switch the traveling pumps 52L and 52R between forward rotation and reverse rotation, and are one of traveling operation valves.

Now, in the hydraulic system for a working machine according to the fifth embodiment, warm-up can be performed by switching between the brake switching valve 80a and the operation valves 155L and 155R.
As shown in FIG. 8, the first hydraulic device is the brake mechanism 30, the first operating valve is a brake switching valve 80a, the second hydraulic device is the traveling pumps 52L and 52R, the second operating valve is an operation valve 155L, This is the operation valve 155R.

  The first oil passage is an oil passage 61 that connects the first hydraulic device (brake mechanism 30) and a first operating valve (brake switching valve) that controls hydraulic oil supplied to the first hydraulic device (brake mechanism 30). It is. The second oil passage controls a second hydraulic device (the traveling pumps 52L and 52R of the traveling drive mechanism 34) and a second hydraulic device that controls hydraulic oil supplied to the second hydraulic devices (the traveling pumps 52L and 52R of the traveling drive mechanism 34). These are traveling oil passages (first traveling oil passage 145a, second traveling oil passage 145b, third traveling oil passage 145c, and fourth traveling oil passage 145d) that connect to operation valves (operating valves 155L and 155R).

  The third oil passage connects the first oil passage 61 and the second oil passage (first traveling oil passage 145a, second traveling oil passage 145b, third traveling oil passage 145c, and fourth traveling oil passage 145d). Road 663. The third oil passage 663 includes an oil passage 663a connected to the first travel oil passage 145a, an oil passage 663b connected to the second travel oil passage 145b, an oil passage 663c connected to the third travel oil passage 145c, It includes an oil passage 663d connected to the four traveling oil passage 145d. The third oil passage 663 includes an oil passage 663e that joins the oil passages 663a, 663b, 663c, and 663d.

  A high-pressure selection valve 610L is connected to a junction where the oil passages 663a and 663b merge, and a high-pressure selection valve 610R is also connected to a junction where the oil passages 663c and 663d merge. One end of the oil passage 663e is connected to the high-pressure selection valves 610L and 610R, and the other end is connected to the first oil passage 61. In the oil passage 663e, a check valve 611 is connected to the first oil passage 61 closer to the first oil passage 61 than the high-pressure selection valves 610L and 610R. The check valve 611 allows hydraulic oil from the high-pressure selection valves 610L and 610R to the first oil passage 61 and blocks hydraulic oil from the first oil passage 61 to the high-pressure selection valves 610L and 610R.

  For example, in the warm-up mode, the control device 90 sets the set pressure (PV2) of the operation valve 155L and the operation valve 155R higher than the brake set pressure PV1 of the brake switching valve 80a. More specifically, in the warm-up mode, the control device 90 switches the operation valve 155L and the operation valve 155R to the first position 159a while setting the brake switching valve 80a to the first position 80a1 to thereby control the operation valves 155L and 155R. The set pressure (PV2) of the operation valve 155R is set higher than the brake set pressure PV1. That is, when the brake switching valve 80a is in the braking state, the operating oil (pilot oil) of the traveling oil passage 145 is increased by increasing the opening of the operating valve 155L and the operating valve 155R, and the high-pressure selection valves 610L and 610R. By flowing the fluid through the first oil passage 663, the third oil passage 663, the first oil passage 61, and the brake switching valve 80a, the warm-up can be performed. Note that, in the warm-up mode, the control device 90 does not limit the switching of the operation valves 155L and 155R to the above-described example, and may switch the operation valves 155L and 155R to the second position 159b. Alternatively, one of the operation valve 155L and the operation valve 155R may be switched to the first position 159a, and the other may be switched to the second position 159b.

FIG. 9 shows a modification of the hydraulic system of the working machine according to the fifth embodiment. In FIG. 9, the description of the same configuration as that of the fifth embodiment is omitted.
As shown in FIG. 9, the third oil passage 663 is connected to an oil passage 663a connected to the first traveling oil passage 145a, an oil passage 663b connected to the second traveling oil passage 145b, and a third traveling oil passage 145c. Oil path 663c, and an oil path 663d connected to the fourth traveling oil path 145d. The third oil passage 663 includes an oil passage 663e that joins the oil passages 663a, 663b, 663c, and 663d. A check valve 612 is connected to each of the oil passages 663a, 663b, 663c, and 663d. The check valve 612 allows hydraulic oil from the second oil passage to the first oil passage 61 and blocks hydraulic oil from the first oil passage 61 to the second oil passage. Also in the modification example of FIG. 9, in the warm-up mode, the control device 90 switches the operation valve 155 </ b> L and the operation valve 155 </ b> R to transfer the hydraulic oil in the second oil passage through the third oil passage 663 to the first oil passage. By flowing the oil through the oil passage 61, warm-up can be performed.

The first traveling oil passage 145a, the second traveling oil passage 145b, the third traveling oil passage 145c, and the fourth traveling oil passage 145d are provided with a throttle 166 for reducing the flow rate of the working oil. Since the flow rate supplied / discharged to the supply chamber 157 is reduced by the throttle 166, the traveling performance (operability) can be improved so as not to be suddenly accelerated or decelerated.
When warming up, switching between the first position 159a and the second position 159b of the operation valve 155L and the operation valve 155R may be performed alternately. The pilot oil acting on the traveling oil passages (the first traveling oil passage 145a, the second traveling oil passage 145b, the third traveling oil passage 145c, and the fourth traveling oil passage 145d) is supplied to the brake operating valve 80a via the oil passage 663e. Since the swash plates of the HST pumps (travel pumps) 52L and 52R are held at the neutral position without tilting because they are discharged from the first discharge oil passage 66.

  Although the present invention has been described above, it should be understood that the embodiments disclosed herein are illustrative in all aspects 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.

REFERENCE SIGNS LIST 1 work machine 7 traveling device 30 brake mechanism 61 first oil passage 62 second oil passage 63 third oil passage 66 first discharge oil passage 67 second discharge oil passage 68 first bypass oil passage 71 first check valve 80a brake Operating valve 81a Transmission operating valve 81b: Anti-stall proportional valve 300: Work control valve (boom control valve)
300a: pressure receiving portion 300b: pressure receiving portion 310: hydraulic lock switching valve 310a: first position 310b: second position 310c: output port 310d: discharge port 320: working oil passage 330: operating valve 330a: operating valve 330b: operating valve 331 : Operation member 361: first oil passage 363: third oil passage 373: check valve 374: bypass oil passage 462: second oil passage 463: third oil passage 473: check valve 474: bypass oil passage 563: first 3 oil passage 573: check valve 610L: high pressure selection valve 610R: high pressure selection valve 611: check valve 612: check valve 663: third oil passage 663a: oil passage 663b: oil passage 663c: oil passage 663d: oil passage 663e: oil passage P1: first hydraulic pump PV2: set pressure P1 hydraulic pump

Claims (8)

A hydraulic pump that discharges hydraulic oil,
A brake mechanism that performs braking of the traveling device and release of the braking based on the pressure of the hydraulic oil,
A traveling pump that drives the traveling device based on the pressure of the hydraulic oil,
A brake actuation valve for controlling the hydraulic oil supplied to the brake mechanism;
A travel operating valve for controlling hydraulic oil supplied to the travel pump,
A first oil passage connecting the brake mechanism and the brake actuation valve;
A second oil passage connecting the traveling pump and the traveling operation valve;
A third oil passage connecting the first oil passage and the second oil passage,
A first discharge oil passage communicating with the brake operation valve and discharging hydraulic oil passing through the brake operation valve;
A second discharge oil passage communicating with the travel operation valve and discharging hydraulic oil that has passed through the travel operation valve;
With
The hydraulic system for a working machine, wherein the travel operating valve is set to a pressure higher than a brake set pressure set by the brake operating valve.   The work according to claim 1, wherein the brake actuating valve is a brake switching valve that can be switched between a first position where the brake mechanism sets a braking pressure at which the braking is performed and a second position where the brake mechanism sets the release pressure. Machine hydraulic system.   The hydraulic system for a working machine according to claim 1, wherein the brake actuating valve is a brake proportional valve that is variable from a braking pressure at which the brake mechanism performs the braking to the release pressure. The second oil passage is provided with an operation valve capable of changing a pressure for supplying hydraulic oil to the traveling pump in accordance with an operation,
The hydraulic system for a working machine according to claim 1, wherein the third oil passage is connected to a section between the traveling operation valve and the operation valve in the second oil passage. The second oil passage is provided with an operation valve capable of changing a pressure for supplying hydraulic oil to the traveling pump in accordance with an operation,
The third oil passage is connected to the section between the operation valve and the traveling pump in the second oil passage,
The hydraulic system for a working machine according to any one of claims 1 to 3, wherein the traveling operation valve is provided on the second oil passage at an upstream side of the operation valve.   The travel operating valve is an anti-stall proportional valve that changes the pressure of hydraulic oil to the hydraulic pump based on the rotation speed of a prime mover, or a hydraulic lock switching valve that can stop supply of hydraulic oil to the operating valve. The hydraulic system for a working machine according to claim 4 or 5.   A check valve that is provided in the third oil passage and that allows hydraulic oil from the second oil passage to the first oil passage and that blocks hydraulic oil from the first oil passage to the second oil passage; The hydraulic system for a working machine according to any one of claims 1 to 6, further comprising: A traveling motor operable by hydraulic oil discharged from the traveling pump,
A shift oil passage connecting the traveling motor and the traveling pump;
With
The traveling pump includes a regulator that can operate a swash plate of the traveling pump,
The hydraulic system according to any one of claims 1 to 7, wherein the traveling operation valve switches the traveling pump to one of forward rotation and reverse rotation by operating the swash plate by the regulator.

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