Work Machine

Abstract

To enable the operability of travelling operation to be improved.SOLUTION: A work machine includes a first travelling oil path connected to a first pressure receiving part for operating oil working on the first pressure receiving part when operating a travelling operation member to pass therethrough, a second travelling oil path connected to a second pressure receiving part for operating oil working on the second pressure receiving part when operating a travelling operation member to pass therethrough, a third travelling oil path connected to a third pressure receiving part for operating oil working on the third pressure receiving part when operating the travelling operation member to pass therethrough, a fourth travelling oil path connected to a fourth pressure receiving part for operating oil working on the fourth pressure receiving part when operating the travelling operation member to pass therethrough, and a connection oil path connecting at least two travelling oil paths out of the first travelling oil path, the second travelling oil path, the third travelling oil path, and the fourth travelling oil path.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a work machine such as a skid steer loader, a compact track loader, a backhoe, or the like. [Background technology]

[0002] A conventional work machine is shown in Patent Document 1. The work machine of Patent Document 1 includes a travel operation device, an HST pump, and a travel oil passage that connects the travel operation device and the HST pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-8171 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the work machine of Patent Document 1, the pilot pressure of the pilot oil in the travel oil passage is changed by operating the travel operation device, and travel operations such as straight ahead, super-pivot turning, and pivot turning can be performed. In Patent Document 1, a high-pressure selection valve is provided in the travel oil passage, so travel operations can be performed smoothly, but there is a demand for smoother travel. The present invention has been made to solve the problems of the prior art as described above, and has an object to provide a working machine that can improve the operability of traveling operation. [Means for solving the problem]

[0005] The technical means adopted by the present invention to solve the technical problems are as follows. The work machine includes a body, a left traveling device provided on the left side of the body, a right traveling device provided on the right side of the body, a left traveling motor capable of transmitting power to the left traveling device, and a right traveling motor capable of transmitting power to the right traveling device, a left traveling pump having a first pressure receiving part and a second pressure receiving part, and rotating the left traveling motor in a forward direction when hydraulic oil acts on the first pressure receiving part, and rotating the left traveling motor in a reverse direction when hydraulic oil acts on the second pressure receiving part, a right traveling pump having a third pressure receiving part and a fourth pressure receiving part, and rotating the right traveling motor in a forward direction when hydraulic oil acts on the third pressure receiving part, and rotating the right traveling motor in a reverse direction when hydraulic oil acts on the fourth pressure receiving part, a traveling operation device that applies hydraulic oil to at least one of the first pressure receiving part, the second pressure receiving part, the third pressure receiving part, and the fourth pressure receiving part when a traveling operation member is operated, and is connected to the first pressure receiving part. a first travel oil passage connected to the second pressure receiving part and passing hydraulic oil acting on the second pressure receiving part when the travel operating member is operated; a second travel oil passage connected to the second pressure receiving part and passing hydraulic oil acting on the second pressure receiving part when the travel operating member is operated; a third travel oil passage connected to the third pressure receiving part and passing hydraulic oil acting on the third pressure receiving part when the travel operating member is operated; a fourth travel oil passage connected to the fourth pressure receiving part and passing hydraulic oil acting on the fourth pressure receiving part when the travel operating member is operated; a connecting oil passage connecting at least two travel oil passages among the first travel oil passage, the second travel oil passage, the third travel oil passage, and the fourth travel oil passage; and a throttle portion provided in the connecting oil passage, wherein the connecting oil passage comprises a first connecting passage connecting the first travel oil passage and the fourth travel oil passage, and a second connecting passage connecting the second travel oil passage and the third travel oil passage. and The throttle portion is provided in both the first connecting path and the second connecting path.

[0006] Made by The industrial machine includes an actuated valve capable of changing the pressure of hydraulic oil supplied to the traveling operation device, and a first oil passage connecting the traveling operation device and the actuated valve.

[0007] The work machine includes a second oil passage that connects the first oil passage to the first and third travel oil passages. 。 Effect of the Invention

[0008] According to the present invention, the operability of driving operations can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram showing a hydraulic system (hydraulic circuit) of a traveling-type working machine in the first embodiment. [Diagram 2] FIG. 2 is a diagram showing a hydraulic system (hydraulic circuit) of a work machine of a work system in the first embodiment. [Diagram 3] FIG. 11 is a diagram showing a hydraulic system (hydraulic circuit) of a traveling-type work machine in the second embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the primary travel pressure (control signal) and the rotation speed of the prime mover. [Figure 5A] FIG. 13 is a diagram showing a modified example of a connecting oil passage. [Figure 5B] 5B is a diagram showing a modified example of a connecting oil passage different from that shown in FIG. 5A. [Figure 6] FIG. 11 is a diagram showing a hydraulic system (hydraulic circuit) of a work machine of a work system in a third embodiment. [Figure 7A] FIG. 13 is a diagram showing an example in which a communicating oil passage is provided in a spool. [Figure 7B] 13 is a diagram showing an example in which a communicating oil passage is provided in a location different from a spool.FIG. 14 is a diagram showing a modified example of a hydraulic system (hydraulic circuit) of a work machine.FIG. [Figure 8] FIG. 1 is a side view showing a track loader as an example of a work machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a hydraulic system for a work machine and a work machine equipped with this hydraulic system according to the present invention will be described with reference to the drawings as appropriate. [First embodiment] Fig. 8 shows a side view of a working machine according to the present invention. Fig. 8 shows a compact track loader as an example of a working machine. However, the working machine according to the present invention is not limited to a compact track loader, and may be, for example, another type of loader working machine, such as a skid steer loader. Also, the working machine may be a working machine other than a loader working machine.

[0011] As shown in FIG. 8, 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. 8) of the driver seated in the driver's seat 8 of the working machine 1 will be described as the front, the rear side of the driver (right side in FIG. 8) as the rear, the left side of the driver (near side in FIG. 8) as the left side, and the right side of the driver (far side in FIG. 8) as the right side. In addition, the horizontal direction perpendicular to the front-rear direction will be described as the machine body width direction. The direction from the center of the machine body 2 to the right or left side will be described as the machine body outside. In other words, the machine body outside is the machine body width direction, and is the direction away from the machine body 2. The opposite direction to the machine body outside will be described as the machine body inside. In other words, the machine body inside is the machine body width direction, and is the direction approaching the machine body 2.

[0012] The cabin 3 is mounted on the machine body 2. A driver's seat 8 is provided in the cabin 3. The working device 4 is attached to the machine body 2. The traveling device 5 is provided on the outside of the machine body 2. A prime mover 32 is mounted at the rear inside the machine body 2. The work device 4 has a boom 10, a work implement 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

[0013] The boom 10 is provided on the right and left sides of the cabin 3 so as to be able to swing up and down. The work implement 11 is, for example, a bucket, and the bucket 11 is provided on the tip (front end) of the boom 10 so as to be able to swing up and down. A lift link 12 and a control link 13 support the base (rear) of the boom 10 so that the boom 10 can swing up and down. A boom cylinder 14 raises and lowers the boom 10 by extending and retracting. A bucket cylinder 15 swings the bucket 11 by extending and retracting.

[0014] The front portions of the left and right booms 10 are connected to each other by a connecting pipe having an irregular shape, and the base portions (rear portions) of the booms 10 are connected to each other by a circular connecting pipe. The lift link 12, the control link 13 and the boom cylinder 14 are provided on the left and right sides of the machine body 2 corresponding to the left and right booms 10, respectively. The lift link 12 is provided vertically at the rear of the base of each boom 10. An upper portion (one end side) of this lift link 12 is pivoted rotatably about a horizontal axis via a pivot shaft 16 (first pivot shaft) near the rear of the base of each boom 10. A lower portion (the other end side) of the lift link 12 is pivoted rotatably about a horizontal axis via a pivot shaft 17 (second pivot shaft) near the rear of the aircraft body 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

[0015] An upper portion of the boom cylinder 14 is pivoted rotatably about a horizontal axis via a pivot shaft 18 (third pivot shaft). The third pivot shaft 18 is the base of each boom 10 and is provided at the front of the base. A lower portion of the boom cylinder 14 is pivoted rotatably about a horizontal axis via a pivot shaft 19 (fourth pivot shaft). The fourth pivot shaft 19 is provided below the third pivot shaft 18, toward the lower rear portion of the machine body 2.

[0016] The control link 13 is provided in front of the lift link 12. One end of the control link 13 is pivoted to be rotatable about a horizontal axis via a pivot shaft 20 (fifth pivot shaft). The fifth pivot shaft 20 is provided on the aircraft body 2 at a position corresponding to the front of the lift link 12. The other end of the control link 13 is pivoted to be rotatable about a horizontal axis via a pivot shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is provided on the boom 10 in front of and above the second pivot shaft 17.

[0017] By extending and retracting the boom cylinder 14, the base of each boom 10 is supported by the lift link 12 and the control link 13, while each boom 10 swings up and down about the first pivot shaft 16, and the tip of each boom 10 rises and falls. The control link 13 swings up and down about the fifth pivot shaft 20 in conjunction with the up and down swing of each boom 10. The lift link 12 swings back and forth about the second pivot shaft 17 in conjunction with the up and down swing of the control link 13.

[0018] Instead of the bucket 11, another working tool can be attached to the front of the boom 10. The other working tool can be, for example, an attachment (spare attachment) such as a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower. A connection member 50 is provided at the front of the left boom 10. The connection member 50 is a device that connects hydraulic equipment provided on the spare attachment to a first tubular member such as a pipe provided on the boom 10. Specifically, the first tubular member can be connected to one end of the connection member 50, and the second tubular member connected to the hydraulic equipment of the spare attachment can be connected to the other end. This allows the hydraulic oil flowing through the first tubular member to pass through the second tubular member and be supplied to the hydraulic equipment.

[0019] The bucket cylinders 15 are disposed near the front of each boom 10. By extending and contracting the bucket cylinders 15, the bucket 11 is swung. In this embodiment, crawler type (including semi-crawler type) traveling devices are used as the left and right traveling devices (first traveling device, second traveling device) 5. Note that wheel-type traveling devices having front and rear wheels may also be used.

[0020] The prime mover 32 is an internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, etc. In this embodiment, the prime mover 32 is a diesel engine, but is not limited to this. Next, the hydraulic system of the traveling system of the work machine will be described. As shown in FIG. 1, the hydraulic system of the work machine includes a first hydraulic pump P1 and a second hydraulic pump P2. The first hydraulic pump P1 is a pump driven by the power of a prime mover 32, and is configured by a fixed displacement gear pump. The first hydraulic pump P1 is capable of discharging hydraulic oil stored in a tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 that stores the hydraulic oil may be referred to as a hydraulic oil tank. In addition, the hydraulic oil used for control among the hydraulic oil discharged from the first hydraulic pump P1 may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

[0021] The second hydraulic pump P2 is a pump driven by the power of the prime mover 32, and is configured by a fixed displacement gear pump. The second hydraulic pump P2 is capable of discharging hydraulic oil stored in the tank 22, and supplies hydraulic oil to, for example, an oil passage of a work system. For example, the second hydraulic pump P2 supplies hydraulic oil to a boom cylinder 14 that operates the boom 10, a bucket cylinder 15 that operates the bucket, and a control valve (flow control valve) that controls a standby hydraulic actuator that operates a standby hydraulic actuator.

[0022] The hydraulic system of the work machine also includes a pair of travel motors 36L, 36R and a pair of travel pumps 53L, 53R. The pair of travel motors 36L, 36R are motors that transmit power to the pair of travel devices 5L, 5R. Of the pair of travel motors 36L, 36R, one travel motor 36L transmits rotational power to the travel device (left travel device) 5L, and the other travel motor 36R transmits rotational power to the travel device (right travel device) 5R.

[0023] The pair of travel pumps 53L, 53R are pumps driven by the power of the prime mover 32, and are, for example, swash plate type variable displacement axial pumps. When driven, the pair of travel pumps 53L, 53R supply hydraulic oil to each of the pair of travel motors 36L, 36R. Of the pair of travel pumps 53L, 53R, one travel pump 53L supplies hydraulic oil to the travel pump 53L, and the other travel pump 53R supplies hydraulic oil to the travel pump 53R.

[0024] Hereinafter, for ease of explanation, the travel pump 53L may be referred to as the left travel pump 53L, the travel pump 53R as the right travel pump 53R, the travel motor 36L as the left travel motor 36L, and the travel motor 36R as the right travel motor 36R. Left travel pump 53L and right travel pump 53 R is The first hydraulic pump P1 has a pressure receiving portion 53a and a pressure receiving portion 53b on which the pressure (pilot pressure) of the hydraulic oil (pilot oil) from the first hydraulic pump P1 acts. 。 The angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 53a and 53b. board By changing the angle, it is possible to change the output (discharge amount of hydraulic oil) of the left traveling pump 53L and the right traveling pump 53R and the discharge direction of the hydraulic oil.

[0025] The left traveling pump 53L and the left traveling motor 36L are connected by a connecting oil passage 57h, and hydraulic oil discharged by the left traveling pump 53L is supplied to the left traveling motor 36L. The right traveling pump 53R and the right traveling motor 36R are connected by a connecting oil passage 57i, and hydraulic oil discharged by the right traveling pump 53R is supplied to the right traveling motor 36R. The left traveling motor 36L can be rotated by hydraulic oil discharged from the left traveling pump 53L, and the rotation speed (number of rotations) can be changed by the flow rate of the hydraulic oil. A swash plate switching cylinder 37L is connected to the left traveling motor 36L, and the rotation speed (number of rotations) of the left traveling motor 36L can also be changed by expanding or contracting the swash plate switching cylinder 37L to one side or the other side. That is, when the swash plate switching cylinder 37L is contracted, the rotation speed of the left traveling motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is expanded, the rotation speed of the left traveling motor 36L is set to a high speed (second speed). That is, the rotation speed of the left traveling motor 36L can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

[0026] The right traveling motor 36R can be rotated by hydraulic oil discharged from the right traveling pump 53R, and the rotation speed (number of rotations) can be changed by the flow rate of the hydraulic oil. A swash plate switching cylinder 37R is connected to the right traveling motor 36R, and the rotation speed (number of rotations) of the right traveling motor 36R can also be changed by expanding or contracting the swash plate switching cylinder 37R to one side or the other side. That is, when the swash plate switching cylinder 37R is contracted, the rotation speed of the right traveling motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is expanded, the rotation speed of the right traveling motor 36R is set to a high speed (second speed). That is, the rotation speed of the right traveling motor 36R can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

[0027] 1, the hydraulic system of the work machine includes a travel switching valve 34. The travel switching valve 34 is switchable between a first state in which the rotation speed (revolutions) of the travel motors (left travel motor 36L, right travel motor 36R) is set to a first speed, and a second state in which the rotation speed (revolutions) is set to a second speed. The travel switching valve 34 includes first switching valves 71L, 71R and a second switching valve 72. The first switching valve 71L is connected to the swash plate switching cylinder 37L of the left traveling motor 36L via an oil passage and is a two-position switching valve that can be switched between a first position 71L1 and a second position 71L2. When the first switching valve 71L is in the first position 71L1, the swash plate switching cylinder 37L is contracted, and when the first switching valve 71L is in the second position 71L2, the swash plate switching cylinder 37L is extended.

[0028] The first switching valve 71R is connected to the swash plate switching cylinder 37R of the right traveling motor 36R via an oil passage and is a two-position switching valve that can be switched between a first position 71R1 and a second position 71R2. When the first switching valve 71R is in the first position 71R1, the swash plate switching cylinder 37R is contracted, and when the first switching valve 71R is in the second position 71R2, the swash plate switching cylinder 37R is extended. The second switching valve 72 is a solenoid valve that switches the first switching valve 71L and the first switching valve 71R, and is a two-position switching valve that can be switched between a first position 72a and a second position 72b by excitation. The second switching valve 72, the first switching valve 71L, and the first switching valve 71R are connected by an oil passage 41. When the second switching valve 72 is in the first position 72a, the second switching valve 72 switches the first switching valve 71L and the first switching valve 71R to the first positions 71L1 and 71R1, and when the second position 72b, the first switching valve 71L and the first switching valve 71R to the second positions 71L2 and 71R2.

[0029] In other words, when the second switching valve 72 is in the first position 72a, the first switching valve 71L is in the first position 71L1, and the first switching valve 71R is in the first position 71R1, the travel switching valve 34 is in the first state, and the rotation speed of the travel motors (left travel motor 36L, right travel motor 36R) is set to the first speed. When the second switching valve 72 is in the second position 72b, the first switching valve 71L is in the second position 71L2, and the first switching valve 71R is in the second position 71R2, the travel switching valve 34 is in the second state, and the rotation speed of the travel motors (left travel motor 36L, right travel motor 36R) is set to the second speed.

[0030] Therefore, the travel switching valve 34 can switch the travel motors (left travel motor 36L, right travel motor 36R) between a first speed, which is a low speed side, and a second speed, which is a high speed side. The operation device (travel operation device) 54 is a device that applies hydraulic oil to the pressure receiving parts 53a, 53b of the travel pumps (left travel pump 53L, right travel pump 53R) when the travel operation member 59 is operated, and can change the angle of the swash plate (swash plate angle) of the travel pump. The operation device 54 includes the travel operation member 59 and a plurality of operation valves 55.

[0031] The travel operation member 59 is an operation lever supported by the operation valve 55 and swung left and right (machine width direction) or front and rear. That is, the travel operation member 59 can be operated to the right and left from the neutral position N as well as forward and backward from the neutral position N, with the neutral position N being taken as a reference. In other words, the travel operation member 59 can be swung in at least four directions with the neutral position N as a reference. For ease of explanation, both forward and backward directions, i.e., the front and rear directions, are referred to as the first direction. Also, both right and left directions, i.e., the left and right directions (machine width direction), are sometimes referred to as the second direction.

[0032] Further, the multiple operation valves 55 are commonly operated, that is, by one travel operation member 59. The multiple operation valves 55 operate based on the swinging of the travel operation member 59. A discharge oil passage 40 is connected to the multiple operation valves 55, and hydraulic oil (pilot oil) can be supplied from the first hydraulic pump P1 via the discharge oil passage 40. The multiple operation valves 55 are operation valve 55A, operation valve 55B, operation valve 55C, and operation valve 55D.

[0033] When the travel operating member 59 is swung forward (one side) in the front-rear direction (first direction) (when operated forward), the pressure of the hydraulic oil output by the operating valve 55A changes according to the operation amount (operation) of the forward operation. When the travel operating member 59 is swung backward (the other side) in the front-rear direction (first direction) (when operated backward), the pressure of the hydraulic oil output by the operating valve 55B changes according to the operation amount (operation) of the backward operation. When the travel operating member 59 is swung right (one side) in the left-right direction (second direction), the pressure of the hydraulic oil output by the operating valve 55C changes according to the operation amount (operation) of the right operation. When the travel operating member 59 is swung left (the other side) in the left-right direction (second direction), the pressure of the hydraulic oil output by the operating valve 55D changes according to the operation amount (operation) of the left operation.

[0034] The multiple operating valves 55 and the travel pumps (left travel pump 53L, right travel pump 53R) are connected by the travel oil passage 45. In other words, the travel pumps (left travel pump 53L, right travel pump 53R) are hydraulic devices that can be operated by hydraulic oil output from the operating valves 55 (operation valve 55A, operation valve 55B, operation valve 55C, operation valve 55D). The travel oil passage 45 has a first travel oil passage 45a, a second travel oil passage 45b, a third travel oil passage 45c, a fourth travel oil passage 45d, and a fifth travel oil passage 45e. The first travel oil passage 45a is an oil passage connected to the pressure receiving part (first pressure receiving part) 53a of the left travel pump 53L, and is an oil passage through which the hydraulic oil acting on the pressure receiving part (first pressure receiving part) 53a when the travel operation member 59 is operated passes. The second travel oil passage 45b is an oil passage connected to the pressure receiving part (second pressure receiving part) 53b of the left travel pump 53L, and is an oil passage through which the hydraulic oil acting on the pressure receiving part (second pressure receiving part) 53b passes when the travel operation member 59 is operated. The third travel oil passage 45c is an oil passage connected to the pressure receiving portion (third pressure receiving portion) 53a of the right travel pump 53R, and is an oil passage through which hydraulic oil acting on the pressure receiving portion (third pressure receiving portion) 53a passes when the travel operation member 59 is operated. The fourth travel oil passage 45d is an oil passage connected to the pressure receiving portion (fourth pressure receiving portion) 53b of the right travel pump 53R, and is an oil passage through which hydraulic oil acting on the pressure receiving portion (fourth pressure receiving portion) 53b passes when the travel operation member 59 is operated. The fifth travel oil passage 45e is an oil passage that connects the operation valve 55, the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d. A plurality of high pressure selection valves 47a, 47b, 47c, and 47d are provided in the fifth travel oil passage 45e. A plurality of high pressure selection valves 47a, 47b, 47c, 47d are connected to the first running oil passage 45a, the second running oil passage 45b, the third running oil passage 45c, and the fourth running oil passage 45d, and flow the hydraulic oil to the one having the higher hydraulic oil pressure (pilot pressure).

[0035] A discharge oil passage 91 for discharging hydraulic oil is connected to each of the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d. A throttle portion is provided in the discharge oil passage 91. The discharge oil passage 91 merges with a discharge oil passage 92 connected to a discharge port of the operation valve 55 (operation valve 55A, operation valve 55B, operation valve 55C, and operation valve 55D). The discharge oil passage 92 is connected to a discharge portion such as the hydraulic oil tank 22.

[0036] When the travel operating member 59 is swung forward (in the direction of arrow A1 in FIG. 1), the operating valve 55A is operated and pilot pressure is output from the operating valve 55A. This pilot pressure acts on the pressure receiving portion 53a of the left travel pump 53L via the first travel oil passage 45a and also acts on the pressure receiving portion 53a of the right travel pump 53R via the third travel oil passage 45c. This changes the swash plate angles of the left travel pump 53L and the right travel pump 53R, and the left travel motor 36L and the right travel motor 36R rotate forward (forward rotation), causing the work machine 1 to move straight forward.

[0037] Furthermore, when the travel operating member 59 is swung backward (in the direction of the arrow A2 in FIG. 1), the operating valve 55B is operated and pilot pressure is output from the operating valve 55B. This pilot pressure acts on the pressure receiving portion 53b of the left travel pump 53L via the second travel oil passage 45b and also acts on the pressure receiving portion 53b of the right travel pump 53R via the fourth travel oil passage 45d. This changes the swash plate angles of the left travel pump 53L and the right travel pump 53R, and the left travel motor 36L and the right travel motor 36R rotate in the reverse direction (reverse rotation), causing the work machine 1 to move straight backward.

[0038] In addition, when the travel operating member 59 is swung to the right (the direction of the arrow A3 in FIG. 1), the operating valve 55C is operated and pilot pressure is output from the operating valve 55C. This pilot pressure acts on the pressure receiving portion 53a of the left travel pump 53L via the first travel oil passage 45a and also acts on the pressure receiving portion 53b of the right travel pump 53R via the fourth travel oil passage 45d. This changes the swash plate angles of the left travel pump 53L and the right travel pump 53R, causing the left travel motor 36L to rotate forward and the right travel motor 36R to rotate reversely, causing the work machine 1 to spin turn (pivot turn) to the right.

[0039] Furthermore, when the travel operating member 59 is swung to the left (the direction of the arrow A4 in FIG. 1), the operating valve 55D is operated and pilot pressure is output from the operating valve 55D. This pilot pressure acts on the pressure receiving portion 53a of the right travel pump 53R via the third travel oil passage 45c and also acts on the pressure receiving portion 53b of the left travel pump 53L via the second travel oil passage 45b. This changes the swash plate angles of the left travel pump 53L and the right travel pump 53R, causing the left travel motor 36L to rotate in the reverse direction and the right travel motor 36R to rotate in the forward direction, causing the work machine 1 to make a spin turn (pivot turn) to the left.

[0040] In addition, when the travel operating member 59 is swung diagonally, the rotation direction and rotation speed of the left travel motor 36L and the right travel motor 36R are determined by the differential pressure of the pilot pressure acting on the pressure receiving portion 53a and the pressure receiving portion 53b, and the work machine 1 makes a right pivot turn or a left pivot turn while moving forward or backward. In other words, when the travel operating member 59 is swung diagonally forward to the left, the work machine 1 turns left while moving forward at a speed corresponding to the swing angle of the travel operating member 59, when the travel operating member 59 is swung diagonally forward to the right, the work machine 1 turns right while moving forward at a speed corresponding to the swing angle of the travel operating member 59, when the travel operating member 59 is swung diagonally backward to the left, the work machine 1 turns left while moving backward at a speed corresponding to the swing angle of the travel operating member 59, and when the travel operating member 59 is swung diagonally backward to the right, the work machine 1 turns right while moving backward at a speed corresponding to the swing angle of the travel operating member 59.

[0041] Next, the hydraulic system of the working system will be described. As shown in FIG. 2, a plurality of control valves 56 are connected to the second hydraulic pump P2 via oil passages. The plurality of control valves 56 are a boom control valve 56A, a bucket control valve 56B, and a spare control valve 56C. The boom control valve 56A is a pilot-type direct-acting spool-type three-position switching valve, and controls the boom cylinder 14. The bucket control valve 56B is a pilot-type direct-acting spool-type three-position switching valve, and controls the bucket cylinder 15. The spare control valve 56C is a pilot-type direct-acting spool-type three-position switching valve, and controls the hydraulic actuator of the spare attachment. The spare control valve 56C can be switched to a first position 56a, a second position 56b, and a third position 56c by pilot pressure. The third position 56c is a neutral position. The boom 10 and the bucket 11 can be operated by an operating member 51 provided around the driver's seat 8. The operating member 51 is supported so as to be tiltable from a neutral position in the front-to-rear direction, in a width direction perpendicular to the front-to-rear direction, and in an oblique direction. By tilting the operating member 51, operating valves 49A, 49B, 49C, and 49D provided below the operating member 51 can be operated.

[0042] When the operating member 51 is tilted forward, the operating valve 49A is operated and a pilot pressure is output from the operating valve 49A. This pilot pressure acts on a pressure receiving portion of the boom control valve 56A, and the hydraulic oil that has entered the boom control valve 56A is supplied to the rod side of the boom cylinder 14, thereby lowering the booms (boom 10L, boom 10R). When the operating member 51 is tilted rearward, the operating valve 49B is operated and pilot pressure is output from the operating valve 49B. This pilot pressure acts on the pressure receiving portion of the boom control valve 56A, and the hydraulic oil that has entered the boom control valve 56A is supplied to the bottom side of the boom cylinder 14, causing the boom to rise.

[0043] That is, the boom control valve 56A is capable of controlling the flow rate of hydraulic oil flowing to the boom cylinder 14 in accordance with the pressure of hydraulic oil set by operation of the operating member 51 (the pilot pressure set by the operating valve 49A, the pilot pressure set by the operating valve 49B). When the operating member 51 is tilted to the right, the operating valve 49C is operated and pilot oil acts on the pressure receiving portion of the bucket control valve 56B. As a result, the bucket control valve 56B operates in a direction that extends the bucket cylinder 15, and the bucket 11 performs a dump operation at a speed proportional to the amount of tilt of the operating member 51.

[0044] When operating member 51 is tilted to the left, operating valve 49D is operated and pilot oil acts on the pressure receiving portion of bucket control valve 56B. As a result, bucket control valve 56B operates in a direction that contracts bucket cylinder 15, and bucket 11 performs a scooping operation at a speed proportional to the amount of tilt of operating member 51. That is, bucket control valve 56B is capable of controlling the flow rate of hydraulic oil flowing into bucket cylinder 15 in accordance with the pressure of hydraulic oil set by operation of operation member 51 (the pilot pressure set by operation valve 49C, the pilot pressure set by operation valve 49D). In other words, operation valves 49A, 49B, 49C, 49D change the pressure of hydraulic oil in accordance with the operation of operation member 51, and supply the changed hydraulic oil to boom control valve 56A and bucket control valve 56B.

[0045] A supply and discharge oil passage 82 is connected to the standby control valve 56C. The supply and discharge oil passage 82 has an oil passage 82a connected to one of the two ports of the standby control valve 56C and an oil passage 82b connected to the other port. The supply and discharge oil passage 82 (oil passage 82a and oil passage 82b) is connected to the connection member 50, and the hydraulic actuator of the standby attachment can be connected to the connection member 50. Therefore, the standby control valve 56C can supply hydraulic oil to the hydraulic actuator of the standby attachment. The standby control valve 56C is operated by a proportional valve 61 whose opening can be changed according to the pressure of the hydraulic oil. The proportional valve 61 includes a first proportional valve 61A connected to a pressure receiving portion 58C1 of the standby control valve 56C via an oil passage, and a second proportional valve 61B connected to a pressure receiving portion 58C2 of the standby control valve 56C via an oil passage. When the first proportional valve 61A is opened, pilot oil acts on the pressure receiving portion 58C1 through the oil passage. When the second proportional valve 61B is opened, pilot oil acts on the pressure receiving portion 58C2 through the oil passage. Therefore, when pilot oil acts on the pressure receiving portion 58C1 or the pressure receiving portion 58C2 of the auxiliary control valve 56C, the auxiliary control valve 56C is switched, and the hydraulic actuator of the auxiliary attachment is operated by the hydraulic oil supplied from the auxiliary control valve 56C. The first proportional valve 61A and the second proportional valve 61B are operated by the control device 60. The control device 60 is connected to an operating member 78 provided around the driver's seat 8. The operating member 78 is, for example, a rockable seesaw switch, a slidable slide switch, or a push switch that can be pressed. The amount of operation of the operating member 78 is input to the control device 60. The control device 60 outputs a control signal (e.g., a current) to the first proportional valve 61A or the second proportional valve 61B according to the amount of operation of the operating member 78. The proportional valve 61 (first proportional valve 61A, second proportional valve 61B) opens and closes according to the control signal output from the control device 60. Therefore, when the hydraulic oil output to the proportional valve 61 (first proportional valve 61A, second proportional valve 61B) reaches or exceeds a predetermined level, the auxiliary control valve 56C switches to the first position 56a, the second position 56b, or the third position 56c, making it possible to operate the hydraulic attachment.

[0046] 2, a hydraulic lock valve 75 is provided in the discharge oil passage 40 that connects the first hydraulic pump P1 and the operation valves 49A, 49B, 49C, and 49D. The hydraulic lock valve 75 is a two-position switching valve that switches between a first position 75a and a second position 75b. When the hydraulic lock valve 75 is in the first position 75a, the supply of hydraulic oil to the operation valves 49A, 49B, 49C, and 49D is cut off, and when the hydraulic lock valve 75 is in the second position 75b, the supply of hydraulic oil to the operation valves 49A, 49B, 49C, and 49D is allowed.

[0047] 1, the hydraulic system of the work machine is provided with a connecting oil passage 100. The connecting oil passage 100 is an oil passage that connects at least two of 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 connecting oil passage 100 connects the forward pressure receiving portion (first pressure receiving portion, third pressure receiving portion) 53a of the travel pump 53L and the right travel pump 53R to the reverse pressure receiving portion (second pressure receiving portion, fourth pressure receiving portion) 53b of each of the travel pumps 53L and 53R in the travel oil passage 45. That is, the connecting oil passage 100 connects either the first travel oil passage 45a or the third travel oil passage 45c to either the second travel oil passage 45b or the fourth travel oil passage 45d. More specifically, the connecting oil passage 100 includes a first connecting passage 100a that connects the first travel oil passage 45a and the fourth travel oil passage 45d, and a second connecting passage 100b that connects the second travel oil passage 45b and the third travel oil passage 45c. A throttle portion 101 is provided in the connecting oil passage 100. Specifically, the throttle portion 101 is provided in both the first connecting passage 100a and the second connecting passage 100b.

[0048] [Second embodiment] FIG. 3 shows a hydraulic system of a work machine in the second embodiment. As shown in FIG. 3, the hydraulic system of the work machine includes an actuating valve 69 . The actuating valve 69 is a valve that can change the pilot pressure of the pilot oil that operates the travel pumps (left travel pump 53L, right travel pump 53R). The actuating valve 69 and the operating device 54 are connected by the first oil passage 40a. More specifically, the actuating valve 69 is provided in the middle of the discharge oil passage 40, and the section of the discharge oil passage 40 that connects the actuating valve 69 and the operating device 54 is the first oil passage 40a.

[0049] The actuating valve 69 changes the pilot pressure (actuating pilot pressure acting on pressure receiving parts 53a, 53b) of the pilot oil that operates the travel pumps (left travel pump 53L, right travel pump 53R) by changing the opening degree. For example, the actuating valve 69 is an electromagnetic proportional valve whose opening degree can be changed based on a control signal (for example, voltage, current) of the control device 60. The actuating valve 69 is a valve whose opening degree increases as the value of the control signal (control value) increases and whose opening degree decreases as the control value decreases.

[0050] When the load on the prime mover 32 is high, the control device 60 performs control to prevent engine stall (anti-stall control) by controlling the operating valve 69. That is, the control device 60 performs anti-stall control in accordance with the load on the prime mover 32. For example, when the drop amount, which is the difference between the target rotation speed set by the accelerator 65 and the actual rotation speed detected by the rotation detection device 68, is equal to or greater than the threshold value, the load on the prime mover 32 is high, and the control device 60 performs anti-stall control. In the anti-stall control, the opening degree of the operating valve 69 shown in FIG. 3 is reduced to reduce the output of the traveling pumps (left traveling pump 53L, right traveling pump 53R). That is, the control device 60 outputs a control signal to the operating valve 69 to excite the solenoid of the operating valve 69, thereby changing the pilot pressure (traveling primary pressure) from the operating valve 69 to the operating device 54. As a result, the pilot pressure that operates the traveling pumps (left traveling pump 53L, right traveling pump 53R) is changed.

[0051] 4 is a diagram showing an example of a control map showing the relationship between the primary traveling pressure and the rotation speed of the prime mover in the anti-stall mode. In the control map shown in FIG. 4, the primary traveling pressure is determined according to the opening degree of the actuated valve 69, so there is a correlation between the primary traveling pressure and the magnitude of the control signal output to the actuated valve 69, and the primary traveling pressure can be replaced with the control signal. In other words, the primary traveling pressure on the vertical axis of the control map can be read as the control signal. The control map is stored in the storage unit 63.

[0052] The control device 60 calculates a drop amount, which is the difference between the target rotation speed set by the accelerator 65 and the actual rotation speed detected by the rotation detection device 68. When the drop amount is less than a threshold value, the control device 60 sets a control value indicated by a control signal according to the rotation speed of the prime mover (target rotation speed or actual rotation speed) so as to match line L1 of the control map. On the other hand, when the drop amount is equal to or greater than the threshold, the control device 60 sets the control value of the control signal according to the rotation speed of the prime mover (target rotation speed or actual rotation speed) so as to coincide with line L2 of the control map. That is, the control device 60 sets the control values ​​of the current value, voltage value, etc. based on the control map.

[0053] Therefore, in the anti-stall control, a control value is set based on the line L2, and a control signal indicating the control value is output to the operating valve 69, thereby making it possible to keep the pilot pressure (travel primary pressure) of the hydraulic oil entering the operating valve 55 low. As a result, the swash plate angles of the travel pumps (left travel pump 53L, right travel pump 53R) are adjusted, the load acting on the prime mover 32 is reduced, and it is possible to prevent the engine from stalling. Note that, although one line L2 is shown in FIG. 4, there may be multiple lines L2.

[0054] 3, the first oil passage 40a is provided with a second oil passage 110. The second oil passage 110 is an oil passage that connects at least the first travel oil passage 45a and the third travel oil passage 45c to the first oil passage 40a. The second oil passage 110 includes a first connection passage 110a and a second connection passage 110b. The first connection passage 110a is an oil passage connected to the first oil passage 40a and extending toward the first running oil passage 45a and the third running oil passage 45c. The second connection passage 110b is an oil passage branched off from the first connection passage 110a and connected to the first running oil passage 45a and the third running oil passage 45c.

[0055] A check valve 111 is provided in the middle of the first connection passage 110a. The check valve 111 is a valve that allows the hydraulic oil to flow from the first travel oil passage 45a and the third travel oil passage 45c toward the first oil passage 40a and prevents the hydraulic oil from flowing from the first oil passage 40a toward the first travel oil passage 45a and the third travel oil passage 45c. As shown in FIG. 3, a throttle portion 103 is provided in the travel oil passages 45 (the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d).

[0056] 5A, in the second connection passage 110b, an oil passage 112 connecting both end sides of the check valve 111 may be provided, and a throttle section 113 may be provided in the oil passage 112. As shown in FIG 5B, in the discharge oil passage 40, an oil passage 115 connecting the operating valve 69 side and the hydraulic lock valve 75 may be provided, a check valve 116 may be provided in the oil passage 115, an oil passage 117 connecting both end sides of the check valve 116 may be provided, and a throttle section 118 may be provided in the oil passage 117.

[0057] In the above-described embodiment, as shown in Figures 3 and 5A, the throttling section 103 was provided downstream of the connecting oil passage 100 in the running oil passage 45 (first running oil passage 45a, second running oil passage 45b, third running oil passage 45c, fourth running oil passage 45d). However, instead, the throttling section 103 may be provided upstream of the connecting oil passage 100, i.e., between the connecting oil passage 100 and the high pressure selection valve (47a-47d).

[0058] [Third embodiment] Fig. 6 shows a hydraulic system of a work machine of a third embodiment. The hydraulic system of the work machine of Fig. 6 includes a switching valve (operation switching valve) 150 that switches between vibration damping operation and float operation. The switching valve 150 is a three-position switching valve that can be switched to a first position 150a, a second position 150b, and a neutral position 150c. The switching valve 150 performs a float operation when in the first position 150a, performs a vibration damping operation when in the second position 150b, and stops the vibration damping operation and the float operation when in the neutral position 150c.

[0059] The switching valve 150 will be described in detail below. The switching valve 150 has a first port 151, a second port 152, a third port 153, a fourth port 154, and a fifth port 155. A first communication passage 161 is connected to the first port 151. A second communication passage 162 is connected to the second port 152. A discharge oil passage 124 leading to the hydraulic oil tank 22 is connected to the third port 153 and the fourth port 154. An accumulator 156, which is a pressure accumulation device, is connected to the fifth port 155.

[0060] The switching valve 150 is a pilot-type switching valve incorporating a solenoid valve (electromagnetic proportional valve), and includes a pressure-receiving portion 150A that receives hydraulic oil (pilot oil), a pressure-receiving portion 150B that receives pilot oil, a first solenoid 150C, and a second solenoid 150D. The pressure-receiving portion 150A is disposed on one side of the spool in the longitudinal direction, and the pressure-receiving portion 150B is disposed on the other side of the spool in the longitudinal direction. An oil passage (pilot supply passage) 123 leading to the first hydraulic pump P1 is connected to the pressure-receiving portion 150A and the pressure-receiving portion 150B, and the hydraulic oil (pilot oil) is supplied to the pressure-receiving portion 150A and the pressure-receiving portion 150B.

[0061] When the first solenoid 150C is excited, the pilot pressure received by the pressure receiving portion 150A acts on the spool, and the spool moves in one direction, switching the switching valve 150 to the first position 150a. When the second solenoid 150D is excited, the pilot pressure received by the pressure receiving portion 150B acts on the spool, and the spool moves in the other direction, switching the switching valve 150 to the second position 150b. When either the first solenoid 150C or the second solenoid 150D is de-energized, the spool remains in the neutral position, and the switching valve 150 is switched to the neutral position 150c.

[0062] When the switching valve 150 is in the first position 150a, the first port 151 and the fourth port 154 are connected by a spool. As a result, the hydraulic oil in the first oil chamber 14f of the boom cylinder 14 is discharged to the discharge oil passage 124 through the first communication passage 161, the first port 151, and the fourth port 154. Also, when the switching valve 150 is in the first position 150a, the second port 152 and the third port 153 are connected by a spool. As a result, the hydraulic oil in the second oil chamber 14g of the boom cylinder 14 is discharged to the discharge oil passage 124 through the second communication passage 162, the second port 152, and the third port 153. That is, when the switching valve 150 is in the first position 150a, the first communication passage 161 and the second communication passage 162 can be connected to the discharge oil passage 124 by the spool, and by discharging the hydraulic oil of the boom cylinder 14 to the discharge oil passage 124, float operation becomes possible.

[0063] Moreover, when the switching valve 150 is in the second position 150b, the first port 151 and the fifth port 155 are connected by the spool. As a result, the boom cylinder 14 is connected to the accumulator 156 through the first communication passage 161, the first port 151, and the fifth port 155. Moreover, when the switching valve 150 is in the second position 150b, the second port 152 and the third port 153 are connected by the spool, and the hydraulic oil of the boom cylinder 14 is discharged to the discharge oil passage 124 through the second communication passage 162, the second port 152, and the third port 153. That is, when the switching valve 150 is in the second position 150b, the first communication passage 161 and the accumulator 156 can be communicated with each other and the second communication passage 162 and the discharge oil passage 124 can be communicated with each other by the spool, and vibration damping operation can be performed. In this way, by performing vibration damping operation, even if the bucket 11 vibrates up and down when the work machine 1 is traveling, the accumulator 156 can absorb the pressure fluctuations in the first oil chamber 14f of the boom cylinder 14, making it possible to suppress vibrations of the work machine 1 when traveling.

[0064] The switching control of the switching valve 150 is performed by a control device 60. A first switch 191 and a second switch 192 are connected to the control device 60. The first switch 191 and the second switch 192 are provided in the vicinity of the driver's seat 8. An operator seated in the driver's seat 8 can operate the first switch 191 and the second switch 192. The first switch 191 is a switch that switches between on and off, and when it is on, it issues a first command for float operation to the control device 60. When it is off, the first switch 191 does not issue the first command to the control device 60. When the control device 60 acquires the first command of the first switch 191, it outputs a control signal to the first solenoid 150C of the switching valve 150 to excite the first solenoid 150C. Furthermore, when the control device 60 has not acquired the first command of the first switch 191 (off), it outputs a control signal to the first solenoid 150C of the switching valve 150 to demagnetize the first solenoid 150C.

[0065] The second switch 192 is a switch that switches between on and off, and when it is on, it issues a second command for vibration suppression operation to the control device 60. When it is off, the second switch 192 does not issue the second command to the control device 60. When the control device 60 acquires the second command of the second switch 192, it outputs a control signal to the second solenoid 150D of the switching valve 150 to excite the second solenoid 150D. Furthermore, when the control device 60 has not acquired the second command of the second switch 192 (off), it outputs a control signal to the second solenoid 150D of the switching valve 150 to demagnetize the second solenoid 150D.

[0066] When the first switch is changed from off to on while the second switch 192 is on and vibration damping operation is being performed, the control device 60 stops vibration damping control by turning on the second switch 192. In other words, when the first switch 191 is turned on and the first command is input in a situation where the second solenoid 150D is excited by the second command (the switching valve 150 is at the second position 150b), the control device 60 prioritizes the first command over the second command, and demagnetizes the second solenoid 150D even if the second switch 192 is on, while exciting the first solenoid 150C to switch the switching valve 150 to the first position 150a.

[0067] According to the control device 60, the first switch 191 and the second switch 192 can be used to easily switch between float operation and vibration damping operation, but when commands are given for both float operation and vibration damping operation, the float operation is given priority, allowing the work machine 1 to perform work efficiently. In addition, because the switching valve (operation switching valve) 150 is configured to switch between vibration damping operation and float operation, the switching valve 150 can reduce the amount of hydraulic oil discharged from the switching valve, compared to a case in which both switching valves for switching vibration damping operation and switching float operation are operated simultaneously in a hydraulic circuit in which both switching valves are separately configured.

[0068] In addition, in a hydraulic circuit in which a switching valve for switching vibration damping operation and a switching valve for switching float operation are separately configured, there is a leakage amount from the switching valve when vibration damping operation is stopped, and a leakage amount from the switching valve when float operation is stopped, and the leakage amount is the combined leakage amount (total leakage amount) of both. On the other hand, since the switching valve (operation switching valve) 150 is a single valve that switches between vibration damping operation and float operation, the leakage amount from the switching valve 150 can be made smaller than the total leakage amount.

[0069] Moreover, the number of components of the switching valve 150 can be reduced compared to when a switching valve for switching the vibration damping operation and a switching valve for switching the float operation are configured. Fig. 7A is a diagram showing a part of the inside of the switching valve 150 by a hydraulic circuit. That is, the switching valve 150 shown in Fig. 6 is equivalent to the switching valve 150 shown in Fig. 7A. As shown in Fig. 7A, a pilot supply passage 123 is connected to a first solenoid valve 157A having a first solenoid 150C and a second solenoid valve 157B having a second solenoid 150D. The first solenoid valve 157A and the pressure receiving portion 150A are connected by a first internal oil passage 165, and the second solenoid valve 157B and the pressure receiving portion 150B are connected by a second internal oil passage 166. Note that Fig. 7A shows a schematic diagram of a spool 158.

[0070] 7A, in spool 158, pressure receiving portion 150A of spool 158 and pressure receiving portion 150B of spool 158 are communicated with each other through communication oil passage 197. A throttle portion 199 having a small inner diameter is formed in the middle of communication oil passage 197. Note that there is no limitation to the type of throttle portion 199, and a plurality of throttle portions 199 may be provided in communication oil passage 197, or the throttle portions 199 may be asymmetric. Also, as shown in FIG. 7B, the first internal oil passage 165 and the second internal oil passage 166 may be communicated with each other through a communication oil passage 198.

[0071] As described above, according to the third embodiment, in the switching valve 150, the pressure receiving portion 150A on one side and the pressure receiving portion 150B on the other side are communicated with each other through the communication oil passages 197, 198, so that it is possible to reduce the impact when the spool 158 (switching valve 150) is operated, and it is possible to improve the operability. In other words, it is possible to reduce the moving speed (stroke speed) of the spool 158, and it is possible to improve the operability.

[0072] The work machine 1 includes a body 2, a left traveling device 5L provided on the left side of the body 2, a right traveling device 5R provided on the right side of the body 2, a left traveling motor 36L capable of transmitting power to the left traveling device 5L, and a right traveling motor 36R capable of transmitting power to the right traveling device 5R. The pressure receiving portion 53a is a first pressure receiving portion 53b. When hydraulic oil acts on the first pressure receiving portion 53a Left drive motor 36L Forward Let When the hydraulic oil acts on the second pressure receiving portion 53b, Left drive motor 36L Reversal Let The left travel pump 53L, The pressure receiving portion 53a is connected to a third pressure receiving portion 53b. When hydraulic oil acts on the third pressure receiving portion 53a Right travel motor 36R Forward Let When the hydraulic oil acts on the fourth pressure receiving portion 53b, Right travel motor 36R Reversal Let Right travel pump 53Ra travel operating device 54 that applies hydraulic oil to at least one of a first pressure receiving portion 53a, a second pressure receiving portion 53b, a third pressure receiving portion 53a, and a fourth pressure receiving portion 53b when the travel operating member 59 is operated; a first travel oil passage 45a that is connected to the first pressure receiving portion 53a and that passes hydraulic oil that acts on the first pressure receiving portion 53a when the travel operating member 59 is operated; and a second travel oil passage 45a that is connected to the second pressure receiving portion 53b and that passes hydraulic oil that acts on the second pressure receiving portion 53b when the travel operating member 59 is operated. 5b, a third travel oil passage 45c connected to the third pressure receiving portion 53a and passing hydraulic oil acting on the third pressure receiving portion 53a when the travel operation member 59 is operated, a fourth travel oil passage 45d connected to the fourth pressure receiving portion 53b and passing hydraulic oil acting on the fourth pressure receiving portion 53b when the travel operation member 59 is operated, and a connecting oil passage 100 connecting at least two travel oil passages among the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d. According to this, for example, among the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d, the hydraulic oil flows from the travel oil passage on one side with a high pressure to the travel oil passage on the other side with a low pressure through the connecting oil passage 100, thereby improving the operability of the travel operation when the travel operation member 59 is operated.

[0073] The connecting oil passage 100 connects either the first travel oil passage 45a or the third travel oil passage 45c to either the second travel oil passage 45b or the fourth travel oil passage 45d. left The forward rotation side pressure receiving portion (first pressure receiving portion, third pressure receiving portion) 53a of each of the travel pump 53L and the right travel pump 53R is connected to the reverse rotation side pressure receiving portion (second pressure receiving portion, fourth pressure receiving portion) 53b. For example, when making a left pivot turn while traveling forward, hydraulic oil (pilot oil) is supplied from the second travel oil passage 45b to the third travel oil passage 45c via the connecting oil passage 100. The faster the speed before traveling, the more pilot oil is supplied to the third travel oil passage 45c via the connecting oil passage 100, and therefore the pressure of the second pressure receiving portion 53b of the left travel pump 53L becomes higher, thereby improving the operating feel.

[0074] In addition, when the work machine 1 is moving forward, the hydraulic oil flows from both the first traveling oil passage 45a and the third traveling oil passage 45c to the second traveling oil passage 45b and the fourth traveling oil passage 45d via the connecting oil passage 100, so the pilot pressure acting on the pressure receiving portion of the traveling pump (left traveling pump 53L, right traveling pump 53R) is low. On the other hand, for example, when making a pivot turn to the left, the pilot pressure of the second traveling oil passage 45b increases, and pilot oil is less likely to flow from the third traveling oil passage 45c to the connecting oil passage 100, so the pilot pressure of the third traveling oil passage 45c tends to be high in response to the operation of the operating member 59 (the pressure acting on the third pressure receiving portion 53a on the forward side of the right traveling pump 53R is high). As a result, in a pivot turn, it is possible to suppress a decrease in the rotation speed of the traveling motor on the outside of the turn, and the travelability can be improved.

[0075] The connecting oil passage 100 includes a first connecting passage 100a connecting the first traveling oil passage 45a and the fourth traveling oil passage 45d, and a second connecting passage 100b connecting the second traveling oil passage 45b and the third traveling oil passage 45c. This makes it possible to improve the operability of the work machine 1 with a simple configuration. The work machine 1 is equipped with an actuated valve 69 that can change the pressure of the hydraulic oil supplied to the travel operation device 54, and a first oil passage 40a that connects the travel operation device 54 and the actuated valve 69. According to this, when engine stall is suppressed by the actuated valve 69, the hydraulic oil in the travel oil passage 45 can be discharged via the connecting oil passage 100, so that the pilot pressure of the travel oil passage 45 can be quickly reduced and the responsiveness of the travel pumps (left travel pump 53L, right travel pump 53R) can be improved.

[0076] The work machine 1 includes the first travel oil passage 45a and the third travel oil passage 45c, and the second oil passage 110 that connects the first oil passage 40a. With this, the hydraulic oil (pilot oil) in the travel oil passage 45 (the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the third travel oil passage 45d) can be discharged to the operating valve 69 side via the second oil passage 110, and when the engine stall is suppressed by the operating valve 69, the pilot pressure in the travel oil passage 45 can be quickly reduced, and the responsiveness of the travel pumps (the left travel pump 53L and the right travel pump 53R) can be improved.

[0077] The connecting oil passage 100 is provided with a throttle portion 101. This makes it possible to stabilize the pressure change of the pilot oil in the travel oil passage 45 (the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the third travel oil passage 45d). The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0078] 1: Work equipment 2: Aircraft 5L: Left running device 5R: Right running gear 36L: Left drive motor 36R: Right drive motor 40a: No. 1 oil road 41: Oil road 45: Traveling oil road 45a: 1st traveling oilway 45b: 2nd travel oilway 45c: 3rd travel oilway 45d: 4th running oil road 45d: 3rd traveling oilway 51: Operation member 53L: Left travel pump 53R: Right travel pump 53a: First pressure receiving part, third pressure receiving part 53b: second pressure receiving part, fourth pressure receiving part 54: Driving operation device 69: Actuated valve 100: Connecting oil path 100a: First connecting road 100b: 2nd connecting road 101: Squeezing section 103: Squeezing section 110: 2nd oil road

Claims

1. The aircraft and A left running device provided on the left side of the aircraft body; A right running device provided on the right side of the aircraft body; a left traveling motor capable of transmitting power to the left traveling device; a right traveling motor capable of transmitting power to the right traveling device; a left traveling pump having a first pressure receiving portion and a second pressure receiving portion, the left traveling motor being rotated in a forward direction when hydraulic oil acts on the first pressure receiving portion and being rotated in a reverse direction when hydraulic oil acts on the second pressure receiving portion; a right traveling pump having a third pressure receiving portion and a fourth pressure receiving portion, the right traveling motor being rotated in a forward direction when hydraulic oil acts on the third pressure receiving portion and being rotated in a reverse direction when hydraulic oil acts on the fourth pressure receiving portion; a travel operation device that applies hydraulic oil to at least any one of the first pressure receiving portion, the second pressure receiving portion, the third pressure receiving portion, and the fourth pressure receiving portion when a travel operation member is operated; a first travel oil passage connected to the first pressure receiving portion and passing hydraulic oil acting on the first pressure receiving portion when a travel operating member is operated; a second travel oil passage connected to the second pressure receiving portion and passing hydraulic oil acting on the second pressure receiving portion when a travel operating member is operated; a third travel oil passage connected to the third pressure receiving portion and passing hydraulic oil acting on the third pressure receiving portion when a travel operating member is operated; a fourth travel oil passage connected to the fourth pressure receiving portion and passing hydraulic oil acting on the fourth pressure receiving portion when a travel operating member is operated; A connecting oil passage that connects at least two of the first travel oil passage, the second travel oil passage, the third travel oil passage, and the fourth travel oil passage; A throttle portion provided in the connecting oil passage; Equipped with The connecting oil passage includes a first connecting passage that connects the first travel oil passage and the fourth travel oil passage, and a second connecting passage that connects the second travel oil passage and the third travel oil passage, A work machine, wherein the throttle portion is provided in both the first connecting passage and the second connecting passage.

2. an actuation valve capable of changing a pressure of hydraulic oil supplied to the traveling operation device; A first oil passage connecting the traveling operation device and the actuation valve; The work machine according to claim 1 , further comprising:

3. 3. The work machine according to claim 2, further comprising a second oil passage that connects the first oil passage with the first and third travel oil passages.

Images