JP2020169527A - Work machine - Google Patents

Abstract

To make it possible to suitably perform automatic deceleration depending on the rotation speed of an engine.SOLUTION: A work machine comprises: a traveling pressure detection device that detects pressure in a connection oil passage as traveling pressure; a rotation speed detection device that detects an engine speed that is the number of rotation of the engine; a first storage device that stores a first deceleration determination table that indicates the relationship between engine speeds and first deceleration determination pressure; and a control device that has an automatic deceleration unit that performs automatic deceleration for automatically decelerating at least one of a pair of traveling motors from a second speed to a first speed when at least one of the pair of traveling motors is at the second speed. The automatic deceleration unit extracts first deceleration determination pressure using the engine speed detected by the rotation speed detection device, and the first deceleration determination table when at least one of the pair of traveling motors is at the second speed. When the traveling pressure that is detected by the traveling pressure detection device is above the extracted first deceleration determination pressure, the automatic deceleration unit performs automatic deceleration.SELECTED DRAWING: Figure 1

Description

The present invention relates to working machines such as skid steer loaders, compact truck loaders, and backhoes, for example.

Conventionally, there is a technique described in Patent Document 1 as a technique for decelerating and increasing the speed of a working machine. The working machine of Patent Document 1 includes a traveling motor capable of changing between a first speed and a second speed higher than the first speed, and a traveling switching valve capable of switching the speed of the traveling motor. In the case of two speeds, automatic deceleration is performed in which the traveling motor is decelerated to the first speed when the pressure of the hydraulic oil supplied to the traveling device is equal to or higher than a predetermined speed.

Japanese Unexamined Patent Publication No. 2008-82130

In the working machine of Patent Document 1, when the pressure of the hydraulic oil supplied to the traveling device is equal to or higher than a predetermined speed, the speed can be reduced from the second speed to the first speed, but the automatic deceleration can be switched depending on the rotation speed of the prime mover. It may not be done at the intended timing.
The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a working machine capable of appropriately performing automatic deceleration according to the rotation speed of the prime mover. ..

The technical measures taken by the present invention to solve the technical problems are as follows.
The working machine can transmit power to the machine body, the motor, a pair of traveling devices provided on the left and right sides of the machine body, and the left traveling device and the right traveling device, respectively, and has a first speed. A pair of traveling motors that can be switched to a second speed faster than the first speed, a pair of traveling pumps that are driven by the power of the prime mover and supply hydraulic oil to each of the pair of traveling motors, and the above. A connecting oil passage connecting the pair of traveling motors and the pair of traveling pumps, a traveling pump pressure detecting device that detects the pressure of the connecting oil passage as a traveling pump pressure, and a prime mover rotation speed which is the rotation speed of the prime mover. A third storage device that stores a second deceleration determination table showing the relationship between the prime mover rotation speed and the second deceleration determination pressure, and at least one of the pair of traveling motors One-way running, which is the running pump pressure when one of the pair of running motors is driven, and the automatic deceleration unit that automatically decelerates from the second speed to the first speed when the speed is two. A control device including a differential pressure calculation unit for calculating a traveling differential pressure which is a difference between the pump pressure and the other traveling pump pressure which is the traveling pump pressure when the other of the pair of traveling motors is driven. , The second deceleration unit is based on the prime mover rotation speed detected by the rotation speed detection device and the second deceleration determination table when at least one of the pair of traveling motors is at the second speed. The deceleration determination pressure is extracted, and when the traveling differential pressure calculated by the differential pressure calculation unit is equal to or greater than the extracted second deceleration determination pressure, the automatic deceleration is performed.

One of the traveling motors of the pair of traveling motors includes a first port connected to the connecting oil passage and a second port connected to the connecting oil passage, and the other traveling motor of the pair of traveling motors. Includes a third port connected to the connecting oil passage and a fourth port connected to the connecting oil passage, and the traveling pump pressure detecting device detects the pressure of the connecting oil passage on the first port side. The first pressure detecting device that detects the traveling pump pressure as the first traveling pump pressure, and the traveling pump pressure detecting device obtains the traveling pump pressure that detects the pressure of the connecting oil passage on the second port side. The second pressure detecting device for detecting the two traveling pump pressures and the traveling pump pressure detecting device detect the traveling pump pressure for detecting the pressure of the connecting oil passage on the third port side as the third traveling pump pressure. The third pressure detecting device and the traveling pump pressure detecting device include a fourth pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the fourth port side as the fourth traveling pump pressure. The differential pressure calculation unit includes, as the traveling differential pressure, a first differential pressure which is a difference between the first traveling pump pressure and the third traveling pump pressure, and the second traveling pump pressure and the first traveling pump pressure. 4 When any of the second differential pressure, which is the difference from the traveling pump pressure, is obtained, and the automatic deceleration unit has either the first differential pressure or the second differential pressure equal to or higher than the second deceleration determination pressure. In addition, the automatic deceleration is performed.

The third storage device stores a second deceleration determination table in which the second deceleration determination pressure increases as the prime mover rotation speed increases.
The working machine can transmit power to the machine body, the prime mover, a pair of traveling devices provided on the left and right sides of the machine body, and the left traveling device and the right traveling device, respectively, and has a first speed. A pair of traveling motors that can be switched to a second speed faster than the first speed, a pair of traveling pumps that are driven by the power of the prime mover and supply hydraulic oil to each of the pair of traveling motors, and the above. A connecting oil passage connecting the pair of traveling motors and the pair of traveling pumps, a traveling pump pressure detecting device that detects the pressure of the connecting oil passage as a traveling pump pressure, and a prime mover rotation speed which is the rotation speed of the prime mover. A rotation speed detection device for detecting the above and a fourth storage device for storing a second return determination table showing the relationship between the prime mover rotation speed and the second return determination pressure, and at least one of the pair of traveling motors One of the automatic deceleration unit that automatically decelerates from the second speed to the first speed when it is the second speed, and the traveling pump pressure when one of the pair of traveling motors is driven. A control device having a traveling pump pressure and a differential pressure calculating unit for calculating a traveling differential pressure which is a difference between the traveling pump pressure when the other of the pair of traveling motors is driven and the other traveling pump pressure. The automatic deceleration unit extracts the second return determination pressure from the motor rotation speed detected by the rotation speed detection device and the second return determination table after the automatic deceleration, and the differential pressure calculation unit When the calculated traveling differential pressure after automatic deceleration is equal to or less than the extracted second return determination pressure, at least one of the pair of traveling motors is restored from the first speed to the second speed. ..

As the traveling differential pressure, the differential pressure calculation unit includes a first differential pressure which is a difference between the first traveling pump pressure and the third traveling pump pressure, the second traveling pump pressure, and the fourth traveling pump pressure. The second differential pressure, which is the difference between the two, is obtained, and the automatic deceleration unit is at least one of the pair of traveling motors when the first differential pressure and the second differential pressure are equal to or less than the second return determination pressure. Returns from the first speed to the second speed.

The fourth storage device stores a second return determination table in which the second return determination pressure increases as the prime mover rotation speed increases.

According to the present invention, automatic deceleration can be appropriately performed according to the rotation speed of the prime mover.

It is a figure which shows the hydraulic system (hydraulic circuit) of a work machine. It is a figure which shows the display device. It is a figure which shows the other display device. It is a flow which shows the operation of a control device and a display device. It is a figure which shows the 1st deceleration determination table T1. It is a figure which shows the 1st return determination table U1. It is a figure which shows the 1st process in an automatic deceleration part. It is a figure which shows the 2nd deceleration determination table T2. It is a figure which shows the 2nd return determination table U2. It is a figure which shows the 2nd process in an automatic deceleration part. It is a figure which shows the 3rd deceleration determination table T3. It is a figure which shows the 3rd return determination table U3. It is a figure which shows the 3rd process in an automatic deceleration part. It is a figure which shows the 4th deceleration determination table T4. It is a figure which shows the 4th return determination table U4. It is a figure which shows the 4th process in an automatic deceleration part. It is a figure which shows the hydraulic system provided with the anti-stall valve. It is a figure which shows the relationship between the prime mover rotation speed, the secondary pilot pressure, and control lines L1 and L2. It is a figure which shows the 5th deceleration determination table T5. It is a figure which shows the 5th return determination table U5. It is a figure which shows the 5th process in an automatic deceleration part. It is a figure which shows the 6th deceleration determination table T6. It is a figure which shows the 6th return determination table U6. It is a figure which shows the 6th process in an automatic deceleration part. It is a side view which shows the truck loader which is an example of a working machine.

Hereinafter, a hydraulic system for a working machine according to the present invention and a preferred embodiment of a working machine provided with this hydraulic system will be described with reference to the drawings as appropriate.
FIG. 18 shows a side view of the working machine according to the present invention. FIG. 18 shows a compact truck loader as an example of a working machine. However, the working machine according to the present invention is not limited to the compact truck loader, and may be, for example, another type of loader working machine such as a skid steer loader. Further, it may be a work machine other than the loader work machine.

As shown in FIG. 18, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a pair of traveling devices 5L and 5R. In the embodiment of the present invention, the front side (left side of FIG. 18) of the driver seated in the driver's seat 8 of the work machine 1 is the front, the rear side of the driver (right side of FIG. 18) is the rear, and the left side of the driver (FIG. 18). The front side of 18 will be described as the left side, and the right side of the driver (the back side of FIG. 18) will be described as the right side. Further, the horizontal direction, which is a direction orthogonal to the front-rear direction, will be described as the body width direction. The direction from the central portion of the aircraft 2 toward the right or left portion will be described as the outer side of the aircraft. In other words, the outside of the airframe is the width direction of the airframe and the direction away from the airframe 2. The direction opposite to the outside of the aircraft will be described as the inside of the aircraft. In other words, the inside of the machine is the width direction of the machine and the direction approaching the body 2.

The cabin 3 is mounted on the airframe 2. The cabin 3 is provided with a driver's seat 8. The working device 4 is attached to the machine body 2. The pair of traveling devices 5L and 5R are provided on the outside of the machine body 2. A prime mover 32 is mounted on the rear part of the machine body 2.
The working device 4 has a boom 10, a working tool 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

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

The front parts of the left and right booms 10 are connected by a deformed connecting pipe. The bases (rear parts) 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 side and the right side of the machine body 2, respectively, corresponding to the left and right booms 10.
The lift link 12 is provided vertically at the rear of the base of each boom 10. The upper portion (one end side) of the lift link 12 is rotatably supported around the lateral axis via a pivot shaft 16 (first pivot shaft) near the rear portion of the base of each boom 10. Further, the lower portion (the other end side) of the lift link 12 is rotatably and rotatably supported around the lateral axis via the pivot shaft 17 (second pivot shaft) toward the rear portion of the airframe 2. The second pivot shaft 17 is provided below the first pivot shaft 16.

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

The control link 13 is provided in front of the lift link 12. One end of the control link 13 is rotatably supported around a horizontal axis via a pivot shaft 20 (fifth pivot shaft). The fifth pivot shaft 20 is the airframe 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 shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is a boom 10 and is provided in front of the second pivot shaft 17 and above the second pivot shaft 17.

By expanding and contracting the boom cylinder 14, each boom 10 swings up and down around the first pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and the control link 13, and the tip of each boom 10 Goes up and down. The control link 13 swings up and down around the fifth pivot shaft 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the second pivot shaft 17 as the control link 13 swings up and down.

Another work tool can be attached to the front part of the boom 10 instead of the bucket 11. Another working tool is, for example, an attachment (spare attachment) such as a hydraulic crusher, a hydraulic breaker, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower.
A connecting member 50 is provided on the front portion of the boom 10 on the left side. The connecting member 50 is a device for connecting the hydraulic device mounted on the spare attachment and the first pipe material such as a pipe provided on the boom 10. Specifically, the first pipe material can be connected to one end of the connecting member 50, and the second pipe material connected to the hydraulic device of the spare attachment can be connected to the other end. As a result, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The bucket cylinder 15 is arranged near the front of each boom 10. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
Of the pair of traveling devices 5L and 5R, the traveling device 5L is provided on the left side of the machine body 2, and the traveling device 5R is provided on the right side of the machine body 2. As the pair of traveling devices 5L and 5R, a crawler type (including a semi-crawler type) traveling device is adopted in the present embodiment. A wheel-type traveling device having front wheels and rear wheels may be adopted. Hereinafter, for convenience of explanation, the traveling device 5L may be referred to as a left traveling device 5L, and the traveling device 5R may be referred to as a right traveling device 5R.

The prime mover 32 is an internal combustion engine such as a diesel engine or a gasoline engine, an electric motor, or the like. In this embodiment, the prime mover 32 is, but is not limited to, a diesel engine.
Next, the hydraulic system of the working machine will be described.
As shown in FIG. 1, the hydraulic system of the working 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 the prime mover 32, and is composed of a constant capacity type gear pump. The first hydraulic pump P1 can discharge the hydraulic oil stored in the tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 for storing the hydraulic oil may be referred to as a hydraulic oil tank. Further, among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

The second hydraulic pump P2 is a pump driven by the power of the prime mover 32, and is composed of a constant capacity type gear pump. The second hydraulic pump P2 can discharge the hydraulic oil stored in the tank 22, and supplies the hydraulic oil to, for example, the oil passage of the working system. For example, the second hydraulic pump P2 supplies hydraulic oil to the boom cylinder 14 that operates the boom 10, the bucket cylinder 15 that operates the bucket, and the control valve (flow control valve) that controls the preliminary hydraulic actuator that operates the preliminary hydraulic actuator. To do.

Further, the hydraulic system of the working machine includes a pair of traveling motors 36L and 36R and a pair of traveling pumps 53L and 53R. The pair of traveling motors 36L and 36R are motors that transmit power to the pair of traveling devices 5L and 5R. Of the pair of traveling motors 36L and 36R, one traveling motor 36L transmits rotational power to the traveling device (left traveling device) 5L, and the other traveling motor 36R rotates to the traveling device (right traveling device) 5R. To transmit the power of.

The pair of traveling pumps 53L and 53R are pumps driven by the power of the prime mover 32, and are, for example, swash plate type variable displacement axial pumps. By driving the pair of traveling pumps 53L and 53R, hydraulic oil is supplied to the pair of traveling motors 36L and 36R, respectively. Of the pair of traveling pumps 53L and 53R, one traveling pump 53L supplies hydraulic oil to the traveling pump 53L, and the other traveling pump 53R supplies hydraulic oil to the traveling pump 53R.

Hereinafter, for convenience of explanation, the traveling pump 53L is referred to as a left traveling pump 53L, the traveling pump 53R is referred to as a right traveling pump 53R, the traveling motor 36L is referred to as a left traveling motor 36L, and the traveling motor 36R is referred to as a right traveling motor 36R. Sometimes.
The left traveling pump 53L and the right traveling pump 53R have a forward pressure receiving portion 53a and a reverse 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. By changing the angle of the diagonal plate, the output (discharge amount of hydraulic oil) and the discharge direction of the hydraulic oil of the left traveling pump 53L and the right traveling pump 53R can be changed.

The left traveling pump 53L and the left traveling motor 36L are connected by a connecting oil passage 57h, and the 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 the 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 the hydraulic oil discharged from the left traveling pump 53L, and the rotation speed (rotation speed) 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 (rotation speed) of the left traveling motor 36L can be changed by expanding and contracting the swash plate switching cylinder 37L to one side or the other side. it can. 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 extended, the rotation speed of the left traveling motor 36L is set. The number is set to high speed (second speed). That is, the rotation speed of the left traveling motor 36L can be changed between the first speed on the low speed side and the second speed on the high speed side.

The right traveling motor 36R can be rotated by the hydraulic oil discharged from the right traveling pump 53R, and the rotation speed (rotation speed) 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 (rotation speed) of the right traveling motor 36R can be changed by expanding and contracting the swash plate switching cylinder 37R to one side or the other side. it can. 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 extended, the rotation speed of the right traveling motor 36R is set. The number is set to high speed (second speed). That is, the rotation speed of the right traveling motor 36R can be changed between the first speed on the low speed side and the second speed on the high speed side.

As shown in FIG. 1, the hydraulic system of the working machine includes a traveling switching valve 34. The travel switching valve 34 can switch between a first state in which the rotation speed (rotation speed) of the travel motors (left travel motor 36L, right travel motor 36R) is set to the first speed and a second state in which the travel speed is set to the second speed. is there. The traveling switching valve 34 has a first switching valve 71L and 71R and a second switching valve 72.
The first switching valve 71L is a two-position switching valve that is connected to the swash plate switching cylinder 37L of the left traveling motor 36L via an oil passage and switches between the first position 71L1 and the second position 71L2. The first switching valve 71L contracts the swash plate switching cylinder 37L when it is in the first position 71L1, and expands the swash plate switching cylinder 37L when it is in the second position 71L2.

The first switching valve 71R is a two-position switching valve that is connected to the swash plate switching cylinder 37R of the right-handing motor 36R via an oil passage and switches between the first position 71R1 and the second position 71R2. The first switching valve 71R contracts the swash plate switching cylinder 37R at the first position 71R1 and extends the swash plate switching cylinder 37R at the second position 71R2.
The second switching valve 72 is a solenoid valve that switches between the first switching valve 71L and the first switching valve 71R, and is a two-position switching valve that can be switched between the first position 72a and the 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. The second switching valve 72 switches the first switching valve 71L and the first switching valve 71R to the first positions 71L1 and 71R1 when it is in the first position 72a, and switches the first switching valve 71L and 71R when it is in the second position 72b. The first switching valve 71R is switched to the second positions 71L2 and 71R2.

That is, 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 traveling switching valve 34 is in the first state. The rotation speed of the traveling motor (left traveling motor 36L, right traveling 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 traveling switching valve 34 is in the second state and the traveling motor The rotation speed of (left traveling motor 36L, right traveling motor 36R) is set to the second speed.

Therefore, the traveling switching valve 34 can switch the traveling motors (left traveling motor 36L, right traveling motor 36R) between the first speed on the low speed side and the second speed on the high speed side.
The operating device 54 is a device for operating the traveling pump (left traveling pump 53L, right traveling pump 53R), and the angle of the swash plate of the traveling pump (swash plate angle) can be changed. The operating device 54 includes an operating lever 59 and a plurality of operating valves 55.

The operating lever 59 is an operating lever that is supported by the operating valve 55 and swings in the left-right direction (body width direction) or in the front-rear direction. That is, the operating lever 59 can be operated to the right and left from the neutral position N, and can be operated forward and backward from the neutral position N, with reference to the neutral position N. In other words, the operating lever 59 can swing in at least four directions with respect to the neutral position N. For convenience of explanation, the front and rear bidirectional directions, that is, the front-rear direction is referred to as a first direction. Further, the right and left bidirectional directions, that is, the left-right direction (airframe width direction) may be referred to as the second direction.

Further, the plurality of operating valves 55 are operated in common, that is, by one operating lever 59. The plurality of operating valves 55 operate based on the swing of the operating lever 59. Discharge oil passages 40 are connected to the plurality of operation valves 55, and hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied via the discharge oil passages 40. The plurality of operating valves 55 are an operating valve 55A, an operating valve 55B, an operating valve 55C, and an operating valve 55D.

The operation valve 55A is an operation that outputs according to the operation amount (operation) of the previous operation when the operation lever 59 is swung forward (one side) in the front-rear direction (first direction) (when the operation lever 59 is operated forward). The pressure of the oil changes. The operation valve 55B is operated to output according to the operation amount (operation) of the rear operation when the operation lever 59 is swung backward (the other) in the front-rear direction (first direction) (when the operation lever 59 is rear-operated). The pressure of the oil changes. In the left-right direction (second direction), the operation valve 55C outputs when the operation lever 59 swings to the right (one side) (when the operation lever 59 is operated to the right) according to the operation amount (operation) of the right operation. The pressure of the hydraulic oil changes. The operation valve 55D outputs according to the operation amount (operation) of the left operation when the operation lever 59 is swung to the left (the other) in the left-right direction (second direction) (when the operation lever 59 is operated to the left). The pressure of the hydraulic fluid changes.

The plurality of operating valves 55 and the traveling pumps (left traveling pump 53L, right traveling pump 53R) are connected by a traveling oil passage 45. In other words, the traveling pump (left traveling pump 53L, right traveling pump 53R) is a hydraulic device that can be operated by the hydraulic oil output from the operation valve 55 (operation valve 55A, operation valve 55B, operation valve 55C, operation valve 55D). is there.
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 advancing pressure receiving portion 53a of the traveling pump 53L. The second traveling oil passage 45b is an oil passage connected to the reverse pressure receiving portion 53b of the traveling pump 53L. The third traveling oil passage 45c is an oil passage connected to the advancing pressure receiving portion 53a of the traveling pump 53R. The fourth traveling oil passage 45d is an oil passage connected to the reverse pressure receiving portion 53b of the traveling pump 53R. 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.

When the operating lever 59 is swung forward (in the direction of arrow A1 in FIG. 1), the operating valve 55A is operated and the pilot pressure is output from the operating valve 55A. This pilot pressure acts on the pressure receiving portion 53a of the left traveling pump 53L via the first traveling oil passage 45a and acts on the pressure receiving portion 53a of the right traveling pump 53R via the third traveling oil passage 45c. As a result, the angle of the swash plate of the left traveling pump 53L and the right traveling pump 53R is changed, the left traveling motor 36L and the right traveling motor 36R rotate forward (forward rotation), and the work machine 1 moves straight forward.

Further, when the operating lever 59 is swung backward (in the direction of arrow A2 in FIG. 1), the operating valve 55B is operated and the pilot pressure is output from the operating valve 55B. This pilot pressure acts on the pressure receiving portion 53b of the left traveling pump 53L via the second traveling oil passage 45b and acts on the pressure receiving portion 53b of the right traveling pump 53R via the fourth traveling oil passage 45d. As a result, the angle of the swash plate of the left traveling pump 53L and the right traveling pump 53R is changed, the left traveling motor 36L and the right traveling motor 36R are reversed (reverse rotation), and the work machine 1 moves straight backward.

Further, when the operating lever 59 is swung to the right (in the direction of arrow A3 in FIG. 1), the operating valve 55C is operated and the pilot pressure is output from the operating valve 55C. This pilot pressure acts on the pressure receiving portion 53a of the left traveling pump 53L via the first traveling oil passage 45a and acts on the pressure receiving portion 53b of the right traveling pump 53R via the fourth traveling oil passage 45d. As a result, the swash plate angles of the left traveling pump 53L and the right traveling pump 53R are changed, the left traveling motor 36L rotates forward and the right traveling motor 36R reverses, and the work machine 1 turns to the right.

Further, when the operating lever 59 is swung to the left (in the direction of arrow A4 in FIG. 1), the operating valve 55D is operated and the pilot pressure is output from the operating valve 55D. This pilot pressure acts on the pressure receiving portion 53a of the right traveling pump 53R via the third traveling oil passage 45c and acts on the pressure receiving portion 53b of the left traveling pump 53L via the second traveling oil passage 45b. As a result, the swash plate angles of the left traveling pump 53L and the right traveling pump 53R are changed, the left traveling motor 36L reverses, the right traveling motor 36R rotates forward, and the work machine 1 turns to the left.

Further, when the operating lever 59 is swung in an oblique direction, the rotation direction and rotation speed of the left traveling motor 36L and the right traveling 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. , The work machine 1 turns right or left while moving forward or backward.
That is, when the operation lever 59 is swung diagonally forward to the left, the work machine 1 turns left while advancing at a speed corresponding to the swing angle of the operating lever 59, and when the operating lever 59 is swung diagonally forward to the right, the operation lever 59 is swung forward. When the work machine 1 turns to the right while advancing at a speed corresponding to the swing angle of the operation lever 59 and the operation lever 59 is swung diagonally backward to the left, the work machine 1 swings at a speed corresponding to the swing angle of the operation lever 59. When 1 makes a left turn while moving backward and swings the operating lever 59 diagonally rearward to the right, the working machine 1 turns right while moving backward at a speed corresponding to the swing angle of the operating lever 59.

As shown in FIG. 2A, the working machine 1 includes a display device 75. The display device 75 is a device that displays various information about the work machine 1, and is arranged, for example, in front of or to the side of the driver's seat 8.
The display device 75 is composed of a panel or the like for displaying operation information, warning information, and the like. The display device 75 has, for example, a fuel gauge 75a for displaying the remaining amount of fuel, a temperature gauge 75b for displaying the water temperature, and a plurality of warning lights 75c for displaying warning information as operation information. Further, the display device 75 can display the speed (speed of the traveling device) of the pair of traveling motors (left traveling motor 36L, right traveling motor 36R) as operation information, and the speed of the traveling device (rotation of the traveling motor). A display unit 76 capable of displaying that the speed) is the second speed (high speed side) is provided.

The display unit 76 is a lamp such as an LED that can be turned on, off, blinked, and the like. When the rotation speed of the traveling motor) is the second speed, the display unit 76 lights up. Further, when the rotation speed of the traveling motor) is not the second speed but the first speed, the display unit 76 is turned off.
As shown in FIG. 2A, the working machine 1 includes a control device 60. The control device 60 controls the working machine 1 in various ways, and is composed of a CPU, a semiconductor such as an MPU, an electric / electronic circuit, and the like. The accelerator 65, the mode switch 66, the speed changeover switch 67, and the rotation speed detection device 68 are connected to the control device 60. The accelerator 65 is a member for setting the rotation speed (motor rotation speed) of the prime mover 32, and is provided in the vicinity of the driver's seat 8. The accelerator 65 includes an accelerator lever that is swingably supported, an accelerator pedal that is swingably supported, an accelerator volume that is rotatably supported, an accelerator slider that is slidably supported, and the like. The accelerator 65 is not limited to the above-mentioned example.

The mode switch 66 is a switch for switching between enabling and disabling automatic deceleration. For example, the mode switch 66 is a switch that can be switched ON / OFF, and when it is ON, the automatic deceleration is effectively switched, and when it is OFF, the automatic deceleration is disabled.
The speed changeover switch 67 is provided in the vicinity of the driver's seat 8 and can be operated by the driver (operator). The speed changeover switch 67 is a switch capable of manually switching the traveling motor (left traveling motor 36L, right traveling motor 36R) to either the first speed or the second speed. For example, the speed changeover switch 67 is a seesaw switch that switches between the first speed side and the second speed side, and performs a speed increasing operation that switches from the first speed side to the second speed side and changes from the second speed to the first speed. It is possible to perform a deceleration operation to switch.

The rotation speed detection device 68 is composed of a sensor or the like for detecting the rotation speed, and detects the rotation speed of the current prime mover (motor rotation speed). The rotation speed detection device 68 may be a device that detects the rotation speed of the prime mover from the operation amount of the accelerator 65.
As shown in FIGS. 1 and 2, the control device 60 includes an automatic deceleration unit 61. The automatic deceleration unit 61 is a program or the like stored in the control device 60, such as an electric / electronic circuit provided in the control device 60.

The automatic deceleration unit 61 performs automatic deceleration control when automatic deceleration is effective, and does not perform automatic deceleration control when automatic deceleration is invalid.
In the automatic deceleration control, when the traveling motor (left traveling motor 36L, right traveling motor 36R) is at the second speed and a predetermined condition (automatic deceleration condition) is satisfied, the traveling motor (left traveling motor 36L, right traveling) travels to the right. The motor 36R) is automatically switched from the second speed to the first speed. In the automatic deceleration control, at least in a situation where the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed, the control device 60 demagnetizes the solenoid of the second switching valve 72 when the automatic deceleration condition is satisfied. As a result, the traveling motor (left traveling motor 36L, right traveling motor 36R) is decelerated from the second speed to the first speed by switching the second switching valve 72 from the second position 72b to the first position 72a. That is, in the automatic deceleration control, the control device 60 decelerates both the left traveling motor 36L and the right traveling motor 36R from the second speed to the first speed when performing automatic deceleration.

When the return condition is satisfied after the automatic deceleration is performed, the automatic deceleration unit 61 excites the solenoid of the second switching valve 72 to move the second switching valve 72 from the first position 72a to the second position 72b. By switching to, the traveling motor (left traveling motor 36L, right traveling motor 36R) is increased from the first speed to the second speed, that is, the speed of the traveling motor is restored. That is, when returning from the first speed to the second speed, the control device 60 accelerates both the left traveling motor 36L and the right traveling motor 36R from the first speed to the second speed.

When the automatic deceleration is disabled, the control device 60 switches the traveling motor (left traveling motor 36L, right traveling motor 36R) to either the first speed or the second speed according to the operation of the speed changeover switch 67. Performs manual switching control. In the manual switching control, when the speed changeover switch 67 is switched to the first speed side, the solenoid of the second switching valve 72 is degaussed to make the traveling motor (left traveling motor 36L, right traveling motor 36R) first. Make it speed. Further, in the manual switching control, when the speed switching switch 67 is switched to the second speed side, the traveling motor (left traveling motor 36L, right traveling motor 36R) is demagnetized by degaussing the solenoid of the second switching valve 72. Set to the second speed.

By the way, the display device 75 displays that the automatic deceleration is performed when the automatic deceleration (automatic deceleration control) is executed. The display device 75 (display unit 76) displays the automatic deceleration in a display form different from that of the second speed when the automatic deceleration is performed.
FIG. 3 is a flow showing the operation of the control device 60 and the operation of the display device 75.
As shown in FIG. 3, the control device 60 determines whether or not the traveling motor (left traveling motor 36L, right traveling motor 36R) is at the second speed (S1). When the traveling motor is at the second speed (S1, Yes), the display device 75 indicates that it is at the second speed by lighting the display unit 76 (S2). The control device 60 (automatic deceleration unit 61) determines whether or not the automatic deceleration is effective (S3). When the automatic deceleration is effective (S3, Yes), the control device 60 (automatic deceleration unit 61) determines whether or not the automatic deceleration condition is satisfied (S4). When the automatic deceleration condition is satisfied (S4, Yes), the automatic deceleration unit 61 executes automatic deceleration control and decelerates the traveling motor from the second speed to the first speed (S5). The display device 75 indicates that automatic deceleration is being performed by blinking the display unit 76 (S6). For example, the display unit 76 of the display device 75 blinks when the second switching valve 72 switches from the second position 72b to the first position 72a to perform automatic deceleration control. The display unit 76 of the display device 75 is turned off when the first speed is set by the operation of the driver (operator).

On the other hand, when the traveling motors (left traveling motor 36L, right traveling motor 36R) are not at the second speed (S1, No), the control device 60 blinks when the automatic deceleration is performed, and whether or not the automatic deceleration is executed. Is determined (S7). When the automatic deceleration is not executed (S7, No), the display device 75 displays that the speed is the first speed by turning off the display unit 76 (S8).
As described above, the display device 75 (display unit 76) lights up when the automatic deceleration is enabled or disabled in the second speed state (when the automatic deceleration is not performed in the second speed state). Lights up) and flashes when automatic deceleration is performed.

That is, the display device 75 (display unit 76) blinks when the automatic deceleration is performed in the state where the automatic deceleration is enabled by the mode switch 66, and the automatic deceleration is performed in the state of the second speed. Lights when there is none. As a result, the display form of the display unit 76 indicating that the traveling motor is at the second speed is divided into a display form (lighting) when indicating the second speed and a display form (blinking) when indicating automatic deceleration. By performing the above, it is possible to display on one display unit 76 that automatic deceleration is being performed.

In the above-described embodiment, it was shown that the automatic deceleration is performed by blinking the display unit 76 capable of indicating the second speed, but instead, the display is performed as shown in FIG. 2B. A display unit 77 may be provided separately from the unit 76 to indicate that the display unit 77 is performing automatic deceleration. The display unit 77 is, for example, a lamp such as an LED that can be turned on and off. The display unit 77 lights up when automatic deceleration is performed and turns off when automatic deceleration is not performed. The display form of the display unit 77 is not limited, and blinking may indicate that automatic deceleration is performed.

Next, the automatic deceleration condition and the like, which are the conditions under which the automatic deceleration control is executed, will be described.
The control device 60 (automatic deceleration unit 61) sets the pressures of the connecting oil passages 57h and 57i as one of the automatic deceleration conditions.
A traveling pump pressure detecting device 80 that detects the pressures of the connecting oil passages 57h and 57i as the traveling pump pressure V is connected to the control device 60. That is, the traveling pump pressure detecting device 80 uses the pressure of the hydraulic oil (pressure of the connecting oil passages 57h and 57i) discharged by the left traveling pump 53L and the right traveling pump 53R into the connecting oil passages 57h and 57i as the traveling pump pressure V. To detect.

The traveling pump pressure detecting device 80 can detect a plurality of traveling pump pressures of the traveling motor. Specifically, the left traveling motor 36L has a first port P11 and a second port P12, the right traveling motor 36R has a third port P13 and a fourth port P14, and the traveling pump pressure detecting device 80 , The traveling pump pressures of the first port P11 side, the second port P12 side, the third port P13 side, and the fourth port P14 side are detected in the connecting oil passages 57h and 57i. The first port P11 is a port on the discharge side when the left traveling motor 36L rotates normally, and the second port P12 is a port on the suction side when the left traveling motor 36L rotates normally. The third port P13 is a port on the discharge side when the right traveling motor 36R rotates in the normal direction, and the fourth port P14 is a port on the suction side when the right traveling motor 36R rotates in the normal direction.

As shown in FIGS. 1 and 2, the traveling pump pressure detecting device 80 includes a first pressure detecting device 80a, a second pressure detecting device 80b, a third pressure detecting device 80c, and a fourth pressure detecting device 80d.
The first pressure detecting device 80a is provided on the first port P11 side of the left traveling motor 36L in the connecting oil passage 57h, and detects the traveling pump pressure V on the first port P11 side as the first traveling pump pressure V1.

The second pressure detecting device 80b is provided on the second port P12 side of the left traveling motor 36L in the connecting oil passage 57h, and detects the traveling pump pressure V on the second port P12 side as the second traveling pump pressure V2.
The third pressure detecting device 80c is provided on the third port P13 side of the right traveling motor 36R in the connecting oil passage 57i, and detects the traveling pump pressure V on the third port P13 side as the third traveling pump pressure V3.

The fourth pressure detecting device 80d is provided on the fourth port P14 side of the right traveling motor 36R in the connecting oil passage 57i, and detects the traveling pump pressure V on the fourth port P14 side as the fourth traveling pump pressure V4.
In the control device 60, when the traveling pump pressure V (V1 to V4) detected by the traveling pump pressure detecting device 80 is equal to or higher than the first deceleration determination pressure PV1 in a state where one of the pair of traveling motors is at the second speed. In addition, automatic deceleration is performed.

Hereinafter, the determination of automatic deceleration using the traveling pump pressure V (V1 to V4) and the first deceleration determination pressure PV1 will be described in detail.
A first storage device 81a composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a first storage device 81a.
As shown in FIG. 4A, the first deceleration determination pressure PV1 is stored in the first storage device 81a in association with the prime mover rotation speed. That is, the first storage device 81a stores the first deceleration determination table T1 showing the relationship between the prime mover rotation speed and the first deceleration determination pressure PV1. In the first deceleration determination table T1, the first deceleration determination pressure PV1 increases as the prime mover rotation speed increases, and when the prime mover rotation speed is high, the first deceleration determination pressure PV1 is also a high value, and the prime mover rotation. When the number is low, the first deceleration determination pressure PV1 is also a low value.

In the first deceleration determination table T1, for example, when the prime mover rotation speed is 1000 rpm or more and less than 1250 rpm, the first deceleration determination pressure PV1 is 24 MPa, and when the prime mover rotation speed is 1250 rpm or more and less than 1500 rpm, the first deceleration determination is made. When the pressure PV1 is 25 MPa and the prime mover rotation speed is 1500 rpm or more and less than 1750 rpm, the first deceleration judgment pressure PV1 is 26 MPa, and when the prime mover rotation speed is 1750 rpm or more and less than 2000 rpm, the first deceleration judgment pressure PV1 is 27 MPa and the prime mover. When the rotation speed is 2000 rpm or more and less than 2250 rpm, the first deceleration judgment pressure PV1 is 28 MPa, and when the prime mover rotation speed is 2250 rpm or more and less than 2500 rpm, the first deceleration judgment pressure PV1 is 29 MPa and the prime mover rotation speed is 2500 rpm or more. In some cases, it indicates that the first deceleration determination pressure PV1 is 30 MPa. That is, in the first deceleration determination table T1, the numerical value of the prime mover rotation speed indicates a boundary value for setting the first deceleration determination pressure PV1.

The automatic deceleration unit 61 is the first from the prime mover rotation speed detected by the rotation speed detection device 68 and the first deceleration determination table T1 when the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed. 1 The deceleration determination pressure PV1 is extracted. For example, when the prime mover rotation speed is 1300 rpm, the automatic deceleration unit 61 extracts the first deceleration determination pressure PV1 which is 25 MPa from the first deceleration determination table T1, and when the prime mover rotation speed is 2100 rpm, the first deceleration unit 61 is the first. The first deceleration determination pressure PV1 of 28 MPa is extracted from the deceleration determination table T1.

The automatic deceleration unit 61 automatically decelerates when the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 are equal to or higher than the first deceleration determination pressure PV1 extracted from the first deceleration determination table T1. Specifically, in the automatic deceleration unit 61, any one of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the first deceleration determination pressure PV1. In this case, the traveling motor (left traveling motor 36L, right traveling motor 36R) is automatically decelerated from the second speed to the first speed.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 controls to return the traveling motors (left traveling motor 36L, right traveling motor 36R) from the first speed to the second speed when the automatic deceleration is effective. (Return control) is performed.
A second storage device 81b composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a second storage device 81b.

As shown in FIG. 4B, the first return determination pressure QV1 is stored in the second storage device 81b in association with the prime mover rotation speed. That is, the second storage device 81b stores the first return determination table U1 showing the relationship between the prime mover rotation speed and the first return determination pressure QV1. In the first return determination table U1, the first return determination pressure QV1 increases as the prime mover rotation speed increases, and when the prime mover rotation speed is high, the first return determination pressure QV1 is also a high value, and the prime mover rotation When the number is low, the first return determination pressure QV1 is also a low value. In the first return determination table U1, similarly to the first deceleration determination table T1 described above, the numerical value of the prime mover rotation speed indicates a boundary value for setting the first return determination pressure QV1. For example, when the prime mover rotation speed is 1600 rpm, the first return determination pressure QV1 is 16 MPa.

The automatic deceleration unit 61 extracts the first return determination pressure QV1 from the motor rotation speed detected by the rotation speed detection device 68 and the first return determination table U1 after the automatic deceleration, and is detected by the traveling pump pressure detection device 80. When the traveling pump pressures V1 to V4 are equal to or less than the first return determination pressure QV1 extracted from the first return determination table U1, the traveling motors (left traveling motor 36L, right traveling motor 36R) are moved from the first speed to the second. Return to speed. Specifically, the automatic deceleration unit 61 is when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 become equal to or less than the first return determination pressure QV1. , The traveling motor (left traveling motor 36L, right traveling motor 36R) is increased from the first speed to the second speed.

FIG. 5 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 5, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S10, Yes), the automatic deceleration unit 61 has the prime mover rotation speed and the first first speed detected by the rotation speed detection device 68. Refer to the deceleration determination table T1 (S11). The automatic deceleration unit 61 extracts the first deceleration determination pressure PV1 from the first deceleration determination table T1 based on the engine speed (S12). The automatic deceleration unit 61 refers to the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 (S13). The automatic deceleration unit 61 determines whether or not any of the traveling pump pressures V1 to V4 is equal to or higher than the first deceleration determination pressure PV1 (S14).

When any of the traveling pump pressures V1 to V4 is equal to or higher than the first deceleration determination pressure PV1 (S14, Yes), the automatic deceleration unit 61 automatically decelerates (S15).
After performing automatic deceleration, the automatic deceleration unit 61 refers to the prime mover rotation speed and the first return determination table U1 detected by the rotation speed detection device 68 (S16). The automatic deceleration unit 61 extracts the first return determination pressure QV1 from the first return determination table U1 based on the engine speed (S17). The automatic deceleration unit 61 refers to traveling pump pressures V1 to V4 (S18). The automatic deceleration unit 61 determines whether or not all of the traveling pump pressures V1 to V4 are equal to or less than the first return determination pressure QV1 (S19). The automatic deceleration unit 61 performs return control when all of the traveling pump pressures V1 to V4 are equal to or less than the first return determination pressure QV1 (S19, Yes) (S20).

The work machine 1 includes a first storage device 81a and a control device 60 having an automatic deceleration unit 61, and the automatic deceleration unit 61 is detected by the rotation speed detection device 68 when the traveling motor is at the second speed. When the first deceleration determination pressure PV1 is extracted from the motor rotation speed and the first deceleration determination table T1 and the traveling pump pressures V1 to V4 detected by the traveling pump pressure detection device 80 are equal to or higher than the first deceleration determination pressure PV1. In addition, automatic deceleration is performed. According to this, since the automatic deceleration is performed based on the first deceleration determination pressure PV1 according to the rotation speed of the prime mover, the automatic deceleration can be performed at the optimum timing in the operating state of the working machine 1. it can. That is, automatic deceleration can be appropriately performed according to the rotation speed of the prime mover, and work efficiency can be improved.

The work machine 1 includes a second storage device 81b, and the automatic deceleration unit 61 has a first return determination pressure QV1 from the motor rotation speed detected by the rotation speed detection device 68 after automatic deceleration and the first return determination table U1. Is extracted, and when the traveling pump pressures V1 to V4 after automatic deceleration detected by the traveling pump pressure detecting device 80 are equal to or less than the first return determination pressure QV1, the traveling motor is restored from the first speed to the second speed. To do. According to this, since the return is performed based on the first return determination pressure QV1 according to the rotation speed of the prime mover, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1. ..

The automatic deceleration unit 61 is set when any one of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the first deceleration determination pressure PV1. Performs automatic deceleration. According to this, for example, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any case, when a load is applied to the left traveling device 5L or the right traveling device 5R, the vehicle can be appropriately decelerated.

The automatic deceleration unit 61 sets the traveling motor when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 are equal to or less than the first return determination pressure QV1. It returns from the first speed to the second speed. According to this, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any of these cases, the speed can be appropriately increased when the load applied to the left traveling device 5L or the right traveling device 5R is eliminated.

The first storage device 81a stores the first deceleration determination table T1 in which the first deceleration determination pressure PV1 increases as the engine speed increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.
The second storage device 81b stores the first return determination table U1 in which the first return determination pressure QV1 increases as the prime mover rotation speed increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.

In the above-described embodiment, a plurality of traveling pump pressures V1 to V4 are used as automatic deceleration conditions. Instead of this, the differential pressure (traveling difference) between the traveling pump pressures V1 and V3 of the left traveling motor 36L that drives the left traveling device 5L and the traveling pump pressures V2 and V4 of the right traveling motor 36R that drives the right traveling device 5R. The automatic deceleration may be performed based on the pressure). That is, the traveling differential pressure may be a condition for automatic deceleration.

The control device 60 includes a differential pressure calculation unit 63. The differential pressure calculation unit 63 is a program or the like stored in the control device 60, such as an electric / electronic circuit provided in the control device 60. The differential pressure calculation unit 63 includes traveling pump pressures (one-sided traveling pump pressure) V1 and V2 when the left traveling motor 36L is driven among the traveling motor 36L and the right traveling motor 36R, and when the right traveling motor 36R is driven. The traveling difference pressures V5 and V6 with the traveling pump pressure (the other traveling pump pressure) V3 and V4 are calculated.

A third storage device 81c composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a third storage device 81c.
As shown in FIG. 6A, the second deceleration determination pressure PV2 is stored in the third storage device 81c in association with the prime mover rotation speed. That is, the third storage device 81c stores the second deceleration determination table T2 showing the relationship between the prime mover rotation speed and the second deceleration determination pressure PV2. In the second deceleration determination table T2, the second deceleration determination pressure PV2 increases as the prime mover rotation speed increases, and when the prime mover rotation speed is high, the second deceleration determination pressure PV2 is also a high value, and the prime mover rotation When the number is low, the second deceleration determination pressure PV2 is also a low value.

In the second deceleration determination table T2, similarly to the first deceleration determination table T1 described above, the numerical value of the prime mover rotation speed indicates a boundary value for setting the second deceleration determination pressure PV2. For example, when the prime mover rotation speed is 1600 rpm, the second deceleration determination pressure PV2 is 16 MPa.
The differential pressure calculation unit 63 calculates the first differential pressure, which is the difference between the first traveling pump pressure V1 and the third traveling pump pressure V3, as the traveling differential pressure V5, and calculates the second traveling pump pressure V2 and the fourth traveling pump pressure. The second differential pressure, which is the difference from V4, is calculated as the running differential pressure V6.

When the traveling motor (left traveling motor 36L, right traveling motor 36R) is at the second speed, the automatic deceleration unit 61 is the second from the prime mover rotation speed detected by the rotation speed detection device 68 and the second deceleration determination table T2. 2 The deceleration determination pressure PV2 is extracted.
The automatic deceleration unit 61 automatically decelerates when the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 are equal to or higher than the second deceleration determination pressure PV2 extracted from the second deceleration determination table T2. Specifically, the automatic deceleration unit 61 automatically decelerates when either the first differential pressure (V5) or the second differential pressure (V6) is equal to or higher than the second deceleration determination pressure PV2.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 performs a return control when the automatic deceleration is effective.
A fourth storage device 81d composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a fourth storage device 81d.
As shown in FIG. 6B, the second return determination pressure QV2 is stored in the fourth storage device 81d in association with the prime mover rotation speed. That is, the fourth storage device 81d stores the second return determination table U2 showing the relationship between the prime mover rotation speed and the second return determination pressure QV2. In the second return determination table U2, the second return determination pressure QV2 increases as the prime mover rotation speed increases, and when the prime mover rotation speed is high, the second return determination pressure QV2 is also a high value, and the prime mover rotation When the number is low, the second return determination pressure QV2 is also a low value. In the second return determination table U2, as in the second deceleration determination table T2 described above, the numerical value of the prime mover rotation speed indicates a boundary value for setting the second return determination pressure QV2. For example, when the prime mover rotation speed is 1600 rpm, the second return determination pressure QV2 is 17 MPa.

The automatic deceleration unit 61 extracts the second return determination pressure QV2 from the prime mover rotation speed detected by the rotation speed detection device 68 and the second return determination table U2 after the automatic deceleration, and the traveling is calculated by the differential pressure calculation unit 63. When the differential pressures V5 and V6 are equal to or less than the second return determination pressure QV2 extracted from the second return determination table U2, the return control is executed. Specifically, the automatic deceleration unit 61 accelerates the traveling motor from the first speed to the second speed when the traveling differential pressures V5 and V6 become equal to or less than the second return determination pressure QV2.

FIG. 7 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 7, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S30, Yes), the automatic deceleration unit 61 has the prime mover rotation speed and the second speed detected by the rotation speed detection device 68. Refer to the deceleration determination table T2 (S31). The automatic deceleration unit 61 extracts the second deceleration determination pressure PV2 from the second deceleration determination table T2 based on the engine speed (S32). The differential pressure calculation unit 63 calculates the first differential pressure (V5) and the second differential pressure (V6) from the traveling pump pressures V1 to V4 (S33). The automatic deceleration unit 61 determines whether or not any of the first differential pressure (V5) and the second differential pressure (V6) is equal to or higher than the second deceleration determination pressure PV2 (S34). When either the first differential pressure (V5) or the second differential pressure (V6) is equal to or higher than the second deceleration determination pressure PV2 (S34, Yes), the automatic deceleration unit 61 automatically decelerates (S35).

After performing automatic deceleration, the automatic deceleration unit 61 refers to the prime mover rotation speed and the second return determination table U2 detected by the rotation speed detection device 68 (S36). The automatic deceleration unit 61 extracts the second return determination pressure QV2 from the second return determination table U2 based on the engine speed (S37). The automatic deceleration unit 61 refers to the first differential pressure (V5) and the second differential pressure (V6) after the automatic deceleration (S38).

The automatic deceleration unit 61 determines whether or not the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the second return determination pressure QV2 (S39). When the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the second return determination pressure QV2 (S39, Yes), the automatic deceleration unit 61 performs return control (S40).
The work machine 1 includes a third storage device 81c, a control device 60 having an automatic deceleration unit 61 and a differential pressure calculation unit 63, and the automatic deceleration unit 61 detects the number of revolutions when the traveling motor is at the second speed. The second deceleration determination pressure PV2 is extracted from the motor rotation speed detected by the device 68 and the second deceleration determination table T2, and any of the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 is the second. When the deceleration determination pressure is PV2 or higher, automatic deceleration is performed. According to this, since automatic deceleration is performed based on the second deceleration determination pressure PV2 according to the rotation speed of the prime mover, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1. it can. In particular, automatic deceleration can be efficiently performed when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The work machine 1 includes a fourth storage device 81d, and the automatic deceleration unit 61 has a second return determination pressure QV2 from the motor rotation speed detected by the rotation speed detection device 68 after the automatic deceleration and the second return determination table U2. Is extracted, and when both the traveling differential pressures V5 and V6 after automatic deceleration calculated by the differential pressure calculation unit 63 are equal to or less than the second return determination pressure QV2, the traveling motor is changed from the first speed to the second speed. Return. According to this, since the return is performed based on the second return determination pressure QV2 according to the rotation speed of the prime mover, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1. .. In particular, it is possible to efficiently recover after performing automatic deceleration when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The differential pressure calculation unit 63 uses the first differential pressure (V5), which is the difference between the first traveling pump pressure V1 and the third traveling pump pressure V3, and the second traveling pump pressure V2 and the fourth traveling as the traveling differential pressure. The second differential pressure (V6), which is the difference from the pump pressure V4, is obtained, and the automatic deceleration unit 61 determines that either the first differential pressure (V5) or the second differential pressure (V6) is the second deceleration determination pressure PV2. If the above is the case, automatic deceleration is performed. According to this, automatic deceleration can be efficiently performed in either the situation where the work machine 1 is moving forward or backward.

When both the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the second return determination pressure QV2, the automatic deceleration unit 61 sets at least one of the traveling motors from the first speed to the second. Return to speed. According to this, it is possible to efficiently return the work machine 1 in either the forward or reverse situation.
The third storage device 81c stores the second deceleration determination table T2 in which the second deceleration determination pressure PV2 increases as the engine speed increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.

The fourth storage device 81d stores the second return determination table U2 in which the second return determination pressure QV2 increases as the prime mover rotation speed increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.
In the above-described embodiment, automatic deceleration is performed based on a plurality of traveling pump pressures V1 to V4 corresponding to the motor rotation speed, but it corresponds to the swash plate angle of the traveling pumps (left traveling pump 53L, right traveling pump 53R). Automatic deceleration may be performed based on a plurality of traveling pump pressures V1 to V4.

The swash plate angle detecting device 69 and the fifth storage device 81e are connected to the control device 60. The swash plate angle detection device 69 is a device that detects the swash plate angle of the traveling pumps (left traveling pump 53L, right traveling pump 53R). The swash plate angle detection device 69 is, for example, a traveling pump (left traveling pump 53L) even if it is a sensor that detects the pressure (pilot pressure) of the hydraulic oil in the traveling oil passage 45 and converts the pilot pressure into the swash plate angle. , Right traveling pump 53R) Even if it is a sensor that detects the operation amount of the regulator and detects the angle of the sloping plate, or if it is a variable resistor or potentiometer obtained from the operation amount of the operation lever 59, other sensors etc. There is no limitation. In this embodiment, the swash plate angle detecting device 69 determines the swash plate angle of the traveling pump by detecting the pressure (pilot pressure) of the hydraulic oil in the traveling oil passage 45. Therefore, in FIGS. 8A and 8B, etc. The swash plate angle is indicated by the pilot pressure corresponding to the swash plate angle.

The fifth storage device 81e is a non-volatile memory or the like.
As shown in FIG. 8A, the third deceleration determination pressure PV3 is stored in the fifth storage device 81e in association with the swash plate angle. That is, the fifth storage device 81e stores the third deceleration determination table T3 showing the relationship between the swash plate angle (pilot pressure corresponding to the swash plate angle) and the third deceleration determination pressure PV3. In the third deceleration determination table T3, the third deceleration determination pressure PV3 increases as the swash plate angle increases, and when the swash plate angle is high, the third deceleration determination pressure PV3 is also a high value. When the angle is low, the third deceleration determination pressure PV3 is also a low value. In the third deceleration determination table T3, similarly to the first deceleration determination table T1 and the like described above, the numerical value of the swash plate angle indicates a boundary value for setting the third deceleration determination pressure PV3. For example, when the pilot pressure corresponding to the swash plate angle is 0.8 MPa, the third deceleration determination pressure PV3 is 26 MPa.

The automatic deceleration unit 61 is based on the swash plate angle detected by the swash plate angle detection device 69 and the third deceleration determination table T3 when the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed. The third deceleration determination pressure PV3 is extracted. For example, when the pilot pressure corresponding to the tilt plate angle is 0.160 MPa, the automatic deceleration unit 61 extracts the third deceleration determination pressure PV3 of 28 MPa from the third deceleration determination table T3 and corresponds to the tilt plate angle. When the pilot pressure to be applied is 0.11 MPa, the third deceleration determination pressure PV3 of 26 MPa is extracted from the third deceleration determination table T3.

The automatic deceleration unit 61 automatically decelerates when any of the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 is equal to or higher than the third deceleration determination pressure PV3 extracted from the third deceleration determination table T3. I do. Specifically, in the automatic deceleration unit 61, any one of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the third deceleration determination pressure PV3. In this case, the traveling motor (left traveling motor 36L, right traveling motor 36R) is automatically decelerated from the second speed to the first speed.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 controls to return the traveling motors (left traveling motor 36L, right traveling motor 36R) from the first speed to the second speed when the automatic deceleration is effective. (Return control) is performed.
A sixth storage device 81f composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a sixth storage device 81f.

As shown in FIG. 8B, the third return determination pressure QV3 is stored in the sixth storage device 81f in association with the swash plate angle. That is, the sixth storage device 81f stores the third return determination table U3 showing the relationship between the swash plate angle and the third return determination pressure QV3. In the third return determination table U3, the third return determination pressure QV3 increases as the swash plate angle increases, and when the swash plate angle is high, the third return determination pressure QV3 is also a high value, and the swash plate When the angle is low, the third return determination pressure QV3 is also a low value. In the third return determination table U3, similarly to the third deceleration determination table T3 described above, the numerical value of the swash plate angle indicates a boundary value for setting the third return determination pressure QV3. For example, when the pilot pressure corresponding to the swash plate angle is 0.8 MPa, the third return determination pressure QV3 is 16 MPa.

The automatic deceleration unit 61 extracts the third return determination pressure QV3 from the swash plate angle detected by the swash plate angle detection device 69 and the third return determination table U3 after the automatic deceleration, and detects it by the traveling pump pressure detection device 80. When the traveling pump pressures V1 to V4 are equal to or less than the third return determination pressure QV3 extracted from the third return determination table U3, the traveling motors (left traveling motor 36L, right traveling motor 36R) are changed from the first speed. Return to 2 speed. Specifically, the automatic deceleration unit 61 is when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 become equal to or less than the third return determination pressure QV3. , The traveling motor (left traveling motor 36L, right traveling motor 36R) is increased from the first speed to the second speed.

FIG. 9 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 9, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S50, Yes), the automatic deceleration unit 61 has the swash plate angle and the second speed detected by the swash plate angle detection device 69. 3 Refer to the deceleration determination table T3 (S51). In addition, in determining the automatic deceleration, the automatic deceleration unit 61 adopts the swash plate angle when the traveling pumps (left traveling pump 53L, right traveling pump 53R) are driven to the forward side in the case of forward rotation. However, in the case of reverse rotation, the swash plate angle when the traveling pump (left traveling pump 53L, right traveling pump 53R) is driven to the reverse side is adopted. Further, the swash plate angle of the left traveling pump 53L and the right traveling pump 53R is detected regardless of whether the traveling pumps (left traveling pump 53L, right traveling pump 53R) are driven to the forward side or the reverse side. It is possible. In this case, the automatic deceleration unit 61 uses, for example, a value obtained by averaging the swash plate angle of the left traveling pump 53L and the swash plate angle of the right traveling pump 53R as a determination value for automatic deceleration or the like.

The automatic deceleration unit 61 extracts the third deceleration determination pressure PV3 from the third deceleration determination table T3 based on the swash plate angle (S52). The automatic deceleration unit 61 refers to the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 (S53). The automatic deceleration unit 61 determines whether or not any of the traveling pump pressures V1 to V4 is equal to or higher than the third deceleration determination pressure PV3 (S54).
When any of the traveling pump pressures V1 to V4 is equal to or higher than the third deceleration determination pressure PV3 (S54, Yes), the automatic deceleration unit 61 automatically decelerates (S55).

After performing automatic deceleration, the automatic deceleration unit 61 refers to the swash plate angle detected by the swash plate angle detection device 69 and the third return determination table U3 (S56). The automatic deceleration unit 61 extracts the third return determination pressure QV3 from the third return determination table U3 based on the swash plate angle (S57). The automatic deceleration unit 61 refers to the traveling pump pressures V1 to V4 (S58). The automatic deceleration unit 61 determines whether or not the traveling pump pressures V1 to V4 are equal to or less than the third return determination pressure QV3 (S59). When all of the traveling pump pressures V1 to V4 are equal to or less than the third return determination pressure QV3 (S59, Yes), the automatic deceleration unit 61 performs return control (S60).

The work machine 1 includes a swash plate angle detection device 69, a fifth storage device 81e, and a control device 60 having an automatic deceleration unit 61, and the automatic deceleration unit 61 is used when the traveling motor is at the second speed. The third deceleration determination pressure PV3 is extracted from the swash plate angle detected by the swash plate angle detection device 69 and the third deceleration determination table T3, and any of the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80. When the third deceleration determination pressure PV3 or more is achieved, automatic deceleration is performed. According to this, since automatic deceleration is performed based on the third deceleration determination pressure PV3 according to the swash plate angle of the traveling pumps (left traveling pump 53L, right traveling pump 53R), the working machine 1 is in the operating state. Automatic deceleration can be performed at the optimum timing. That is, automatic deceleration can be appropriately performed according to the rotation speed of the prime mover, and work efficiency can be improved.

The work machine 1 includes a sixth storage device 81f that stores a third return determination table U3 showing the relationship between the swash plate angle and the third return determination pressure QV3, and the automatic deceleration unit 61 includes the swash plate angle after automatic deceleration. The third return determination pressure QV3 is extracted from the swash plate angle detected by the detection device 69 and the third return determination table U3, and the traveling pump pressures V1 to V4 after automatic deceleration are equal to or less than the third return determination pressure QV3. In this case, the traveling motor is returned from the first speed to the second speed. According to this, since the return is performed based on the third return determination pressure QV3 according to the swash plate angle of the traveling pump, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1. ..

When any of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the third deceleration determination pressure PV3, the automatic deceleration unit 61 is used. Performs automatic deceleration. According to this, for example, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any case, when a load is applied to the left traveling device 5L or the right traveling device 5R, the vehicle can be appropriately decelerated.

The automatic deceleration unit 61 sets the traveling motor when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 are equal to or less than the third return determination pressure QV3. It returns from the first speed to the second speed. According to this, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any of these cases, the speed can be appropriately increased when the load applied to the left traveling device 5L or the right traveling device 5R is eliminated.

The fifth storage device 81e stores the third deceleration determination table T3 in which the third deceleration determination pressure PV3 increases as the swash plate angle increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.
The sixth storage device 81f stores the third return determination table U3 in which the third return determination pressure QV3 increases as the swash plate angle increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.

In the above-described embodiment, a plurality of traveling pump pressures V1 to V4 corresponding to the swash plate angle are used as the automatic deceleration condition. Instead of this, automatic deceleration may be performed based on the traveling differential pressures V5 and V6 corresponding to the swash plate angle.
A seventh storage device 81 g composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a seventh storage device 81 g.

As shown in FIG. 10A, the fourth deceleration determination pressure PV4 is stored in the seventh storage device 81g in association with the swash plate angle. That is, the seventh storage device 81g stores the fourth deceleration determination table T4 showing the relationship between the swash plate angle and the fourth deceleration determination pressure PV4. In the fourth deceleration determination table T4, the fourth deceleration determination pressure PV4 increases as the swash plate angle increases, and when the swash plate angle is high, the fourth deceleration determination pressure PV4 is also a high value. When the angle is low, the fourth deceleration determination pressure PV4 is also a low value.

In the fourth deceleration determination table T4, similarly to the first deceleration determination table T1 described above, the numerical value of the swash plate angle indicates a boundary value for setting the fourth deceleration determination pressure PV4. For example, when it is 0.8 MPa corresponding to the swash plate angle, the fourth deceleration determination pressure PV4 is 21 MPa.
In the situation where the working machine 1 is moving forward, the differential pressure calculation unit 63 calculates the first differential pressure (V5), which is the difference between the first traveling pump pressure V1 and the third traveling pump pressure V3. Further, in the situation where the working machine 1 is moving backward, the differential pressure calculation unit 63 calculates the second differential pressure (V6).

The automatic deceleration unit 61 is based on the swash plate angle detected by the swash plate angle detection device 69 and the fourth deceleration determination table T4 when the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed. The fourth deceleration determination pressure PV4 is extracted.
The automatic deceleration unit 61 automatically decelerates when the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 are equal to or higher than the fourth deceleration determination pressure PV4 extracted from the fourth deceleration determination table T4. Specifically, the automatic deceleration unit 61 automatically decelerates when either the first differential pressure (V5) or the second differential pressure (V6) is equal to or higher than the fourth deceleration determination pressure PV4.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 performs a return control when the automatic deceleration is effective.
An eighth storage device 81h composed of a non-volatile memory or the like is connected to the control device 60. The 8th storage device 81h may be built in the control device 60.
As shown in FIG. 10B, the fourth return determination pressure QV4 is stored in the eighth storage device 81h in association with the swash plate angle. That is, the eighth storage device 81h stores the fourth return determination table U4 showing the relationship between the swash plate angle and the fourth return determination pressure QV4. In the fourth return determination table U4, the fourth return determination pressure QV4 increases as the swash plate angle increases, and when the swash plate angle is high, the fourth return determination pressure QV4 is also a high value, and the swash plate When the angle is low, the fourth return determination pressure QV4 is also a low value. In the fourth return determination table U4, similarly to the fourth deceleration determination table T4 described above, the numerical value of the swash plate angle indicates a boundary value for setting the fourth return determination pressure QV4. For example, when the pilot pressure corresponding to the swash plate angle is 0.8 MPa, the fourth return determination pressure QV4 is 16 MPa.

The automatic deceleration unit 61 extracted the fourth return determination pressure QV4 from the swash plate angle detected by the swash plate angle detection device 69 and the fourth return determination table U4 after the automatic deceleration, and the differential pressure calculation unit 63 calculated. When the traveling differential pressures V5 and V6 are equal to or less than the fourth return determination pressure QV4 extracted from the fourth return determination table U4, the return control is executed. Specifically, the automatic deceleration unit 61 accelerates the traveling motor from the first speed to the second speed when the traveling differential pressures V5 and V6 become equal to or less than the fourth return determination pressure QV4.

FIG. 11 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 11, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S70, Yes), the automatic deceleration unit 61 has the swash plate angle and the second speed detected by the swash plate angle detection device 69. 4 Refer to the deceleration determination table T4 (S71). The automatic deceleration unit 61 extracts the fourth deceleration determination pressure PV4 from the fourth deceleration determination table T4 based on the swash plate angle (S72). The differential pressure calculation unit 63 calculates the first differential pressure (V5) and the second differential pressure (V6) from the traveling pump pressures V1 to V4 (S73). The automatic deceleration unit 61 determines whether or not the first differential pressure (V5) and the second differential pressure (V6) are equal to or higher than the fourth deceleration determination pressure PV4 (S74). The automatic deceleration unit 61 automatically decelerates when the first differential pressure (V5) and the second differential pressure (V6) are equal to or higher than the fourth deceleration determination pressure PV4 (S74, Yes) (S75).

After performing automatic deceleration, the automatic deceleration unit 61 refers to the swash plate angle detected by the swash plate angle detection device 69 and the fourth return determination table U4 (S76). The automatic deceleration unit 61 extracts the fourth return determination pressure QV4 from the fourth return determination table U4 based on the swash plate angle (S77). The automatic deceleration unit 61 refers to the first differential pressure (V5) and the second differential pressure (V6) after the automatic deceleration (S78).

The automatic deceleration unit 61 determines whether or not the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the fourth return determination pressure QV4 (S79). When the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the fourth return determination pressure QV4 (S79, Yes), the automatic deceleration unit 61 performs return control (S80).
The work machine 1 includes a swash plate angle detection device 69, a seventh storage device 81 g, and a control device 60 having an automatic deceleration unit 61 and a differential pressure calculation unit 63. The automatic deceleration unit 61 has a traveling motor. In the case of two speeds, the fourth deceleration determination pressure PV4 is extracted from the swash plate angle detected by the swash plate angle detection device 69 and the fourth deceleration determination table T4, and the running difference calculated by the differential pressure calculation unit 63. When any of the pressures V5 and V6 is equal to or higher than the fourth deceleration determination pressure PV4, automatic deceleration is performed. According to this, since automatic deceleration is performed based on the fourth deceleration determination pressure PV4 according to the swash plate angle of the traveling pump, it is possible to switch to the high speed side at the optimum timing in the operating state of the work equipment 1. it can. In particular, automatic deceleration can be efficiently performed when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The work machine 1 includes an eighth storage device 81h, and the automatic deceleration unit 61 sets a fourth return determination pressure from the oblique plate angle detected by the oblique plate angle detection device 69 and the fourth return determination table U4 after automatic deceleration. QV4 is extracted, and when both the traveling differential pressures V5 and V6 after automatic deceleration are equal to or less than the fourth return determination pressure QV4, the traveling motor is restored from the first speed to the second speed. According to this, since the return is performed based on the fourth return determination pressure QV4 according to the swash plate angle of the traveling pump, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1. .. In particular, automatic deceleration can be efficiently performed when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The automatic deceleration unit 61 automatically decelerates when either the first differential pressure (V5) or the second differential pressure (V6) is equal to or higher than the fourth deceleration determination pressure PV4. According to this, automatic deceleration can be efficiently performed in either the situation where the work machine 1 is moving forward or backward.
The automatic deceleration unit 61 returns the traveling motor from the first speed to the second speed when both the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the fourth return determination pressure QV4. According to this, it is possible to efficiently return the work machine 1 in either the forward or backward situation.

The seventh storage device 81g stores the fourth deceleration determination table T4 in which the fourth deceleration determination pressure PV4 increases as the swash plate angle increases. In the work machine 1, work with a large workload can be efficiently performed.
The eighth storage device 81h stores the fourth return determination table U4 in which the fourth return determination pressure QV4 increases as the swash plate angle increases. In the work machine 1, work with a large workload can be efficiently performed.

In the above-described embodiment, automatic deceleration is performed based on a plurality of traveling pump pressures V1 to V4 corresponding to the prime mover rotation speed or a plurality of traveling pump pressures V1 to V4 corresponding to the swash plate angle, but anti-stall. Automatic deceleration may be performed by a plurality of traveling pump pressures V1 to V4 corresponding to the pressure of the valve 58.
As shown in FIG. 12, an anti-stall valve 58 is provided in the middle of the discharge oil passage 40. The anti-stall valve 58 is provided on the primary side of the operation valve 55 (operation valve 55A, operation valve 55B, operation valve 55C, operation valve 55D) and is a valve that controls the hydraulic oil supplied to the operation valve 55.

The anti-stall valve 58 controls to prevent engine stall (anti-stall control). FIG. 13 shows the relationship between the engine speed, the secondary pilot pressure of the anti-stall valve 58, and the control lines L1 and L2. The secondary pilot pressure is the pressure (secondary pressure) of the hydraulic oil actuated by the anti-stall valve 58, and in the discharge oil passage 40, the anti-stall valve 58 to the operation valve 55 (operation valve 55a, operation valve 55b, It is the pressure (pilot pressure) of the hydraulic oil in the section leading to the operation valve 55c and the operation valve 55d). That is, it is the primary pressure of the hydraulic oil that enters the operating valve 55 provided on the operating lever 59. The control line L1 shows the relationship between the engine speed and the secondary pilot pressure when the drop amount is less than a predetermined value. The control line L2 shows the relationship between the engine speed and the secondary pilot pressure when the drop amount is equal to or greater than a predetermined value.

When the drop amount is less than a predetermined value, the control device 60 adjusts the opening degree of the anti-stall valve 58 so that the relationship between the actual rotation speed of the prime mover and the secondary pilot pressure matches the control line L1. Further, when the drop amount is equal to or larger than a predetermined value, the control device 60 adjusts the opening degree of the anti-stall valve 58 so that the relationship between the actual rotation speed of the prime mover and the secondary pilot pressure matches the control line L2. .. On the control line L2, the secondary pilot pressure with respect to the predetermined engine speed is lower than the secondary pilot pressure on the control line L1. That is, when focusing on the same prime mover rotation speed, the secondary pilot pressure of the control line L2 is lower than the secondary pilot pressure of the control line L1. Therefore, the pressure (pilot pressure) of the hydraulic oil entering the operation valve 55 can be suppressed low by the control based on the control line L2. As a result, the swash plate angle of the traveling pumps (left traveling pump 53L, right traveling pump 53R) is adjusted, the load acting on the prime mover is reduced, and the stall of the prime mover can be prevented. Although one control line L2 is shown in FIG. 13, there may be a plurality of control lines L2. For example, the control line L2 may be set for each prime mover rotation speed. Further, it is preferable that the control device 60 has data indicating the control line L1 and the control line L2, control parameters such as a function, and the like.

A first storage device 81a composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include the ninth storage device 81i.
As shown in FIG. 14A, the fifth deceleration determination pressure PV5 is stored in association with the secondary pilot pressure in the ninth storage device 81i. That is, the ninth storage device 81i stores the fifth deceleration determination table T5 showing the relationship between the secondary pilot pressure and the fifth deceleration determination pressure PV5. In the fifth deceleration determination table T5, the fifth deceleration determination pressure PV5 increases as the secondary pilot pressure increases, and when the secondary pilot pressure is high, the fifth deceleration determination pressure PV5 is also a high value. When the secondary pilot pressure is low, the fifth deceleration determination pressure PV5 is also a low value. In the fifth deceleration determination table T5, the numerical value of the secondary pilot pressure indicates the boundary value for setting the fifth deceleration determination pressure PV5, as in the above-described embodiment. For example, when the secondary pilot pressure is 1.3 MPa, the fifth deceleration determination pressure PV5 is 25 MPa. The secondary pilot pressure of the anti-stall valve 58 is determined by the control value (for example, current) when the control device 60 controls the anti-stall valve 58 and the flow rate of the hydraulic oil discharged from the first hydraulic pump P1. Can be done. Further, a pressure detecting device for detecting the pressure may be provided on the downstream side of the anti-stall valve 58 to detect the secondary pilot pressure, and the method for detecting the secondary pilot pressure is not limited. Hereinafter, the description will proceed assuming that the secondary pilot pressure is detected by the control device 60 or the pressure detection device.

The automatic deceleration unit 61 extracts the fifth deceleration determination pressure PV5 from the secondary pilot pressure and the fifth deceleration determination table T5 when the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed. .. For example, when the secondary pilot pressure is 2.1 MPa, the automatic deceleration unit 61 extracts the fifth deceleration determination pressure PV5, which is 28 MPa, from the fifth deceleration determination table T5, and the secondary pilot pressure is 1.6 MPa. If there is, the fifth deceleration determination pressure PV5, which is 26 MPa, is extracted from the fifth deceleration determination table T5.

The automatic deceleration unit 61 automatically decelerates when any of the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 is equal to or higher than the fifth deceleration determination pressure PV5 extracted from the fifth deceleration determination table T5. I do. Specifically, in the automatic deceleration unit 61, any one of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the fifth deceleration determination pressure PV5. In this case, the traveling motor (left traveling motor 36L, right traveling motor 36R) is automatically decelerated from the second speed to the first speed.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 controls to return the traveling motors (left traveling motor 36L, right traveling motor 36R) from the first speed to the second speed when the automatic deceleration is effective. (Return control) is performed.
A tenth storage device 81j composed of a non-volatile memory or the like is connected to the control device 60. The control device 60 may include a tenth storage device 81j.

As shown in FIG. 14B, the fifth return determination pressure QV5 is stored in the tenth storage device 81j in association with the secondary pilot pressure. That is, the tenth storage device 81j stores the fifth return determination table U5 showing the relationship between the secondary pilot pressure and the fifth return determination pressure QV5. In the fifth return determination table U5, the fifth return determination pressure QV5 increases as the secondary pilot pressure increases, and when the secondary pilot pressure is high, the fifth return determination pressure QV5 is also a high value. When the secondary pilot pressure is low, the fifth return determination pressure QV5 is also a low value. In the fifth return determination table U5, as in the fifth deceleration determination table T5 described above, the numerical value of the secondary pilot pressure indicates a boundary value for setting the fifth return determination pressure QV5. For example, when the secondary pilot pressure is 1.6 MPa, the fifth return determination pressure QV5 is 16 MPa.

After the automatic deceleration, the automatic deceleration unit 61 extracts the fifth return determination pressure QV5 from the secondary pilot pressure and the fifth return determination table U5, and the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 When the fifth return determination pressure QV5 or less extracted from the fifth return determination table U5 or less, the traveling motors (left traveling motor 36L, right traveling motor 36R) are restored from the first speed to the second speed. Specifically, the automatic deceleration unit 61 is at a time when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 become the fifth return determination pressure QV5 or less. , The traveling motor (left traveling motor 36L, right traveling motor 36R) is increased from the first speed to the second speed.

FIG. 15 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 15, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S90, Yes), the automatic deceleration unit 61 refers to the secondary pilot pressure and the fifth deceleration determination table T5 (S90, Yes). S91). The automatic deceleration unit 61 extracts the fifth deceleration determination pressure PV5 from the fifth deceleration determination table T5 based on the secondary pilot pressure (S92). The automatic deceleration unit 61 refers to the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 (S93). The automatic deceleration unit 61 determines whether or not any of the traveling pump pressures V1 to V4 is equal to or higher than the fifth deceleration determination pressure PV5 (S94).

When any of the traveling pump pressures V1 to V4 is equal to or higher than the fifth deceleration determination pressure PV5 (S94, Yes), the automatic deceleration unit 61 automatically decelerates (S95).
After performing automatic deceleration, the automatic deceleration unit 61 refers to the secondary pilot pressure and the fifth return determination table U5 (S96). The automatic deceleration unit 61 extracts the fifth return determination pressure QV5 from the fifth return determination table U5 based on the secondary pilot pressure (S97). The automatic deceleration unit 61 refers to traveling pump pressures V1 to V4 (S98). The automatic deceleration unit 61 determines whether or not all of the traveling pump pressures V1 to V4 are equal to or less than the fifth return determination pressure QV5 (S99). When all of the traveling pump pressures V1 to V4 are equal to or less than the fifth return determination pressure QV5 (S99, Yes), the automatic deceleration unit 61 performs return control (S100).

The work machine 1 includes an anti-stall valve 58, a ninth storage device 81i, and a control device 60 having an automatic deceleration unit 61. The automatic deceleration unit 61 is a secondary pilot when the traveling motor is at the second speed. The fifth deceleration determination pressure PV5 is extracted from the pressure and the fifth deceleration determination table T5, and any of the traveling pump pressures V1 to V4 detected by the traveling pump pressure detecting device 80 is equal to or higher than the fifth deceleration determination pressure PV5. In some cases, automatic deceleration is performed. According to this, since automatic deceleration is performed based on the fifth deceleration determination pressure PV5 according to the secondary pilot pressure of the anti-stall valve 58, automatic deceleration is performed at the optimum timing in the operating state of the work equipment 1. It can be carried out. That is, automatic deceleration can be appropriately performed according to the rotation speed of the prime mover, and work efficiency can be improved.

The work machine 1 includes a tenth storage device 81j, and the automatic deceleration unit 61 extracts the fifth return determination pressure QV5 from the secondary pilot pressure and the fifth return determination table U5 after the automatic deceleration, and detects the traveling pump pressure. When the traveling pump pressures V1 to V4 after automatic deceleration detected by the device 80 are equal to or less than the fifth return determination pressure QV5, the traveling motor is restored from the first speed to the second speed. According to this, since the return is performed based on the fifth return determination pressure QV5 according to the secondary pilot pressure, it is possible to switch to the high speed side at the optimum timing in the operating state of the work machine 1.

The automatic deceleration unit 61 is set when any one of the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 is equal to or higher than the fifth deceleration determination pressure PV5. Performs automatic deceleration. According to this, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any of these cases, the speed can be appropriately increased when the load applied to the left traveling device 5L or the right traveling device 5R is eliminated.

The automatic deceleration unit 61 sets the traveling motor when the first traveling pump pressure V1, the second traveling pump pressure V2, the third traveling pump pressure V3, and the fourth traveling pump pressure V4 are equal to or less than the fifth return determination pressure QV5. It returns from the first speed to the second speed. According to this, when the left traveling device 5L operates on the forward side, when the left traveling device 5L operates on the reverse side, when the right traveling device 5R operates on the forward side, the right traveling device 5R operates on the reverse side. In any of these cases, the speed can be appropriately increased when the load applied to the left traveling device 5L or the right traveling device 5R is eliminated.

The first storage device 81a stores the fifth deceleration determination table T5 in which the fifth deceleration determination pressure PV5 increases as the secondary pilot pressure increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.
The second storage device 81b stores the fifth return determination table U5 in which the fifth return determination pressure QV5 increases as the secondary pilot pressure increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.

In the above-described embodiment, a plurality of traveling pump pressures V1 to V4 corresponding to the secondary pilot pressure are used. Instead of this, automatic deceleration may be performed based on the traveling differential pressures V5 and V6 corresponding to the secondary pilot pressure.
An eleventh storage device 81k composed of a non-volatile memory or the like is connected to the control device 60. The 11th storage device 81k may be built in the control device 60.

As shown in FIG. 16A, the sixth deceleration determination pressure PV6 is stored in the eleventh storage device 81k in association with the secondary pilot pressure. That is, the eleventh storage device 81k stores the sixth deceleration determination table T6 showing the relationship between the secondary pilot pressure and the sixth deceleration determination pressure PV6. In the sixth deceleration determination table T6, the sixth deceleration determination pressure PV6 increases as the secondary pilot pressure increases, and when the secondary pilot pressure is high, the sixth deceleration determination pressure PV6 is also a high value. When the secondary pilot pressure is low, the sixth deceleration determination pressure PV6 is also a low value.

In the sixth deceleration determination table T6, similarly to the fifth deceleration determination table T5 described above, the numerical value of the secondary pilot pressure indicates a boundary value for setting the sixth deceleration determination pressure PV6. For example, when the secondary pilot pressure is 1.6 MPa, the sixth deceleration determination pressure PV6 is 21 MPa.
The automatic deceleration unit 61 extracts the sixth deceleration determination pressure PV6 from the secondary pilot pressure and the sixth deceleration determination table T6 when the traveling motors (left traveling motor 36L, right traveling motor 36R) are at the second speed. .. The automatic deceleration unit 61 automatically decelerates when the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 are equal to or higher than the sixth deceleration determination pressure PV6 extracted from the sixth deceleration determination table T6. Specifically, the automatic deceleration unit 61 automatically decelerates when either the first differential pressure (V5) or the second differential pressure (V6) is equal to or higher than the sixth deceleration determination pressure PV6.

By the way, after the automatic deceleration is performed, the automatic deceleration unit 61 performs a return control when the automatic deceleration is effective.
A twelfth storage device 81l composed of a non-volatile memory or the like is connected to the control device 60. The 12th storage device 81l may be built in the control device 60.
As shown in FIG. 16B, the sixth return determination pressure QV6 is stored in the twelfth storage device 81l in association with the secondary pilot pressure. That is, the twelfth storage device 81l stores the sixth return determination table U6 showing the relationship between the secondary pilot pressure and the sixth return determination pressure QV6. In the sixth return determination table U6, the sixth return determination pressure QV6 increases as the secondary pilot pressure increases, and when the secondary pilot pressure is high, the sixth return determination pressure QV6 is also a high value. When the secondary pilot pressure is low, the sixth return determination pressure QV6 is also a low value. In the sixth return determination table U6, as in the sixth deceleration determination table T6 described above, the numerical value of the secondary pilot pressure indicates a boundary value for setting the sixth return determination pressure QV6. For example, when the secondary pilot pressure is 1.6 MPa, the sixth return determination pressure QV6 is 16 MPa.

After the automatic deceleration, the automatic deceleration unit 61 extracts the sixth return determination pressure QV6 from the secondary pilot pressure and the sixth return determination table U6, and the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 are the third. 6 When the return determination pressure QV6 or less extracted from the return determination table U6 is equal to or lower, the return control is executed. Specifically, the automatic deceleration unit 61 accelerates the traveling motor from the first speed to the second speed when the traveling differential pressures V5 and V6 become equal to or less than the sixth return determination pressure QV6.

FIG. 17 is a diagram summarizing the processes in the automatic deceleration unit 61.
As shown in FIG. 17, in the state where the automatic deceleration is effective and the traveling motor is at the second speed (S110, Yes), the automatic deceleration unit 61 refers to the secondary pilot pressure and the sixth deceleration determination table T6 ( S111). The automatic deceleration unit 61 extracts the sixth deceleration determination pressure PV6 from the sixth deceleration determination table T6 based on the secondary pilot pressure (S112). The differential pressure calculation unit 63 calculates the first differential pressure (V5) and the second differential pressure (V6) from the traveling pump pressures V1 to V4 (S113). The automatic deceleration unit 61 determines whether or not the first differential pressure (V5) and the second differential pressure (V6) are equal to or higher than the sixth deceleration determination pressure PV6 (S114). The automatic deceleration unit 61 automatically decelerates when the first differential pressure (V5) and the second differential pressure (V6) are equal to or higher than the sixth deceleration determination pressure PV6 (S114, Yes) (S115).

After performing automatic deceleration, the automatic deceleration unit 61 refers to the secondary pilot pressure and the sixth return determination table U6 (S116). The automatic deceleration unit 61 extracts the sixth return determination pressure QV6 from the sixth return determination table U6 based on the secondary pilot pressure (S117). The automatic deceleration unit 61 refers to the first differential pressure (V5) and the second differential pressure (V6) after the automatic deceleration (S118).
The automatic deceleration unit 61 determines whether or not the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the sixth return determination pressure QV6 (S119). When the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the sixth return determination pressure QV6 (S119, Yes), the automatic deceleration unit 61 performs return control (S120).

The work machine 1 includes an anti-stall valve 58, an eleventh storage device 81k, a control device 60 having an automatic deceleration unit 61 and a differential pressure calculation unit 63, and the automatic deceleration unit 61 has a traveling motor at a second speed. In this case, the sixth deceleration determination pressure PV6 is extracted from the secondary pilot pressure and the sixth deceleration determination table T6, and any of the traveling differential pressures V5 and V6 calculated by the differential pressure calculation unit 63 determines the sixth deceleration. When the pressure PV is 6 or more, automatic deceleration is performed. According to this, since automatic deceleration is performed based on the sixth deceleration determination pressure PV6 according to the secondary pilot pressure of the anti-stall valve 58, the work machine 1 is moved to the high speed side at the optimum timing in the operating state. It can be switched. In particular, automatic deceleration can be efficiently performed when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The work machine 1 includes a twelfth storage device 81l, and the automatic deceleration unit 61 extracts the sixth return determination pressure QV6 from the secondary pilot pressure and the sixth return determination table U6 after the automatic deceleration, and the differential pressure calculation unit. When both the traveling differential pressures V5 and V6 after the automatic deceleration calculated in 63 are equal to or less than the sixth return determination pressure QV6, the traveling motor is restored from the first speed to the second speed. According to this, since the return is performed based on the sixth return determination pressure QV6 according to the secondary pilot pressure of the anti-stall valve 58, the work machine 1 is switched to the high speed side at the optimum timing in the operating state. be able to. In particular, it is possible to efficiently recover after performing automatic deceleration when the loads applied to the left traveling device 5L and the right traveling device 5R are significantly different from each other.

The differential pressure calculation unit 63 uses the first differential pressure (V5), which is the difference between the first traveling pump pressure V1 and the third traveling pump pressure V3, and the second traveling pump pressure V2 and the fourth traveling as the traveling differential pressure. One of the second differential pressure (V6), which is the difference from the pump pressure V4, is obtained, and the automatic deceleration unit 61 decelerates either the first differential pressure (V5) or the second differential pressure (V6). When the determination pressure is PV6 or higher, automatic deceleration is performed. According to this, automatic deceleration can be efficiently performed in either the situation where the work machine 1 is moving forward or backward.

When both the first differential pressure (V5) and the second differential pressure (V6) are equal to or less than the sixth return determination pressure QV6, the automatic deceleration unit 61 sets at least one of the traveling motors from the first speed to the second. Return to speed. According to this, it is possible to efficiently return the work machine 1 in either the forward or reverse situation.
The eleventh storage device 81k stores the sixth deceleration determination table T6 in which the sixth deceleration determination pressure PV6 increases as the secondary pilot pressure increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.

The twelfth storage device 81l stores the sixth return determination table U6 in which the sixth return determination pressure QV6 increases as the secondary pilot pressure increases. According to this, in the work machine 1, work with a large work load can be efficiently performed.
In the control device 60, when the set speed of the traveling motor set by the operating member such as the operating lever 59 is set, the actual speed of any of the traveling motors does not exceed the set rotation speed. In addition, automatic deceleration may be performed. As shown in FIG. 2, a rotation detection device 88 for detecting the actual speed (actual rotation speed) ST1 of the traveling motors (left traveling motor 36L, right traveling motor 36R) is provided. For example, when the set speed (set rotation speed) of the traveling motors (left traveling motor 36L, right traveling motor 36R) set by the operating lever 59 by operating the operating lever 59 is "ST2", ST2> In the case of ST1, the control device 60 automatically decelerates.

Further, the control device 60 may return from the first speed to the second speed when the actual rotation speed ST1 of the traveling motor exceeds the set speed ST2 after the automatic deceleration. For example, after automatic deceleration, when ST1> ST2, the control device 60 returns from the first speed to the second speed.
As described above, since the second speed may be faster than the first speed, the working machine is not limited to two speeds, and can be applied to multiple speeds (multiple speeds).

In the above-described embodiment, the left travel motor 36L and the left travel motor 36R are simultaneously switched to the first speed and the second speed, and automatic deceleration is also performed for the left travel motor 36L and the left travel motor 36R at the same time. However, at least one of the left traveling motor 36L and the left traveling motor 36R is switched to the first speed and the second speed, and at least one of the left traveling motor 36L and the left traveling motor 36R is in the second speed. You may perform automatic deceleration with.

Further, the traveling motor (left traveling motor 36L, right traveling motor 36R) may be an axial piston motor or a radial piston motor. Regardless of whether the traveling motor is a radial piston motor or a radial piston motor, it is possible to switch to the first speed by increasing the motor capacity, and to switch to the second speed by decreasing the motor capacity.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1: Working machine 5L: Traveling device (left traveling device)
5R: Traveling device (right traveling device)
8: Driver's seat 32: Motor 34: Travel switching valve 36L: Travel motor (left travel motor)
36R: Traveling motor (right traveling motor)
53L: Traveling pump (left traveling pump)
53R: Traveling pump (right traveling pump)
57h: Connecting oil passage 57i: Connecting oil passage 60: Control device 61: Automatic deceleration unit 63: Differential pressure calculation unit 65: Accelerator 66: Mode switch 67: Speed changeover switch 68: Rotation speed detection device 76: Display unit 80: Running Pump pressure detection device 80a: 1st pressure detection device 80b: 2nd pressure detection device 80c: 3rd pressure detection device 80d: 4th pressure detection device 88: Rotation detection device P11: 1st port P12: 2nd port P13: 1st 3 port P14: 4th port PV1: 1st deceleration judgment pressure PV2: 2nd deceleration judgment pressure QV1: 1st return judgment pressure QV2: 2nd return judgment pressure T1: 1st deceleration judgment table T2: 2nd deceleration judgment table U1 : 1st return judgment table U2: 2nd return judgment table V: Traveling pump pressure V1: 1st traveling pump pressure V2: 2nd traveling pump pressure V3: 3rd traveling pump pressure V4: 4th traveling pump pressure V5: Traveling difference Pressure V6: Running differential pressure

Claims (6)

With the aircraft
With the prime mover
A pair of traveling devices provided on the left and right sides of the aircraft,
A pair of traveling motors capable of transmitting power to each of the left traveling device and the right traveling device and switching between a first speed and a second speed faster than the first speed.
A pair of traveling pumps driven by the power of the prime mover and supplying hydraulic oil to each of the pair of traveling motors.
A connecting oil passage connecting the pair of traveling motors and the pair of traveling pumps,
A traveling pump pressure detecting device that detects the pressure of the connecting oil passage as a traveling pump pressure, and
A rotation speed detection device that detects the rotation speed of the prime mover, which is the rotation speed of the prime mover, and
A third storage device that stores a second deceleration determination table showing the relationship between the prime mover rotation speed and the second deceleration determination pressure, and
When at least one of the pair of traveling motors is at the second speed, one of the pair of traveling motors and the automatic deceleration unit that automatically decelerates from the second speed to the first speed Difference in calculating the traveling differential pressure, which is the difference between the traveling pump pressure, which is the traveling pump pressure when driven, and the traveling pump pressure, which is the traveling pump pressure when the other of the pair of traveling motors is driven. A control device having a pressure calculation unit and
With
The automatic deceleration unit performs the second deceleration from the prime mover rotation speed detected by the rotation speed detection device and the second deceleration determination table when at least one of the pair of traveling motors has the second speed. A working machine that extracts a determination pressure and performs the automatic deceleration when the running differential pressure calculated by the differential pressure calculation unit is equal to or higher than the extracted second deceleration determination pressure. One of the traveling motors of the pair of traveling motors includes a first port connected to the connecting oil passage and a second port connected to the connecting oil passage.
The other traveling motor of the pair of traveling motors includes a third port connected to the connecting oil passage and a fourth port connected to the connecting oil passage.
The traveling pump pressure detecting device includes a first pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the first port side as the first traveling pump pressure.
The traveling pump pressure detecting device includes a second pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the second port side as the second traveling pump pressure.
The traveling pump pressure detecting device includes a third pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the third port side as the third traveling pump pressure.
The traveling pump pressure detecting device includes a fourth pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the fourth port side as the fourth traveling pump pressure.
Including
The differential pressure calculation unit has the first differential pressure, which is the difference between the first traveling pump pressure and the third traveling pump pressure, and the second traveling pump pressure and the fourth traveling pump as the traveling differential pressure. Find one of the second differential pressures, which is the difference from the pressure,
The working machine according to claim 1, wherein the automatic deceleration unit performs the automatic deceleration when either the first differential pressure or the second differential pressure is equal to or higher than the second deceleration determination pressure. The working machine according to claim 1 or 2, wherein the third storage device stores a second deceleration determination table in which the second deceleration determination pressure increases as the engine speed increases. With the aircraft
With the prime mover
A pair of traveling devices provided on the left and right sides of the aircraft,
A pair of traveling motors capable of transmitting power to each of the left traveling device and the right traveling device and switching between a first speed and a second speed faster than the first speed.
A pair of traveling pumps driven by the power of the prime mover and supplying hydraulic oil to each of the pair of traveling motors.
A connecting oil passage connecting the pair of traveling motors and the pair of traveling pumps,
A traveling pump pressure detecting device that detects the pressure of the connecting oil passage as a traveling pump pressure, and
A rotation speed detection device that detects the rotation speed of the prime mover, which is the rotation speed of the prime mover, and
A fourth storage device for storing a second return determination table showing the relationship between the prime mover rotation speed and the second return determination pressure is provided.
When at least one of the pair of traveling motors is at the second speed, one of the pair of traveling motors and the automatic deceleration unit that automatically decelerates from the second speed to the first speed Difference in calculating the traveling differential pressure, which is the difference between the traveling pump pressure, which is the traveling pump pressure when driven, and the traveling pump pressure, which is the traveling pump pressure when the other of the pair of traveling motors is driven. A control device having a pressure calculation unit and
With
The automatic deceleration unit extracts the second return determination pressure from the motor rotation speed detected by the rotation speed detection device and the second return determination table after the automatic deceleration, and is calculated by the differential pressure calculation unit. When the traveling differential pressure after automatic deceleration is equal to or less than the extracted second return determination pressure, a working machine that returns at least one of the pair of traveling motors from the first speed to the second speed. .. One of the traveling motors of the pair of traveling motors includes a first port connected to the connecting oil passage and a second port connected to the connecting oil passage.
The other traveling motor of the pair of traveling motors includes a third port connected to the connecting oil passage and a fourth port connected to the connecting oil passage.
The traveling pump pressure detecting device is
A first pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the first port side as the first traveling pump pressure, and
A second pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the second port side as the second traveling pump pressure, and
A third pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the third port side as the third traveling pump pressure, and
A fourth pressure detecting device that detects the traveling pump pressure for detecting the pressure of the connecting oil passage on the fourth port side as the fourth traveling pump pressure, and
Including
The differential pressure calculation unit uses the first differential pressure, which is the difference between the first traveling pump pressure and the third traveling pump pressure, the second traveling pump pressure, and the fourth traveling pump pressure as the traveling differential pressure. Find the second differential pressure, which is the difference between
When the first differential pressure and the second differential pressure are equal to or lower than the second return determination pressure, the automatic deceleration unit changes at least one of the pair of traveling motors from the first speed to the second speed. The working machine according to claim 4 to be restored. The working machine according to claim 4 or 5, wherein the fourth storage device stores a second return determination table in which the second return determination pressure increases as the rotation speed of the prime mover increases.