JP2020133201A - Work machine - Google Patents

Abstract

To enable a gear change shock to be easily reduced.SOLUTION: A work machine comprises: a motor; a travel pump capable of changing a discharge flow rate of hydraulic fluid depending on an angle of a swash plate; a travel motor that can be rotated by the hydraulic fluid discharged from the travel pump and whose rotary speed can be switched between the first speed and the second speed that is higher than the first speed; a travel switching valve that can be switched between the first state to make the rotary speed of the travel motor the first speed and the second state to make the rotary speed of the travel motor the second speed; and a controller that decreases the angle of the swash plate of the travel pump when switching from the second state to the first state.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 hydraulic system of the working machine of Patent Document 1 includes a hydraulic pump that discharges hydraulic oil, a hydraulic switching valve that can switch to a plurality of switching positions according to the pressure of the hydraulic oil, and a speed according to the switching position of the hydraulic switching valve. Is equipped with a variable traveling hydraulic system.

JP-A-2017-179922

In the working machine of Patent Document 1, since the bleed oil passage is provided in the pressure receiving portion of the hydraulic switching valve, it is possible to reduce the shift shock when the working machine is accelerated or decelerated. However, in Patent Document 1, a bleed oil passage must be provided in order to reduce shift shock, and the number of parts increases. Further, in a traveling motor having no neutrality, it is required to further sufficiently reduce the shift shock.

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 easily reducing a shift shock.

The technical measures taken by the present invention to solve the technical problems are as follows.
The working machine can be rotated by the prime mover, a traveling pump that can change the flow rate of the hydraulic oil discharged according to the angle of the swash plate, and the hydraulic oil discharged by the traveling pump, and the rotation speed is the first speed. A traveling motor that can be switched to a second speed higher than the first speed, a first state in which the rotation speed of the traveling motor is set to the first speed, and a rotation speed of the traveling motor to be set to the second speed. It is provided with a traveling switching valve capable of switching to the second state, and a control device for reducing the angle of the swash plate of the traveling pump when switching from the second state to the first state.

The working machine includes a switching unit that gives a command to switch between the first state and the second state, and an operating device that can change the angle of the swash plate of the traveling pump. The control device is the switching unit. When the command is given to the first state, the angle of the swash plate of the traveling pump is lowered from the target angle which is the angle of the swash plate set by the operating device, and then the traveling switching is performed. The valve is switched to the first state.

The control device restores the angle of the swash plate of the traveling pump at least after switching the traveling switching valve to the first state.
The control device makes the return time for returning the angle of the swash plate shorter than the reduction time for lowering the swash plate of the traveling pump.
The working machine includes a machine body provided with the prime mover, a traveling pump, and a traveling motor, and a traveling detection device capable of detecting the traveling speed of the aircraft, and the control device is traveling detected by the traveling detection device. The amount of decrease in the angle of the swash plate is set according to the speed.

The working machine includes a machine body provided with the prime mover, a traveling pump, and a traveling motor, and the control device reduces the angle of the swash plate when the machine body is in a traveling state.
The working machine includes a machine body, a first traveling device provided on the left side of the machine body, and a second traveling device provided on the right side of the machine body, and the traveling motor travels on the first traveling device. The first traveling motor for transmitting the power of the above and the second traveling motor for transmitting the traveling power to the second traveling device, and the traveling pump can operate the first traveling motor and the second traveling motor. The traveling switching valve can switch the first traveling motor and the second traveling motor between the first speed and the second speed.

The switching unit is a switching switch that outputs a command to switch between the first state and the second state to the control device.

According to the present invention, shift shock can be easily reduced.

It is a figure which shows the hydraulic system (hydraulic circuit) of the work machine in 1st Embodiment. It is a figure which showed the relationship between the rotation speed of a prime mover and the switching of a traveling motor when the speed of a traveling motor is increased. It is a figure which showed the relationship between the rotation speed of a prime mover and the switching of a traveling motor when the traveling motor is decelerated. It is a figure which showed the 1st operation flow of the control device at the time of speeding up a traveling motor. It is a figure which showed the 2nd operation flow of the control device at the time of decelerating a traveling motor. It is a figure which showed the relationship between the swash plate angle of a traveling pump and the switching of a traveling motor when the speed of a traveling motor is increased. It is a figure which showed the relationship between the swash plate angle of a traveling pump and the switching of a traveling motor when the traveling motor is decelerated. It is a figure which showed the 3rd operation flow of the control device at the time of increasing the speed of a traveling motor. It is a figure which showed the 4th operation flow of the control device when the traveling motor was decelerated. It is a figure which shows the hydraulic system (hydraulic circuit) of the work machine in 2nd Embodiment. It is a figure which shows the modification of the hydraulic system (hydraulic circuit) of a working machine. It is a table which shows the relationship with the actual rotation speed W1 of a prime mover, a traveling pilot pressure, and the decrease amount ΔD1 of a prime mover rotation speed. It is a graph of FIG. 8A. It is a table which shows the relationship between the traveling pilot pressure and the decrease amount (decrease amount ΔD2) of a traveling pilot pressure. 9A is a graph of FIG. 9A. 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.
[First Embodiment]
FIG. 10 shows a side view of the working machine according to the present invention. FIG. 10 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. 10, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a traveling device 5. In the embodiment of the present invention, the front side (left side of FIG. 10) 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. 10) is the rear, and the left side of the driver (FIG. 10). The front side of 10 will be described as the left side, and the right side of the driver (the back side of FIG. 10) 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 traveling device 5 is 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 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.
As each of the left and right traveling devices (first traveling device, second traveling device) 5, 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.

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 can drive the traveling device 5. The hydraulic system of the working machine includes a first traveling pump 53L, a second traveling pump 53R, a first traveling motor 36L, and a second traveling motor 36R.

The first traveling pump 53L and the second traveling pump 53R are pumps driven by the power of the prime mover 32. Specifically, the first traveling pump 53L and the second traveling pump 53R are swash plate type variable capacitance axial pumps driven by the power of the prime mover 32. The first traveling pump 53L and the second traveling pump 53R are inclined by the pilot pressure acting on the pressure receiving portions 53a and 53b, which have the forward pressure receiving portion 53a on which the pilot pressure acts and the reverse pressure receiving portion 53b. The angle of the board is changed. 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 first traveling pump 53L and the second traveling pump 53R can be changed.

The first traveling pump 53L and the first traveling motor 36L are connected by a circulation oil passage 57h, and the hydraulic oil discharged by the first traveling pump 53L is supplied to the first traveling motor 36L. The second traveling pump 53R and the second traveling motor 36R are connected by a circulation oil passage 57i, and the hydraulic oil discharged by the second traveling pump 53R is supplied to the second traveling motor 36R.
The first traveling motor 36L is a motor that transmits power to the drive shaft of the traveling device 5 provided on the left side of the machine body 2. The first traveling motor 36L can be rotated by the hydraulic oil discharged from the first 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 first traveling motor 36L, and the rotation speed (rotation speed) of the first traveling motor 36L is also changed by expanding and contracting the swash plate switching cylinder 37L to one side or the other side. be able to. That is, when the swash plate switching cylinder 37L is contracted, the rotation speed of the first traveling motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is extended, the first traveling motor 36L is set. The rotation speed of is set to high speed (second speed). That is, the rotation speed of the first 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 second traveling motor 36R is a motor that transmits power to the drive shaft of the traveling device 5 provided on the right side of the machine body 2. The second traveling motor 36R can be rotated by the hydraulic oil discharged from the second 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 second traveling motor 36R, and the rotation speed (rotation speed) of the second traveling motor 36R is also changed by expanding and contracting the swash plate switching cylinder 37R to one side or the other side. be able to. That is, when the swash plate switching cylinder 37R is contracted, the rotation speed of the second traveling motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is extended, the second traveling motor 36R is set. The rotation speed of is set to high speed (second speed). That is, the rotation speed of the second 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 switches between a first state in which the rotation speed (rotation speed) of the travel motors (first travel motor 36L, second travel motor 36R) is set to the first speed and a second state in which the travel speed is set to the second speed. It is possible. 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 first 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 second switching valve 71R is a two-position switching valve that is connected to the swash plate switching cylinder 37R of the second traveling motor 36R via an oil passage and switches between the first position 71R1 and the second position 71R2. The second switching valve 71R contracts the swash plate switching cylinder 37R at the first position 71R1 and expands 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 second 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 second switching valve 71R are connected by an oil passage 41. The second switching valve 72 switches the first switching valve 71L and the second 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 second 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 motors (first traveling motor 36L, second 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 second 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 (first traveling motor 36L, second traveling motor 36R) is set to the second speed.

Therefore, the traveling switching valve 34 can switch the traveling motors (first traveling motor 36L, second traveling motor 36R) between the first speed on the low speed side and the second speed on the high speed side.
Switching between the first speed and the second speed in the traveling motor can be performed by the switching unit. The switching unit is, for example, a changeover switch 61 connected to the control device 60, and can be operated by an operator or the like. The switching unit (changeover switch 61) increases the speed of switching from the first speed (first state) to the second speed (second state), and changes from the second speed (second state) to the first speed (first state). It can be switched to either deceleration or switching.

The control device 60 is composed of a CPU, a semiconductor such as an MPU, an electric / electronic circuit, and the like. The control device 60 switches the traveling switching valve 34 based on the switching operation of the changeover switch 61. The changeover switch 61 is a push switch. For example, when the traveling motor is pressed in the first speed state, the changeover switch 61 outputs a command to set the traveling motor to the second speed (a command to set the traveling switching valve 34 to the second speed) to the control device 60. Will be done. Further, when the traveling motor is pressed in the state of the second speed, the changeover switch 61 outputs a command to set the traveling motor to the first speed (a command to set the traveling switching valve 34 to the first state) to the control device 60. .. The changeover switch 61 may be a push switch that can be held ON / OFF, and when it is OFF, a command for holding the traveling motor at the first speed is output to the control device 60 and is ON. In this case, a command for holding the traveling motor at the second speed is output to the control device 60.

When the control device 60 obtains a command to put the traveling switching valve 34 into the first state, the control device 60 degausses the solenoid of the second switching valve 72 to put the traveling switching valve 34 into the first state. Further, when the control device 60 obtains a command to bring the traveling switching valve 34 into the second state, the control device 60 activates the solenoid of the second switching valve 72 to bring the traveling switching valve 34 into the second state.
By the way, the hydraulic system of the working machine includes a first hydraulic pump P1, a second hydraulic pump P2, and an operating device 54. 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.

The operation device 54 is a device for operating the traveling pumps (first traveling pump 53L, second 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 operation lever 59 is an operation lever that is supported by the operation 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 from the neutral position N to the right and left, 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. A discharge oil passage 40 is 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 passage 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 an operation that outputs 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 (first traveling pump 53L, second traveling pump 53R) are connected by a traveling oil passage 45. In other words, the traveling pump (first traveling pump 53L, second traveling pump 53R) is hydraulically operated by the hydraulic oil output from the operating valve 55 (operating valve 55A, operating valve 55B, operating valve 55C, operating valve 55D). It is a device.
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 first traveling pump 53L via the first traveling oil passage 45a and acts on the pressure receiving portion 53a of the second traveling pump 53R via the third traveling oil passage 45c. As a result, the swash plate angles of the first traveling pump 53L and the second traveling pump 53R are changed, the first traveling motor 36L and the second 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 first traveling pump 53L via the second traveling oil passage 45b and acts on the pressure receiving portion 53b of the second traveling pump 53R via the fourth traveling oil passage 45d. As a result, the angle of the swash plate of the first traveling pump 53L and the second traveling pump 53R is changed, the first traveling motor 36L and the second 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 first traveling pump 53L via the first traveling oil passage 45a and acts on the pressure receiving portion 53b of the second traveling pump 53R via the fourth traveling oil passage 45d. As a result, the swash plate angles of the first traveling pump 53L and the second traveling pump 53R are changed, the first traveling motor 36L rotates forward and the second traveling motor 36R reverses, and the working 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 second traveling pump 53R via the third traveling oil passage 45c and acts on the pressure receiving portion 53b of the first traveling pump 53L via the second traveling oil passage 45b. As a result, the swash plate angles of the first traveling pump 53L and the second traveling pump 53R are changed, the first traveling motor 36L reverses, the second traveling motor 36R rotates forward, and the work machine 1 turns to the left.

Further, when the operating lever 59 is swung in the oblique direction, the rotation direction and rotation speed of the first traveling motor 36L and the second traveling motor 36R are changed by the differential pressure of the pilot pressure acting on the pressure receiving portion 53a and the pressure receiving portion 53b. Determined, 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.

By the way, the accelerator 65 for setting the prime mover rotation speed is connected to the control device 60. The accelerator 65 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. Further, a rotation detection device 66 for detecting the rotation speed of the prime mover is connected to the control device 60. The rotation detection device 66 allows the control device 60 to grasp the actual motor rotation speed (actual rotation speed) of the prime mover 32.

The control device 60 sets a target prime mover rotation speed (target rotation speed) based on the operation amount of the accelerator 65, and controls the actual rotation speed so as to reach the set target rotation speed.
By the way, when the control device 60 switches the traveling switching valve 34 from the first state (first speed) to the second state (second speed), that is, the rotation speed of the traveling motor is changed from the first speed to the second speed. When speeding up, the prime mover speed is reduced.

The control device 60 reduces the rotation speed of the prime mover based on the traveling state of the working machine (machine body 2). For example, when the speed is increased, the control device 60 reduces the rotation speed of the prime mover when the working machine (machine 2) is running in the running state, and the working machine (body 2) is stopped in the running state. If so, do not reduce the engine speed.
FIG. 2A is a diagram showing the relationship between the rotation speed (target rotation speed, actual rotation speed) of the prime mover when the traveling motor is accelerated from the first speed to the second speed and the switching of the traveling motor.

As shown in FIG. 2A, in the control device 60, the changeover switch (changeover SW) 61 is operated at the time point Q1, and the control device 60 is in the first state (first speed) to the second state (second speed). It is assumed that the speed increase command (second speed command) is acquired. When the control device 60 acquires the second speed command, the actual rotation speed W1 is reduced to a predetermined rotation speed W3, which is lower than the target rotation speed W2 set by the accelerator 65. The predetermined rotation speed W3 is a rotation speed that reduces the shift shock when switching from the first speed to the second speed, and is, for example, a value obtained by subtracting the reduction amount ΔD1 from the actual rotation speed W1.

The control device 60 sets the reduction amount ΔD1 according to the traveling speed of the working machine (machine body 2), which is one of the traveling states. Specifically, a travel detection device 67 that detects a travel speed as a travel state is connected to the control device 60. The travel detection device 67 detects and detects, for example, the pressure (pilot pressure) of the hydraulic oil (pilot oil) output from the operation valve 55 (operation valve 55A, operation valve 55B, operation valve 55C, operation valve 55D). It is a device that converts pilot pressure into running speed. For example, when the pilot pressure of the traveling oil passage 45 is high, the traveling speed is high, and when the pilot pressure is low, the traveling speed is detected to be low. The travel detection device 67 detects the travel speed from the pilot pressure of the travel oil passage 45. Instead, the travel detection device 67 detects the rotation speed of the rotation shaft of the travel motor and travels on the detected rotation speed. It may be a device that converts the speed into any device as long as the traveling speed can be detected.
That is, when switching to speed increase, the control device 60 sets a decrease amount ΔD1 corresponding to the travel speed detected by the travel detection device 67, and decreases the prime mover rotation speed corresponding to the set decrease amount ΔD1.

As shown in FIG. 8A, the control device 60 stores the reduction amount calculation data showing the relationship between the actual rotation speed W1, the pilot pressure (traveling pilot pressure) of the traveling oil passage 45, and the reduction amount ΔD1. FIG. 8B is a graph of FIG. 8A. The reduction amount calculation data in FIGS. 8A and 8B are examples and are not limited.
For example, as shown in FIG. 8A, the control device 60 sets the reduction amount ΔD1 to 500 rpm when the actual rotation speed W1 is 3000 rpm and the traveling pilot pressure is 1.5 MPa when the second speed command is acquired. As shown in FIG. 8A, the control device 60 sets a lower limit value of the prime mover rotation speed so as not to be smaller than the minimum prime mover rotation speed when the prime mover rotation speed is lowered. Further, in reducing the prime mover rotation speed, the control device 60 keeps the inclination K1 (inclination of the decrease time T1) for reducing the prime mover rotation speed constant even if the decrease amount ΔD1 is different.

When the actual rotation speed W1 reaches the predetermined rotation speed W3 at the time point Q2, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2. Alternatively, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2 on the way during the reduction time T1 for reducing the actual rotation speed W1 to the predetermined rotation speed W3. Here, the control device 60 sets the return time T2 for returning the actual rotation speed W1 from the predetermined rotation speed W3 to the target rotation speed W2 longer than the decrease time T1. That is, the control device 60 makes the reduction speed at which the actual rotation speed W1 is reduced to the predetermined rotation speed W3 faster than the return speed at which the actual rotation speed W1 is returned from the predetermined rotation speed W3 to the target rotation speed W2.

Further, the control device 60 sends a signal for exciting the solenoid of the traveling switching valve 34 at least during the decrease time T1, that is, before starting the control for returning the actual rotation speed W1 from the predetermined rotation speed W3 to the target rotation speed W2. Output to switch the traveling switching valve (switching valve) 34 from the first state (first speed) to the second state (second speed). In other words, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2 after switching the traveling switching valve 34 to the second state.

FIG. 3A is a diagram showing a control flow of the control device 60 when the rotation speed of the traveling motor is changed from the first speed to the second speed. It should be noted that the working machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the changeover switch 61 has been switched from the first speed to the second speed (S1). When the changeover switch 61 is not switched to the second speed, that is, is maintained at the first speed (S1, No), the control device 60 sets the actual rotation speed W1 as the target rotation based on the operation of the accelerator 65. Set to several W2 (S2). When the changeover switch 61 is switched from the first speed to the second speed (S1, Yes), the control device 60 lowers the actual rotation speed W1 toward the predetermined rotation speed W3 lower than the target rotation speed W2 (S3). ). The control device 60 switches the traveling switching valve 34 from the first state (first speed) to the second state (second speed) before the actual rotation speed W1 reaches the predetermined rotation speed W3 (S4). ). The control device 60 determines whether or not the actual rotation speed W1 has reached the predetermined rotation speed W3 (S5), and when the actual rotation speed W1 reaches the predetermined rotation speed W3 (S5, Yes), the actual rotation speed W1 is set. It returns to the target rotation speed W2 (S6). When the actual rotation speed W1 has not reached the predetermined rotation speed W3 (S5, No), the control device 60 lowers the actual rotation speed W1 toward the predetermined rotation speed W3 (S3), and lowers the traveling switching valve 34. , When the first state (first speed) has already been switched to the second state (second speed) (when the processing of S4 has already been performed), the processing of S4 is skipped and the process shifts to the processing of S5. To do. Further, in the control device 60, the process of lowering the actual rotation speed W1 toward the predetermined rotation speed W3 and the process of switching the traveling switching valve 34 may be individually processed in parallel.

By the way, in the above-described embodiment, when the working machine 1 is increased from the first speed to the second speed, the rotation speed of the prime mover is lowered, but the working machine 1 is decelerated from the second speed to the first speed. In some cases, the prime mover speed may be reduced.
The control device 60 switches the travel switching valve 34 from the second state (second speed) to the first state (first speed), that is, when the rotation speed of the travel motor is switched from the second speed to the first speed. To reduce the motor speed. For example, when the control device 60 is decelerating and the working machine (machine 2) is running in the running state, the rotation speed of the prime mover is lowered and the working machine (body 2) is stopped in the running state. In that case, the engine speed is not reduced.

FIG. 2B is a diagram showing the relationship between the rotation speed (target rotation speed, actual rotation speed) of the prime mover when the traveling motor is decelerated from the first speed to the second speed and the switching of the traveling motor.
As shown in FIG. 2B, in the control device 60, the changeover switch (changeover SW) 61 is operated at the time point Q11, and the control device 60 changes from the second state (second speed) to the first state (first speed). It is assumed that the deceleration command (1st speed command) is acquired. When the control device 60 acquires the first speed command, the actual rotation speed W1 is reduced to a predetermined rotation speed W4, which is lower than the target rotation speed W2 set by the accelerator 65. The predetermined rotation speed W4 is a rotation speed that reduces the shift shock when switching from the second speed to the first speed, and is set by, for example, the amount of decrease ΔD1 from the target rotation speed W2. The setting of the reduction amount ΔD1 is the same as that of the above-described embodiment, and the control device 60 sets and sets the reduction amount ΔD1 corresponding to the travel speed detected by the travel detection device 67 when switching to deceleration. The prime mover speed is reduced corresponding to the reduction amount ΔD1. Further, in reducing the prime mover rotation speed, the control device 60 keeps the inclination K2 (inclination of the decrease time T11) for reducing the prime mover rotation speed constant even when the decrease amount ΔD1 is different.

When the actual rotation speed W1 reaches the predetermined rotation speed W4 at the time point Q12, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2. Alternatively, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2 on the way during the reduction time T11 for reducing the actual rotation speed W1 to the predetermined rotation speed W4. Here, the control device 60 makes the return time T12 for returning the actual rotation speed W1 from the predetermined rotation speed W4 to the target rotation speed W2 shorter than the reduction time T11. That is, the control device 60 makes the reduction speed at which the actual rotation speed W1 is reduced to the predetermined rotation speed W3 slower than the return speed at which the actual rotation speed W1 is returned from the predetermined rotation speed W3 to the target rotation speed W2.

Further, the control device 60 outputs a signal for degaussing the solenoid of the traveling switching valve 34 before returning the actual rotation speed W1 from the predetermined rotation speed W4 to the target rotation speed W2, and the traveling switching valve (switching valve) 34. Is switched from the second state (second speed) to the first state (first speed). In other words, the control device 60 returns the actual rotation speed W1 to the target rotation speed W2 after switching the traveling switching valve 34 to the first state.

FIG. 3B is a diagram showing a control flow of the control device 60 when the rotation speed of the traveling motor is changed from the second speed to the first speed. It should be noted that the working machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the changeover switch 61 has been switched from the second speed to the first speed (S11). When the changeover switch 61 is not switched to the first speed, that is, is maintained at the second speed (S11, No), the control device 60 sets the actual rotation speed W1 as the target rotation based on the operation of the accelerator 65. Set to the number W2 (S12). When the changeover switch 61 is switched from the second speed to the first speed (S11, Yes), the control device 60 reduces the actual rotation speed W1 to a predetermined rotation speed W4 lower than the target rotation speed W2 (S13). The control device 60 determines whether or not the actual rotation speed W1 has reached the predetermined rotation speed W4 (S14), and after the actual rotation speed W11 reaches the predetermined rotation speed W4 (S14, Yes), the control device 60 , The traveling switching valve 34 is switched from the second state (second speed) to the first state (first speed) (S15). The control device 60 returns the actual rotation speed W1 to the target rotation speed W2 (S16).

The work machine 1 controls a prime mover 32, a traveling pump (first traveling pump 53L, second traveling pump 53R), a traveling motor (first traveling motor 36L, second traveling motor 36R), and a traveling switching valve 34. The control device 60 includes the device 60, and the control device 60 is based on the running state of the aircraft 2 when switching to either the speed increase for switching from the first state to the second state or the deceleration for switching from the second state to the first state. To reduce the motor speed. According to this, in both the case of increasing the speed of the work machine 1 and the case of decelerating, the prime mover rotation speed is lowered according to the running state, so that the shock of shifting is changed according to the running state. Can be reduced.

The control device 60 does not reduce the prime mover rotation speed when the machine body 2 is running in the running state, and does not lower the prime mover rotation speed when the machine body 2 is stopped in the running state. According to this, it is possible to further reduce the shock of shifting when the machine body 2 is traveling.
The control device 60 corresponds to the running speed detected by the running detection device 67 when switching to either the speed increase for switching from the first state to the second state or the deceleration for switching from the second state to the first state. A decrease amount ΔD1 of the prime mover rotation speed is set, and the prime mover rotation speed is decreased corresponding to the set decrease amount ΔD1. According to this, in both the case of increasing the speed of the working machine 1 and the case of decelerating it, the number of revolutions of the prime mover is decreased according to the traveling speed, so that the traveling speed is in any state. However, the shock of shifting can be reduced.

Further, when the switching unit (changeover switch 61) issues a shift command, the control device 60 travels after lowering the prime mover rotation speed from the target rotation speed which is the prime mover rotation speed set by the accelerator 65. The switching valve 34 is switched to either the first state or the second state according to the shift command. According to this, in order to lower the prime mover rotation speed from the target rotation speed set by the accelerator 65 before the speed increase or deceleration of the work machine 1, the traveling pump is used at the time of either speed increase or deceleration. The flow rate of the hydraulic oil discharged from the engine can be temporarily reduced, whereby the shift shock can be reduced.

The control device 60 restores the prime mover rotation speed after switching the traveling switching valve 34. According to this, after the prime mover rotation speed is lowered in order to reduce the shift shock, the prime mover rotation speed can be brought to the state before deceleration as soon as possible.
In the case of speed increase, the control device 60 makes the return time T2 for returning the prime mover rotation speed longer than the decrease time T1 for lowering the prime mover rotation speed, and makes the return time T12 shorter than the decrease time T11 in the case of deceleration. To do. According to this, after the shift shock is reduced, the shift shock can be reduced as much as possible in the situation where the prime mover rotation speed is returned as soon as possible before the shift.

[Second Embodiment]
FIG. 6 shows the hydraulic system of the working machine according to the second embodiment. In the second embodiment, not only the swash plate angle of the traveling pump (first traveling pump 53L, second traveling pump 53R) is changed by the operating device 154, but also the swash plate angle of the traveling pump is changed by the control device 60. be able to. Note that FIG. 6 shows a traveling pump (first traveling pump 53L, second traveling pump 53R), an operating device 154, and a control device 60, but other parts are the same as those in FIG.

The operation device 154 is a joystick type device that changes the angle of the slanted plate of the traveling pump by electricity, and is an operation detection device (sensor) that converts the operation lever 59 and the operation amount and operation direction of the operation lever 59 into an electric signal. It has 82 and. When the operation lever 59 is operated to the right, left, front, and rear, the operation detection device 82 detects the operation amount and the operation direction, and the detected operation amount and the operation direction are input to the control device 60. The control device 60 changes the swash plate angle of the traveling pump based on the operation amount and the operation direction detected by the operation detection device 82. Specifically, the traveling pumps (first traveling pump 53L, second traveling pump 53R) have a regulator 155 that changes the angle of the swash plate, and the control device 60 controls the regulator 155 to tilt the swash plate. Change the plate angle. In the traveling pumps (first traveling pump 53L, second traveling pump 53R), the flow rate of the hydraulic oil discharged increases as the swash plate angle increases, and the flow rate of the hydraulic oil discharged decreases as the swash plate angle decreases. Become. Further, an angle detection device 68 for detecting the swash plate angle is connected to the control device 60. The angle detection device 68 allows the control device 60 to grasp the actual swash plate angle (actual angle) of the traveling pump.

The control device 60 is a traveling pump (first traveling pump 53L, when the traveling switching valve 34 is switched from the first state to the second state (when the rotational speed of the traveling motor is increased from the first speed to the second speed). The angle of the sloping plate of the second traveling pump 53R) is reduced.
FIG. 4A is a diagram showing the relationship between the swash plate angle (target angle, actual angle) when the traveling motor is accelerated from the first speed to the second speed and the switching of the traveling motor.

As shown in FIG. 4A, in the control device 60, the changeover switch (switching valve) 61 is operated at the time point Q21, and the control device 60 is in the first state (first speed) to the second state (second speed). It is assumed that the command to be set (2-speed command) is acquired. When the control device 60 acquires the second speed command, the actual angle W11 of the traveling pumps (first traveling pump 53L, second traveling pump 53R) is set as a target of the swash plate angle set based on the operation amount of the operating device 154. The angle (target angle) is lowered to a predetermined angle W13 lower than W12. The predetermined angle W13 is an angle for reducing the shift shock when switching from the first speed to the second speed, and is a value obtained by subtracting the reduction amount ΔD2 from the actual angle W11.

As shown in FIG. 9A, the control device 60 stores the decrease amount calculation data showing the relationship between the travel pilot pressure and the decrease amount (decrease amount ΔD2) of the travel pilot pressure. FIG. 9B is a graph of FIG. 9A. The reduction amount calculation data of FIGS. 9A and 9B is an example and is not limited. Further, the traveling speed (vehicle speed) shown in FIG. 9A is a value shown for convenience of explanation, and is a value at a predetermined motor rotation speed, and is not limited.

Although the amount of decrease in the traveling pilot pressure is shown in FIGS. 9A and 9B, there is a correlation between the amount of decrease in the traveling pilot pressure and the amount of decrease in the swash plate angle ΔD2. That is, since the swash plate angle is controlled by the traveling pilot pressure, the higher the traveling pilot pressure, the larger the swash plate angle, and the lower the traveling pilot pressure, the smaller the swash plate angle.
For example, as shown in FIG. 9A, when the control device 60 acquires the second speed command and the traveling speed is 5.0 km / h (traveling pilot pressure: 1.5 MPa), the amount of decrease in the traveling pilot pressure is determined. Set to 0.50 MPa. As shown in FIG. 9A, the control device 60 has a swash plate angle (traveling pilot pressure) so that the swash plate angle, that is, the traveling pilot pressure does not become smaller than the minimum pilot pressure when the prime mover rotation speed is reduced. ) Is set.

When the actual angle W11 reaches the predetermined angle W13 at the time point Q22, the control device 60 returns the actual angle W11 to the target angle W12. Alternatively, the control device 60 returns the real angle W11 to the target angle W12 on the way during the lowering time T21 for lowering the real angle W11 to the predetermined angle W13. Here, the control device 60 sets the return time T22 for returning the actual angle W11 from the predetermined angle W13 to the target angle W12 longer than the reduction time T21. That is, the control device 60 makes the reduction speed for reducing the actual angle W11 to the predetermined angle W13 faster than the return speed for returning the actual angle W11 from the predetermined angle W13 to the target angle W12.

Further, the control device 60 outputs a signal for exciting the solenoid of the traveling switching valve 34 at least during the lowering time T21, that is, before starting the control for returning the actual angle W11 from the predetermined angle W13 to the target angle W12. , The traveling switching valve (switching valve) 34 is switched from the first state (first speed) to the second state (second speed). In other words, the control device 60 returns the actual angle W11 to the target angle W12 after switching the traveling switching valve 34 to the second state.

FIG. 5A is a diagram showing a control flow of the control device 60 when the rotation speed of the traveling motor is changed from the first speed to the second speed in the second embodiment. It should be noted that the working machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the changeover switch 61 has been switched from the first speed to the second speed (S21). When the changeover switch 61 is not switched to the second speed, that is, is maintained at the first speed (S21, No), the control device 60 sets the actual angle W11 at the target angle based on the operation of the operation device 154. Set to W12 (S22). When the changeover switch 61 is switched from the first speed to the second speed (S1, Yes), the control device 60 lowers the actual angle W11 toward the predetermined angle W13 lower than the target angle W12 (S23). The control device 60 switches the traveling switching valve 34 from the first state (first speed) to the second state (second speed) before the actual angle W11 reaches the predetermined angle W13 (S24). The control device 60 determines whether or not the actual angle W11 has reached the predetermined angle W13 (S25), and when the actual angle W11 has reached the predetermined angle W13 (S25, Yes), the actual angle W11 is set to the target angle W12. (S26).

When the actual angle W11 does not reach the predetermined angle W13 (S25, No), the control device 60 lowers the actual angle W11 toward the predetermined angle W13 (S23), and already sets the traveling switching valve 34 to the first position. When switching from the state (first speed) to the second state (second speed) (when the processing of S24 has already been performed), the processing of S24 is skipped and the process proceeds to the processing of S25. Further, in the control device 60, the process of lowering the actual angle W11 toward the predetermined angle W13 and the process of switching the traveling switching valve 34 may be individually processed in parallel.

The working machine 1 controls a prime mover 32, a traveling pump (first traveling pump 53L, second traveling pump 53R), a traveling motor (first traveling motor 36L, second traveling motor 36R), a traveling switching valve 34, and a traveling switching valve 34. A device 60 is provided, and the control device 60 lowers the swash plate angle of the traveling pump when switching from the first state to the second state. According to this, it is possible to reduce the shock of shifting when the speed of the working machine 1 is increased (when switching from the first state to the second state).

The work machine 1 includes an operation device 154 capable of changing the swash plate angle of the traveling pump, and the control device 60 has an inclination set by the operation device 154 when a command to make the second state is acquired by the changeover switch 61. After lowering the swash plate angle of the traveling pump from the target angle which is the plate angle, the traveling switching valve 34 is switched to the second state. According to this, since the actual angle is lowered from the target angle set by the operating device 154 before the speed increase of the work machine 1, the flow rate of the hydraulic oil discharged from the traveling pump is temporarily increased at the time of speed increase. It can be reduced, which can reduce shift shock.

The control device 60 restores the swash plate angle of the traveling pump after switching the traveling switching valve 34 to the second state. According to this, after the actual angle is lowered in order to reduce the shift shock, the actual angle can be brought to the state before the speed increase as soon as possible.
The control device 60 makes the return time T22 for returning the swash plate angle longer than the reduction time T21 for lowering the swash plate angle of the traveling pump. According to this, after reducing the shift shock, the shift shock at the time of speed increase can be reduced as much as possible in the situation where the actual angle is returned as soon as possible before speeding up.

The control device sets the amount of decrease in the swash plate angle according to the traveling speed detected by the traveling detection device. According to this, it is possible to reduce the shift shock according to the traveling speed.
By the way, in the above-described embodiment, when the working machine 1 is increased from the first speed to the second speed, the swash plate angle of the traveling pump is lowered, but the working machine 1 is moved from the second speed to the first speed. When decelerating to, the swash plate angle may be lowered.

The control device 60 is a traveling pump (first traveling pump 53L, first) when the traveling switching valve 34 is switched from the second state to the first state (when the rotation speed of the traveling motor is reduced from the second speed to the first speed). 2 The traveling pump 53R) is lowered.
FIG. 4B is a diagram showing the relationship between the swash plate angle (target angle, actual angle) when the traveling motor is decelerated from the second speed to the first speed, and the switching of the traveling motor.

As shown in FIG. 4B, in the control device 60, the changeover switch (changeover SW) 61 is operated at the time point Q31, and the control device 60 changes from the second state (second speed) to the first state (first speed). It is assumed that the command to be set (1st speed command) is acquired. When the control device 60 acquires the first speed command, the actual angle W11 of the traveling pumps (first traveling pump 53L, second traveling pump 53R) is set as a target of the swash plate angle set based on the operation amount of the operating device 154. It is lowered to a predetermined angle W14, which is lower than the angle W12.

When the actual angle W11 reaches the predetermined angle W14 at the time point Q32, the control device 60 returns the actual angle W11 to the target angle W12. Alternatively, the control device 60 returns the real angle W11 to the target angle W12 on the way during the lowering time T31 for lowering the real angle W11 to the predetermined angle W14. Here, the control device 60 shortens the return time T32 for returning the actual angle W11 from the predetermined angle W14 to the target angle W12 shorter than the reduction time T31. That is, the control device 60 makes the lowering speed for lowering the real angle W11 to the predetermined angle W14 slower than the returning speed for returning the real angle W11 from the predetermined angle W14 to the target angle W12.

Further, the control device 60 outputs a signal for degaussing the solenoid of the traveling switching valve 34 at least during the lowering time T31, that is, before starting the control for returning the actual angle W11 from the predetermined angle W14 to the target angle W12. , The traveling switching valve 34 is switched from the second state (second speed) to the first state (first speed). In other words, the control device 60 returns the actual angle W11 to the target angle W12 after switching the traveling switching valve 34 to the first state.

FIG. 5B is a diagram showing a control flow of the control device 60 when the rotation speed of the traveling motor is changed from the second speed to the first speed in the second embodiment. It should be noted that the working machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the changeover switch 61 has been switched from the second speed to the first speed (S31). When the changeover switch 61 is not switched to the second speed, that is, is maintained at the second speed (S31, No), the control device 60 sets the actual angle W11 at the target angle based on the operation of the operation device 154. Set to W12 (S32). When the changeover switch 61 is switched from the second speed to the first speed (S31, Yes), the control device 60 lowers the actual angle W11 to a predetermined angle W14 lower than the target angle W12 (S33). The control device 60 determines whether or not the actual angle W11 has reached the predetermined angle W14 (S34), and after the actual angle W11 reaches the predetermined angle W14 (S34, Yes), the control device 60 sets the traveling switching valve. The 34 is switched from the second state (second speed) to the first state (first speed) (S35). The control device 60 returns the actual angle W11 to the target angle W12 (S36).

The working machine 1 controls the prime mover 4, a traveling pump (first traveling pump 53L, second traveling pump 53R), a traveling motor (first traveling motor 36L, second traveling motor 36R), a traveling switching valve 34, and a traveling switching valve 34. A device 60 is provided, and the control device 60 reduces the swash plate angle of the traveling pump when switching from the second state to the first state. According to this, it is possible to reduce the shock of shifting when the speed of the working machine 1 is reduced (when switching from the second state to the first state).

When the control device 60 acquires the command to be in the first state by the changeover switch 61, after lowering the swash plate angle of the traveling pump from the target angle which is the swash plate angle set by the operating device 154, The traveling switching valve 34 is switched to the first state. According to this, since the actual angle is lowered from the target angle set by the operating device 154 before the deceleration of the working machine 1, the flow rate of the hydraulic oil discharged from the traveling pump is temporarily lowered during the deceleration. This allows the shift shock to be reduced.

The control device 60 restores the swash plate angle of the traveling pump at least after switching the traveling switching valve 34 to the first state. According to this, after the actual angle is lowered in order to reduce the shift shock, the actual angle can be brought to the state before deceleration as soon as possible.
The control device 60 makes the return time T32 for returning the swash plate angle shorter than the reduction time T31 for lowering the swash plate angle of the traveling pump. According to this, after the shift shock is reduced, the shift shock at the time of deceleration can be reduced as much as possible in the situation where the actual angle is returned as soon as possible before deceleration.

By the way, when the changeover switch 61 increases the speed from the first speed to the second speed or decelerates from the second speed to the first speed, the control device 60 switches the traveling changeover valve 34 from the command of the changeover switch 61. The switching time up to is different between speeding up and decelerating.
Specifically, as shown in FIG. 2A, the switching time from the speed-up command issued by the changeover switch 61 to the switching of the traveling switching valve 34 from the first state to the second state is shown in “Z10”, FIG. 2B. As described above, when the switching time from the deceleration command issued by the changeover switch 61 to the switching of the traveling switching valve 34 from the second state to the first state is set to "Z11", the switching time Z10 at the time of the speed increase command is decelerated. It is shorter than the switching time Z11 at the time of command (Z10 <Z11).

Further, as shown in FIG. 4A, the switching time from the speed-up command issued by the changeover switch 61 to the switching of the traveling switching valve 34 from the first state to the second state is “Z12”, as shown in FIG. 4B. When the switching time from issuing a command by the changeover switch 61 to switching the traveling switching valve 34 from the second state to the first state is set to "Z13", the switching time Z12 is shorter than the switching time Z13 (Z12 <Z13). ..

That is, in the control device 60, the switching time Z11 and Z13 from the operation of the changeover switch 61 to the switching of the traveling changeover valve 34 during deceleration is from the operation of the changeover switch 61 to the switching of the traveling changeover valve 34 during speed increase. The switching time is set longer than Z10 and Z12.
Further, in the above-described embodiment, as shown in FIGS. 2A and 2B, the rotation speed of the prime mover is reduced during speed increase and deceleration, and as shown in FIGS. However, the prime mover rotation speed and the swash plate angle may be combined and applied. For example, as shown in FIG. 2B, the control device 60 reduces the engine speed during deceleration, while lowering the swash plate angle during speed increase, as shown in FIG. 4A.

In the above-described embodiment, the control device 60 makes the reduction amounts ΔD1 and D2 of the prime mover rotation speed variable according to the traveling speed at the time of the shift command. Here, when the slopes K1 and K2 of the decrease in the prime mover rotation speed are kept constant, and when the reduction amounts ΔD1 and D2 are large, the decrease in the prime mover rotation speed is started until the predetermined rotation speeds W3 and W4 are reached. When the time (decrease time T1 and T11) is long and the reduction amounts ΔD1 and D2 are small, the reduction times T1 and T11 become long. The control device 60 sets the switching times Z10, Z11, Z12, and Z13 according to the lengths of the reduction times T1 and T11. When the reduction amounts ΔD1 and D2 are large and the reduction times T1 and T11 are long, the switching time is long. When Z10, Z11, Z12, Z13 are long, the reduction amounts ΔD1 and D2 are small, and the reduction times T1 and T11 are short, the switching times Z10, Z11, Z12 and Z13 are shortened. That is, the control device 60 sets the switching times Z10, Z11, Z12, and Z13 according to the traveling speed at the time of the shift command.

The control device 60 sets the switching time switching times Z10, Z11, Z12, and Z13 from the acquisition of the shift command to the switching of the traveling switching valve 34 differently between the speed increase and the deceleration. According to this, in a situation where the shift shock is reduced by lowering the engine speed, it is easy to match the feeling of the operator (operator) at the time of speed increase and the switching between the traveling switching valve 34, and at the time of deceleration. Also, it is easy to match the feeling of the operator with the switching between the traveling switching valve 34, and the operability can be improved.

The control device 60 sets the switching times Z10, Z11, Z12, and Z13 according to the traveling speed detected by the traveling detection device 67. According to this, since the timing of turning off at the time of shifting can be changed according to the traveling speed, the shifting shock can be further reduced.
The control device 60 makes the switching times Z11 and Z13 during deceleration longer than the switching times Z10 and Z12 during speeding up. According to this, the shift shock at the time of deceleration and the shift shock at the time of speed increase can be made substantially the same.

By the way, in the above-described embodiment, the swash plate angle is changed by the regulator 155, but the swash plate angle may be changed by another method. For example, as shown in FIG. 7, the discharge oil passage 40 is branched in the middle portion, and the proportional valve 69 is connected to the section 40a which is the discharge oil passage 40 after the branch and reaches the operating device 54. .. The proportional valve 69 is an electromagnetic proportional valve, and its opening degree can be changed by the control of the control device 60.

In a situation where the operation lever 59 of the operation device 54 has a full stroke, that is, the operation valves 55 (55A, 55B, 55C, 55D) are substantially fully opened, the control device 60 is changed from the first speed state to the second speed state by the changeover switch 61. When the command is obtained, the opening degree of the proportional valve 69 is made smaller than the opening degree when the changeover switch 61 is operated, so that the primary pressure of the hydraulic oil toward the operating valve 55 is lowered, and as in FIG. 4A, The swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) is lowered from the present. After the swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) decreases, the control device 60 switches the traveling switching valve 34 to the second state, and after switching to the second state, the proportional valve. The opening degree of 69 is restored.

Further, in a situation where the operation lever 59 of the operation device 54 has a full stroke, when the control device 60 acquires a command from the second speed state to the first speed state by the changeover switch 61, the opening degree of the proportional valve 69 is changed. By making it smaller than the opening degree during operation of 61, the primary pressure of the hydraulic oil toward the operating valve 55 is lowered, and the traveling pumps (first traveling pump 53L, second traveling pump 53R) are similarly described in FIG. 4B. Decrease the swash plate angle from the present. After the swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) decreases, the control device 60 switches the traveling switching valve 34 to the first state, and after switching to the first state, the proportional valve. The opening degree of 69 is restored. Whether or not the operation lever 59 has a full stroke can be grasped by the amount of operation detected by the operation detection device (sensor) 82.

That is, as shown in FIG. 7, the swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) is also increased or decelerated by the proportional valve 69 provided in the discharge oil passage 40 (40a). Can be reduced.
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.

In the above-described embodiment, the switching unit is composed of a changeover switch 61 that can be manually operated by an operator or the like, but it may be built in the control device 60. When built in the control device 60, the switching unit is composed of a program, electrical, and electronic components (electronic / electronic circuits) stored in the control device 60. In this case, the switching unit of the control device 60 determines whether to switch between the 1st speed state and the 2nd speed state based on the detection information from various detection devices provided in the work machine, for example, the sensor, and based on the judgment result. , A control signal is output to the traveling switching valve 34. The traveling switching valve 34 switches to the 1st speed state when the control signal in the 1st speed state is acquired, and switches to the 2nd speed state when the control signal in the 2nd speed state is acquired.

The travel switching valve 34 is a valve that can switch between a first state in which the travel motors (first travel motor 36L, second travel motor 36R) are set to the first speed and a second state in which the travel motors are set to the second speed. Often, it may be a proportional valve different from the directional control valve.
The traveling motor may be a motor having neutrality between the first speed and the second speed.

The traveling motor (first traveling motor 36L, second traveling motor 36R) may be an axial piston motor or a radial piston motor. When the traveling motor is a radial piston motor, it is possible to switch to the first speed by increasing the motor capacity, and it is possible to switch to the second speed by reducing the motor capacity.
Since the traveling speed changes depending on the operation of the traveling lever 59, the traveling detection device 67 may be a device that detects the traveling speed based on the operating amount (operating angle) and the operating position of the operating lever 59. As described above, since the second speed (second state) may be faster than the first speed (first state), the work machine is not limited to two speeds, and may have multiple speeds (multiple stages). Even if there is, it can be applied.

1 Work machine 2 Aircraft 32 Motor 34 Travel switching valve 36L 1st travel motor 36R 2nd travel motor 53L 1st travel pump 53R 2nd travel pump 60 Control device 65 Accelerator 67 Travel detection device

Claims (8)

The prime mover and
A traveling pump that can change the flow rate of hydraulic oil to be discharged according to the angle of the swash plate,
A traveling motor that can rotate by the hydraulic oil discharged by the traveling pump and can switch between a first speed and a second speed whose rotation speed is higher than the first speed.
A traveling switching valve capable of switching between a first state in which the rotation speed of the traveling motor is set to the first speed and a second state in which the rotation speed of the traveling motor is set to the second speed.
A control device that reduces the angle of the swash plate of the traveling pump when switching from the second state to the first state.
A working machine equipped with. A switching unit that gives a command to switch between the first state and the second state,
An operating device that can change the angle of the swash plate of the traveling pump,
With
When the switching unit issues a command to bring the first state to the control device, the control device sets the angle of the swash plate of the traveling pump to be larger than the target angle which is the angle of the swash plate set by the operating device. The working machine according to claim 1, wherein the traveling switching valve is switched to the first state after being lowered. The working machine according to claim 2, wherein the control device returns the angle of the swash plate of the traveling pump at least after switching the traveling switching valve to the first state. The working machine according to claim 3, wherein the control device makes the return time for returning the angle of the swash plate shorter than the lowering time for lowering the swash plate of the traveling pump. An airframe provided with the prime mover, a traveling pump and a traveling motor, and
A travel detection device that can detect the travel speed of the aircraft, and
With
The working machine according to any one of claims 1 to 4, wherein the control device sets an amount of decrease in the angle of the swash plate according to the traveling speed detected by the traveling detection device. It is equipped with an airframe provided with the prime mover, a traveling pump and a traveling motor.
The working machine according to any one of claims 1 to 5, wherein the control device reduces the angle of the swash plate when the machine body is in a traveling state. With the aircraft
The first traveling device provided on the left side of the aircraft and
The second traveling device provided on the right side of the aircraft and
With
The traveling motor is a first traveling motor that transmits traveling power to the first traveling device and a second traveling motor that transmits traveling power to the second traveling device.
The traveling pump can operate the first traveling motor and the second traveling motor.
The working machine according to any one of claims 1 to 4, wherein the traveling switching valve can switch the first traveling motor and the second traveling motor between the first speed and the second speed. The working machine according to any one of claims 1 to 7, wherein the switching unit is a switching switch that outputs a command to switch between the first state and the second state to the control device.

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