JP7155038B2 - work machine - Google Patents

Description

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

2. Description of the Related Art Conventionally, Patent Document 1 discloses a technique for decelerating and accelerating a working machine. The hydraulic system of the work machine disclosed in Patent Document 1 includes a hydraulic pump that discharges hydraulic oil, a hydraulic switching valve that can be switched between a plurality of switching positions according to the pressure of the hydraulic oil, and a speed control valve that changes speed according to the switching position of the hydraulic switching valve. with variable travel hydraulics.

JP 2017-179922 A

In the work machine disclosed in 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 shift shock when accelerating or decelerating the work machine. However, in Patent Document 1, a bleed oil passage must be provided in order to reduce shift shock, resulting in an increase in the number of parts. In addition, a travel motor that does not have a neutral is required to sufficiently reduce shift shock.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a working machine capable of easily reducing shift shock.

The technical measures taken by the present invention to solve the technical problems are as follows.
The work machine includes a prime mover, a traveling pump capable of changing the flow rate of hydraulic oil discharged according to the angle of the swash plate, and being rotatable by the hydraulic oil discharged by the traveling pump, and having a rotation speed of a first speed. a travel motor switchable to a second speed higher than the first speed; a first state in which the rotation speed of the travel motor is set to the first speed; and a rotation speed of the travel motor to the second speed. a travel switching valve that can be switched to a second state; a controller that reduces the angle of the swash plate of the travel pump when switching from the second state to the first state ; An airframe provided with a travel motor and a travel detection device capable of detecting travel speed of the airframe , wherein the control device adjusts the angle of the swash plate according to the travel speed detected by the travel detection device. set the amount of decrease in

The work machine includes a switching unit for issuing a command to switch between the first state and the second state, and an operating device capable of changing an angle of a swash plate of the traveling pump, wherein the control device comprises the switching unit. command to switch to the first state, after the angle of the swash plate of the traveling pump is reduced below the target angle, which is the angle of the swash plate set by the operating device, the traveling switching Switching the valve 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 restoring the angle of the swash plate shorter than the lowering time for lowering the swash plate of the traveling pump .

The work 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 work 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 a second travel motor that transmits travel power to the second travel device, and the travel pump is capable of operating the first travel motor and the second travel motor. The travel switching valve is capable of switching the first travel motor and the second travel motor between the first speed and the second speed.

The switching unit is a changeover 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 showing a hydraulic system (hydraulic circuit) of a work machine in a 1st embodiment. FIG. 4 is a diagram showing the relationship between the number of revolutions of the prime mover and the switching of the travel motor when the travel motor is accelerated; FIG. 10 is a diagram showing the relationship between the number of rotations of the driving motor and the switching of the driving motor when the driving motor is decelerated; FIG. 10 is a diagram showing a first operation flow of the control device when speeding up the travel motor; FIG. 10 is a diagram showing a second operation flow of the control device when the traveling motor is decelerated; FIG. 5 is a diagram showing a relationship between a swash plate angle of a traveling pump and switching of the traveling motor when the speed of the traveling motor is increased. FIG. 10 is a diagram showing the relationship between the swash plate angle of the travel pump and the switching of the travel motor when the travel motor is decelerated; FIG. 10 is a diagram showing a third operation flow of the control device when speeding up the travel motor; FIG. 10 is a diagram showing a fourth operation flow of the control device when the traveling motor is decelerated; It is a figure which shows the hydraulic system (hydraulic circuit) of the working machine in 2nd Embodiment. It is a figure which shows the modification of the hydraulic system (hydraulic circuit) of a working machine. 4 is a table showing the relationship between the actual engine speed W1, the driving pilot pressure, and the reduction amount ΔD1 of the engine speed; 8B is the graph of FIG. 8A; 4 is a table showing the relationship between the travel pilot pressure and the amount of decrease in the travel pilot pressure (the amount of decrease ΔD2). 9B is the graph of FIG. 9A; 1 is a side view showing a track loader that is an example of a working machine; FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a hydraulic system for a working machine according to the present invention and a working machine equipped with this hydraulic system will now be described with reference to the drawings as appropriate.
[First embodiment]
FIG. 10 shows a side view of a working machine according to the invention. FIG. 10 shows a compact track loader as an example of the work machine. However, the work machine according to the present invention is not limited to a compact track loader, and may be other types of loader work machine such as a skid steer loader. Also, a work machine other than a loader work machine may be used.

As shown in FIG. 10 , work machine 1 includes machine body 2 , cabin 3 , work device 4 , and travel device 5 . In the embodiment of the present invention, the front side of the driver (the left side in FIG. 10) sitting in the driver's seat 8 of the working machine 1 is the front side, the rear side of the driver (the right side in FIG. 10) is the rear side, and the left side of the driver 10) is the left side, and the driver's right side (back side in FIG. 10) is the right side. Also, 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 body 2 to the right or left will be described as the outward direction of the body. In other words, the outer side of the fuselage is the width direction of the fuselage and the direction away from the fuselage 2 . The direction opposite to the outer side of the fuselage will be described as the inner side of the fuselage. In other words, the inner side of the body is the width direction of the body and the direction toward the body 2 .

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

The booms 10 are provided on the right and left sides 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 (front end) of the boom 10 so as to be vertically swingable. The lift link 12 and the control link 13 support the base (rear portion) of the boom 10 so that the boom 10 can swing vertically. The boom cylinder 14 raises and lowers the boom 10 by extending and contracting. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

The front portions of the left and right booms 10 are connected to each other by a connecting pipe of an irregular shape. The bases (rear portions) of the booms 10 are connected to each other by circular connecting pipes.
A lift link 12, a control link 13 and a boom cylinder 14 are provided on the left and right sides of the fuselage 2 corresponding to the left and right booms 10, respectively.
A lift link 12 is provided longitudinally at the rear of the base of each boom 10 . An upper portion (one end side) of the lift link 12 is pivotally supported toward the rear portion of the base of each boom 10 via a pivot shaft 16 (first pivot shaft) so as to be rotatable about a horizontal axis. A lower portion (the other end side) of the lift link 12 is pivotally supported toward the rear portion of the fuselage 2 via a pivot shaft 17 (second pivot shaft) so as to be rotatable about the horizontal axis. The second pivot shaft 17 is provided below the first pivot shaft 16 .

An 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 the base of each boom 10 and is provided at the front of the base. A lower portion of the boom cylinder 14 is pivotally supported around a horizontal axis via a pivot shaft 19 (fourth pivot shaft). The fourth pivot shaft 19 is provided near the lower portion of the rear portion of the body 2 and below the third pivot shaft 18 .

The control link 13 is provided forward 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 provided on the body 2 at a position corresponding to the front of the lift link 12 . The other end of the control link 13 is rotatably supported around the horizontal axis via a pivot shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is provided on the boom 10 in front of the second pivot shaft 17 and above the second pivot shaft 17 .

By extending 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 end of each boom 10 is moved. rises and falls. 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.

Instead of the bucket 11, another working tool can be attached to the front portion of the boom 10. - 特許庁Other work tools include attachments (preliminary attachments) such as hydraulic crushers, hydraulic breakers, angle blooms, earth augers, pallet forks, sweepers, mowers, and snow blowers.
A connection member 50 is provided on the front portion of the boom 10 on the left side. The connection member 50 is a device that connects the hydraulic equipment mounted on the spare attachment and the first pipe member such as a pipe provided on the boom 10 . Specifically, a first pipe member can be connected to one end of the connection member 50, and a second pipe member connected to the hydraulic equipment of the auxiliary attachment can be connected to the other end. As a result, hydraulic fluid flowing through the first pipe member passes through the second pipe member and is supplied to the hydraulic equipment.

The bucket cylinder 15 is arranged near the front portion of each boom 10 . By extending and contracting the bucket cylinder 15, the bucket 11 is swung.
The left and right traveling devices (first traveling device, second traveling device) 5 employ crawler type (including semi-crawler type) traveling devices in this embodiment. A wheel-type traveling device having front and rear wheels may be employed.

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, prime mover 32 is a diesel engine, but is not so limited.
Next, the hydraulic system of the working machine will be described.
As shown in FIG. 1 , the hydraulic system of the work machine can drive the traveling device 5 . The hydraulic system of the working machine includes a first travel pump 53L, a second travel pump 53R, a first travel motor 36L, and a second travel 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 displacement axial pumps driven by the power of the prime mover 32 . The first traveling pump 53L and the second traveling pump 53R each have a forward pressure receiving portion 53a and a reverse pressure receiving portion 53b on which pilot pressure acts. The angle of the plate is changed. By changing the angle of the swash plate, it is possible to change the output (discharge amount of hydraulic oil) of the first traveling pump 53L and the second traveling pump 53R and the discharge direction of the hydraulic oil.

The first travel pump 53L and the first travel motor 36L are connected by a circulation oil passage 57h, and hydraulic fluid discharged from the first travel pump 53L is supplied to the first travel motor 36L. The second travel pump 53R and the second travel motor 36R are connected by a circulation oil passage 57i, and hydraulic oil discharged from the second travel pump 53R is supplied to the second travel motor 36R.
The first travel motor 36L is a motor that transmits power to the drive shaft of the travel device 5 provided on the left side of the body 2 . The first traveling motor 36L can be rotated by hydraulic oil discharged from the first traveling pump 53L, and can change the rotation speed (number of rotations) according to the flow rate of the hydraulic oil. A swash plate switching cylinder 37L is connected to the first travel motor 36L, and the rotation speed (number of rotations) of the first travel motor 36L is changed by extending or 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 travel motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is extended, the first travel motor 36L is is set to a high speed (second speed). That is, the rotation speed of the first travel motor 36L can be changed between a first speed on the low speed side and a second speed on the high speed side.

The second travel motor 36R is a motor that transmits power to the drive shaft of the travel device 5 provided on the right side of the body 2 . The second traveling motor 36R can be rotated by hydraulic oil discharged from the second traveling pump 53R, and can change the rotation speed (number of rotations) according to the flow rate of the hydraulic oil. A swash plate switching cylinder 37R is connected to the second travel motor 36R, and the rotational speed (number of rotations) of the second travel motor 36R is changed by extending or 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 travel motor 36R is set at a low speed (first speed), and when the swash plate switching cylinder 37R is extended, the second travel motor 36R is rotated. is set to a high speed (second speed). In other words, the rotation speed of the second traveling motor 36R can be changed between a first speed on the low speed side and a second speed on the high speed side.

As shown in FIG. 1 , the hydraulic system of the working machine includes a travel switching valve 34 . The travel switching valve 34 switches the rotation speed (number of rotations) of the travel motors (first travel motor 36L, second travel motor 36R) between a first state and a second state. It is possible. The traveling switching valve 34 has first switching valves 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 travel motor 36L via an oil passage and switches between a first position 71L1 and a second position 71L2. The first switching valve 71L contracts the swash plate switching cylinder 37L when it is at the first position 71L1, and extends the swash plate switching cylinder 37L when it is at 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 travel motor 36R via an oil passage and switches between a first position 71R1 and a second position 71R2. The second switching valve 71R contracts the swash plate switching cylinder 37R when it is at the first position 71R1, and extends the swash plate switching cylinder 37R when it is at the second position 71R2.
The second switching valve 72 is an electromagnetic 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 a first position 72a and a 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 at the first position 72a, and switches the first switching valve 71L and the second switching valve 71R when it is at 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 at the first position 72a, the first switching valve 71L is at the first position 71L1, and the first switching valve 71R is at the first position 71R1, the travel switching valve 34 is in the first state, The rotational speeds of the travel motors (first travel motor 36L, second travel motor 36R) are set to the first speed. When the second switching valve 72 is at the second position 72b, the first switching valve 71L is at the second position 71L2, and the second switching valve 71R is at the second position 71R2, the traveling switching valve 34 is in the second state, and the traveling motor The rotational speeds of (first travel motor 36L, second travel motor 36R) are set to the second speed.

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

The control device 60 is composed of semiconductors such as a CPU and an MPU, electrical and electronic circuits, and the like. The control device 60 switches the traveling switching valve 34 based on the switching operation of the switching switch 61 . The changeover switch 61 is a push switch. For example, when the travel motor is pressed at the first speed, the changeover switch 61 outputs a command to set the travel motor to the second speed (command to set the travel switching valve 34 to the second state) to the control device 60 . be done. When the changeover switch 61 is pressed while the travel motor is in the second speed state, a command to set the travel motor to the first speed (command to set the travel switching valve 34 to the first state) is output to the control device 60 . . The change-over switch 61 may be a push switch that can be held ON/OFF. When the switch 61 is OFF, a command to hold the traveling motor at the first speed is output to the control device 60, and the switch is ON. If so, a command is output to controller 60 to hold the traction motor at the second speed.

When the control device 60 acquires a command to put the travel switching valve 34 in the first state, it demagnetizes the solenoid of the second switching valve 72 to put the travel switching valve 34 in the first state. In addition, when the control device 60 acquires a command to put the travel switching valve 34 in the second state, the controller 60 energizes the solenoid of the second switching valve 72 to put the travel switching valve 34 in the second state.
The hydraulic system of the working machine includes a first hydraulic pump P1, a second hydraulic pump P2, and an operating device 54. As shown in FIG. The first hydraulic pump P1 is a pump driven by the power of the prime mover 32, and is configured by a constant displacement gear pump. The first hydraulic pump P<b>1 can discharge hydraulic oil stored in the tank 22 . In particular, the first hydraulic pump P1 discharges hydraulic oil that is mainly used for control. For convenience of explanation, the tank 22 that stores hydraulic oil may be referred to as a hydraulic oil tank. Among the hydraulic fluid discharged from the first hydraulic pump P1, the hydraulic fluid used for control is sometimes called pilot oil, and the pressure of the pilot oil is sometimes called pilot pressure.

The second hydraulic pump P2 is a pump that is driven by the power of the prime mover 32 and is composed of a constant displacement gear pump. The second hydraulic pump P2 can discharge hydraulic oil stored in the tank 22, and supplies hydraulic oil to, for example, a work system oil passage. 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. do.

The operating device 54 is a device for operating the traveling pumps (the first traveling pump 53L and the second traveling pump 53R), and can change the angle of the swash plate (swash plate angle) of the traveling pump. The operating device 54 includes an operating lever 59 and a plurality of operating valves 55 .
The operation lever 59 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 to the right and left from the neutral position N, and can be operated forward and backward from the neutral position N. As shown in FIG. In other words, the operating lever 59 can swing in at least four directions with the neutral position N as a reference. For convenience of explanation, the front and rear directions, that is, the front and rear directions are referred to as the first direction. Also, the left and right bidirectional directions, that is, the left and right direction (body width direction) may be referred to as the second direction.

Moreover, the plurality of operation valves 55 are operated by a single operating lever 59 in common. A plurality of operation valves 55 are operated based on the swinging motion of the operation 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 P<b>1 can be supplied via the discharge oil passage 40 . The plurality of operation valves 55 are an operation valve 55A, an operation valve 55B, an operation valve 55C and an operation valve 55D.

When the operation lever 59 is swung forward (one side) in the front-rear direction (first direction) (when the front operation is performed), the operation valve 55A outputs according to the operation amount (operation) of the front operation. Oil pressure changes. The operation valve 55B is operated to output in accordance with the operation amount (operation) of the post-operation when the operation lever 59 is swung backward (the other direction) in the front-rear direction (first direction) (in the case of post-operation). Oil pressure changes. In the left-right direction (second direction), when the operation lever 59 is swung to the right (one side) (right operation), the operation valve 55C outputs according to the amount of right operation (operation). Hydraulic oil pressure changes. When the operation lever 59 is swung to the left (the other direction) in the left-right direction (second direction) (left operation), the operation valve 55D outputs according to the operation amount (operation) of the left operation. The pressure of the operating hydraulic oil changes.

The plurality of operation 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 pumps (the first traveling pump 53L, the second traveling pump 53R) have hydraulic pressure that can be operated by hydraulic fluid output from the operation valves 55 (the operation valves 55A, 55B, 55C, and 55D). Equipment.
The traveling oil passage 45 has a first traveling oil passage 45a, a second traveling oil passage 45b, a third traveling oil passage 45c, a fourth traveling oil passage 45d, and a fifth traveling oil passage 45e. The first traveling oil passage 45a is an oil passage connected to the forward pressure receiving portion 53a of the traveling pump 53L. The second travel oil passage 45b is an oil passage connected to the reverse pressure receiving portion 53b of the travel pump 53L. The third traveling oil passage 45c is an oil passage connected to the forward pressure receiving portion 53a of the traveling pump 53R. The fourth travel oil passage 45d is an oil passage connected to the reverse pressure receiving portion 53b of the travel pump 53R. The fifth travel oil passage 45e is an oil passage that connects the operation valve 55, the first travel oil passage 45a, the second travel oil passage 45b, the third travel oil passage 45c, and the fourth travel oil passage 45d.

When the operating lever 59 is swung forward (in the direction of arrow A1 in FIG. 1), the operating valve 55A is operated and pilot pressure is output from the operating valve 55A. This pilot pressure acts on the pressure receiving portion 53a of the first traveling pump 53L through the first traveling oil passage 45a and acts on the pressure receiving portion 53a of the second traveling pump 53R through the third traveling oil passage 45c. As a result, the swash plate angles of the first travel pump 53L and the second travel pump 53R are changed, the first travel motor 36L and the second travel motor 36R rotate forward (rotate forward), and the work implement 1 travels straight forward. .

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

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

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

Further, when the operating lever 59 is swung in an oblique direction, the rotational direction and rotational speed of the first travel motor 36L and the second travel motor 36R are changed by the differential pressure between the pilot pressures acting on the pressure receiving portions 53a and 53b. It is determined, and the work implement 1 turns right or left while moving forward or backward.
That is, when the operating lever 59 is swung diagonally forward left, the work machine 1 moves forward and turns left at a speed corresponding to the swing angle of the operating lever 59, and when the operating lever 59 is swung diagonally forward right, the working machine 1 turns leftward. The work machine 1 moves forward and turns to the right at a speed corresponding to the swing angle of the operating lever 59, and when the operating lever 59 is swung obliquely rearward to the left, the work machine 1 moves at a speed corresponding to the swing angle of the operating lever 59. When the operating lever 59 is swung obliquely rearward to the right, the work machine 1 travels backward at a speed corresponding to the swing angle of the operating lever 59 and rotates to the right while moving backward.

The control device 60 is connected to an accelerator 65 for setting the engine speed. The accelerator 65 is provided near the driver's seat 8 . The accelerator 65 is a rockably supported accelerator lever, a rockably supported accelerator pedal, a rotatably supported accelerator volume, a slidably supported accelerator slider, or the like. In addition, the accelerator 65 is not limited to the example mentioned above. Also, the control device 60 is connected to a rotation detection device 66 that detects the number of revolutions of the prime mover. The rotation detection device 66 allows the control device 60 to grasp the actual motor rotation speed (actual rotation speed) of the motor 32 .

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

The control device 60 reduces the number of revolutions of the prime mover based on the running state of the working machine (machine body 2). For example, when the work machine (machine body 2) is running as the traveling state at the time of acceleration, the control device 60 reduces the number of rotations of the prime mover, and determines that the work machine (machine body 2) is stopped as the traveling state. If so, do not reduce the engine speed.
FIG. 2A is a diagram showing the relationship between the number of rotations (target number of rotations, actual number of rotations) of the prime mover when the traveling motor is accelerated from the first speed to the second speed, and switching of the traveling motor.

As shown in FIG. 2A, at time point Q1, control device 60 operates changeover switch (changeover SW) 61, and control device 60 shifts from a first state (first speed) to a second state (second speed). Suppose that a speed-up command (2nd speed command) to be obtained. When the control device 60 acquires the 2nd speed command, the control device 60 reduces the actual rotation speed W1 to a predetermined rotation speed W3 that is lower than the target rotation speed W2 set by the accelerator 65 . The predetermined number of revolutions W3 is a number of revolutions that reduces a shift shock when switching from the first speed to the second speed, and is, for example, a value obtained by subtracting the amount of decrease ΔD1 from the actual number of revolutions W1.

The control device 60 sets the decrease amount ΔD1 according to the running speed of the working machine (body 2), which is one of running states. Specifically, the control device 60 is connected to a running detection device 67 that detects the running speed as the running state. The traveling detection device 67 detects, for example, the pressure (pilot pressure) of hydraulic oil (pilot oil) output from the operation valves 55 (the operation valves 55A, 55B, 55C, and 55D). It is a device that converts pilot pressure into running speed. For example, when the pilot pressure of the travel oil passage 45 is high, the travel speed is detected to be high, and when the pilot pressure is low, the travel speed is detected to be low. Note that the travel detection device 67 detects the travel speed from the pilot pressure of the travel oil passage 45, but instead of this, it detects the rotation speed of the rotation shaft of the travel motor and travels at the detected rotation speed. Any device that converts to speed may be used as long as the traveling speed can be detected.
That is, when switching to acceleration, the control device 60 sets a reduction amount ΔD1 corresponding to the traveling speed detected by the traveling detection device 67, and reduces the engine speed corresponding to the set reduction amount ΔD1.

As shown in FIG. 8A, the control device 60 stores reduction amount calculation data indicating the relationship between the actual rotation speed W1, the pilot pressure (driving pilot pressure) of the traveling oil passage 45, and the reduction amount ΔD1. FIG. 8B is a graph of FIG. 8A. Note that the reduction amount calculation data in FIGS. 8A and 8B is an example and is not limited.
For example, as shown in FIG. 8A, when the control device 60 acquires the 2nd speed command, the reduction amount ΔD1 is set to 500 rpm when the actual rotation speed W1 is 3000 rpm and the running pilot pressure is 1.5 MPa. As shown in FIG. 8A, the control device 60 sets the lower limit of the engine speed so that the engine speed does not fall below the minimum engine speed when the engine speed is reduced. In reducing the engine speed, the control device 60 keeps the slope K1 (the slope of the decrease time T1) for decreasing the engine speed constant even when the amount of decrease ΔD1 is different.

When the actual rotation speed W1 reaches the predetermined rotation speed W3 at time 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 during the decrease time T1 for decreasing the actual rotation speed W1 to the predetermined rotation speed W3. Here, the control device 60 makes 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 reduction time T1. That is, the control device 60 makes the reduction speed for decreasing the actual rotation speed W1 to the predetermined rotation speed W3 faster than the return speed for returning the actual rotation speed W1 from the predetermined rotation speed W3 to the target rotation speed W2.

Further, the control device 60 outputs a signal to excite the solenoid of the travel 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 the control flow of the control device 60 when changing the rotation speed of the travel motor from the first speed to the second speed. Note that the work machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the switch 61 has been switched from the first speed to the second speed (S1). When the selector switch 61 is not switched to the second speed, that is, when the first speed is maintained (S1, No), the control device 60 changes the actual rotation speed W1 to the target rotation speed based on the operation of the accelerator 65. The number W2 is set (S2). When the change-over switch 61 is switched from the first speed to the second speed (S1, Yes), the control device 60 decreases the actual rotation speed W1 toward a predetermined rotation speed W3 lower than the target rotation speed W2 (S3 ). Before the actual rotation speed W1 reaches the predetermined rotation speed W3, the control device 60 switches the travel switching valve 34 from the first state (first speed) to the second state (second speed) (S4). ). The control device 60 determines whether or not the actual number of revolutions W1 has reached the predetermined number of revolutions W3 (S5). The target rotation speed W2 is restored (S6). When the actual rotation speed W1 has not reached the predetermined rotation speed W3 (S5, No), the control device 60 decreases the actual rotation speed W1 toward the predetermined rotation speed W3 (S3), and the traveling switching valve 34 is closed. If the first state (first speed) has already been switched to the second state (second speed) (if the processing of S4 has already been performed), skip the processing of S4 and proceed to the processing of S5. do. Further, in the control device 60, the process of decreasing the actual rotation speed W1 toward the predetermined rotation speed W3 and the process of switching the travel switching valve 34 may be performed separately in parallel.

Now, in the above-described embodiment, when the speed of the work implement 1 is increased from the first speed to the second speed, the rotation speed of the prime mover is reduced. In some cases, the engine speed may be reduced.
When switching the traveling switching valve 34 from the second state (second speed) to the first state (first speed), that is, when switching the rotation speed of the traveling motor from the second speed to the first speed to reduce the engine speed. For example, during deceleration, if the working machine (body 2) is running as the running state, the control device 60 reduces the number of rotations of the prime mover, and the working machine (body 2) is stopped as the running state. In this case, do not reduce the engine speed.

FIG. 2B is a diagram showing the relationship between the number of rotations (target number of rotations, actual number of rotations) of the prime mover when the traveling motor is decelerated from the first speed to the second speed, and switching of the traveling motor.
As shown in FIG. 2B, at time point Q11, control device 60 operates changeover switch (changeover SW) 61, and control device 60 switches from the second state (second speed) to the first state (first speed). Suppose that a deceleration command (1st speed command) to be obtained. When the control device 60 acquires the 1st speed command, the control device 60 reduces the actual rotation speed W1 to a predetermined rotation speed W4 that is lower than the target rotation speed W2 set by the accelerator 65 . The predetermined number of revolutions W4 is a number of revolutions that reduces a shift shock when switching from the second speed to the first speed, and is set, for example, by the amount of decrease ΔD1 from the target number of revolutions W2. The setting of the amount of decrease ΔD1 is the same as in the above-described embodiment, and the control device 60 sets the amount of decrease ΔD1 corresponding to the running speed detected by the running detection device 67 when switching to deceleration. The motor rotation speed is decreased corresponding to the amount of decrease ΔD1. In reducing the engine speed, the control device 60 keeps the slope K2 for decreasing the engine speed (the slope of the decrease time T11) constant even when the amount of decrease 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 during the decrease time T11 for decreasing the actual rotation speed W1 to the predetermined rotation speed W4. Here, the control device 60 makes the recovery 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 for decreasing the actual rotation speed W1 to the predetermined rotation speed W3 slower than the return speed for returning the actual rotation speed W1 from the predetermined rotation speed W3 to the target rotation speed W2.

Further, the control device 60 outputs a signal for demagnetizing the solenoid of the travel switching valve 34 before returning the actual rotation speed W1 from the predetermined rotation speed W4 to the target rotation speed W2. 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 the control flow of the control device 60 when changing the rotation speed of the travel motor from the second speed to the first speed. Note that the work machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the switch 61 has been switched from the second speed to the first speed (S11). If the selector switch 61 is not switched to the first speed, that is, if the second speed is maintained (S11, No), the control device 60 changes the actual rotation speed W1 to the target rotation speed based on the operation of the accelerator 65. The number W2 is set (S12). When the change-over 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 travel switching valve 34 is switched from the second state (second speed) to the first state (first speed) (S15). The control device 60 restores the actual rotation speed W1 to the target rotation speed W2 (S16).

The work machine 1 includes a prime mover 32, travel pumps (first travel pump 53L, second travel pump 53R), travel motors (first travel motor 36L, second travel motor 36R), travel switching valve 34, control and a device 60, the control device 60, when switching to either acceleration for switching from the first state to the second state or deceleration for switching from the second state to the first state, based on the running state of the aircraft body 2 to reduce the engine speed. According to this, when the speed of the work implement 1 is increased or decelerated, since the number of revolutions of the prime mover is reduced in accordance with the running state, the shift shock can be reduced in accordance with the running state. can be reduced.

The control device 60 reduces the motor rotation speed when the machine body 2 is running as the running state, and does not reduce the motor rotation speed when the machine body 2 is stopped as the running state. According to this, it is possible to further reduce the shock caused by gear shifting while the machine body 2 is running.
The control device 60 responds to the running speed detected by the running detection device 67 when switching to either acceleration for switching from the first state to the second state or deceleration for switching from the second state to the first state. A reduction amount ΔD1 of the engine speed is set, and the engine rotation speed is reduced corresponding to the set reduction amount ΔD1. According to this, when the speed of the working machine 1 is increased or decelerated, the number of revolutions of the prime mover is reduced in accordance with the traveling speed, so that no matter what the traveling speed is. Also, it is possible to reduce the shift shock.

Further, when the switching unit (change-over switch 61) issues a gear shift command, the control device 60 reduces the engine rotation speed below the target engine rotation speed set by the accelerator 65, and then starts running. The switching valve 34 is switched between the first state and the second state according to the shift command. According to this, in order to lower the motor rotation speed below the target rotation speed set by the accelerator 65 before accelerating or decelerating the work implement 1, the running pump can temporarily reduce the flow rate of the hydraulic oil discharged from the engine, thereby reducing shift shock.

After switching the travel switching valve 34, the control device 60 restores the engine speed. According to this, after the engine speed is reduced in order to reduce the shift shock, the engine speed can be returned to the state before deceleration as soon as possible.
The control device 60 sets the recovery time T2 for restoring the motor revolution speed to be longer than the decrease time T1 for decreasing the motor revolution speed in the case of acceleration, and sets the return time T12 to be shorter than the decrease time T11 in the case of deceleration. do. According to this, after reducing the shift shock, it is possible to reduce the shift shock as much as possible in a situation where the engine speed is returned as quickly as possible before the shift.

[Second embodiment]
FIG. 6 shows the hydraulic system of the working machine in the second embodiment. In the second embodiment, not only the operating device 154 changes the swash plate angle of the traveling pumps (the first traveling pump 53L and the second traveling pump 53R), but also the control device 60 changes the swash plate angle of the traveling pumps. be able to. 6 shows traveling pumps (first traveling pump 53L, second traveling pump 53R), operation device 154 and control device 60, but other parts are the same as in FIG.

The operating device 154 is a joystick-type device that electrically changes the swash plate angle of the traveling pump. 82. When the operation lever 59 is operated rightward, leftward, forward, or backward, 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 swash plate angle. Change the plate angle. The traveling pumps (the first traveling pump 53L and the second traveling pump 53R) discharge a larger flow rate of hydraulic oil as the swash plate angle increases, and a smaller flow rate of the discharged hydraulic oil as the swash plate angle decreases. Become. An angle detection device 68 that detects the angle of the swash plate is also 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 operates the travel pumps (first travel pump 53L, The swash plate angle of the second traveling pump 53R) is lowered.
FIG. 4A is a diagram showing the relationship between the swash plate angle (target angle, actual angle) and switching of the travel motor when the travel motor is accelerated from the first speed to the second speed.

As shown in FIG. 4A, at time point Q21, the control device 60 operates the changeover switch (changeover valve) 61, and the control device 60 shifts from the first state (first speed) to the second state (second speed). Suppose that a command (2nd speed command) to set is acquired. When the control device 60 acquires the second speed command, the control device 60 changes the actual angle W11 of the traveling pumps (the first traveling pump 53L, the second traveling pump 53R) to the target swash plate angle set based on the operation amount of the operating device 154. It is lowered to a predetermined angle W13 that is lower than the angle (target angle) W12. The predetermined angle W13 is an angle that reduces a 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 drop amount calculation data indicating the relationship between the travel pilot pressure and the drop amount (drop amount ΔD2) of the travel pilot pressure. FIG. 9B is a graph of FIG. 9A. The decrease amount calculation data in 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.

9A and 9B show the amount of decrease in the travel pilot pressure, and there is a correlation between the amount of decrease in the travel pilot pressure and the amount of decrease ΔD2 in the swash plate angle. That is, since the swash plate angle is controlled by the travel pilot pressure, the higher the travel pilot pressure, the larger the swash plate angle, and the lower the travel pilot pressure, the smaller the swash plate angle.
For example, as shown in FIG. 9A, when the control device 60 acquires the 2nd gear 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 Set to 0.50 MPa. As shown in FIG. 9A, the controller 60 adjusts the swash plate angle (travel pilot pressure ) is set.

When actual angle W11 reaches predetermined angle W13 at time point Q22, controller 60 returns actual angle W11 to target angle W12. Alternatively, the control device 60 returns the actual angle W11 to the target angle W12 during the decrease time T21 for decreasing the actual angle W11 to the predetermined angle W13. Here, the control device 60 makes the return time T22 for returning the actual angle W11 from the predetermined angle W13 to the target angle W12 longer than the decrease 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 to excite the solenoid of the travel switching valve 34 at least during the decrease 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 the control flow of the control device 60 when changing the rotation speed of the travel motor from the first speed to the second speed in the second embodiment. Note that the work machine is not in a stopped state but in a running state.
The controller 60 determines whether or not the switch 61 has been switched from the first speed to the second speed (S21). If the selector switch 61 is not switched to the second speed, that is, if the first speed is maintained (S21, No), the control device 60 changes the actual angle W11 to the target angle based on the operation of the operating device 154. W12 is set (S22). When the change-over switch 61 is switched from the first speed to the second speed (S1, Yes), the control device 60 decreases the actual angle W11 toward a predetermined angle W13 lower than the target angle W12 (S23). The controller 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). (S26).

If the actual angle W11 has not reached the predetermined angle W13 (S25, No), the control device 60 reduces the actual angle W11 toward the predetermined angle W13 (S23), When the state (first speed) is switched to the second state (second speed) (when the processing of S24 has already been performed), the processing of S24 is skipped and the processing proceeds to S25. Further, in the control device 60, the process of decreasing the actual angle W11 toward the predetermined angle W13 and the process of switching the travel switching valve 34 may be processed separately in parallel.

The work machine 1 includes a prime mover 32, travel pumps (first travel pump 53L, second travel pump 53R), travel motors (first travel motor 36L, second travel motor 36R), travel switching valve 34, control a device 60, the controller 60 decreasing the swashplate angle of the travel pump when switching from the first state to the second state. According to this, it is possible to reduce the shift shock when increasing the speed of the work implement 1 (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. After the swash plate angle of the travel pump is lowered below the target angle, which is the plate angle, the travel switching valve 34 is switched to the second state. According to this, in order to make the actual angle lower than the target angle set by the operating device 154 before the speed increase of the work implement 1, the flow rate of the hydraulic oil discharged from the traveling pump is temporarily reduced during the speed increase. can be reduced, thereby reducing shift shock.

After switching the travel switching valve 34 to the second state, the controller 60 restores the swash plate angle of the travel pump. According to this, after the actual angle is decreased in order to reduce the shift shock, the actual angle can be returned to the state before speed increase as soon as possible.
The control device 60 makes the return time T22 for restoring the swash plate angle longer than the decrease time T21 for decreasing 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 a situation where the actual angle is returned as soon as possible before the speed increase.

The control device sets the amount of decrease in the swash plate angle according to the travel speed detected by the travel detection device. According to this, it is possible to reduce the shift shock according to the running speed.
In the above-described embodiment, the swash plate angle of the traveling pump is decreased when the work implement 1 is accelerated from the first speed to the second speed. The swashplate angle may be decreased if the vehicle is decelerated to

The controller 60 operates the travel pumps (first travel pump 53L, first 2 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 switching of the traveling motor.

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

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

Further, the control device 60 outputs a signal for demagnetizing the solenoid of the travel switching valve 34 at least during the decrease 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 travel switching valve 34 to the first state.

FIG. 5B is a diagram showing the control flow of the control device 60 when changing the rotational speed of the travel motor from the second speed to the first speed in the second embodiment. Note that the work machine is not in a stopped state but in a running state.
The control device 60 determines whether or not the switch 61 has been switched from the second speed to the first speed (S31). If the selector switch 61 is not switched to the second speed, that is, if the second speed is maintained (S31, No), the control device 60 changes the actual angle W11 to the target angle based on the operation of the operating device 154. W12 is set (S32). When the change-over switch 61 is switched from the second speed to the first speed (S31, Yes), the control device 60 reduces 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). 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 work machine 1 includes a prime mover 32 , travel pumps (first travel pump 53L, second travel pump 53R), travel motors (first travel motor 36L, second travel motor 36R), travel switching valve 34, control and a controller 60, which reduces the swashplate angle of the travel pump when switching from the second state to the first state. According to this, it is possible to reduce the shift shock when decelerating the speed of the work implement 1 (when switching from the second state to the first state).

When the control device 60 receives a command to switch to the first state from the change-over switch 61, the control device 60 reduces the swash plate angle of the traveling pump below the target angle, which is the swash plate angle set by the operation device 154. The traveling switching valve 34 is switched to the first state. According to this, since the actual angle is made lower than the target angle set by the operating device 154 before deceleration of the work implement 1, the flow rate of hydraulic oil discharged from the travel pump is temporarily reduced during deceleration. Therefore, it is possible to reduce the shift shock.

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 decreased in order to reduce the shift shock, the actual angle can be returned to the state before deceleration as soon as possible.
The control device 60 makes the return time T32 for restoring the swash plate angle shorter than the decrease time T31 for decreasing the swash plate angle of the traveling pump. According to this, after reducing the shift shock, the shift shock during deceleration can be reduced as much as possible in a situation where the actual angle is returned as soon as possible before deceleration.

When the changeover switch 61 is used to increase the speed from the first speed to the second speed or to decelerate from the second speed to the first speed, the control device 60 switches the travel changeover valve 34 according to the command from the changeover switch 61. The switching time is made different between acceleration and deceleration.
Specifically, as shown in FIG. 2A, the switching time "Z10" from when the changeover switch 61 issues a speed increase command to when the traveling changeover valve 34 is switched from the first state to the second state is shown in FIG. 2B. , when the switching time from issuing a deceleration command by the change-over switch 61 to switching the travel switching valve 34 from the second state to the first state is "Z11", the switching time Z10 at the time of the speed-up command is the deceleration time. It is shorter than the switching time Z11 at the time of command (Z10<Z11).

Also, as shown in FIG. 4A, the switching time from when the changeover switch 61 issues a speed increase command to when the traveling changeover valve 34 is switched from the first state to the second state is "Z12", and as shown in FIG. If the switching time from the issuance of a command by the switch 61 to the switching of the traveling switching valve 34 from the second state to the first state is "Z13", the switching time Z12 is shorter than the switching time Z13 (Z12<Z13). .

That is, the control device 60 determines that the switching times Z11 and Z13 from the operation of the changeover switch 61 to the switching of the travel switching valve 34 during deceleration are set to are set longer than the switching times Z10 and Z12 of .
Further, in the above-described embodiment, as shown in FIGS. 2A and 2B, the prime mover rotation speed is reduced during acceleration and deceleration, and as shown in FIGS. 4A and 4B, the swash plate angle is is reduced, a combination of prime mover speed and swashplate angle may be applied. For example, the control device 60 reduces the engine speed during deceleration as shown in FIG. 2B, and reduces the swash plate angle during acceleration as shown in FIG. 4A.

In the above-described embodiment, the control device 60 makes the reduction amounts ΔD1 and D2 of the motor rotation speed variable according to the running speed when issuing a shift command. Here, when the slopes K1 and K2 of the decrease in the engine speed are constant, if the amount of decrease ΔD1 and D2 is large, the time from when the decrease in the engine speed starts until it reaches the predetermined rotation speeds W3 and W4 is When the time (decrease time T1, T11) is long and the amount of decrease ΔD1, D2 is small, the decrease time T1, T11 becomes long. The control device 60 sets the switching times Z10, Z11, Z12, Z13 according to the length of the decrease times T1, T11. When Z10, Z11, Z12 and Z13 are long and the drop amounts ΔD1 and D2 are small and the drop 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 running speed when issuing a shift command.

The control device 60 makes the switching times Z10, Z11, Z12, and Z13, which are from the acquisition of the shift command until the switching of the travel switching valve 34, different between acceleration and deceleration. According to this, in a situation where gear shift shock is to be reduced by lowering the number of engine revolutions, it is easy to match the feeling of the worker (operator) at the time of speed increase with the switching of travel switching valve 34, and at the time of deceleration, Also, it is easy to match the operator's feeling with the switching of the traveling switching valve 34, and the operational feeling can be improved.

The control device 60 sets the switching times Z10, Z11, Z12, Z13 according to the running speed detected by the running detection device 67. FIG. According to this, it is possible to change the timing of the shift at the time of shifting according to the running speed, so that it is possible to further reduce the shift shock.
The control device 60 makes the switching times Z11 and Z13 during deceleration longer than the switching times Z10 and Z12 during acceleration. According to this, the shift shock during deceleration and the shift shock during acceleration can be substantially the same.

Now, in the above-described embodiment, the swash plate angle is changed by the regulator 155, but the swash plate angle may be changed by other methods. For example, as shown in FIG. 7, the discharge oil passage 40 branches in the middle, and the proportional valve 69 is connected to the section 40a of the branched discharge oil passage 40 that reaches the operating device 54. . The proportional valve 69 is an electromagnetic proportional valve whose degree of opening can be changed under the control of the control device 60 .

When the operation lever 59 of the operation device 54 is fully stroked, that is, when the operation valves 55 (55A, 55B, 55C, 55D) are substantially fully open, the control device 60 switches from the 1st speed state to the 2nd speed state by the switch 61. When a command to The swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) is lowered from the current level. After the swash plate angle of the traveling pumps (the first traveling pump 53L, the 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 of 69 is restored.

Further, when the control device 60 acquires a command from the changeover switch 61 to switch from the second speed state to the first speed state in a situation where the operation lever 59 of the operation device 54 is in a full stroke, the control device 60 changes the opening of the proportional valve 69 to the changeover switch. 61 is made smaller than the opening degree at the time of operation, the primary pressure of the hydraulic oil directed to the operation valve 55 is lowered, and as in FIG. Lower the swashplate angle than it is now. 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 of 69 is restored. Whether or not the operating lever 59 is in full stroke can be determined from the amount of operation detected by the operation detection device (sensor) 82 .

That is, as shown in FIG. 7, the proportional valve 69 provided in the discharge oil passage 40 (40a) also changes the swash plate angle of the traveling pumps (first traveling pump 53L, second traveling pump 53R) during acceleration or deceleration. can be reduced.
It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

In the above-described embodiment, the switching unit is configured by the switching switch 61 that can be manually operated by an operator or the like. When built in the control device 60 , the switching unit is composed of programs stored in the control device 60 , electricity, and electronic components (electronic electronic circuits). 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 detection information from various detection devices, such as sensors, provided in the working machine, and based on the determination result. , and outputs a control signal to the travel switching valve 34 . The traveling switching valve 34 switches to the 1st speed state when the control signal for the 1st speed state is obtained, and switches to the 2nd speed state when the control signal for the 2nd speed state is obtained.

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 at a first speed and a second state in which it is at a second speed. Alternatively, it may be a proportional valve different from the directional valve.
The travel motor may be a motor having a neutral between the first speed and the second speed.

The travel motors (first travel motor 36L, second travel motor 36R) may be axial piston motors or radial piston motors. In the case where the traveling motor is a radial piston motor, it is possible to switch to the first speed by increasing the motor displacement, and to switch to the second speed by decreasing the motor displacement.
Since the running speed changes depending on the operation of the running lever 59 , the running detection device 67 may be a device that detects the running speed based on the operation amount (operation angle) and the operation position of the control lever 59 . As described above, the second speed (second state) only needs to be faster than the first speed (first state). It can be applied even if there is

1 working machine 2 machine body 32 prime mover 34 travel switching valve 36L first travel motor 36R second travel motor 53L first travel pump 53R second travel pump 60 control device 65 accelerator 67 travel detection device

Claims (7)

a prime mover;
a traveling pump capable of changing the flow rate of hydraulic oil discharged according to the angle of the swash plate;
a travel motor rotatable by hydraulic oil discharged by the travel pump and capable of switching a rotational speed between a first speed and a second speed higher than the first speed;
a travel switching valve capable of switching between a first state in which the rotation speed of the travel motor is the first speed and a second state in which the travel motor rotation speed is 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;
an airframe provided with the prime mover, the travel pump, and the travel motor;
a running detection device capable of detecting the running speed of the aircraft;
with
The control device is a working machine that sets the amount of decrease in the angle of the swash plate according to the travel speed detected by the travel detection device . a switching unit that issues a command to switch between the first state and the second state;
an operating device capable of changing the angle of the swash plate of the traveling pump;
with
The control device sets the angle of the swash plate of the traveling pump higher than the target angle, which is the angle of the swash plate set by the operation device, when the switching unit issues a command to set the first state. 2. The work machine according to claim 1, wherein the traveling switching valve is switched to the first state after being lowered. 3. The working machine according to claim 2, wherein the control device restores the angle of the swash plate of the traveling pump after at least switching the traveling switching valve to the first state. 4. The working machine according to claim 3, wherein the control device makes a return time for restoring the angle of the swash plate shorter than a lowering time for lowering the swash plate of the traveling pump. The work machine according to any one of claims 1 to 4 , wherein the control device reduces the angle of the swash plate when the machine body is in a traveling state. a first travel device provided on the left side of the fuselage;
a second travel device provided on the right side of the fuselage;
with
The travel motors include a first travel motor that transmits travel power to the first travel device and a second travel motor that transmits travel power to the second travel device,
The travel pump is capable of operating the first travel motor and the second travel motor,
The work machine according to any one of claims 1 to 4, wherein the travel switching valve is capable of switching the first travel motor and the second travel motor between the first speed and the second speed. The working machine according to any one of claims 2 to 4 , 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.

Images