JP7399819B2 - work equipment - Google Patents

Description

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

BACKGROUND ART Conventionally, there is a technique disclosed in Patent Document 1 as a technique for decelerating and increasing speed in 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 to a plurality of switching positions according to the pressure of the hydraulic oil, and a hydraulic switching valve that can change the speed according to the switching position of the hydraulic switching valve. is equipped with a changeable travel hydraulic system.

JP2017-179922A

In the working machine of Patent Document 1, since the bleed oil passage is provided in the pressure receiving part of the hydraulic pressure switching valve, it is possible to reduce shift shock when speeding up or decelerating the working machine. However, in Patent Document 1, a bleed oil passage must be provided in order to reduce shift shock, which increases the number of parts. Furthermore, in a travel motor that does not have a neutral, it is required to sufficiently reduce shift shock.

The present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to provide a working machine that can reduce shift shock while ensuring responsiveness during deceleration. shall be.

The technical means taken by the present invention to solve the technical problems are as follows.
The working machine of the present invention includes a prime mover, a traveling pump that is driven by the power of the prime mover and can change the flow rate of hydraulic oil discharged according to the angle of the swash plate, and is rotatable by the hydraulic oil discharged by the traveling pump. a travel motor whose rotational speed is switchable between a first speed and a second speed higher than the first speed; a first state in which the rotational speed of the travel motor is set to the first speed; a travel switching valve capable of switching the rotational speed of a motor to a second state at the second speed; an operating device; and an operating valve capable of changing the angle of the swash plate of the traveling pump in accordance with the operation of the operating device. and an operating valve connected to the operating valve on the upstream or downstream side of the operating valve, and control for controlling the operating valve when switching the travel switching valve from the second state to the first state. a control device that reduces a signal from a set value to a reduced value lower than the set value and then returns to the set value , the control device reducing the signal from the set value until reaching the reduced value; In the section, a first decreasing speed of the control signal from the start point of the reducing section to the middle of the reducing section is made larger than a second decreasing speed of the control signal from the middle of the reducing section to the end point , and A time period during which the control signal decreases at the first rate of decrease is made shorter than a time period during which the control signal decreases at the second rate of decrease .

In one aspect of the present invention, the control device makes the width of decrease in which the control signal decreases at the first rate of decrease larger than the width of decrease in which the control signal decreases at the second rate of decrease, and 1 lowering speed is made larger than the return speed of the control signal from the reduced value to the set value, and the time for the control signal to decrease at the first lowering speed is set to return from the reduced value to the set value. Make it shorter than the time it takes.
Further, in one aspect of the present invention, the control device may include a first line in which the first decrease amount per unit time is constant and indicates the first decrease rate from the starting point to the halfway point, and a first line indicating the first decrease rate per unit time. a setting unit that sets a second line in which the amount of decrease is smaller and constant than the first amount of decrease and that indicates the second rate of decrease from the middle to the end point; and the second line set by the setting unit; and a control unit that controls the first lowering speed and the second lowering speed based on the first line and the second line.

Further, the working machine of the present invention includes a prime mover, a traveling pump that is driven by the power of the prime mover and is capable of changing the flow rate of the hydraulic oil discharged according to the angle of the swash plate, and a hydraulic oil discharged by the traveling pump. a travel motor that is rotatable and whose rotation speed can be switched between a first speed and 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; a travel switching valve capable of switching the rotation speed of the travel motor to a second state in which the rotational speed is set to the second speed; an operating device; and an angle of the swash plate of the travel pump capable of changing in accordance with operation of the operating device. an operating valve, an operating valve connected to the operating valve on the upstream side or downstream side of the operating valve, and controlling the operating valve when switching the travel switching valve from the second state to the first state; a control device that reduces a control signal from a set value to a reduced value lower than the set value and then returns to the set value, the control device lowers the control signal from the set value until the reduced value is reached. In the reduction section, a first rate of decrease of the control signal from the start point of the reduction section to the middle of the reduction section is greater than a second rate of decrease of the control signal from the middle of the reduction section to the end point. , a first line in which a first decrease amount per unit time is constant and shows the first decrease speed from the starting point to the middle of the reduction section, and a second decrease amount per unit time is the first decrease amount. a setting unit that sets a second line that is smaller and constant and that indicates the second decreasing speed from the middle of the reduction section to the end point; and the first line that is set by the setting unit.
and a control section that controls the first decreasing speed and the second decreasing speed of the control signal to the operating valve based on the second line, and the setting section is configured to control the travel switching valve. When switching from the second state to the first state , if the running load is larger than the reference, the first line and the second line are changed without changing the slopes of the first line and the second line. If the inflection point, which is the boundary between the two lines, is shifted to the set value side, and the running load is smaller than the reference, the inflection point, which is the boundary between the first line and the second line, is shifted to the set value side. The curve point is shifted to the reduced value side.

In one aspect of the present invention, the setting unit sets the pressure of the hydraulic oil discharged from the traveling pump as the running load, and when the running load is larger than a reference, the setting unit sets the pressure of the hydraulic oil discharged from the running pump as the running load, and when the running load is larger than a reference, The inflection value, which is the value of the control signal indicated by the inflection point, is changed so that the difference from the set value becomes smaller, and when the running load is smaller than the reference, the inflection value is changed. is changed so that the difference from the set value becomes larger.
Further, in one aspect of the present invention, the work machine includes a traveling pump pressure detection device that detects the pressure of the hydraulic fluid discharged from each of the first port and the second port of the plurality of traveling pumps, The setting unit adopts the highest pressure of the hydraulic oil pressure detected by the running pump pressure detection device as the running load , and the control unit selects the running load when the running load is equal to or higher than a predetermined threshold. In this case, the first decreasing speed and the second decreasing speed of the control signal to the operating valve are controlled based on the first line and the second line.
Further, in one aspect of the present invention, in the case where the control signal is returned to the set value after the control signal reaches the reduction value, the control device determines the amount of return per unit time at the time of the return. , the second decreasing rate is set to be larger than the second decreasing amount per unit time.

Further, the working machine of the present invention includes a prime mover, a traveling pump that is driven by the power of the prime mover and is capable of changing the flow rate of the hydraulic oil discharged according to the angle of the swash plate, and a hydraulic oil discharged by the traveling pump. a travel motor that is rotatable and whose rotation speed can be switched between a first speed and 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; a travel switching valve capable of switching the rotation speed of the travel motor to a second state in which the rotational speed is set to the second speed; an operating device; and an angle of the swash plate of the travel pump capable of changing in accordance with operation of the operating device. An operating valve, an operating valve disposed upstream or downstream of the operating valve, and a control signal for controlling the operating valve when switching the travel switching valve from the second state to the first state. a control device that increases the increase value from the set value to an increased value higher than the set value and then returns to the set value , and the control device includes: a first increase rate of the control signal from the start point of the increase section to a middle of the increase section is greater than a second increase rate of the control signal from the middle of the increase section to the end point , and the control signal The time period during which .

In one aspect of the present invention, the control device makes an increase width in which the control signal increases at the first increase rate larger than an increase width in which the control signal increases at the second increase rate, and 1 increase rate is made larger than the return rate of the control signal from the increase value to the set value, and the time during which the control signal increases at the first increase rate is set to return from the increase value to the set value. Make it shorter than the time it takes.
Further, in one aspect of the present invention, the control device may be arranged such that the first line has a constant first increase amount per unit time and indicates the first increase rate from the starting point to the halfway point, and the first line represents the first increase rate per unit time. a setting section for setting a second line in which the second increase amount is smaller and constant than the first increase amount and indicates the second increase speed from the middle to the end point; and the second line set by the setting section; and a control unit that controls the first increasing speed and the second increasing speed based on the first line and the second line.

Further, the working machine of the present invention includes a prime mover, a traveling pump that is driven by the power of the prime mover and is capable of changing the flow rate of the hydraulic oil discharged according to the angle of the swash plate, and a hydraulic oil discharged by the traveling pump. a travel motor that is rotatable and whose rotation speed can be switched between a first speed and 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; a travel switching valve capable of switching the rotation speed of the travel motor to a second state in which the rotational speed is set to the second speed; an operating device; and an angle of the swash plate of the travel pump capable of changing in accordance with operation of the operating device. An operating valve, an operating valve disposed upstream or downstream of the operating valve, and a control signal for controlling the operating valve when switching the travel switching valve from the second state to the first state. a control device that increases the increase value from the set value to an increased value higher than the set value and then returns to the set value, and the control device includes: The first increasing rate of the control signal from the start point of the increasing section to the middle of the increasing section is made larger than the second increasing rate of the control signal from the middle of the increasing section to the end point, and a first line in which a first increase amount is constant and shows the first increase rate from the start point to the middle of the increase section, and a second increase amount per unit time is smaller than the first increase amount and constant; and a second line indicating the second increasing speed from the middle of the increasing section to the end point, based on the first line and the second line set by the setting unit. , a control section that controls the first increasing speed and the second increasing speed of the control signal to the operating valve, and the setting section is configured to change the traveling switching valve from the second state to the first increasing speed. If the running load is larger than the standard when switching to the state , the gradient at the boundary between the first line and the second line is changed without changing the slopes of the first line and the second line. The inflection point is shifted to the set value side, and when the running load is smaller than the reference, the inflection point is shifted to the increased value side without changing the slopes of the first line and the second line. shift.

In one aspect of the present invention, the setting section is configured to adjust the pressure of the hydraulic fluid discharged from the travel pump.
is the running load, and when the running load is larger than the reference , as the running load increases, the inflection value, which is the value of the control signal indicated by the inflection point , is changed to the set value. If the running load is smaller than the reference value , the inflection value is changed so that the difference from the set value becomes larger .
Further, in one aspect of the present invention, the work machine includes a traveling pump pressure detection device that detects the pressure of the hydraulic fluid discharged from each of the first port and the second port of the plurality of traveling pumps, The setting unit adopts the highest pressure among the hydraulic oil pressures detected by the running pump pressure detection device as the running load, and the control unit selects the running load when the running load is equal to or higher than a predetermined threshold value. The first increase rate and the second increase rate of the control signal to the operating valve are controlled based on the first line and the second line.
Further, in one aspect of the present invention, in the case where the control signal is returned to the set value after the control signal reaches the increase value, the control device determines the amount of return per unit time at the time of the return. , larger than the second increase amount per unit time of the second increase rate.

According to the present invention, it is possible to reduce shift shock while ensuring responsiveness during deceleration.

It is a diagram showing a hydraulic system (hydraulic circuit) of a work machine. FIG. 7 is a diagram showing the relationship between a control signal and switching of the traveling motor when the speed of the traveling motor is increased. FIG. 7 is a diagram illustrating a state in which the control signal output to the operating valve is reduced by a deceleration line composed of a first line and a second line when the traveling motor is decelerated. FIG. 6 is a diagram showing a state in which the control signal output to the operating valve is reduced by an arc-shaped deceleration line having no inflection point when the traveling motor is decelerated. It is a figure which shows the modification when the operating valve is provided in a traveling oil path. It is a side view showing a track loader which is an example of a work machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, 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 be described with reference to the drawings as appropriate.
FIG. 4 shows a side view of the working machine according to the invention. FIG. 4 shows a compact track loader as an example of a work machine. However, the working machine according to the present invention is not limited to a compact track loader, but may be another type of loader working machine, such as a skid steer loader. Moreover, a work machine other than a loader work machine may be used.

As shown in FIG. 4, the work machine 1 includes a body 2, a cabin 3, a work device 4, and a traveling device 5. In the embodiment of the present invention, the front side of the driver seated in the driver's seat 8 of the work equipment 1 (left side in FIG. 4) is the front side, the rear side of the driver (the right side in FIG. 4) is the rear side, and the left side of the driver (the left side in FIG. 4) is the left side, and the driver's right side (the back side of FIG. 4) is the right side. In addition, the horizontal direction, which is a direction perpendicular to the front-rear direction, will be described as the fuselage width direction. The direction from the center of the fuselage 2 toward the right or left side will be described as the outward direction of the fuselage. In other words, the outside of the fuselage is the width direction of the fuselage, and is the direction away from the fuselage 2. The direction opposite to the outside of the fuselage will be described as inside the fuselage. In other words, the inside of the fuselage is the width direction of the fuselage, and the direction approaching the fuselage 2.

Cabin 3 is mounted on fuselage 2. This 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 outside the fuselage 2. A prime mover 32 is mounted at the rear inside the aircraft body 2.
The work device 4 includes a boom 10, a work implement 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.

The boom 10 is provided on the right and left sides of the cabin 3 so as to be vertically swingable. The work 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 part) of the boom 10 so that the boom 10 can swing vertically. The boom cylinder 14 moves the boom 10 up and down by expanding and contracting. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

The front parts of the left and right booms 10 are connected to each other by an irregularly shaped connecting pipe. The bases (rear parts) of each boom 10 are connected to each other by a circular connecting pipe.
The lift link 12, the control link 13, and the boom cylinder 14 are provided on the left and right sides of the fuselage 2, corresponding to the left and right booms 10, respectively.
The lift link 12 is provided vertically at the rear of the base of each boom 10. The upper part (one end side) of this lift link 12 is rotatably supported around a horizontal axis via a pivot shaft 16 (first pivot shaft) near the rear of the base of each boom 10. Further, the lower part (the other end side) of the lift link 12 is rotatably supported near the rear of the body 2 via a pivot shaft 17 (second pivot shaft) around a horizontal axis. The second pivot shaft 17 is provided below the first pivot shaft 16.

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

The control link 13 is provided in front of the lift link 12. One end of this 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 in 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 a horizontal axis via a pivot shaft 21 (sixth pivot shaft). The sixth pivot shaft 21 is provided in the boom 10 in front of 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 control link 13, and the tip of each boom 10 goes up and down. The control link 13 swings up and down about 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 of the boom 10 instead of the bucket 11. Examples of other working tools include attachments (preliminary attachments) such as hydraulic crushers, hydraulic breakers, angle brooms, earth augers, pallet forks, sweepers, mowers, and snow blowers.
A connecting member 50 is provided at the front of the boom 10 on the left side. The connecting member 50 is a device that connects the hydraulic equipment installed on the preliminary attachment and a first pipe material such as a pipe provided on the boom 10. Specifically, a first pipe member can be connected to one end of the connecting member 50, and a second pipe member connected to a hydraulic device as a preliminary attachment can be connected to the other end. Thereby, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The bucket cylinders 15 are arranged near the front of each boom 10, respectively. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
In this embodiment, each of the left and right traveling devices (first traveling device, second traveling device) 5 is a crawler type traveling device (including a semi-crawler type). Note that a wheel-type traveling device having front wheels 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, but is not limited to, a diesel engine.
Next, the hydraulic system of the work machine will be explained.
As shown in FIG. 1, the hydraulic system of the working machine is capable of driving the traveling device 5. The hydraulic system of the work 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 are tilted by the pilot pressure acting on the pressure receiving portions 53a and 53b, which have a forward pressure receiving portion 53a and a backward pressure receiving portion 53b on which pilot pressure acts. The angle of the board is changed. By changing the angle of the slant plate, 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 can be changed.

The first travel pump 53L and the first travel motor 36L are connected by a circulation oil path 57h, and the hydraulic oil discharged by 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 path 57i, and the hydraulic oil discharged by the second travel pump 53R is supplied to the second travel 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 aircraft body 2. The first travel motor 36L can be rotated by hydraulic oil discharged from the first travel pump 53L, and the rotation speed (number of revolutions) can be changed depending on the flow rate of the hydraulic oil. A swash plate switching cylinder 37L is connected to the first travel motor 36L, and the rotational speed (number of rotations) of the first travel motor 36L is also changed by extending 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 retracted, 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 rotation speed of the first travel motor 36L is set to a low speed (first speed). The rotation speed is set to high speed (second speed). In other words, the rotation speed of the first travel motor 36L can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

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 aircraft body 2. The second travel motor 36R can be rotated by hydraulic oil discharged from the second travel pump 53R, and the rotation speed (number of revolutions) can be changed depending on 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 (rotation number) of the second travel motor 36R is also changed by extending 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 retracted, the rotation speed of the second travel motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is extended, the rotation speed of the second travel motor 36R is set to a low speed (first speed). The rotation speed is set to high speed (second speed). In other words, the rotation speed of the second travel motor 36R can be changed between a first speed, which is a low speed, and a second speed, which is a high speed.

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 rotational speed (rotational speed) of the travel motors (first travel motor 36L, second travel motor 36R) between a first state in which the rotational speed is a first speed and a second state in which the rotation speed is a second speed. It is possible. The travel switching valve 34 includes first switching valves 71L, 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 to a first position 71L1 and a second position 71L2. The first switching valve 71L contracts the swash plate switching cylinder 37L when it is in the first position 71L1, and extends 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 travel motor 36R via an oil passage and switches to a first position 71R1 and a second position 71R2. The second switching valve 71R contracts the swash plate switching cylinder 37R when in the first position 71R1, and extends the swash plate switching cylinder 37R when in 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 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 the second switching valve 72 is in the first position 72a, and switches the first switching valve 71L and the second switching valve 71R to the first positions 71L1 and 71R1 when the second switching valve 72 is in the second position 72b. The second switching valve 71R is switched to the second position 71L2, 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 second switching valve 71R is in the first position 71R1, the travel switching valve 34 is in the first state, The rotation speed of the travel motors (first travel motor 36L, second travel motor 36R) is set to the first speed. When the second switching valve 72 is in the second position 72b, the first switching valve 71L is in the second position 71L2, and the second switching valve 71R is in the second position 71R2, the travel switching valve 34 is in the second state, and the travel motor The rotational speeds of (the first travel motor 36L and the 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, which is a low speed, and a second speed, which is a high speed.
Switching between the first speed and the second speed in the travel motor can be performed by a switching section. 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 (switch 61) is configured to increase the speed by switching from the first speed (first state) to the second speed (second state), and from the second speed (second state) to the first speed (first state). Can be switched to either deceleration or toggle.

The control device 60 is comprised of semiconductors such as a CPU and MPU, electrical and electronic circuits, and the like. The control device 60 switches the travel 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 changeover switch 61 is pressed while the travel motor is at the first speed, a command to set the travel motor to the second speed (a command to set the travel changeover valve 34 to the second state) is output to the control device 60. be done. Further, when the changeover switch 61 is pressed while the travel motor is at the second speed, a command to set the travel motor to the first speed (a command to set the travel changeover valve 34 to the first state) is output to the control device 60. . Note that the changeover switch 61 may be a push switch that can be held ON/OFF, and when it is OFF, a command to maintain the travel motor at the first speed is output to the control device 60, and the switch 61 is turned ON. In this case, a command is output to the control device 60 to maintain the travel motor at the second speed.

When the control device 60 obtains a command to place the travel switching valve 34 in the first state, it demagnetizes the solenoid of the second switching valve 72 to bring the travel switching valve 34 into the first state. Further, when the control device 60 obtains a command to set the travel switching valve 34 in the second state, it energizes the solenoid of the second switching valve 72 to bring the travel switching valve 34 into the second state.
Now, 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 a constant displacement gear pump. The first hydraulic pump P1 can discharge 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 that stores 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 a constant displacement gear pump. The second hydraulic pump P2 is capable of discharging hydraulic oil stored in the tank 22, and supplies the hydraulic oil to, for example, an oil path of a 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. do.

The operating device 54 is a device that operates the traveling pumps (first traveling pump 53L, 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 control lever 59 is supported by the control valve 55 and swings in the left-right direction (body width direction) or the front-rear direction. That is, the operating lever 59 can be operated rightward and leftward from the neutral position N, as well as forward and backward from the neutral position N. In other words, the operating lever 59 can swing in at least four directions based on the neutral position N. For convenience of explanation, the forward and backward directions, that is, the front-rear direction will be referred to as the first direction. In addition, the right and left directions, that is, the left-right direction (body width direction) may be referred to as a second direction.

Further, the plurality of operation valves 55 are operated in common, that is, by one operation lever 59. The plurality of operating valves 55 are operated based on the swinging 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 through 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 operated to output an output according to the operation amount (operation) of the previous operation when the operation lever 59 is swung forward (on one side) in the front-rear direction (first direction) (when the operation lever 59 is pre-operated). Oil pressure changes. The operation valve 55B is operated to output an output according to the amount of operation (operation) of the rear operation when the operation lever 59 is swung backward (on the other side) in the front-rear direction (first direction) (when the rear operation is performed). Oil pressure changes. In the left-right direction (second direction), when the operating lever 59 is swung to the right (one side) (when operated to the right), the operating valve 55C outputs an output according to the amount of operation (operation) of the right operation. Hydraulic oil pressure changes. When the operating lever 59 is swung to the left (the other side) in the left-right direction (second direction) (when the operating lever 59 is operated to the left), the operating valve 55D outputs an output according to the operation amount (operation) of the left operation. The pressure of the hydraulic fluid changes.

The plurality of operation valves 55 and the running pumps (first running pump 53L, second running pump 53R) are connected by running oil passage 45. In other words, the traveling pumps (the first traveling pump 53L, the second traveling pump 53R) can be operated by the hydraulic oil output from the operating valves 55 (the operating valves 55A, 55B, 55C, and 55D). It is a device.
The oil passage 45 includes a first oil passage 45a, a second oil passage 45b, a third oil passage 45c, a fourth oil passage 45d, and a fifth 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 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 forward 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 oil passage 45e is an oil passage that connects the operation valve 55, the first oil passage 45a, the second oil passage 45b, the third oil passage 45c, and the fourth 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 part 53a of the first running pump 53L via the first running oil passage 45a, and acts on the pressure receiving part 53a of the second running pump 53R via the third running 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 normally (forward rotation), and the work implement 1 moves straight forward. .

Further, when the operating lever 59 is swung rearward (in the direction of arrow A2 in FIG. 1), the operating valve 55B is operated and pilot pressure is output from the operating valve 55B. This pilot pressure acts on the pressure receiving part 53b of the first running pump 53L via the second running oil passage 45b, and acts on the pressure receiving part 53b of the second running pump 53R via the fourth running 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 (backward rotation), and the work implement 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 pilot pressure is output from the operating valve 55C. This pilot pressure acts on the pressure receiving part 53a of the first running pump 53L via the first running oil passage 45a, and acts on the pressure receiving part 53b of the second running pump 53R via the fourth running 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 in the normal direction, the second travel motor 36R rotates in the reverse direction, and the work machine 1 turns to the right.

Further, when the operating lever 59 is swung to the left (in the direction of arrow A4 in FIG. 1), the operating valve 55D is operated and pilot pressure is output from the operating valve 55D. This pilot pressure acts on the pressure receiving part 53a of the second running pump 53R via the third running oil passage 45c, and also acts on the pressure receiving part 53b of the first running pump 53L via the second running 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 reverse, and the second travel motor 36R rotates in the forward direction, causing the work implement 1 to turn to the left.

Furthermore, when the operating lever 59 is swung in a diagonal direction, the rotational direction and rotational speed of the first travel motor 36L and the second travel motor 36R are changed due to the differential pressure between the pilot pressures acting on the pressure receiving portion 53a and the pressure receiving portion 53b. The working machine 1 turns to the right or to the left while moving forward or backward.
That is, when the operating lever 59 is swung diagonally forward to the left, the work implement 1 moves forward and rotates to the left at a speed corresponding to the oscillating angle of the operating lever 59, and when the operating lever 59 is swung diagonally forward to the right, the work implement 1 rotates to the left at a speed corresponding to the oscillating angle of the operating lever 59. When the work machine 1 moves forward at a speed corresponding to the swing angle of the operating lever 59 and turns to the right, and when the operating lever 59 is swung diagonally backward to the left, the work machine 1 moves at a speed corresponding to the swing angle of the operating lever 59. When the working machine 1 turns to the left while moving backward and swings the control lever 59 diagonally backward to the right, the working machine 1 turns to the right while moving backward at a speed corresponding to the swing angle of the control lever 59.

Now, the control device 60 is connected to an accelerator 65 that sets the rotation speed of the prime mover. The accelerator 65 is provided near the driver's seat 8. The accelerator 65 includes a swingably supported accelerator lever, a swingably supported accelerator pedal, a rotatably supported accelerator volume, a slidably supported accelerator slider, and the like. Note that the accelerator 65 is not limited to the example described above. Further, a rotation detection device 66 that detects 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 prime mover rotation speed (actual rotation speed) of the prime mover 32 . The control device 60 sets a target engine rotation speed (target rotation speed) based on the operation amount of the accelerator 65, and controls the actual rotation speed to reach the set target rotation speed.

Now, as shown in FIG. 1, the discharge oil passage 40 is branched in the middle, and the discharge oil passage 40 after branching reaches a section 40a that reaches the operating device 54, that is, the upstream side of the operating valve 55. , and an operating valve 69 are connected thereto. The operating valve 69 is an electromagnetic proportional valve (proportional valve), and its opening degree can be changed under the control of the control device 60. As the control signal output from the control device 60 increases, the opening degree of the operating valve 69 increases, and as the control signal decreases, the opening degree decreases. Hereinafter, for convenience of explanation, the operating valve 69 will be referred to as the proportional valve 69.

The proportional valve 69 increases the rotation speed of the travel motor from the first speed to the second speed when switching the travel switching valve 34 from the first state (first speed) to the second state (second speed). In this case, the pressure of the hydraulic oil supplied to the operating device 54 (the pressure of the hydraulic oil on the primary side of the operating valve 55) is changed. Further, the proportional valve 69 changes the rotational speed of the travel motor from the second speed to the first speed when switching the travel switching valve 34 from the second state (second speed) to the first state (first speed). When decelerating, the pressure of the hydraulic oil supplied to the operating device 54 (the pressure of the hydraulic oil on the primary side of the operating valve 55) is changed.

The control device 60 controls the control signals such as current and voltage output to the proportional valve 69 to a reduction value (second set value) lower than the set value (first set value) during both speed increase and deceleration. This is done by lowering it to a lower level and then returning it.
FIG. 2A is a diagram showing the relationship between the setting value and reduction value of the control signal and switching of the traveling motor when increasing the speed of the traveling motor from the first speed to the second speed. On the vertical axis showing the control signal in FIG. 2A, the value is low on the origin side, and the value increases as the distance from the origin increases.

As shown in FIG. 2A, the control device 60 changes from the first state (first speed) to the second state (second speed) when the changeover switch (changeover valve) 61 is operated at time Q21. Assume that a command to change the speed (second speed command) is obtained. Upon acquiring the second speed command, the control device 60 reduces the output value W11 of the control signal output to the proportional valve 69 to a predetermined value (reduction value) W13 that is lower than the set value W12. The predetermined value (reduction value) W13 is a value that reduces the shift shock when switching from the first speed to the second speed, and is the value obtained by subtracting the reduction amount ΔD2 from the set value W12. For example, the set value W12 of the control signal for the proportional valve 69 is set based on the vehicle speed of the working machine and the actual rotational speed of the prime mover. More specifically, when the control device 60 does not obtain a second speed command (when switching is not performed), the control device 60 sets a control signal (current value) that causes the proportional valve 69 to be fully opened. . On the other hand, when the control device 60 acquires the second speed command, it changes the set value W12 of the control signal according to the vehicle speed of the working machine or the actual rotation speed of the prime mover rotation speed.

When the output value W11 reaches a predetermined value (reduction value) W13 at time Q22, the control device 60 increases the control signal to the proportional valve 69 to return the output value W11 to the set value W12. Alternatively, the control device 60 increases the control signal to the proportional valve 69 during the reduction time T21 in which the output value W11 is reduced to the predetermined value (reduction value) W13, thereby reducing the output value W11 to the set value W12 midway. Bring it back. Here, the control device 60 makes the return time T22 for returning the output value W11 from the predetermined value (reduction value) W13 to the set value W12 longer than the reduction time T21. That is, the control device 60 makes the speed at which the output value W11 is lowered to the predetermined value (reduction value) W13 faster than the return speed at which the output value W11 is returned from the predetermined value (reduction value) W13 to the set value W12.

Further, the control device 60 sends a signal that excites the solenoid of the travel switching valve 34 at least during the reduction time T21, that is, before starting the control to return the output value W11 from the predetermined value (reduction value) W13 to the set value W12. is output, and the travel 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 output value W11 to the set value W12 after switching the travel switching valve 34 to the second state.

FIG. 2B is a diagram showing the relationship between the set value of the control signal, the reduction value, and the switching of the traveling motor when decelerating the traveling motor from the second speed to the first speed. On the vertical axis showing the control signal in FIG. 2B, the value is low on the origin side, and the value increases as the distance from the origin increases.
As shown in FIG. 2B, the control device 60 changes from the second state (second speed) to the first state (first speed) when the changeover switch (switch SW) 61 is operated at time Q31. Assume that a command (1st speed command) to change the speed is obtained. Upon acquiring the first speed command, the control device 60 reduces the output value W11 of the control signal output to the proportional valve 69 to a predetermined value (reduction value) W14 that is lower than the set value W12.

Specifically, as shown in FIG. 2B, in the reduction period T31 from the set value W12 to the predetermined value (reduction value) W14, the control device 60 adjusts the control signal to the proportional valve 69 to The first decreasing speed of the output value W11 in the section (first section) T31a from the start point (time point Q31) of the reduction section T31 to the middle of the reduction section T31 is the same as that of the section (first section) from the middle of the reduction section T31 to the end point (Q32). 2 section) The output value W11 of T31b is decreased at a rate greater than the second rate. That is, when decelerating the traveling motor, the control device 60 sharply lowers the output value W11 toward the reduction value W14, and then lowers it somewhat gradually toward the reduction value W14.

The reduction in the output value W11 by the control device 60 will be explained in more detail.
As shown in FIG. 1, the control device 60 includes a setting section 60A and a control section 60B. The setting section 60A and the control section 60B are composed of an electric/electronic circuit provided in the control device 60, a program stored in the control device 60, and the like.
When the second speed command is fixed, the setting unit 60A sets a set value W12 according to the vehicle speed of the working machine and the actual rotation speed of the prime mover.

Furthermore, when the second speed command is switched to the first speed command, the setting unit 60A sets a first line L1 indicating the first decreasing speed of the output value W11 and a second line L2 indicating the second decreasing speed of the output value W11. and call. That is, when the setting unit 60A switches from the second speed command to the first speed command, the setting unit 60A moves to a process of reducing the output value W11, and in this process, when reducing the output value W11 in the reduction section T31, the setting unit 60A Control is performed so that an inflection point P25 is formed on a line (reduction line) L10 constituted by the first line L1 and the second line L2.

Further, the setting unit 60A sets the slope of the first line L1 so that the first rate of decrease is constant, that is, the amount of decrease per unit time (first amount of decrease) is constant. Further, the setting unit 60A sets the slope of the second line L2 so that the second rate of decrease is constant, that is, the amount of decrease per unit time (second amount of decrease) is constant. That is, the setting unit 60A makes the slope of the first line L1 (first amount of decrease) larger than the slope of the second line L2 (second amount of decrease). In other words, the setting unit 60A makes the slope of the second line L2 (second amount of decrease) smaller than the slope of the first line L1 (first amount of decrease).

The control unit 60B controls the first decreasing rate and the second decreasing rate of the control signal (output value W11) based on the first line L1 and second line L2 set by the setting unit 60A. That is, upon acquiring the first speed command, the control unit 60B outputs a control signal to the proportional valve 69 so that the output value W11 decreases in accordance with the first line L1. Further, the control unit 60B outputs a control signal to the proportional valve 69 so that the output value W11 decreases in accordance with the second line L2.

Note that the setting unit 60A may change either the first reduction amount or the second reduction amount based on the running load at the time of switching from the second state to the first state.
As shown in FIG. 1, the running load can be detected, for example, by the running pump pressure V detected by the running pump pressure detection device 80 provided in the circulation oil passages 57h and 57i. Specifically, the traveling pump pressure detection device 80 includes a first pressure detection device 80a, a second pressure detection device 80b, a third pressure detection device 80c, and a fourth pressure detection device 80d. The first pressure detection device 80a is provided on the first port P11 side of the left traveling motor 36L in the circulation oil passage 57h, and detects the traveling pump pressure V on the first port P11 side as the first traveling pump pressure V1. The second pressure detection device 80b is provided on the second port P12 side of the left traveling motor 36L in the circulation oil passage 57h, and detects the traveling pump pressure V on the second port P12 side as the second traveling pump pressure V2. The third pressure detection device 80c is provided on the third port P13 side of the right travel motor 36R in the circulation oil passage 57i, and detects the travel pump pressure V on the third port P13 side as the third travel pump pressure V3. The fourth pressure detection device 80d is provided on the fourth port P14 side of the right traveling motor 36R in the circulation oil passage 57i, and detects the traveling pump pressure V on the fourth port P14 side as the fourth traveling pump pressure V4.

The setting unit 60A adopts the highest hydraulic oil pressure among the pressures of the hydraulic oil discharged from the traveling pump, ie, the traveling pump pressures V (V1 to V4), as the traveling load. As shown in FIG. 2B, when the running load is large, the setting unit 60A shifts the value (inflection value) W25 of the control signal at the inflection point P25 toward the set value W12 to increase the value of the inflection point P25. increase the height. When the running load is small, the setting unit 60A shifts the inflection value W25 of the control signal at the inflection point P25 to the reduction value W14 side, thereby lowering the height of the inflection point P25.

In other words, when the running load is large, the setting unit 60A reduces the difference (deviation) between the set value W12 and the inflection value W25 without changing the slopes of the first line L1 and the second line L2. . Further, when the running load is small, the setting unit 60A increases the difference between the set value W12 and the inflection value W25 without changing the slopes of the first line L1 and the second line L2.
For example, when the running load is larger than the reference, the setting unit 60A increases the shift amount (reduces the deviation) for shifting the inflection value W25 toward the set value W12 as the running load becomes larger than the reference. . Further, when the running load is smaller than the reference, the setting unit 60A decreases the shift amount for shifting the inflection value W25 toward the reduction value W14 (increases the deviation) as the running load becomes smaller than the reference. .

When the inflection value W25 of the inflection point P25 is changed by the setting unit 60A, the control unit 60B outputs a control signal to the proportional valve 69 in accordance with the changed inflection value W25.
In the embodiment described above, the output value W11 is reduced by the first line L1 and the second line L2, but when performing the control (shock reduction control) to reduce the output value W11, referring to the running load, When the running load is equal to or greater than a predetermined threshold value, the control unit 60B may control the first lowering speed and the second lowering speed based on the first line L1 and the second line L2. In other words, when the traveling motor is switched from the second speed to the first speed, the control device 60 refers to the traveling load and, if it determines that the traveling load is greater than the threshold value, sets the After setting and changing the first decreasing speed and the second decreasing speed by the section 60A, the proportional valve 69 is controlled.

In addition, in the embodiment described above, the setting unit 60A changes the inflection value W25 of the inflection point P25 based on the running load, but it changes it based on the load on the prime mover 32 and the rotation speed of the prime mover. Good too.
As shown in FIG. 2B, the control device 60 (control unit 60B) returns the output value W11 to the set value W12 when the output value W11 reaches the predetermined value (reduced value) W14 at time Q32. When restoring the output value W11 to the set value W12, the control device 60 (control unit 60B) makes the amount of restoration per unit time at the time of restoration larger than the second amount of reduction per unit time of the second reduction speed. . In other words, the slope of the return line L3 in the return section T32 in which the output value W11 is returned to the set value W12 is made steeper than the slope of the second line L2 indicating the second decreasing speed.

In addition, in the embodiment described above, when reducing the output value W11, the inflection point P25 was provided by the first line L1 and the second line L2, but as shown in FIG. 2C, the inflection point P25 of the reduction section T31 is By making it curved, it is not necessary to form the inflection point P25. In addition, on the vertical axis showing the control signal in FIG. 2C, the value is low on the origin side, and the value increases as the distance from the origin increases.

The work equipment 1 is rotatable by a prime mover 34, traveling pumps 53L, 53R that can change the flow rate of hydraulic oil discharged according to the angle of the swash plate, and hydraulic oil discharged by the traveling pumps 53L, 53R, and has a rotational speed. A travel motor (first travel motor 36L, second travel motor 36R) that can be switched between a first speed and a second speed higher than the first speed, and a travel motor (first travel motor 36L, second travel motor 36R) ) and a second state in which the rotation speed of the travel motors (first travel motor 36L, second travel motor 36R) is set to a second speed. and an operating device 54, an operating valve 55 that can change the angle of the swash plate of the running pumps 53L and 53R according to the operation of the operating device 54, and an operating valve 55 on the upstream or downstream side of the operating valve 55. an operating valve 69 connected thereto, and a control device 60 that lowers a control signal for controlling the operating valve 69 to a reduction value W14 lower than a set value W12 and then returns the control signal when switching from the second state to the first state; In the reduction section T31 from the set value W12 to the reduction value W14, the control device 60 sets the first decreasing speed of the control signal from the start point of the reduction section T31 to the middle of the reduction section T31 as the first decreasing speed of the control signal in the reduction section T31. The rate is set to be greater than the second rate of decrease of the control signal from the halfway point to the end point. According to this, when switching from the second state to the first state (during deceleration), it is possible to reduce shift shock while ensuring the responsiveness of the travel pumps 53L and 53R.

The control device 60 generates a first line L1 in which the first amount of decrease per unit time is constant and shows the first decrease rate from the starting point to the middle, and a second line L1 where the second amount of decrease per unit time is smaller than the first amount of decrease. The setting unit 60A sets a second line L2 that is constant and indicates a second decreasing speed from the middle to the end point, and the first line L2 is set based on the first line L1 and second line L2 set by the setting unit 60A. It has a control section 60B that controls the lowering speed and the second lowering speed. According to this, the first lowering speed and the second lowering speed can be easily controlled by the first line L1 and the second line L2, and the part where the first line L1 and the second line L2 are continuous becomes an inflection point, It is possible to smoothly reduce shift shock.

When the running load is equal to or greater than a predetermined threshold, the control unit 60B controls the first lowering speed and the second lowering speed based on the first line L1 and the second line L2. According to this, it is possible to further reduce the shift shock when the vehicle is decelerated under a high running load.
The setting unit 60A changes the value W25 of the control signal at the inflection point P25, which is the boundary between the first line L1 and the second line L2, based on the running load when switching from the second state to the first state. do. According to this, by changing the value W25 of the control signal depending on the running load, it is possible to reduce shift shock without reducing responsiveness during shift (deceleration).

The setting unit 60A adopts the highest hydraulic oil pressure among the pressures of the hydraulic oil discharged from the traveling pumps 53L and 53R as the traveling load. According to this, the running load can be easily detected.
The setting unit 60A shifts the value W25 of the control signal at the inflection point P25 toward the set value W12 when the running load is large, and reduces the value W25 of the control signal at the inflection point P25 when the running load is small. Shift to the value W14 side. According to this, during gear shifting (during deceleration), shift shock can be reduced while ensuring the responsiveness of the travel pumps 53L and 53R.

When the output value W11 is restored after the output value W11 reaches the reduced value W14, the control device 60 sets the amount of restoration per unit time at the time of restoration to the second reduction per unit time of the second reduction speed. Make it bigger than the quantity. According to this, deceleration can be quickly performed while reducing shift shock.
In the embodiment described above, the operating valve 69 was provided upstream of the operating valve 55 (discharge oil path 40), but instead, it may be provided downstream of the operating valve 55 (traveling oil path 45). . For example, the operating valve 69 may be provided in the middle of the fifth oil passage 45e, or as shown in FIG. 3, the first oil passage 45a, the second oil passage 45b, the third oil passage 45c, The oil passage 51 may be branched from each of the fourth traveling oil passages 45d, and an operating valve 69 such as a variable relief valve or an electromagnetic proportional valve may be provided in the oil passage 51.

In the embodiment described above, the operating valve 69 is a valve whose opening degree increases as the value of the control signal increases, and whose opening degree decreases as the value of the control signal decreases. The valve may be such that the degree of opening decreases as the value of the control signal increases, and the degree of opening increases as the value of the control signal decreases. In the case of such an operating valve 69 (in the case of a modified example), in FIGS. 2A to 2C, on the vertical axis showing the control signal, the value is high on the origin side, and the value decreases as the distance from the origin increases. That is, in the case of the modification, since the height of the control signal is reversed in the above-described embodiment, the modification can be explained by reversing the content regarding the height. More specifically, in the embodiment described above, "decrease" is replaced by "increase", "low" is replaced by "high", "reduction section" is replaced by "increase section", "decrease speed" is replaced by "increase speed", and "decrease amount". The modification example can be explained by replacing "increase amount" with "reduction value", "increase value" with "reduction", and "increase" with "reduction".

In summary, when switching from the second state to the first state, the control device 60 increases the control signal for controlling the operating valve 69 to an increase value W14 higher than the set value W12, and then returns the control signal. In the increasing section T31 from the set value W12 to the increasing value, the control device 60 changes the first increasing speed of the control signal from the start point of the increasing section T31 to the middle of the increasing section T31 from the middle of the increasing section to the end point. greater than the second increase rate of the control signal.

The control device 60 creates a first line L1 in which the first increase amount per unit time is constant and shows the first increase rate from the starting point to the middle, and the second line L1 where the second increase amount per unit time is smaller than the first increase amount. The setting unit 60A sets a second line L2 that is constant and shows a second increasing speed from the middle to the end point, and the first line L2 is set based on the first line L1 and second line L2 set by the setting unit 60A. It has a control section 60B that controls the increasing speed and the second increasing speed.

When the running load is equal to or greater than a predetermined threshold, the control unit 60B controls the first increasing speed and the second increasing speed based on the first line L1 and the second line L2.
The setting unit 60A changes the value of the control signal at the inflection point P25, which is the boundary between the first line L1 and the second line L2, based on the running load when switching from the second state to the first state. .
The setting unit 60A shifts the value of the control signal at the inflection point P25 to the set value W12 when the running load is large, and increases the value of the control signal at the inflection point P25 to an increased value W14 when the running load is small. Shift to the side.

When restoring the control signal after the control signal reaches the increased value, the control device 60 sets the amount of restoration per unit time at the time of restoration to be less than the second amount of increase per unit time of the second increasing speed. Enlarge.
The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

In the embodiment described above, the switching section is configured with 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 into the control device 60, the switching section is composed of a program, electricity, and electronic components (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 detection information from various detection devices provided in the work machine 1, such as sensors, and based on the determination result. Then, a control signal is output to the travel switching valve 34. The travel switching valve 34 switches to the 1st speed state when a 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 may be a valve that can switch the travel motors (first travel motor 36L, second travel motor 36R) between a first state in which the travel motors are at the first speed and a second state in which the travel motors are in the second speed. It may also be a proportional valve that is different from the directional control valve.
The travel motor may be a motor having a neutral state between the first speed and the second speed.

The travel motors (first travel motor 36L, second travel motor 36R) may be an axial piston motor or a radial piston motor. When the travel motor is a radial piston motor, the motor capacity becomes large, allowing switching to the first speed, and the motor capacity becomes small, allowing switching to the second speed.
As described above, since the second speed (second state) only needs to be faster than the first speed (first state), the work equipment 1 is not limited to two gears, but has multiple gears (multiple gears). It is possible to apply even if

1: Work equipment 34: Travel switching valve 36L: Left travel motor (first travel motor)
36R: Right travel motor (second travel motor)
53L: First traveling pump (traveling pump)
53R: Second traveling pump (traveling pump)
60: Control device 60A: Setting section 60B: Control section 69: Proportional valve (operating valve)
L1: First line L10: Reduction line L2: Second line L3: Return line

Claims (14)

prime mover and
a traveling pump that is driven by the power of the prime mover and can change the flow rate of the hydraulic oil discharged according to the angle of the swash plate;
a travel motor that is rotatable by hydraulic oil discharged by the travel pump and whose rotational speed is switchable 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 rotational speed of the travel motor is set to the first speed and a second state in which the rotational speed of the travel motor is set in the second speed;
an operating device;
an operating valve capable of changing the angle of the swash plate of the traveling pump according to the operation of the operating device;
an operating valve connected to the operating valve on the upstream side or downstream side of the operating valve;
When switching the travel switching valve from the second state to the first state, the control signal for controlling the operating valve is reduced from a set value to a reduced value lower than the set value , and then returned to the set value. a control device for returning;
Equipped with
The control device is configured to control a first decreasing speed of the control signal from the start point of the reduction section to the middle of the reduction section in the reduction section from the set value to the reduction value, from the middle of the reduction section. A work machine in which the control signal is lowered at a higher rate than a second rate of decrease up to an end point , and the time period during which the control signal decreases at the first rate of decrease is shorter than the time period during which the control signal decreases at the second rate of decrease . The control device is configured to make a reduction width of the control signal at the first reduction rate larger than a reduction width of the control signal at the second reduction rate, and to adjust the first reduction rate of the control signal to the reduction width. A return speed of the control signal from the reduced value to the set value is greater than the return speed of the control signal, and the time for the control signal to decrease at the first reduction rate is shorter than the time for the control signal to return from the reduced value to the set value. The work machine described in Item 1. The control device includes:
a first line in which a first decrease amount per unit time is constant and shows the first decrease rate from the starting point to the middle; and a second decrease amount per unit time is smaller than the first decrease amount and constant. and a second line indicating the second decreasing speed from the middle to the end point;
a control unit that controls the first lowering speed and the second lowering speed based on the first line and the second line set by the setting unit;
The working machine according to claim 1 or 2 , comprising: prime mover and
a traveling pump that is driven by the power of the prime mover and can change the flow rate of the hydraulic oil discharged according to the angle of the swash plate;
a travel motor that is rotatable by hydraulic oil discharged by the travel pump and whose rotational speed is switchable 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 rotational speed of the travel motor is set to the first speed and a second state in which the rotational speed of the travel motor is set in the second speed;
an operating device;
an operating valve capable of changing the angle of the swash plate of the traveling pump according to the operation of the operating device;
an operating valve connected to the operating valve on the upstream side or downstream side of the operating valve;
When switching the travel switching valve from the second state to the first state, the control signal for controlling the operating valve is reduced from a set value to a reduced value lower than the set value, and then returned to the set value. a control device for returning;
Equipped with
The control device includes:
In the reduction section from the set value to the reduction value, the first decreasing speed of the control signal from the start point of the reduction section to the middle of the reduction section is controlled by the control signal from the middle of the reduction section to the end point. greater than the second rate of decline of the signal;
a first line in which a first decrease amount per unit time is constant and shows the first decrease speed from the starting point to the middle of the reduction section; and a second decrease amount per unit time is lower than the first decrease amount. a setting unit that sets a second line that is small and constant and that indicates the second decreasing speed from the middle of the reduction section to the end point;
a control unit that controls the first lowering speed and the second lowering speed of the control signal to the operating valve based on the first line and the second line set by the setting unit;
has
The setting unit is configured to change the slopes of the first line and the second line if the running load is larger than a reference when the running switching valve is switched from the second state to the first state. without shifting the inflection point that is the boundary between the first line and the second line to the set value side, and when the running load is smaller than the reference, the first line and the second line A work machine that shifts the inflection point to the reduction value side without changing the slope of the work machine. The setting unit sets the pressure of the hydraulic oil discharged from the traveling pump as the running load, and when the running load is larger than a reference, the setting unit sets the inflection point as the running load increases. The inflection value , which is the value of the control signal indicated, is changed so that the difference from the set value becomes smaller , and when the running load is smaller than the reference, the inflection value is changed to the difference from the set value. 5. The working machine according to claim 4, wherein the working machine is changed so that . comprising a traveling pump pressure detection device that detects the pressure of the hydraulic fluid discharged from each of the first port and the second port of the plurality of traveling pumps,
The setting section adopts the highest pressure among the pressures of the hydraulic oil detected by the traveling pump pressure detection device as a running load ,
When the running load is equal to or higher than a predetermined threshold value, the control unit is configured to control the first reduction rate and the control signal of the control signal to the operating valve based on the first line and the second line. The working machine according to any one of claims 3 to 5, wherein the second lowering speed is controlled . In the case where the control signal is returned to the set value after the control signal reaches the reduction value, the control device sets the return amount per unit time at the time of return to the unit time of the second reduction speed. The working machine according to any one of claims 1 to 6, wherein the amount of reduction is greater than the second amount of reduction per hit. prime mover and
a traveling pump that is driven by the power of the prime mover and can change the flow rate of the hydraulic oil discharged according to the angle of the swash plate;
a travel motor that is rotatable by hydraulic oil discharged by the travel pump and whose rotational speed is switchable 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 rotational speed of the travel motor is set to the first speed and a second state in which the rotational speed of the travel motor is set in the second speed;
an operating device;
an operating valve capable of changing the angle of the swash plate of the traveling pump according to the operation of the operating device;
an operating valve disposed upstream or downstream of the operating valve;
When switching the travel switching valve from the second state to the first state, the control signal for controlling the operating valve is increased from the set value to an increased value higher than the set value , and then the set value is increased. a control device for returning the
Equipped with
The control device is configured to control a first increasing speed of the control signal from the start point of the increasing section to the middle of the increasing section in the increasing section from the set value to the increasing value, from the middle of the increasing section. A working machine in which the control signal is increased at a higher rate than a second rate of increase up to an end point, and the time period during which the control signal increases at the first rate of increase is shorter than the time period during which the control signal increases at the second rate of increase . The control device makes the increase width of the control signal at the first increase rate larger than the increase width of the increase at the second increase rate, and sets the first increase rate of the control signal to the increase width. The rate of return of the control signal from the increased value to the set value is greater than the return speed of the control signal, and the time for the control signal to increase at the first increase rate is shorter than the time for the control signal to return from the increased value to the set value. The working machine according to item 8. The control device includes:
a first line in which a first increase per unit time is constant and shows the first increase rate from the starting point to the middle; and a second line in which a second increase per unit time is smaller and constant than the first increase. and a second line indicating the second increasing speed from the middle to the end point;
a control unit that controls the first increasing speed and the second increasing speed based on the first line and the second line set by the setting unit;
The working machine according to claim 8 or 9 , comprising: prime mover and
a traveling pump that is driven by the power of the prime mover and can change the flow rate of the hydraulic oil discharged according to the angle of the swash plate;
a travel motor that is rotatable by hydraulic oil discharged by the travel pump and whose rotational speed is switchable 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 rotational speed of the travel motor is set to the first speed and a second state in which the rotational speed of the travel motor is set in the second speed;
an operating device;
an operating valve capable of changing the angle of the swash plate of the traveling pump according to the operation of the operating device;
an operating valve disposed upstream or downstream of the operating valve;
When switching the travel switching valve from the second state to the first state, the control signal for controlling the operating valve is increased from a set value to an increased value higher than the set value, and then the control signal is increased to the set value. a control device for returning;
Equipped with
The control device includes:
In the increasing section from the set value to the increasing value, the first increasing speed of the control signal from the start point of the increasing section to the middle of the increasing section is controlled by the control signal from the middle of the increasing section to the end point. greater than the second increasing rate of the signal;
a first line in which a first increase per unit time is constant and shows the first increase speed from the starting point to the middle of the increase section, and a second increase per unit time is greater than the first increase a setting unit that sets a second line that is small and constant and that indicates the second increasing speed from the middle of the increasing section to the end point;
a control unit that controls the first increase rate and the second increase rate of the control signal to the operating valve based on the first line and the second line set by the setting unit;
has
The setting unit is configured to change the slopes of the first line and the second line if the running load is larger than a reference when the running switching valve is switched from the second state to the first state. without shifting the inflection point that is the boundary between the first line and the second line to the set value side, and when the running load is smaller than the reference, the first line and the second line A work machine that shifts the inflection point to the increasing value side without changing the slope of the work machine. The setting unit sets the pressure of the hydraulic oil discharged from the traveling pump as the running load, and when the running load is larger than a reference , the setting unit sets the inflection point as the running load increases . The inflection value , which is the value of the control signal indicated , is changed so that the difference from the set value becomes smaller , and when the running load is smaller than the reference , the inflection value is changed to the difference from the set value. 12. The work machine according to claim 11, wherein the working machine is changed so that the distance is increased . comprising a traveling pump pressure detection device that detects the pressure of the hydraulic fluid discharged from each of the first port and the second port of the plurality of traveling pumps,
The setting section adopts the highest pressure among the pressures of the hydraulic oil detected by the traveling pump pressure detection device as a running load ,
When the running load is equal to or higher than a predetermined threshold, the control unit controls the first increase rate and the increase rate of the control signal to the operating valve based on the first line and the second line. The working machine according to any one of claims 10 to 12, wherein the second increasing speed is controlled . When the control signal returns to the set value after the control signal reaches the increase value, the control device sets the return amount per unit time at the time of return to the unit time of the second increase speed. The work machine according to any one of claims 8 to 13, wherein the increase amount is larger than the second increase amount per hit.

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