JP2022033082A - Work machine - Google Patents

Abstract

To provide a work machine which can prevent the reduction in the work efficiency due to excessive engine drop and the occurrence of a feeling in which the travel force reduces in the recovery from the engine drop.SOLUTION: A work machine comprises: an engine; a travel pump which actuates with the power of the engine and discharges hydraulic oil; a travel motor which can rotate with the hydraulic oil discharged by the travel pump; an operation valve which can change the pilot pressure of pilot oil output to the travel pump according to the operation of an operation member; an actuation valve which can actuate with a control signal and change the primary pressure being the pilot pressure of the pilot oil supplied to the operation valve; a control device which sets the control signal output to the actuation valve; and a pressure detection device which detects the secondary pressure being the pilot pressure output by the operation valve. The control device includes a setting change part which changes the setting of the control signal output to the actuation valve on the basis of the primary pressure and the secondary pressure.SELECTED DRAWING: Figure 5

Description

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

Conventionally, the technique shown in Patent Document 1 is known as a technique for preventing an engine stall in a working machine such as a skid steer loader or a compact truck loader.
The working machine disclosed in Patent Document 1 controls an engine, an HST pump driven by the power of the engine, a traveling operation device for operating the HST pump, and a traveling primary side pressure which is the pressure on the primary side of the traveling operation device. It is equipped with a pressure control valve and a control device for controlling the pressure control valve.

The control device performs anti-stall control to prevent engine stall. In anti-stall control, the engine stall is performed by controlling the pressure control valve based on the no-load characteristic line adopted when the load is no load and the drop characteristic line adopted when a load exceeding a predetermined value is applied to the engine. Is prevented. In other words, when a traveling load exceeding a predetermined value is applied to the work equipment, the pressure control valve is controlled to sharply reduce the pressure on the primary traveling side to minimize the drop in engine speed, thereby causing engine stall. We are trying to prevent it.

Japanese Unexamined Patent Publication No. 2013-36274

However, in the technique disclosed in Patent Document 1, if the responsiveness of the anti-stall control (following of the actual pressure with respect to the target pressure of the pressure control valve) is poor, a larger engine drop than expected occurs and the work efficiency is lowered. When returning from the engine drop, the flow rate of the HST pump may decrease, resulting in a feeling that the running force decreases.
It is an object of the present invention to provide a working machine capable of preventing a decrease in work efficiency due to an excessive engine drop and a feeling that a running force is decreased when returning from the engine drop.

The technical means taken by the present invention to solve the above technical problems is characterized by the following points.
The working machine according to one aspect of the present invention includes a prime mover, a traveling pump that is operated by the power of the prime mover and discharges hydraulic oil, a traveling motor that can be rotated by the hydraulic oil discharged by the traveling pump, and an operation of operating members. An operating valve that can change the pilot pressure of the pilot oil output to the traveling pump according to the above, and an operating valve that operates by a control signal and can change the primary pressure that is the pilot pressure of the pilot oil supplied to the operating valve. A control device for setting the control signal to be output to the operating valve, and a pressure detecting device for detecting a secondary pressure which is a pilot pressure output by the operating valve, and the control device is provided with the primary pressure. It has a setting changing unit that changes the setting of the control signal output to the operating valve based on the secondary pressure and the secondary pressure.

The control device includes a calculation unit that calculates a differential pressure between a target pressure of a primary pressure determined according to the control signal and the secondary pressure.
The control device includes a storage unit that stores a correspondence relationship between the control signal and the target pressure, and the calculation unit corresponds to the output control signal when the control signal is output to the actuating valve. The target pressure to be applied is referred to from the storage unit, and the difference between the referenced target pressure and the secondary pressure is calculated as the differential pressure.

An accelerator for setting a target rotation speed of the prime mover and a rotation detection device for detecting the actual rotation speed of the prime mover are provided, and the storage unit has a first threshold value of the difference between the target rotation speed and the actual rotation speed. When the differential pressure is equal to or greater than the second threshold value, the difference between the target rotation speed and the actual rotation speed is the difference between the first line for setting the control signal corresponding to the target rotation speed based on the actual rotation speed and the target rotation speed. When the value is less than the first threshold value, a second line for setting a control signal corresponding to the target pressure based on the actual rotation speed is stored, and the setting changing unit stores the differential pressure from the second threshold value. When it becomes large, the first line is changed by changing the control signal shown in the first line.

The setting change unit ends the change of the first line when the differential pressure becomes equal to or less than the third threshold value smaller than the second threshold value.
When the setting change unit finishes the change of the first line, the setting change unit gradually returns the control signal to the value before the change of the first line.
The operating valve is an electromagnetic proportional valve that increases the opening degree in proportion to the magnitude of the current value, and in the setting changing unit, the differential pressure is larger than the second threshold value and the secondary pressure is the target pressure. If it is larger than, the first line is changed so that the primary pressure output from the actuating valve becomes smaller, and the differential pressure is larger than the second threshold value and the secondary pressure is smaller than the target pressure. The first line is changed in the direction in which the primary pressure output from the actuating valve increases.

The setting changing unit changes the setting of the control signal output to the operating valve based on the correction coefficient set corresponding to the differential pressure value.
The storage unit stores a function that defines the relationship between the differential pressure and the correction coefficient, and the setting changing unit calculates the correction coefficient by substituting the differential pressure calculated by the calculation unit into the function. do.

A first oil passage connecting the operating valve and the operating valve and a second oil passage connecting the operating valve and the traveling pump are provided, and the pressure detecting device measures the pilot pressure of the second oil passage. It is detected as the secondary pressure.

According to the present invention, it is possible to prevent a decrease in work efficiency due to an excessive engine drop and a feeling that a running force is decreased when returning from the engine drop.

It is a figure which shows the hydraulic system (hydraulic circuit) of a work machine. It is a figure which showed an example of the correspondence relation between a control signal (indicating current value) and a primary pressure. It is a figure which showed an example of the setting line which sets the control signal (the target pressure of a primary pressure) to output to a working valve based on the actual rotation speed of a prime mover. It is an operation flow which shows the operation flow which changes the setting of the control signal which a control device outputs to an operation valve. It is a figure which showed an example of the correction function which defined the relationship between the generated differential pressure and a correction coefficient. It is a figure which shows an example of the case where the operation valve is provided on the secondary side of the operation valve. It is a figure which shows the modification which changed the operation device into the operation device which operates electrically, such as a joystick. It is a side view which shows the truck loader which is an example of a working machine.

Hereinafter, suitable embodiments of the working machine according to the present invention will be described with reference to the drawings as appropriate.
FIG. 8 shows a side view of the working machine according to the present invention. FIG. 8 shows a compact truck loader as an example of a working machine. However, the working machine according to the present invention is not limited to the compact truck loader, and may be, for example, another type of loader working machine such as a skid steer loader. Further, it may be a working machine other than the loader working machine.

As shown in FIG. 8, the working machine 1 includes a machine body 2, a cabin 3, a working device 4, and a traveling device 5. In the embodiment of the present invention, the front side (left side of FIG. 8) of the driver seated in the driver's seat 8 of the work machine 1 is the front, the rear side of the driver (right side of FIG. 8) is the rear, and the left side of the driver (FIG. 8). The front side of No. 8) will be described as the left side, and the right side of the driver (the back side of FIG. 8) will be described as the right side. Further, the horizontal direction, which is a direction orthogonal to the front-rear direction, will be described as the body width direction.

The cabin 3 is mounted on the airframe 2. The cabin 3 is provided with a driver's seat 8. The working device 4 is attached to the machine body 2. A motor 32 is mounted on the rear portion of the machine body 2. The traveling device 5 is provided on the outside of the machine body 2. The traveling device 5 includes a first traveling device 5L provided on the left side of the machine body 2 and a second traveling device 5R provided on the right side of the machine body 2.

The working device 4 has a boom 10, a working tool 11, a lift link 12, a control link 13, a boom cylinder 14, and a bucket cylinder 15.
The boom 10 is provided on the right side and the left side of the cabin 3 so as to be vertically swingable. The work tool 11 is, for example, a bucket, and the bucket 11 is provided at the tip end portion (front end portion) of the boom 10 so as to be vertically swingable. The lift link 12 and the control link 13 support the base (rear portion) of the boom 10 so that the boom 10 can swing up and down. The boom cylinder 14 expands and contracts to raise and lower the boom 10. The bucket cylinder 15 swings the bucket 11 by expanding and contracting.

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

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

The control link 13 is provided in front of the lift link 12. One end of the control link 13 is rotatably supported around the horizontal axis via the pivot shaft 20 (the pivot shaft). The pivot shaft 20 is the airframe 2, and is provided at a position corresponding to the front of the lift link 12. The other end of the control link 13 is rotatably supported around the horizontal axis via the pivot shaft 21 (the pivot shaft). The pivot shaft 21 is a boom 10 and is provided in front of the pivot shaft 17 and above the pivot shaft 17.

By expanding and contracting the boom cylinder 14, each boom 10 swings up and down around the pivot shaft 16 while the base of each boom 10 is supported by the lift link 12 and the control link 13, and the tip of each boom 10 moves up and down. do. The control link 13 swings up and down around the pivot shaft 20 as each boom 10 swings up and down. The lift link 12 swings back and forth around the 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. Another working tool is, for example, an attachment (spare attachment) such as a hydraulic crusher, a hydraulic breaker, an angle bloom, an earth auger, a pallet fork, a sweeper, a mower, or a snow blower.
A connecting member 50 is provided at the front of the boom 10 on the left side. The connecting member 50 is a device for connecting the hydraulic device equipped in the spare attachment and the first pipe material such as a pipe provided in the boom 10. Specifically, the first pipe material can be connected to one end of the connecting member 50, and the second pipe material connected to the hydraulic device of the spare attachment can be connected to the other end. As a result, the hydraulic oil flowing through the first pipe material passes through the second pipe material and is supplied to the hydraulic equipment.

The bucket cylinder 15 is arranged near the front of each boom 10. By expanding and contracting the bucket cylinder 15, the bucket 11 is swung.
As each of the left and right traveling devices 5 (first traveling device 5L, second traveling device 5R), a crawler type (including a semi-crawler type) traveling device is adopted in the present embodiment. A wheel-type traveling device having front wheels and rear wheels may be adopted.

The prime mover 32 is an internal combustion engine (engine) such as a diesel engine or a gasoline engine, an electric motor, or the like. In this embodiment, the prime mover 32 is, but is not limited to, a diesel engine.
Next, the hydraulic system of the working machine 1 will be described.
The hydraulic system of the working machine 1 shown in FIG. 1 can drive the traveling device 5. The hydraulic system of the working machine 1 includes a first traveling pump 53L, a second traveling pump 53R, a first traveling motor 36L, and a second traveling motor 36R.

The first traveling pump 53L and the second traveling pump 53R are pumps driven by the power of the prime mover 32. Specifically, the first traveling pump 53L and the second traveling pump 53R are swash plate type variable displacement axial pumps driven by the power of the prime mover 32. The first traveling pump 53L and the second traveling pump 53R have a forward pressure receiving portion 53a on which a pilot pressure acts and a reverse pressure receiving portion 53b, and the swash plate is subjected to the pilot pressure acting on the pressure receiving portions 53a and 53b. The angle is changed. By changing the angle of the slab, the output (discharge amount of hydraulic oil) and the discharge direction of the hydraulic oil of the first traveling pump 53L and the second traveling pump 53R can be changed.

The first traveling pump 53L and the first traveling motor 36L are connected by a circulating oil passage 57h, and the hydraulic oil discharged by the first traveling pump 53L is supplied to the first traveling motor 36L. The second traveling pump 53R and the second traveling motor 36R are connected by a circulating oil passage 57i, and the hydraulic oil discharged by the second traveling pump 53R is supplied to the second traveling motor 36R.
The first traveling motor 36L is a motor that transmits power to the drive shaft of the traveling device 5 provided on the left side of the machine body 2. The first traveling motor 36L can be rotated by the hydraulic oil discharged from the first traveling pump 53L, and the rotation speed (rotational speed) can be changed by the flow rate of the hydraulic oil. A swash plate switching cylinder 37L is connected to the first traveling motor 36L, and the rotation speed (rotation speed) of the first traveling motor 36L can be changed by expanding and contracting the swash plate switching cylinder 37L to one side or the other side. Can be done. That is, when the swash plate switching cylinder 37L is contracted, the rotation speed of the first traveling motor 36L is set to a low speed (first speed), and when the swash plate switching cylinder 37L is extended, the first traveling motor 36L is set. The rotation speed of is set to high speed (second speed). That is, the rotation speed of the first traveling motor 36L can be changed between the first speed on the low speed side and the second speed on the high speed side.

The second traveling motor 36R is a motor that transmits power to the drive shaft of the traveling device 5 provided on the right side of the machine body 2. The second traveling motor 36R can be rotated by the hydraulic oil discharged from the second traveling pump 53R, and the rotation speed (rotational speed) can be changed by the flow rate of the hydraulic oil. A swash plate switching cylinder 37R is connected to the second traveling motor 36R, and the rotation speed (rotation speed) of the second traveling motor 36R can be changed by expanding and contracting the swash plate switching cylinder 37R to one side or the other side. Can be done. That is, when the swash plate switching cylinder 37R is contracted, the rotation speed of the second traveling motor 36R is set to a low speed (first speed), and when the swash plate switching cylinder 37R is extended, the second traveling motor 36R is set. The rotation speed of is set to high speed (second speed). That is, the rotation speed of the second traveling motor 36R can be changed between the first speed on the low speed side and the second speed on the high speed side.

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

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

That is, when the second switching valve 72 is in the first position 72a, the first switching valve 71L is in the first position 71L1, and the first switching valve 71R is in the first position 71R1, the traveling switching valve 34 is in the first state. The rotation speed of the traveling motors (first traveling motor 36L, second traveling motor 36R) is set to the first speed. When the second switching valve 72 is in the second position 72b, the first switching valve 71L is in the second position 71L2, and the first switching valve 71R is in the second position 71R2, the traveling switching valve 34 is in the second state and the traveling motor. The rotation speed of (first traveling motor 36L, second traveling motor 36R) is set to the second speed.

Therefore, the traveling switching valve 34 can switch the traveling motor (first traveling motor 36L, second traveling motor 36R) between the first speed on the low speed side and the second speed on the high speed side.
The hydraulic system of the working machine includes a first hydraulic pump P1, a second hydraulic pump P2, and an operating device 54. The first hydraulic pump P1 is a pump driven by the power of the prime mover 32, and is composed of a constant capacity type gear pump. The first hydraulic pump P1 can discharge the hydraulic oil stored in the tank 22. In particular, the first hydraulic pump P1 discharges hydraulic oil mainly used for control. For convenience of explanation, the tank 22 for storing the hydraulic oil may be referred to as a hydraulic oil tank. Further, among the hydraulic oil discharged from the first hydraulic pump P1, the hydraulic oil used for control may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

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

The operating device 54 is a device for operating the traveling pump (first traveling pump 53L, second traveling pump 53R), and the angle of the swash plate of the traveling pump (swash plate angle) can be changed. The operating device 54 includes an operating member 59 and a plurality of operating valves 55.
The operating member 59 is an operating lever 59 that is supported by the operating valve 55 and swings in the left-right direction (body width direction) or in the front-rear direction. The operating lever 59 can be operated to the right and left from the neutral position N and can be operated forward and backward from the neutral position N with respect to the neutral position N. In other words, the operating lever 59 can swing in at least four directions with respect to the neutral position N. For convenience of explanation, the front and rear directions, that is, the front-back direction is referred to as the first direction. Further, the bidirectional direction between the right side and the left side, that is, the left-right direction (airframe width direction) may be referred to as the second direction.

Further, the plurality of operating valves 55 are commonly operated, that is, operated by one operating lever 59. The plurality of operating valves 55 operate based on the swing of the operating lever 59. A discharge oil passage 40 is connected to the plurality of operation valves 55, and hydraulic oil (pilot oil) from the first hydraulic pump P1 can be supplied via the discharge oil passage 40. The discharge oil passage 40 is an oil passage connecting the operation valve 55 and the operation valve 67. Hereinafter, the discharge oil passage 40 may be referred to as a first 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 according to the operation amount (operation) of the previous operation when the operation lever 59 is swung forward (one side) in the front-rear direction (first direction) (when the operation lever 59 is operated forward). The pressure of the oil changes. The operation valve 55B is operated to output according to the operation amount (operation) of the rear operation when the operation lever 59 is swung backward (the other) in the front-rear direction (first direction) (when the operation lever 59 is rear-operated). The pressure of the oil changes. In the left-right direction (second direction), the operation valve 55C outputs when the operation lever 59 swings to the right (one side) (when the operation lever 59 is operated to the right) according to the operation amount (operation) of the right operation. The pressure of the hydraulic oil changes. The operation valve 55D outputs according to the operation amount (operation) of the left operation when the operation lever 59 is swung to the left (the other) in the left-right direction (second direction) (when the operation lever 59 is operated to the left). The pressure of the hydraulic fluid changes.

The operation valve 55 can change the pilot pressure of the pilot oil to be output to the traveling pumps (first traveling pump 53L, second traveling pump 53R) according to the operation of the operating lever (operating member) 59. The plurality of operating valves 55 and the traveling pumps (first traveling pump 53L, second traveling pump 53R) are connected by a traveling oil passage 45. In other words, the traveling pump (first traveling pump 53L, second traveling pump 53R) is hydraulic pressure that can be operated by the hydraulic oil output from the operating valve 55 (operating valve 55A, operating valve 55B, operating valve 55C, operating valve 55D). It is a device. The traveling oil passage 45 is an oil passage connecting the operation valve 55 and the traveling pump (first traveling pump 53L, second traveling pump 53R). Hereinafter, the traveling oil passage 45 may be referred to as a second oil passage 45.

The traveling oil passage 45 has a first traveling oil passage 45a, a second traveling oil passage 45b, a third traveling oil passage 45c, a fourth traveling oil passage 45d, and a fifth traveling oil passage 45e. The first traveling oil passage 45a is an oil passage connected to the advancing pressure receiving portion 53a of the traveling pump 53L. The second traveling oil passage 45b is an oil passage connected to the reverse pressure receiving portion 53b of the traveling pump 53L. The third traveling oil passage 45c is an oil passage connected to the advancing pressure receiving portion 53a of the traveling pump 53R. The fourth traveling oil passage 45d is an oil passage connected to the reverse pressure receiving portion 53b of the traveling pump 53R. The fifth traveling oil passage 45e is an oil passage connecting the operation valve 55, the first traveling oil passage 45a, the second traveling oil passage 45b, the third traveling oil passage 45c, and the fourth traveling oil passage 45d.

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

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

Further, when the operation lever 59 is swung to the right (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 via the first traveling oil passage 45a and acts on the pressure receiving portion 53b of the second traveling pump 53R via the fourth traveling oil passage 45d. As a result, the swash plate angles of the first traveling pump 53L and the second traveling pump 53R are changed, the first traveling motor 36L rotates forward and the second traveling motor 36R reverses, and the working machine 1 turns to the right.

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

Further, when the operating lever 59 is swung in an oblique direction, the rotation direction and rotation speed of the first traveling motor 36L and the second traveling motor 36R are increased by the differential pressure of the pilot pressure acting on the pressure receiving portion 53a and the pressure receiving portion 53b. Determined, the working machine 1 makes a right turn or a left turn while moving forward or backward.
That is, when the operation lever 59 is swung diagonally forward to the left, the work machine 1 turns left while advancing at a speed corresponding to the swing angle of the operating lever 59, and when the operating lever 59 is swung diagonally forward to the right. When the working machine 1 turns to the right while moving forward at a speed corresponding to the swing angle of the operating lever 59, and when the operating lever 59 is swung diagonally backward to the left, the working machine 1 is swung at a speed corresponding to the swing angle of the operating lever 59. 1 turns left while moving backward, and when the operating lever 59 is swung diagonally backward to the right, the working machine 1 turns right while moving backward at a speed corresponding to the swing angle of the operating lever 59.

Switching between the first speed and the second speed in the traveling motor (first traveling motor 36L, second traveling motor 36R) can be performed by the switching unit. The switching unit is, for example, a changeover switch 61 connected to the control device 60, and can be operated by an operator or the like. The switching unit (changeover switch 61) changes the speed 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). It can be switched to either deceleration or deceleration.

The control device 60 is composed of a CPU, a semiconductor such as an MPU, an electric / electronic circuit, and the like. The control device 60 switches the traveling switching valve 34 between the first state and the second state based on the switching operation of the changeover switch 61.
As shown in FIG. 1, the accelerator 65 and the rotation detection device 66 are connected to the control device 60. The accelerator 65 is a member that sets a target rotation speed of the prime mover 32. The accelerator 65 is provided in the vicinity of the driver's seat 8. The accelerator 65 includes an accelerator lever that is swingably supported, an accelerator pedal that is swingably supported, an accelerator volume that is rotatably supported, an accelerator slider that is slidably supported, and the like. The accelerator 65 is not limited to the above-mentioned example. The rotation detection device 66 is a sensor or the like that detects the actual rotation speed (actual motor rotation speed) of the prime mover 32.

The control device 60 performs control for preventing the motor 32 from stopping, that is, control for preventing engine stall (anti-stall control). For example, in the control device 60, in the anti-stall control, the difference (drop rotation speed) between the target rotation speed set by the accelerator 65 and the actual rotation speed detected by the rotation detection device 66 is a threshold value (hereinafter, "first threshold value"). When the above is the case, the engine stall is prevented by reducing the output of the traveling pumps (first traveling pump 53L, second traveling pump 53R).

Hereinafter, anti-stall control will be described in detail.
As shown in FIG. 1, the hydraulic system of the working machine 1 includes a working valve 67.
The actuating valve 67 is a valve capable of changing the pilot pressure of the pilot oil that operates the traveling pumps (first traveling pump 53L, second traveling pump 53R). The operating valve 67 is provided in the discharge oil passage 40 through which the pilot oil flows, and the pilot pressure (pressure receiving pressure) of the pilot oil that operates the traveling pumps (first traveling pump 53L, second traveling pump 53R) by changing the opening degree is provided. The operating pilot pressure acting on the portions 53a and 53b) is changed.

The actuating valve 67 is operated by a control signal (for example, voltage, current, etc.) of the control device 60. Hereinafter, a case where the control signal of the control device 60 is a current will be described, and the current value output as the control signal of the control device 60 is referred to as an “instructed current value”. The actuating valve 67 is an electromagnetic proportional valve whose opening degree can be changed based on the control signal of the control device 60. The electromagnetic proportional valve constituting the operating valve 67 can increase the opening degree in proportion to the magnitude of the indicated current value.

The control device 60 changes the pilot pressure (primary pressure) from the operating valve 67 to the operating device 54 by outputting a control signal to excite the solenoid 67a of the operating valve 67. As a result, the pilot pressure (primary pressure) for operating the traveling pumps (first traveling pump 53L, second traveling pump 53R) is changed.
As described above, the control device 60 outputs a control signal to change the pilot pressure (primary pressure) output to the operation valve 55. In other words, the primary pressure is determined according to the control signal output from the control device 60. In the case of the present embodiment, the opening degree of the operating valve 67 is determined according to the indicated current value which is a control signal output from the control device 60, and the primary pressure is determined according to the opening degree of the operating valve 67. More specifically, when the indicated current value increases, the opening degree of the operating valve 67 increases and the primary pressure increases, and when the indicated current value decreases, the opening degree of the operating valve 67 decreases and the primary pressure decreases. That is, there is a proportional relationship or a corresponding relationship (correlation) close to a proportional relationship between the indicated current value and the primary pressure (see FIG. 2). Therefore, the control device 60 can determine the target pressure of the primary pressure output to the operating valve 55 by determining the indicated current value which is a control signal output to the operating valve 67.

As shown in FIG. 1, a pressure detection device 68 for detecting a pilot pressure (secondary pressure) output by the operation valve 55 is connected to the control device 60. The pressure detection device 68 is a pressure sensor or the like, and is a pilot pressure (second oil passage) 45 of the traveling oil passage (second oil passage) 45 connecting the operation valve 55 and the traveling pump (first traveling pump 53L, second traveling pump 53R). Secondary pressure) is detected.
Specifically, the pressure detecting device 68 is a first pressure detecting device 68a capable of detecting the first pilot pressure which is the pressure of the hydraulic oil in the first running oil passage 45a, and the hydraulic oil in the second running oil passage 45b. A second pressure detecting device 68b capable of detecting the second pilot pressure which is the pressure, a third pressure detecting device 68c capable of detecting the third pilot pressure which is the pressure of the hydraulic oil in the third running oil passage 45c, and a fourth running It includes a fourth pressure detecting device 68d capable of detecting a fourth pilot pressure, which is the pressure of the hydraulic oil in the oil passage 45d. That is, the pressure detection device 68 detects the pilot pressure (first pilot pressure, second pilot pressure, third pilot pressure, fourth pilot pressure) of the traveling oil passage (second oil passage) 45 as the secondary pressure. In the above-described embodiment, four pilot pressures (first pilot pressure, second pilot pressure, third pilot pressure, fourth pilot pressure) can be detected, but in the anti-stall control, the first pilot pressure, Of the second pilot pressure, the third pilot pressure, and the fourth pilot pressure, the pilot pressure having the highest pressure is adopted as the secondary pressure. Alternatively, in the anti-stall control, the average value of the first pilot pressure, the second pilot pressure, the third pilot pressure, and the fourth pilot pressure may be adopted as the secondary pressure, or the first pilot pressure and the second pilot pressure may be adopted. , The differential pressure of each of the third pilot pressure and the fourth pilot pressure may be adopted as the secondary pressure without limitation. That is, in the anti-stall control, the differential pressure of a plurality of pilot pressures may be adopted as the secondary pressure, the pilot pressure itself may be adopted as the secondary pressure, or the absolute value of the differential pressure may be adopted. May be good.

Further, the pressure detecting device 68 may be any as long as it detects the pilot pressure of the traveling oil passage (second oil passage) 45, and the first traveling oil passage 45a, the second traveling oil passage 45b, and the third traveling oil passage 45c. , One pressure detection device 68 is installed in the fifth running oil passage 45d (the oil passage connected to the operation valve 55A, the operation valve 55B, the operation valve 55C, and the operation valve 55D on the input port side) on the upstream side of the fourth running oil passage 45d. It may be connected and the pilot pressure detected by the pressure detection device 68 may be adopted as the secondary pressure.

As shown in FIG. 1, the control device 60 includes a storage unit 60A, a calculation unit 60B, and a setting change unit 60C. The storage unit 60A is a non-volatile memory. The calculation unit 60B and the setting change unit 60C are an electric circuit / electronic circuit provided in the control device 60, a program stored in the control device 60, and the like.
The storage unit 60A stores the correspondence relationship (see FIG. 2) between the control signal (indicated current value) output by the control device 60 to the operating valve 67 and the target pressure of the primary pressure. Based on this correspondence, the target pressure of the primary pressure is determined according to the control signal (instructed current value).

The calculation unit 60B calculates a differential pressure (hereinafter referred to as “generated differential pressure”) between the target pressure of the primary pressure determined according to the control signal and the pilot pressure (secondary pressure) output by the operation valve 55. .. Specifically, when the control signal is output from the control device 60 to the actuating valve 67, the calculation unit 60B refers to the target pressure of the primary pressure corresponding to the output control signal from the storage unit 60A, and this The difference between the referenced target pressure and the secondary pressure is calculated as the generated differential pressure. The generated differential pressure is calculated by the formula of "generated differential pressure" = "target pressure of primary pressure"-"secondary pressure". The value of "secondary pressure" used in this calculation is an actually measured value of the pilot pressure detected by the pressure detection device 68.

The storage unit 60A stores a setting line 80 for setting a target pressure of the primary pressure based on the actual rotation speed of the prime mover 32. The setting line 80 is set based on the relationship between the actual rotation speed and the primary pressure when the operation valve 55 is in a fixed position (for example, a fully open position). FIG. 3 is a map (anti-stall map) showing an example of the setting line 80. The setting line 80 includes a first line 80A and a second line 80B.

As described above, the magnitude of the indicated current value, which is a control signal output by the control device 60 to the operating valve 67, and the target pressure of the primary pressure have a proportional relationship (see FIG. 2). Therefore, the setting line (first line 80A and second line 80B) shown in FIG. 3 is a setting line for setting a control signal (indicated current value) corresponding to the target pressure of the primary pressure based on the actual rotation speed of the prime mover 32. In other words. Therefore, in FIG. 3, the vertical axis can be referred to as a “primary pressure (target pressure)” or a “control signal (indicated current value)”.

In the first line 80A, the difference between the target rotation speed and the actual rotation speed of the prime mover 32 (drop rotation number) is equal to or higher than the first threshold value, and the differential pressure between the target pressure of the primary pressure and the secondary pressure (generated differential pressure). ) Is equal to or less than a threshold value (hereinafter referred to as “second threshold value”), this line sets a control signal (indicated current value) corresponding to the target pressure of the primary pressure based on the actual rotation speed.
The second line 80B is a control signal corresponding to the target pressure of the primary pressure based on the actual rotation speed when the difference (drop rotation speed) between the target rotation speed and the actual rotation speed of the prime mover 32 is less than the first threshold value. This is the line for setting (indicated current value).

The setting change unit 60C changes the setting of the control signal output to the operating valve 67 based on the primary pressure and the secondary pressure. Specifically, the setting change unit 60C enters the correction mode when the generated differential pressure becomes larger than the second threshold value. In the correction mode, the setting change unit 60C changes the first line 80A. The setting change unit 60C continues the correction mode until the generated differential pressure becomes equal to or less than the third threshold value, which is a value smaller than the second threshold value, and continues to change the first line 80A. The setting change unit 60C ends the correction mode when the generated differential pressure becomes equal to or less than the third threshold value. When the setting change unit 60C is not in the correction mode, the setting change unit 60C does not change the first line 80A. Hereinafter, the first line 80A that has not been changed or has not been changed may be referred to as "initial first line 80A". Further, the second threshold value is also referred to as a "differential pressure threshold value".

The change of the first line 80A by the setting change unit 60C is performed by changing the control signal shown in the first line 80A. For example, by increasing the indicated current value I10, which is a control signal set based on the actual rotation speed M10, the first line 80A is changed to move upward (see arrow D1 in FIG. 3). Alternatively, the first line 80A is moved downward by reducing the indicated current value I10, which is a control signal set based on the actual rotation speed M10 (see arrow D2 in FIG. 3).

More specifically, when the generated differential pressure is larger than the second threshold value (differential pressure threshold value) and the secondary pressure is larger than the target pressure, the setting change unit 60C reduces the primary pressure output from the operating valve 67. The first line 80A is changed in the direction (the direction in which the indicated current value decreases). When the generated differential pressure is larger than the second threshold value (differential pressure threshold value) and the secondary pressure is smaller than the target pressure, the setting change unit 60C has a direction in which the primary pressure output from the operating valve 67 increases (indicated current). The first line 80A is changed in the direction in which the value increases).

In FIG. 3, the first line 80A after changing in the direction of increasing the primary pressure is shown by the alternate long and short dash line 80A1, and the first line 80A after changing in the direction of decreasing the primary pressure is shown by the alternate long and short dash line 80A2. .. That is, the setting changing unit 60C changes the initial first line 80A indicated by the solid line to the first line 80A1 indicated by the alternate long and short dash line or the first line 80A2 indicated by the alternate long and short dash line.
As described above, when the generated differential pressure is larger than the second threshold value (differential pressure threshold value) and the secondary pressure is larger than the target pressure, the setting changing unit 60C reduces the primary pressure in the first line 80A. Excessive engine drop can be suppressed by changing. Further, the setting changing unit 60C changes the first line 80A in the direction of increasing the primary pressure when the generated differential pressure is larger than the second threshold value (differential pressure threshold value) and the secondary pressure is smaller than the target pressure. As a result, the feeling that the running force is lowered when returning from the engine drop is generated (due to the fact that the pressure (running pressure) of the circulating oil passages 57h and 57i is lowered as the flow rate of the running pumps 53L and 53R is lowered. It can be suppressed.

FIG. 4 is an operation flow showing an operation flow in which the control device 60 changes the setting of the control signal output to the operation valve 67.
The calculation unit 60B calculates the drop rotation speed by subtracting the actual rotation speed from the target rotation speed based on the target rotation speed set by the accelerator 65 and the actual rotation speed detected by the rotation detection device 66 (S1). Further, the calculation unit 60B is a differential pressure between the target pressure of the primary pressure determined according to the control signal output from the control device 60 to the operation valve 67 and the pilot pressure (secondary pressure) output by the operation valve 55. (Generated differential pressure) is calculated (S2). Next, the setting change unit 60C determines whether or not the drop rotation speed is equal to or higher than the first threshold value (S3). When the drop rotation speed is less than the first threshold value (S3, No), the setting changing unit 60C sets a control signal (indicated current value) based on the second line 80B (S4). When the drop rotation speed is equal to or higher than the first threshold value (S3, Yes), the setting changing unit 60C determines whether or not the generated differential pressure is equal to or lower than the second threshold value (differential pressure threshold value) (S5). When the generated differential pressure is equal to or less than the second threshold value (S5, Yes), the setting changing unit 60C sets a control signal (indicated current value) based on the initial first line 80A stored in the storage unit 60A (S6). ). When the generated differential pressure is larger than the second threshold value (S5, No), the setting changing unit 60C calculates a pressure difference value obtained by subtracting the target pressure of the primary pressure from the secondary pressure (S7). The setting change unit 60C sets the first line 80A1 displaced in the direction in which the primary pressure becomes larger (arrow D1 direction in FIG. 3) with respect to the first line (initial first line) 80A based on the pressure difference value. Alternatively, the first line 80A2 displaced in the direction in which the primary pressure becomes smaller (in the direction of arrow D2 in FIG. 3) with respect to the first line (initial first line) 80A is set. For example, the setting changing unit 60C obtains a displacement value with respect to the initial first line 80A from the pressure difference value and the correction coefficient, and shifts the initial first line 80A in the direction of the arrow D1 in FIG. 3 according to the displacement amount. The line 80A1 is set, and the first line 80A2 is set by shifting the initial first line 80A in the direction of the arrow D2 in FIG. 3 according to the displacement amount. The correction coefficient is a value for converting the pressure difference value into a control signal.

The setting change unit 60C sets a control signal (indicated current value) based on the changed first lines 80A1 and 80A2 (S9). The setting change unit 60C determines whether or not the generated differential pressure is equal to or less than the third threshold value (S10). The setting change unit 60C ends the correction mode when the generated differential pressure is equal to or less than the third threshold value (S10, Yes). After the correction mode ends, the setting changing unit 60C gradually returns the control signal to the value corresponding to the first line 80A or the second line 80B by gradually changing the correction coefficient.

In the above-described embodiment, the changed first lines 80A1 and 80A2 are created by shifting the first line (initial first line) 80A according to the displacement amount. The control signal corresponding to the first line 80A1 and 80A2 may be obtained by setting a reference value indicating the first line (initial first line) 80A and adding or subtracting the displacement amount to the reference value.

Hereinafter, a specific example of a change method when the setting change unit 60C changes the setting of the control signal output to the operation valve 67 will be described.
The setting change unit 60C can change the setting of the control signal output to the operating valve 67 based on the correction coefficient (gain) set corresponding to the value of the generated differential pressure (pressure difference value). The storage unit 60A stores a function (hereinafter, referred to as “correction function”) that defines the relationship between the generated differential pressure and the correction coefficient.

FIG. 5 shows an example of a correction function. As shown in FIG. 5, the correction coefficient and the generated differential pressure have a substantially linear relationship. The correction coefficient monotonously decreases as the generated differential pressure increases in the positive direction (the direction in which the negative value decreases and the positive value increases). The correction coefficient is 1 when the generated differential pressure is 0. The correction coefficient is a value less than 1 when the generated differential pressure is a positive value, and decreases substantially linearly as the generated differential pressure increases. The correction coefficient is a value exceeding 1 when the generated differential pressure is a negative value, and increases substantially linearly as the negative value of the generated differential pressure increases.

The setting change unit 60C calculates the correction coefficient by substituting the generated differential pressure calculated by the calculation unit 60B into the correction function. For example, when the correction function shown in FIG. 5 is used and the generated differential pressure calculated by the calculation unit 60B is +0.2 MPa (corresponding to the scale of +20 on the horizontal axis), the correction coefficient is calculated as 0.8. Will be done.
The setting change unit 60C changes the setting of the control signal output to the operating valve 67 based on the calculated correction coefficient. Specifically, by multiplying the calculated correction coefficient by the indicated current value of the control signal shown on the first line 80A, the indicated current value which is the control signal output to the operating valve 67 is changed. As a result, the first line 80A is changed.

When the correction coefficient is 1 (when the generated differential pressure is 0), the indicated current value is not changed even if the correction coefficient is multiplied, so that the first line 80A is not changed. When the correction coefficient is less than 1 (when the generated differential pressure is a positive value), the indicated current value decreases when the correction coefficient is multiplied, so that the primary pressure output from the operating valve 67 becomes smaller in the first line 80A. Be changed. That is, in FIG. 3, the first line 80A is changed in the direction indicated by the arrow D2. When the correction coefficient exceeds 1 (when the generated differential pressure is a negative value), the indicated current value increases when the correction coefficient is multiplied, so that the primary pressure output from the operating valve 67 increases in the first line 80A. Be changed. That is, in FIG. 3, the first line 80A is changed in the direction indicated by the arrow D1.

When the setting change unit 60C changes the setting of the control signal output to the operating valve 67 based on the correction coefficient calculated by the correction function shown in FIG. 5, the above-mentioned second threshold value (differential pressure threshold value) is 0. .. Therefore, when the generated differential pressure is 0, it is determined that the generated differential pressure is equal to or less than the second threshold value (0 or less). On the other hand, except when the generated differential pressure is 0, it is determined that the generated differential pressure (absolute value of the generated differential pressure) is larger than the second threshold value (greater than 0), and the first line 80A is changed.

However, the second threshold value (differential pressure threshold value) does not have to be 0, and is set to a value in a certain range including 0 (for example, a range from a negative value smaller than 0 by a predetermined value to a positive value larger than 0 by a predetermined value). You may. For example, when the correction function is set so that the generated differential pressure is in the range of −0.01 MPa to +0.01 MPa and the correction coefficient is 1.0, the second threshold value is −0.01 MPa to +0.01 MPa. In this case, when the absolute value of the generated differential pressure becomes larger than 0.01 MPa, it is determined that the generated differential pressure becomes larger than the second threshold value, and the first line 80A is changed.

The changing method when the setting changing unit 60C changes the setting of the control signal output to the actuating valve 67 is not limited to the method using the correction coefficient described above. For example, the setting change unit 60C may be configured to change the set value of the control signal (indicated current value) output to the operating valve 67 by changing the anti-stall map according to the generated differential pressure. .. Specifically, a plurality of different anti-stall maps (anti-stall maps in which the first line 80A is different) corresponding to a plurality of different generated differential pressures are stored in the storage unit 60A in advance, and the setting changing unit 60C is used as the generated differential pressure. The anti-stall map corresponding to the generated differential pressure is selected accordingly, and the set value of the control signal (indicated current value) output to the operating valve 67 based on the first line 80A shown in the anti-stall map is set. It may be configured to change.

In the above-described embodiment, the operating valve 67 is provided on the upstream side (discharge oil passage 40) of the operating valve 55, but instead of this, the operating valve 67 is installed in the middle of the fifth traveling oil passage 45e, for example. The actuating valve 67 may be provided.
Alternatively, as shown in FIG. 6, the operating valve 67 may be provided in the traveling oil passage 45 connected to the traveling pump (left traveling pump 53L, right traveling pump 53R). Specifically, the oil passage 51 is branched from each of the first traveling oil passage 45a, the second traveling oil passage 45b, the third traveling oil passage 45c, and the fourth traveling oil passage 45d, and the variable relief valve is connected to the oil passage 51. An operating valve 67 such as an electromagnetic proportional valve may be provided, and the opening degree of the operating valve 67 may be controlled by the first control signal and the second control signal.

In the above-described embodiment, the traveling operation device 54 is a hydraulic type in which the pilot pressure acting on the traveling pumps (first traveling pump 53L, second traveling pump 53R) is changed by the operation valve 55, which is shown in FIG. 7. As described above, the traveling operation device 54 may be an electrically operated device.
As shown in FIG. 7, the traveling operation device 54 is an operation valve 55 (operation valves 55A, 55B, 55C) composed of an operation member 59 that swings in the left-right direction (machine width direction) or the front-rear direction and an electromagnetic proportional valve. , 55D). The control device 60 is connected to an operation detection sensor that detects the operation amount and operation direction of the operation member 59. The control device 60 controls the operation valves 55 (operation valves 55A, 55B, 55C, 55D) based on the operation amount and the operation direction detected by the operation detection sensor.

When the operating member 59 is operated forward (in the A1 direction, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55A and the operating valve 55C, and the first traveling pump 53L and the second traveling pump 53R. Swing the swash plate in the direction of forward rotation (forward).
When the operating member 59 is operated rearward (A2 direction, see FIG. 1), the control device 60 outputs a control signal to the operating valve 55B and the operating valve 55D, and the first traveling pump 53L and the second traveling pump 53R. Swing the swash plate in the reverse (reverse) direction.

When the operation member 59 is operated to the right (A3 direction, see FIG. 1), the control device 60 outputs a control signal to the operation valve 55A and the operation valve 55D, and rotates the swash plate of the first traveling pump 53L in the normal direction. The swash plate of the second traveling pump 53R is swung in the reverse direction.
When the operation member 59 is operated to the left (A4 direction, see FIG. 1), the control device 60 outputs a control signal to the operation valve 55B and the operation valve 55C, and reverses the swash plate of the first traveling pump 53L. Swing in the direction, and swing the swash plate of the second traveling pump 53R in the direction of forward rotation.

The working machine 1 includes a prime mover 32, traveling pumps 53L and 53R that are operated by the power of the prime mover 32 and discharge hydraulic oil, and traveling motors 36L and 36R that can be rotated by the hydraulic oil discharged by the traveling pumps 53L and 53R. The operation valve 55 that can change the pilot pressure of the pilot oil output to the traveling pumps 53L and 53R according to the operation of the operation member 59, and the pilot pressure of the pilot oil that is operated by the control signal and supplied to the operation valve 55. An operating valve 67 capable of changing the primary pressure, a control device 60 for setting a control signal output to the operating valve 67, and a pressure detecting device 68 for detecting a secondary pressure which is a pilot pressure output by the operating valve 55. The control device 60 includes a setting change unit 60C that changes the setting of the control signal output to the operating valve 67 based on the primary pressure and the secondary pressure.

According to this, the control device 60 can change the setting of the control signal output to the operating valve 67 based on the primary pressure and the secondary pressure by the setting changing unit 60C. Therefore, it is possible to change the primary pressure, which is the pilot pressure of the pilot oil supplied by the operating valve 67 to the operating valve 55, based on the primary pressure and the secondary pressure. By making this change, even if the followability of the actuated valve 67 (followability of the secondary pressure to the primary pressure) is poor, the work efficiency is reduced due to excessive engine drop and the running force when returning from the engine drop. It is possible to prevent the occurrence of a feeling of deterioration.

Further, the control device 60 includes a calculation unit 60B for calculating the differential pressure between the target pressure of the primary pressure determined according to the control signal and the secondary pressure.
According to this, the control device 60 can calculate the differential pressure between the target pressure of the primary pressure and the secondary pressure determined according to the control signal by the calculation unit 60B. Therefore, the setting of the control signal output to the operating valve 67 based on the differential pressure calculated by the calculation is effective for suppressing excessive engine drop and preventing the occurrence of a feeling that the running force is lowered. It can be changed to an appropriate setting.

Further, the control device 60 includes a storage unit 60A that stores the correspondence between the control signal and the target pressure, and the calculation unit 60B corresponds to the output control signal when the control signal is output to the operation valve 67. The target pressure to be performed is referred from the storage unit 60A, and the difference between the referenced target pressure and the secondary pressure is calculated as the differential pressure.
According to this, the setting of the control signal output to the operating valve 67 can be appropriately changed based on the differential pressure between the target pressure and the secondary pressure.

Further, the storage unit 60A includes an accelerator 65 for setting the target rotation speed of the prime mover 32 and a rotation detection device 66 for detecting the actual rotation speed of the prime mover 32, and the storage unit 60A has a difference between the target rotation speed and the actual rotation speed. The difference between the target rotation speed and the actual rotation speed is the first between the first line 80A that sets the control signal corresponding to the target pressure based on the actual rotation speed when the threshold value is 1 or more and the differential pressure is equal to or less than the second threshold value. When the differential pressure becomes larger than the second threshold value, the setting change unit 60C stores the second line 80B and the second line 80B which sets the control signal corresponding to the target pressure based on the actual rotation speed when the value is less than the threshold value. , The first line 80A is changed by changing the control signal shown in the first line 80A.

According to this, the load applied to the prime mover 32 is a low load (the difference between the target rotation speed and the actual rotation speed is less than the first threshold value), and the load applied to the prime mover 32 is a high load (the target rotation speed and the actual rotation speed). When the difference from the number is greater than or equal to the first threshold value and the differential pressure is low (below the second threshold value), and when the load applied to the prime mover 32 is high and the differential pressure is high (greater than the second threshold value). The setting of the control signal output to the operating valve 67 can be appropriately changed according to the three cases of.

The setting change unit 60C is the first when the differential pressure becomes equal to or less than the third threshold value smaller than the second threshold value.
Finish the change of line 80A. According to this, the change of the first line 80A can be continued until the differential pressure becomes the third threshold value smaller than the second threshold value.
When the setting change unit 60C finishes the change of the first line 80A, the setting change unit 60C gradually returns the control signal to the value before the change of the first line 80A. According to this, the control signal output to the operating valve 67 can be gradually returned from the control signal set by the change of the first line 80A to the first line 80A before the change, and the change of the first line 80A is completed. It is possible to suppress abrupt pressure fluctuations of the secondary pressure (primary pressure) at times.

Further, the operating valve 67 is an electromagnetic proportional valve that increases the opening degree in proportion to the magnitude of the current value, and the setting changing unit 60C has a differential pressure larger than the second threshold value and a secondary pressure higher than the target pressure. If the pressure is large, the first line is changed so that the primary pressure output from the operating valve 67 becomes smaller, and if the differential pressure is larger than the second threshold value and the secondary pressure is smaller than the target pressure, the operating valve 67 is used. The first line is changed in the direction in which the primary pressure output from is increased.

According to this, when the differential pressure is larger than the second threshold value and the secondary pressure is larger than the target pressure, the first line is changed so that the primary pressure output from the operating valve 67 becomes smaller. It is possible to suppress the occurrence of excessive engine drop and suppress the decrease in work efficiency. Further, when the differential pressure is larger than the second threshold value and the secondary pressure is smaller than the target pressure, the first line is changed in the direction in which the primary pressure output from the operating valve 67 becomes larger, so that the engine drop can be removed. It is possible to prevent the occurrence of a feeling that the running force is reduced at the time of return.

Further, the setting changing unit 60C changes the setting of the control signal output to the operating valve 67 based on the correction coefficient set corresponding to the differential pressure value.
According to this, since the setting of the control signal output to the operating valve 67 can be changed by using the correction coefficient set corresponding to the differential pressure value, the operation corresponds to the differential pressure value. The setting of the control signal output to the valve 67 can be easily and appropriately changed.

Further, the storage unit 60A stores a function that defines the relationship between the differential pressure and the correction coefficient, and the setting change unit 60C calculates the correction coefficient by substituting the differential pressure calculated by the calculation unit 60B into the function.
According to this, the correction coefficient can be calculated easily and accurately by using the function that defines the relationship between the differential pressure and the correction coefficient.

Further, the working machine 1 includes a first oil passage 40 connecting the operation valve 55 and the operating valve 67, and a second oil passage 45 connecting the operation valve 55 and the traveling pumps 53L and 53R, and the pressure detecting device 68. Detects the pilot pressure of the second oil passage 45 as the secondary pressure.
According to this, the secondary pressure, which is the pilot pressure output by the operation valve 55, can be reliably and accurately detected by the pressure detection device 68.

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

1 Work machine 32 Motor 36L, 36R Travel motor 40 First oil passage 45 Second oil passage 53L, 53R Travel pump 55 Operation valve 59 Operation member 60 Control device 60A Storage unit 60B Calculation unit 60C Setting change unit 65 Accelerator 66 Rotation detection device 67 Actuating valve 68 Pressure detector 80A 1st line 80B 2nd line

Claims (10)

The prime mover and
A traveling pump that is operated by the power of the prime mover and discharges hydraulic oil,
A traveling motor that can be rotated by the hydraulic oil discharged by the traveling pump,
An operating valve that can change the pilot pressure of the pilot oil output to the traveling pump according to the operation of the operating member,
An operating valve that operates by a control signal and can change the primary pressure, which is the pilot pressure of the pilot oil supplied to the operating valve.
A control device that sets the control signal to be output to the operating valve, and
A pressure detection device that detects the secondary pressure, which is the pilot pressure output by the operation valve, and
Equipped with
The control device is a working machine having a setting changing unit for changing the setting of a control signal output to the operating valve based on the primary pressure and the secondary pressure. The working machine according to claim 1, wherein the control device includes a calculation unit that calculates a differential pressure between a target pressure of a primary pressure determined in response to the control signal and the secondary pressure. The control device includes a storage unit that stores the correspondence between the control signal and the target pressure.
When the control signal is output to the actuating valve, the arithmetic unit refers to the target pressure corresponding to the output control signal from the storage unit, and the difference between the referenced target pressure and the secondary pressure. The working machine according to claim 2, wherein the pressure is calculated as the differential pressure. The accelerator that sets the target rotation speed of the prime mover and
A rotation detection device that detects the actual rotation speed of the prime mover, and
Equipped with
The storage unit is a control signal corresponding to the target pressure based on the actual rotation speed when the difference between the target rotation speed and the actual rotation speed is equal to or more than the first threshold value and the differential pressure is equal to or less than the second threshold value. The first line for setting the target pressure and the second line for setting the control signal corresponding to the target pressure based on the actual rotation speed when the difference between the target rotation speed and the actual rotation speed is less than the first threshold value. And remember,
The third aspect of claim 3 is that the setting changing unit changes the first line by changing the control signal shown in the first line when the differential pressure becomes larger than the second threshold value. Working machine. The working machine according to claim 4, wherein the setting changing unit ends the change of the first line when the differential pressure becomes equal to or less than the third threshold value smaller than the second threshold value. The working machine according to claim 5, wherein the setting changing unit gradually returns the control signal to the value before the change of the first line when the change of the first line is completed. The actuated valve is an electromagnetic proportional valve that increases the opening degree in proportion to the magnitude of the current value.
The setting change part is
When the differential pressure is larger than the second threshold value and the secondary pressure is larger than the target pressure, the first line is changed in the direction in which the primary pressure output from the actuating valve becomes smaller, and the differential pressure is reduced. Any one of claims 4 to 6 for changing the first line in a direction in which the primary pressure output from the actuated valve increases when the secondary pressure is larger than the second threshold value and smaller than the target pressure. The working machine described in the section. The setting change unit according to any one of claims 2 to 7 which changes the setting of the control signal output to the actuating valve based on the correction coefficient set corresponding to the value of the differential pressure. Working machine. The storage unit stores a function that defines the relationship between the differential pressure and the correction coefficient.
The working machine according to claim 8, wherein the setting changing unit calculates the correction coefficient by substituting the differential pressure calculated by the calculation unit into the function. A first oil passage connecting the operating valve and the operating valve,
A second oil passage connecting the operation valve and the traveling pump,
Equipped with
The working machine according to any one of claims 1 to 9, wherein the pressure detecting device detects the pilot pressure of the second oil passage as the secondary pressure.

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