JP6707514B2 - Hydraulic system of work equipment - Google Patents

Description

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

BACKGROUND ART Conventionally, in a working machine such as a skid steer loader and a compact truck loader, a technique disclosed in Patent Document 1 is known as a technique for preventing engine stall.
In the working machine of Patent Document 1, an engine, an HST pump driven by the power of the engine, a travel operating device that operates the HST pump, and a pressure control that controls a travel primary side pressure that is a primary side pressure of the travel operating device. A valve and a control device for controlling the pressure control valve are provided.

The control device controls the pressure control valve based on the no-load characteristic line that is adopted when the load is no-load and the drop characteristic line that is used when a load greater than a predetermined value is applied to the engine to prevent engine stall. To prevent. In other words, by controlling the pressure control valve to suddenly reduce the traveling primary side pressure when a traveling load of a predetermined amount or more acts on the work machine, the drop in the engine rotational speed is minimized, thereby reducing the engine stall. We are trying to prevent it.

JP, 2013-78115, A

The operator of the work implement feels that the engine is operating sufficiently because the engine speed decreases while the traveling load is being applied to the work implement. Therefore, if a load is applied to the work implement but the engine speed does not decrease, the driver may be suspicious that the engine is not operating sufficiently.
On the other hand, when the engine rotational speed is significantly reduced due to the load acting on the work machine, unless the engine rotational speed is prevented from falling, engine stall will occur.

An object of the present invention is to provide a hydraulic system for a working machine capable of achieving both a driver's feeling when the load is applied to the prime mover and prevention of engine stall.

Technical means taken by the present invention to solve the above technical problems are characterized by the following points.
The hydraulic system of the working machine includes a prime mover, a setting member for setting a target rotation speed of the prime mover, a hydraulic pump operable by driving the prime mover and discharging hydraulic oil, and a hydraulic oil discharged from the hydraulic pump. Characteristics of the relationship between the pressure of the hydraulic oil of the working valve and the actual rotational speed of the prime mover when the load of the prime mover is equal to or higher than a predetermined value, the hydraulic valve that is supplied, the hydraulic equipment that can be operated by the hydraulic oil of the working valve, And a storage unit that stores a plurality of first control characteristics having different inclinations that are determined corresponding to the target rotation speed, and if the load on the prime mover is equal to or greater than a predetermined value, depending on the target rotation speed, And a control unit that controls the actuating valve based on the first control characteristics having different predetermined inclinations.

The control unit controls the actuating valve by using the first control characteristic in which the inclination is set smaller as the target rotation speed increases.
The hydraulic system of the working machine includes a switch capable of changing the first control characteristic.
The hydraulic system of the working machine includes a switch capable of changing the determination value.
The hydraulic system of the working machine includes a prime mover, a setting member for setting a target rotation speed of the prime mover, a hydraulic pump operable by driving the prime mover and discharging hydraulic oil, and a hydraulic oil discharged from the hydraulic pump. Characteristics of the relationship between the pressure of the hydraulic oil of the working valve and the actual rotational speed of the prime mover when the load of the prime mover is equal to or higher than a predetermined value, the hydraulic valve that is supplied, the hydraulic equipment that can be operated by the hydraulic oil of the working valve, And a plurality of first control characteristics in which the inclinations determined in correspondence with the target rotational speed are parallel or different in inclination, the pressure of the hydraulic oil of the operating valve and the actual operation of the engine when the load of the engine is less than a predetermined value. A storage unit that stores a second control characteristic indicating a relationship with the rotation speed, and the second control characteristic when the amount of decrease in the actual rotation speed from the target rotation speed is less than a predetermined determination value. Is controlled based on the control valve, and when the decrease amount is equal to or greater than the determination value of the actual rotation speed, the operation valve of the operation valve is determined based on the first control characteristic determined according to the target rotation speed. And a control unit that performs control.

The hydraulic system of the working machine includes a prime mover, a setting member for setting a target rotation speed of the prime mover, a hydraulic pump operable by driving the prime mover and discharging hydraulic oil, and a hydraulic oil discharged from the hydraulic pump. It is a characteristic showing the relationship between the supplied operating valve, the hydraulic equipment that can be operated by the operating oil of the operating valve, the pressure of the operating oil of the operating valve, and the actual rotational speed of the prime mover, and corresponds to the target rotational speed. A storage unit that stores a plurality of first control characteristics having different inclinations determined by the above, and if the amount of decrease in the actual rotation speed from the target rotation speed is equal to or greater than a predetermined determination value, the target And a control unit that controls the actuating valve based on the first control characteristics having different inclinations determined according to the rotation speed.

The hydraulic system of the working machine includes a prime mover, a setting member for setting a target rotation speed of the prime mover, a hydraulic pump operable by driving the prime mover and discharging hydraulic oil, and a hydraulic oil discharged from the hydraulic pump. It is a characteristic showing the relationship between the supplied operating valve, the hydraulic equipment that can be operated by the operating oil of the operating valve, the pressure of the operating oil of the operating valve, and the actual rotational speed of the prime mover, and corresponds to the target rotational speed. A storage unit for storing a plurality of first control characteristics which are parallel to each other or have different inclinations, and a second control characteristic which shows the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotational speed of the prime mover. When the reduction amount of the actual rotation speed from the target rotation speed is less than a predetermined determination value, the operation valve is controlled based on the second control characteristic, and the reduction amount is the actual rotation speed. And a control unit that controls the operating valve based on the first control characteristic that is determined according to the target rotation speed when the number of rotations is equal to or greater than the determination value.

According to the present invention, it is possible to achieve both the driver's feeling and the prevention of engine stall when a load acts on the prime mover.

It is a figure which shows the hydraulic system (hydraulic circuit) of the traveling system of a working machine. It is a figure which shows the hydraulic system (hydraulic circuit) of the working system of a working machine. It is a figure showing the relation between engine number of rotations and primary running pressure, and is a characteristic figure showing a 1st embodiment of anti-stall control. It is a figure which shows the relationship between an engine speed and running primary pressure, and is a characteristic view which shows 2nd Example of anti-stall control. It is a side view showing a truck loader which is an example of a working machine. It is a side view which shows some truck loaders in the state which raised the cabin.

Hereinafter, preferred embodiments of a hydraulic system for a working machine and a working machine including the hydraulic system according to the present invention will be described with reference to the drawings as appropriate.
[First Embodiment]
First, the overall configuration of the working machine will be described.
As shown in FIGS. 5 and 6, the work machine 1 according to the present invention includes a machine body frame 2, a work device 3 mounted on the machine body frame 2, and a traveling device 4 that supports the machine body frame 2. .. 5 and 6 show a truck loader as an example of the working machine, the working machine according to the present invention is not limited to the truck loader, and may be, for example, a tractor, a skid steer loader, a compact truck loader, a wheel loader. , A backhoe, or the like. In the present invention, the front side (left side in FIG. 5) of the driver seated in the driver's seat 13 of the work machine 1 is front, the rear side (right side in FIG. 5) is rear, and the left side (FIG. 5) of the driver. The front side) will be described as the left side, and the driver's right side (the back side in FIG. 5) will be described as the right side.

A cabin 5 is mounted on the upper part of the machine body frame 2 and on the front part thereof. A rear portion of the cabin 5 is supported by a support bracket 11 of the machine body frame 2 so as to be swingable around a support shaft 12. The front portion of the cabin 5 can be placed on the front portion of the machine body frame 2.
A driver's seat 13 is provided in the cabin 5. On one side (for example, the left side) of the driver's seat 13, a traveling operation device 14 for operating the traveling device 4 is arranged.

The traveling device 4 is composed of a crawler type traveling device. The traveling device 4 is provided on the lower left side of the machine body frame 2 and on the lower right side of the machine body frame 2. The traveling device 4 includes a first traveling portion 21L that is hydraulically driven and a second traveling portion 21R that is hydraulically operated. The work machine 1 can travel by the first traveling unit 21L and the second traveling unit 21R.
The work device 3 includes a boom 22L, a boom 22R, and a bucket 23 (work implement). The boom 22L is arranged on the left of the machine body frame 2. The boom 22R is arranged on the right of the machine body frame 2. The boom 22L and the boom 22R are connected to each other by a connecting body. The boom 22L and the boom 22R are supported by the first lift link 24 and the second lift link 25. A lift cylinder 26, which is a double-acting pressure cylinder, is provided between the bases of the booms 22L and 22R and the lower rear portion of the machine body frame 2. By simultaneously expanding and contracting the lift cylinder 26, the boom 22L and the boom 22R swing up and down.

The bucket 23 is attached to the tip ends of the boom 22L and the boom 22R. Mounting brackets 27 are rotatably pivoted around the horizontal axis on the tip ends of the booms 22L and 22R, respectively, and the back sides of the buckets 23 are mounted on the mounting brackets 27 provided on the left and right sides.
Further, a tilt cylinder 28, which is a double-acting hydraulic cylinder, is interposed between the mounting bracket 27 and the midway portions of the boom 22L and the boom 22R on the tip side. As the tilt cylinder 28 expands and contracts, the bucket 23 swings (squeezing operation and dumping operation).

The bucket 23 is detachable from the mounting bracket 27. By removing the bucket 23 and attaching various attachments (hydraulic drive type working tools having hydraulic actuators described later) to the mounting bracket 27, various work other than excavation (or other excavation work) can be performed. ing.
A prime mover 29 is provided on the rear side of the bottom wall of the machine body frame 2, and a fuel tank and a hydraulic oil tank 31 are provided on the front side of the bottom wall of the machine body frame 2. The prime mover 29 is, for example, a diesel engine. The prime mover 29 may be an electric motor, or may be a diesel engine and an electric motor. A diesel engine is sometimes called simply an engine.

Next, the hydraulic system of the working machine according to the present invention will be described.
FIG. 1 shows an overall view of a traveling hydraulic system. FIG. 2 shows an overall view of the working hydraulic system.
First, the hydraulic system of the traveling system will be described.
As shown in FIGS. 1 and 2, the hydraulic system (hydraulic circuit) includes a first hydraulic pump P1 and a second hydraulic pump P2. The first hydraulic pump P1 and the second hydraulic pump P2 are hydraulic pumps that can be operated by driving the prime mover 29. The first hydraulic pump P1 and the second hydraulic pump P2 are driven by the power of the prime mover 29 to discharge hydraulic oil. The first hydraulic pump P1 and the second hydraulic pump P2 are constituted by, for example, constant capacity type gear pumps.

The first hydraulic pump P1 (main pump) is used for driving the lift cylinder 26, the tilt cylinder 28, or the hydraulic actuator of the attachment attached to the tip side of the boom 22. The second hydraulic pump P2 (pilot pump, charge pump) is mainly used for supplying a control signal (pilot pressure). Hereinafter, for convenience of description, the hydraulic oil discharged from the second hydraulic pump P2 and the hydraulic oil for control signals may be referred to as pilot oil, and the pressure of the pilot oil may be referred to as pilot pressure.

As shown in FIG. 1, a discharge oil passage 100a is connected to the second hydraulic pump P2. A first supply/discharge passage 100b and a second supply/discharge passage 100c are connected to the discharge oil passage 100a. The first drive circuit 32A and the second drive circuit 32B are connected to the first supply/discharge path 100b. The travel operation device 14 is connected to the second oil supply/discharge passage 100c. The operation valve 45 is connected to a middle portion of the second oil supply/discharge passage 100c. Therefore, the working oil discharged from the second hydraulic pump P2 is supplied to the working valve 45. The actuation valve 45 is constituted by an electromagnetic proportional valve in this embodiment.

The first drive circuit 32A is a circuit that drives the first traveling unit 21L provided on the left. 32 A of 1st drive circuits and 21 L of 1st traveling parts comprise HST (hydrostatic transmission). The second drive circuit 32B is a circuit that drives the second traveling unit 21R provided on the right. The 2nd drive circuit 32B and the 2nd running part 21R comprise HST (hydrostatic transmission).

The first drive circuit 32A includes a traveling pump (HST pump) 66. The traveling pump 66 is a hydraulic device that can be operated by the pilot oil (operating oil) output from the operating valve 45. The traveling pump 66 is connected to the corresponding traveling motor (HST motor) 57 of the first traveling portion 21L by the shift oil passage 100h and the shift oil passage 100i.
Note that the second drive circuit 32B has the same structure as the first drive circuit 32A, and a description thereof will be omitted.

The traveling pump 66 is a swash plate type variable displacement axial pump driven by the power of the prime mover 29 and a pilot type hydraulic pump (swash plate type variable displacement hydraulic pump) in which the angle of the swash plate is changed by pilot pressure. .. Specifically, the traveling pump 66 includes a forward pressure receiving portion 66a on which a pilot pressure acts and a reverse pressure receiving portion 66b.
The angle of the swash plate is changed by the pilot pressure acting on the pressure receiving portions 66a and 66b. When the angle of the swash plate is changed, the discharge direction and discharge amount of the hydraulic oil are changed, whereby the rotation output of the first traveling portion 21L and the second traveling portion 21R is changed.

The first traveling portion 21L includes a traveling motor 57 (hydraulic motor for traveling), a swash plate switching cylinder 58, a first hydraulic pressure switching valve 63, a brake mechanism 59, a flushing valve 60, and a flushing relief valve 61. Have.
The traveling motor 57 is a hydraulic device that operates with pilot oil (operating oil). The traveling motor 57 is, for example, a swash plate type variable displacement axial motor capable of shifting between high and low speeds. The swash plate of the traveling motor 57 is provided with a swash plate switching cylinder 58 that can expand and contract. By expanding and contracting the swash plate switching cylinder 58, the angle of the swash plate of the traveling motor 57 can be changed. By changing the angle of the swash plate of the traveling motor 57, the traveling motor 57 shifts to the first speed or the second speed.

The first hydraulic pressure switching valve 63 is a two-position switching valve having a spool that can move between a first position 63a and a second position 63b according to the pressure of pilot oil (pilot pressure). The spool of the first hydraulic pressure switching valve 63 moves to the second position 63b when the pilot pressure reaches a predetermined pressure, and the operating state changes. The spool of the first hydraulic pressure switching valve 63 is returned to the first position 63a by the spring when the pilot pressure becomes less than the predetermined pressure, and the operating state changes. When the spool of the first hydraulic pressure switching valve 63 has moved to the first position 63a and is in the operating state, pilot oil escapes from the swash plate switching cylinder 58 and contracts, and the travel motor 57 enters the first speed state. When the spool of the first hydraulic pressure switching valve 63 has moved to the second position 63b and is in the operating state, the pilot oil is supplied to the swash plate switching cylinder 58 and extends, and the traveling motor 57 enters the second speed state.

The switching of the first hydraulic pressure switching valve 63 is performed by the second hydraulic pressure switching valve 62. The first hydraulic pressure switching valve 63 and the second hydraulic pressure switching valve 62 are connected by a third supply/discharge passage 100d. The second hydraulic pressure switching valve 62 is a two-position switching valve having a spool that can move between a first position and a second position according to the pressure of pilot oil (pilot pressure). When the second hydraulic pressure switching valve 62 is in the first position, the first hydraulic pressure switching valve 63 is in the first position 63a. When the second hydraulic pressure switching valve 62 is in the second position, the first hydraulic pressure switching valve 63 is in the second position 63b. The switching of the second hydraulic pressure switching valve 62 can be performed by an electric signal, pilot pressure, mechanical operation, or the like. Therefore, the travel motor 57 can be switched to the first speed or the second speed by switching the second hydraulic pressure switching valve 62 to the first position or the second position.

The traveling pump 66 and the traveling motor 57 are operated by the traveling operation device 14. The travel operating device 14 has a plurality of remote control valves, a travel lever 40, and first to fourth shuttle valves 41, 42, 43, 44. The plurality of remote control valves include a remote control valve 36, a remote control valve 37, a remote control valve 38, and a remote control valve 39. The remote control valves 36, 37, 38, 39 are operated in common, that is, by one traveling lever 40. The remote control valves 36, 37, 38, 39 change the pressure of the hydraulic oil according to the operation of the traveling lever 40 (operation member).

The traveling lever 40 can tilt from the neutral position in the front-rear direction, the width direction orthogonal to the front-rear direction, and the oblique direction. By tilting the travel lever 40, the remote control valves 36, 37, 38, 39 of the travel operation device 14 are operated. Then, the pilot pressure proportional to the operation amount from the neutral position of the traveling lever 40 is output from the secondary side ports of the remote control valves 36, 37, 38, 39.

When the traveling lever 40 is tilted to the front side (direction of arrow A1 in FIG. 1), the remote control valve 36 is operated and pilot pressure is output from the remote control valve 36. This pilot pressure acts on the forward pressure receiving portion 66a of the first drive circuit 32A from the first shuttle valve 41 via the first flow path 46, and at the same time from the second shuttle valve 42 to the second flow path 47 via the second flow path 47. It acts on the forward pressure receiving portion 66a of the drive circuit 32B. As a result, the output shafts 57a of the first traveling unit 21L and the second traveling unit 21R rotate forward (rotate forward) at a speed proportional to the tilt amount of the traveling lever 40, and the track loader 1 travels straight forward.

When the traveling lever 40 is tilted rearward (in the direction of arrow A2 in FIG. 1), the remote control valve 37 is operated and the pilot pressure is output from the remote control valve 37. This pilot pressure acts on the reverse drive pressure receiving portion 66b of the first drive circuit 32A from the third shuttle valve 43 via the third flow path 48, and at the same time from the fourth shuttle valve 44 to the second flow path 49 via the fourth flow path 49. It acts on the reverse pressure receiving portion 66b of the drive circuit 32B. As a result, the output shafts 57a of the first traveling portion 21L and the second traveling portion 21R are reversely rotated (reverse rotation) at a speed proportional to the amount of tilt of the traveling lever 40, and the track loader 1 travels straight backward.

Further, when the traveling lever 40 is tilted to the right (A3 direction shown in FIG. 1), the remote control valve 38 is operated and pilot pressure is output from the remote control valve 38. This pilot pressure acts on the forward pressure receiving portion 66a of the first drive circuit 32A from the first shuttle valve 41 via the first flow path 46, and the second drive from the fourth shuttle valve 44 via the fourth flow path 49. The circuit 32B acts on the reverse pressure receiving portion 66b. As a result, the output shaft 57a of the first traveling unit 21L rotates in the normal direction and the output shaft 57a of the second traveling unit 21R rotates in the reverse direction, so that the track loader 1 turns to the right.

When the traveling lever 40 is tilted to the left (direction A4 in FIG. 1), the remote control valve 39 is operated and the pilot pressure is output from the remote control valve 39. This pilot pressure acts on the forward pressure receiving portion 66a of the second drive circuit 32B from the second shuttle valve 42 via the second flow path 47, and at the same time from the third shuttle valve 43 via the third flow path 48 to the first drive. It acts on the reverse pressure receiving portion 66b of the circuit 32A. As a result, the output shaft 57a of the second traveling unit 21R rotates in the forward direction and the output shaft 57a of the first traveling unit 21L rotates in the reverse direction, and the track loader 1 turns to the left.

Further, when the traveling lever 40 is tilted in the oblique direction, the first traveling portion 21L and the first traveling portion 21L and the rear traveling pressure receiving portion 66b of the first drive circuits 32A and 32B are acted on by the differential pressure of the pilot pressure acting on the first traveling portion 21L and The rotation direction and rotation speed of the output shaft 57a of the second traveling unit 21R are determined, and the track loader 1 turns right or left while moving forward or backward.
That is, when the traveling lever 40 is tilted to the left front side, the track loader 1 turns left while moving forward at a speed corresponding to the tilt angle of the traveling lever 40. When the traveling lever 40 is tilted forward to the right, the truck loader 1 turns right while moving forward at a speed corresponding to the tilt angle of the traveling lever 40. When the traveling lever 40 is tilted rearward to the left, the truck loader 1 turns left while moving backward at a speed corresponding to the tilting angle of the traveling lever 40. When the traveling lever 40 is tilted rearward to the right, the truck loader 1 turns right while moving backward at a speed corresponding to the tilting angle of the traveling lever 40.

Next, the hydraulic system of the working system will be described.
As shown in FIG. 2, a discharge oil passage 100e is connected to the first hydraulic pump P1. A plurality of control valves 70 are connected to the discharge oil passage 100e. The plurality of control valves 70 are a boom control valve 70A, a bucket control valve 70B, and a preliminary control valve 70C. The boom control valve 70A is a valve that controls the lift cylinder 26, the bucket control valve 70B is a valve that controls the tilt cylinder 28, and the preliminary control valve 70C is a valve that controls the hydraulic actuator of the preliminary attachment. is there. In the working hydraulic system, the lift cylinder 26, the tilt cylinder 28, the hydraulic actuator of the preliminary attachment, and the like are hydraulic devices.

The operation of the boom 22 and the bucket 23 can be performed by the operation member 71 provided around the driver's seat 13. The operation member 71 is supported so as to be tiltable in the front-rear direction, the width direction orthogonal to the front-rear direction, and the oblique direction from the neutral position. By tilting the operation member 71, the remote control valves 72A, 72B, 72C, 72D provided on the lower portion of the operation member 71 can be operated.

When the operating member 71 is tilted forward, the remote control valve 72A is operated and the pilot pressure is output from the remote control valve 72A. The pilot pressure acts on the pressure receiving portion of the boom control valve 70A, and the working oil that has entered the boom control valve 70A is supplied to the rod side of the lift cylinder 26, whereby the boom 22 descends.
When the operation member 71 is tilted rearward, the remote control valve 72B is operated and the pilot pressure is output from the remote control valve 72B. This pilot pressure acts on the pressure receiving portion of the boom control valve 70A, and the working oil that has entered the boom control valve 70A is supplied to the bottom side of the lift cylinder 26, whereby the boom 22 rises.

That is, the boom control valve 70A is connected to the lift cylinder 26 according to the pressure of the hydraulic oil set by the operation of the operation member 71 (the pilot pressure set by the remote control valve 72A, the pilot pressure set by the remote control valve 72B). It is possible to control the flow rate of flowing hydraulic oil.
When the operating member 71 is tilted to the right, the remote control valve 72C is operated and the pilot oil acts on the pressure receiving portion of the bucket control valve 70B. As a result, the bucket control valve 70B operates in the direction in which the tilt cylinder 28 is extended, and the bucket 23 dumps at a speed proportional to the tilt amount of the operating member 71.

When the operating member 71 is tilted to the left, the remote control valve 72D is operated and the pilot oil acts on the pressure receiving portion of the bucket control valve 70B. As a result, the bucket control valve 70B operates in a direction to reduce the tilt cylinder 28, and the bucket 23 squeezes at a speed proportional to the tilt amount of the operation member 71.
That is, the bucket control valve 70B controls the tilt cylinder 28 according to the pressure of the hydraulic oil set by the operation of the operating member 71 (the pilot pressure set by the remote control valve 72C, the pilot pressure set by the remote control valve 72D). It is possible to control the flow rate of flowing hydraulic oil. That is, the remote control valves 72A, 72B, 72C, 72D change the pressure of the hydraulic oil according to the operation of the operating member 71, and supply the changed hydraulic oil to the boom control valve 70A and the bucket control valve 70B.

The operation of the preliminary control valve 70C is performed by the first electromagnetic valve 73A and the second electromagnetic valve 73B. When the first solenoid valve 73A opens, the pilot oil acts on one pressure receiving portion of the preliminary control valve 70C. Further, when the second solenoid valve 73B is opened, the pilot oil acts on the other pressure receiving portion of the preliminary control valve 70C. Therefore, when pilot oil acts on one pressure receiving portion or the other pressure receiving portion of the preliminary control valve 70C, the preliminary control valve 70C switches, and the preliminary actuator of the preliminary attachment operates by the hydraulic oil supplied from the preliminary control valve 70C. . The operation of the first electromagnetic valve 73A and the second electromagnetic valve 73B is performed by the second control device 82 described later.

As shown in FIGS. 1 and 2, the truck loader (working machine) 1 includes a control device that controls the working machine. The control device includes a first control device 81 and a second control device 82. Although the second controller 82 is shown in FIGS. 1 and 2, the second controller 82 shown in FIG. 1 and the second controller 82 shown in FIG. 2 are the same.
The first control device 81 is a control device that controls the prime mover 29. When the prime mover 29 is an engine, the first control device 81 is an engine control device. For convenience of explanation, it is assumed that the prime mover 29 is an engine.

A setting member 83 is connected to the first control device 81. The setting member 83 is a device that sets (commands) a target rotation speed (target engine rotation speed) of the engine (motor) 29. The setting member 83 has a pedal portion 83a and a sensor 83b that detects an operation amount of the pedal portion 83a. The pedal portion 83a is an accelerator lever that is swingably supported, or an accelerator pedal that is swingably supported. The operation amount detected by the sensor 83b is input to the first control device 81. The engine speed corresponding to the operation amount detected by the sensor 83b is the target engine speed. In other words, the target engine speed is set (determined) based on the operation amount of the setting member 83. The engine 29 is controlled by the first control device 81 so that the determined target engine speed is reached. Further, the first control device 81 is connected with a sensor 84 that detects an actual engine speed (referred to as an actual engine speed), and the actual engine speed is input.

The engine control of the first control device 81 is general, and outputs, for example, a control signal indicating the fuel injection amount, injection timing, and fuel injection rate to the injector. The first control device 81 also outputs a signal indicating the fuel injection pressure and the like to the supply pump and the common rail. That is, the first control device 81 controls the injector, the supply pump, and the common rail so that the actual rotation speed of the engine becomes the target rotation speed of the engine set by the setting member 83.

The second control device 82 is a control device that controls the hydraulic system. The second control device 82 controls, for example, the first electromagnetic valve 73A and the second electromagnetic valve 73B. A switch 74 (see FIG. 2) provided around the driver's seat 13 is connected to the second control device 82. The switch 74 is constituted by, for example, a swingable seesaw type switch, a slidable slide type switch, or a pushable push type switch. The operation of the switch 74 is input to the second control device 82. By operating the switch 74, the first solenoid valve 73A or the second solenoid valve 73B is opened and closed. Therefore, the auxiliary actuator can be operated under the control of the second control device 82.

In addition, the second control device 82 includes a calculation unit 82a, a storage unit 82b, and a control unit 82c. The calculation unit 82a, the storage unit 82b, and the control unit 82c are configured by programs, electric/electronic circuits, electric/electronic components, and the like incorporated in the second control device 82. Further, the second control device 82 can acquire the actual engine speed and the target engine speed from the first control device 81.

When the engine 29 is loaded, the actual engine speed decreases from the target engine speed. The amount of decrease in the actual rotational speed from the target rotational speed when the engine 29 is loaded (the difference between the target rotational speed of the engine and the actual rotational speed of the engine) is called the engine drop amount. The engine drop amount is calculated by the calculation unit 82a based on the target engine speed determined by the setting member 83 and the actual engine speed detected by the sensor 84. In the present embodiment, the control unit 82c determines that the engine 29 is loaded when the actual engine speed drops (drops) from the target engine speed.

The operation valve 45 is connected to the second control device 82. The operation valve 45 is controllable (changeable in opening) by the control unit 82c. Specifically, the opening degree of the operating valve 45 is changed by a command signal output from the control unit 82c to the solenoid of the operating valve 45, whereby the pressure (pilot pressure) of the operating oil output from the operating valve 45 is changed. It can be changed. The storage unit 82b stores control characteristics (a first control characteristic L1 and a second control characteristic L2 described later) for controlling the actuation valve 45. The control unit 82b controls the operation valve 45 based on the control characteristics stored in the storage unit 82b.

By the way, the driver of the work implement 1 feels that the engine 29 is operating sufficiently because the engine speed decreases while the work implement 1 is under load. Therefore, if the engine speed does not decrease even though the work machine 1 is under load, the driver may be suspicious that the engine 29 is not operating sufficiently.
On the other hand, if the engine drop amount is large, engine stall occurs.

The second control device 82 performs control (anti-stall control) for preventing engine stall while making the driver feel a drop in engine speed (the driver's sensation that the engine speed is decreasing). .. In addition, the second control device 82 performs anti-stall control (prevents engine stall) by changing the opening degree of the operation valve 45 based on the drop amount of the engine.

The anti-stall control will be described below with reference to FIGS. 3 and 4.
FIG. 3 is a characteristic diagram showing the first embodiment of the anti-stall control. FIG. 4 is a characteristic diagram showing a second embodiment of the anti-stall control. 3 and 4 show the relationship among the engine speed, the traveling primary pressure, the plurality of first control characteristics L1 and the second control characteristics L2. 3 and 4, the horizontal axis represents the engine speed (actual engine speed), and the engine speed increases toward the right. The vertical axis represents the traveling primary pressure, and the pressure increases as it goes up.

The traveling primary pressure is the pressure of the hydraulic oil in the oil passage from the operation valve 45 to the remote control valve (remote control valves 36, 37, 38, 39) in the second oil supply/discharge passage 100c. That is, it is the pressure (pilot pressure) of the operating oil output from the operating valve 45, and is the primary pressure of the operating oil that enters the remote control valves 36 to 39 provided on the traveling lever 40 that performs the traveling operation.
First, a first embodiment of the anti-stall control will be described with reference to FIG.

The plurality of first control characteristics L1 are characteristics indicating the relationship between the running primary pressure and the actual engine speed when the load of the engine 29 is above a predetermined value (when the amount of drop of the engine is above a predetermined number). is there. The first control characteristic L1 is provided corresponding to the target engine speed. That is, the first control characteristic L1 exists for each target engine speed.
The second control characteristic L2 is a characteristic that indicates the relationship between the running primary pressure and the actual engine speed when the load of the engine 29 is less than the predetermined value (when the engine drop amount is the rotation number that is less than the predetermined value). The second control characteristic L2 is a characteristic line common to all target rotation speeds. Therefore, the second control characteristic L2 is one.

The plurality of first control characteristics L1 and second control characteristics L2 are stored in the storage unit 82a of the second control device 82 (data indicating the first control characteristics L1 and the second control characteristics L2, or a function or the like). The storage unit 82a has control parameters and the like).
The control unit 82c of the second control device 82 has a determination value for determining the engine drop amount (the amount of decrease in the actual rotation speed from the target rotation speed) for each target rotation speed. When the engine drop amount is less than the predetermined determination value, the control unit 82c controls the actuation valve 45 based on the second control characteristic L2. That is, when the amount of drop of the engine is less than the predetermined value, the controller 82c adjusts the opening degree of the proportional valve 45 so that the relationship between the actual engine speed and the traveling primary pressure matches the second control characteristic L2. (The opening degree of the operating valve 45 is adjusted by the controller 82c so that the traveling primary pressure corresponding to the actual rotation speed determined by the second control characteristic L2 is output from the operating valve 45).

When the engine drop amount is equal to or greater than the predetermined determination value, the control unit 82c determines the second control characteristic L1 corresponding to the target rotation speed set by the setting member 83 (second The operation valve 45 is controlled by switching from the control characteristic L2 to the first control characteristic L1. That is, when the amount of drop of the engine is equal to or greater than the predetermined value, the controller 82c adjusts the opening degree of the proportional valve 45 so that the relationship between the actual engine speed and the traveling primary pressure matches the first control characteristic L1. (The opening of the actuation valve 45 is adjusted by the controller 82c so that the traveling primary pressure corresponding to the actual rotation speed determined by the first control characteristic L1 is output from the actuation valve 45).

In FIG. 3 (first embodiment), four control characteristics, that is, a first control characteristic L1a, a first control characteristic L1b, a first control characteristic L1c, and a first control characteristic L1d are set as the plurality of first control characteristics L1. It is illustrated. The first control characteristic L1a is a characteristic when the target rotation speed is M1 rpm. The first control characteristic L1b is a characteristic when the target rotation speed is M2 rpm, which is lower than M1 rpm. The first control characteristic L1c is a characteristic when the target rotation speed is M3 rpm, which is lower than M2 rpm. The first control characteristic L1d is a characteristic when the target rotation speed is M4 rpm, which is lower than M3 rpm.

Next, the first control characteristic L1a, the first control characteristic L1b, the first control characteristic L1c, and the first control characteristic L1d will be described in detail.
In the present embodiment, the first control characteristic L1a, the first control characteristic L1b, the first control characteristic L1c, and the first control characteristic L1d are linear and have the same inclination.
The first control characteristic L1a is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point A1a on the second control characteristic L2. The point A1a is a point at which the actual engine speed has decreased from the target speed M1 rpm by the drop amount X1a (a point on the second control characteristic L2 when the drop amount from the target speed M1 rpm is X1a). The first control characteristic L1b is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point A1b on the second control characteristic L2. A point A1b is a point where the actual engine speed is reduced from the target engine speed M2 rpm by the drop amount X1b. The first control characteristic L1c is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point A1c on the second control characteristic L2. A point A1c is a point where the actual engine speed is reduced from the target engine speed M3 rpm by the drop amount X1c. The first control characteristic L1d is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point A1d on the second control characteristic L2. A point A1d is a point where the actual engine speed decreases by the drop amount X1d from the target engine speed M4 rpm.

The drop amount X1b has a smaller value than the drop amount X1a. The drop amount X1c has a smaller value than the drop amount X1b. The drop amount X1d has a smaller value than the drop amount X1c. For example, when the target engine speed is 2800 rpm, the determination value of the drop amount X1 until the switching from the second control characteristic L2 to the first control characteristic L1 is 300 rpm. The determination value is 200 rpm when the target engine speed is 2600 rpm, and the determination value is 100 rpm when the engine target speed is 2400 rpm and the determination value is 50 rpm when the engine speed is 2300 rpm or less. When a plurality of judgment values are set, the smallest judgment value may be zero.

Therefore, the drop amount X1 from when the second control characteristic L2 is switched to the first control characteristic L1 is set so that the value increases as the target engine speed increases. In other words, the control unit 82c has a determination value that is set to a larger value as the target rotation speed increases. The control unit 82c controls the operation valve 45 using the determination value that is set to a larger value as the target rotation speed increases.

The first control characteristic L1a, the first control characteristic L1b, the first control characteristic L1c, and the first control characteristic L1d follow the third characteristic L3. The third characteristic L3 is a characteristic line in which the traveling primary pressure drops as the engine speed decreases, and is a linear characteristic line. The slope of the third characteristic L3 is smaller than that of the first control characteristic line L1 (first control characteristic L1a, first control characteristic L1b, first control characteristic L1c, and first control characteristic L1d).

Next, the relationship between the first control characteristic L1 and the third characteristic L3 will be described.
The first control characteristic L1a is connected to the third characteristic L3 at the first engine speed D1 at which the actual engine speed is a predetermined value. The first control characteristic L1b is connected to the third characteristic L3 at the second rotation speed D2 at which the actual rotation speed of the engine is lower than the first rotation speed D1. The first control characteristic L1c is connected to the third characteristic L3 at the third rotation speed D3 where the actual rotation speed of the engine is lower than the second rotation speed D2. The first control characteristic L1d is connected to the third characteristic L3 at a fourth rotation speed D4 at which the actual rotation speed of the engine is lower than the third rotation speed D3. The first control characteristic L1a, the first control characteristic L1b, the first control characteristic L1c, and the first control characteristic L1d follow the common third characteristic L3.

Next, the control by the control unit 82c will be described.
As shown in FIG. 3, when the load on the engine 29 is less than a predetermined value, that is, when the actual engine speed does not exceed the target drop speed by a predetermined drop amount, the control unit 82c sets the second control characteristic L2. The opening degree of the operating valve 45 is controlled so that the actual engine speed shown and the pressure output from the operating valve 45 (the pressure of the hydraulic oil entering the remote control valves 36 to 39) match.
Here, when the target rotation speed of the engine is M1 and the actual rotation speed of the engine drops from the target rotation speed M1 by the drop amount X1a or more (below the point A1a), the control unit 82c changes the second control characteristic L2 from the second control characteristic L2. Switch to 1 control characteristic L1a. Then, the control unit 82c controls the opening degree of the actuation valve 45 so that the actual engine speed indicated by the first control characteristic L1a and the pressure output from the actuation valve 45 match. Further, when the operating valve 45 is controlled by the first control characteristic L1a, when the actual engine speed becomes equal to or lower than the first rotational speed D1, the operating valve 45 is controlled according to the third control characteristic L3.

When the target rotation speed of the engine is M2 and the actual rotation speed of the engine drops from the target rotation speed M2 by the drop amount X1b or more (below the point A1b), the control unit 82c causes the second control characteristic L2 to the first control characteristic. Switch to L1b. Then, the control unit 82c controls the opening degree of the operating valve 45 so that the actual engine speed indicated by the first control characteristic L1b and the pressure output from the operating valve 45 match. Further, when the operating valve 45 is controlled with the first control characteristic L1b, when the actual engine speed becomes equal to or lower than the second rotational speed D2, the operating valve 45 is controlled according to the third control characteristic L3.

When the target rotation speed of the engine is M3 and the actual rotation speed of the engine decreases from the target rotation speed M3 by the drop amount X1c or more (below the point A1c), the control unit 82c causes the second control characteristic L2 to the first control characteristic. Switch to L1c. Then, the control unit 82c controls the opening degree of the actuation valve 45 so that the actual engine speed indicated by the first control characteristic L1c and the pressure output from the actuation valve 45 match. Further, when the operating valve 45 is controlled by the first control characteristic L1c, when the actual engine speed becomes equal to or lower than the third rotational speed D3, the operating valve 45 is controlled according to the third control characteristic L3.

When the target rotation speed of the engine is M4 and the actual rotation speed of the engine decreases from the target rotation speed M4 by the drop amount X1d or more (below the point A1d), the control unit 82c causes the second control characteristic L2 to the first control characteristic. Switch to L1d. Then, the control unit 82c controls the opening degree of the operation valve 45 so that the actual rotation speed of the engine indicated by the first control characteristic L1d and the pressure output from the operation valve 45 match. Further, when the actuation valve 45 is controlled by the first control characteristic L1d, when the actual engine speed becomes equal to or lower than the fourth speed D4, the actuation valve 45 is controlled according to the third control characteristic L3.

According to the above, in the second control characteristic L2, the degree of decrease in the traveling primary pressure due to the decrease in the actual engine speed is slower than that in the first control characteristic L1. Therefore, with the second control characteristic L2, the suppression force against the decrease in the actual engine speed when the engine 29 is loaded (the actual engine speed decreases in response to the load). As a result, when a load is applied to the engine 29, the driver can feel a drop in engine speed (that the engine 29 is operating sufficiently).

Further, with the first control characteristic L1, the traveling primary pressure for a predetermined engine speed is lower than the traveling primary pressure with the second control characteristic L2. That is, when focusing on the same engine speed, the traveling primary pressure of the first control characteristic L1 is lower than the traveling primary pressure of the second control characteristic L2. Therefore, the control based on the first control characteristic L1 suppresses the pressure (pilot pressure) of the hydraulic oil entering the remote control valve, as compared with the control based on the second control characteristic L2. By adjusting the swash plate angle of the traveling pump (traveling hydraulic pump) 66 with the hydraulic oil suppressed to be low, the load acting on the engine 29 is effectively reduced, and the engine speed is effectively reduced. It can be suppressed (the engine speed can be maintained higher than that of the control based on the second control characteristic L2). This makes it possible to effectively prevent engine stall when the load on the engine 29 becomes larger than a predetermined value and the decrease in engine speed becomes large.

As described above, it is possible to achieve both the feeling of the driver when the load is applied to the engine 29 and the prevention of the engine stall.
Further, when the drop amount until the switching from the second control characteristic L2 to the first control characteristic L1 is the same for all target rotation speeds, if the drop amount is adjusted to a high target rotation speed, the target rotation speed is The smaller the value, the higher the possibility of causing engine stall due to the decrease in engine speed. On the other hand, in the first embodiment, the drop amount X1 from when the second control characteristic L2 is switched to the first control characteristic L1 is smaller when the target rotation speed is lower than when the target rotation speed is high. I am trying. As a result, both the driver's feeling and the prevention of engine stall can be achieved in accordance with the target engine speed.

The relationship between the target engine speed and the drop amount X1 may be a proportional relationship in which the drop amount X1 increases proportionally as the engine target speed continuously or stepwise increases. As for the relationship between the target engine speed and the drop amount X1, a threshold value may be set for the target engine speed, and the drop amount may be switched by this threshold value (the drop amount before and after the threshold value is different).

On the other hand, when the actual engine speed drops below the first to fourth engine speeds D1 to D4, the pressure of the hydraulic oil entering the remote control valves 36 to 39 is controlled by the control based on the third control characteristic L3. ..
For example, when the working machine 1 is moved forward and the bucket 23 is plunged into piles of sand or the like, the actual engine speed drops greatly, but when the actual engine speed drops significantly, If the gradient of the first control characteristic L1 is large (the amount of drop of the traveling primary side pressure with respect to the amount of drop is large), the torque of the engine 29 is insufficient and the actual engine speed returns slowly. Therefore, the slope of the third control characteristic L3, which is the region where the drop amount in the first control characteristic L1 is excessive, is made gentler than the slope of the first control characteristic L1 (the decrease amount of the traveling primary pressure with respect to the drop amount is reduced). This makes it easier for the actual engine speed to return after the engine speed has dropped extremely large. can do.

The drop amount X1 may be switched by the driver's operation. That is, the first control characteristic L1 of the pattern illustrated in FIG. 3 is different from the first control characteristic of the other pattern, and the drop amount X1 is different (the numerical value is larger than the drop amount X1 shown in FIG. The other pattern of the reduced first control characteristic is stored in the storage unit 82b. Further, as shown in FIG. 1, a switch (referred to as a changeover switch) 110 connected to the second control device 82 is provided, and the changeover switch 110 is arranged at a place where the driver can operate (for example, around the driver's seat 13). To do. The changeover switch 110 is configured to switch between the first control characteristic of the pattern shown in FIG. 3 and the first control characteristic of another pattern. This makes it possible to select the first control characteristic of the pattern according to the work situation or the like. The pattern of the first control characteristic that can be switched may be two patterns or three or more patterns.

In addition, another switch (referred to as a setting switch) 111 connected to the second control device 82 is provided, and the setting switch 111 is arranged around the driver's seat 13. With this setting switch 111, the judgment value can be set arbitrarily.
Further, the switching of the pattern of the first control characteristic may be automatically performed by switching the shift (traveling speed) of the traveling motor 57 (switching between the first speed and the second speed). For example, the changeover switch 110 is configured by a changeover valve that is switched by the pilot pressure that switches the first hydraulic pressure changeover valve 63. Then, in conjunction with the switching of the first hydraulic pressure switching valve 63, the pattern of the first control characteristic is automatically switched. Further, the pattern of the first control characteristic may be automatically switched by switching the shift of the traveling motor 57 provided with the shift pattern of the third speed or higher.

Further, the switching of the pattern of the first control characteristic may be automatically switched depending on the type of the attachment mounted (mounted). The attached attachment may be automatically identified by a sensor when attached to the work machine 1. Further, the driver may select and switch the pattern of the first control characteristic corresponding to the attached attachment.

[Second Embodiment]
FIG. 4 is a diagram showing the relationship between the engine speed and the traveling primary pressure in the second embodiment.
Regarding the second example, the difference from the first embodiment will be described, and the description of the parts having the same configuration will be omitted.
First, the outline of the second embodiment will be described.

The second embodiment has a plurality of first control characteristics L1 having different inclinations determined corresponding to the target engine speed. The storage unit 82b stores a plurality of first control characteristics L1 having different inclinations. When the load on the engine 29 is equal to or greater than the predetermined value, the control unit 82c controls the actuation valve 45 based on the plurality of first control characteristics L1 having different inclinations determined according to the target engine speed. The slope of the first control characteristic L1 is set to be smaller as the target engine speed of the engine increases. The operation valve 45 is controlled using the first control characteristic L1 in which the inclination is set smaller as the target engine speed increases.

Next, the first control characteristic L1 of the second embodiment will be described in detail.
As shown in FIG. 4, the first control characteristic L1a is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point B1a on the second control characteristic L2. The point B1a is a point on the second control characteristic L2 and corresponds to the target rotation speed M1. The first control characteristic L1b is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point B1b on the second control characteristic L2. The point B1b is a point on the second control characteristic L2 and corresponds to the target rotation speed M2. The first control characteristic L1c is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point B1c on the second control characteristic L2. The point B1c is a point on the second control characteristic L2 and corresponds to the target rotation speed M3. The first control characteristic L1d is a characteristic line in which the traveling primary pressure drops as the engine speed decreases from the point B1d on the second control characteristic L2. The point B1d is a point on the second control characteristic L2 and corresponds to the target rotation speed M4.

The engine stall due to the decrease in the actual engine speed occurs with a smaller drop amount as the target speed decreases (a lower drop amount occurs in the low target speed region than in the high target speed region. Engine stall occurs). As in the conventional case, when the inclinations of the first control characteristics provided for each target rotation speed of the engine are all the same, the inclination of the first control characteristics gives the driver a drop feeling in a region where the target rotation speed is high. In addition, if the inclination is set to prevent engine stall, it may be difficult to prevent engine stall in a region where the target rotation speed is low. On the other hand, if it is difficult to give the driver a feeling of drop in the high target speed range by setting the inclination to give the driver a feeling of drop in the low target speed range and prevent engine stall. Occurs.

Therefore, the inclination of the first control characteristic L1 is set so that the inclination becomes smaller (loose) as the target engine speed increases. The operation valve 45 is controlled using the first control characteristic L1 in which the inclination is set smaller as the target engine speed increases. As a result, it is possible to achieve both the driver's feeling when the load is applied to the engine 29 and the prevention of the engine stall.

Further, regarding the relationship between the target engine speed and the inclination of the first control characteristic L1, the inclination of the first control characteristic L1 increases proportionally as the engine target speed continuously or gradually increases. It may be in a proportional relationship. Further, regarding the relationship between the target engine speed and the inclination of the first control characteristic L1, a threshold value is set for the target engine speed, and the inclination of the first control characteristic L1 is switched by this threshold value (the first and second threshold values are set before and after the threshold value). The inclination of the control characteristic L1 may be different).

Further, the slope of the first control characteristic L1 may be switched by the driver's operation. That is, the first control characteristic L1 is different from the first control characteristic L1 of the pattern illustrated in FIG. 4, and the inclination of the first control characteristic L1 is different (greater than the inclination shown in FIG. The other pattern of the reduced first control characteristic is stored in the storage unit 82b. Then, the changeover switch 110 is configured to switch between the first control characteristic of the pattern shown in FIG. 4 and the first control characteristic of another pattern. This makes it possible to select the first control characteristic of the pattern according to the work situation or the like. The pattern of the first control characteristic that can be switched may be two patterns or three or more patterns.

Further, the switching of the pattern of the first control characteristic may be automatically performed by switching the shift of the traveling motor 57 as in the first embodiment.
Further, the switching of the pattern of the first control characteristic may be automatically switched depending on the type of attachment to be mounted (mounted), as in the first embodiment.
The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

In the above-described embodiment, the traveling pump 66 is exemplified as the hydraulic device, but any hydraulic device may be used as long as it can be operated by the hydraulic oil output from the operating valve 45.
Further, the control may be performed by combining the first control characteristics shown in FIG. 3 having the same inclination and the first control characteristics shown in FIG. 4 having different inclinations. The storage unit 82b has first control characteristics (first control characteristics shown in FIG. 3) having the same inclination and parallel to each other, and first control characteristics (first control characteristics shown in FIG. 4) having different inclinations with respect to the parallel first control characteristics. 1 control characteristic). That is, the storage unit 82b stores both the first control characteristic shown in FIG. 3 and the first control characteristic shown in FIG. The control unit 82c controls the operation valve 45 based on the second control characteristic when the amount of decrease in the actual rotation speed from the target rotation speed is less than the predetermined determination value. Further, when the amount of decrease is equal to or larger than the determination value of the actual rotation speed, the control unit 82c determines the first control characteristic (the first control characteristic having the same slope or the parallel first control characteristics or the slope different from each other). The operation valve 45 is controlled based on the first control characteristic). The control of the actuation valve 45 in the control unit 82c is the same as in the above-described embodiment.

Further, the actuation valve 45 is a valve that supplies the traveling primary pressure to the traveling operation device 14 that operates the traveling pump 66, but is not limited to this. For example, an electromagnetic proportional valve that supplies control hydraulic oil (servo pressure) to a servo regulator that controls the swash plate of the traveling pump 66 may be used as the operation valve. In this case, the actuation valve (electromagnetic proportional valve) operates in conjunction with the operation of the travel lever 40 of the travel operation device 14. For example, when the traveling lever 40 is not operated and is in the neutral position, the output of the operating valve is zero. When the traveling lever 40 is operated to the maximum (maximum operation), the pressure corresponding to the traveling primary pressure is output as shown in FIGS. 3 and 4. The actuating valve outputs pressure by making the traveling primary pressure correspond to the operation amount of the traveling lever. For example, when the traveling primary pressure is 2.5 MPa, the actuating valve outputs a value obtained by evenly assigning 2.5 MPa to the operation amount (0% to 100%) of the traveling lever 40. In this case, when the operation amount of the traveling lever 40 is the maximum operation (100%), the operating valve outputs 2.5 MPa corresponding to the maximum operation, and when the operation amount is half (50%). Output 1.25 MPa corresponding to half. When the traveling primary pressure is 1.0 MPa, the operating valve outputs a value obtained by assigning the traveling pressure of 1.0 MPa to the operation amount (0% to 100%) of the traveling lever 40. Further, after setting the traveling primary pressure corresponding to the maximum operation amount of the traveling lever 40 in advance, the traveling primary pressure is assigned to the range from the maximum operation amount to the minimum operation amount (the relationship between the operation amount and the traveling primary pressure). Is constant). When the travel lever 40 is operated and the travel primary pressure obtained by the operation amount of the operation lever 40 does not exceed the travel primary pressure corresponding to the actual engine speed, it is obtained by the operation amount of the operation lever 40. Apply the running primary pressure. On the other hand, when the traveling primary pressure obtained by the operation amount of the operation lever 40 exceeds the traveling primary pressure corresponding to the actual engine speed, the traveling primary pressure corresponding to the actual engine speed is adopted. That is, the relationship between the operation amount of the travel lever 40 and the travel primary pressure is set in advance, and control is performed so as not to exceed the travel primary pressure based on the operation amount.

When the travel primary pressure is assigned to the operation amount of the travel lever 40, it may be assigned in consideration of the play of the travel lever 40. Further, the allocation of the traveling primary pressure to the operation amount of the traveling lever 40 does not have to be evenly allocated. Further, the relationship between the traveling primary pressure and the traveling lever 40 may not be proportional.

1 Working machine (truck loader)
29 Engine (engine)
45 Actuating valve 57 Travel motor (hydraulic equipment)
66 Traveling pump (hydraulic equipment)
82b Storage part 82c Control part 83 Setting member P2 2nd hydraulic pump

Claims (7)

A prime mover,
A setting member for setting a target speed of the prime mover,
A hydraulic pump that is operable by driving the prime mover and discharges hydraulic oil;
An operating valve to which hydraulic oil discharged from the hydraulic pump is supplied,
A hydraulic device operable by the hydraulic oil of the operating valve,
A plurality of first characteristics which are characteristics showing the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotation speed of the prime mover when the load of the prime mover is equal to or more than a predetermined value, and which have different inclinations determined corresponding to the target rotation speed. A storage unit for storing control characteristics,
When the load of the prime mover is equal to or higher than a predetermined value, a control unit that controls the actuating valve based on the first control characteristics having different inclinations determined according to the target rotation speed,
Is equipped with a hydraulic system for work equipment. The hydraulic system for a working machine according to claim 1, wherein the control unit controls the actuating valve by using a first control characteristic in which an inclination is set smaller as the target rotation speed increases. The hydraulic system for a working machine according to claim 1, further comprising a switch capable of changing the first control characteristic. The hydraulic system for a work machine according to claim 1, further comprising a switch capable of changing the determination value. A prime mover,
A setting member for setting a target speed of the prime mover,
A hydraulic pump that is operable by driving the prime mover and discharges hydraulic oil;
An operating valve to which hydraulic oil discharged from the hydraulic pump is supplied,
A hydraulic device operable by the hydraulic oil of the operating valve,
It is a characteristic showing the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotation speed of the prime mover when the load of the prime mover is equal to or more than a predetermined value, and the inclinations determined corresponding to the target rotation speed are parallel or different in inclination. A storage unit that stores a plurality of first control characteristics and a second control characteristic that indicates the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotation speed of the prime mover when the load of the prime mover is less than a predetermined value;
When the decrease amount of the actual rotation speed from the target rotation speed is less than a predetermined determination value, the operation valve is controlled based on the second control characteristic, and the decrease amount is the actual rotation speed. And a control unit that controls the operating valve based on the first control characteristic that is determined according to the target rotation speed,
Is equipped with a hydraulic system of the working machine. A prime mover,
A setting member for setting a target speed of the prime mover,
A hydraulic pump that is operable by driving the prime mover and discharges hydraulic oil;
An operating valve to which hydraulic oil discharged from the hydraulic pump is supplied,
A hydraulic device operable by the hydraulic oil of the operating valve,
A storage unit that stores a plurality of first control characteristics that are characteristics indicating the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotation speed of the prime mover, and that have different inclinations that are determined corresponding to the target rotation speed,
When the amount of decrease in the actual rotation speed from the target rotation speed is equal to or more than a predetermined determination value, the operation is performed based on the first control characteristic having a different inclination determined according to the target rotation speed. A control unit for controlling the valve,
Is equipped with a hydraulic system of the working machine. A prime mover,
A setting member for setting a target speed of the prime mover,
A hydraulic pump that is operable by driving the prime mover and discharges hydraulic oil;
An operating valve to which hydraulic oil discharged from the hydraulic pump is supplied,
A hydraulic device operable by the hydraulic oil of the operating valve,
A plurality of first control characteristics which are characteristics showing a relationship between the pressure of the hydraulic oil of the operation valve and an actual rotation speed of a prime mover, and the inclinations corresponding to the target rotation speed are parallel or different in inclination; A storage unit that stores a second control characteristic indicating the relationship between the pressure of the hydraulic oil of the operating valve and the actual rotational speed of the prime mover;
When the decrease amount of the actual rotation speed from the target rotation speed is less than a predetermined determination value, the operation valve is controlled based on the second control characteristic, and the decrease amount is the actual rotation speed. And a control unit that controls the operating valve based on the first control characteristic that is determined according to the target rotation speed,
Is equipped with a hydraulic system for work equipment.

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