JP2003184134A - Control method and controller for hydraulic pump for work machine of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic pump capacity controller for a working vehicle capable of definitely detecting excavating work being performed and of reducing power loss. <P>SOLUTION: A driving force detecting means (51), a bottom pressure detector (45) of a lift cylinder, a hydraulic detector (46) of a tilt cylinder, an operating position detecting means (55) and a capacity controller (41) of a variable capacity type hydraulic pump (26) are connected to a controller (50). The controller (50) inputs detected signals from the driving force detecting means (51), the bottom pressure detector (45), the hydraulic detector (46), and operating position detecting means (55); when at least one of the travelling drive force, lift cylinder bottom pressure and tilt cylinder pressure exceeds a predetermined value and exceeds the predetermined time, the excavation work is judged to be in progress, and a control for reducing the capacity of the variable capacity type hydraulic pump (26) to the predetermined capacity less than the maximum capacity is carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement control method and a control device for a hydraulic pump for a work vehicle of a work vehicle, particularly a civil work vehicle.

[0002]

2. Description of the Related Art For example, in a hydraulic system for driving a working machine of a wheel loader, which is a civil engineering work vehicle, hydraulic pressure is required at the time of excavation work, but the discharge amount may be small. In such a case, if a fixed displacement hydraulic pump is used, a large amount of pressure oil will be returned to the tank, resulting in a great power loss. In order to reduce this power loss, a method has been proposed in which the hydraulic pump is of a variable displacement type and the pump discharge amount is reduced during excavation work. As an example, U.S.P. S. Patent Number 6,07
There is one disclosed in 3,442. According to this
Work is performed when at least one of the following conditions is satisfied: 1, the transmission is in the forward first speed stage position, 2, the work implement is in the excavation position, 3, and the vehicle traveling speed is less than or equal to the set speed. It is determined that the vehicle is under excavation work, and the pump capacity is controlled to be reduced to a predetermined capacity equal to or less than the maximum capacity. Among the above, the excavation position of the working machine is defined as shown in FIG. FIG. 9 is a side view of the work implement 70 in the excavation position. In FIG. 9, a base end portion of a lift arm 72 is swingably attached to a vehicle body 71 by an arm pin 73, and the vehicle body 71 and the lift arm 72 are connected by a lift cylinder 74. When the lift cylinder 74 is expanded or contracted, the lift arm 72 moves to the arm pin 7.
Swing about 3. A bucket 75 is swingably attached to a tip end portion of the lift arm 72 by a bucket pin 76, and the vehicle body 71 and the bucket 75 are connected via a tilt cylinder 77 and a link device 78.
When the tilt cylinder 77 is expanded or contracted, the bucket 75 swings around the bucket pin 76. The excavation position of the working machine 70 is a line Y- connecting the arm pin 73 and the bucket pin 76.
The reference position of Y is defined, and when the lift arm 72 is located below that, it is defined as the excavation position.

[0003]

However, the above method has the following problems. First, when the transmission is in the first forward speed, the pump capacity is reduced to a predetermined capacity equal to or less than the maximum capacity. However, in this case, the excavation work is not always performed,
There may be a case where the vehicle is approaching a predetermined place at the first forward speed while operating the work machine. In such a case, the speed of the work machine becomes slow, and the work efficiency may decrease. In addition, depending on the soil quality, there are cases where work is performed at the second forward speed, and at that time, the pump capacity is not reduced and power loss occurs.
Secondly, when the work implement is at the excavation position, the pump capacity is reduced to a predetermined capacity equal to or less than the maximum capacity, but the lift arm may excavate at a position higher than the reference position. In such a case, the pump capacity is not reduced and the power loss cannot be reduced. Thirdly, when the vehicle traveling speed is equal to or lower than the set speed, the pump capacity is reduced to a predetermined capacity equal to or less than the maximum capacity, but the excavation work is not performed and the working machine is operated toward the destination. It may move at a speed less than the set speed. Even in such a case, the pump capacity may be reduced, the speed of the working machine may be slowed, and the working efficiency may be lowered. Fourth, when the transmission is the first forward speed, the work implement is at the excavation position, and the vehicle traveling speed is equal to or lower than the set speed, the pump displacement is reduced to a predetermined displacement equal to or lower than the maximum displacement. At the time of normal excavation, the bucket is slightly floated from the ground to prevent the traveling resistance from increasing due to the grounding of the bucket until immediately before the object, and the bucket is grounded immediately before it plunges into the object. In that case, there is a problem that the response speed of the work machine becomes slow, the operation is delayed, and the worker feels uncomfortable.

The present invention has been made in view of the above problems, and after surely detecting that the work vehicle is in the excavation work state, the pump capacity is reduced to reduce the power loss and the work efficiency. It is an object of the present invention to provide a control method and a control device for a hydraulic pump for a working machine of a work vehicle, which does not reduce the workability or make the operator feel uncomfortable.

[0005]

In order to achieve the above-mentioned object, a first invention is a method for controlling a hydraulic pump for a working machine of a working vehicle, wherein the working vehicle operates the working machine. A lift cylinder and a tilt cylinder,
A hydraulic pump that supplies a predetermined amount of pressure oil to the lift cylinder and the tilt cylinder, and a vehicle driving force and / or an oil pressure on the bottom side of the lift cylinder and / or an oil pressure of the tilt cylinder have a predetermined value. When it is determined that the excavation work is being performed, it is determined that the capacity of the hydraulic pump is reduced to a predetermined capacity equal to or less than the maximum capacity, and then control for reducing the capacity of the hydraulic pump to a predetermined capacity is performed. I'm trying to do it.

According to the first aspect of the invention, the working vehicle is under excavation work when the running driving force of the vehicle, and / or the bottom side hydraulic pressure of the lift cylinder and / or the hydraulic pressure of the tilt cylinder exceeds a predetermined value. Therefore, the control method is to reduce the capacity of the hydraulic pump to a predetermined capacity equal to or less than the maximum capacity. Since the driving force, the bottom cylinder hydraulic pressure of the lift cylinder, and the hydraulic pressure of the tilt cylinder are obviously different between during excavation work and during non-excavation work, it can be reliably determined that excavation work is in progress, and effective power loss reduction Can be done. In addition, since the hydraulic pump capacity is not reduced during non-excavation work, there is no fear of reducing work efficiency or giving a feeling of strangeness to a worker.

A second aspect of the present invention is a method of controlling a hydraulic pump for a working machine of a working vehicle, wherein the working vehicle is provided with a lift cylinder and a tilt cylinder for operating the working machine, and a predetermined pressure oil is supplied to the lift cylinder and the tilt cylinder. And a hydraulic pump for supplying the vehicle, and excavates when the driving force of the vehicle and / or the hydraulic pressure on the bottom side of the lift cylinder and / or the hydraulic pressure of the tilt cylinder exceeds a predetermined value and a predetermined time elapses. It is determined that work is in progress, then the capacity of the hydraulic pump is reduced to a predetermined capacity equal to or less than the maximum capacity, and then control is performed to reduce the capacity of the hydraulic pump to a predetermined capacity.

According to the second aspect of the invention, the working vehicle is operated when the traveling driving force of the vehicle, and / or the bottom side hydraulic pressure of the lift cylinder and / or the hydraulic pressure of the tilt cylinder exceeds a predetermined value and a predetermined time has elapsed. Determines that excavation work is in progress, and uses a control method of reducing the capacity of the hydraulic pump to a predetermined capacity equal to or less than the maximum capacity. The driving force, the hydraulic pressure on the bottom side of the lift cylinder, and the hydraulic pressure on the tilt cylinder are obviously different between during excavation work and during non-excavation work.
Further, since it is confirmed whether those values have passed the predetermined time or more, it can be surely determined that the excavation work is in progress, and effective power loss reduction can be performed. In addition, since the hydraulic pump capacity is not reduced during non-excavation work, there is no fear of reducing work efficiency or giving a feeling of strangeness to a worker.

In a third aspect based on the first or second aspect, the work vehicle is provided with a forward / backward operating means, and when the forward / backward operating means changes from a forward drive to a neutral or reverse drive position, excavation work is completed. Therefore, the control for reducing the capacity of the hydraulic pump to a predetermined capacity is stopped.

According to the third aspect of the invention, when the operator moves the forward / backward operating means from the forward position to the neutral position or the reverse position, it is judged that the excavation work is completed, and the pump displacement reduction control is stopped. Therefore, the determination of the end of the excavation work becomes reliable, and the operation speed of the work machine increases after the end of the excavation work, and there is no fear that workability will deteriorate.

According to a fourth aspect of the present invention, in a control device for a hydraulic pump for a working machine of a working vehicle, the working vehicle is provided with a lift cylinder and a tilt cylinder for operating the working machine, and a predetermined pressure oil is supplied to the lift cylinder and the tilt cylinder. A variable displacement hydraulic pump for supplying the variable displacement hydraulic pump, wherein the control device includes a driving force detecting means for detecting a traveling driving force of the vehicle, a bottom pressure detector for detecting a bottom side hydraulic pressure of the lift cylinder, and the tilt cylinder. A hydraulic pressure detector for detecting the hydraulic pressure of the, a displacement control device for controlling the displacement of the variable displacement hydraulic pump, the driving force detection means, and a bottom pressure detector,
The detected value from the oil pressure detector is input and calculated, and when at least one of the values exceeds a predetermined value and a predetermined time has elapsed, the displacement control device causes the displacement controller to change the displacement of the variable displacement hydraulic pump. And a controller that outputs a capacity control signal for reducing the capacity to a predetermined capacity equal to or less than the maximum capacity.

According to the fourth aspect of the present invention, when at least one of the running driving force of the vehicle, the hydraulic pressure on the bottom side of the lift cylinder, and the hydraulic pressure on the tilt cylinder exceeds a predetermined value and a predetermined time elapses, the hydraulic pump The capacity can be reduced to a predetermined capacity. That is, since it is possible to reliably detect that the work vehicle is under excavation work and reduce the pump capacity to a predetermined capacity, it is possible to effectively reduce power loss and obtain a work vehicle that can work efficiently.

According to a fifth aspect of the present invention, in a control device for a hydraulic pump for a working machine of a working vehicle, the working vehicle is provided with a lift cylinder and a tilt cylinder for operating the working machine, and a predetermined pressure oil is supplied to the lift cylinder and the tilt cylinder. A variable displacement hydraulic pump for supplying, a bottom pressure detector for detecting a bottom side hydraulic pressure of the lift cylinder, a displacement control device for controlling the displacement of the variable displacement hydraulic pump, The detected value from the bottom pressure detector is input and calculated, and when the detected value exceeds a predetermined value and a predetermined time elapses, the capacity control device sets the capacity of the variable displacement hydraulic pump to the maximum capacity. The controller is configured to output a capacity control signal for reducing the capacity to the following predetermined capacity.

According to the fifth aspect of the invention, when the bottom side hydraulic pressure of the lift cylinder exceeds a predetermined value and a predetermined time has elapsed, the capacity of the hydraulic pump can be reduced to a predetermined capacity. That is, since it is possible to reliably detect that the work vehicle is under excavation work and reduce the pump capacity to a predetermined capacity, it is possible to effectively reduce power loss and obtain a work vehicle that can work efficiently.

In a sixth aspect based on the fourth or fifth aspect, the work vehicle comprises a forward / backward operating means, an operating position detecting means for detecting an operating position of the forward / backward operating means, and the operating position detecting means. And a controller for stopping the transmission of the displacement control signal of the variable displacement hydraulic pump output to the displacement control device when the operating position changes from the forward drive to the neutral or reverse drive. .

According to the sixth aspect of the invention, when the forward / backward operating means is in the neutral or reverse position, a displacement control signal for reducing the displacement of the variable displacement hydraulic pump, which is output to the displacement control device, is transmitted. You can stop. Therefore, the end point of the excavation work can be reliably detected, and the pump capacity does not decrease during the non-excavation work. Therefore, there is no fear of lowering work efficiency.

In a seventh invention according to the fourth, fifth or sixth invention, the work vehicle has an articulated structure, and the control device detects a steering refraction angle of the vehicle. And a controller for inputting a detection value of the steering refraction angle detector and stopping transmission of a capacity control signal to be output to the capacity control device when the steering refraction angle exceeds a predetermined angle. There is.

According to the seventh aspect of the invention, when the articulate angle exceeds a predetermined angle, the displacement control of the hydraulic pump is stopped, so that the power consumed by the hydraulic pump is increased, the driving force for driving the vehicle is reduced, and each part of the vehicle is reduced. There is no fear that durability will be reduced due to unreasonable force.

According to an eighth aspect of the present invention, in the fourth, fifth or sixth aspect of the invention, the work vehicle has an articulated structure and is provided with a pair of left and right steering cylinders for steering, and the control device includes the left and right steering cylinders. The oil pressure of the steering cylinder of the steering oil pressure detector for detecting each, and the detection value of the steering oil pressure detector is input,
And a controller for stopping transmission of the capacity control signal output to the capacity control device when the difference between the left and right hydraulic pressures exceeds a predetermined value.

According to the eighth aspect of the present invention, when the difference between the hydraulic pressures of the left and right steering cylinders exceeds a predetermined value, the displacement control of the pump is stopped, so that the power consumed by the hydraulic pump increases and the running drive force of the vehicle is increased. Is reduced, an unreasonable force is not applied to each part of the vehicle, and there is no fear of lowering durability.

In a ninth aspect based on the fourth to eighth aspects, the control device has a manual displacement control means capable of controlling the displacement of the variable displacement hydraulic pump.

According to the ninth aspect of the invention, since the manual displacement control means capable of controlling the pump displacement is provided, when the operator desires to arbitrarily set the pump displacement depending on the soil quality, the desired displacement can be set and the working efficiency is improved. can do.

A tenth invention is the fourth to ninth invention, wherein
The control device is configured to have a displacement control selection means capable of selecting whether or not to perform displacement control of the variable displacement hydraulic pump.

According to the tenth aspect of the invention, since the capacity control selecting means is provided, the driver can select whether or not to control the capacity of the hydraulic pump during excavation work depending on the situation. Therefore, efficient work can be performed.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a control method and a control device for a hydraulic pump for a work machine of a work vehicle according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side view of a wheel loader 1 which is an example of a work vehicle, and FIG. 2 is a plan view. 1 and 2
In the driver's cab 2, engine compartment 3, and rear wheels 4,
A front frame 7 having front wheels 6 and 6 is attached to a front portion of a rear vehicle body 5 having 4 by a center pin 8 so as to be swingable left and right to form an articulate structure.
In FIG. 2, the rear vehicle body 5 and the front frame 7 are connected by a pair of left and right steering cylinders 9 and 9, and the left and right steering cylinders 9 and 9 are expanded and contracted to connect the rear vehicle body 5 and the front frame 7 to a center pin 8 With the center as the center, it swings left and right as shown by the chain double-dashed line to steer. The angle θ in the figure is called the steering refraction angle.

1 and 2, a working machine 10 is attached to the front frame 7. That is, the lift arm 1 whose base end is swingably attached to the front frame 7
A bucket 12 is swingably attached to the tip portion of 1. The front frame 7 and the lift arm 11 are connected by a pair of lift cylinders 13 and 13, and the lift arms 11 are expanded and contracted to expand and contract.
Swings. A substantially central portion of a tilt arm 14 is swingably supported by the lift arm 11, and one end of the tilt arm 14 and the front frame 7 are connected by a tilt cylinder 15. The other end of the tilt arm 14 and the bucket 12 are connected by a tilt rod 16, and when the tilt cylinder 15 is expanded and contracted, the bucket 12 swings.

In FIG. 1, a power unit 2 is attached to the rear vehicle body 5.
0 is installed. The power plant 20 includes an engine 21,
It includes a torque converter 22, a forward / reverse switching, a transmission 23 capable of switching a plurality of shift speeds, a distributor 24, reduction gears 25, 25 for driving the rear wheels 4 and the front wheels 6, and the like. Further, the engine 21 is the lift cylinder 1.
3. The variable displacement hydraulic pump 26 that supplies pressure oil to the tilt cylinder 15 is driven.

In the cab 2, a forward / backward operating means 30
The speed stage selecting means 31 of the transmission 23, the manual displacement control means 32 capable of manually controlling the displacement of the variable displacement hydraulic pump 26, and whether or not the displacement control of the pump is automatically performed can be selected. And a capacity control selection means 33. Each of the above means may be a lever type, a switch type, a dial type, or any other type.

Excavation and loading operations of the wheel loader 1 will be described next. The driver operates the forward / backward operating means 30 to move the vehicle forward, and the speed stage selecting means 31 selects the speed stage of the transmission 23 according to the object. Bucket 12
Is located at the excavation position. Next, the blade edge of the bucket 12 is thrust into the object, and the tilt cylinder is operated to operate the bucket 1
2 is tilted back and the object is scooped into the bucket 12. Next, the lift cylinder 13 is extended to raise the lift arm 11, and the forward / backward operating means 30 is operated while raising the bucket 12 to move the vehicle backward. Next step,
It steers and approaches the dump truck, dumps the bucket 12 at a predetermined position, and loads the object on the bed of the dump truck.

FIG. 3 is a side view showing a state in which the bucket 12 is being excavated. When the vehicle is advanced in the direction of arrow A, the blade edge of the bucket 12 is thrust into the object Z and tilted back, a force is applied to the bucket 12 in the directions of arrows B and C. Therefore, a high hydraulic pressure is generated on the bottom side of the lift cylinder 13 and the tilt cylinder 15. Further, a force in the direction of arrow D is applied to the bucket 12 depending on the work posture, and in this case, a high hydraulic pressure is generated on the head side of the tilt cylinder 15. During this time, a large traveling driving force is generated on the front and rear wheels 4, 6. These hydraulic pressures and driving forces are obviously different during excavation work and non-excavation work. Therefore, by determining the respective reference values of the traveling driving force, the lift cylinder bottom pressure, and the tilt cylinder pressure, and confirming that at least one of the above three exceeds the reference value, it is possible to determine whether or not excavation work is being performed. You can make a reliable decision.

FIG. 4 is a system diagram showing a first embodiment of an example of the control device 40. In FIG. 4, a displacement control device 41 is connected to the variable displacement hydraulic pump 26. A tilt operation valve 43 connected to the tilt cylinder 15 and a lift operation valve 44 connected to the lift cylinder 13 are provided on the discharge circuit 42 of the variable displacement hydraulic pump 26. A bottom pressure detector 45 is provided on the bottom side of the lift cylinder 13, and hydraulic pressure detectors 46, 46 are provided on the bottom side and the head side of the tilt cylinder 15, respectively. The bottom pressure detector 45 and the oil pressure detector 46 are, for example, pressure switches. Capacity control device 41, bottom pressure detector 4
5, the hydraulic pressure detectors 46 and 46 are respectively the controller 5
Connected to 0. The driving force detection means 51 is a torque converter input shaft rotation speed detector 52, a torque converter output shaft rotation speed detector 53, and a speed stage detector for detecting the speed stage of the transmission 23 selected by the speed stage selection means 31. 54
It has and. A torque converter input shaft speed detector 52, a torque converter output shaft speed detector 53,
The speed stage detector 54 and the operating position detecting means 55 for detecting the operating position of the forward / backward operating means 30 are connected to the controller 50. The controller 50 inputs the torque converter input / output shaft speed and the speed stage of the transmission 23,
Calculation is performed using the performance curve of the torque converter and the reduction ratio of the speed reducer 25 to calculate the traveling driving force of the vehicle. Also,
The controller 50 is connected to the operation position detecting means 55 for detecting the operation position of the forward / backward moving operation means 30 and detects whether the transmission 23 is in the forward, neutral or reverse state.

Next, the control method will be described with reference to the flowchart of FIG. In step 101, the driver operates the forward / backward operating means 30 to instruct the transmission 23 to move forward. In step 102, the driver operates the speed stage selecting means 31 to select the speed stage of the transmission. In step 103, excavation work is started. Controller 104 in step 104
0 is input with the detection results from the driving force detecting means 51, the bottom pressure detector 45, and the hydraulic pressure detector 46 to calculate the traveling driving force,
At least one of the lift cylinder bottom pressure (for example, 250 kg / cm ² ) and the tilt cylinder pressure exceeds a predetermined value,
Moreover, it is determined whether or not a predetermined time (for example, 0.5 sec) has elapsed. If NO in step 104, step 10
Return to before 3. If YES in step 104, it is determined in step 105 that excavation work is in progress, and the process proceeds to step 106. In step 106, the controller 50 causes the variable displacement hydraulic pump 26 to have a predetermined capacity that is smaller than the maximum capacity (for example, a capacity that is 0.5 to 0.9 times the maximum capacity corresponding to the magnitude of the traveling driving force or hydraulic pressure). ) Is set. Step 107
Then, the controller 50 outputs a control signal to the displacement control device 41 to reduce the displacement of the variable displacement hydraulic pump 26 to the predetermined displacement. At the time when the excavation work is completed, the driver operates the forward-reverse traveling operation means 30 in step 108 to operate the transmission 2
Switch 3 to neutral or reverse. In step 109, the controller 50 inputs the detection signal from the operation position detection means 55 and determines whether the transmission 23 is in the neutral or reverse position. If NO in step 109, the process returns to step 107. If YES in step 109, it is determined in step 110 that the excavation work is completed, and the process proceeds to step 111. In step 111, the controller 50 stops the pump displacement control and returns the displacement of the variable displacement hydraulic pump 26 to the value before the control.

In step 104, the controller 50
Is calculated by inputting the detection results from the driving force detecting means 51, the bottom pressure detector 45, and the hydraulic pressure detector 46, and at least one of the traveling driving force, the lift cylinder bottom pressure, and the tilt cylinder pressure exceeds a predetermined value, Moreover, although it is determined whether or not the predetermined time has elapsed, the determination as to whether or not the predetermined time has elapsed may be omitted.

Since the control method and the control device for the variable displacement hydraulic pump of the working vehicle according to the present invention are configured and arranged as described above, the following effects can be obtained. When at least one of the driving force of the vehicle, the hydraulic pressure on the bottom of the lift cylinder, and the hydraulic pressure of the tilt cylinder exceeds a predetermined value, or at least one of the hydraulic pressures exceeds a predetermined value and a predetermined time elapses. At this time, it is determined that the work vehicle is under excavation work, and the capacity of the pump is reduced to a predetermined capacity smaller than the maximum capacity. Since the traveling drive force, the bottom side hydraulic pressure of the lift cylinder, and the hydraulic pressure of the tilt cylinder are obviously different between the excavation work and the non-excavation work, it can be reliably determined that the excavation work is being performed. Therefore, it is possible to effectively reduce the power loss, and there is no fear that the pump capacity is reduced and the work efficiency is reduced even during the non-excavation work. After the excavation work, when the operator sets the forward / backward operating means to the neutral or reverse position, the displacement control of the pump is stopped.
The time when the excavation work ends can be clearly determined. After the excavation work is completed, the operating speed of the work machine is increased, and there is no fear that workability will deteriorate.

In this embodiment, the work vehicle has been described as an articulated wheel loader, but other types of work vehicles may be used.

FIG. 6 is a system diagram of the control device 40a of the second embodiment. The same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only different portions will be described. Referring to FIG. 6, the controller 50 has a manual displacement control means 32 by which the driver can manually set the displacement of the variable displacement hydraulic pump 26, and whether or not the driver automatically controls the pump displacement. It is connected to the selectable capacity control selection means 33. Manual capacity control means 32,
The capacity control selection means 33 is, for example, a switch type or a dial type. Further, the controller 50 includes a steering refraction angle detector 56 and steering oil pressure detectors 57, 5 for detecting oil pressures of the left and right steering cylinders 9, 9, respectively.
It is connected to 7.

Next, the control method will be described. When the driver sets a desired hydraulic pump displacement by the manual displacement control means 32, the controller 50 inputs the signal,
The capacity control device 41 has priority over the capacity control described in the embodiment.
A control signal is output to control the variable displacement hydraulic pump 26 to the set displacement.

When the driver operates the capacity control selection means 33 and selects not to perform capacity control (for example, switch OFF), the controller 50 inputs the signal and outputs the capacity control signal of the first embodiment. Stop calling. When the driver operates the capacity control selection means 33 to select capacity control (for example, switch ON), the controller 5
0 transmits the capacity control signal described in the first embodiment.

The controller 50 is the steering refraction angle detector 5
6 and steering oil pressure detectors 57, 57, the detection results are input, and if either of them exceeds a predetermined value, the first
The transmission of the capacity control signal described in the embodiment is stopped.

As a result of the above control, the following effects are obtained. Since the manual displacement control means capable of controlling the pump displacement is provided, the operator can arbitrarily set the pump displacement depending on the soil quality and the like. For example, if the object is a lightweight object, the reduction amount of the pump capacity is reduced, and if it is a heavy object, the reduction amount is increased.
This can improve work efficiency. Since the capacity control selection means is provided, the driver can select whether or not to perform the capacity reduction control of the hydraulic pump during the excavation work according to the work status. Therefore, efficient work can be performed. FIG. 7 is a plan view showing a state in which the tooth tips of the bucket 12 are brought into contact with the object Z substantially parallel to the wheel loader 1 at the steering refraction angle θ. When the pump displacement reduction control is performed in such an attitude, most of the engine output is added to the vehicle driving side, and the driving force becomes large. As a result, the rear body 5 tends to move in the direction of the arrow with a large force, and an unreasonable force acts on each part of the vehicle, possibly shortening the life of the vehicle.
This tendency increases as θ increases. Figure 8 shows the object Z
On the other hand, the wheel loader 1 whose steering refraction angle is almost 0 is
It is a top view which shows the state contacting diagonally. In this case, when the wheel loader 1 is driven in the direction of arrow E, the bucket 12
A lateral force F acts on the wheel loader 1, and a moment M acts on the wheel loader 1. If the pump displacement reduction control is performed in this state, the driving force becomes large and an unreasonable force acts on each part of the vehicle, which may shorten the life of the vehicle. In the case of this figure, a difference occurs between the hydraulic pressures of the left and right steering cylinders 9, 9, and the larger the difference, the larger F becomes. According to the control method described above, the controller 50 stops the transmission of the capacity control signal when the steering refraction angle θ or the difference between the hydraulic pressures of the left and right steering cylinders 9, 9 exceeds a predetermined value. As a result, the power consumption of the hydraulic pump is increased, the driving force is reduced, the unreasonable force applied to each part of the vehicle is reduced, and the risk of shortening the vehicle life is reduced.

The control functions and control means of the present invention can be arbitrarily combined or changed or eliminated. In the first embodiment of the control device 40 shown in FIG. 4 and the second embodiment of the control device 40a shown in FIG. 6, the bottom pressure detector 45, the hydraulic pressure detectors 46 and 46, and the driving force detecting means 51 are respectively Although provided, any one of them may be provided, or each of them may be provided in combination. Further, in FIG. 6, the controller 50 is connected to a steering refraction angle detector 56 and steering oil pressure detectors 57 and 57 for detecting the oil pressures of the left and right steering cylinders 9 and 9, respectively. Detector 5
6, or only one of the steering oil pressure detectors 57, 57 may be connected.

[Brief description of drawings]

FIG. 1 is a side view of a wheel loader of an example of a work vehicle having a control device of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a side view of a working machine of the wheel loader of the present invention.

FIG. 4 is a system diagram of a control device according to the first embodiment of the present invention.

FIG. 5 is a flowchart for explaining a control method of the present invention.

FIG. 6 is a system diagram of a control device according to a second embodiment of the present invention.

FIG. 7: Articulate angle θ of the wheel loader
It is a top view which shows the work posture at the time of.

FIG. 8 is a plan view showing a state when the wheel loader excavates the ground from an oblique direction.

FIG. 9 is a side view showing an excavation position of a work machine of a conventional work vehicle.

[Explanation of symbols]

1 ... Wheel loader, 2 ... Driver's cab, 4 ... Rear wheel, 5 ... Rear vehicle body, 6 ... Front wheel, 7 ... Front frame, 8 ... Center pin,
9 ... Steering cylinder, 10 ... Working machine, 11 ... Lift arm, 12 ... Bucket, 13 ... Lift cylinder, 1
5 ... Tilt cylinder, 20 ... Power unit, 21 ... Engine, 22 ... Torque converter, 23 ... Transmission, 26 ... Variable displacement hydraulic pump, 30 ... Forward / backward operating means, 31 ... Speed stage selecting means, 32 ... Manual type Capacity control means, 33 ... Capacity control selection means, 40 ... Control device, 41 ... Capacity control device,
43 ... Tilt operating valve, 44 ... Lift operating valve, 45 ... Bottom pressure detector, 46 ... Hydraulic pressure detector, 50 ... Controller,
51 ... Driving force detecting means, 52 ... Torque converter input shaft rotation detector, 53 ... Torque converter output shaft rotation detector, 54 ... Speed stage detector, 55 ... Operating position detecting means, 5
6 ... Steering refraction angle detector, 57 ... Steering oil pressure detector.

Claims (10)

[Claims] 1. A method of controlling a hydraulic pump for a work machine of a work vehicle, wherein the work vehicle comprises a lift cylinder (13) and a tilt cylinder (15) for operating the work machine (10), and the lift cylinder (13). And a hydraulic pump that supplies a predetermined pressure oil to the tilt cylinder (15), and
And / or when the hydraulic pressure on the bottom side of the lift cylinder (13) and / or the hydraulic pressure on the tilt cylinder (15) exceeds a predetermined value, it is determined that excavation work is in progress, and then the hydraulic pump Is determined to be a predetermined capacity equal to or smaller than the maximum capacity, and then control for reducing the capacity of the hydraulic pump to a predetermined capacity is performed. 2. A method of controlling a hydraulic pump for a working machine of a working vehicle, wherein the working vehicle comprises a lift cylinder (13) and a tilt cylinder (15) for operating the working machine (10), and the lift cylinder (13). And a hydraulic pump that supplies a predetermined pressure oil to the tilt cylinder (15), and
And / or it is judged that excavation work is being performed when the hydraulic pressure on the bottom side of the lift cylinder (13) and / or the hydraulic pressure on the tilt cylinder (15) exceeds a predetermined value and a predetermined time has passed, Next, it is determined that the capacity of the hydraulic pump is reduced to a predetermined capacity equal to or less than the maximum capacity, and then control for reducing the capacity of the hydraulic pump to a predetermined capacity is performed. Control method. 3. The method for controlling a hydraulic pump for a working machine of a work vehicle according to claim 1 or 2, wherein the work vehicle includes a forward / backward operating means (30), and the forward / backward operating means (3).
(0) is determined to be the end of excavation work when it changes from forward to neutral or reverse operation position, and the control for reducing the capacity of the hydraulic pump to a predetermined capacity is stopped. For controlling hydraulic pumps for automobiles. 4. A control device for a hydraulic pump for a working machine of a working vehicle, wherein the working vehicle comprises a lift cylinder (13) and a tilt cylinder (15) for operating the working machine (10), and the lift cylinder (13). And a variable displacement hydraulic pump (26) for supplying a predetermined pressure oil to the tilt cylinder (15), and the control device (40) includes a driving force detecting means (51) for detecting the traveling driving force of the vehicle. A bottom pressure detector (45) for detecting the bottom side hydraulic pressure of the lift cylinder (13), a hydraulic pressure detector (46) for detecting the hydraulic pressure of the tilt cylinder (15), and the variable displacement hydraulic pump A capacity control device for controlling the capacity of (26) (4
1), the driving force detection means (51), and the bottom pressure detector (45)
, And the detected value from the oil pressure detector (46) is input and calculated,
When at least one of the values exceeds a predetermined value and a predetermined time has passed, the capacity control device (41) reduces the capacity of the variable displacement hydraulic pump (26) to a predetermined capacity equal to or less than a maximum capacity. Controller that outputs the capacity control signal
(50) A control device for a hydraulic pump for a working machine of a working vehicle, comprising: 5. A control device for a hydraulic pump for a working machine of a working vehicle, wherein the working vehicle comprises a lift cylinder (13) and a tilt cylinder (15) for operating the working machine (10), and the lift cylinder (13). And a variable displacement hydraulic pump (26) for supplying a predetermined pressure oil to the tilt cylinder (15), and the control device (40) is a bottom pressure detecting a bottom side oil pressure of the lift cylinder (13). A detector (45), a displacement control device (41) for controlling the displacement of the variable displacement hydraulic pump (26),
When the detected value from the bottom pressure detector (45) is input and calculated, and the detected value exceeds a predetermined value and a predetermined time has passed, the capacity control device (41) is provided with the variable capacitance type A controller (50) for outputting a capacity control signal for reducing the capacity of the hydraulic pump (26) to a predetermined capacity equal to or less than the maximum capacity, the control device for a hydraulic pump for a working machine of a work vehicle. 6. The control device for a hydraulic pump for a working machine of a work vehicle according to claim 4 or 5, wherein the work vehicle has a forward / backward operating means (30) and an operation of the forward / backward operating means (30). When the operation position detecting means (55) for detecting the position and the detection signal from the operation position detecting means (55) are input, and the operation position changes from forward to neutral or reverse position, the capacity control device (41 ), And a controller (50) for stopping transmission of a capacity control signal output to the control device for the hydraulic pump for the working machine of the working vehicle. 7. The control device for a hydraulic pump for a work machine of a work vehicle according to claim 4, 5 or 6, wherein the work vehicle has an articulated structure, and the control device (40) controls the operation of the vehicle. The steering refraction angle detector (56) for detecting the steering refraction angle, and the detection value of the steering refraction angle detector (56) are input, and when the steering refraction angle exceeds a predetermined angle, the capacitance control is performed. A controller for a working machine hydraulic pump of a work vehicle, comprising: a controller (50) for stopping transmission of a capacity control signal output to the device (41). 8. The control device for a hydraulic pump for a working machine of a working vehicle according to claim 4, 5, or 6, wherein the working vehicle has an articulated structure, and a pair of left and right steering cylinders for steering ( 9, 9), the control device (40), the left and right steering cylinders (9, 9)
Steering oil pressure detector that detects the oil pressure of each
(57, 57) and the detected value of the steering oil pressure detector (57, 57) are input, and the capacity output to the capacity control device (41) when the difference between the left and right hydraulic pressures exceeds a predetermined value. A controller (50) for stopping transmission of a control signal, the control device for a hydraulic pump for a working machine of a working vehicle. 9. The control device for a hydraulic pump for a working machine of a work vehicle according to claim 4, wherein the control device (40).
Is a control device for a hydraulic pump for a working machine of a working vehicle, comprising a manual displacement control means (32) capable of controlling the displacement of the variable displacement hydraulic pump (26). 10. The control device for a hydraulic pump for a working machine of a work vehicle according to claim 4, wherein the control device (40).
A control device for a hydraulic pump for a working machine of a work vehicle, comprising: a capacity control selecting means (33) capable of selecting whether or not to perform capacity control of the variable displacement hydraulic pump (26).