JP3853208B2 - Control method and control device of hydraulic pump for work machine of work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacity control method and a control apparatus for a hydraulic pump for a work machine of a work vehicle, particularly a civil work vehicle.
[0002]
[Prior art]
For example, in a hydraulic apparatus that drives a work machine of a wheel loader that is a civil engineering work vehicle, an oil pressure is required at the time of excavation work or the like, but the discharge amount may be small. In such a case, when a fixed displacement hydraulic pump is used, a large amount of pressure oil is returned to the tank, which causes a great power loss. In order to reduce this power loss, a method has been proposed in which the hydraulic pump is made to be a variable displacement type and the pump discharge amount is reduced during excavation work. As an example, U.S. Pat. S. There is one disclosed in Patent Number 6,073,442. According to this, at least one of the following conditions is satisfied: 1. The transmission is in the forward first speed stage position, 2. The working machine is in the excavation position, 3. The vehicle traveling speed is less than or equal to the set speed. When the condition is satisfied, it is determined that the work vehicle is in 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 work machine is defined as shown in FIG. FIG. 9 is a side view of the work machine 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 and contracted, the lift arm 72 swings around the arm pin 73. A bucket 75 is swingably attached to the tip 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 and contracted, the bucket 75 swings around the bucket pin 76. The excavation position of the work machine 70 is defined as the reference position of the line YY connecting the arm pin 73 and the bucket pin 76, and the case where the lift arm 72 is positioned below it is defined as the excavation position.
[0003]
[Problems to be solved by the invention]
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 necessarily performed, and there is 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 may be reduced, and work efficiency may be reduced. Further, depending on the soil quality, there are cases where the work is performed at the second forward speed, and at that time, the pump capacity is not reduced, so that power loss occurs.
Secondly, when the work machine 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.
Third, when the vehicle traveling speed is less than or equal to the set speed, the pump capacity is reduced to a predetermined capacity that is equal to or less than the maximum capacity. In some cases, it may move below the set speed. Even in such a case, the pump capacity is reduced, and the speed of the work implement may be reduced, resulting in a decrease in work efficiency. Fourth, when the transmission is at the first forward speed, the working machine is at the excavation position, and 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. During normal excavation, until just before the object, the bucket is slightly lifted from the ground in order to prevent the bucket from being grounded and running resistance is increased, and the bucket is immediately grounded immediately before being pushed into the object. In that case, there is a problem that the response speed of the work machine is slowed down, the operation is delayed, and the worker feels uncomfortable.
[0004]
The present invention has been made paying attention to the above-mentioned problems. After reliably detecting that the work vehicle is in an excavation work state, the pump capacity is reduced, the power loss is reduced, and the work efficiency is lowered. It is an object of the present invention to provide a control method and a control device for a hydraulic pump for a work machine of a work vehicle that does not give the operator a sense of incongruity.
[0005]
[Means, actions and effects for solving the problems]
In order to achieve the above object, according to a first aspect of the present invention, there is provided a method for controlling a hydraulic pump for a work machine of a work vehicle, wherein the work vehicle includes a lift cylinder and a tilt cylinder that operate the work machine, and the lift cylinder and the tilt cylinder. And a hydraulic pump that supplies a predetermined pressure oil to the vehicle. The When the hydraulic pressure on the bottom side of the ft cylinder exceeds a predetermined value, it is determined that excavation work is in progress, and control is performed to reduce the capacity of the hydraulic pump to a predetermined capacity equal to or less than the maximum capacity.
[0006]
According to the first invention, the driving force of the vehicle and The When the bottom side hydraulic pressure of the left cylinder exceeds a predetermined value, it is determined that the work vehicle is under excavation work, and 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 and the bottom side hydraulic pressure of the lift cylinder are clearly different between the excavation work and the non-excavation work, it can be determined that the excavation work is being performed, and effective power loss can be reduced. In addition, since the hydraulic pump capacity is not reduced during non-excavation work, there is no possibility of reducing work efficiency or feeling uncomfortable for the operator.
[0007]
According to a second aspect of the present invention, in the method for controlling a hydraulic pump for a work machine of a work vehicle, the work vehicle has a lift cylinder and a tilt cylinder that operate the work machine, and a hydraulic pressure that supplies predetermined pressure oil to the lift cylinder and the tilt cylinder. A pump, and driving driving force of the vehicle, and The A method for performing control to determine that excavation work is in progress when the oil pressure on the bottom side of the cylinder exceeds a predetermined value and a predetermined time has elapsed, and to reduce the capacity of the hydraulic pump to a predetermined capacity equal to or less than the maximum capacity It is said.
[0008]
According to the second invention, the driving force of the vehicle and The When the bottom side hydraulic pressure of the left cylinder exceeds a predetermined value and a predetermined time elapses, it is determined that the work vehicle is excavating and the hydraulic pump capacity is reduced to a predetermined capacity equal to or less than the maximum capacity. . The driving force and the bottom side hydraulic pressure of the lift cylinder are clearly different between excavation work and non-excavation work, and it is confirmed whether or not those values have passed over a predetermined time, so that the excavation work is surely It can be determined that there is an effective power loss reduction. In addition, since the hydraulic pump capacity is not reduced during non-excavation work, there is no possibility of reducing work efficiency or feeling uncomfortable for the operator.
[0009]
According to a third invention, in the first or second invention, the work vehicle includes a forward / reverse operation means, and the excavation work ends when the forward / backward operation means changes from forward to neutral or reverse operation position. This is a method of determining and stopping the control for reducing the capacity of the hydraulic pump to a predetermined capacity.
[0010]
According to the third aspect of the invention, when the operator changes the forward / backward operation means from the forward position to the neutral or reverse position, it is determined that the excavation work is finished, and the pump capacity reduction control is stopped. Therefore, the end of the excavation work is surely determined, and after the excavation work is completed, the operating speed of the work machine is increased, and the workability is not deteriorated.
[0011]
According to a fourth aspect of the present invention, in the control device for the hydraulic pump for a work machine of the work vehicle, the work vehicle has a lift cylinder and a tilt cylinder that operate the work machine, and a variable that supplies predetermined pressure oil to the lift cylinder and the tilt cylinder. A displacement type hydraulic pump, wherein the control device detects a driving force detecting means for detecting a driving force of the vehicle, a bottom pressure detector for detecting a bottom side oil pressure of the lift cylinder, and the variable displacement type hydraulic pump. A capacity control device for controlling the capacity of the motor, and input the detection values from the driving force detection means and the bottom pressure detector, and calculate, Both When the value exceeds a predetermined value, the displacement control device has a controller that outputs a displacement control signal for reducing the displacement of the variable displacement hydraulic pump to a predetermined displacement equal to or less than a maximum displacement.
[0012]
According to the fourth aspect of the present invention, the driving force of the vehicle, the hydraulic pressure on the bottom side of the lift cylinder both When the pressure exceeds a predetermined value and a predetermined time elapses, the capacity of the hydraulic pump can be reduced to a predetermined capacity. That is, it is possible to detect that the work vehicle is reliably excavating and reduce the pump capacity to a predetermined capacity, so that it is possible to effectively reduce power loss and obtain a work vehicle that can work efficiently.
[0013]
According to a fifth aspect of the present invention, in the control device for the hydraulic pump for a work machine of the work vehicle, the work vehicle has a lift cylinder and a tilt cylinder that operate the work machine, and a variable that supplies predetermined pressure oil to the lift cylinder and the tilt cylinder. A displacement type hydraulic pump, wherein the control device detects a driving force detecting means for detecting a driving force of the vehicle, a bottom pressure detector for detecting a bottom side oil pressure of the lift cylinder, and the variable displacement type hydraulic pump. A capacity control device for controlling the capacity of the motor, and input the detection values from the driving force detection means and the bottom pressure detector, and calculate, Both A controller that outputs a displacement control signal for reducing the displacement of the variable displacement hydraulic pump to a predetermined displacement equal to or less than a maximum displacement to the displacement control device when the detected value exceeds a predetermined value and a predetermined time has elapsed; It has composition which has.
[0014]
According to the fifth aspect of the invention, the driving force of the vehicle and the bottom hydraulic pressure of the lift cylinder Both sides When the pressure exceeds a predetermined value and a predetermined time elapses, the capacity of the hydraulic pump can be reduced to a predetermined capacity. That is, it is possible to detect that the work vehicle is reliably excavating and reduce the pump capacity to a predetermined capacity, so that it is possible to effectively reduce power loss and obtain a work vehicle that can work efficiently.
[0015]
A sixth invention is the fourth or fifth invention, wherein the work vehicle includes a forward / reverse operation means, an operation position detection means for detecting an operation position of the forward / reverse operation means, and a detection signal from the operation position detection means And a controller that stops transmission of the displacement control signal of the variable displacement hydraulic pump that is output to the displacement control device when the operation position changes from forward to neutral or reverse.
[0016]
According to the sixth invention, when the operation position of the forward / reverse operation means is in the neutral or reverse position, the transmission of the capacity control signal for reducing the capacity of the variable displacement hydraulic pump that is output to the capacity control device is stopped. Can do. Therefore, the end point of excavation work can be reliably detected, and the pump capacity is not reduced during non-excavation work. Therefore, there is no fear that work efficiency will be reduced.
[0017]
A seventh invention is the fourth, fifth or sixth invention, wherein the work vehicle has an articulated structure, and the control device includes a steering refraction angle detector for detecting a steering refraction angle of the vehicle, And a controller that inputs a detection value of the steering refraction angle detector and stops transmission of a capacity control signal to be output to the capacity control device when the steering refraction angle exceeds a predetermined angle.
[0018]
According to the seventh invention, when the articulate angle exceeds a predetermined angle, the displacement control of the hydraulic pump is stopped. As a result, the hydraulic pump consumes more of the engine output, The travel driving force of the vehicle is reduced, no excessive force is applied to each part of the vehicle, and there is no possibility of reducing durability.
[0019]
An eighth invention is the fourth, fifth or sixth invention, wherein the work vehicle has an articulated structure and includes a pair of left and right steering cylinders for steering, and the control device includes the left and right steering cylinders. The steering hydraulic pressure detector for detecting the hydraulic pressure of the oil and the detected value of the steering hydraulic pressure detector are input, and when the difference between the right and left hydraulic pressure exceeds a predetermined value, the capacity control is output to the capacity control device And a controller that stops signal transmission.
[0020]
According to the eighth aspect of the 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. As a result, the hydraulic pump consumes more of the engine output, The travel driving force of the vehicle is reduced, no excessive force is applied to each part of the vehicle, and there is no possibility of reducing durability.
[0021]
According to a ninth invention, in the fourth to eighth inventions, the control device includes a manual displacement control means capable of controlling a displacement of the variable displacement hydraulic pump.
[0022]
According to the ninth aspect, since the manual capacity control means capable of controlling the pump capacity is provided, for example, when the operator wants to arbitrarily set the pump capacity depending on the soil, it can be set to a desired capacity and work efficiency can be improved. it can.
[0023]
According to a tenth aspect of the present invention, in the fourth to ninth aspects of the present invention, the control device includes a displacement control selection means that can select whether or not to perform displacement control of the variable displacement hydraulic pump.
[0024]
According to the tenth aspect, since the capacity control selection means is provided, the driver can select whether or not to control the capacity of the hydraulic pump during excavation work according to the situation. Therefore, efficient work can be performed.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
A control method and a control device for a hydraulic pump for a work machine of a work vehicle according to the present invention
The embodiment will be described in detail with reference to the drawings.
[0026]
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, a front frame 7 having front wheels 6 and 6 is swingable to the left and right by a center pin 8 at a front portion of a rear vehicle body 5 having a cab 2, an engine room 3 and rear wheels 4 and 4. To form an articulated 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, 9, and the rear vehicle body 5 and the front frame 7 are center pins 8 by expanding and contracting the left and right steering cylinders 9, 9. As shown by the two-dot chain line, it is swung left and right and steered. The angle θ in the figure is called a steering refraction angle.
[0027]
1 and 2, a work machine 10 is attached to the front frame 7. That is, the bucket 12 is swingably attached to the distal end portion of the lift arm 11 whose base end portion is swingably attached to the front frame 7. The front frame 7 and the lift arm 11 are connected by a pair of lift cylinders 13 and 13, and the lift arm 11 swings by expanding and contracting the lift cylinders 13 and 13. A substantially central portion of the tilt arm 14 is swingably supported by the lift arm 11, and one end thereof 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.
[0028]
In FIG. 1, a power unit 20 is mounted on the rear vehicle body 5. The power unit 20 includes an engine 21, a torque converter 22, a forward / reverse switching, a transmission 23 capable of switching a plurality of shift stages, a distributor 24, speed reducers 25 and 25 for driving the rear wheels 4 and the front wheels 6, and the like. Has been. The engine 21 drives a variable displacement hydraulic pump 26 that supplies pressure oil to the lift cylinder 13 and the tilt cylinder 15.
[0029]
In the cab 2, the forward / reverse operation means 30, the speed stage selection means 31 of the transmission 23, the manual displacement control means 32 that can manually control the displacement of the variable displacement hydraulic pump 26, and automatically Capacity control selection means 33 capable of selecting whether or not to perform capacity control of the pump is provided. Each of the above means may be a lever type, a switch type, a dial type, or any other type.
[0030]
Next, excavation and loading work of the wheel loader 1 will be described. The driver operates the forward / reverse operation means 30 to advance the vehicle, and the speed stage selection means 31 selects the speed stage of the transmission 23 according to the object. The bucket 12 is positioned at the excavation position. Next, the blade edge of the bucket 12 is pushed into the object, the tilt cylinder is operated, the bucket 12 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 vehicle is moved backward by operating the forward / reverse operation means 30 while raising the bucket 12. Next, the vehicle advances and steers to approach the dump truck, dumps the bucket 12 at a predetermined position, and loads the object onto the dump truck bed.
[0031]
FIG. 3 is a side view showing a state where the bucket 12 is excavating. When the vehicle is advanced in the direction of the arrow A, the blade edge of the bucket 12 is pushed into the object Z and tilted back, 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, depending on the working posture, a force in the direction of arrow D is applied to the bucket 12, and in this case, a high hydraulic pressure is generated on the head side of the tilt cylinder 15. During this time, a large driving force is generated on the front and rear wheels 4 and 6. These oil pressure and driving force are clearly different between excavation work and non-digging work. Therefore, it is determined whether or not excavation work is in progress by determining respective reference values for the driving force, lift cylinder bottom pressure, and tilt cylinder pressure, and confirming that at least one of the above three values exceeds the reference value. Judgment can be made with certainty.
[0032]
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 interposed 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 and 46 are provided on the bottom side and the head side of the tilt cylinder 15, respectively. The bottom pressure detector 45 and the hydraulic pressure detector 46 are pressure switches, for example. The capacity control device 41, the bottom pressure detector 45, and the oil pressure detectors 46 and 46 are connected to the controller 50, respectively. The driving force detection means 51 includes a torque converter input shaft rotational speed detector 52, a torque converter output shaft rotational speed detector 53, and a speed stage detector that detects the speed stage of the transmission 23 selected by the speed stage selection means 31. 54. The torque converter input shaft rotational speed detector 52, the torque converter output shaft rotational speed detector 53, the speed stage detector 54, and the operation position detecting means 55 for detecting the operation position of the forward / reverse operation means 30 are provided to the controller 50. Connected. The controller 50 inputs the torque converter input, the output shaft speed, and the speed stage of the transmission 23, calculates using the performance curve of the torque converter and the reduction ratio of the speed reducer 25, and calculates the driving force of the vehicle. . Further, the controller 50 is connected to an operation position detection means 55 for detecting the operation position of the forward / reverse operation means 30 and detects whether the transmission 23 is in a forward, neutral or reverse state.
[0033]
Next, a control method will be described based on the flowchart of FIG.
In step 101, the driver operates the forward / reverse operation means 30 to instruct the transmission 23 to move forward.
In step 102, the driver operates the speed stage selection means 31 to select the speed stage of the transmission.
In step 103, excavation work is started.
In step 104, the controller 50 inputs and calculates the detection results from the driving force detection means 51, the bottom pressure detector 45, and the hydraulic pressure detector 46 to calculate the travel driving force and the lift cylinder bottom pressure (for example, 250 kg / cm). ² ), It is determined whether at least one of the tilt cylinder pressures exceeds a predetermined value and a predetermined time (for example, 0.5 sec) has elapsed. If NO at step 104, the process returns to before step 103.
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 determines a predetermined capacity that is smaller than the maximum capacity of the variable displacement hydraulic pump 26 (for example, a capacity that is 0.5 to 0.9 times the maximum capacity corresponding to the magnitude of the driving force or hydraulic pressure). ) Is set.
In step 107, the controller 50 outputs a control signal to the displacement control device 41, and reduces the displacement of the variable displacement hydraulic pump 26 to the predetermined displacement.
When the excavation work is completed, the driver operates the forward / reverse operation means 30 in step 108 to switch the transmission 23 to neutral or reverse.
In step 109, the controller 50 inputs a detection signal from the operation position detecting means 55, and determines whether or not the transmission 23 is in the neutral or reverse position.
If NO at step 109, the process returns to before step 107.
If YES in step 109, it is determined in step 110 that the excavation work has ended, 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 that before the control.
[0034]
In step 104, the controller 50 inputs and calculates 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 is calculated. However, the determination of whether or not a predetermined time has elapsed may be omitted.
[0035]
Since the control method and the control device for the variable displacement hydraulic pump for a work vehicle according to the present invention have the above-described method and configuration, the following effects can be obtained.
When at least one of the vehicle driving force, the lift side hydraulic pressure 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 has elapsed. 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 less than the maximum capacity. Since the traveling driving force, the lift side hydraulic pressure of the lift cylinder, and the hydraulic pressure of the tilt cylinder are clearly different between the excavation operation and the non-excavation operation, it can be reliably determined that the excavation operation is being performed. Therefore, the power loss can be effectively reduced, and the pump capacity can be reduced despite the non-excavation work, and the work efficiency is not lowered.
After the excavation work is completed, the displacement control of the pump is stopped when the operator sets the forward / reverse operation means to the neutral or reverse position, so the end point of the excavation work 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 is reduced.
[0036]
In the present embodiment, the work vehicle has been described as an articulated wheel loader, but other types of work vehicles may be used.
[0037]
FIG. 6 is a system diagram of the control device 40a of the second embodiment. The same members as those of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different portions will be described. In FIG. 6, the controller 50 includes a manual displacement control means 32 that allows the driver to manually set the displacement of the variable displacement hydraulic pump 26, and whether or not the driver automatically performs the pump displacement control. It is connected to a capacity control selection means 33 that can be selected. The manual capacity control means 32 and the capacity control selection means 33 are, for example, a switch type or a dial type. The controller 50 is connected to a steering refraction angle detector 56 and steering hydraulic pressure detectors 57 and 57 that detect hydraulic pressures of the left and right steering cylinders 9 and 9, respectively.
[0038]
Next, a 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 and outputs a control signal to the displacement control device 41 in preference to the displacement control described in the first embodiment. Then, the variable displacement hydraulic pump 26 is controlled to a set capacity.
[0039]
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 stops the transmission of the capacity control signal described in the first embodiment. To do. When the driver selects the capacity control by selecting the capacity control selection means 33 (for example, switch ON), the controller 50 transmits the capacity control signal described in the first embodiment.
[0040]
The controller 50 inputs detection results from the steering refraction angle detector 56 and the steering hydraulic pressure detectors 57 and 57, and when any of the detection values exceeds a predetermined value, the capacity control signal described in the first embodiment is transmitted. Stop.
[0041]
As a result of the above control, the following effects are obtained. Since the manual capacity control means capable of controlling the pump capacity is provided, the operator can arbitrarily set the pump capacity depending on the soil. For example, if the object is a light object, the reduction amount of the pump capacity is reduced, and if the object is a heavy object, the reduction amount is increased. Thereby, working efficiency can be improved. Since the capacity control selection means is provided, the driver can select whether or not to perform capacity reduction control of the hydraulic pump during excavation work according to the work situation. Therefore, efficient work can be performed. FIG. 7 is a plan view showing a state in which the wheel loader 1 is brought into contact with the object Z substantially in parallel with the object Z in the state of the steering refraction angle θ. When the pump displacement reduction control is performed in such a posture, much of the engine output is applied to the vehicle driving side, and the driving force increases. As a result, the rear vehicle body 5 tends to advance with a large force in the direction of the arrow, and an excessive force acts on each part of the vehicle, which may shorten the vehicle life. This tendency increases as θ increases. FIG. 8 is a plan view showing a state in which the wheel loader 1 having a steering refraction angle of approximately 0 is in contact with the object Z obliquely. In this case, when the wheel loader 1 is driven in the direction of arrow E, a lateral force F acts on the bucket 12 and a moment M acts on the wheel loader 1. If the pump capacity reduction control is performed in this state, the driving force increases and an excessive force acts on each part of the vehicle, which may shorten the vehicle life. In the case of this figure, a difference arises in the oil pressure of the left and right steering cylinders 9, 9, and F becomes larger as the difference is larger. According to the above control method, the controller 50 stops the transmission of the capacity control signal when the steering refraction angle θ or the difference in hydraulic pressure between the left and right steering cylinders 9 and 9 exceeds a predetermined value. This Because the hydraulic pump consumes more of the engine output, The driving force is reduced, the unreasonable force applied to each part of the vehicle is reduced, and the possibility of shortening the vehicle life is reduced.
[0042]
The control function and control means of the present invention can be arbitrarily changed or abolished. 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 detection means 51 are respectively provided. However, any one of them may be provided or a combination of them may be provided. In FIG. 6, the controller 50 is connected to the steering refraction angle detector 56 and the steering hydraulic pressure detectors 57 and 57 for detecting the hydraulic pressures of the left and right steering cylinders 9 and 9, respectively. Only one of the detector 56 and the steering oil pressure detectors 57 and 57 may be connected.
[Brief description of the drawings]
FIG. 1 is a side view of a wheel loader as 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 is a plan view showing a working posture of the wheel loader at an articulate angle θ.
FIG. 8 is a plan view showing a state when the wheel loader excavates natural 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]
DESCRIPTION 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 DESCRIPTION OF SYMBOLS ... Bucket, 13 ... Lift cylinder, 15 ... Tilt cylinder, 20 ... Power unit, 21 ... Engine, 22 ... Torque converter, 23 ... Transmission, 26 ... Variable displacement hydraulic pump, 30 ... Forward / reverse operation means, 31 ... Speed Stage selection means 32 ... Manual capacity control means 33 ... Capacity control selection means 40 ... Control device 41 ... Capacity control device 43 ... Tilt operation valve 44 ... Lift operation valve 45 ... Bottom pressure detector 46 DESCRIPTION OF SYMBOLS ... Hydraulic pressure detector, 50 ... Controller, 51 ... Driving force detection means, 52 ... Torque converter input shaft rotation detector, 53 ... Torque converter output shaft rotation detector, 54 ... Speed stage detection , 55 ... operating position detecting means, 56 ... steering angle of refraction detector, 57 ... steering hydraulic detector.

Claims (10)

In a control method of a hydraulic pump for a work machine of a work vehicle,
The work vehicle includes a lift cylinder (13) and a tilt cylinder (15) that operate a work machine (10), and a hydraulic pump that supplies predetermined pressure oil to the lift cylinder (13) and the tilt cylinder (15). Prepared,
It determines that the driving force of the vehicle, Oyo oil pressure of the bottom side of the beauty Li Futoshirinda (13) are under excavation operation when exceeding a predetermined value,
A control method for a hydraulic pump for a work machine of a work vehicle, wherein control is performed to reduce the capacity of the hydraulic pump to a predetermined capacity equal to or less than a maximum capacity. In a control method of a hydraulic pump for a work machine of a work vehicle,
The work vehicle includes a lift cylinder (13) and a tilt cylinder (15) that operate a work machine (10), and a hydraulic pump that supplies predetermined pressure oil to the lift cylinder (13) and the tilt cylinder (15). Prepared,
Driving force of the vehicle, Oyo oil pressure of the bottom side of the beauty Li Futoshirinda (13) exceeds a predetermined value,
And when a predetermined time has passed, it is judged that excavation work is in progress,
A control method for a hydraulic pump for a work machine of a work vehicle, wherein control is performed to reduce the capacity of the hydraulic pump to a predetermined capacity equal to or less than a maximum capacity. In the control method of the hydraulic pump for working machines of a work vehicle according to claim 1 or 2,
The work vehicle includes a forward / reverse operation means (30),
When the forward / reverse operation means (30) changes from forward to neutral or reverse operation position, it is determined that the excavation work is finished,
A control method for a hydraulic pump for a work machine of a work vehicle, wherein control for reducing the capacity of the hydraulic pump to a predetermined capacity is stopped. In a control device for a hydraulic pump for a work machine of a work vehicle,
The work vehicle includes a lift cylinder (13) and a tilt cylinder (15) that operate a work machine (10), and a variable displacement hydraulic pressure that supplies predetermined pressure oil to the lift cylinder (13) and the tilt cylinder (15). A pump (26),
The control device (40) includes a driving force detection means (51) for detecting the driving force of the vehicle,
A bottom pressure detector (45) for detecting the bottom oil pressure of the lift cylinder (13);
A displacement control device (41) for controlling the displacement of the variable displacement hydraulic pump (26);
When the detection values from the driving force detection means (51) and the bottom pressure detector (45) are inputted and calculated, and both values exceed a predetermined value,
The capacity control device (41) has a controller (50) for outputting a capacity control signal for reducing the capacity of the variable capacity hydraulic pump (26) to a predetermined capacity equal to or less than a maximum capacity. Hydraulic pump control device for work machines. In a control device for a hydraulic pump for a work machine of a work vehicle,
The work vehicle includes a lift cylinder (13) and a tilt cylinder (15) that operate a work machine (10), and a variable displacement hydraulic pressure that supplies predetermined pressure oil to the lift cylinder (13) and the tilt cylinder (15). A pump (26),
The control device (40)
Driving force detection means (51) for detecting the driving force of the vehicle;
A bottom pressure detector (45) for detecting the bottom oil pressure of the lift cylinder (13);
A displacement control device (41) for controlling the displacement of the variable displacement hydraulic pump (26);
The detection values from the driving force detection means (51) and the bottom pressure detector (45) are inputted and calculated, both detection values exceed a predetermined value,
And when the predetermined time has passed,
The capacity control device (41) has a controller (50) for outputting a capacity control signal for reducing the capacity of the variable capacity hydraulic pump (26) to a predetermined capacity equal to or less than a maximum capacity. Hydraulic pump control device for work machines. In the control apparatus of the working machine hydraulic pump for a work vehicle according to claim 4 or 5,
The work vehicle is
Forward / reverse operation means (30),
An operation position detecting means (55) for detecting an operation position of the forward / reverse operation means (30);
A controller that inputs a detection signal from the operation position detection means (55) and stops transmission of a capacity control signal to be output to the capacity control device (41) when the operation position changes from forward to neutral or reverse position (50) and a hydraulic pump control device for a work machine of a work vehicle. In the control apparatus of the hydraulic pump for working machines of a work vehicle of Claim 4 or 5 or 6,
The work vehicle has an articulated structure,
The control device (40) includes a steering refraction angle detector (56) for detecting a steering refraction angle of the vehicle,
A controller that inputs a detection value of the steering refraction angle detector (56) and stops transmission of a capacity control signal to be output to the capacity control device (41) when the steering refraction angle exceeds a predetermined angle ( And 50) a hydraulic pump control device for a work machine of a work vehicle. In the control apparatus of the hydraulic pump for working machines of a work vehicle of Claim 4 or 5 or 6,
The work vehicle has an articulated structure and includes a pair of left and right steering cylinders (9, 9) for steering,
The control device (40) includes a steering hydraulic pressure detector (57, 57) for detecting the hydraulic pressure of the left and right steering cylinders (9, 9), respectively.
The detection value of the steering oil pressure detector (57, 57) is input, and when the difference between the left and right hydraulic pressure exceeds a predetermined value, transmission of the capacity control signal to be output to the capacity control device (41) is stopped. A control device for a hydraulic pump for a work machine of a work vehicle, comprising a controller (50). In the control apparatus of the working machine hydraulic pump for work vehicles according to claim 4-8,
The control device (40) includes a manual displacement control means (32) capable of controlling the displacement of the variable displacement hydraulic pump (26), and the control device for the working machine hydraulic pump of the work vehicle. In the control apparatus of the working machine hydraulic pump for work vehicles according to claim 4-9,
The control device (40) has a displacement control selection means (33) capable of selecting whether or not to perform displacement control of the variable displacement hydraulic pump (26). Hydraulic pump control device.

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