JPH09184501A - Lift control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform lifting control of a work device quickly and without causing overshoot. A hydraulic cylinder (2) for driving and lowering a plow connected to a traveling vehicle body, a control valve (14) for controlling the hydraulic cylinder (2), and a lever (9) for setting the height of the plow against the vehicle body are provided. A lift arm sensor 11 for measuring the height with respect to the vehicle body is provided, an electric control device 13 is provided, and a deviation between the control target set by the lever 9 and the height of the plow measured by the lift arm sensor 11 is provided. The speed setting means A is provided to set the target ascending / descending speed of the plow higher as is larger, and to set the acceleration during the ascending / descending operation higher as the deviation is larger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a hydraulic actuator for driving and raising a working device which is connected to the rear end of a traveling vehicle body so as to be movable up and down, and a control valve for controlling this hydraulic actuator is based on the operation of an operating tool. The present invention relates to an improvement of a lifting control device that operates to lift a working device.

[0002]

2. Description of the Related Art Conventionally, there is an elevator control device configured as described above as disclosed in Japanese Patent Laid-Open No. 3-56702. In this conventional example, the height of the current work device and the current height of the work device are controlled when the work device is raised and lowered. The larger the deviation from the target height,
The target opening of the control valve that controls the hydraulic oil to the hydraulic actuator is set to a large value, and when starting the lifting of the working device, gradually increase the opening until the control valve reaches the target opening and start the lifting. The control operation is set so as to smoothly perform and when the working device approaches the target height, the opening degree of the control valve is reduced to reduce the ascending / descending speed and smoothly stop.

[0003]

In the above-mentioned conventional example, as the difference (deviation) between the current height of the working device and the target height is larger, the working device is moved up and down at a higher speed, so that quick raising and lowering is possible. It has a good aspect that it is difficult to generate a shock because the speed is decelerated at the time of starting the ascending / descending and at the time of stopping the ascending / descending. However, in the configuration of the conventional example, the opening degree is increased at the start of lifting and lowering of the working apparatus regardless of the control target (the conventional example does not describe how the expansion rate of the opening degree is set). Considering the case of performing the raising / lowering control in the form of raising / lowering greatly and the case of performing the raising / lowering control in the form of raising / lowering the work device slightly, for example, the opening of the control valve is controlled at a fixed expansion rate. If the degree of expansion is set low, there is no problem in raising and lowering the working device if the deviation is small, but if the deviation is large, it takes time for the working device to reach the desired lifting speed. In the case where the work efficiency is lowered, and conversely, the degree of expansion of the opening is set high, when the deviation is large, the time until the working device reaches the desired lifting speed can be shortened, but the deviation When there are few There is room for improvement may be overshooting the apparatus.

An object of the present invention is to reasonably provide a lifting control device which can smoothly raise and lower a working device without lowering work efficiency when the deviation of control is large, and without causing overshoot when the deviation is small. There is a point in configuring.

[0005]

As described at the beginning, the first feature of the present invention is to provide a hydraulic actuator for driving and raising a working device which is connected to the rear end of the traveling machine body so as to be able to move up and down. In a lifting control device that raises and lowers a working device by operating a control valve for controlling the working device based on the operation of the operating device, the working device increases as the deviation between the control target set by the operating tool and the height of the working device increases. In addition to setting the target ascending / descending speed to be high, a speed setting means for setting a high speed increase rate during the ascending / descending operation is provided, and its operation is as follows.

A second feature of the present invention is that, after starting the ascending / descending of the working device, when the deviation decreases to a value set based on the deviation at the start of the ascending / descending, the speed increase is stopped and the ascending / descending operation is performed. It is characterized in that it is provided with deceleration means for reducing the ascending / descending speed at a speed decrease rate that is a value proportional to the speed increase rate set at that time, and its operation is as follows.

A third feature of the present invention is that the hydraulic actuator is composed of a hydraulic cylinder, the control valve is of an electromagnetic operation type, and the control operation of the setting means is based on the deviation. The maximum opening is set, and the control current value for the control valve is set so as to set the increase rate of the opening until reaching the maximum opening based on the deviation. On the street.

[Operation] According to the first feature, the larger the deviation between the control target set by the operating tool and the height of the working device, the higher the speed setting means sets the target lifting speed of the working device, and at the same time, Since the speed increase rate during lifting operation is set to a high value, when the work device is moved up and down significantly, the work device is accelerated at a relatively high acceleration, and as a result, the work efficiency is increased to the desired lifting speed. Is difficult to reduce,
When the work device is slightly moved up and down, the work device is not overshot because the speed is increased at a relatively low acceleration and the speed is increased to a relatively low speed.

According to the second feature, when the work device starts to move up and down, and the deviation reduces to a value set on the basis of the deviation at the start of the up and down, the deceleration means is proportional to the speed increase rate. Since the ascending / descending speed of the work device is reduced by the speed reduction rate of the value, the elevator operation can be reasonably decelerated and the elevator operation can be stopped without causing overshoot or shock regardless of the deviation at the start of the elevator.

According to the third feature, the speed setting means electrically operates the electromagnetically operated control valve, so that the speed setting means is structured to be mechanically operated to operate the control valve. Is simple and the number of actuating members can be reduced, so that highly accurate control is possible.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows the rear body 1 of an agricultural tractor.
The side of the vehicle body 1 is provided with a pair of left and right lift arms 3 which can be driven up and down by the operation of a hydraulic cylinder 2 as a hydraulic actuator, and a rear end of the vehicle body 1 is vertically moved. A plow 6 as a working device is connected via a three-point link mechanism composed of a single swingable top link 4 and a pair of left and right lower links 5 swingable up and down, and the lower link 5 and the lift are linked. By connecting the arm 3 and the arm 3 in a suspended state by the lift rod 7, the plow 6 can be moved up and down by the operation of the hydraulic cylinder 2.

A driver's seat 8 on which an operator is seated is provided at the rear of the vehicle body 1, and a position lever 9 as an operating tool for determining the height of the plow 6 with respect to the vehicle body is provided on the right side of the driver's seat 8. A potentiometer-type setting device 10 for measuring the operating position of the lever 9 is provided at the base end of the position lever 9. At the base end of the lift arm 3, a potentiometer-type lift arm sensor 1 for measuring the height of the plow 6 with respect to the vehicle body from the swinging posture of the lift arm 3.
1, and a traction load sensor 12 composed of a differential transformer, a strain gauge or the like for measuring the traction load of the plow 6 at the time of plowing work at the base ends of the left and right lower links 5. .

As shown in FIG. 2, a system for inputting signals from the setting device 10, the lift arm sensor 11, and the traction load sensor 12 to a control device 13 having a microprocessor is formed, and at the same time, a hydraulic pressure is set. Solenoid valve 1 as a control valve for controlling the amount of hydraulic oil supplied to and discharged from the cylinder 2.
An output system for 4 is formed. Further, the solenoid valve 14 is configured so as to increase the opening degree as the current value supplied to the solenoid solenoid increases to increase the supply / discharge amount of hydraulic oil. In this control device 13, position control for raising and lowering the plow 6 to a height based on the vehicle body 1 is performed.
As shown in FIG. 4, when the plowing 6 is tilled in the field, the pulling load acting on the plow 6 is measured by the pulling load sensor 12, and the plow 6 can be raised and lowered so as to maintain the measurement result at the set value. The position control operation will be described below.

In this position control, as shown in FIG. 3, the signal from the setting device 10 and the signal from the lift arm sensor 11 are input, and the signals PS and P from each are input.
An operation of inputting a control operation for obtaining the deviation ΔP from R at a set cycle in the control device 13 is set (# 101 to # 1).
(Step 03), the following control is performed based on the deviation ΔP thus obtained. That is, as shown in FIG. 4, when the absolute value of the deviation ΔP is larger than the preset dead zone M value, the ascending / descending direction is determined, and the maximum flow rate QMAX and the flow rate increase rate ΔQ are determined based on the deviation ΔP. And the deceleration start point D (steps # 201 to # 203).

The dead zone M is a signal area having a constant width, and even if the value of the deviation ΔP fluctuates within the dead zone M, the elevating control is not performed. Even if it vibrates up and down, it is set to avoid up / down control. Incidentally, the speed setting means A of claim 1 is constituted by step # 203 of this control operation.

Next, the maximum flow rate QMAX and the flow rate increase rate Δ
Q is a simple calculation based on the deviation ΔP so that a larger value is set as the deviation ΔP is larger, or is set by reading preset data,
Further, the maximum flow rate QMAX does not exceed the value when the opening degree of the solenoid valve 14 is set to the maximum. At the deceleration start point D, the amount of hydraulic oil supplied by the solenoid valve 14 is the maximum flow rate QMA.
After reaching X, when the solenoid valve 14 is closed at a decrease rate (negative ΔQ value) whose absolute value is equal to the flow rate increase rate ΔQ, when the solenoid valve 14 is closed, the deviation ΔP is 0, or , Is set based on the value of the lift arm sensor 3 at the start of lifting and lowering so as to be included in the dead zone M.

Next, when the maximum flow rate QMAX, the flow rate increase rate ΔQ, and the deceleration start point D are set, the solenoid valve 14 is controlled to start the elevating and lowering of the plow 6, and the flow rate increase rate ΔQ is obtained. The current supplied to the electromagnetic solenoid of the valve 14 is P
It is increased by means such as WM modulation and reaches the maximum flow rate QMAX at the same time, or after the maximum flow rate QMAX is reached,
Based on the signal from the lift arm sensor 11, the plow 6
When it is determined that the height of the vehicle with respect to the vehicle has reached the deceleration start point D (steps # 204, # 205), a decrease rate (a value of negative ΔQ) whose absolute value is equal to the flow rate increase rate ΔQ is set, The current supplied to the electromagnetic solenoid is operated in a closing direction by means of PWM modulation or the like so as to obtain this reduction rate, and as a result of this operation, the deviation ΔP exists within the preset dead zone M. When the condition is reached,
The solenoid valve 14 is completely closed to stop the lifting control (steps # 206 to # 209). still,
Step # 206 constitutes the deceleration means B of claim 2.

As an example of three kinds of control operations as described above, as shown in FIG. 5, set values of different sizes based on the current height PR of the plow 6 (not shown in the drawing) ( Target value) PS (shown in the figure at a position overlapping the time axis)
When is set, each deviation ΔP (not shown in the figure)
The maximum flow rate QMAX is set at the same time as the maximum flow rate QMAX is set, and if the maximum flow rate QMAX does not reach the maximum flow rate of the control valve, 1/2 of the operating stroke is set. When the maximum flow rate QMAX reaches the maximum flow rate of the control valve 14, the deceleration start point D is reached, and the deceleration start point D is reached while the maximum flow rate is being supplied. When it reaches, the amount of oil is reduced at a negative flow rate increase rate ΔQ, that is, the flow rate decrease rate whose absolute value is equal to the flow rate increase rate ΔQ, and the height of the plow is set to the set value (target value) PS by this operation. When it reaches, the deviation ΔP inevitably reaches “0”, and at this timing, the supply and discharge of the hydraulic oil is stopped to stop the elevation.

In this control system, when the position lever 9 is operated in the lowering direction to set the plow 6 to a height at which the plow 6 comes into contact with the field and can be cultivated, the signal from the traction load sensor 12 is fed back to the automatic control. The control operation is set so that the traction load control is started automatically. In this control, the control target value of the traction load control is set to a larger load value as the position lever is operated in the lowering direction. The control operation is set so that the depth of rise is also deep (the control operation is not described in detail).

As described above, in the present invention, when the plow 6 is moved up and down in the position control mode, the greater the difference between the control target set by the position lever 9 and the current height of the plow 6, that is, the deviation ΔP. The larger the value, the higher the target ascending / descending speed, and the larger the speed increase rate (acceleration) until reaching this ascending / descending speed, so that quick ascending / descending is possible and, at the same time, plowing work with the plow 6, for example. When starting, the position lever 9 is greatly lowered to increase the plunge speed of the plow 6 into the field to obtain a desired working depth in a short time. In this case, smooth operation at high speed and high acceleration raises and lowers to the target height in a short time, and when performing a slight elevation such as inching, it moves at low speed and low acceleration. The occurrence of over door has also become a thing to be suppressed.

[Other Embodiments] The present invention can be applied to, for example, position control of a rotary tiller other than the above embodiments.

[0022]

Therefore, when the control deviation is large, the working efficiency is not lowered, and when the deviation is small, the lifting control device capable of smoothly lifting the working device without causing overshoot is rationally constructed. (Claim 1). Further, even when the ascent / descent is stopped, it is possible to smoothly stop in a state in which it is more difficult to generate an overshoot by reasonably decelerating (Claim 2), and it is possible to perform a desired operation simply and accurately by electric control (Claim 2). Item 3).

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a side view of a rear part of an agricultural tractor.

FIG. 2 is a block circuit diagram of a control system.

FIG. 3 is a flowchart of a deviation acquisition routine.

FIG. 4 is a flowchart of a position control routine.

FIG. 5 is a graph showing changes in the supply amount of hydraulic oil during position control.

[Explanation of symbols]

 1 Traveling Vehicle 2 Hydraulic Actuator 9 Operation Tool 14 Control Valve A Speed Setting Means B Speed Reduction Means

Claims (3)

[Claims] 1. A control valve (14) for controlling said hydraulic actuator (2), comprising a hydraulic actuator (2) for driving and lifting a working device (6) which is connected to the rear end of a traveling vehicle body (1) so as to be able to move up and down. ) Is operated based on the operation of the operating tool (9) to raise and lower the working device (6), and the control target of the operating tool (9) and the working device (6) are set. The greater the deviation from the height, the working device (6)
1. A lifting control device comprising speed setting means (A) for setting a high target lifting speed and a high speed increase rate during lifting operation. 2. The speed increase is stopped when the deviation of the working device (6) is reduced to a value set based on the deviation at the start of the ascending / descending after the ascending / descending of the working device (6) is started,
2. The lifting control device according to claim 1, further comprising a deceleration means (B) for reducing the lifting speed at a speed decreasing rate that is a value proportional to the speed increasing rate set during the lifting. 3. The hydraulic actuator (2) is composed of a hydraulic cylinder, the control valve (14) is of an electromagnetic operation type, and the control operation of the speed setting means (A) is
A control current value for the control valve (14) is set so as to set the maximum opening degree of the control valve (14) based on the deviation and to set an increase rate of the opening degree until the maximum opening degree is reached based on the deviation. The elevation control device according to claim 1, wherein: