JP2003061406A - Lifting and lowering apparatus of traveling vehicle for working - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lifting and lowering apparatus for traveling vehicles for working in which smooth horizontal control scarcely causing shock can be kept even when a field state is diversely different by carrying out positive changeover of sensitivity without changing a dead zone. SOLUTION: When a mode exchange switch is changed over from an ordinary control mode to an adjustment mode, a control electric current value obtained when a lift rod cylinder 12 starts extension from the shortest position is stored by a horizontal control means and when the mode exchange switch is changed over from the adjustment mode to a sensitivity changeover mode, a plurality of output ratio characteristics determined by the difference between an output ratio changing from a minimum value of control electric current fed to a lift rod value 13 to a maximum value thereof and the change of expansion and contraction length of the lift rod cylinder 12 detected by the detection means are stored in the horizontal control means and a sensitivity of horizontal control is changed over by changeover of the each output ratio characteristic.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a lifting control device for lifting and lowering a working machine supported by a working vehicle such as an agricultural tractor. 2. Description of the Related Art Conventionally, a working machine which is supported on a lift arm of a tractor so as to be able to move up and down is held horizontally by an extension and contraction operation of a lift rod cylinder with respect to a machine body which inclines in a traveling left and right direction during traveling. A lift control device configured is known. In the lift control device, expansion and contraction control of the lift rod cylinder is performed by changing a control current value of an electromagnetic proportional control valve that configures a lift rod valve. In the electromagnetic proportional control valve, the control current range of the control current value for starting the extension from the most retracted position with respect to the lift rod cylinder and the control current value for stopping the extension at the most extended position is constant, and the control current range is determined based on the change of the control current. Control the expansion and contraction of the lift rod cylinder. It is necessary to change the sensitivity of the horizontal control in a field state that is changing to the conventional state. Conventionally, in the detecting means for detecting the inclination of the body in the left-right direction, the dead zone can be set to be large or small with respect to the change width of the inclination. Was compatible. [0003] The present invention was created in the course of research and development aimed at improving the accuracy of the above-described horizontal control. It is an object of the present invention to provide a lifting and lowering control device of a working vehicle that can maintain smooth horizontal control with less shock even when field conditions are variously varied by actively changing the sensitivity. [0004] In order to solve the problems, the technical means employed by the present invention are a detecting means for sequentially detecting the expansion and contraction length of a lift rod cylinder, and a working machine supported by the lift rod cylinder. Horizontal position of the lift rod is calculated by calculating a correction value for the horizontal position by detecting a change in the horizontal position of the horizontal position, and the expansion / contraction drive of the lift rod valve is controlled in accordance with a difference from the detection value of the lift rod based on the correction value for the horizontal position. With the control means, when switching from the normal control mode to the adjustment mode, the control current value when the lift rod starts extending from the most retracted position is stored in the horizontal control means,
And, when the mode is switched to the sensitivity switching mode, it is determined by the output ratio of the control current supplied to the lift rod valve from the minimum value to the maximum value and the deviation of the expansion / contraction length change of the lift rod cylinder detected by the detecting means. A plurality of output ratio characteristics are stored in the horizontal control means, and the sensitivity of the horizontal control is switched by switching the output ratio characteristics. An embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes a tractor provided with a pair of left and right front and rear wheels 2a and 2b at a lower portion of a body frame 3. The tractor 1 includes an engine (not shown) in a hood 4 provided at a front portion of the body frame 3. A driver's seat 6 is provided in a driving operation unit 5 which is mounted and disposed substantially at the center of the body frame 3, and a driving seat 6 is provided between the rear of the driver's seat 6 and a mounting position 7 provided at a rear part of the body frame 3. Is provided with a hydraulic device such as a hydraulic pump (not shown) and a transmission for a working machine, and a three-point link mechanism 11 including a lift arm 8, a lift arm cylinder 9, a lift rod 10, etc. In the drawing, the rotary tilling work machine A is mounted via a three-point link mechanism 11 so as to be movable up and down. At the mounting position 7, a lift rod cylinder 12, which is interposed on one of the lift rods 10 and expands and contracts, as shown in FIG. 2 (a) and FIG. Each of the oil chambers 12a and 12b is formed by a double-acting piston partitioned into a chamber 12a and an extension-side oil chamber 12b.
The rod 12c extends and retracts by controlling the flow of pressure oil from the lift rod valve 13 into and out of the lift rod valve 13. The lift rod valve 13 includes a retracting-side electromagnetic proportional control valve 13a and an extending-side electromagnetic proportional control valve 13b. Compression-side drive unit 14a and extension-side drive unit 14b that supply control currents
The horizontal control is performed via a lifting control device 15 described later. [0007] The lifting control device 15 includes a lift rod 1
0 (lift rod cylinder 12) to detect a change in the left / right attitude of the rotary tilling machine A supported by the lift rod 10 and the lift rod cylinder 12, and to the horizontal position. And a CPU as horizontal control means for controlling expansion and contraction driving of the lift rod valve 13 in accordance with a difference between the correction value for the horizontal position and the detection value of the lift rod sensor S based on the correction value for the horizontal position. When the mode switch 16 is switched from the normal mode to the adjustment mode, the mode switch 16 for switching the mode, the normal mode, and the sensitivity switching mode, and the elevating switch 17 of the rotary tilling work machine A are provided. 5 and the extension of the lift rod 10 (lift rod cylinder 12). It is configured to automatically set the operating state. That is, when the mode changeover switch 16 is switched to the "adjustment mode" side, it is first determined whether or not the traveling machine body and the work machine (rotary tilling work machine A) are in parallel. The minimum output value of the control current required to make the contraction-side electromagnetic proportional control valve 13a the maximum contraction, the minimum output value of the control current required to make the extension-side electromagnetic proportional control valve 13b the maximum extension, Control valve 13a
Are adjusted in the order of the maximum output value of the control current required for the maximum contraction and the maximum output value of the control current required for the maximum extension of the extension-side electromagnetic proportional control valve 13b. When all the adjustments have been completed, the respective adjustment values are stored in a rewritable EEPROM, and when this storage operation has been normally completed, as shown in FIG. The buzzer 18 installed on the inner surface side of the provided operation panel 6a is sounded and the buzzer 18 is notified, and then a series of adjustment modes is ended. When the setting in each of the above adjustment processes is abnormally terminated, and when the operation of storing data in the EEPROM is abnormally terminated, the buzzer 18 is caused to sound in a different sounding color, thereby allowing the operator to enter the adjustment mode. Is notified that the adjustment has not been completed normally. Each of the above adjustment values is stored as a control current range corresponding to the expansion / contraction operation range of the lift rod cylinder 12 via the retracting-side electromagnetic proportional control valve 13a and the extending-side electromagnetic proportional control valve 13b. Electromagnetic proportional control valve 13a for expansion and contraction and electromagnetic proportional control valve for extension 1
When each of the proportional control valves 13a and 13b is adjusted within the adjustment range of the control current stored independently of each other by performing the adjustment in the adjustment mode when each of the control valves 3a and 3b is adopted.
As shown in FIG. 6, for example, as shown in FIG. 6, an electromagnetic proportional control valve having a minimum value of 0.6 A of a control current for starting extension from the most retracted position and an electromagnetic proportional valve having a minimum value of 0.8 A are provided. Although the control valve is used for a tractor of the same model, the operating speed in the horizontal control range for the lift rod cylinder varies, or the actual control rod does not reach the set horizontal position before the lift rod cylinder reaches the set horizontal position. Although problems such as the stoppage of the extension operation occur, changing and storing the settings in the adjustment mode can absorb variations due to individual differences between the respective proportional control valves 13a and 13b, and provide smooth horizontal control. You can get the status. If the mode changeover switch 16 is switched to the sensitivity changeover mode after the setting change and storage in the adjustment mode as described above, the sensitivity of the horizontal control according to the traveling field condition can be changed. That is, as shown in FIG. 7, when the rotary tilling work machine A is switched to the non-working state (ascending state) after switching to the sensitivity switching mode, and the manual switch (not shown) is selectively switched, the selection operation is started. The corresponding sensitivity stage was determined, and the output ratio characteristics 1 to 5 were selected (FIG. 8).
After that, actual work traveling is performed based on the selected output ratio characteristic. Here, each of the output ratio characteristics 1 to 5 shown in FIG. 8 has a sensitivity characteristic in which the sensitivity decreases as the characteristic is switched from 1 to 5.
Automatically set to the optimum sensitivity in the field where the vehicle actually travels, such as a field where the inclination in the horizontal direction changes little by little or a field where the inclination changes greatly gradually, so that the appropriate ground for the work machine is always maintained. The control state can be maintained, and the horizontal control accuracy during work traveling can be improved. In summary, the present invention provides a detecting means for sequentially detecting the extension / contraction length of a lift rod cylinder, and a horizontal position by detecting a change in the lateral posture of a working machine supported by the lift rod cylinder. And a horizontal control means for controlling the expansion / contraction drive of the lift rod valve in accordance with the difference between the detected value of the lift rod based on the correction value to the horizontal position and the normal control mode. When the mode is switched to the adjustment mode, the control current value when the lift rod starts extending from the most retracted position is stored in the horizontal control means, and when the mode is switched to the sensitivity switching mode, the control current value is supplied to the lift rod valve. The output ratio, which varies from the minimum value to the maximum value of the control current, and the output determined by the deviation of the change in the length of the lift rod cylinder detected by the detection means. Since a plurality of force ratio characteristics are stored in the horizontal control means and the sensitivity of the horizontal control is switched by switching the respective output ratio characteristics, the electromagnetic proportional control valve of the same product type is used as the lift rod valve. In addition, by absorbing variations in control due to individual differences in the mechanical structure of each and maintaining smooth expansion and contraction control with less shock, by making more aggressive sensitivity changes regardless of the dead zone,
An extremely useful novel effect that smooth horizontal control with less shock can be maintained even when the field conditions are variously varied.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall side view of a tractor to which a rotary plow is connected. FIG. 2 (a) is a partially omitted rear view showing a configuration of a rear surface of the tractor. FIG. 3B is a side view of a main part showing an arrangement of a buzzer on the inner surface side of the operation panel of the tractor. FIG. 3 is a control system diagram for a lift rod cylinder. FIG. 4 is a control flowchart. FIG. 5 is a control flowchart following FIG. 4; FIG. 6 is a characteristic graph of operation speed-output current. FIG. 7 is a control flowchart in a sensitivity switching mode. FIG. 8 is an output ratio-deviation characteristic graph. [Description of Signs] 1 Tractor 10 Lift rod 12 Lift rod cylinder 13 Lift rod valve A Rotary tilling machine

Claims (1)

Claims: 1. A detecting means for sequentially detecting a length of expansion and contraction of a lift rod cylinder, and a correction value to a horizontal position by detecting a change in a lateral posture of a working machine supported by the lift rod cylinder. And a horizontal control means for controlling the expansion / contraction drive of the lift rod valve in accordance with the difference from the detected value of the lift rod based on the correction value to the horizontal position, and switching from the normal control mode to the adjustment mode. At this time, the control current value when the lift rod starts to elongate from the most retracted position is stored by the horizontal control means, and when the mode is switched to the sensitivity switching mode, the control current supplied to the lift rod valve is The output ratio characteristic determined by the deviation of the change in the expansion / contraction length of the lift rod cylinder detected by the detection means and the output ratio characteristic that varies from the minimum value to the maximum value of By plural stored in flat control means, the working vehicle of the lifting control device being characterized in that so as to switch the sensitivity of the horizontal control switching of the output ratio characteristics.