JPH048205A - Hydraulic valve-controlling apparatus - Google Patents

Abstract

PURPOSE:To improve the responsibility of a proportional solenoid valve in a low-flow rate range and to enable smooth control of the valve by oscillating the smallest number of pulses to enable the driving of a proportional solenoid valve in a displacement direction free from response of hydraulic pressure. CONSTITUTION:When the difference between the value detected by a depth sensor 24 and the preset value of a tilling depth setting dial 12 is within a specific neutral range, a proportional flow control valve 6 is maintained in actuated state by outputting the smallest number of pulses not to cause the response of hydraulic pressure to a proportional solenoid and a pressure is applied to the opening force of the proportional flow control valve 6. A hydraulic pressure is applied to a lift cylinder by opening the valve 6 and the rotation angle of the lift arm is detected by a lift arm angle sensor 22, the duration of the ON time of the pulse is shortened, the electric current is corrected to a lower level, the output of the proportional flow control valve 6 is cut off and the valve is maintained in the above pressurized state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic valve control device, and can be used to control a lift arm that connects a tractor working machine and controls the elevation.

(Prior Art and Problems to be Solved by the Invention) When the lift arm of a tractor is hydraulically controlled to rise and fall, the hydraulic flow rate is changed by the operation of a proportional solenoid valve provided in the hydraulic circuit, and the hydraulic cylinder is telescopically operated. .

A proportional solenoid valve allows a current value to flow in accordance with the length of the ON time of a signal wave, and opens the valve in proportion to this current value. However, when this proportional solenoid valve begins to open,
It does not operate in proportion to the current value. The reasons for this are that the resistance value of the solenoid etc. varies depending on the temperature, that the spring of the solenoid spool varies from product to product, and that the viscosity changes depending on the oil temperature in the hydraulic circuit. The characteristics of such a proportional solenoid valve include poor responsiveness in a low flow range and a slow start of lift arm movement. Therefore, the responsiveness to small flow rate changes is also poor.

This invention eliminates such defects by maintaining the opening of the proportional solenoid valve within the range where the hydraulic pressure does not respond even when the sensor is in the dead zone, so that the dead zone can be exceeded by checking with the sensor etc. The purpose is to improve the response when there is a displacement.

(Means for Solving the Problems) The present invention provides a hydraulic valve control device configured to send and control a proportional solenoid valve that variably controls the flow rate to the minimum pulse that drives it in a direction of displacement to which hydraulic pressure does not respond. composition.

(Operation and Effects of the Invention) The hydraulic pressure from the hydraulic pump expands and contracts the hydraulic cylinder by opening the proportional solenoid valve. The opening of this proportional solenoid valve is performed by pulse generation control via a microcomputer or the like. When this proportional solenoid valve is controlled to the neutral position, the solenoid is energized by the smallest pulse that the hydraulic pressure does not respond to.
Preload acts on the operation of the proportional solenoid valve. At this time, the proportional solenoid valve is maintained in a state in which it does not open, but if the proportional solenoid valve is opened and hydraulic operation is performed, the pulse signal is corrected to decrease and the current value is lowered. , stops the output of the proportional solenoid valve and stops hydraulic operation.

When the proportional solenoid valve is switched from the neutral position to the operating range, the current value is increased from the minimum pulse generation state where the preload state is maintained as described above to the pulsed current value for operating the proportional solenoid valve. However, due to this increase in current value, the solenoid valve opens proportionally, increasing the hydraulic pressure range and improving the responsiveness of the proportional solenoid valve in the small flow range, improving followability.
Smooth control with little tension can be performed. Further, with this configuration, the proportional solenoid valve can be operated by software on the controller side without having to have a special configuration or form, so that it can be an inexpensive configuration.

(Example) In FIGS. 1 to 4, a case is shown in which the hydraulic valve control device of the present invention is applied to a hydraulic valve of a lift arm that controls the elevation of a working machine of a tractor.

In FIGS. 1 and 2, a tractor body 1 has a pair of left and right front wheels 2 and a rear wheel 3, and has a four-wheel drive configuration in which the vehicle is powered by an engine 4 mounted at the front.

Below the rear cockpit 5, there are a proportional flow control valve 6 in the hydraulic circuit of the lift cylinder, a horizontal control valve 7 in the hydraulic circuit of the rolling cylinder, a slope sensor 10 for detecting the horizontal tilt angle of the vehicle body 1, etc. is arranged to allow the lift arm 8 at the rear end to move up and down.

Further, on the sideways rear wheel fender 9 of the cockpit 5, there is a tilt adjustment dial 11 for changing and adjusting the left and right mounting angle of the slope sensor 10 with respect to the vehicle body 1, and a plowing dial 11 for setting the working depth of the working machine with respect to the soil surface. A depth setting dial 12, a position lever 13 for operating or adjusting the ascending position of the working machine 14, and the like are arranged.

Further, a pair of left and right lower links 15 and a top link 16 are provided at the rear of the vehicle body 1 to connect the working machine 14, and the working machine 14 is provided at the rear end of these, for example, tilling claws 17.
A tilling device 18 having a power extraction shaft 19 is connected to the tilling device 18, and the tilling device 18 is driven and rotated by a power take-off shaft 19. A rolling cylinder 20 that is controlled to expand and contract by hydraulic pressure is provided between the left and right lower links 15 and the top link 16.
By expanding and contracting the rolling cylinder 20, the left and right lower links 15 are moved up and down, and the work implement 14 can be rolled left and right with respect to the vehicle body 1. A stroke sensor 21 detects the amount of expansion and contraction of the left and right rolling cylinders 20 or the vertical movement angle of the lower link 15. A lift arm angle sensor 22 is provided at the base of the lift arm 8 to detect the vertical movement angle of the lift arm 8.

A depth sensor 24 is installed at the base of a leveling plate 23 located at the rear of the tilling device 18 for leveling the tillage mark, and detects the vertical movement angle of the leveling plate 23 with respect to the main body of the tilling device 18 to detect the plowing depth. It is set up.

25 is a steering wheel.

The above-described position lever 13, plowing depth setting dial 12, tilt adjustment dial 11, lift arm angle sensor 22, depth sensor 24, stroke sensor 21, and slope sensor 10 are input to the controller having a microcomputer CPU. a lift arm 8 having a proportional solenoid valve, a proportional flow control valve 6 for lifting;
The mouth-ring cylinder 20 is configured to output a horizontal control valve 7 that expands and contracts. Reference numeral 26 denotes a mode switch for changing control modes, such as depth control for automatically maintaining the working machine 14 at a set plowing depth, position control for controlling the working machine 14 to rise to a certain height, and other controls. Can be switched.

For horizontal control, when the slope sensor 10 detects an inclination angle of the vehicle body 1 in the left-right direction that is more than a certain level, the horizontal control valve is output, and the left and right rolling cylinders 20 expand and contract to control the slope by the amount of inclination detected by the slope sensor 10. The working machine 14 is rolled to maintain and control the working posture of the working machine 14 horizontally.

In the depth control, the lift arm 8 is moved up and down according to selection by the mode switch 26 so as to maintain the plowing depth set by the plowing depth setting dial 12, and feedback control is performed by the depth sensor 24.

In such depth control, as shown in FIG. 3, by reading the plowing depth setting dial 12 and reading the depth sensor 24, the difference between the read value of the depth sensor 24 and the set value of the plowing depth setting dial 12 is set to a constant neutral state. When in the region of position (N=1), by outputting the least unresponsive pulse of oil pressure to the proportional solenoid (e.g. 0.5 amps) to maintain the proportional flow control valve 6 in the actuated state. A preload is applied to the opening force of the proportional flow control valve 6. At this time, when the proportional flow rate control valve 6 opens, hydraulic pressure is applied to the lift cylinder, and when the lift arm angle sensor 22 detects the amount of rotation of the lift arm 8, the ON time length of the pulse at this time is reduced and the current is The output of the proportional flow control valve 6 is adjusted to ○FFL by lowering the value.
, the preload state is maintained and controlled.

Also, when the difference between the read value of the depth sensor 24 and the set value of the plowing depth setting dial 12 is within the range of the neutral position N (
N = 1) or outside the area of the neutral position N (N
= 0), etc., constant depending on the ON type length of the output pulse in the ascending or descending direction (e.g. 0.6 ampere)
When the current is output to the above current value, the proportional flow rate control valve 6, which has been maintained and controlled as described above, is immediately opened.
Lift arm 8 is activated.

In the graph showing the relationship between the difference between the plowing depth set value and the detected value by the depth sensor 24 as a displacement value in the upward and downward directions in FIG. = 1, the change in current value is up to 0.5 amperes, and the neutral position (N = 1)
Assuming that the current value other than (N = 0) is 0.6 ampere,
The output correction of the proportional flow rate control valve 6 is io, 6-0.
This is done by changing the current value around 5=0.1 ampere. That is, the ON time at the neutral position N=1 is determined by monitoring whether or not the tilling device 18 is actually operated by the output current value according to this ON time, and determining whether the tilling device 18 is raised or lowered. For example, by decreasing this ON time, the operating pre-pressure of the proportional flow rate control valve 6 is maintained and controlled.

In FIGS. 1, 2, and 5, the tilling device 18
A sensor for detecting normal rotation and reverse rotation of the plowing machine and a switch 27 are provided to detect the operation in reverse and automatically switch the control mode from depth control, which performs automatic plowing depth control, to position control. When the rotation is returned to normal, it is configured to automatically return to the original mode.

Reversing PT○, which can reverse the working equipment 14 such as the tilling device 18, is used to flatten the soil at the ridge.
In order to reverse the rotation of O and move the tilling device 18 forward while cultivating shallowly, the tilling depth is adjusted by position control operation. It was necessary to switch to position mode, which made the operation complicated. By automatically switching to position mode during reverse rotation, the above operation can be omitted.

In this way, the switch 27 that detects the position of the reverse rotation PT○
When switching from normal rotation to reverse rotation during deep plowing work, if depth control was previously used, this depth control is automatically cut and automatically switched to position control, and
Operability can be improved by configuring to automatically return to depth control when switching from reverse rotation to forward rotation.

[Brief explanation of the drawing]

The figures show an embodiment of the invention, and Figure 1 is a side view;
FIG. 2 is a block diagram, FIG. 3 is a flowchart, FIG. 4 is a graph showing ON time characteristics of a proportional solenoid valve, and FIG. 5 is a partial flowchart. (Explanation of symbols)

Claims (1)

[Claims] A hydraulic valve control device configured to control a proportional solenoid valve that variably controls the flow rate to emit and control the minimum pulse that drives it in a direction of displacement to which hydraulic pressure does not respond.