JP2855779B2 - Hydraulic valve control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic valve control device, and can be used for controlling a lift arm for controlling a lifting operation by connecting a tractor working machine.

(Prior Art and Problems to be Solved by the Invention) When raising and lowering the lift arm of a tractor hydraulically,
The operation is performed by changing the hydraulic flow rate by operating a proportional solenoid valve provided in the hydraulic circuit to extend and retract the hydraulic cylinder.

The proportional solenoid valve supplies a current value according to the length of the ON time of the signal wave, and opens the valve in proportion to the current value. However, when we started to open this proportional solenoid valve,
It does not work in proportion to the current value. This is because the resistance value of the solenoid or the like fluctuates depending on the temperature, the spring of the solenoid spool varies from product to product, and the viscosity changes depending on the oil temperature in the hydraulic circuit. As characteristics of such a proportional solenoid valve, there are disadvantages that the response in a small flow rate region is poor and the lift arm starts to move slowly. Accordingly, the response to a small change in the flow rate is also poor.

The present invention solves such a defect, and maintains the opening of the proportional solenoid valve in a region where the hydraulic pressure does not respond even when the sensor is in the dead zone.
When there is a displacement exceeding the dead zone as detected by a sensor or the like, the response is to be improved.

(Means for Solving the Problems) The present invention provides a hydraulic valve control device that is set to transmit a small amount of pulses that are driven in a displacement direction in which hydraulic pressure does not respond to a proportional solenoid valve that variably controls a flow rate. Configuration.

(Operation and Effect of the Invention) The hydraulic pressure from the hydraulic pump causes the hydraulic cylinder to expand and contract by opening the proportional solenoid valve. The opening of the proportional solenoid valve is performed by pulse transmission control via a micro computer or the like. When the proportional solenoid valve is controlled to the neutral position, a current flows through the solenoid by the minimum pulse transmission that does not respond to the hydraulic pressure, and a preload acts on the operation of the proportional solenoid valve. At this time, the proportional solenoid valve is maintained without being opened, but if the proportional solenoid valve is opened and hydraulic operation is performed, the pulse signal is corrected to decrease at this time, and the current value is reduced. Stop the output of the proportional solenoid valve, and stop the hydraulic operation.

When the proportional solenoid valve is switched from the neutral position to the operation range, the current is increased from the minimum pulse transmission state maintained in the preload state to the current value by the pulse for operating the proportional solenoid valve. However, this increase in the current value opens the solenoid valve proportionally, increasing the hydraulic flow area, improving the responsiveness of the proportional solenoid valve in a small flow rate area, improving the followability, and improving the high A small and smooth control can be performed. In addition, with such a configuration, the proportional solenoid valve can be operated by software on the controller side without using a special configuration or form, so that an inexpensive configuration can be achieved.

(Embodiment) FIGS. 1 to 4 show a case where the hydraulic valve control device of the present invention is used for a hydraulic valve of a lift arm that controls lifting and lowering of a working machine of a tractor.

1 and 2, the tractor body 1 has a four-wheel drive configuration having a pair of left and right front wheels 2 and a rear wheel 3 and driven by an engine 4 mounted on a front portion. Below the cockpit 5, a proportional flow control valve 6 in a hydraulic circuit of a lift cylinder, a horizontal control valve 7 in a hydraulic circuit of a rolling cylinder, and a slope sensor 10 for detecting an inclination angle of the vehicle body 1 in the left-right direction. And the like, so that the lift arm 8 at the rear end is vertically moved.

The rear wheel fender 9 on the side of the cockpit 5 has an inclination adjusting dial 11 for changing and adjusting the right and left mounting angles of the slope sensor 10 with respect to the vehicle body 1, and a plow 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 raised position of the work implement 14, and the like are arranged.

Further, a pair of left and right lower links 15 and a top link 16 for connecting the working machine 14 are provided at a rear portion of the vehicle body 1, and the working machine 14 is provided at the rear end portion of the working machine 14, for example, with a tilling claw 17. 18 and the power take-out shaft 19
For transmission rotation. 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, and the left and right lower links 15 are moved up and down by the expansion and contraction of the rolling cylinder 20, so that the work implement 14 is mounted on the vehicle body. 1 can be rolled left and right. A stroke sensor 21 detects the amount of expansion and contraction of the left and right rolling cylinders 20 and the vertical rotation angle of the lower link 15. A lift arm angle sensor for detecting a vertical rotation angle of the lift arm 8 is provided at a base of the lift arm 8.
22 are provided.

Leveling plate at the rear of the tilling device 18 to level the tilling track
At the base of 23, a depth sensor 24 for detecting the vertical rotation angle of the leveling plate 23 with respect to the tillage device 18 and detecting the plowing depth is provided.
Is provided.

 25 is a steering wheel.

The controller having the microcomputer CPU includes the position lever 13, the tillage setting dial 12, the tilt adjustment dial 11, the lift arm angle sensor 22, and the like as described above.
The depth sensor 24, the stroke sensor 21, and the slope sensor 10 are input to output a lift arm 8 having a proportional solenoid valve, a proportional flow control valve 6 for raising and lowering, a horizontal control valve 7 for expanding and contracting the rolling cylinder 20, and the like. . Reference numeral 26 denotes a mode switch for switching a control mode, which includes a depth control for automatically maintaining and controlling the work implement 14 at a set plow depth, a position control for controlling the work implement 14 to rise to a certain height, and other controls. Can be switched.

In the horizontal control, the slope sensor 10 detects a tilt angle of the vehicle body 1 in the left-right direction that is equal to or greater than a certain angle, and outputs a horizontal control valve. Work machine 14
And the work posture of the working machine 14 is maintained and controlled horizontally in the left-right direction.

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

In such depth control, as shown in FIG. 3, the difference between the read value of the depth sensor 24 and the set value of the tillage depth setting dial 12 is constant by reading the tillage depth setting dial 12 and reading the depth sensor 24. When in the position range (N = 1), the hydraulic pressure is output to the proportional solenoid with the minimum pulse that is not responded (for example, 0.5 amps), and the proportional flow rate control valve 6 is maintained in the driven state, so that the proportional flow rate is maintained. A preload is applied to the opening force of the control valve 6. At this time, when the proportional flow control valve 6 is opened, the hydraulic pressure acts on 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 reduced. The output of the proportional flow rate control valve 6 is turned off by decreasing the value, and the preload state is maintained and controlled.

Also, the reading value of the depth sensor 24 and the till depth setting dial
When the difference from the set value of 12 is within the range of the neutral position N (N
= 1), when the current is outside the range of the neutral position N (N = 0), etc., when a current value that is constant (for example, 0.6 amperes) or more is output depending on the ON type length of the output pulse in the ascending or descending direction. The proportional flow control valve 6 maintained and controlled as described above is immediately opened, and the lift arm 8 is operated.

In the graph showing the relationship between the ON time length (or current value) and the difference between the tillage depth setting value and the value detected by the depth sensor 24 in FIG. When the change in the current value at N = 1 is up to 0.5 amperes and the current value other than the neutral position (N = 1) (N = 0) is 0.6 amperes, the output correction of the proportional flow control valve 6 is about 0.6-0.5. = 0.1 Amperes. That is, the ON time at the neutral position N = 1 is determined by the controller monitoring whether or not the actual operation of the tilling device 18 has been performed based on the output current value based on the ON time, and the tilling device 18 moves up or down. For example, by reducing this ON time, the operation preload of the proportional flow control valve 6 is maintained and controlled.

In FIGS. 1, 2 and 5, the tilling device 18
Provision of a sensor for detecting normal rotation and reverse rotation of the switch, and a switch 27 to detect that the operation has been performed in the reverse direction, and change the control mode to
The depth control for performing the automatic plowing depth control is automatically switched to the position control, and when returning to the normal rotation, the mode is automatically returned to the original mode.

The reversing PTO, which can reverse the working machine 14 such as the tilling device 18, reverses the rotation of the PTO in order to flatten the ridge of the furrow, and to advance the tilling device 18 while tilling the tilling device 18 shallowly. To adjust the plowing depth with
Until now, when the automatic plowing depth was used, it was necessary to switch from the automatic plowing depth (depth) mode to the position mode, and the operation was complicated. By automatically setting the position mode at the time of reverse rotation, the above operation can be omitted.

In this way, when the switch 27 for detecting the position of the reverse rotation PTO is switched from normal rotation to reverse rotation during the plowing operation,
If depth control was previously performed, the depth control is automatically cut and automatically switched to position control, and when switching from reverse rotation to forward rotation, depth control is automatically returned to operation. Performance can be improved.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 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,
FIG. 5 is a partial flowchart. (Explanation of symbols) 6 proportional flow control valve, 8 lift arm, 12 depth setting dial, 24 depth sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) A01B 63/00-63/12 F16K 31/06

Claims (1)

(57) [Claims] 1. A hydraulic valve control device wherein a proportional solenoid valve for variably controlling a flow rate is set to transmit and control a minimum pulse for driving in a displacement direction in which no hydraulic pressure responds.