JPH01222705A - Electronic hydraulic pressure control device in tractor - Google Patents

Abstract

PURPOSE:To prevent shocks in stopping a lift arm in a tractor carrying out position control, by increasing pulse output in proportion to operation time of the minimum flow rate of a proportional solenoid valves of MIN line. CONSTITUTION:In control of position, a rise or drop order is sent from CPU10 in such a way that a detected value obtained by a lift arm angle sensor S1 is coincident with a set value laid by handling of a position lever I1. The order from CPU10 is sent as pulse current to a solenoid valve 13 for raising and a solenoid valve for dropping 14. When the soft arm angle reaches the neighborhood of the aimed value, in order to prevent shocks in suspension, the pulse current reduces amounts of oil in the solenoid valves 13 and 14 to the minimum range, operation time of the pulse current is increased 0.01A per second to quicken action of the lift arm and the pulse current is outputted at most five times.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an electro-hydraulic control device for a tractor, and in particular to pulse current control in the minimum flow range output to a proportional solenoid valve. It is.

[Prior Art] Conventionally, in a tractor, when there is a difference in the detection value of a lift arm angle sensor with respect to the set value of the lift arm angle set by the position lever, the hydraulic lifting mechanism is adjusted based on the difference. is controlled to raise and lower, thereby raising and lowering the lift arm.

Furthermore, in the proportional solenoid valve for driving the hydraulic mechanism, the amount of oil flowing in the minimum flow range usually varies by 21±IL at a current of 0.65 A.

[Problems to be Solved by the Invention] Therefore, in a tractor, when the lift arm is stopped, it is necessary to reduce the amount of oil flowing in the minimum flow range to below IL. If it is 11 or more, a shock will occur when the lift arm stops. Also, if controlled by pulse current using the MIN line proportional solenoid valve as a reference, the MAX
The amount of pressure oil flowing into the proportional solenoid valve in the line is 3JE, which causes a large shock when the lift arm stops. Furthermore, when the proportional solenoid valve on the MAX line is controlled using the pulse current as a reference, the amount of fluid that should flow into the proportional solenoid valve on the MIN line becomes zero, and therefore a pulse current is output to the proportional solenoid valve on the MIN line. However, the lift arm does not move up or down due to insufficient oil flowing into the lift cylinder. Therefore, when the lift arm angle approaches the position setting value and the flow rate reaches the minimum flow range, a technical problem arises that must be solved in order to prevent the shock. The purpose is to solve problems.

[Means for Solving the Problems] This invention was proposed to achieve the above object, and it uses a lift arm angle detected by a lift arm angle sensor provided on a tractor and a position set value by a position lever. In a hydraulic lifting device for a tractor that drives and controls a proportional solenoid valve according to the difference between It is an object of the present invention to provide an electro-hydraulic control device for a tractor, which is characterized in that the pulse output from a CPU is increased in accordance with the operating time of the minimum flow rate of a valve.

[Operation] In this invention, the lift arm is moved up and down so that the position set by the position lever and the detected value by the lift arm angle sensor match. At this time, when the lift arm enters a certain angle near the position setting value, M
Increase the pulse current by the minimum flow activation time of the IN line proportional solenoid valve. In such a case, the increased pulse current operates the proportional solenoid valve properly, and even in the minimum flow range, there is no shock when the lift arm stops, and the lift arm moves up and down extremely smoothly. It stops.

[Example 1] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings. For convenience of explanation, conventionally known configurations will also be explained at the same time.

As shown in Figure 2, a tractor (1) serves as a towing vehicle.
A ground work machine (2) such as a plow is connected to the left and right pair of lift arms (3) (3) at the rear of the machine, and the left and right lift rods (4)
The left and right lower links (5) swing up and down via (4).
) (5) and a top link (6) at the upper center of the work equipment connection link (7), and this work equipment connection link (7) is connected to its lift arm (3) (3).
It is configured to be lifted and lowered by a hydraulic elevator (9) which is rotated up and down by a lift cylinder (8) using hydraulic pressure. In addition, the supply and discharge control of pressure oil to the lift cylinder (8) is controlled by operating commands from a CPU (+o) configured by a microcomputer, etc. jJ and opens and closes the ascending proportional solenoid valve 0 or the descending proportional solenoid valve ω], thereby supplying the lift cylinder (8) with the pressure oil of the pump C51 and lifting the lift arm (3) ( 3) is raised, or the pressure oil in the lift cylinder (8) is discharged and the lift arm (3) (3) is lowered.

Furthermore, there is a position lever (tool) installed near the cockpit.
and the detection axis of the position meter to the lift arm (3)
The lift arm angle sensors (Sl) formed by combining the two are connected to the CPU (10) respectively, and the lift arm angle sensors (Sl) are adjusted to the set value set by operating the position lever (enginel). The CPU (10) outputs an elevating command to the ascent drive section 00 or the descent drive section Q7J so that the detected height values coincide with each other, and thereby the ascent and descent control is performed. In addition, as a draft sensor (S2) that detects tillage resistance, for example, Top Link (
A draft rod (119) connected to the front part of the draft spring (6) detects the amount of forward movement due to the plowing resistance force against the draft spring (0), for example, by using a potentiometer (sometimes detecting the amount of movement). has been done.

Furthermore, a plowing depth (drag) setting device (work 2) is provided near the cockpit, and the plowing resistance detected by the draft sensor (S2) is adjusted to the plowing resistance set value set by operating the device. The CPU (10) sends the lift drive unit 00 to the ground work machine (2) so that the detected values match.
An operation command is output to the lowering drive unit 02), thereby controlling the draft. Also, during rotary work, the draft sensor (
By using a plowing depth sensor instead of S2) and using the plowing depth/resistance setting device (T2) as the plowing depth setting device, automatic control of rotary work is performed.

Therefore, a tractor (
1) When performing work using position control, the CPU
Proportional solenoid valve 03 for ascending by operation command from Qo)
) or lowering proportional solenoid valve ■), pressure oil is supplied and discharged into the lift cylinder (8) and the lift arm (3
) is used to raise and lower the proportional solenoid valve 03)Q! I) is CPU (I
When the pulse current from n) is 0.65 A, the amount of oil flowing into the proportional solenoid valve 03) is 2.
As described above, variations in l±IL occur. Furthermore, when the lift arm (3) is stopped, it is necessary to reduce the flow oil amount to 11 or less in order to prevent the occurrence of shock in the lift arm (3). Therefore, when the lift arm (3) moves close to the target value set with the position lever (1) and enters the minimum flow rate region, the pulse current output from the CPU (10) for this minimum flow rate is applied to the corresponding actuator. The power is increased by 0.01A every second in proportion to time, and the output is output up to five times to speed up the operation of the lift arm (3) in the minimum flow range.

In addition, to explain in detail according to Fig. 3, if the proportional solenoid valve on the MIN line is controlled with a pulse current of 0.6A,
In the minimum flow range, the pressure oil is 0t, but the amount of oil flowing to the proportional solenoid valve of the MAX line is 2t. For example, at 0.65 A, 11 pressure oil flows in the MIN line, but 31 in the MAX line, resulting in a large shock when the lift arm (3) stops. So, for example, if the voltage is 0.65A and it is controlled by the MAX line, the pressure oil will flow 3 times in the MAX line, but the MIN will flow in the MAX line.
For the line type, the pressure oil is 01 and the lift arm (3
) does not move. Therefore, in the present invention, MIN
The control is performed based on the proportional solenoid valve in the line, and the pulse current is set to be slightly larger than 0.6 A in order to reduce the flow rate of pressure oil to below IL when the lift arm (3) is stopped. put. In such a case, even in the minimum flow area, if the pulse current is increased by 0.01A every second in proportion to the operating time for the minimum flow rate and output up to 5 times, the lift arm in the minimum flow rate area can be adjusted. (3
) movement becomes faster, and the flow rate of pressure oil is appropriate in the minimum flow range in the MAX line proportional solenoid valve, and the lift arm (3) quickly matches the target value.
Further, there is no shock at all when the lift arm (3) stops.

Furthermore, the operating procedure of the above embodiment will be explained according to the flowchart of FIG. First, in step (2), the detected value (output) of the lift arm angle sensor (51) is input.Furthermore, in step (2), the position position (c) is input using the position lever (II).Therefore, in step (2) In the
The output value of the pulse current is determined and output based on the difference between (a) and (c). Here, B.OUT is the output to the proportional solenoid valve, and f indicates a constant (%). Then, step (3) is reached, where it is determined whether the amount of oil flowing to each proportional solenoid valve is the minimum flow rate, and if 1
If it is 0, for example, the MAX line proportional solenoid valve is operating and the lift arm (3) quickly reaches the target value. Then, if the answer is yes in the above step (■), a timer is set in step (2), and the timer is set in step (2).
Determine whether the above a=b holds, and if
If yes, the lift arm (3) reaches the target value. If it is determined that a=b does not hold, then in step (2), the pulse current set for the minimum flow rate is increased in proportion to the operating time. The amount of increase is 0.00 for every second of the operating time. Increase OIA,
It outputs up to five times to speed up the movement of the lift arm (3). Thus, a=b, and the lift arm (
3) Move the position lever (1) to the set position,
Further, when the lift arm (3) is stopped, no shock or other phenomenon occurs, and position control is performed extremely smoothly.

[Effects of the Invention] As described in detail in the above-mentioned embodiment, the present invention provides that when the lift arm moves to the position set by the position lever, the flow rate of the pressure oil is adjusted at a certain angle near the target value. is the minimum flow area. At this time, the pulse current output from the CPU for this minimum flow rate is increased in proportion to the operating time for this minimum flow rate. Moreover, the pulse current output is based on the proportional solenoid valve on the MIN line, and the amount of pressure oil flowing into the proportional solenoid valve on the yx IN line in the minimum flow range is determined by the lift arm stoppage.
Since the throttle is sometimes below IL, no lift arm shock occurs at all. Furthermore, as mentioned above, since the proportional solenoid valve on the MIN line is used as the reference, the flow rate of pressure oil in the minimum flow range of the proportional solenoid valve on the MAX line is around 2L, so almost no shock occurs, and position control is extremely easy. It is done smoothly.

[Brief explanation of the drawing]

The figures show embodiments of the present invention, with Figure 1 being a control circuit diagram and Figure 2 being a control circuit diagram.
The figure is a side view of the tractor, FIG. 3 is a graph of the MAX line and MIN line in the minimum flow range, and FIG. 4 is a flowchart. Symbol explanation (+)...Tractor (2)...
・Ground work equipment (3)... Lift arm (4
)...Lift rod (ra)...Lower link (6)/Old...Top link (7)...
...Work equipment connection link (8)...Lift cylinder (9)...Hydraulic lifting mechanism 00...
・CPU'00・・・・・・Ascending drive part Q7J・
...Descent drive part (B) ...Proportional solenoid valve for rise (B) ...Proportional solenoid valve for descent (9) ...Pump (Eng. 1) ...Position lever (work 2) ...Plowing depth (drag force) setting device (51)
...Lift arm angle sensor (52) ...
・Draft sensor patent application Person: Iseki Agricultural Machinery Co., Ltd. Figure 3

Claims (1)

[Claims] In a hydraulic lifting device for a tractor, a proportional solenoid valve is driven and controlled according to the difference between a lift arm angle detected by a lift arm angle sensor installed on the tractor and a position set value by a position lever. , when the position of the lift arm approaches the set value and the flow rate reaches the minimum flow rate, the pulse output from the CPU is increased in accordance with the activation time of the minimum flow rate of the proportional solenoid valve on the MIN line. Electro-hydraulic control system for tractors.