JPH082B2 - Tractor lift control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working machine lifting control apparatus for a tractor, and an object thereof is to obtain a working machine lifting control apparatus with improved working accuracy.

[0002]

2. Description of the Related Art A solenoid valve for ascending that controls the supply of pressure oil to a lift cylinder of a work machine lifting mechanism and a solenoid valve for descending that controls the discharge of pressure oil from a lift cylinder are conventionally known as electromagnetic solenoid valves. Since the valve portion that opens and closes at a constant opening degree according to energization and de-energization is used, the flow rate of the pressure oil supplied to and discharged from the lift cylinder per unit time is always constant.

When such a valve is used to perform the plowing depth control, that is, the so-called depth control, the pressure oil of the entire flow rate is suddenly supplied or cut off every time an ON / OFF control signal is output from the control section. However, there is a problem that a large impact is generated and an occupant feels uncomfortable, but the plowing depth varies and the plowing depth is unstable. More specifically, in depth control, the rear cover is slidably contacted with the ground and its vertical rotation is electrically fed back to the hydraulic lifting mechanism to keep the working depth constant. , OFF signal is output from the control unit composed of the microcomputer, the movement of the hydraulic lifting mechanism becomes jerky, and hunting may occur in some cases. In particular, when a signal is issued in the direction of lowering the rotary tiller, the ground receives the tilling part of the rotary tiller, so that a large change in the working depth does not occur, but the rotary tiller is raised. When the direction signal is output, the load is in the direction of unloading, so if the entire flow rate of pressure oil is flowed even for a short time, the rotary tiller will greatly rise, and the working depth will be set. There was a problem that it greatly deviated from the depth.

[0004]

The present invention is proposed in view of the above problems, and the following technical means have been taken. That is, in the tractor that controls the working depth by rotating the rear cover 33 of the rotary tiller 4 connected to the rear of the machine body up and down to electrically feed back the vertical movement to the hydraulic lifting mechanism. A plowing depth setting device 28 for setting the plowing depth and a plowing depth detector S ₂ for detecting the plowing depth of the tilling part are connected and provided on the input side of the constituting micro computer 29. On the output side, an ascending proportional solenoid valve 26 and a descending proportional solenoid valve 22 whose flow rate is controlled in proportion to the magnitude of an electric signal are connected, and the construction of a working machine lifting control device for a tractor. And

[0005]

Embodiments of the present invention will be described below based on the embodiments shown in the drawings. The hydraulic control circuit is shown in FIG. 1 and a side view of the working machine in use is shown in FIG. 2. The hydraulic control circuit is connected to the left and right lower links 2 and 2 of the tractor 1 and a link mechanism such as a top link 3. The rotary tiller 4 serving as a working machine is rotated by rotating the lift arms 7 and 7 up and down by the operation of the lift cylinder 6 of the working machine lifting mechanism 5.
This is for raising or lowering the tarry tiller 4. In this embodiment, the lift cylinder 6 and the lift arm 7 constitute a hydraulic lifting mechanism.

The lift cylinder 6 is connected to the valve chamber 10a of the check valve 10 via the throttle valve 8 and the oil passage 9, and the pilot valve 13 with the oil passage 12 facing the tank 11 is moved to the valve chamber 10a. Also, the oil passage 15 is provided to the back chamber 10b of the check valve 10.
The ascending valves 16 connected to each other via the oil passages 17 so that the opening areas of the valve holes are controlled in proportion to the pressure applied to the pilot portion 16a are connected to the valve chamber 10a via the oil passage 17. Adjustment valve 18 in which the opening area of the valve hole is controlled in proportion to the magnitude of the control current flowing through the valve
To the hydraulic pump 20 via the oil passage 19 and the oil passage 21.
The proportional proportional solenoid valve 22 for lowering, which is connected to the pilot portion 16a via the solenoid valve and controls the opening area of the valve hole in proportion to the magnitude of the control current supplied to the electromagnetic solenoid portion 22a, is connected to the valve chamber 10a. In the oil passage 23, again, the tank 11
To the hydraulic pump 20 and the oil passage 25 to the hydraulic pump 20, respectively.
Is connected to the raising valve 16 to form a raising proportional solenoid valve 26 including the raising valve 16 and the adjusting valve 18.

Now, when the electromagnetic solenoid portion 13a of the pilot valve 13 is not energized, the communication port 13 as shown in FIG.
Since the valve chamber 10a and the back chamber 10b communicate with each other by b and the oil passages 14 and 15, the valve body 10c of the check valve 10 has the spring 10d.
The valve chamber 10a is cut off from the oil passage 17 by the check valve 10 and the pressure oil in the lift cylinder 6 is held by the check valve 10 in a neutral state. Further, the solenoid valve 22a of the proportional solenoid valve 22 for lowering and the adjusting valve 18 are provided. The electromagnetic solenoid portion 18a is non-energized.

Electromagnetic solenoid 13 of pilot valve 13
When a is energized, the drain port 13c is switched and the back chamber 10b is communicated with the tank 11 via the oil passage 12,
The valve body 10c is opened by the pressure oil of the lift cylinder 6 guided to the valve chamber 10a so that the oil passage 9 and the oil passage 23 communicate with each other, and when the electromagnetic solenoid portion 22a of the descending proportional solenoid valve 22 is energized. , The lowering port 22b communicates with the oil passages 23 and 24, so that the pressure oil in the lift cylinder 6 receives the throttle valve 8, the oil passage 9, the valve chamber 10a, the oil passage 23, and the lowering port.
The lift arms 6 and 7 are discharged to the tank 11 through the valve 22b and the oil passage 24, and the lift piston 6a retracts toward the lift cylinder 6, so that the lift arms 7 and 7 are rotated downward by their own weight, and the electromagnetic Since the valve hole of the lowering proportional solenoid valve 22 opens in proportion to the magnitude of the control current of the solenoid portion 22a, the hydraulic oil is discharged from the lift cylinder 6 at a flow rate proportional to the control current, and the lift arm 7, 7 descends at a speed proportional to the control current, and the electromagnetic solenoid portion 18a of the regulating valve 18 is not energized during this descending operation.

Adjustment valve 18 of proportional solenoid valve 26 for raising
The electromagnetic solenoid portion 18a of the
1 is connected to the tank 11 by the oil passage 27 as shown in FIG. 1, but when the electromagnetic solenoid 18a is energized, the oil passage 19 is connected to the oil passage 21 via the adjusting valve 18, The pressure oil of the hydraulic pump 20 is the oil passage 19 and the adjusting valve 1.
8 and the oil passage 21 are sequentially supplied to the pilot portion 16a, and the ascending port 16b of the ascending valve 16 connects the oil passage 25 and the oil passage 17 to each other, so that the valve body 10c is resisted against the spring 10d.
The pressure oil sent from the hydraulic pump 20 is supplied to the lift cylinder 6 via the oil passages 25 and 17, the valve chamber 10a, the oil passage 9 and the bypass passage 8a, and the lift piston 6a is moved from the lift cylinder 6 to the lift cylinder 6a. Lift and lift
The frames 7 and 7 will rotate upward.

In this case, since the valve hole of the adjusting valve 18 is opened in proportion to the magnitude of the control current of the electromagnetic solenoid portion 18a,
The pressure oil whose flow rate is proportional to the control current is pilot portion 16a.
The valve hole of the ascending port 16b is opened in proportion to this flow rate supplied to the pilot portion 16a, so that the pressure oil of the oil pump 20 has a flow rate proportional to the magnitude of the control current. 6 will be supplied.

Therefore, the rising speed of the lift arms 7, 7 is controlled according to the magnitude of the control current. The control circuit of the working machine lifting mechanism 5 illustrated in FIG.
The raising / lowering position setting device I made of a rotary potentiometer, whose detection shaft is turned by the turning operation of the raising / lowering operation dial 28, and the raising / lowering operation of the lift arm 7 turn the detecting shaft. Ascending / descending position sensor S ₁ composed of a rotary potentiometer is used as a microcomputer.
The input device 30 of the input / output device 29 of the input / output device 29 is used to input the pressure control valve to the output device 32 so that the set value of the ascending / descending position setter I matches the detection value detected by the ascending / descending position sensor S ₁ . 18 and the electromagnetic solenoid portions 18a and 22a of the lowering proportional solenoid valve 22 are controlled, and a position control system is configured here.

Further, in order to adjust the ascending / descending speed in the ascending / descending control by the ascending / descending operation dial 28, there are provided an ascending speed setting device U and a descending speed setting device D, each of which is composed of a rotary potentiometer. By adjusting the resistance value, the magnitude of the control current supplied to the electromagnetic solenoids 18a and 22a is adjusted. Next, the depth control system (plow depth control system) will be described. The depth control is intended to catch the unevenness of the ground by swinging the rear cover 33 and feed it back to the microcomputer 29 to control the working machine up and down to maintain a predetermined working depth. Is.

Therefore, the tilling depth sensor S ₂ attached to the rotary tilling device 4 is input to the input device 30, and the tilling depth detection value by the tilling depth sensor S ₂ coincides with the tilling depth setting value by the operation dial 28. As described above, the control valve 18 and the proportional lowering solenoid valve 22 are each excited to perform the depth control. In this embodiment, one setting device 28 is used for both the position control and the depth control. , Are selectively changed by the change-over switch 34.

Further, when the rotary tiller 4 is lowered, the descending speed is controlled so as to be temporarily gentle from before the ground of the tiller 34 to when it digs into a certain depth under the ground. when the detection value by the vertical position sensor S ₁ is reached in a range, and configured so as to reduce the control current of lowering proportional solenoid valve 22 temporarily by the computation unit 31 of the program Deserare - to Deployment function works I have to.

Thus, the above-mentioned device can freely adjust the rising speed and the descending speed of the rotary cultivating device 4 by adjusting the magnitude of the electric signal. Therefore, for example, during the lowering operation, the rotary cultivating device is used. A check valve in which the control valve is controlled by the pilot valve 13 while the gradual lowering speed is taken into consideration in consideration of the weight of the device 4 or stalling due to a sudden increase in load is prevented. Leakage from the lift cylinder 6 via 10 is blocked by this check valve 10 and an accurate holding function is ensured.

The ascending proportional solenoid valve 26, the descending proportional solenoid valve 22, the pilot valve 13 and the like may have the same functions as those shown in the drawing, for example, the ascending proportional solenoid valve. 26 is a regulating valve 18
The valve 16 for raising and the valve 16 may be integrally provided. As the control circuit of the working machine lifting mechanism 5, various circuits can be used other than the one illustrated in FIG.

[0017]

The working machine lifting control apparatus according to the present invention is constructed as described above, and the working depth setting device 28 is always provided.
Based on the deviation while comparing the set value by the sensor S ₂ for detecting the working depth with the detected value, the magnitude of the current flowing through the proportional solenoid valve is controlled to supply pressure oil to the lift cylinder 6. Since the supply is controlled or the discharged oil is controlled, delicate elevation control can be performed, and the plowing depth can be adjusted accurately.

Particularly according to the present invention, the rear cover 33
However, when it is detected that the plowing depth becomes deep, the rotary tilling device 4 does not suddenly rise unlike the conventional device, and slowly rises in accordance with the deviation in the area of a minute deviation. Therefore, it is possible to secure a stable tilling depth with little fluctuation in tilling depth. Further, in that case, the proportional solenoid valve 2 for raising
6 is an adjusting valve 18 for controlling the flow rate in proportion to the magnitude of the control current, and an ascending valve 16 whose opening is adjusted by the adjusting valve 18.
Since it is composed of and, the flow rate control proportional to the deviation is surely performed, and more stable plowing depth control becomes possible.

[Brief description of drawings]

FIG. 1 is a hydraulic control circuit diagram.

FIG. 2 is a side view of a usage state.

FIG. 3 is a control block diagram.

[Explanation of symbols]

 4 Rotary Tillage Device 6 Lift Cylinder 10 Check Valve 10b Back Chamber 13 Pilot Valve 16 Ascending Valve 18 Adjusting Valve 20 Hydraulic Pump 22 Proportional Solenoid Valve for Lowering 26 Proportional Solenoid Valve for Ascending 29 Micro Computer 33 Rear Cover

Claims (1)

[Claims] 1. A tractor for controlling tillage depth by vertically rotating a rear cover 33 of a rotary tiller 4, which is connected to a rear portion of an airframe, to electrically feed back the vertical movement to a hydraulic lifting mechanism. On the input side of the micro computer 29 constituting the control unit, a plowing depth setting device 28 for setting the plowing depth and a plowing depth detector S ₂ for detecting the plowing depth of the tilling part are connected and provided. A rising proportional solenoid valve 26 and a descending proportional solenoid valve 22 whose flow rate is controlled in proportion to the magnitude of the electric signal are connected to the output side of the controller 29, and the rising proportional solenoid valve 26 is controlled. Large current
Regulating valve 18 for controlling the flow rate in proportion to the magnitude and the regulating valve 18
A working machine lifting control device for a tractor, which comprises a rising valve 16 whose opening degree is adjusted by