JPH0536325Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a hydraulic lifting control device for a tractor that controls the lifting and lowering of a plow.

[Prior art and its problems] Conventionally, this type of device detects the compressive force applied to the top link or the tensile force applied to the lower link of the three-point link mechanism connecting the plow, and The displacement force is mechanically or electrically fed back to the control valve of the hydraulic lifting system, and when it exceeds a predetermined value,
It is known that this control valve is switched to the "up side" to move the lift arm upward. When performing reverse plowing with a plow using such conventional equipment, the tractor is usually brought close to the edge of the ridge, and then the hydraulic control lever for drafting is operated to the lowest position to land the plow on the ground. However, after the machine moves forward and the plow penetrates into the soil, the hydraulic control lever is again raised slightly to set the desired traction setting.

In this way, the initial operation for plowing is to operate the hydraulic control lever once to the lowest position.
This is to shorten the distance from the starting point of plowing until reaching a predetermined plowing depth, the so-called plowing distance.

Further, as a publication disclosing the prior art, there is one described in, for example, Japanese Patent Application Laid-Open No. 58-43707.
The device described in this publication is equipped with a control unit that operates the hydraulic lifting mechanism in the downward direction for a certain period of time, so if the aircraft is stopped or the forward speed of the aircraft is slow, the plow will not move. The disadvantage is that the timer goes off before the plow goes into the soil, and the plow does not plow properly.

[Means for solving the problems] This invention was proposed in view of the above-mentioned problems, and the following technical measures were taken.

That is, a lift switch that raises and lowers the plow connected to the rear of the aircraft body, a distance detection sensor that detects the forward distance of the aircraft body, a draft setting means that sets the traction resistance applied to the plow, and a draft setting device that detects the traction resistance applied to the plow. A tractor comprising a draft sensor and configured to maintain a plow at a set traction resistance value while comparing a set value set by a draft setting means and a detected value detected by the draft sensor, A predetermined current is applied to the lowering solenoid valve of the hydraulic lifting system control valve from the time when the lift switch is operated to the lowering side until the distance detection sensor detects that the aircraft has moved forward a predetermined distance. This is a hydraulic lifting/lowering control device for a tractor, characterized in that it is equipped with a control means for rapidly lowering the plow.

[Example] Hereinafter, an example of this invention will be described based on the drawings. First, to explain the structure, 1 is a self-propelled tractor having front wheels 2 and rear wheels 3. An engine 4 is mounted on the front part of the body, and a clutch housing 5 and a transmission case 6 are connected to the rear part. The aircraft is configured with A hydraulic cylinder case 7 is fixed to the upper part of the transmission case 6, and lift arms 8, 8 are rotatably pivotally attached to both left and right sides of the hydraulic cylinder case 7. In this embodiment, a hydraulic cylinder (not shown) in the hydraulic cylinder case 7 and the lift arms 8 constitute a hydraulic lifting mechanism.

9 is a top link, 10, 10 is a lower link, and 13, 13 is a lift rod. A plow 12 is connected to the rear of a three-point link mechanism 11 consisting of a top link 9 and a lower link 10, 10, and the plow 12 is rotated up and down by rotating the lift arms 8, 8. . 14 is a mast of the plow 12.

Furthermore, a lift arm angle sensor 15 composed of a potentiometer for detecting the rotation angle of the lift arms 8, 8 is installed on one side of the pivot shaft of the lift arms 8, 8, and is installed on the front side of the top link 9. The pivot part is provided with a draft sensor 16 that detects the magnitude of traction resistance when the pivot part is pushed from behind, and the rear axle part is provided with a draft sensor 16 that detects the rotation speed of the axle 17 of the rear wheels 3, 3. A wheel rotation sensor 18 is provided for determining the forward distance of the aircraft. On the side of the cockpit are a position lever 19 that determines the elevation position of the work equipment and a draft lever 2 that serves as a draft setting means to set the traction resistance value applied to the plow.
0 is provided, and potentiometers 19a and 20a arranged at the bottom of both levers 19 and 20,
It is configured so that the rotational position of the lift arms 8, 8 and the draft force can be set.

Therefore, when the position lever 19 is rotated, the lift arms 8, 8 move up and down to the position corresponding to the position of the position lever 19, and in the case of the draft lever 20, this draft lever 2
The draft force can be set by rotating the draft lever 20 in the vertical direction, and the draft setting value decreases as the draft lever 20 is pulled up.

Further, an elevating switch 22 for elevating and lowering the plow 12 is provided on the upper part of the fender 21 on one side that covers the rear wheel 3, and this elevating switch 22 has priority regardless of the set positions of the position lever 19 and the draft lever 20. It works to raise or lower a working machine such as a plow connected to the rear of the tractor 1.

FIG. 2 shows the control system of the hydraulic lift control device, in which the lift arm angle sensor 15, draft sensor 16, wheel rotation sensor 18, position potentiometer 19a, and draft potentiometer 20a are respectively A. /D converter 23
It is connected to a control device 24 consisting of a CPU.

The lift switch 22 is directly connected to the control device 24 without passing through the A/D converter 23.

An ascending proportional solenoid valve 25 and a descending proportional solenoid valve 26, which are control valves that control the hydraulic lifting mechanism, are connected to the output side of the control device 24. Rising proportional solenoid valve 25, lowering proportional solenoid valve 2
6, the opening degree of the spool of the control valve is controlled according to the magnitude of the current value applied to the solenoid, and the flow rate is controlled so that the lifting speed of the lift arms 8, 8 can be changed.

Next, the operation of this device will be explained based on the flowchart shown in FIG.

The lift switch 22 is used to perform draft control.
When it is operated to the "downward" side, a preset maximum current is applied to the solenoid of the descending proportional solenoid valve 26, and the spool opens to the maximum, causing the plow 12 to rapidly descend. At this time, the aircraft is moved forward to begin plowing.

By pressing the lift switch 22, a descending command is issued, and the distance measurement counter (provided in the control device 24) based on the integration of the wheel rotation sensor 18 is first cleared, and then the rotation of the rear wheel 3 is cleared. This wheel rotation sensor 18 detects and calculates the forward distance of the tractor 1.

At this time, the maximum current is applied to the solenoid of the lowering proportional solenoid valve 26 until the tractor 1 has traveled a certain distance, the spool is set to a nearly fully open state, and the lift arms 8 are rapidly lowered (step). .

Then, when the tractor 1 travels a certain distance, draft control is started and the draft lever 2
Setting value set by 0 and draft sensor 1
A comparison is made with the detected value detected by 6, and the current value flowing through the solenoids of the ascending or descending proportional solenoid valves 25 and 26 is controlled based on the difference between the set value and the detected value, that is, the deviation. That is, when the detected value is smaller than the set value, an output command is issued to the descending proportional solenoid valve 26 based on the deviation (step), and conversely, when the detected value is larger than the set value, Then, an output command is issued to the ascending proportional solenoid valve 25 based on the deviation (step).

In this way, the tractor 1 moves a certain distance from the edge of the ridge.
Until the plow is traveling, the spool of the hydraulic lifting system control valve is set fully open to the descending side to bring the plow 12 down rapidly to the ground, and after traveling a certain distance, the plowing depth is shifted to the set plowing depth determined by the draft lever 20. Since draft control is to be continued, in order to shorten the plowing distance, operate the lever as previously done, in other words, initially operate the draft lever downward to the lowest position.
Thereafter, the troublesome operation of pulling up the draft lever slightly becomes unnecessary, and this makes turning operations at the edge of the ridge and hydraulic lifting and lowering operations easier.

[Effects of the invention] Since this invention is configured as described above, it has the following technical effects.

That is, a lift switch that raises and lowers the plow connected to the rear of the aircraft body, a distance detection sensor that detects the forward distance of the aircraft body, a draft setting means that sets the traction resistance applied to the plow, and a draft setting device that detects the traction resistance applied to the plow. A tractor comprising a draft sensor and configured to maintain a plow at a set traction resistance value while comparing a set value set by a draft setting means and a detected value detected by the draft sensor, A predetermined current is applied to the lowering solenoid valve of the hydraulic lift system control valve from the time the lift switch is operated to the lower side until the distance detection sensor detects that the aircraft has moved forward a predetermined distance. Since the plow is equipped with a control means for rapidly lowering the plow, it is possible to eliminate the troublesome operation of lowering and returning the manual lever at the edge of the furrow, which was conventionally required. Furthermore, compared to the conventional method in which a descending proportional solenoid valve is excited for a certain period of time using a timer, etc., in this invention, the distance from the furrow to the set plowing depth, that is, the plowing distance, is approximately constant. Therefore, there is no fear that the area near the headland will be disturbed or uneven, the plow can be easily operated even by an inexperienced person, and the plow can be easily lowered near the headland.

[Brief explanation of the drawing]

The figures show an embodiment of this invention, with FIG. 1 being a side view, FIG. 2 being a block diagram, and FIG. 3 being a flowchart. Explanation of symbols, 1...Tractor, 2...Front wheel,
3... Rear wheel, 12... Plow, 16... Draft sensor, 18... Distance detection sensor (wheel rotation sensor), 20... Draft setting means (draft lever), 22... Elevation switch, 24... Control Means (control device).

Claims (1)

[Scope of utility model registration request] A lift switch that raises and lowers the plow connected to the rear of the aircraft, a distance detection sensor that detects the forward distance of the aircraft, a draft setting means that sets the traction resistance applied to the plow, and a draft sensor that detects the traction resistance applied to the plow. The tractor is configured to maintain the plow at a set traction resistance value while comparing the set value set by the draft setting means and the detected value detected by the draft sensor, A predetermined current is passed through the lowering solenoid valve of the hydraulic lift system control valve from the time the switch is operated to the lowering side until the distance detection sensor detects that the aircraft has moved forward a predetermined distance. A hydraulic lifting control device for a tractor, characterized by being provided with a control means for rapidly lowering a plow.