JPH0616649B2 - Automatic control device for tractor tilling depth - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tilling depth automatic control device for controlling a working depth of a working machine such as a rotary tiller mounted on a tractor to a constant value. .

(B) Conventional Technology Conventionally, there is known a technology of automatically controlling the working depth of a rotary tiller equipped with a tractor to a constant value by pulse driving of a solenoid valve.

For example, JP-A-55-138303 and JP-A-55-55
It is as in Japanese Patent Publication No. 141103.

(C) Problems to be Solved by the Invention In a conventional electrically constructed plowing depth automatic control device, a technique for changing the duty ratio of pulse drive in accordance with the deviation between the plowing depth set value and the lift angle is as follows. It is known from the above two cited examples.

However, in this technique, the difference between the rising time and the falling time is configured to be absorbed by setting the magnitude of the pulse period. However, even with this, there is a high possibility that hunting will occur in the convergence of the control.

The present invention improves the above-mentioned conventional technique to change not only the pulse period in rising / falling but also the position of the deviation angle at which the duty ratio starts to decrease, so that the duty ratio decreases to the final matching position. The range is also different, and the rate of decrease is also "gradual" or "rapid".

This configuration eliminates control overshoot and speeds up convergence.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

In the automatic control device configured to switch the hydraulic switching valve operated by the solenoid valve to the working depth set value provided with the dead zone on the upper and lower sides and move the lift arm up and down to approach the working depth setting value. The operation is pulse drive, and the pulse cycle is made different between rising and falling,
The rising pulse cycle is set to be larger than the falling pulse cycle, and the duty ratio in the pulse cycle is gradually reduced to a small value at the beginning when the lift angle is close to the set value. However, as it approaches the dead zone, the rate of decrease increases, and when it enters the dead zone, it becomes 0 at once. As it goes down, the rate of decrease slows down to zero when the dead zone is reached.
It is what

(E) Configuration of Embodiments The objects and configurations of the present invention are as described above. Next, the configuration of the embodiments shown in the accompanying drawings will be described.

FIG. 1 is a side view showing an automatic cultivating depth control device for a tractor of the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is a plan view of an operation box 11 part.

The configuration will be described with reference to FIGS. 1, 2, and 3.

A hydraulic case N is arranged on the tractor mission case M. Left and right lower links 14, 14 project from the rear end side surface of the mission case M so as to be vertically rotatable. Further, the top link hinge 21 projects from the rear surface of the hydraulic case N, and the top link 15 is pivotally supported at the rear end of the top link hinge 21.

The two lower links 14, 14 and one top link 1
5, the rotary tiller R is attached so as to be vertically rotatable. Bevel gearbox 2 of rotary tiller R
Power is transmitted from the PTO shaft 23 of the mission case M to the No. 2 via the universal joint shaft.

The rotary tiller R is configured to till the soil by rotating the tiller 7 and to level the tilled soil by the rear cover 1.

In the present invention, the rear cover 1 is also used as a sensor for detecting the working depth, and the vertical rotation state of the rear cover 1 is arranged on the side of the hydraulic case N via the sensor wire 12. Input to the depth sensor 5.

The depth sensor 5 is composed of a potentiometer in this embodiment.

A hydraulic cylinder and a piston are arranged inside the hydraulic case N, and lift arms 8 that are vertically rotated by the device are projected rearward. Lift links 13, 13 are pivotally connected to the rear ends of the lift arms 8, 8, and the lower ends of the lift links 13, 13 are connected to the lower links 14, 13.
It is connected to the middle of 14.

A lift angle sensor 4 for detecting a rotation angle of the lift arm 8 is arranged at a rotation base of the lift arm 8.

A seat 24 is arranged above the hydraulic case N, and a position lever 2 for the operator to manually set the height of the rotary tiller R is arranged beside the seat 24.

A position setter 6 for detecting a set value by the position lever 2 is arranged at the rotation base of the position lever 2.

A control 16 is arranged between the seat 24 and the hydraulic case N, and a microcomputer as a control device, an A / D converter and the like are arranged in the controller 16.

Further, the solenoid valve 3 is provided inside or on the side of the hydraulic case N.
Hydraulic switching valve 17 using 0 and 31 as pilot valves
Are arranged. The output signal after the control judgment by the controller 16 is transmitted to the solenoid valves 30 and 31 of the hydraulic pressure switching valve 17 and fed back.

Further, a traveling speed change lever 3 for operating a forward / reverse speed change device arranged inside the mission case M is rotatably arranged for a speed change operation, and at the base of the traveling speed change lever 3,
A backs switch 19 is arranged to detect a state in which the traveling speed change lever 3 is changed to a reverse position.

Further, an operation box 11 for automatic control of the working depth is fixedly provided on the lower surface of the rear portion of the dashboard 25. A plowing depth setting dial 9 and a lift switch 10 are arranged on the upper surface of the operation box 11.

The plowing depth setting dial 9, the lift angle sensor 4, the depth sensor 5, and the position setting device 6 are all constituted by potentiometers whose voltage values change by rotating.

Further, the lift switch 10 is constituted by a switch which is turned on only when the operator operates the raising side or the releasing side, and is turned off when the hand is released.

Further, there is provided an automatic switch 28 which is turned on when the tilling depth setting dial 9 is fully rotated in the deepening direction. When the plowing depth setting dial 9 is rotated and is in a place other than "OFF", the automatic OFF switch 28 is OFF, which means "auto mode". Then, when the working depth setting dial 9 is rotated to the "OFF" position, the automatic OFF switch 28 is turned ON, and the "position mode" is set in reverse.

FIG. 4 is a schematic drawing of the controller 16.

In the controller 16, a microcomputer, A
A / D converter, an input element and the like are arranged, and signals of the engine start key 26, the working depth setting dial 9, the depth sensor 5, the lift angle sensor 4, the position setter 6, the lift switch 10, etc. are input.

The output signal is a signal that operates the solenoid valves 30 and 31.

FIG. 5 is a hydraulic circuit diagram of the automatic plowing depth control system of the present invention.

The hydraulic pressure switching valve 17 uses solenoid valves 30 and 31 as pilot valves. Solenoid valve 30
Is for lowering, and the lowering main valve 37 is operating. The solenoid valve 31 is raised and the raising main valve 38 is operated.

29 is a hydraulic pump attached to the engine of the tractor,
32 is a relief valve, 33 is a stop valve, 34 is a slow return valve, 36 is a safety valve, 35
Is a hydraulic lift cylinder in the hydraulic case N.

(F) Operation Next, the operation of the automatic working depth control system of the present embodiment will be described with reference to FIGS. 6 to 9.

FIG. 6 is a data table that defines changes in duty ratio with respect to changes in set value and lift angle, FIG. 7 is a drawing showing a control operation routine in “position mode”, and FIG. 8 is a control operation routine in “auto mode”. Showing the ninth
The drawing is a drawing showing a control operation routine in the "lift-up mode".

An outline of the control action of the present invention will be described.

The essential part of the present invention operates the hydraulic switching valve 17 when the value of the lift angle sensor 4 deviates from the set plowing depth value set by the position setter 6 or the plowing depth setting dial 9. Then, the lift arm 8 is moved up and down to act to match the set value, but the solenoid valve 30 for moving the lift arm 8 to the matching point,
The operation state of 31 is set.

As shown in FIGS. 7, 8, and 9, in each mode, the deviation between the set value and the lift angle sensor 4 is calculated, and the deviation is determined by the data table in FIG. The duty ratio is extracted, the solenoid valves 30 and 31 are excited with the duty ratio, and the lift angle sensor 4 is made to match the set value.

As shown in the data table disclosed in FIG. 6, the pulse cycle is set to 48 mm seconds on the rising side, and conversely, the pulse cycle at the time of falling is set to 24 mm seconds. By providing this difference, the solenoid valve 30 is frequently operated at the time of descending to control the return amount of the hydraulic oil, so that a converged state without overshoot can be obtained.

Further, the basic control is to make the set value and the value of the lift angle sensor 4 coincide with each other. However, in practice, unless a slight dead zone is set between the set value and the lift angle sensor 4 value, the value will be around the set value. The control causes a hunting state, resulting in an unstable control state.

In this embodiment, the dead zone is set to 1.5 degrees when approaching the set value from the ascending state, and is set to 1.5 degrees when approaching the set value from the descending state, for a total of 3.0 degrees. This makes the control stable. The maximum lift angle deviation is set to 75 degrees.

In the case of the "lift-up mode" of FIG. 9, the set values are the maximum value of the lift arm 8 and the set values of the "position mode" and "auto mode" before operating the lift switch 10.

"SD" is a self-diagnosis flowchart.

The essential part of the present invention lies in the set values in the data table of FIG.

That is, when the working machine is raised, it is pushed up only by the hydraulic pressure, so that it can be directly controlled by the operation of the solenoid valve 31, and the change of the duty ratio directly changes the rising speed. This makes it possible to obtain a converged state in which no overshoot that exceeds the set value occurs.

That is, the duty ratio begins to decrease for the first time when the lift angle deviation is about 12 °, and it gradually decreases at first.
The duty ratio is reduced at a faster rate as it approaches the dead zone. Even so, the duty ratio before the final matching state is reduced to only about 70%, and the duty ratio is set to 0 at once at the time of entering the dead zone.

As seen from the data table of FIG. 6, the shape of the data table curve on the left side on the ascending side is convex upward.

However, when the work machine descends, the work machine descends due to the weight of the work machine. Therefore, the acceleration of gravity is added, and the solenoid valve 3
Therefore, a descending state different from the operation of 0 occurs. That is, in order to stop the descending state with acceleration, it is necessary to close the descending main valve early from the position separated from the set value, and also rapidly reduce the duty ratio.

That is, in the data table on the left side of the data table of FIG. 6, the lift angle deviation before the matching position is 2
From around 4 °, the duty ratio begins to decrease in order to shorten the time for closing the lowering main valve 37, and the duty ratio also decreases rapidly until the deviation angle is about 18 °. And as we approach the dead zone,
The decreasing speed becomes gradually, and before the stop, the duty ratio is already lowered to about 40% to create a state almost close to the stop, and finally it is set to 0, and the lowering main valve 37 is closed.

The data table in the lowered state is a concave data table drawn on the upper side, as shown in the right part of FIG.

By configuring the data table as described above, the first
As shown by U and D in the drawing, the changes in the ascending speed and the descending speed can be made substantially the same.

(G) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

First, since the acceleration of gravity is not applied when the working machine is raised, the amount of pressure oil from the hydraulic pressure switching valve 17 becomes the speed of the working machine as it is, and the duty ratio may be reduced at once just before entering the dead zone. In the case of lowering, the acceleration of gravity acts, and therefore the hydraulic pressure switching valve 17 is closed and the overshoot still occurs.

Therefore, at the time of descending, the lift angle rapidly and drastically decreases from the position separated from the set value from the beginning, the decreasing speed slows as it approaches the dead zone, and becomes completely 0 when it enters the dead zone. It was possible to prevent the state of overshoot caused by the acceleration of gravity.

Secondly, in the case of ascending, the lift angle gradually and gradually decreases from the position close to the set value at the time of ascending, and the decreasing speed increases as the dead zone is approached. Therefore, by controlling in consideration that the acceleration of gravity is not added, the overshoot could be prevented even in this case.

[Brief description of drawings]

FIG. 1 is a side view showing an automatic cultivating depth control device for a tractor of the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a plan view of an operation box 11 part, FIG. 4 is a schematic view of a controller 16, and FIG. FIG. 5 is a hydraulic circuit diagram of the automatic plowing depth control device of the present invention,
FIG. 6 is a data table that defines changes in duty ratio with respect to changes in set value and lift angle, FIG. 7 is a drawing showing a control operation routine in “position mode”, and FIG. 8 is a control operation routine in “auto mode”. Showing the ninth
The drawing is a drawing showing a control operation routine in the "lift-up mode". 1 ... Rear cover 2 ... Position lever 3 ... Travel speed change lever 4 ... Lift angle sensor 5 ... Depth sensor 6 ... Position setting device 7 ... Tilling pawl 8 ... Lift arm 9 ... Tillage depth setting dial 10 ...... Lift switch 17 ...... Hydraulic switching valve 19 ...... Back switch 30 ...... Descent solenoid valve 31 ...... Rise solenoid valve

Claims (1)

[Claims] 1. An automatic control device configured to switch a hydraulic switching valve operated by a solenoid valve to a plowing depth set value having upper and lower dead zones and move a lift arm up and down to approach the plowing depth set value. In the above, the operation of the solenoid valve is pulse-driven, the pulse period is made different between rising and falling, the rising pulse period is made larger than the falling pulse period, and the duty ratio in the pulse period is , At the time of rising, from the position where the lift angle is close to the set value, at first, it gradually decreases gradually and gradually, the speed of decrease is accelerated as it approaches the dead zone, and when it enters the dead zone, it becomes 0 at once and on the contrary, at the time of descending , The lift angle rapidly and drastically decreases from the position separated from the set value from the beginning, and the decreasing speed slows down as it approaches the dead zone, and becomes completely 0 when it enters the dead zone. Tilling depth automatic control system for a tractor, characterized and.