JPS62190014A - Plowing depth automatic controller of tractor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an automatic tillage depth control device for controlling the tillage depth of a working machine such as a rotary tiller mounted on a tractor to a constant value.

(b) Prior Art Techniques for automatically controlling the plowing depth of a rotary tiller mounted on a tractor to a constant value by pulse driving a solenoid valve have been known.

For example, Japanese Patent Publication No. 55-138303 and Japanese Patent Publication No. 55-1983
This is as in Publication No. 141103.

In the conventional electric plowing depth automatic control device, the technique of changing the pulse drive duty ratio in response to the deviation between the plowing depth set value and the lift angle is known from the above two cited examples. It is.

(c) Problems to be solved by the invention The purpose of the invention is to solve the problems as shown in the drawings of FIGS.
The feedback value of the depth sensor 5 constituted by the rear cover 1 may be different even for the same plowing depth, and this may result in control uncertainty, so this problem is solved.

In other words, when using the rear cover 1 or the equivalent which is attached to the rear of the tilling cover and can freely rotate up and down, the rear cover etc. does not move up and down in parallel, but rotates up and down. , the rotation angle a when the rear cover 1 moves up and down by the tilling depth t when the plowing depth is deep as shown in Fig. 4, and the rotation when the rear cover 1 moves up and down by the same plowing depth t when the plowing depth is shallow as shown in Fig. 5. It is different from a corner.

Therefore, since the rotation width of the rear cover is determined as a feed hack value by the depth sensor 5 constituted by a potentiometer, the range of change in the acid value is different.

Therefore, due to the difference in the rotation angle a-b, if the width of the dead zone provided above and below the set value is not changed, when the plowing depth is shallow as shown in FIG. The rotation immediately jumps out of the dead zone, causing the hydraulic switching valve 17 to switch, causing a hunting condition and making the control unstable.

In order to improve this point, the present invention increases the dead zone width Z when the working machine is located above, that is, when the plowing depth is shallow, and when the working machine is located below, that is, when the plowing depth is deep. , the dead zone width Z is made smaller.

(d) Means for Solving the Problems The objects of the present invention are as described above. Next, the structure for achieving the objects will be explained.

In a configuration in which the lift arm 8 is moved up and down depending on the deviation between the set value of the tilling depth setting dial 9 and the value of the depth sensor 5, the value of the depth sensor 5 and the set value of the tilling depth setting dial 9 are made to match. A dead zone is provided above and below the set value of 9, and the width of the dead zone is corrected and changed based on the value of the lift angle sensor 4.

(E) Structure of the Embodiment The object and structure of the present invention are as described above. Next, the structure of the embodiment shown in the attached drawings will be explained.

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

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

A hydraulic case N is placed on top of a transmission case M of a tractor. Left and right lower links 14 protrude from the rear end side of the mission case M so as to be movable up and down. Further, a top link hinge 21 protrudes from the rear surface of the hydraulic case N, and a top link 15 is pivotally supported at the rear end of the top link hinge 21. The two lower links 14 and one top link 15 allow the rotary tiller R to be mounted so as to be vertically movable. Power is transmitted from a PTO shaft 23 of a bevel gear box 22 of a rotary tilling system gR to a hemi- sion case M via a universal joint shaft.

The rotary tilling device R is configured to till the soil by rotating the tilling claws 7 and to level the tilled soil using the rear cover 1.

In the present invention, the rear cover 1 is also used as a sensor for detecting the plowing depth, and the vertical rotation state of the rear cover 1 is detected through a sensor wire 12 arranged on the side of the hydraulic case N. It is input to a depth sensor 5. In this embodiment, the depth sensor 5 is constituted by a potentiometer.

Further, a hydraulic cylinder and a piston are arranged inside the hydraulic case N, and lift arms 8, 8, which are moved up and down by the device, protrude 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,
It is pivoted in the middle of 14.

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

Further, a seat 24 is arranged above the hydraulic case N, and on the side of the seat 24 there is a position lever 2 for the operator to manually set the height of the rotary tiller R.
is located.

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

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

Further, a hydraulic switching valve 17 using a solenoid valve as a pilot valve is disposed inside or on the side of the hydraulic case N. The output signal after the control decision by the controller 16 is sent to the solenoid valve of the hydraulic switching valve 17 and is fed-banked.

Further, a travel gear shift lever 3 for operating a forward/reverse transmission disposed inside the mission case M is rotatably arranged for speed change operation, and at the base of the travel gear shift lever 3,
A back switch 19 is arranged to detect the state in which the traveling speed change lever 3 is shifted to the reverse position.

Further, an operation box for automatic reverse control is fixedly installed on the lower surface of the rear part of the dash board 25. A plowing depth setting dial 9 and a lift switch 10 are arranged on the top surface of the operation box 11.

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

In addition, the lift switch 10 is turned ON only when the operator operates it to the upward or downward direction, and turns ON when the operator releases it.
It is composed of switches serving as FF.

Further, auto-off switches 2 and 8 are arranged, which are turned on when the plowing depth setting dial 9 is fully rotated in the direction of increasing depth. When the plowing depth setting dial 9 is rotated to a position other than "off", the auto-off switch 28 is OFF and in an automatic control state.

(F) Function of the Embodiment Next, the function of the automatic tillage depth control device of the present embodiment will be explained with reference to the drawings of FIGS. 4 to 8.

Fig. 4 is a side view showing the rotational state of the rear cover 1 when the plowing depth is deep, Fig. 5 is a side view showing the rotational state of the rear cover 1 when the plowing depth is shallow, and Fig. 6 is a set price and lift. FIG. 7 is a diagram showing the correction of the dead zone width with respect to the lift angle, and FIG. 8 is a diagram showing the control operation routine of the "auto mode".

An overview of the control action of the present invention will be explained.

As shown in the data table disclosed in FIG. 6, the pulse period is set to 48 Km seconds on the rising side, and conversely, the pulse period on the falling side is set to 24 M seconds. By providing this difference, a convergence state without overshoot can be obtained by frequently operating the solenoid valve during descent and controlling the return amount of hydraulic oil.

In addition, the setting value of the plowing depth setting dial 9 and the depth sensor 5
The basics of control is to match the values of , but in reality, unless a slight dead zone is set between the set value and the 5 values of the depth sensor, the control will enter a hunting state near the set value, resulting in failure. This results in a stable control state. The present invention corrects the dead zone width Z by changing it based on the value of the lift angle sensor 4.

rS-DJ is a self-diagnosis flowchart.

As shown in the setting values of the data table in FIG. 6, the duty ratio, which is the ratio of the time during which the solenoid valve is turned on in each pulse, is changed as well as the pulse period.

Changing the duty ratio when the lift arm 8 is raised and lowered can be directly controlled by the operation of the solenoid valve 31, since when the work equipment is raised, it is pushed up only by hydraulic pressure. , the change in the duty ratio directly becomes a change in the rising speed. This makes it possible to obtain a convergence state in which overshoot that exceeds the set value does not occur.

In other words, the duty ratio begins to decrease when the lift angle deviation is around 12 degrees, and it is gradually reduced at first.
The duty ratio decreases faster as it approaches the dead zone. Even so, the duty ratio before the final matching state is reduced only to about 70, and when the dead zone width Z is entered, the duty ratio is suddenly reduced to 0.

Looking at the data table in FIG. 6, the shape of the data table curve on the rising side on the left is upwardly convex.

However, when the work equipment is lowered, it is lowered by the weight of the work equipment, so the acceleration of gravity is added, resulting in a lowering state that is different from the operation of the solenoid valve. In other words, in order to stop the descending state with acceleration, it is necessary to close the hydraulic switching valve 17 quickly from the position away from the set value, while rapidly reducing the duty ratio. .

In other words, in the data table of Fig. 6, the data table on the left descending side first shows that the lift angle deviation before the matching position is 2.
Already from around 4 degrees, the duty ratio begins to decrease in order to shorten the time during which the hydraulic switching valve 17 is closed, and the decrease in the duty ratio is rapidly reduced until the deviation angle reaches about 18 degrees.

As it approaches the dead zone, the speed of decrease becomes gradual, and before it stops, the duty ratio is already reduced to about 40, creating a state that is almost at a standstill, and finally it enters the dead zone width Z and completely closes the hydraulic switching valve 17. It is.

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

The data table for changing the duty ratio according to the lift angle deviation is moved parallel to the left and right in response to the change in the width of the central dead zone Z in the "auto mode" as described above. . In the case of the "position mode", the value of the dead zone width Z is configured to be constant.

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

Next, the present invention will be explained in detail.

The main part of the present invention is that when the value of the depth sensor 5 deviates from the set plowing depth value set by the plowing depth setting dial 9 and there is a deviation, the hydraulic switching valve 17 is operated and the lift arm 8 is activated. It moves up and down to match the set value, and when the lift arm 8 is moved to the point of failure, when it finally approaches the set value, it matches the set value at one point. Instead, it is configured such that a width of a dead zone is provided at the top and bottom, and the control is stopped when the width of the dead zone is within the width of the dead zone.

Conventionally, in the entire rotatable range of the lift arm 8,
Although the width of the dead zone was the same, as shown in Figs. 4 and 5, the rotation angle of the rear cover 1 for the same plowing depth a changes depending on whether the plowing depth is deep or shallow. Since the range of change in the value of the depth sensor 5 differs depending on the rotation angle, the dead zone width Z becomes inappropriate. That is, as shown in FIG. 4, when the change value of the depth sensor 5 is small, the dead zone width Z may be smaller; conversely, as shown in FIG. , it is necessary to increase the dead zone width Z. This change value is illustrated in Figure 7. While the lift angle of the lift arm 8 changes from approximately 0 degrees to 75 degrees, the dead zone width The Z angle is varied from 0 degrees to 13.5 degrees.

Since the dead zone width Z has the same width above and below the setting value of the plowing depth setting dial 9, the dead zone width Z is Z/2 when approaching from below when ascending, and the dead zone width Z when approaching from above when descending. The dead zone width Z is obtained by adding /2.

As described above, the reason why the dead zone width Z is changed by the lift angle of the lift arm 8 is that the rotation of the rear cover 10 is fed back by the depth sensor 5 to match the setting value of the tillage depth setting dial 9 during automatic tilling depth control. "auto mode"
However, in the case of "position mode" which is a control that matches the lift angle sensor 4 of the lift arm 8 with the value of the position setting device 6 set by rotating the position lever 2, hunting problems may occur. Since this does not occur, the dead zone width Z is fixed at 3.0 degrees.

Further, the "auto mode" control is performed according to the routine shown in FIG.

First, the deviation between the set value Correct the movement of the table by the amount that widens the dead zone width Z to the left and right, calculates the duty ratio for each deviation based on the corrected value, and sets the solenoid valve ONL so that the value of the depth sensor 5 is equal to the setting value of the tilling depth setting dial 9. The lift arm 8 is moved up and down so that it is within the upper and lower dead zone width Z.

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

The feedback value of the depth sensor 5 configured by the rear cover 1 may differ even for the same plowing depth, and this may result in control uncertainty. It is an invention.

That is, since the rear cover 1, which is attached to the rear of the tillage cover and can be rotated up and down, does not move up and down in parallel but rotates up and down, when the tillage depth is deep as shown in Fig. 4, the tillage depth is only t. The rotation angle a when the rear cover 1 moves up and down, and the fifth
As shown in the figure, when the plowing depth is shallow, the rotation angle is different from when the plowing depth is raised and lowered by the same plowing depth t.

In order to obtain the same plowing depth t, even with a rotation angle of 8,
The rotation angle of the rotary tillage device differs depending on its vertical position.

If the width of the dead zone provided above and below the set value is not changed due to the difference in the rotation angle a-b, the slight rotation of the lift arm 8 will immediately jump out of the dead zone and the hydraulic switching valve 17 This causes a hunting condition to occur, making control unstable.

In the present invention, by changing and correcting the dead zone width Z according to the lift angle, the rotation angle of the rear cover 1 is corrected for changing depending on the shallowness of the plowing depth.

This made it possible to obtain stable control convergence.

[Brief explanation of drawings]

Fig. 1 is a side view showing the automatic plowing 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 the operation box 11, and Fig. 4 is a rear cover when the plowing depth is deep. Fig. 5 is a side view showing the rotational state of rear cover 1 when the plowing depth is shallow, Fig. 6 is a side view showing the rotational state of rear cover 1 when the plowing depth is shallow, and Fig. 6 defines the change in duty ratio with respect to the deviation between the set value and the lift angle. The data table, FIG. 7 is a drawing showing correction of the dead zone width with respect to the lift angle, and FIG. 8 is a drawing showing the control operation routine of "auto mode". Z...Dead band width l...Rear cover 2...Position lever 3...Traveling gear shift lever 4...Lift angle sensor 5...Rear cover sensor 6...Position setter 7...Tilling claw 8... Lift arm 9... Depth setting dial 10... Lift switch 19... Hack switch Applicant Yanmar Diesel Co., Ltd. Agent Patent attorney Toshibe Yano Figure 7 ↑ T-D communication (n~, 1) 7) To β (&)
Greasy & -1 Pass.

Claims (1)

[Claims] In a configuration in which the lift arm 8 is moved up and down depending on the deviation between the set value of the tilling depth setting dial 9 and the value of the depth sensor 5, and the value of the depth sensor 5 and the set value of the tilling depth setting dial 9 match, the tilling depth setting dial 9. An automatic tillage depth control device for a tractor, characterized in that a dead zone is provided above and below a set value of 9, and the width of the dead zone is corrected and changed based on the value of a lift angle sensor 4.