JPH11275911A - Tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent engine stall and lowering of working accuracy followed by increase of tilling load in automatic control of tilling depth of a tractor. SOLUTION: Tilling depth target value of engine rotation obtained by adding increasing amount of a lift arm corresponding to the lowering content of number of engine rotation to a lift arm target value is set when tilling load is increased during automatic control of tilling depth and control for engine rotation and tilling depth lifting carrying out automatic lifting and lowering control of the lift arm is practiced according to the deviation of lift arm sensor value to engine rotation tilling depth target value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a tractor having an automatic tillage depth control function.

[0002]

2. Description of the Related Art Generally, in a tractor of this type, a tilling portion connected to a rear portion of an airframe via a lifting link mechanism is provided.
It is known to have a cultivation depth automatic control means that automatically raises and lowers with the cultivation depth setter as a target, but even if the cultivation unit maintains the set cultivation depth, the load on the cultivation unit is soil And so on, there is a possibility that inconvenience such as stalling may occur based on overload of the tilling part.

[0003]

In the prior art, however, the operator has judged the overload of the tilling section and manually raised the tilling section based on the judgment. In this case, however, the tilling section is required. There is a possibility that the work accuracy may be significantly reduced by raising the height as described above, or conversely, the engine stall may not be avoided due to a shortage of the tilling part.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made to solve these problems, and is provided with a tilling system connected to a traveling body via a lifting link mechanism. A tractor comprising a cultivation depth setting device for setting the cultivation depth of the cultivation portion, and a cultivation depth automatic control means for automatically raising and lowering the cultivation portion with the aim of the set cultivation depth of the cultivation depth setting device, The tilling depth automatic control means is provided with an overload determining means for determining an overload of the tilling part, and an overload avoiding means for automatically raising the tilling part by an amount corresponding to the overload. Things. In other words, when an overload occurs in the tilling part, the tilling part is automatically raised by an amount corresponding to the overload, so that it is not permissible to avoid inconveniences such as engine stall due to the overload. It is possible to minimize a decrease in work accuracy due to an increase in the number of parts. Further, a low-speed return means for lowering and returning the tillage portion raised in response to the overload at a low speed toward the set tillage depth position is provided. In other words, it is possible to avoid the inconvenience of falling into the overload state as much as possible, such as when the tilling section raised in response to overload is suddenly returned and lowered. There is no inconvenience that the automatic ascent is frequently repeated. As a result, it is not possible to stabilize the elevating operation of the tilling unit, and it is possible to improve the working accuracy.

[0005]

Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of a tractor, and a working machine (tiling unit) 3 such as a rotary is provided at a rear portion of the traveling body 1 via a lifting link mechanism 2.
Are connected so as to be able to move up and down freely. And the working machine 3
Moves up and down with the vertical swing of the lift arm 5 that suspends the lifting link mechanism 2 via the lift rod 4, while the expansion and contraction of the lift rod cylinder 6 interposed between the left and right lift rods 4 Accordingly, the basic structure is the same as that of the related art.

Reference numeral 7 denotes a lift cylinder for moving the lift arm 5 up and down. The lift cylinder 7 expands and contracts with the valve switching operation of the lift arm electromagnetic switching valve 8. Solenoid 8a for switching the solenoid 8 and the solenoid 8 for reduction
Since b can be driven based on the inching pulse, the operating speed of the lift cylinder 7 can be controlled based on the duty setting (ON time / cycle) of the inching pulse.

9 is a microcomputer (CPU, RO
M, RAM, etc.), and a lift arm sensor 10 for detecting the position of the lift arm 5 and a swing angle of the rear cover 3a are provided on the input side of the control unit 9. Rear cover sensor 11, which detects the tillage depth,
A position sensor 13 for detecting an operation position of a position lever (working machine-to-machine height setting device) 12, a lever position sensor 14 for detecting an operation position of an engine control lever (engine speed setting device) (not shown), Pitching sensor 15 for detecting the forward / backward inclination, engine rotation sensor 16 for detecting the engine speed changing according to the tillage load (in the present embodiment, an output signal of an alternator that generates AC power by engine rotation is used), Plowing depth automatic switch 17 for turning ON / OFF the control, plowing depth setting volume (work equipment-to-ground height setting device) 18 for setting the target plowing depth of the plowing depth automatic control, mode of the plowing depth automatic control (pitching control mode, rear cover) Control mode) is connected via an input interface circuit. Write to the output side, decompression and reduction solenoid 8a of the lifting arm solenoid switching valve 8,
8b and the like are connected via an output interface circuit.

That is, the control unit 9 sets an input data set for setting various input data to predetermined variables and a position data set for setting a position target value (lift arm target value) based on a position sensor value. ”,“ Plowing depth data set ”that sets the plowing depth target value (lift arm target value or rear cover target value) based on the plowing depth setting volume value, etc., and the lift arm according to the deviation of the lift arm sensor value from the position target value. Repeatedly execute subroutines such as "position output control" that outputs a lifting command, and "plow output control" that outputs a lift arm lifting command according to the deviation of the lift arm sensor value (or rear cover sensor value) from the target plowing depth value. In the following, the "till depth data set" Beauty be described with reference to a flowchart of control procedure of "tilling depth Output Control". As the mode of the plowing depth automatic control, a lift arm target value is set based on a plowing depth setting volume value and a pitching sensor value, and a lift arm lifting / lowering command is issued in accordance with a deviation of the lift arm sensor value from the lift arm target value. And a rear cover control mode in which a rear cover target value is set based on the plowing depth setting volume value and a lift arm elevating command is output in accordance with a deviation of the rear cover sensor value from the rear cover target value. ,
Manual mode switching according to the operation of the cultivation depth mode switching switch 19 or automatic mode switching based on a predetermined situation determination is executed. However, since the concept of the present invention in each mode is substantially the same, the rear cover control mode The flowchart (including mode switching) and detailed description thereof will be omitted.

In the "plowing depth data set", subroutines "pitching control target data set", "engine rotation reference data update" and "engine rotation plowing target data set" are sequentially executed. I have. In the “pitching control target data set”, a lift arm reference target value (see graph 1) is set based on the plowing depth setting volume value, and the lift arm reference target value is corrected based on the pitching sensor value (graph Then, the lift arm correction target value is set to the pitching target value.

In the "engine rotation reference data update", first, the state of an engine rotation reading permission flag set at the time of a position ascending operation is determined, and if the determination result is set, the engine rotation reading described later will be performed. Determine the state of the flag. If the determination result is a set, the current engine speed is set in the engine speed reference data, and then the engine speed read permission flag and the engine speed read flag are reset. That is, the engine rotation read flag is a flag that is set when the lift arm sensor value falls within the dead zone of the pitching target value and the engine rotation speed is maintained in a stable state for a predetermined time.
The engine rotation reference data is updated to an appropriate value each time the cultivation depth automatic control (pitching control) is restarted by lowering the. The processing for setting the engine rotation reading permission flag, the processing for setting the engine rotation reading flag, and the processing for switching between position control and automatic plowing depth control are not described in the flowchart.

On the other hand, when it is determined that the engine rotation reading permission flag is in the reset state, the operation of the engine control lever and the operation of the tillage depth setting volume are determined. When the engine control lever is operated, the engine rotation reference data is updated through the determination of the setting of the engine rotation reading flag. When the engine control lever is operated during the operation of raising and lowering, the current position of the engine position is read without reading the current engine speed.
4, the engine rotation reference data is corrected based on the detected value. That is, since the engine speed is unstable during the operation of the engine rotation depth control, the operation amount of the engine control lever is converted into a change amount of the engine speed, and the converted value is added to the engine rotation reference data (or Subtraction).

Also, when the tillage setting volume operation is performed, the engine rotation reference data is updated through the determination of the setting of the engine rotation reading flag. However, if the lift arm sensor value is larger than the pitching target value and the engine rotation When the tillage depth control is in operation, the current engine rotation reference data is held. That is, in the situation where the tillage depth setting volume 18 is operated in the depth direction and the engine rotation tillage depth control is operated accordingly, the current engine rotation reference data is held so as to avoid reading the unstable engine speed. It has become.

In the "engine rotation tillage depth target data set", a deviation of the current engine rotation data with respect to the engine rotation reference data (the amount of change in the engine rotation due to the fluctuation of the tillage load) is calculated, and the deviation is set in advance. It is determined whether or not the difference is larger than the lower limit data. If the determination is NO, the deviation is replaced (set) with predetermined data (for example, “0”). After the deviation is determined, the deviation is converted into a lift arm lift amount using a predetermined function (a function that specifies the lift arm lift amount required for returning the engine speed to the reference speed based on the deviation). At the same time, the conversion data is added to the lift arm storage data (or the pitching target value), and this data is set to the lift arm target value. Further, after setting the lift arm target value, it is determined whether or not the lift arm target value is larger than the pitching target value.
In the case of ES, the lift arm target value is set to the engine rotation depth setting value and the engine rotation depth control flag is set.

In the "tilling depth output control", first, it is determined whether or not the lift arm data (current lift arm sensor value) is smaller than a pitching target value. If the lift arm data is smaller than the pitching target value and is outside the dead zone, the lift arm 5 is raised at a speed corresponding to the deviation of the lift arm data from the pitching target value, while the lift arm data is If it is larger than the target value and deviates from the dead zone, the lift arm 5 is lowered at a speed corresponding to the deviation of the lift arm data from the pitch target value, and the lift arm data is included in the dead zone of the pitch target value. In this case, the lifting of the lift arm 5 is stopped, but when the lift arm 5 is lowered, it is determined beforehand whether or not the engine rotation depth control flag is in a reset state. If the determination is NO, the engine is replaced with the lift arm 5 Utateko adapted to perform a deep control.

In the engine rotation depth control, it is determined whether the lift arm data is smaller than the engine rotation depth target value, and the lift arm data is smaller than the engine rotation depth target value and the dead zone is determined. If it is out of the range, the lift arm 5 is raised at a speed corresponding to the deviation of the lift arm data with respect to the engine rotation till depth target value, while the lift arm data is larger than the engine rotation till depth target value and from the dead zone. If it is off, the lift arm 5 is lowered at a speed corresponding to the deviation of the lift arm data with respect to the engine rotation till depth target value. Further, when the lift arm data is included in the dead zone of the engine rotation till depth target value, Stops the lifting of the lift arm 5. As described above, the engine rotation tillage depth target value is a value obtained by adding the lift arm lift amount corresponding to the decrease in the engine rotation to the lift arm storage data, so that the engine rotation reduction with the increase in the tillage load is performed. The lift arm 5 is automatically raised so as to offset the pressure, and as a result, it is not possible to avoid inconvenience such as stalling due to an increase in the tillage load, and the work accompanying the rise of the work machine 3 is not allowed. The reduction in accuracy can be minimized.

When the engine speed rises with the automatic raising of the work implement 3 by the engine rotation depth control, the lift arm 5 is automatically lowered toward the pitching target value (lift arm storage data). However, since the descent command signal of the engine rotation plowing depth control is an intermittent drive signal with a low duty ratio, the lift arm 5 returns at a low speed toward the pitching target value. Therefore, it is possible to avoid such an inconvenience that the work machine 3 which has risen in accordance with the tillage load suddenly returns and descends and falls into an overload state again. As a result, the work machine 3 in accordance with the tillage load can be prevented. This can prevent the inconvenience that the automatic ascent of the work machine is frequently repeated, and furthermore, it is not possible to stabilize the elevating operation of the work machine 3 but also to improve the work accuracy. . The engine rotation depth control is automatically switched to pitching control when the lift arm data enters the dead zone of the pitching target value.

In the configuration described above, in the automatic plowing depth control state, a pitching target value as a target value of the lift arm 5 is set based on the plowing depth setting volume value and the pitching sensor value, and the pitching target value is set. Pitching control for automatically raising and lowering the lift arm 5 in accordance with the deviation of the lift arm sensor value with respect to, but when the tillage load of the work implement 3 increases,
An engine rotation plowing target value (lift arm target value) is set by adding the lift arm lift amount corresponding to the decrease in the engine speed to the lift arm storage data (or pitching target value), and the engine rotation plowing target value is set. Engine rotation tillage control for automatically controlling the lift arm 5 to move up and down according to the deviation of the lift arm sensor value with respect to. Accordingly, the working machine 3 automatically rises so as to offset the decrease in engine rotation due to the increase in the tilling load, and as a result, it is possible to avoid inconvenience such as engine stall due to the increase in the tilling load. In addition, it is possible to minimize a decrease in work accuracy due to the rise of the work machine 3.

In order to automatically return and lower the working machine 3 which has risen based on the engine rotation tillage control, the lifting arm 5 is lowered at a low speed, so that the working machine 3 which has risen according to the tillage load is suddenly moved. It is possible to avoid such an inconvenience as falling back into an overload state as in the case of returning down. Therefore, it is possible to prevent inconvenience that the working machine 3 automatically repeats ascent automatically according to the tillage load, and as a result, it is not possible to stabilize the lifting and lowering operation of the working machine 3 and improve the working accuracy. be able to.

The engine rotation reference data, which is used as a criterion for determining the tillage load, is updated when the lift arm sensor value falls within the dead zone of the pitching target value and the engine rotation speed remains stable for a predetermined time. Highly accurate tillage load determination can be performed based on appropriate engine rotation reference data.

When the engine control lever operation or the tillage setting volume operation is performed, the engine rotation reference data is updated. Therefore, the accuracy of the tillage load judgment based on the engine control lever operation and the tillage setting volume operation is reduced. It is possible to prevent the inconvenience of reduction.

Further, in updating the engine rotation reference data based on the operation of the engine control lever or the operation of the tillage depth setting volume, the engine rotation reference data is not updated during the engine rotation tillage depth control. The inconvenience of setting the correspondingly reduced engine speed in the engine speed reference data can be avoided.

Further, since the engine rotation tillage target value is calculated based on the lift arm data stored at the start of the control, the pitching target value changes during the engine rotation tillage depth control based on the tillage depth setting volume operation. Even if it does, a stable control state can be maintained.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a block diagram illustrating input and output of a control unit.

FIG. 3 is a flowchart showing a main routine.

FIG. 4 is a flowchart showing a “plowing depth data set”.

FIG. 5 is a flowchart illustrating a “pitching control target data set”;

FIG. 6 is a flowchart showing “engine rotation reference data update”.

FIG. 7 is a flowchart showing an “engine rotation depth target data set”;

FIG. 8 is a flowchart showing “tilling depth output control”.

FIG. 9 is a graph showing the elevating operation speed in each state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 3 Work machine 5 Lift arm 9 Control part 10 Lift arm sensor 16 Engine rotation sensor 18 Plowing depth setting volume

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Tamura 667 Iida-cho, Oji, Higashi-Izumo-cho, Yatsuka-gun, Shimane 1 Inside Mitsubishi Agricultural Machinery Co., Ltd. Address 1 Inside Mitsubishi Agricultural Machinery Co., Ltd.

Claims (2)

[Claims] 1. A tillage section connected to a traveling machine body via a lifting link mechanism, a tillage depth setting device for setting a tillage depth of the tillage portion, and a tillage portion with a target tillage depth set by the tillage depth setting device. In a tractor comprising automatic tillage depth control means for automatically raising and lowering the cultivation depth, the tillage depth automatic control means includes an overload determination means for determining an overload of the tilling part, and a tilling part by an amount corresponding to the overload. A tractor provided with overload avoidance means for automatically ascending. 2. The tractor according to claim 1, further comprising low-speed return means for returning the tilling portion raised in response to the overload at a low speed toward a set cultivation depth position.