JP2789243B2 - Tillage depth control device for agricultural tractors - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for controlling the plowing depth of an agricultural tractor.

(Prior Art) In the conventional device shown in FIGS. 5 to 7, a body 1 and a rotary claw 2 are connected by a swing arm 3. The swing arm 3 is connected to a control cylinder 5 via a lift arm 4.
Is linked to

When the control cylinder 5 is extended, the lift arm 4 rotates to the right in the drawing and raises the rotary pawl 2. When the control system 5 is contracted, the lift arm 4 rotates leftward in the drawing to lower the rotary pawl 2.

By controlling the height position of the rotary claw 2 in this manner, the amount of tillage can be controlled. That is,
If the height of the rotary claws 2 is relatively low, the plows are deeply plowed, respectively, and if the height is relatively high, the plows are shallowly plowed.

An electromagnetic hold valve 6 is provided on the bottom side of the control cylinder 5.
The electromagnetic valve mechanism V is connected via the.

The electromagnetic hold valve 6 keeps the illustrated normal position by the action of the spring 6a unless an exciting current is supplied. At this normal position, a hold state for preventing outflow of hydraulic oil from the control cylinder 5 is maintained. Then, by energizing the solenoid 6b, the open state which is the right side position in the drawing is maintained.

Further, the electromagnetic valve mechanism V includes a pressure compensating valve 7, a solenoid valve 8, and a control valve 9. The solenoid valve 8 shuts off the flow of hydraulic oil from the pump P at the normal position shown in the figure, but permits the flow of the hydraulic oil when the solenoid 8a is excited. The control valve 9 keeps the open state at the normal position, but when the solenoid 9a is excited, the opening degree is determined according to the exciting current.

Thus, when the solenoid 8a of the solenoid valve 8 is excited to switch it to the open position and the control valve 9 is kept in the illustrated closed position, the pressure oil from the pump P is released from the pressure compensating valve 7 →
It is supplied to the control cylinder 5 via the solenoid valve 8 → the electromagnetic hold valve 6. When the pressure oil is supplied to the control cylinder 5 in this manner, it is extended and raises the rotary pawl 2.

When the solenoid 9a of the control valve 9 is excited from the above state and opened, the hydraulic oil of the control cylinder 5 is returned to the tank T via the control valve 9. The contraction speed of the control cylinder 5 at this time is determined according to the opening of the control valve 9.

Eventually, the control valve 9 is excited or its excitation state is released, so that the control cylinder 5 is expanded and contracted to control the plowing depth.

The control mechanism for controlling the electromagnetic valve mechanism V is the circuit shown in FIG. This control circuit connects a comparison unit 11 to the control unit 10, and the comparison unit 11 receives an output signal from the position detection unit 12 and an output signal from the calculation unit 13.

The position detector 12 detects the actual position of the rotary claw 2 based on a signal from the lift arm sensor 14 and transmits the detection signal to the comparator 11.

Further, a target position setting unit 14 and a dead zone setting unit 15 are connected to the input side of the calculation unit 13.

The target position setting unit 14 sets a target height position of the rotary claw 2 and determines a plowing depth.

The dead zone setting section 15 is provided for the following reason.
That is, if the cultivated land is flat, maintaining the height position of the rotary claw 2 fixedly is an absolute condition for keeping the cultivated depth uniform. However, when the height position of the rotary claw 2 is fixed when the unevenness of the cultivated land is severe, the rotary claw 2 follows the pitching of the vehicle body 1 sensitively,
The cultivation depth also becomes uneven. Therefore, a dead zone is provided for the target position determined by the target position setting unit 14 so that the rotary claw 2 does not sensitively follow pitching of the vehicle body 1 or the like.

Both signals from the target position setting unit 14 and the dead zone setting unit 15 are input to the arithmetic unit 13. The calculating unit 13 calculates a specific target position and a dead zone based on both signals, and inputs the calculated values to the comparing unit 11.

Further, since the position signal from the position detection unit 12 is input to the comparison unit 11, the actual position of the rotary claw 2 is compared with the target position specified by the calculation unit 13 and the position in the dead zone. Is detected. The detection signal is input to the control unit 10, and the control unit 10 controls the electromagnetic valve mechanism V and the electromagnetic hold valve 6 according to the signal.

Then, the solenoid 6b of the electromagnetic hold valve 6 is energized to keep the hold valve 6 in the open position, which is the right position in the drawing.

In this state, for example, the actual position of the rotary claw 2 is
If the position is lower than the target position, the comparing unit 11 outputs a signal to that effect and transmits it to the control unit 10. Upon receiving this signal, the control section 10 outputs a signal for exciting the solenoid 9a of the control valve 9, and keeps the control valve 9 in the closed position shown in the figure. When the control valve 9 is kept at the closed position, the pressure oil from the pump P is supplied to the control cylinder 5. Therefore, the control cylinder 5 is extended, and the lift arm 4 is rotated clockwise to raise the height position of the rotary claw 2.

The position of the rotary claw 2 at this time is determined by a lift arm sensor.
When the rotary claw 2 reaches the target position, the control unit 10 operates and the solenoid of the control valve 9 is detected.
Blocks current to 9a.

When the energization of the solenoid 9a is stopped in this way, the control valve 9 keeps the open position, and the oil discharged from the pump P is returned to the tank T via the control valve 9.

At this time, since the weight of the rotary pawl 2 acts on the control cylinder 5, the hydraulic oil of the hydraulic cylinder 5 is returned to the tank T via the control valve 9. As a result, the rotary claw 2 descends by its own weight, but if it falls within the dead zone, the control valve 9 is not switched.

However, when the rotary claw 2 descends beyond the dead zone,
This is detected by the comparison unit 11 and the control unit 10 is operated to energize the solenoid 9a of the control valve 9 again. Therefore, the control valve 9 is switched to the closed position, and the discharge oil of the pump P is supplied to the control cylinder 5 to extend the cylinder 5. When the control cylinder 5 is extended, the position of the rotary pawl 2 rises and returns it to the range of the dead zone again.
FIG. 7 shows this situation.

(Problems to be Solved by the Invention) In the conventional device as described above, every time the rotary claw 2 located in the dead zone deviates from the dead zone,
The control valve 9 is excited to extend the control cylinder 5, and the rotary claw 2 is returned to the dead zone.

However, when the deviation from the dead zone and the return to the dead zone are repeated as described above, a phenomenon similar to a so-called hunting occurs, and there is a problem that the vehicle body 1 becomes unstable.

An object of the present invention is to provide a device that prevents a tilling member such as a rotary claw from deviating from a dead zone when the position is within a dead zone.

(Means for Solving the Problems) The present invention relates to a tilling member such as a rotary claw connected to a vehicle body, a hydraulic cylinder for controlling a height position of the tilling member, and a height of the tilling member by locking the control cylinder. It is premised on an agricultural tractor tillage depth control device equipped with an electromagnetic hold valve for maintaining the position and an electromagnetic valve control mechanism for supplying pressure oil to the control cylinder or returning the pressure oil to the tank. It is to be.

Then, while assuming the above-described tillage depth control device, the present invention provides a target position setting unit that sets the height position of the tillage member, and a first dead zone that sets a dead zone with respect to the target position set by the target setting unit. A setting unit, a position detecting unit that detects an actual position of the tilling unit, and a comparing unit that compares whether the actual position of the tilling member detected by the position detecting unit is within the range of the first dead zone width. A second dead zone setting unit for setting a dead zone to a width larger than the first dead zone width, and a delay timer that operates when the tilling member deviates from the second dead zone width. Second
It is characterized in that the electromagnetic hold valve is closed after a certain time counted by the delay timer from being located in the dead zone, and the tilling member is held in position.

(Operation of the Present Invention) Since the present invention is configured as described above, the electromagnetic hold valve closes after a certain period of time counted by the delay timer has elapsed since the tilling member entered the second dead zone. When the electromagnetic hold valve is closed in this way, the control cylinder is held at the position, so that it does not deviate from the dead zone.

(Effect of the present invention) As described above, while the position of the tilling member is stopped in the second dead zone, the solenoid hold valve closes to hold the position of the control cylinder. Do not deviate from

Therefore, the operation for correcting the deviation is eliminated, and the hunting phenomenon of the tilling member can be prevented accordingly.

(Embodiment of the Present Invention) In the embodiment shown in FIGS. 1 to 4, the structure of the vehicle body 1 and the provision of the electromagnetic hold valve 6 and the electromagnetic valve mechanism V are the same as those of the conventional art.

Therefore, the following description of the embodiment focuses on the control system, and the same components as those of the related art are denoted by the same reference numerals.

In the control circuit shown in FIG.
1. The position detecting unit 12, the calculating unit 13, the target position setting unit 14, and the first dead zone establishing unit 15 are completely the same as the conventional one.

The greatest feature of this embodiment is that a second dead zone setting unit 17 and a delay timer 18 are connected to the control unit 10.

As shown in FIG. 4, the second dead zone setting section 17 is larger than the width of the first dead zone. The reason why the width of the first dead zone is smaller than the width of the second dead zone is to accurately control the position of the rotary claw 2 during the tilling operation.
On the other hand, the reason why the width of the second dead zone is increased is to maintain a stable life when the work is stopped. If the second dead zone is made as narrow as the first dead zone, the following inconvenience occurs. For example, if the rotary claw 2 stops at the lower limit position of the first dead zone when the work is stopped, the rotary claw 2 will deviate from the dead zone if the rotary claw 2 slightly drops from the stop position. If you deviate from the dead zone, a raising signal that tries to correct it will be output,
In between, raising and lowering are repeated. Therefore, the first
A difference is made between the dead zone width and the second dead zone width. After the operation is stopped, control can be performed in the range of the second dead zone so that the raising and lowering of the rotary claw 2 is not repeated.

In addition, the delay timer 18 determines that the position of the rotary claw 2 is
The counting is started from the time when the first dead zone is moved to the second dead zone. Then, the control unit 10 starts counting by the delay timer 18, and after a lapse of a predetermined time,
The electromagnetic hold valve 6 is switched to a hold position.

 Next, the operation of this embodiment will be described.

As is clear from the flowchart of FIG. 2, first, the target position of the rotary claw 2, that is, the set position of the lift arm 4 is input in the I-th step, and the actual position of the lift arm 4 is input in the II-th step. I do.

In the third step, it is determined whether or not the tilling operation is being performed. If the tilling operation is being performed, the process proceeds to the fourth step. In this IV step, it is determined whether the rotary pawl 2, that is, the lift arm 4 is in the first dead zone, and the first
If it is in the dead zone, the process proceeds to the V-th step and the energization of the electromagnetic valve mechanism V is stopped. Then, in the VIth step, the delay timer 18 is operated to start counting, and the electromagnetic hold valve 6 is kept energized.

If it is determined in the above step IV that the lift arm is not in the first dead zone, the process proceeds to step VII and the lift arm 4
Is determined with respect to the set position. When the lift arm is above the set position, the process shifts to step VIII to control the lowering of the lift arm. If the lift arm is below the set position, the process shifts to the IX step to control the lift of the lift arm. Then, in this state, the electromagnetic hold valve 6 maintains the energized state as in the Xth step.

If it is determined in step III that the tilling work is not performed, the process proceeds to step XI, and the lift arm 4
It is determined whether it is within the dead zone. If the lift arm is in the second dead zone, the process proceeds to the XII step, and it is determined whether or not the holding time within the second dead zone is within the range of the time Δt set by the delay timer 18. If the set time has been exceeded, the process proceeds to the XIII step to stop energizing the solenoid 6b of the electromagnetic hold valve 6, and the valve 6 is switched to the hold position. If it is within the set time range, the process proceeds to the Vth step and thereafter, and the hold valve 6 is kept at the open position.

If it is determined in step XI that the lift arm is not in the second dead zone, the process proceeds to step IV.

The reason why the delay timer 18 is provided as described above to delay the timing of switching the electromagnetic hold valve 6 to the hold position is as follows. That is, when the electromagnetic hold valve 6 is operated immediately when the rotary claw 2 shifts from the first dead zone to the second dead zone, the electromagnetic hold valve 6 can be operated even when the raising and lowering is repeated during the tilling operation. It is repeated to energize or block the energization. If this repetition becomes intense, problems such as intense wear of the electromagnetic hold valve 6 occur.
Therefore, the delay timer 18 is operated to switch the electromagnetic hold valve 6 only after a certain time has elapsed.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention.
FIG. 2 is a block diagram showing an electric circuit, FIG. 2 is a flowchart, FIG. 3 is a timing chart, and FIG.
Explanatory drawing showing the range between the dead zone and the second dead zone, FIGS.
Fig. 5 shows a conventional control device. Fig. 5 is an explanatory diagram showing the relationship between an agricultural tractor and its hydraulic control circuit. Fig. 6 is a block diagram showing an electric circuit. Fig. 7 is a timing chart. It is a chart figure. 1 ... body, 2 ... rotary claw as tillage member, 5 ...
... Control cylinder, 6 ... Electromagnetic hold valve, V ... Electromagnetic valve mechanism, 10 ... Control unit, 11 ... Comparison unit, 12 ... Position detection unit, 13 ... Calculation unit, 14 ... Target position setting unit , 15... A first dead zone setting section, 17... A second dead zone setting section, 18.

Claims (1)

(57) [Claims] 1. A tilling member such as a rotary claw connected to a vehicle body, a hydraulic cylinder for controlling a height position of the tilling member, and an electromagnetic hold for locking the control cylinder to maintain the height position of the tilling member. The height position of the tilling member is set in an agricultural tractor tillage depth control device including a valve and an electromagnetic valve control mechanism that supplies pressure oil to the control cylinder or returns the pressure oil to the tank. Target position setting unit, a first dead zone setting unit for setting a dead zone with respect to the target position set by the target position setting unit, a position detecting unit for detecting the actual position of the tilling, and detection by these position detecting units A comparison unit that compares whether the actual position of the tillage member that has been set is within the range of the first dead zone width, and a second dead zone setting unit that sets a dead zone to a width larger than the first dead zone width.耘部 member is provided with a delay timer which operates when departing from the second dead zone width,
A tillage depth control device for an agricultural tractor configured to hold a position of a tilling member by closing an electromagnetic hold valve after a predetermined time counted by a delay timer after the tilling member is positioned in a second dead zone.