JPH0714281B2 - Automatic lifting control device for agricultural work vehicles - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic lifting control device for an agricultural work vehicle equipped with a working machine such as a tilling machine.

○ Conventional technology As an automatic lifting control device for this type of work machine,
-36721 "ground work vehicle" is known. In the known technique, the solenoid valve of the work implement lifting device is intermittently provided in order to increase the work efficiency of the work implement by controlling the descending speed of the work implement in two stages and prevent the dashing phenomenon due to an instantaneous increase in load at the time of grounding. The work machine is provided with an intermittent signal generator for driving, and is configured to supply the intermittent signal after the working machine descends to a predetermined position.

[Problems to be Solved by the Invention] In the above-mentioned known technology, the stop valve for fixing the position of the working machine during non-working and the slow return valve for adjusting the descending speed of the working machine (hereinafter collectively referred to as slow return, stop valve Operation) is open to the user and any adjustment is possible, but if work is performed without opening the stop valve completely during work, or if the work machine is slowed down depending on the work conditions. If the slow return / stop valve is throttled to lower the valve, the intermittent signal is unconditionally supplied after the set position, causing a slower deceleration than necessary and causing a decrease in work efficiency due to an increase in the descent time. . In addition, when the machine tilts in the front-back direction due to unevenness in the field, the deceleration time when the work machine descends is inappropriately too late or too early compared to when the machine is horizontal, Even when the deceleration time can be adjusted by the manual operation tool, there is a problem that the adjustment operation itself is troublesome.

○ Means for Solving Problems The present invention relates to a working machine position sensor (1); a working machine tilling depth setting device (2); a working machine vs. this machine position setting device (3).
And; a working depth sensor (4); a hydraulic lifting device (7) including a solenoid valve (5) and a slow return stop valve (6) for lifting and lowering the working machine; and a hydraulic lifting device (7). A solenoid valve drive circuit (8) for switching between continuous energization and pulse energization for the solenoid valve (5); Operating speed detecting means for detecting operating speed (9)
And a central processing unit (11) including the setting device and a signal comparison calculation control circuit (10) for issuing a control signal to the working machine lifting solenoid valve by comparing and calculating the sensor signal, the control operation thereof According to the present invention, there is provided an automatic lifting control apparatus for an agricultural work vehicle, which is characterized by solving the above problems.

○ Effect of the invention When the slow return stop valve (6) of the hydraulic lifting device (7) is in the open position, the work implement descends at a high speed, and the descending work implement position sensor signal is output by the operating speed detector. After the sampling at a constant time interval, the signal is converted into a descent rate by calculation and time processing, and is input to a signal comparison, calculation and control circuit. Signal comparison, calculation,
The control circuit generates the descent rate and the time rate of change of the descent rate by calculation, and constantly monitors whether the rate of change of the negative polarity is constant, and after the descent rate of the work machine exceeds a certain speed or more. When the working machine descends at a high speed and enters the ground when it has reached a certain negative change rate, the working machine position sensor indicates that the working machine has descended to the set working depth of the setter. Judging by the signal, the descent operation until automatic stop is performed by continuously energizing the drive of the working machine descent solenoid valve,
Switch to pulse energization and decelerate. On the other hand, when the slow return stop valve is not fully closed and is slightly open, the work equipment descending speed is slower than the above-mentioned high speed, but if it is below a certain speed, that is, it does not lead to dashing or engine stop. In the case of such a low speed descent, since the speed does not reach the above-mentioned constant speed, the control operation for preventing an excessive slow speed descent is performed by not performing the deceleration operation switching described above. Therefore, no matter what the valve opening / closing state and the working machine tilting in the front-rear direction, the shortest time and the best working machine lowering operation can be obtained.

Example In the example shown in FIG. 2, a working machine position sensor (1), a working machine tillage depth setting device (2), a working machine-to-machine position setting device (3), and a working depth sensor (4). Central processing unit (1
An analog switch (12) and an A / D converter (13) are interposed between the one-chip microcomputer (11a) and the analog switch (1) that function as a central processing unit (11).
2) Attach the controller (14) equipped with the A / D converter (13) and the solenoid valve drive circuit (8) to the work machine or the proper place of the machine.

The work implement position sensor (1) detects the attitude of the work implement (cultivator) against the main unit (tractor), and the detection signal is an analog voltage signal, which is sent to the A / D converter via an analog switch in the controller. The one-chip microcomputer, which is converted into a digital signal by a digital camera, is loaded into the one-chip microcomputer. The one-chip microcomputer uses the control program to generate a constant time signal from the built-in timer signal.
t)-(t) calculation], the operating speed of the working machine can be detected. The work machine-to-machine position setter (3) is
Set the relative position of the work machine to the machine. The working machine tillage depth setting device (2) sets the ground elevating position. The tilling depth sensor (4) detects the ground position of the working machine.

The hydraulic lifting device (7) has a hydraulic cylinder having a lift cylinder (16) for connecting the machine and the working machine and rotating a lift arm (15) for lifting and lowering the working machine with respect to the machine. Including a control mechanism, as shown in FIG. 3, a solenoid valve (5) and a slow return stop valve (6)
Besides, it includes a hydraulic pump (17), a choke valve (18), a relief valve (19) and a safety valve (20). In FIG. 3, (21) is a lower link.

The one-chip microcomputer (11a) is a work machine position sensor (1) by a program embedded in the one-chip microcomputer.
And the function as the operating speed detecting means (9) for detecting the operating speed of the working machine by time-processing [(t + Δt) − (t) calculation] the detection signal of {(t + Δt) −
(T)} / (t) descending speed change rate is generated, and the signal of the lift arm position sensor and the signal of the working depth setting machine are monitored to check whether the working machine is descending at a certain speed or more. After the negative speed change above a certain level occurs while descending at the above speed, or whether the position of the working machine has descended to the set plowing depth position, after making comparison and judgment, the control described in the above-mentioned invention action It has a function of a signal comparison operation control circuit (10) that operates.

The solenoid valve drive circuit (8) supplies the solenoid valve (5) with continuous energization and pulse energization in a freely switchable manner, and when the pulse energization control signal from the signal comparison calculation control circuit (10) is received. The pulse energization state is set, and the continuous energization state is set when the continuous energization control signal comes in.

When the slow return stop valve (6) is open, the descent speed of the work implement is increased until the tilling part (rotary tilling claw) touches the ground, and the descent speed N1 is the highest at the touchdown point (a). The descent rate decreases due to the increase in load resistance due to grounding, and the rate of increase in speed reverses negatively. The decrease of the descending speed is performed by the time processing of the detection signal of the work machine position sensor (1) in the central processing unit (11) [(t + Δt)-
The ground is detected at the ground detection point (b) by (t) <0].

The solenoid valve drive circuit (8) is changed to the pulse energized state at the timing of the point (c) after the point (b). As a result, the working machine ascending / descending speed becomes the descending speed of N2.

In the open state of the slow return stop valve (6), continuous energization is continued even after the ground contact, and it is controlled so that unnecessary deceleration is not performed until it reaches a predetermined plowing depth value and stops.

In any case, the work machine starts to descend by operating the controller start switch (not shown).
When the tilling depth value by the tilling depth sensor (4) matches the set value of the setter (2), the solenoid valve drive circuit (8) is stopped by the coincidence judgment of both by the calculation by the central processing unit (11), The solenoid valve (5) is closed to stop the descent of the lift cylinder (15) to maintain a predetermined working depth value.

<Effects of the Invention> Like the known art, the present invention has effects such as prevention of dashing of the machine, damage of nails and other members of the working machine, reduction of grounding shock of the working machine, and the like. When the deviation of the deceleration speed of the work implement due to the forward-backward tilt is eliminated and the slow return stop valve is throttled to slow down the descent speed, continuous energization is continued without switching to pulse energization. It is effective in improving work efficiency as compared with the known art.

Further, according to the present invention, the operating speed of the working machine is detected by the operating speed detecting means (9) for processing the detection signal of the working machine position sensor (1) for the calculation time to detect the operating speed of the working machine. By detecting the change in speed, it is possible to detect the time when the working machine plunges into the ground while descending.Therefore, a setter for setting the set descending position is unnecessary, and the control mechanism can be simplified. effective. Further, since the control timing is determined by detecting the change in the operating speed, there is an effect that the timing for speed switching is surely performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an automatic lifting control device for an agricultural work vehicle according to the present invention, corresponding to the claims. FIG. 2 is a block diagram showing the outline of an automatic lifting control device for an agricultural work vehicle according to the present invention. FIG. 3 is a hydraulic circuit diagram of the hydraulic lifting device. FIGS. 4 and 5 are graphs showing the relationship between the ground contact height and the work implement descending speed. FIG. 4 shows the case where the slow return stop valve is in the open state, and FIG. 5 is not fully closed. It shows the case of the state that is slightly open. 1 …… Working machine position sensor 2,3 …… Setting device 4 …… Plumage depth sensor 5 …… Solenoid valve 6 …… Slow return / stop valve 7 …… Hydraulic lifting device 8 …… Solenoid valve drive circuit 9 …… Operating speed detection means 11 ... Central processing unit

Claims (1)

[Claims] A hydraulic lifting device (7) including a hydraulic cylinder (16) for driving a working machine / lifting lift arm (15) and a slow return stop valve (6), and a hydraulic cylinder (16). A working machine lifting solenoid valve (5) to be driven, and the working machine lifting solenoid valve (5) is automatically operated so that the working machine is lowered from a raised position and automatically stopped at an arbitrary position in the ground. An agricultural work vehicle equipped with a work depth control device (14), wherein the working machine is descending, and the detection signal of the working machine position sensor (1) is time-processed to determine the operating speed of the working machine by the operation detecting means (9). If the descent speed is equal to or higher than a predetermined speed before entering the ground, the operation detecting means (9) detects that the working machine has entered the ground by grading the operating speed of the working machine. The solenoid valve (5) for raising and lowering the working machine is switched from continuous energization to pulse energization Together to slow descent until automatically stopped, when the descending speed of the working machine is constant speed below before rush into the ground is changed at a predetermined tilling depth position,
An automatic lifting control device for an agricultural work vehicle, comprising a control device that performs a control operation in which the slow descent operation is not performed until the work machine plunges into the ground and then automatically stops.