JPH0714282B2 - 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.

In the present invention, the working machine is descending, and the processing signal of the working machine position sensor (1) is time-processed to process the detection signal of the working machine with respect to the machine displacement signal, thereby changing the working machine operating speed signal. When the descent speed is a high-speed descent of a certain speed or more before entering the ground, it is detected that the working machine has rushed into the ground by detecting the speed of operation of the working machine, and immediately after the detection Until the machine-elevating solenoid valve (5) is switched from continuous energization to pulse energization with a variable duty ratio, and the duty ratio is gradually reduced to automatically correspond to a predetermined operating curve until it is automatically stopped at a predetermined plowing depth position. In the case of slow descent and when the descent speed of the work implement is lower than a certain speed before entering the ground, do not perform the slow descent operation until the work implement automatically stops after entering the ground. Controls that perform control actions The present invention provides an automatic lifting control device for an agricultural work vehicle, which is equipped with a control device.

○ 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 being sampled at fixed time intervals, it is converted to the descending speed by performing time processing and the descending speed of the working machine exceeds a certain speed or more, and then a constant negative change rate is reached. Is descending at high speed,
It is judged that it has entered the ground, and after that it is judged from the work machine position sensor signal that it has descended to the set plowing depth of the setter, and the descent operation until automatic stop is performed by the work equipment lowering solenoid valve. The drive is immediately switched from continuous energization to pulse energization with a changeable duty ratio, and the duty ratio is gradually reduced to decelerate the operation so as to correspond to a predetermined operation curve. 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. In this way, the work equipment descending speed is detected, and first, after contacting the ground with the descending speed kept as it is, whether or not the descending positioning to the set plowing depth is acceptable or not is compared with a threshold value that serves as a reference for constant speed comparison. By comparing the results, it is decided in advance whether or not to switch to slow descent, and secondly, the change in the work equipment descent speed is monitored, and the grounding of the work equipment is grounded at a time change rate at which the sharp decrease in descent speed is above a certain level The control circuit is configured so as to generate an operation start signal when it is detected based on the occurrence and the speed is slowly lowered. Therefore,
The shortest time and the best work machine descending operation can be obtained regardless of the valve open / close state and the work machine tilting in the front-rear direction.

Example In the example shown in FIG. 1, a working machine position sensor (1), a working machine tilling depth setting device (2), a working machine-to-machine position setting device (3), and a working depth sensor (4). , One-chip microcomputer that performs control operations such as taking in sensor signals and operation switch signals by a built-in program, comparing sensor signals with built-in data, comparing sensor signals with each other, calculating sensor signals, outputting signals to solenoid valve drive circuits, etc. (11), A / D converter (analog-to-digital converter) that converts analog signals to digital signals (13), analog switch (analog that selectively connects various sensor signals to A / D converter by sensor selection signal of one-chip microcomputer) Controller (12), electromagnetic valve drive circuit (8) that amplifies weak electromagnetic valve drive signal from one-chip microcomputer, etc. Install the la (14) in place on the implement.

The work implement position sensor (1) detects the posture of the work implement (plow work implement) with respect to the main body (tractor), and the detection signal is an analog voltage signal and is passed through the analog switch (12) in the controller (14). A / D Converter (13)
Converted to digital signal by one-chip microcomputer (11)
Is taken into. The one-chip microcomputer (11) performs time processing [calculation of (t + Δt)-(t)] by calculating the signal of the work machine position sensor with a constant time signal generated by a built-in timer counter according to its control program. The operating speed of the work machine can be detected. The work machine-to-machine position setting device (3) sets the relative position of the work machine to the machine. The working machine tillage depth setting device (2)
Set the elevation position to the ground. 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 (11) processes the detection signal of the working machine position sensor (1) by time processing [calculation of (t + Δt)-(t)] by a program embedded in the one-chip microcomputer to detect the working speed of the working machine. And ((t + Δt)-(t)} as the operation speed detecting means for
/ (T) descending speed change rate is generated, and the signal of the lift arm position sensor and the signal of the tilling depth setting machine are monitored, and the working machine is descending at a certain speed or more, or at a certain speed or more. Comparison, judgment, and calculation of the operating speed change rate, such as whether a negative speed change more than a certain amount occurred during the descent, or whether the position of the working machine dropped to the set plowing depth position, and compare it with the programmed operating curve. And a solenoid valve drive circuit control means for switching from continuous energization to pulse energization and determining the duty ratio of the pulse, and having the function of a signal comparison calculation control circuit for performing the control operation described in the section of the action of the invention. is there.

The flow chart for fetching the sensor and setting device signals of the one-chip microcomputer (11) is as shown below.

When the sensor selection signal of the one-chip microcomputer output port is sent to the analog switch (analog multiplexer), only the selected sensor signal and setter signal are connected to the analog input terminal of the A / D converter.

One-chip microcomputer can be used as an analog to A / D converter.
Output digital conversion start signal to A / D converter.

The A / D converter performs analog-to-digital conversion (usually several μsec to several tens of μsec) and sends a completion signal to the one-chip microcomputer when the conversion is completed.

The one-chip microcomputer sends the continuous signal to the A / D converter.

The A / D converter that receives the continuous signal outputs the A / D converted data to the data bus.

The one-chip microcomputer reads the A / D conversion data on the data bus.

Return to and repeat.

The solenoid valve drive circuit (8) supplies the solenoid valve (5) with continuous energization and pulse energization in a freely switchable manner, and is instructed when the pulse energization control signal from the one-chip microcomputer (11) comes in. The duty ratio is set to the pulse energization state, 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). [Part P of operation curve in FIG. 3]. Although the descending speed decreases due to the increase of the load resistance due to grounding and the increasing rate of speed reverses to the negative, the present invention controls the solenoid valve (5) so that the subsequent operation curve becomes as shown in FIG. 3Q. . That is, the one-chip microcomputer (11) calculates an operating curve Q based on the tilling depth value obtained from the tilling depth sensor (4) and the descending speed of the calculation result of the detection signal by the work implement position sensor (1) and the program. Continuous conduction [drive waveform in FIG. 4 (a) corresponding to Q1 in FIG. 4] → pulse conduction [drive waveform in (b) corresponding to Q2] → pulse conduction with a small duty ratio [ (C) drive waveform corresponding to Q3] Pulse energization smaller than the duty ratio [(D) drive waveform corresponding to Q4] is automatically controlled to change.

When the slow return stop valve (6) is open,
Continuous energization is continued even after the ground contact, and as shown in FIG.

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 setting device (2), the solenoid valve drive circuit (8) is stopped by the coincidence judgment of both by the calculation by the one-chip microcomputer (11), The solenoid valve (5) is closed to stop the descent of the lift cylinder (15) to maintain a predetermined working depth value.

Next, the one-chip microcomputer (11) will be described with reference to FIGS. 5 to 10.

FIG. 6 shows the outline of the one-chip microcomputer (11), and its program flow charts are the main program of FIG. 7, the subroutine program of FIG. 8, and the program of FIG. 9 (a).
(B) (c) (d) (e) is the same as the timer interrupt program, and the control program operation is as follows.

Program the timer interrupt program to execute at 5msec intervals using the timer counter built in the one-chip microcomputer. By doing so, an interrupt occurs at 5 msec intervals and a timer interrupt is executed.

The timer interrupt routine performs A / D conversion of analog signals from various sensors and setting devices, generates speed and speed change data by capture and calculation, compares the data to detect the grounding of the work machine, and the position of the work machine at the time of grounding. From the memory of, the current position after grounding is divided into zones, and the duty of pulse drive is automatically set and executed according to the zone. The program flow is controlled by various switches and counters in the RAM working area.

FIG. 5 shows the function of the one-chip microcomputer (11) according to the embodiment of the present invention.
The operating speed change rate detection means (b) and the solenoid valve drive circuit control means (c) are as follows.

○ Operating speed detection means (a) 5m using timer counter built in one-chip microcomputer
When a timer interrupt is generated at a minute time interval of sec, the signal of the work machine position sensor is captured after A / D conversion in the timer interrupt routine, and the old and new data is subtracted at a 5 msec time interval (new data-old data ) / 5msec = speed is obtained.

○ Operating speed change rate detecting means (b) Similarly, the amount of change can be obtained by subtracting the old and new data at 5 msec time intervals from the descent speed data obtained by the operating speed detecting means (a) The number of times that the change amount of occurs occurs is counted, and if it occurs several times, the ground switch is set to "1" to change the flow of the program).

Solenoid valve drive circuit control means (c) operating curve storage means (d), operating curve comparison means (e)
And pulse duty ratio calculation path drive signal generating means (f), the position of the working machine position sensor at the time of grounding is stored in the grounding position data, and the subtraction from the current working machine position sensor in FIG. )
~ (D) ((e)) Zones are divided, the pulse duty is determined for each zone, and a solenoid valve drive signal for executing pulse drive is generated. The pulse duty ratio calculation and signal generation means (e) are As described above, the timer interrupt is generated at an interval of 5 msec, and pulse driving with a predetermined duty ratio is performed (FIG. 10 shows an example of pulse driving with 1/5 duty).

<Effects of the Invention> Like the known technology, the present invention has effects such as prevention of dashing of the main body, prevention of damage to claws and other members of the working machine, reduction of grounding shock of the working machine, and the like. By changing it to a desired operating characteristic (gradual deceleration curve) to reduce ground shock without lowering work efficiency, and slowing down the slow return stop valve to slow down the descent, switch to pulse energization. The continuous energization is continued without performing the above, and compared with the known technology, there is an effect that the working efficiency is always improved as the optimum operating characteristic.

In addition, the present invention can use a one-chip microcomputer that functions as a central processing unit (CPU) in responding to an operation curve by changing the duty ratio, and can reduce costs by mass production of a control mechanism by microcomputer control. At the same time, the change of the optimum operation curve due to the change of the field condition and the working condition can be easily dealt with by changing the microcomputer program.

Further, according to the present invention, when the working machine is descending, the detection signal of the working machine position sensor (1) is time-processed to detect the operating speed of the working machine and to detect a change in the operating speed. Since the time when it rushes into the ground is detected,
The setting device for setting the set lowering position is unnecessary, and has the effect of simplifying the control mechanism. 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 the outline of an automatic lifting control device for an agricultural work vehicle according to the present invention. FIG. 2 is a hydraulic circuit diagram of the hydraulic lifting device. FIG. 3 is a graph showing the relationship between the ground contact height and the descending speed of the working machine. FIG. 4 is a solenoid valve drive waveform diagram. FIG. 5 is a block diagram showing the functions of the one-chip microcomputer (CPU). FIG. 6 is an explanatory diagram showing a component placement and call memory placement in the same manner. 7 to 9 show the same program flow chart, FIG. 7 is a main program, and FIGS. 9 (a), (b), (c) and (d) are timer interrupt programs. FIG. 10 is an explanatory diagram of pulse driving with a duty ratio of 1/5. 1 …… Working machine position sensor 2 …… Setting device 4 …… Plumage depth sensor 5 …… Solenoid valve 6 …… Slow return / stop valve 7 …… Hydraulic lifting device 8 …… Solenoid valve drive circuit 11 …… One chip Microcomputer (CPU)

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 working depth control device (14), wherein when the working machine is descended and positioned to an arbitrary plowing depth position, the descending speed is not less than a certain speed before plunging into the ground. In this case, it is detected that the working machine has rushed into the ground by detecting the operating speed of the working machine, and after that, the solenoid valve (5) for raising and lowering the working machine is continuously energized so that the duty ratio can be changed by pulse energization. To switch to the desired operating curve Together to slow drop to automatically stop at a predetermined tilling depth position gradually decreases the I ratio, when the descending speed of the working machine is constant speed below before entered the ground, the
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.