JPS6249001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mobile agricultural machine, and more particularly to a steering control device for a mobile agricultural machine in which steering is automatically controlled by a hydraulic cylinder.

[Prior Art] In recent years, with the rapid development of control technology, automation of mobile agricultural machinery has been carried out. For example, an automatic rice transplanter detects planting rows (seedlings) and automatically controls direction while traveling to plant the seedlings. In this case, directional control of the mobile agricultural machine is performed by driving a steering mechanism using a hydraulic cylinder. Furthermore, mobile agricultural machinery is used under extremely poor operating conditions, such as traveling through rice fields, and when attempting to move straight with the steering wheel free, the straight-line stability is extremely reduced due to the external force applied to the front wheels.

In order to solve these problems, the steering devices in conventional automated mobile agricultural machines are
During straight-ahead control, the input and output oil passages of the hydraulic cylinders are closed to prevent the piston of the hydraulic cylinder from moving, thereby locking the steering mechanism and improving stability during straight-ahead travel.

[Problems to be Solved by the Invention] However, in the mobile agricultural machine configured as described above, the steering is locked when the machine goes straight due to automatic control, so it cannot be operated manually. This had to be done after the automatic control circuit was set to OFF. For this reason, it was not possible to give priority to manual operation, which was disadvantageous in terms of safety.

[Means for Solving the Problems] Therefore, an object of the present invention is to provide a steering control device for a mobile agricultural machine that is suitable for manual priority control and has extremely high straight-line stability.

In order to achieve such an objective, the present invention
A steering device connected to a manually operated steering wheel, and a hydraulic cylinder for automatic direction control connected to the steering device, so that manual direction control by the steering wheel and automatic direction control by the hydraulic cylinder can be performed, In a mobile agricultural machine configured to close an input/output hydraulic passage of a hydraulic cylinder to stabilize straight-line movement during straight-line movement under automatic direction control, a mobile agricultural machine is provided between the input-output oil passage of the hydraulic cylinder during automatic direction control during manual direction control using a handle. The present invention is characterized in that a switching valve is provided which operates to connect the input and output oil passages to free the hydraulic cylinder, so that the automatic direction control circuit passes during manual direction control.

[Example] Hereinafter, a case in which a steering control device for a mobile agricultural machine according to the present invention is applied to an automatic rice transplanter will be described in detail with reference to the drawings.

FIGS. 1 to 3 show a side view, a front view, and a plan view of an embodiment of an automatic rice transplanter to which the present invention is applied, and the automatic rice transplanter 1 is equipped to change the direction of travel. The vehicle body is supported by two front wheels 2 and two rear wheels 3 as drive wheels. At the rear of the automatic rice transplanter 1, an automatic rice transplanter 5 is provided which is supported on the rice field by a float 4.

This automatic planting device 5 has a structure similar to the planting part of a commonly used rice transplanter, in which a planting claw 6 moves back and forth between the end of a seedling platform 7 and the ground surface. By doing this, the seedlings placed on the seedling stand 7 are planted at regular intervals. Further, on both sides of the front part of the automatic rice transplanter 1, direction sensor units 9a and 9b are provided which are moved up and down by cylinders 8a and 8b. The direction sensor units 9a and 9b are used to detect the planting row 10 and control the running direction, and are equipped with a float 11a to keep the detection position in the height direction with respect to the planting row 10 constant. , 11b are provided. Further, the direction sensor units 9a, 9b include direction sensors 12a, 12b for detecting the planting row 10 and performing left turn control, and direction sensors 13a, 13 for performing right turn control.
b is provided, and this direction sensor 12a, 1
3a, 12b, and 13b face each other at a predetermined distance, thereby detecting the position of the planting row 10 passing between these two-way sensors.

In addition, the steering portion including the front wheels 2 for changing the running direction is connected to the handlebar 15 with normal play so that manual control can be performed.
As shown in Figure 4, this steering part has
A cylinder 14 is provided for controlling the steering during automatic direction control. Furthermore, this steering portion is provided with a potentiometer 14a whose sliding piece moves in conjunction with the movement of the steering wheel. The signal is extracted and used as a control signal for an automatic direction control circuit, which will be described later.

Next, the cylinders 8a and 8b for vertically moving the above-mentioned direction control unit in the automatic rice transplanter configured as described above and the cylinder 14 for steering control are controlled by a hydraulic system as shown in FIG. has been done. That is, a constant pressure hydraulic source 17 constituted by a hydraulic pump P and a pressure regulating valve 16
The output oil is produced by solenoid valve 1 for switching the oil path direction.
The output oil of the solenoid valve 18 is supplied to the cylinder 8b via the solenoid valve 19, and the output oil of the solenoid valve 19 is supplied to the cylinder 14 via the solenoid valve 20. It is configured as follows.

The electromagnetic valves 18 and 19 include solenoids 21a and 21b for switching valves for supplying hydraulic pressure to the cylinders 8a and 8b to raise the direction sensor units 9a and 9b, and solenoids 21a and 21b for supplying hydraulic pressure to the cylinders 8a and 8b to raise the direction sensor units 9a and 9b. Solenoids 22a and 22b are provided for switching valves for returning oil to the oil reservoir and lowering direction sensor units 9a and 9b. Further, the electromagnetic valve 20 includes a solenoid 23 that switches the valve to contract the cylinder 14 to turn the steering wheel to the left, and a solenoid 24 to switch the valve to extend the cylinder 14 and turn the steering wheel to the right. It is provided. Note that an electromagnetic valve 25 is provided between the input and output oil passages of the cylinder 14, and is configured to shoot between both oil passages in a normal state. 14 is free to operate and manual direction control can be performed using the handle 15. When the solenoid 26 provided in the electromagnetic valve 25 is driven to switch the valve of the electromagnetic valve 25, the above-mentioned cylinder 14 The shot oil passage of the cylinder 14 is disconnected and the solenoid valve 2
It is kept under the control of 0.

Next, a control circuit for controlling the above-mentioned solenoid will be explained. FIG. 6 shows an embodiment of the control circuit, in which 27a is a left direction sensor unit vertical movement switch whose common terminal a is connected to the positive electrode, and fixed terminal b is a left direction sensor unit vertical movement switch whose common terminal a is connected to the positive electrode. It is connected to the negative electrode via an upper limit switch 28a that defines the limit and a solenoid 21a, and the fixed terminal c is connected to the negative electrode via a solenoid 22a. 27b is a right-hand sensor unit vertical movement switch whose common terminal a is connected to the positive pole, and the fixed terminal b is connected to the negative pole through an upper limit switch 28b and solenoid 21b that regulates the upper limit of the rise of the right-hand sensor unit 9b. The fixed terminal c is connected to the negative electrode via the solenoid 22b.

Reference numerals 29a and 29b are steering switches provided on the handle 15. Normally, both switches are in the off state, and when the handle 15 is manually turned to the left, the normal play range of the handle is changed. After that, the steering switch 29a is turned on, and when turned to the right, the steering switch 29b is similarly turned on. 30 is a relay operated by the OR output of the steering switches 29a and 29b, and 30a is a normal cross contact of the relay 30 which controls the power supply of the direction sensor, which will be described later, and these constitute a manual control circuit 31. The cathodes of 32a and 32b are commonly connected, and the anode is connected to the switch 27a.
30b is a relay 3 connected via a solenoid 26 between the cathode and negative electrode of the diodes 32a and 32b.
0 normal cross contact, 33 direction sensor 12
A left turn signal terminal that takes out the OR output of a and 12b,
34 is a right turn signal terminal that takes out the OR output of the direction sensors 13a and 13b; 35 is a straight signal terminal that detects the absence of both left and right turn signals by the Noah gate 36 and takes out a straight signal; 37 is a servo for direction control. transistors 38 to 40 whose emitters are grounded and are turned on by output signals from signal terminals 33 to 35; each connected to the collectors of the transistors 38 to 40, and whose other ends are commonly connected at point M; resistors 41a to 41c, a comparator 43 which takes the potential at point M as an inverting input, and takes the output of the potentiometer 14a as a non-inverting input via a small resistor 42,
A comparator 44 which has a point potential as a non-inverting input and an output signal of the potentiometer 14a as an inverting input, an amplifier 45 which amplifies the output signal of the comparator 43 and drives the solenoid 23, and an amplifier 45 which amplifies the output signal of the comparator 44 and drives the solenoid 23. and an amplifier 46 that drives the solenoid 24.

Note that the resistance value of the resistors 41a to 41c is 4.
The relationship is 1a<41c<41b, and each resistance value is set so that when the transistor 38 is turned on, the M point is 2V, when the transistor 39 is turned on, the M point is 8V, and when the transistor 40 is turned on, the M point is 5V. It is set.

The operation of the control circuit with the above configuration will be explained below.

First, the sensor unit vertical movement switch 27a,
27b are both fixed contacts b as shown in FIG.
If the solenoid 21a,
21b operates until the limit switches 28a, 28b are turned off, and accordingly, the solenoid valves 18, 1
9 operates in the direction of extending the cylinders 8a, 8b, both direction sensor units 9a, 9b are raised.

Next, for example, right direction sensor unit switch 2
When 7b is operated and set to the fixed contact c side, the solenoid 22b is activated and the solenoid valve 19 returns the oil in the cylinder 8b to contract the cylinder.
As shown in FIG. 2, the direction sensor unit 9b descends and the float 11b comes into contact with the ground and stops.
On the other hand, when the switch 27b switches to the fixed contact c side, the positive power supply - switch 27b - diode 32b
-Contact 30b-Solenoid 26-A current flows through the negative power supply path and the solenoid 26 is activated, and in conjunction with this, the solenoid valve 25 disconnects the short path between the input and output oil passages of the cylinder 14, turning the cylinder 14 into a solenoid valve. Automatic direction control operation is initiated under the control of 20.

Next, when the planting row passes between the direction sensors 12b and 13b provided on the lowered direction sensor unit 9b without touching both sensors, all the direction sensors 12a, 12b, 13
a, 13b are off. Therefore, no output is generated at the right turn signal terminal 34 and the left turn signal terminal 33.
However, the Noah gate 36 detects that both the right turn signal and the left turn signal are off, and sends a straight signal to the straight output terminal 35. This straight signal turns on the transistor 40, and as a result, the potential at point M increases.
Set to 5V. In this case, if the steering wheel is pointing straight ahead, the output of the potentiometer 14a will be 5V, and the output of the comparator 43,
Both inputs of 44 match, no output is sent out, and the rice transplanter continues to move straight.

Next, if the rice transplanter deviates to the left with respect to the planting row due to some reason, for example, the direction sensor 13b
The planting row 10 comes into contact with this, and the direction sensor 13b, which is displaced and activated by a weak external force, is turned on. As a result, a right turn signal is sent from the right turn signal terminal 34, turning on the transistor 39, and the output of the NOR gate 36 becomes "O" due to the output of the direction sensor 13b, turning off the transistor 40. Therefore, the potential at point M becomes 8V, which is set by the value of the resistor 41b, and the comparator 44 outputs a comparison output with the 5V output of the potentiometer 14a in the straight traveling state. Incidentally, 8V and 5V are also applied to the input of the comparator 43, but since their polarities are reversed, no output is generated.

The output signal of the comparator 44 detected in this manner is amplified by an amplifier 46 and then supplied to the solenoid 24 to drive the solenoid 24. When the solenoid 24 is activated, the solenoid valve 20 shown in FIG. 5 is switched to extend the cylinder 14. As a result, the steering is driven as the cylinder 14 extends, and the front wheels rotate to the right, causing a right turn. In this case, when the steering wheel is driven in the right-turn direction, the sliding piece of the potentiometer 14a is moved in the direction in which the resistance increases (in the sixth direction).
(upward in the figure), and the output voltage of the potentiometer 14a rises from 5V accordingly. Then, when the steering wheel is driven to a right turn angle where the output voltage of the potentiometer 14a reaches 8V, the output of the comparator 44 is turned off, and the solenoid 24 is accordingly restored.
When the solenoid 24 is restored, the solenoid valve 20 also switches to the fifth
The state shown in the figure is restored and the cylinder 14 is locked in that state. Therefore, the rice transplanter continues to turn right in this state.

As the rice transplanter moves forward while making a right turn in this manner, the contact between the planting row (planted seedlings) 10 and the aforementioned direction sensor 13b is released because the machine body moves in the direction approaching the planting row. Direction sensor 13b is turned off. When the direction sensor 13b is turned off, the transistor 39 is turned off, a straight forward signal is sent from the NOR gate 36, and the transistor 4
Only 0 is on. When the transistor 40 is turned on, the potential at the point M becomes 5V, and an output is sent only from the comparator 43, contrary to the above. The output of the comparator 43 drives the solenoid 23 via an amplifier 45. When the solenoid 23 is actuated, the solenoid valve 20 switches to cause the cylinder 14 to contract. As a result, the steering wheel is rotated in the opposite direction to that described above and returned to the straight direction.

Then, when the steering goes straight, the output of the potentiometer 14a decreases to 5V, so at the time when the steering goes straight, the output of the comparator 43 turns off, and accordingly the solenoid 23 and the solenoid valve 20 is restored and the steering locks while driving straight. Travel control along the planting row 10 is performed by performing such an operation every time the vehicle shifts in the left-right direction with respect to the planting row 10. Note that the operating range of the steering during this automatic control is small and within the range of play of the steering wheel 15, so the steering wheel 15 does not rotate and the switches 29a and 29b remain off. In this way, rice planting is progressed while performing automatic direction control, and when the rice is located at the edge of the planting surface (rice field), the sensor unit vertical movement switch 27a is switched to the fixed terminal b side. The solenoid 21a is driven to raise the direction sensor unit 9b, and the bidirectional sensor units 9a,
9b is raised, manually operate the handle 15 to rotate the sensor unit 9a, and when the rotation is completed, switch the sensor unit vertical movement switch 27b to the fixed terminal c side and turn the sensor unit 9a in the opposite direction from the case described above. is lowered and automatic direction control is performed in the same manner as described above.

Next, if you try to manually turn the steering wheel 15 in a certain direction during automatic direction control, the steering switches 29a, 29b will be turned off after the range of play has passed.
One of them turns on, and the relay 30 operates accordingly. When the relay 30 operates, the contact 30a opens and the direction sensors 12a, 12b,
The power supply to 13a and 13b is cut off to stop their functions. In addition, since the contact 30a is opened in conjunction with the operation of the relay 30, the solenoid 26 is restored in any state, and the electromagnetic valve 25 is also restored and the input/output oil passage of the cylinder 14 is shut off. (pass) to do. Therefore, the cylinder 14 becomes free, and direction control can be easily performed by manual operation of the handle 15, resulting in a safe configuration with priority given to manual operation.

In addition, in the above explanation, the direction sensor of the direction sensor unit operates intermittently in order to detect seedlings planted at regular intervals.
If the actuator of the direction sensor is made relatively long, a relatively long detection signal can be obtained.
On the other hand, since the steering control using the hydraulic cylinder is a relatively quick operation, there is no problem in controlling the direction during the detection signal generation period described above. Furthermore, a small resistor 42 provided in the servo unit 37 creates a somewhat inactive region by giving a slight difference in the signals supplied to the comparators 43 and 44, thereby allowing some play in direction control. It is for providing parts.

[Effects of the Invention] As explained above, the steering control device for a mobile agricultural machine according to the present invention is provided with a switching valve that frees the input and output oil passages of the hydraulic cylinder provided for steering drive only during manual control. Since the vehicle is configured to pass the automatic direction control circuit during automatic direction control, it has the excellent effect of extremely stabilizing straight-line performance during automatic control even with the manual priority function.

[Brief explanation of the drawing]

1 to 3 are a side view, a front view, a plan view, and a fourth embodiment of a rice transplanter to which the present invention is applied.
5 is a plan view showing the steering portion, FIG. 5 is a connection diagram showing the hydraulic system, and FIG. 6 is a circuit diagram showing the control circuit. DESCRIPTION OF SYMBOLS 1... automatic rice transplanter, 2... front wheel, 3... rear wheel, 4... float, 5... planting device, 6... planting claw, 7... seedling stand, 8a, 8b... cylinder, 9a, 9b... direction sensor unit, 10...Planting row, 11a, 11b
...Float, 12, 13... Direction sensor, 14... Cylinder, 14a... Potentiometer, 15... Handle, 16... Pressure regulating valve, 17... Constant pressure hydraulic source, 1
8, 19, 20, 25...Solenoid valve, 21, 22, 2
3, 24, 26...Solenoid, 27a, 27b...
Sensor unit vertical movement switch, 28a, 28b
...Limit switch, 29a, 29b...Steering switch, 30...Relay, 31...Manual control circuit, 32a, 32b...Diode, 33...
Left turn signal terminal, 34... Right turn signal terminal, 35... Straight ahead signal terminal, 36... Noah gate, 37... Servo unit, 38-40... Transistor, 41a-41
c...Resistance, 42...Small resistance, 43, 44...Comparator, P...Hydraulic pump.

Claims (1)

[Scope of Claims] 1. A steering device connected to a manually operated steering wheel, and a hydraulic cylinder for automatic direction control connected to the steering device, wherein manual direction control by the steering wheel and automatic direction control by the hydraulic cylinder are provided. In a mobile agricultural machine configured to stabilize the straight line by closing the input and output oil passages of the hydraulic cylinder when moving straight through automatic direction control, A switching valve is provided in the hydraulic cylinder, which is operated by manual direction control using a handle, and connects the input and output oil passages to free the hydraulic cylinder, so that the automatic direction control circuit passes during manual direction control. Characteristic steering control device for mobile agricultural machinery.