JPS586816B2 - Bulldozer blade automatic control device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an automatic blade control device for a pull dozer.

The automatic blade control method involves emitting a laser beam from a laser projector placed at a predetermined position as a reference height, and detecting the received laser beam by a receiver fixed at a predetermined position on the vehicle's blade, etc. A method of automatically controlling the height of the blade based on the signal obtained by obtaining a height signal, or an inclination angle signal of the C frame with respect to a horizontal reference plane from an inclinometer placed at a predetermined position of the C frame of the blade. There is a method of automatically controlling the height of the blade based on the deviation between the C frame and the preset angle of the C frame.

The hydraulic circuits used in these control systems are constructed by inserting and connecting ON-OFF switching valves, servo valves, etc. to the hydraulic circuits installed in the vehicle.

However, configuring a hydraulic circuit in this manner requires a large-capacity valve, and has the drawbacks that modification, installation, etc. are extremely troublesome.

The present invention has been made for the purpose of eliminating the above-mentioned drawbacks, and the manual operation valve is switched and controlled by a slave cylinder, and this slave cylinder is driven by a pulse signal having a pulse width according to the deviation, thereby opening the manual operation valve. The present invention provides an automatic blade control device for a pull dozer that controls the flow rate by adjusting the area and obtains control characteristics similar to those of a proportional control valve using only an ON-OFF switching valve.

The present invention will be described in detail below based on an embodiment of the accompanying drawings.

In FIG. 1, the blade 3 is attached to the tip of a C frame 2 whose one end is rotatably supported on the car body 1 of the pull dozer, and is disposed between the car body 1 and the C frame 2. The vertical movement is controlled by a pair of lift cylinders 4.

The manual operation valve 5 controls the lift cylinder 4 to be extended (position 5▲), retracted (position 5B), held (position 5C), floated (position 5D), etc. according to the switching positions 5A to 5D. The cylinder section 6 of the operating cylinder (hereinafter referred to as slave cylinder) 6 is connected via the rod 6a.
The piston rod 6c of the slave cylinder 6 is connected to a manual operation lever 7 for raising and lowering the blade.

The locking mechanism 8 is for locking the operating lever 7 during automatic blade control.

As will be described later, this locking mechanism 8 is interlocked with a switch 28 for switching between manual and automatic blade control, and the operating lever 7
When the switch 28 is locked, the switch 28 is turned on, and when the lock is released, the switch 28 is turned off.

The first solenoid valve 9 and the second solenoid valve 10 are for driving and controlling the slave cylinder 6.
and the hydraulic pump P2, and switching is controlled based on the output signals E6 to E7 of the comparator 25.

When the blade is manually controlled, the neutral positions 9C and 1 are set, respectively.
The slave cylinder 6 is switched to 0A and the manual operation valve 5
The operating lever 7 and the rod 6a are fixed by hydraulically locking at a stroke position corresponding to the neutral position 5C.

Therefore, the operator operates the manual operation valve 5 by using the operation lever 7.
can be manually controlled to a predetermined switching position.

Further, during automatic control, the operating lever 7 is locked by the locking mechanism 8, and therefore, the first solenoid valve 9 telescopically drives the cylinder portion 6b of the slave cylinder 6 relative to the piston rod 6C in accordance with the switching positions 9A and 9B. to control the manually operated valve 5 to a predetermined switching position.

The second solenoid valve 10 is for assisting the manually operated valve 5 to return automatically by the return force of the spring 5E.
When switched to position 10B, the bottom side and head side chambers are directly connected to the tank T3, allowing the slave cylinder 6 to move freely.

The vehicle body inclination angle detector 11 is for detecting the inclination angle of the vehicle body 1 with respect to a reference horizontal plane, and is installed at approximately the center of gravity of the pulldozer vehicle body 1, and outputs a tilt detection signal e1 according to the inclination angle of the vehicle body 1. It is added to the first arithmetic unit 13.

Since the vehicle body inclination angle detector 11 is installed approximately at the center of gravity of the vehicle body 1, it is possible to accurately detect the inclination angle of the vehicle body 1 without being affected by rotational moment due to the inclination of the vehicle body 10 in the longitudinal direction. .

The cylinder stroke detector 12 is installed in parallel with the blade lift cylinder 4, detects the stroke of the cylinder 4, and outputs a cylinder stroke detection signal e2 to the ratio calculator 1.
Add to 3.

The computing unit 13 is provided with vehicle body inclination angle data by the inclination detection signal e1, and lift cylinder stroke data by the stroke detection signal e2.

Therefore, the computing unit 13 calculates the blade 3 from the horizontal reference plane.
A blade height signal eh corresponding to the height (inclination of the C frame) is output.

The blade height setter 16 is used to preset the height of the blade 3 with respect to the horizontal reference plane, and outputs a blade height setting signal EH (Fig. 2a) according to the setting and performs the second calculation. Add to bowl 14.

The calculator 14 calculates the deviation E between the height setting signal EH and the signal eh.

The slave cylinder 6 is driven in accordance with this deviation E1, the valve 5 is switched, and the lift cylinder 4 is appropriately driven.

Then, the deviation E is 01, that is, the current height of the blade 3 eh
is automatically controlled to match the set height.

The throttle lever opening degree detector 17 detects the throttle opening degree of a throttle lever (not shown) that controls the rotation speed of the driving engine (not shown) of the bulldozer, and detects the throttle opening degree according to the throttle opening degree. The signal e4 is output and applied to the arithmetic circuit 19.

The engine rotational speed detector 18 detects the rotational speed of the driving engine, outputs an engine rotational speed signal e corresponding to the rotational speed, and applies it to the arithmetic circuit 19.

The calculation circuit 19 calculates the load pressure (wheel slip) applied to the blade 3 based on the throttle opening signal e4 and the engine speed signal e, and generates a blade load (slip) signal e6 corresponding to the load pressure (slip). Output and comparator 21
Add to.

The load setting device 20 is for setting the maximum load pressure that can be applied to the blade 3 of the bulldozer depending on the working conditions,
A load setting signal e7 corresponding to the set value is output and applied to the comparator 21.

The comparator 21 receives the blade load signal e6 and the load setting signal e.
7, when the signal e6 exceeds the signal e7, that is, when the blade 3 is overloaded, the overload signal e
8 is output and added to the arithmetic unit 14.

The computing unit 14 normally outputs the deviation E1 (FIG. 2b) between the blade height setting signal E0 and the blade height feedback signal eh, and outputs the deviation E1 (FIG. 2b) between the blade height setting signal E0 and the blade height feedback signal eh, and
Add to 3.

The pulse width control circuit 23 outputs a pulse signal P (FIG. 2C) with a pulse width proportional to the magnitude of the deviation signal E1 at predetermined time intervals T and applies it to the gate circuit 22, and during this pulse width Gate circuit 22 is opened.

Therefore, while the pulse signal P is being applied, the gate circuit 22 outputs the deviation signal E2 (FIG. 2d) and applies it to the arithmetic unit 24.

Further, when the overload signal e8 is applied due to an overload of the blade, the computing unit 14 cancels the feedback control of the blade and sends a signal to the gate circuit 22 and pulse control circuit 23 to command the blade to rise until the overload signal e8 disappears. Add to.

The spool position detector 15 continuously detects the transition position of the rod 6a of the slave cylinder 6.
The spool position of the manually operated valve 5 connected to a is detected, and a spool position detection signal e3 is output and added to the calculator 24.

The arithmetic unit 24 outputs a signal E3 corresponding to the deviation between the signal E2 and the signal e3, and applies it to the comparator 25.

The comparator 25 compares the deviation signal E3 and the dead band width setting value signal E4 set by the dead band width setting device 26,
> When IE,l, the control signal E, for raising and lowering the blade.
, E6 to output the solenoid 9Sa of the solenoid valve 9,
Add to 9Sb.

The pulse generator 21 outputs a signal E with a predetermined pulse width when the control signals E5 and E6 are both O, that is, when the manual operation valve 5 is in the neutral position and there is no need to raise or lower the blade 3. Solenoid 1 of solenoid valve 10
08 and switches the solenoid valve 10 to position 10B.

As a result, the slave cylinder 6 becomes free, and the return spring 5E of the manually operated valve 5 quickly switches the valve 5 to the neutral position 5C.

The changeover switch 28 is for switching the control of the blade 3 between manual and automatic control, and is linked to the locking mechanism 8, and is turned on when the manual operation lever 1 is locked.
The control signals E, jE, E7 can now be supplied to each electromagnetic valve switching solenoid.

As a result, the blade 3 is set to a state where automatic control is possible.

When the blade 3 is maintained at a predetermined height corresponding to the set value EI{ shown in FIG. 2a, the manually operated valve 5 is switched to the neutral position 5C.

Suppose now that the vehicle body 1 is tilted significantly while leveling the ground with the blade 3 being controlled and held at the predetermined height.

The calculator 14 calculates the blade height signal and the set value E at this time.
A deviation signal E1 from H is outputted, and is outputted as a signal E2 (FIG. 2d) via the gate circuit 22.

The computing unit 24 outputs a deviation signal E3 between this signal E2 and the spool position signal e3, and the comparator 25 outputs, for example, a blade elevation signal E5.

When this signal E is applied, the solenoid valve 9 is switched to position 9B and drives the scrape cylinder 6 in the direction of arrow A.

Therefore, the manually operated valve 5 is switched to position 5B.

The signal e3 increases in accordance with the shift of the slave cylinder 6, and when the deviation signal E3 becomes less than the dead band width setting value E4,
The signal E becomes O, and the solenoid valve 9 is switched to the neutral position 9C.

At the same time, signal E7 is output and solenoid valve 10 is switched to position 10B.

Therefore, the slave cylinder 6 can move freely.

Therefore, the slave cylinder 6 is gradually driven toward the neutral position 5C in response to the signal E2, that is, so that the deviation signal E3 is maintained at O as shown in FIG. 2e.

Therefore, the output flow rate of the manually operated valve 5 corresponds to the movement of the slave cylinder 6 as shown in FIG. 2f, and the blade 3 is moved upward as shown in FIG. Ru.

Then, after the predetermined time T, the slave cylinder 6 is driven again in response to the signal E2 in the same manner as described above, and the manually operated valve 5 is controlled.

In this way, the blade 3 is sequentially controlled to move upward until the deviation signal E3 becomes equal to or less than the dead band width setting signal E4.

Now, the amount of movement of the slave cylinder 6 in the direction of arrow A corresponds to the magnitude of the deviation signal E3, and therefore, the opening area of the manually operated valve 5 at position 5B is controlled in accordance with this signal E3.

That is, when the signal E3 is large, the manually operated valve 5 is completely switched to the position 5B, and the opening area is maximized, and as the signal E becomes smaller, the opening area is reduced to a half-throttle state 9, and the output is reduced. Flow rate decreases.

Therefore, the output flow rate can be controlled according to the deviation signal, and the manually operated valve 5 can be given characteristics similar to those of a proportional control valve.

Similarly, when the blade lowering control signal E5 is output, the rod 6a of the slave cylinder 6 is driven in the direction of arrow A, and the manual operation valve 5 is switched to the position 5A.

Further, when an overload of the blade 3 is detected, the deviation data between the signals EH and eh is blocked by the signal e8, and a control signal E for forcibly commanding the blade to rise is output.

As explained above, according to the present invention, by controlling the flow rate by adjusting the opening area of the manually operated valve with the slave cylinder, it is possible to obtain characteristics close to those of a proportional control valve with only an on-off switching valve, which is stable and Accurate positioning control can be performed.

Moreover, it has excellent effects such as being able to be easily attached to a conventional device and constructing a control device at low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic blade control device for a bulldozer according to the present invention, and FIG. 2 is a timing chart showing an example of the operation of FIG. 3...Blade, 4...Lift cylinder, 5...
Directional switching valve, 6...Slave cylinder, 7...Manual operation lever, 8...Lock mechanism, 9.10...Solenoid valve, 11...Vehicle body inclination angle detector, 12...Cylinder Stroke detector, 13, 14, 24... Arithmetic unit, 1
5... Spool position detector, 16... Blade height setting device, 17... Throttle opening detector, 18...
Engine speed detector, 20...Load setting device, 22.
. . . gate circuit, 23 . . . pulse width control circuit, 21.
25... Comparator, 26... Dead band width setting device, 27.
...Pulse generator, 28...Manual-automatic changeover switch.

Claims (1)

[Claims] 1. A pulse width control circuit that outputs a pulse signal with a pulse width corresponding to a deviation signal between the preset blade height value and the current blade height, and a gate circuit that outputs the deviation signal while this pulse signal is being applied. a slave cylinder that is connected between the manual operation lever and the manual operation valve and is fixed during manual operation, and is controlled to expand and contract as appropriate during automatic operation to switch the manual operation valve to a predetermined spool position; and the position of the slave cylinder. a spool position detector that detects and outputs a corresponding position signal; a comparator that outputs a blade control signal when the deviation value between the position signal and the deviation signal exceeds a preset dead band width; and a solenoid valve that is switched and controlled based on the deviation and drives the slave cylinder, and controls the blade by driving the slave cylinder according to the deviation, adjusting the opening area of the manually operated valve, and controlling the output flow rate. Automatic pull dozer blade control device.