JPS5829386B2 - Gray Dano Bra - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic grader blade control device that reduces the load by variably controlling the cutting angle of the blade when the load applied to the grader blade increases beyond a certain level.

The blade cutting angle of the motor grader is fixed at a predetermined angle depending on the work content before the work is started.

That is, as shown in FIG.
, a blade tilt ring 4 via a shaft 2, a locking portion 1b, and an arm 7 via a shaft 3.
It is attached to the arm 7 via.

Before the work, the tilt ring 4 is moved to a predetermined position and fixed according to the work content, and the cutting angle θ of the blade 1 with respect to the ground is set.

This excavation angle θ is not varied during the work.

Therefore, when the vehicle is traveling while using the blade during civil engineering work or snow removal work, if the load applied to the blade is too large, the engine may stall or slip, making the vehicle unable to travel.

In order to avoid this, the load is reduced by raising or rotating the blade, but conventionally all such blade control has been done manually, and therefore, it is difficult to release the blade handle while driving. This is extremely dangerous and reduces work efficiency.

Furthermore, when the blade is moved upward, a step is created by that amount,
Further, when the blade is rotated, the working width becomes shorter and the working efficiency decreases.

The present invention has been made in view of the above points, and a hydraulic cylinder is provided in place of the blade tilt ring described above, and on the other hand,
To detect overload and slip, the engine speed and throttle lever opening are compared to obtain an overload signal, and the engine speed and idle wheel speed are compared to obtain a slip signal. To provide an automatic blade control device for a grader, which reduces the load by controlling the hydraulic cylinder based on any of the signals to change the blade cutting angle, and returns to the original cutting angle after the load is reduced. It is something.

Hereinafter, the present invention will be explained in detail based on one embodiment of the accompanying drawings.

In FIG. 2, a blade 1 of a motor grader (not shown) has a locking portion 1a connected to a rod 8a of a hydraulic cylinder 8 via a joint 9, and a locking portion 1b connected to an arm 7 via a shaft 3. It is pivoted on.

The hydraulic cylinder 8 is attached to the arm 7 via a locking portion 8b, and is connected via pipes 30, 31 to a direction switching solenoid valve (hereinafter simply referred to as a solenoid valve) 10.

Therefore, this electromagnetic valve 10 is controlled to switch so that the hydraulic cylinder 8
By expanding and contracting the blade 1, the blade 1 can be tilted and rotated, and the cutting angle θ of the blade 1 relative to the ground can be variably controlled to an appropriate angle.

By changing the cutting angle of the blade 1, the load applied to the blade 1 can be changed.

The engine rotation speed detector 11 detects the rotation speed N of a driving engine (not shown) mounted on the motor grader and outputs a corresponding signal e1, which is applied to the arithmetic circuit 14.15.

The throttle lever opening degree detector 12 detects the opening degree α of the throttle lever (not shown) of the engine, outputs a corresponding signal e2, and applies the signal e2 to the arithmetic circuit 14.

The idle wheel rotation speed detector 13 detects the front wheels (
(not shown) is detected and a corresponding signal e3 is output and applied to the arithmetic circuit 15.

Now, opening the throttle lever by the opening α determines the engine speed N under no load, but as the load increases, the engine speed N decreases.Therefore, the calculation circuit 14 calculates these N and α. If the signal e4 is obtained by calculating the ratio N/a, that is, the ratio e1/e2 of the signals el and e2, this signal can be used as a load signal.

This signal e4 is applied to the comparison circuit 16.

The comparison circuit 16 compares this signal e4 with the reference value E1, and when e4<El, it determines that there is an overload and outputs an overload signal e6==1 (/% A signal), e,
>E, outputs e6=0 (low signal).

This overload signal e6 is applied to the OR circuit 18.

On the other hand, when an overload occurs and the engine speed does not decrease as described above and the drive wheels (not shown) simply slip, the overload cannot be detected using the above-described detection method alone.

However, when the drive wheels slip due to overload, their rotational speed increases more than the rotational speed of the front wheels (idling wheels).

Therefore, the calculation circuit 15 calculates the ratio n/N between the front wheel rotation speed n and the drive wheel rotation speed, that is, the engine rotation speed N, that is, the ratio e3/e1 between the signals e3 and el, and calculates the ratio according to the calculated value. Once the signal e is obtained, this signal e5 can be used as a slip signal.

In this case, the engine rotation speed N is directly used as the rotation speed of the drive wheels, but if a transmission is used (which is the case in most cases), an appropriate coefficient cn according to the gear ratio may be used.
is used by multiplying the above value N, but in this example, for convenience of explanation, the value N is used as is as described above.

Furthermore, in each of the above calculations, the "ratio" of both signals is determined, but the "difference" may also be determined.

The output signal e from this arithmetic circuit 15 is applied to a comparison circuit 17.

The comparator 17 compares the signal e and the reference value E2, and when e and E2 are reached, it is determined that the drive wheel is slipping due to overload, and a slip signal e7=1 is outputted and added to the OR circuit 18.

Of course, when there is no slip, the signal e7=0.

The OR circuit 18 receives the overload signal e6 and the slip signal e7.
The open signal e8-1, which is also applied to either one, is output and applied to the pulse generator 20 and the knot circuit 23.

When the signal e8 is applied, the pulse generator 20 outputs a pulse signal P1 (FIG. 3b), which is applied to the counter 21 and the solenoid 10Sb of the solenoid valve 10, as well as to the solenoid 1.
0Sb is energized.

The pulse width variable device 19 is for setting the pulse @T1 of the pulse signal P0 outputted by the pulse generator 20 to an appropriate width.

That is, depending on whether the target to be worked by the blade 1 is soil, sand, gravel, etc., the one-time cutting control angle θ of the blade 1 by one pulse signal P1, which will be described later, is set to an optimal value. .

Note that this pulse width T0, that is, the cutting control angle θ1 is determined in advance based on experiments and the like.

The counter 21 sequentially counts the number of pulses of the pulse signal P1 output from the pulse generator 20, and outputs the count c1.
is added to the comparator 22.

When the output e8 of the OR circuit 18 is O, the NOT circuit 23 outputs a signal el2l and applies it to the pulse generator 25 and the AND circuit 29.

Similarly to the pulse generator 20, the pulse generator 25 outputs the pulse signal P2 while the signal e is being applied, and applies it to the gate circuits 26 and 27.

The pulse width variable device 24 sets the pulse width T2 of the pulse signal P2 outputted by the pulse generator 25 to an appropriate width.

That is, in a hydraulic system, since the flow rate varies slightly depending on the direction in which pressure oil is produced, the switching time of the electromagnetic valve 10 is changed to correct the stroke error due to the direction in which the hydraulic cylinder 8 moves.

The counter 28 sequentially counts the number of pulses of the pulse signal P2 applied via the gate circuit 27 and applies the counting output to the comparator 22.

Comparator 22 compares input signals c1 and c2, c 1
> c 2, the signal c3=1 is output and added to the AND circuit 29, and when e 1 "" e 2, the signal c3 becomes O, and at the same time, the reset signal R is output and input to the counters 21 and 28. In addition, the counters 21 and 28 are reset.

The AND circuit 29 outputs the gate signal g=l when the input signals eg and c3 are both 1, and the gate circuits 26 and 27
In addition, the gate circuits 26 and 27 are opened.

Therefore, the pulse signal P2 is applied to the solenoid 108a of the solenoid valve 10 via this gate circuit 26, and this solenoid 10Sa is energized for a time T2 (pulse width of pulse P2).

The solenoid valve 10 is switched to positions 10A and 10B, respectively, when solenoids 10Sa and 10Sb are energized, and to intermediate position 10C when neither solenoid is energized.

Now, it is assumed that a ground leveling operation is performed by setting the blade 1 at a cutting angle θ1 with respect to the ground (FIG. 2).

In this state where the blade 1 is initially set, both counters 21 and 28 are reset by the reset signal R of the comparator 22.

When the load applied to the blade 1 is small during work and neither the overload signal e6 nor the slip signal e7 is output, the output e8 of the OR circuit 18 is O, and therefore the pulse signal P1 is not output and the solenoid 1
0Sb is not activated.

Further, the output e of the NOT circuit 23 becomes 1, and a pulse signal P2 is outputted and applied to the gate circuits 26 and 27.

On the other hand, as described above, the comparator 22 outputs the signal c3=1 only when el>e2, and the signal c3 is O in the above-mentioned state where C2=0.

Therefore, the gate signal g of the AND circuit 29 is O, and both gate circuits 26 and 27 are closed.

Therefore, the solenoid 108a is also not energized, the solenoid valve 10 remains switched to the intermediate amount 10c, and the blade 1 is held at said initial cutting angle θ1.

Suppose that the load applied to the blade 1 increases and, for example, the comparator circuit 16 outputs an overload signal e6 at time t1.

The OR circuit 18 outputs a signal e8=1 (FIG. 3a) and applies it to the pulse generator 20.

When the pulse generator 20 receives the signal e8, it outputs a pulse signal P1 (b in the figure) to energize the solenoid 10Sb of the solenoid valve 10 for a time T1.

The solenoid valve 10 is switched to the open position 10B at this time T1 to extend the hydraulic cylinder 8 and tilt and rotate the blade 1 counterclockwise by an angle θ1.

Therefore, the cutting angle of blade 1 decreases by θ1 and θ=θ
-θ (C in the same figure), and the load applied to the blade 1 is reduced in accordance with the decrease in the cutting angle.

In this manner, while the pulse signal P1 is being generated, the blade 1 is sequentially rotated counterclockwise by the angle θ1, and the cutting angle θ is sequentially decreased to reduce the load applied to the blade 1.

At the same time, the number of pulses P applied to the blade 1 is counted by a counter 21, and the counting output c1 is sequentially applied to a comparator 22.

Then, for example, the pulse signal P1m for the door is used at the time t.
Suppose that when the cutting angle of the blade 1 becomes θ2θ1−mθ1 at m, the load applied to the blade 1 becomes small and the overload signal e6 becomes O.

The pulse generator 20 immediately stops outputting the pulse signal P1, so that the solenoid valve 10 is switched to and held at the intermediate quantity 10c.

Therefore, the blade 1 is stopped at the cutting angle θ=θ1−door θ1.

The counting output of the ring 21 at this time is 01 m, and the position of the blade 1 is shown by a chain line (FIG. 2).

When the output signal e8 of the OR circuit 18 becomes O, the NOT circuit 23 outputs the signal e,=1 (FIG. 3d), so the pulse generator 25 immediately outputs the pulse signal P2 and the gate circuit 26.27 (e).

On the other hand, since the content of the counter 28 is O, its count output c2 is O. Therefore, the outputs of both counters 21 and 28 are in the relationship c 1 m > c 2 -= 0, and the comparator 22 outputs the signal c3 =1 is output.

Furthermore, since the output e of the NOT circuit 23 is 1, the AND circuit 29 outputs the gate signal g=1, opening the gate circuits 26 and 27.

Therefore, the pulse signal P2 is applied to the solenoid 108a of the electromagnetic valve 10 via the gate circuit 26, and the pulse signal P2 is applied to the solenoid 108a of the electromagnetic valve 10.
Sa is energized for a time T2 (T2 is the pulse width of pulse P2).

The solenoid valve 10 is switched to the open position 10A at this time T2, shortening the hydraulic cylinder 8 and moving the blade 1 at an angle θ.
Rotate 1 turn clockwise.

Therefore, the cutting angle of the blade 1 increases by .theta. (FIG. 3e), and the load applied to the blade 1 increases in accordance with this increase .theta.1.

In this way, while the pulse signal P2 is being generated, the blade 1 is sequentially tilted clockwise by an angle θ1,
The load on the blade 1 is always maximized by increasing the cutting angle θ sequentially.

Then, at time tn when the pulse P2m for the door is output, when the count output c2m of the counter 28 becomes equal to the count output c1rrL of the counter 21, the comparator 22
The output signal c3 becomes 0, and at the same time the reset signal R=1
Output.

Therefore, the gate signal gb'-o of the AND circuit 29 is obtained, and the gate circuits 26 and 27 are closed.

Therefore, the pulse signal P2 is no longer applied to the solenoid 108a of the solenoid valve 10, and the solenoid valve 10 is in the middle position 10.
c, and the blade 1 is stopped and held at that position.

Further, the counters 21 and 2B are each reset by a reset signal R.

In this state, the cutting angle θ of the blade 1 is θ=θ1−
mθ1+door θ1=θ1, and the blade is returned to the initial setting angle.

As described above, when the load increases while the cutting angle of the blade 1 is being sequentially increased by θ1 and the signal e8=1 is output again from the OR circuit 18, the pulse signal P1 is immediately outputted and the pulse signal P1 is outputted as described above. Decrease the cutting angle as follows.

Then, as soon as the signal e8 from the OR circuit 18 becomes 0, the blade control is performed to increase the cutting angle again.

Finally, the cutting angle θ is set to the initial setting angle θ1.

Thus, the cutting angle can be appropriately controlled depending on the load condition of the blade 1.

As explained above, according to the present invention, the cutting angle of the blade is controlled according to the load, so there is no difference in level on the leveled surface, and the pushing width of the blade is constant, which improves work efficiency. will not decrease.

Further, since the blade control is performed automatically, the operator can concentrate only on the travel control, which is safe, and has excellent effects such as not requiring advanced maneuvering skills.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional grader blade mounting structure, FIG. 2 is a diagram showing an embodiment of a grader blade automatic control device according to the present invention, and FIGS. 3 a to 3 e are parts of FIG. 2. It is a graph showing the control state of the output signal and the cutting angle of the blade. DESCRIPTION OF SYMBOLS 1...Blade, 7...Arm, 8...Hydraulic cylinder, 9...Joint, 10...Solenoid valve, 11...Engine speed detector, 12...Throttle lever opening degree Detector, 13... Idle wheel rotation speed detector, 14.15.
... Arithmetic circuit, 16, 17, 22... Comparator, 18.
... OR circuit, 19.24 ... Pulse width variable device, 20
, 25... Pulse generator, 21.28... Counter, 23... Not circuit, 26.27... Gate circuit, 29... AND circuit.

Claims (1)

[Claims] 1 means for detecting an overload state of the blade; a cylinder disposed between the blade and the blade support arm that varies the cutting angle of the blade according to expansion and contraction; a switching solenoid valve for controlling the cylinder; and a switching solenoid valve for controlling the cylinder when overloaded. means for changing the cutting angle of the blade to a set angle or less by switching a solenoid valve to extend the cylinder; and controlling the switching solenoid valve only when an overload condition is not detected and the blade cutting angle is equal to or less than the set angle. and a means for shortening the cylinder and returning the changed cutting angle to the original value, reducing the cutting angle when the blade is overloaded to reduce the load, and gradually reducing the cutting angle when the blade is under overload. A grader blade automatic control device that returns the angle below the set angle.