JPS5849658B2 - Gray Dano Blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic grader blade control device that automatically clamps the blade to reduce the load when the load applied to the grader flade becomes greater than a certain level.

When performing earthwork work or snow removal work using a motor grader, if the load applied to the blade is too large, the engine stalls or slips, making it impossible to drive.

To avoid this, the blades must be rotated or raised, but generally such blade restraints are done manually, and therefore, when performing the above-mentioned restraints while driving, it is necessary to Removing the handle: It is very dangerous as you have to take your hands off the handle, and it also reduces work efficiency.

Conventionally, the method of automatically controlling the blades in the above-mentioned case is to detect the ratio or difference between the rotation speeds of the front wheels and the rear wheels, and to control the blades when this detected value becomes smaller or larger than a reference value. There is a method of raising the blade automatically, or a method of raising the blade by determining an increase in load based on a decrease in the engine speed or a rotation speed ratio of the input/output shaft of the torque converter.

However, in the former case, the load can only be detected when the drive wheels slip, so if the engine stalls without slipping, the blade control 2 described above cannot be performed. Moreover, in the latter case, the load cannot be detected if the drive wheel slips, contrary to the above.Furthermore, each of the methods described above detects the load only by raising the blade. There are drawbacks such as steps being created on the finished surface in order to reduce the amount of water.

The present invention was made for the purpose of eliminating the above-mentioned drawbacks.
An overload signal is obtained by comparing the engine speed and the opening degree of the throttle lever, and a slip signal is obtained by comparing the engine speed and the free wheel speed. Even if the signal is detected, the load is reduced by sequentially rotating the blade by a predetermined angle in the direction of increasing the propulsion angle, and then the rotation angle becomes a constant angle. The grader is designed to reduce the load by sequentially raising the blades by a predetermined height while the signal is detected and the above signal is detected. A blade automatic control device is provided.

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

In FIG. 1, an engine rotation speed detector 1 detects the rotation speed N of a driving engine (not shown) mounted on the grader (not shown), and sends a signal corresponding to the rotation speed N. e1
is output and added to arithmetic circuits 4 and 5.

The throttle lever opening degree detector 2 detects the opening degree of a throttle lever (not shown) of the engine, outputs a signal e2 corresponding to the opening degree, and applies the signal e2 to the arithmetic circuit 4.

The idle wheel (in this case, the front wheel) rotation speed detector 3 outputs a signal e3 corresponding to the rotation speed of the front wheel (not shown) and adds it to the arithmetic circuit 5.

Opening a throttle lever (not shown) by a certain opening degree α determines the engine rotational speed N in the case of no load, but as the load increases, the rotational speed N decreases.

Therefore, the arithmetic circuit 4 calculates the ratio N4 of N and α, that is, the ratio e of the human power signals e1 and e2! /e2 is calculated, and a signal e4 corresponding to the calculated value is output and added to the comparator circuit 6.

The comparator circuit 6 compares this signal e4 with a reference value E1, and when e 4 <E I, it determines that there is an overload, and outputs an overload signal e6 to be added to the OR circuit 8.

On the other hand, if the overload causes the drive wheels (not shown) to slip without causing the engine to stall as described above, the overload cannot be detected using only the above method.

However, when a drive wheel (not shown) slips due to overload, the rotation speed of the drive wheel increases more than the rotation speed of the front wheel (idling wheel).

Therefore, the calculation circuit 5 calculates the ratio n/N between the rotation speed n of the front wheels and the rotation speed N of the drive wheels, that is, the engine rotation speed N, that is, the ratio e3/e1 between the signals e3 and 01,
A signal e5 corresponding to the calculated value is output and applied to the comparison circuit 7.

The comparator circuit 7 compares this input signal e5 with a reference value E2, and if e5<E2, it is determined that the driving wheel slips due to overload, and outputs a slip signal e7, which is added to the OR circuit 8.

In addition, in the above calculation, find the "ratio" of the input signal and L
・Even if you look for the “difference” L・.

The OR circuit 8 receives either the overload signal e5 or the slip signal e7 and outputs the L/L signal eg (FIG. 4a), which is applied to the gate circuits 9 and 17.

In this case, the engine rotation speed N was used directly as the rotation speed of the driving wheels, but if a transmission is available, the above value N may be multiplied by an appropriate coefficient Cn depending on the transmission ratio. Needless to say, for convenience of explanation, the value N is used as is as described above.

The flade 23 is fixed to a circular plate 22, and the circular plate 22 is connected to the rods 25a, 26 of the lift cylinders 25, 26.
They are each fixedly installed at ℃・ru.

The hydraulic motor 21 is connected to the annular plate 22 via a gear system (not shown), and moves the annular plate 22 counterclockwise or counterclockwise based on hydraulic oil supplied from pipes 31 and 32. rotate it clockwise.

Further, the lift cylinders 25 and 26 move the annular plate 22 upward based on hydraulic oil supplied through the pipe 33.

Therefore, the blade 23 is controlled to rotate counterclockwise and clockwise and to move upward by the hydraulic motor 21 and cylinders 25 and 26.

The blade rotation direction detector 12 is, for example, a rotary potentiometer coupled to the annular plate 22 via a gear system (not shown), and is connected to the annular plate 22, that is, the blade 230.
A signal ev corresponding to the rotation direction and rotation angle is output and applied to comparison circuits 13 and 14.

In this rotary potentiometer 12, for example, as shown in FIG.
d is driven by the annular plate 22 via the gear system, slides on the resistor portion 12a, and outputs the signal ev via the connection terminal 12e.

That is, the blade 23 is perpendicular to the direction of movement of the grader (as shown in FIG. 2, the rotation angle θ1 of the blade 23 is O).
), it outputs 0, and when the blade 23 rotates counterclockwise or clockwise, it outputs blade rotation signals 1 ey and ey of polarity and magnitude according to the rotation direction and rotation angle θ.

Comparison circuit 13 outputs signal C1 when input signal ev is +ev, and outputs signal C2 when input signal ev is 1ev, and adds them to AND15 and 16, respectively.

The comparison circuit 14 compares the absolute value lev l of the input signal ey with a reference value E3, and outputs a gate signal g1 when lev l <E3, and outputs a gate signal g2 when lev l >E3. , these gate signals g1,
g2 is applied to the gate circuits 9, 17 to open the gate circuits 9, 17.

This reference value E3 is a signal corresponding to the maximum rotation angle θMAX of the hood 23 in the counterclockwise and clockwise directions, which is 60°.

The reason why the maximum rotation angle θ of the blade 23 is limited to a certain angle is that if the rotation angle is increased, the load applied to the blade 23 can be correspondingly reduced, but the push-up width of the blade 23 is As a result, the work efficiency actually decreases.

Therefore, the rotation angle of the blade 230 is limited to a certain angle or less,
Even if the rotation is controlled to this maximum rotation angle, the blade 23
In cases where the load applied to L can be reduced, Flede 23
The load is reduced by moving the motor upward.

Of course, it goes without saying that the maximum rotation angle θ is set to an optimum value based on the length of the blade 23, etc. , the signal e8 is added to output a pulse signal P1 (FIG. 4C) between L and R, and each of the AND circuits 15, 1
Add to 6.

The pulse width variable device 10 is for setting the pulse width T1 of the pulse signal P1 outputted from the pulse generator 11 to an appropriate width.

That is, depending on whether the target of work is soil, sand, gravel, etc., the control rotation angle θ1 of the blade 2301 times by one pulse signal P1, which will be described later, is set to an optimal value.

Note that this rotation angle θ. is determined in advance based on experiments and the like.

When the AND condition is satisfied, the AND circuits 15 and 16 output signals S1 and S2, respectively, and energize the solenoids 20Sa and 20Sb of the direction switching solenoid valve (hereinafter simply referred to as solenoid valve) 20, respectively.

When the solenoids 20Sa and 20Sb are energized, the solenoid valve 20 is switched to positions 20A and 20B, respectively, and the L-shift solenoids 20Sa and 20Sb are also not energized (and sometimes switched to the middle position 20c).

Then, when the solenoid valve 20 is switched to positions 20A and 20B, the hydraulic motor 21 moves the circular plate 22 counterclockwise.
Rotation control clockwise.

When the signal e8 is applied via the gate circuit 17, the pulse generator 19 outputs a pulse signal P2 (FIG. 4f) while the signal e8 is applied, and operates as a switching solenoid valve (hereinafter simply referred to as a solenoid valve). Activate the solenoid 24S of L/U) 24.

The solenoid valve 24 is in position 2 when the solenoid 24S is energized.
When switched to 4A and not energized, it is set to the middle position 24.
Switched to B.

Then, when the solenoid valve 24 is switched to position 24A,
The lift cylinders 25, 26 are shortened to control the annular plate 22 upwardly.

The pulse width variable device 18 is for setting the pulse width T2 of the pulse signal P2 outputted from the pulse generator 19 to an appropriate value.

That is, similar to the pulse width variable device 10 described above, the one-time blade lifting amount hr by the one pulse signal P2 is set to the optimum value depending on the work object, and is determined in advance based on experiments etc. do.

Now, the blade 23 is set counterclockwise with respect to the traveling direction of the grader at a predetermined rotation angle θ1 (Fig. 2), and the lower end 23a of the blade is in contact with the ground 30 (Fig. 1), and the ground is leveled. Assume that the work is performed and L.

In this state, the rotation angle θ1 of the blade 23 is naturally θ1<θd, so the blade rotation direction detector 1
2 outputs a signal 1 ev corresponding to the rotation angle θ1, and this signal 1 ev1 is applied to the comparison circuits 13 and 14.

Then, the comparator circuit 13 outputs a signal C1 based on the input signal +eV1 and adds it to the AND circuit 15.
4 outputs the gate signal gl (Fig. 4b) based on lev+〈E3 and adds it to the gate circuit 9.
Open L・ru.

Now, the load applied to the blade 23 increases and at time t1
For example, assume that the comparator circuit 6 outputs an overload signal e6.

The OR circuit 8 outputs a signal eB (FIG. 4a) based on the signal e6 and applies it to the pulse generator 11 via the gate circuit 9.

When the pulse generator 11 receives the signal e8, it outputs a pulse signal P1 (C in the figure) and applies it to the AND circuits 15 and 16.

Therefore, the AND circuit 150 condition is satisfied and the AND circuit 1
5 outputs a signal S1 (same as the pulse signal P1),
The solenoid valve 200 and solenoid 20Sa are energized for a time T1.

The solenoid valve 20 is switched to the position 20A during this time T1, and the circular plate 22 is moved counterclockwise by θ through the hydraulic motor 21. Rotate it slightly.

Therefore, the rotation angle of the blade 23 increases by θ7 and increases by θ1+
θT (d in the same figure), and the blade 23 is increased by this increase.
The negative load applied to is reduced.

In this way, the blades 23 are sequentially rotated counterclockwise during L after the pulse signal P1 is generated (d in the same figure).
) reduce the load.

Then, at time j m, the rotation angle θ of the blade 23 is
When the angle reaches the maximum dog angle θ, the blade rotation direction detector 12
The output signal 1ev becomes 1ev1≧E3 with respect to the reference value E3 of the comparator circuit 140, and as described above, the gate signal g1
is no longer output from the comparator circuit 14 (b in the figure), the gate circuit 9 is closed, and at the same time, the gate signal g2 is output (e in the figure), and the gate circuit 17 is opened.

Therefore, the pulse generator 11 does not output the pulse signal P1 (C in the figure), the solenoid valve 20 is switched to the middle position 20C, and the blade 23 is moved to the maximum rotation angle θ.

It is stopped and held at the position (d in the same figure, Fig. 2).

Even if the blade 23 reaches the state where the rotation is controlled to the maximum rotation angle θY as described above, the load applied to the blade 23 does not decrease, and the overload signal e6 is still output. In response to this, the OR circuit 8 continues to output the signal e8 (a in the figure).

This signal e8 is passed through the gate circuit 17 to the pulse generator 1.
Added to 9.

When this signal e8 is applied, the pulse generator 19 outputs a pulse signal P2 from the time tm when the signal e8 is applied (f in the figure), and energizes the solenoid valve 240 and solenoid 24S.

Solenoid valve 24 is switched to position 24A during time T2 when solenoid 24S is energized.

Therefore, the lift cylinders 25 and 26 are shortened to move the flade 23 up by hT (g in the figure).

As the blade 23 moves upward, the load applied to the blade 23 decreases.

In this way, as the blade 23 is sequentially controlled to move up in accordance with the pulse signal P2, the load is reduced.

It is assumed that the above-mentioned overload signal e6 is no longer output at time tn when the blade 23 is controlled to move up to the height hδ ((g) in the figure).

Therefore, the signal e8 of the OR circuit 8 becomes O (a in the figure),
The pulse signal P2 is no longer output from the pulse generator 19 (f in the figure).

Therefore, the solenoid valve 24 is switched to position 24B, and the lift cylinders 25,26 are stopped in that position to stop and hold the blade 23 at the aforementioned height hδ.

By controlling the blade 23 as described above, the load applied to the blade 23 can be reduced.

Although the blade control using the overload signal e6 has been described in the above embodiment, the blade control can be performed in the same manner as described above even with the slip signal e7.

Furthermore, in the above embodiment, the case where the rotation of the blade is controlled in the counterclockwise direction has been explained, but in the case where the rotation is controlled in the clockwise direction in the opposite direction, the same procedure as described above is carried out. be able to.

However, in the present invention, as described above, the load is reduced by rotating the blade in the direction of the initially set angle of the blade and increasing the rotation angle. It goes without saying that it is necessary to set the initial blade angle in a clockwise direction.

As explained above, according to the present invention, blade overload is detected in both a decrease in the engine speed of the wheel and a wheel slip. be able to.

Moreover, first, the blade is rotated to reduce the load (・
However, by controlling the blade upward movement only when there is an overload, the finished surface will not become uneven as long as there is no excessive overload (as long as the load is reduced).

Furthermore, there are excellent effects such as the operator learning advanced operating techniques and being able to operate the grader safely and easily, and reducing the load without reducing work efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the automatic grader blade control device according to the present invention, Fig. 2 is an explanatory diagram of the operation of the blade shown in Fig. 1, and Fig. 3 is the direction of rotation of the blade used in this device. FIG. 4, which is a diagram showing one embodiment of the detector, is a graph showing output signal waveforms of each part of the circuit shown in FIG. 1 and control of the blade. 1... Engine rotation speed detector, 2... Throttle lever opening detector, 3... Idle wheel rotation speed detector, 4, 5
... Arithmetic circuit, 6, 7, 13, 14... Comparison circuit,
8...OR circuit, 9,17...gate circuit, 1 0
．． 1 8...Pulse width variable device, IL19...Pulse generator, 12...Blade rotation direction detector, 15.1
6...AND circuit, 20.24...Solenoid valve, 21.
... Hydraulic motor, 22 ... Circular plate, 23 ... Blade, 25, 26 ... Lift cylinder, 27.28 ...
- Hydraulic pump, 31 to 34... Pipe, 30... Inuji, T1, T2... Drain tank.

Claims (1)

[Claims] 1. A means for obtaining a blade overload signal based on a comparison between the engine speed and the throttle lever opening, and a means for obtaining a wheel slippage signal due to a blade overload based on a comparison between the engine speed and the idle wheel speed. means for obtaining a signal; means for obtaining a blade rotation signal having a polarity and magnitude corresponding to the rotation direction and rotation angle of the blade relative to the traveling direction of the wheel; and the overload signal; Based on the L deviation of the slip signal and the blade rotation signal, when the blade is rotated in a direction in which its rotation angle increases and the blade rotation signal exceeds a certain value, An automatic grader blade control device comprising means for stopping rotation and moving the blade upward.