JPS6018841B2 - Automatic control device for construction vehicle work equipment - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to an automatic control machine for a construction vehicle ball.

BACKGROUND ART Conventionally, in the automatic control of working machines for construction vehicle balls, electromagnetic valves have been used for ON-OFF control using servo valves due to concerns about working oil contamination, vibration resistance, and durability.

However, since this solenoid valve only performs ON-OFF control, the flow rate therethrough fluctuates depending on the oil temperature. As a result, the gain of this control system varies depending on the oil temperature; when the oil temperature is high and its viscosity is low, the gain becomes large, and when the oil temperature is low and its viscosity is large, the gain becomes small. Therefore, if the gain of this control system is adjusted to be the optimum gain when oil streaks are low, when oil overflow becomes high, the control system becomes unstable and oscillates.

On the other hand, if the gain is adjusted to be optimal when the oil temperature is high, the response will be slow and the steady-state deviation will be large when the oil temperature is low. The present invention has been made in view of the above-mentioned circumstances, and is an automatic construction machine for construction vehicle necks that can always ensure the optimum settling time of the working machine and configure a stable system regardless of the temperature of the hydraulic oil. The purpose is to provide a control device.

According to this invention, there are two series of flow rate control solenoid valves for the hydraulic cylinder that drives the work machine of the construction tactician, and the absolute value of the deviation between the work machine position and the target position is equal to or greater than a first set value. When , the two solenoid valves are operated simultaneously, and when the absolute value of the deviation is less than or equal to the first set value and greater than or equal to the second set value (second set value <first set value), In an automatic control device for a working machine for a construction vehicle that operates only one of the two electromagnetic valves, means for reducing the first set value in response to oil overflow caused by the operation of the hydraulic cylinder. is installed to compensate for changes in the displacement speed of the work equipment due to changes in hydraulic oil temperature, creating a stable system.

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

FIG. 1 is a system diagram showing one embodiment of the present invention, where 1 is a blade of a movable vehicle, for example, a bulldozer, and 2 is a hydraulic cylinder that moves the blade 1 up and down.

The position of the blade 1 is detected electrically by a suitable position detector (not shown). A set value signal E which determines the set position of the blade 1 is emitted from the position detector.
compared to This set value signal E can be set in increments of IV from 10V to skin in order to lower the blade position from the position of 1 enemy on the ground, for example, to the ground surface of 0 enemies in the lower layer every 0.1 kite. Now, for example, when setting the set value signal E to lOW and setting the blade 1 to the upper lm position, if the signal level from the position detector is, for example, 7V, the deviation signal S having a deviation value of 3V will be can get.

The amplifier 3 amplifies the deviation signal S and outputs an amplified signal e, which is applied to the comparison circuit 4. The comparison circuit 4 includes, for example, comparators c, ~c4 and potentiometers P, ~P4 as shown in FIG.
The potentiometers P, , P3 and P
Constant voltages of 1 V and -V are applied to one of the fixed terminals 2 and P4, and the other terminal is grounded, respectively. The potentiometers P, , P2 are used to set the band widths, , 1, and the potentiometers P3, P4 are used to set the switching points 2, 1 (however, 1, 1 and 2). l),
Output voltage ±vp,,± corresponding to these values,, ±2
p2 is applied to one input side of the comparators c, to c4, respectively, and the signal e is applied to the other input side. Of course, these output voltages ±p, , ±p2 (where l〃p, l<lp2l) can be set as appropriate. comparator c
, , c2 outputs signals V, , -V, when the signal e is e>go, , e<-go, respectively, and comparators c3 and c4 output signals e>go2, eku-go2, respectively. , the signals V2,
-V2 is output. The signals V and -V are the solenoids a and b of the third layer switching solenoid valve (hereinafter referred to as solenoid valve) 5,
Then, signals V2 and -V2 are applied to solenoids a2 and b2, respectively, of solenoid valve 6, energizing each of these solenoids. The solenoid valve 5 is switched to the A position when the solenoid a is energized, to the B position when the solenoid q is energized, and to the intermediate layer c when both solenoids are not energized. The same applies to the solenoid valve 6. Therefore, the signal e becomes e>z2
, the comparison circuit 4 outputs the signals V, . V2 is output and the two solenoid valves 5, 6 are A, . Switching to the A2 position, the maximum amount of pressure oil is supplied from the hydraulic pump p to the cylinder 2, and the blade 1 is raised upward.

Here, the maximum amount of pressure oil is the amount of pressure oil discharged from the two electromagnetic valves 5 and 6 simultaneously. For example, if two solenoid valves 5 and 6 are used that have a capacity of 10〆/bar at a certain working pressure, the above maximum amount is 10〆/〆/〆:
20〆/means ribs. Further, the hydraulic pump P discharges pressurized oil at a predetermined pressure, which is at least the maximum amount. . Of the pressure oil discharged from the hydraulic pump P, if the two solenoid valves are in the ○N state, the pressure bottle amount exceeding the maximum amount is drained from a relief valve (not shown),
Similarly, if only one solenoid valve is in the ○N state, the amount of pressure oil that exceeds the capacity of that solenoid valve is drained from the relief valve. The blade position detector detects the position of the rising blade 1 moment by moment, and outputs a signal e, which corresponds to the deviation value s, <
e. < 2, the comparator circuit 4 outputs only the signal V, and only the solenoid valve 5 maintains the A position. Therefore, the oil supplied to the hydraulic cylinder 2 decreases, causing the blade 1 to rise at a low speed. , the signal e2 corresponding to the deviation value s2 is e2<・
, the solenoid valve 5 also becomes the middle layer and stops Play-Doh. Of course, the signals e and z. , ·2 are unipolar, it goes without saying that the solenoid valves 5, 6 are switched to the B, , B2 positions, respectively, and the blade 1 is lowered in the same manner as described above.
Now, as shown in Figure 3a, if the values of , , and 2 at the temperature To of the hydraulic oil (the viscosity of the hydraulic oil at this time is po) are set as shown in the figure, the signal e will be lower than 2. Assume that 6o is larger (6o = e - 2).

However, it is assumed that the signal e and the signal e have constant values in the following explanation. The comparator circuit 4 detects that the signal e is e>go2.
, outputs the signal V, ,V2 for the time period ,<e. <2
During time t2, only the signal V is output. Therefore, the solenoid valves 5 and 6 operate as described above, and the stroke displacement L of the cylinder 2 and the time t required for the displacement (t = RA 1 = constant)
The relationship is as shown in graph 1 in FIG. When the oil temperature rises to T, (T, >L), the viscosity at this time is p
, then p and kupo. Therefore, in order to keep the cylinder stroke displacement time t constant, it is necessary to shorten the maximum amount of pressurized oil supplied to the cylinder 2. For this reason, the above-mentioned potentiometer P3
, P4 and set the value of z2 as shown in Figure 3b.
(Go'2 > Go2). Therefore, signal e and
The deviation 6, (6, = e - 2) from 2 is 6, 6 o, and the time L' when the signal e is e>go'2 is t,'<t, and conversely, the time L' when the signal e is e>go'2 is t,'<t. <e,ku'2 Time group 2
' becomes t2 times t2'. Therefore, the operating time of the electromagnetic valve 6 becomes shorter and the operating time of only the electromagnetic valve 5 becomes longer, so that the stroke displacement of the cylinder 2 becomes as shown in the graph n' of FIG. 4. In addition, if the oil temperature drops and becomes T2 (T2 × To), then if the viscosity at this time is p2, then p2>
p. Therefore, the stroke displacement time t of the cylinder 2 is
In order to keep V constant, contrary to the above, the maximum pressure oil supply time t, which is supplied to the cylinder 2, must be lengthened.
The operator then operates the aforementioned potentiometers P3 and P4.
Adjust the value of 2 to ・r2(
Set to 2). Thus, the deviation 62 (62 = e - 2) between signal e and r2 is 6.<62, and the time t,'' at which signal e is e>2'') is t,
, and conversely, the signal e is <e. The time group 2'' where <d2'' becomes t2''< etc. Therefore, the operating time of the solenoid valve 6 becomes longer and the operating time of only the solenoid valve 5 becomes shorter, so the maximum pressure oil supply time is lengthened. , and the stroke displacement of cylinder 2 is now as shown in graph m in FIG.
By appropriately changing the value of 2 in accordance with the temperature of the hydraulic oil as described above, the cylinder stroke displacement time can be made constant regardless of changes in the temperature of the hydraulic oil. Also,
The total output flow rate of solenoid valves 5 and 6 is K, the output flow rate of solenoid valve 5 is K2, the time that solenoid valves 5 and 6 are simultaneously in ○N, and the time that only solenoid valve 5 is in ○N If it is 72, then
The average gain at that time, K,7,10K272TI+T2, can be kept constant regardless of the oil temperature, and optimal controllability can be obtained.

Although this embodiment describes the case where the potentiometers P3 and P4 are manually set to set the switching point ±2, the present invention is not limited to this, and the temperature of the hydraulic oil can be detected using a thermistor thermometer or the like. Of course, it may be possible to electrically detect it with a device and automatically set it based on the electrical signal.

As described above, according to the present invention, the hunting phenomenon can be substantially suppressed by changing the supply time of the maximum amount of pressurized oil supplied to the hydraulic system according to the temperature of the hydraulic oil, and the settling time of the hydraulic system can be changed depending on the oil temperature. It has the excellent effect of being able to remain constant regardless of changes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an automatic control device for a construction wheel work machine according to the present invention, FIG. 2 is a circuit diagram showing an embodiment of the comparison circuit of FIG. 1, and FIG. FIG. 4 is a diagram showing the operation of the circuit shown in FIG. 2, and FIG. 4 is a diagram showing the relationship between stroke displacement and time of the hydraulic cylinder shown in FIG. 1...Blade, 2...Cylinder, 3...
...Amplifier, 4... Comparison circuit, 5, 6...
...Solenoid valve, c, ~c4...Comparator, P, ~P
4...Potentiometer, P. ...Hydraulic pump, T...Tank. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A hydraulic cylinder that drives a working machine of a construction vehicle has two series of flow control solenoid valves, and when the absolute value of the deviation between the working machine position and the target position is greater than or equal to the first set value, the above 2. When the absolute value of the deviation is less than or equal to the first set value and greater than or equal to the second set value (second set value < first set value), the two solenoid valves are operated simultaneously. In an automatic control device for a working machine of a construction vehicle that operates only one of the two, the first setting value is reduced in response to an increase in the temperature of the hydraulic oil in the hydraulic cylinder, and An automatic control device for a working machine of a construction vehicle, characterized in that it compensates for changes in the displacement speed of the working machine due to temperature changes.