JPS6231765A - Controller for static hydraulic driving - Google Patents

Abstract

PURPOSE:To make it possible to stop the movement of a hydraulic actuator caused by a discrepancy on a control system by executing a position control when a speed command signal is zero and the speed of a hydraulic actuator is less than the specified value and by executing a speed control at the time except for it. CONSTITUTION:In a judgement circuit, when it is judged that a speed command signal Ws of a hydraulic actuator is zero and the speed signal Wa of the hydraulic actuator is less than the specified value, a speed signal of the hydraulic actuator is input into a integrator 19 so as to execute a position control of the hydraulic actuator by the use of a position signal which is made by multiplying its output by proportional gain to stop the movement of the hydraulic actuator. When it is judged in a judgement circuit that the above-mentioned condition is not met, a usual speed control of the hydraulic actuator is executed. Hereby, even if there is a discrepancy on a control system, it is possible to stop the hydraulic actuator surely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydrostatic drive control device used in construction machines such as hydraulic excavators or other industrial machines.

[Conventional technology]

An example of a conventional hydrostatic drive device is one constructed as shown in FIG. In the figure, 1 is a prime mover, 2 is a variable displacement hydraulic pump (hereinafter referred to as a hydraulic pump) driven by this prime mover 1, 3 is a hydraulic actuator such as a hydraulic motor, and 4 is driven by this hydraulic actuator 3. load,
5 is an operating lever, 6 is a control device, and 7 is the above-mentioned hydraulic pressure according to the output of this control device 6. A swash plate drive device 8 is a crossover relief valve for changing the discharge capacity of the pump 3.

The hydraulic cylinder f2 and the hydraulic actuator 3 are connected to the pipes tH, l.
They are directly connected by z to form a closed circuit.

FIG. 5 is a control circuit diagram of the above-mentioned device, and 5 is an operating lever, and when this operation is performed, a speed command signal ω of the hydraulic actuator 3 is output.
3 is set to change.

9 is this speed command signal ω8 and the actual hydraulic actuator 3
This is a comparison point that compares the speed signal ω8 with the speed signal ω8 and outputs the speed deviation Δω. 10 inputs the speed deviation Δω and sets the set differential pressure P.
1 is a function generator that outputs s, and 1 is a set differential pressure P output from this function generator 10 and the actual hydraulic actuator 3.
a comparison point that compares the operating differential pressure P of and outputs the differential pressure deviation ΔP;
12 is a control calculator which inputs the differential pressure deviation ΔP of this comparison point 11 and calculates the pressure control signal e, 14 is a feedback gain, and 13 is a signal ea obtained by multiplying the speed signal of the hydraulic actuator 3 by the foot notch r in 14. This is an addition point that adds the pressure control signal e of the control calculator 12 and outputs the signal e. 7 is a swash plate drive device, and 15 is a hydraulic drive system.

In the hydrostatic drive device configured as described above, when the operating lever 5 is operated, a speed command signal ω of the hydraulic actuator 3 is generated.
3 is output and compared with the actual speed signal ω1 of the hydraulic actuator 3 at a comparison point 9. Based on the speed deviation Δω, the function generator 10 outputs the set differential pressure P3 of the hydraulic actuator 3.
Actual operating pressure P8 of hydraulic actuator 3 at comparison point 11
compared to A pressure control signal e is determined by the control calculator 12 using the differential pressure deviation ΔP at the comparison point 11, and is added to the signal e obtained by multiplying the speed signal ω3 of the hydraulic actuator 3 by the feedback die/14 at the addition point 13. This signal e drives the swash plate drive device 7, changes the discharge capacity of the hydraulic pump 2, and controls the operating pressure and speed of the hydraulic actuator 3.

[Problem that the invention seeks to solve]

The conventional hydrostatic drive control system described above performs speed control by feeding back the speed of the hydraulic actuator 3, so even if the operating lever 5 is neutral and the speed command signal is zero, the control system's electrical The disadvantage is that it cannot be stopped due to a shift in the neutral point or a mechanical shift in the neutral point.

Therefore, the present invention provides a hydrostatic drive control device that is capable of stopping the movement of a hydraulic actuator caused by deviations in the control system, such as deviations from electrical neutrality and mechanical neutrality, when the operating lever is in the neutral position. The purpose is to provide

[Means for solving problems]

In order to achieve the above object, the present invention is constructed as follows. That is, in a hydrostatic drive device in which a variable displacement expansion hydraulic pump and a hydraulic actuator that drives a load are directly connected through a conduit to form a closed circuit, the speed command is approximately zero in the circuit that performs speed control based on the speed command of the hydraulic actuator. and an integrator that is activated by the output of the determination circuit and integrates the speed of the hydraulic actuator when the above condition is satisfied. The present invention is characterized in that when the above-mentioned conditions are satisfied, position control is performed using the output value of the integrator to stop the hydraulic actuator, and when the above-mentioned conditions are not satisfied, speed control is performed.

[Effect]

With this configuration, the determination circuit determines the condition that the speed command signal is zero and the speed signal of the hydraulic actuator is less than a predetermined value, and from the moment the condition is met, the integrator operates and the speed signal of the hydraulic actuator is The signal obtained by integrating and multiplying the output by a proportional gain can be regarded as a position signal, and the signal is fed back to the speed command signal. The speed command signal is zero and can be regarded as a position command signal, and the position of the hydraulic actuator is controlled by inputting the deviation from the position signal to a conventional speed and pressure control circuit. Since the speed command signal for the hydraulic actuator is zero, the movement of the hydraulic actuator can be stopped by performing stop control.

〔Example〕

Hereinafter, one embodiment of the hydrostatic drive control device of the present invention will be described with reference to FIGS. 1 to 3.

Figure 1 shows this control circuit, and since the speed and pressure control circuit in Figure 1 is the same as Figure 5,
The explanation thereof will be omitted here, and a stop control circuit different from that shown in FIG. 5 will be explained.

That is, the configuration of the stop control circuit consists of function generators 16 and 17 and a logic operator 18. The function generator 16 receives the output signal ω of the operating lever 5 as an input, and outputs a logical value O or 1 as an output. Function generator 1
Reference numeral 7 inputs the speed signal ω of the hydraulic actuator 3 and outputs a logical value of 0 or 1 similarly to the function generator 16 described above.

The logical operator 18 calculates a logical product from the outputs of the function generators 16 and 17. The integrator with reset 19 integrates the speed signal ω1 of the hydraulic actuator 3 based on the output of the logic operator 18, and outputs a position signal. FIG. 2 shows the characteristic diagram of the function generator 10, and FIG. 3 shows the characteristic diagram of the function generator 16, 17.

The operation of the control circuit configured as described above will be explained below.

When the operation shown in Fig. 1 returns the sheath 5 to neutral, the output ω becomes a value near zero, and the function in Fig. 3 enters the range between 1Δω and Δω, and the function generator s 3 16 has a logic value of 1. Output. Also, hydraulic actuator 3
When nearing a stop, the speed signal ω8 becomes -Δω according to the function shown in Figure 3.
and Δω, the logical value is 1 from the function generator 17.
is output. The logic values output from the function generators 16 and 17 are input to the logic operator 18, where a logical product is calculated. As described above, when the outputs of the function generators 16 and 17 are both 1, the logical state becomes 1, and an output is generated from the logic operator 18. This controls the integrator 19 with series reset, and has the function of performing integration when the output of the logical operator I8 is 1, and outputting O when the output is 0.

Therefore, when the logical product of the logical operator 18 becomes 1, the speed signal ω8 of the hydraulic actuator 3 is integrated, and the signal θ8 obtained by multiplying the output by the proportional gain 20 is obtained at the comparison point 9 and the operating lever 5
is compared with the output signal ω of . Output signal ω of operating lever 5
is 0 and the hydraulic actuator 3 is moving at a negative speed in the range from O to -Δω, the signal θ obtained by multiplying the output of the integrator with limit 19 by the proportional dyne 20 is negative, so at the comparison point 9 The speed deviation Δω of is positive.

On the other hand, the function generator 10 has the characteristics shown in FIG. It is compared with the operating differential pressure P8 of the actuator 3, and the control calculator 12 obtains the pressure control signal e using the deviation ΔP, and the addition point 13 calculates a signal e1 obtained by multiplying the speed signal ω by the feed/input 14. The swash plate drive device 7 is operated by the signal e obtained by adding both of them, and the discharge capacity of the hydraulic pump 2 is changed and the hydraulic actuator 3 is controlled to be stopped.

When the output signal ω of the operating lever 5 is O, the hydraulic actuator 3
When is moving at a positive speed in the range from O to Δω, the opposite effect occurs. In other words, integrator with limit 19
The signal θ1 obtained by multiplying the output of by a proportional gain of 20 becomes positive,
The speed deviation Δω at the comparison point 9 is negative, and the function generator 10
A set differential pressure Ps that generates a negative speed is output from the hydraulic actuator 3, and the hydraulic actuator 3 is controlled in the direction of stopping.

When the operating lever 5 is operated, the output signal ω3 is -Δω3 and Δ
When the range of ω3 is exceeded, the output of the function generator F6 becomes O. Accordingly, the output of the logical operator 18 becomes O, so the integrator with reset 19 stops integrating and outputs O, so it stops. Control is released.

As described above, according to the embodiment of the present invention, the movement of the hydraulic actuator 3 occurs due to the neutral deviation K of the control system, such as electrical neutral deviation or mechanical neutral deviation when the operating lever 5 is in the neutral position. can be stopped.

〔Effect of the invention〕

The present invention as described above provides a circuit for speed control based on a speed command of the hydraulic actuator in a hydrostatic drive device in which a variable displacement hydraulic pump and a hydraulic actuator for driving a load are directly connected through a pipe to form a closed circuit. a determination circuit that determines a condition where the speed command is approximately zero and the actual speed of the hydraulic actuator is equal to or less than a predetermined value; and an integrator that is activated by the output of the determination circuit when the above conditions are met and integrates the speed of the hydraulic actuator. In addition, when the above conditions are met, position control is performed using the output value of the integrator to stop the hydraulic actuator, and when the above conditions are not met, speed control is performed.

Therefore, it is possible to provide a hydrostatic drive control device that is capable of stopping the movement of a hydraulic actuator that occurs due to deviations from neutrality in the control system, such as deviations from electrical neutrality and mechanical neutrality when the operation lever is in neutral. .

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram showing an embodiment of the hydrostatic drive control device of the present invention, FIG. 2 is a characteristic diagram of the function generator 10 of FIG. 1, and FIG. 3 is a characteristic diagram of the function generator 16 of FIG. .17 characteristic diagram, FIG. 4 is a basic configuration diagram of a hydrostatic drive device, and FIG. 5 is a conventional hydrostatic drive control circuit diagram. 1... Prime mover, 2... Variable displacement hydraulic pump, 3.
...Hydraulic actuator, 5...Operation lever, 9...
Comparison points 1.16.17...Function generator, 18...Logic operator, 19...Integrator with limit, 20...Proportional dyne, ω...Speed command of hydraulic actuator, ω・
...Actual hydraulic actuator speed. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3D

Claims (1)

[Claims] In a hydrostatic drive device in which a variable displacement hydraulic pump and a hydraulic actuator that drives a load are directly connected through a conduit to form a closed circuit, the speed command is approximately zero in the circuit that performs speed control based on the speed command of the hydraulic actuator, and A determination circuit that determines the condition under which the actual speed of the hydraulic actuator is equal to or less than a predetermined value is added, and an integrator that is activated by the output of the determination circuit and integrates the speed of the hydraulic actuator when the above condition is met. A hydrostatic drive control device characterized by performing position control using an output value of an integrator to stop a hydraulic actuator, and performing speed control when the above conditions are not satisfied.