JPH0792162B2 - Control device for solenoid proportional valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device having improved responsiveness of a solenoid proportional valve controlled by a pulse width modulation method.

(Prior Art) The current input to the electromagnetic coil of the solenoid proportional valve is a pulse signal (intermittent current) having a pulse width corresponding to the control input by modulating the pulse width of the control input. The valve opening is proportionally controlled in accordance with the above.

By the way, in such a solenoid proportional valve control device, in order to accurately control the output with respect to the input, it is usual to compare the control input with the exciting current of the electromagnetic coil and perform feedback control.

In this case, in order to operate the control system stably, a certain response delay is given to the control input.

Therefore, as shown in FIG. 4, the average value of the actual current B which is controlled by the pulse width modulation and is applied to the electromagnetic coil during the transient when the input signal A changes abruptly is The input signal A is followed with a certain time delay.

In this case, the delay time t1 is much longer than t2, compared to the case where the input signal A is amplified as it is without pulse width modulation to generate the drive current C.

(Problems to be Solved by the Invention) However, if the time constant of the feedback control system is reduced so as to eliminate such a delay, then a problem of excessive response occurs when the input signal changes, and the electromagnetic coil The exciting current causes hunting due to overshoot, which causes a problem that the opening of the solenoid proportional valve becomes unstable.

The present invention is intended to solve such a problem, and an object of the present invention is to provide a control device for a solenoid proportional valve, which improves the response during transient while maintaining the stability of the feedback control system. .

(Means for Solving Problems) The present invention calculates a feedback control signal by feeding back a detection value of a drive current of an electromagnetic coil to a signal setting device for inputting a control signal and an input value from the signal setting device. Control circuit, a pulse width modulation circuit that outputs a pulse signal having a pulse width corresponding to the output from this control circuit and the output from the generation circuit that generates a triangular wave of a predetermined period, and the output pulse signal In a control device that includes a drive circuit that outputs an electromagnetic coil drive current and that feedback-controls the opening of an electromagnetic proportional valve, a detection circuit that detects a deviation between an input value of the control signal and a detected value of the electromagnetic coil drive current. When,
A compensating circuit that outputs a compensation signal to the drive circuit or the pulse width modulation circuit when the deviation value is a predetermined value or more, and outputs the compensation signal when the deviation value is a predetermined value or more to the electromagnetic coil. The drive current is increased, and when it is below a predetermined value, feedback control is performed without outputting the compensation signal.

(Operation) In this way, the input value of the control signal increases rapidly,
When the deviation value from the drive current of the electromagnetic coil becomes larger than a predetermined value, the compensation circuit outputs a compensation signal. Since the output current of the drive circuit increases based on this compensation signal, the drive current of the electromagnetic coil increases with good response, and the opening degree of the electromagnetic proportional valve increases immediately.

On the other hand, when the deviation from the control input value becomes smaller than the predetermined value due to the sudden increase in the drive current of the electromagnetic coil, the output of the compensation signal stops and the normal feedback control is resumed. When the input value of does not change rapidly, stable control is maintained without excessively responding to the input value.

(Examples) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a control device, 1 is a signal setting device for inputting a control signal, 2 is an electromagnetic coil 10 described later.
Is a control circuit for adding the output from the drive current detection circuit 9 and the output of the input signal setting device 1 to generate a control signal.

Reference numeral 3 is a pulse width for synthesizing the control signal output from the control circuit 2 and the output of the triangular wave generating circuit 8 for generating a triangular wave of a predetermined frequency to output a pulse signal having a pulse width corresponding to the voltage value of the control signal. It is a modulation circuit. Reference numeral 7 is an electromagnetic coil drive circuit that outputs a drive current of the electromagnetic coil 10 based on the output of the pulse width modulation circuit 3. The electromagnetic coil 10 is excited in accordance with this drive current, and the valve opening of the solenoid proportional valve is adjusted. To do.

Next, 4 is a deviation detection circuit that outputs a signal corresponding to the deviation between the input signal from the signal setting device 1 and the detection signal fed back from the detection circuit 9, and this deviation output is predetermined in the compensation circuit 5. Compensation circuit 5 outputs a compensation signal so as to increase the electromagnetic coil drive current by a predetermined value when compared with the reference voltage. The compensation signal may be directly applied to the electromagnetic coil drive circuit 7 or may be applied to the input side of the pulse width modulation circuit 3.

Reference numeral 11 is a reference voltage setting device that outputs the predetermined reference voltage.

FIG. 3 shows a specific configuration of the deviation detection circuit 4 and the compensation circuit 5, etc. The arithmetic circuit IC1 creates a PWM control signal based on the control input signal and the electromagnetic coil detection signal. With the capacitor C1, the PWM control signal is delayed by a predetermined amount so that the control system operates stably.

The arithmetic circuit IC2 synthesizes this PWM control signal and a triangular wave of a predetermined frequency and outputs a pulse width modulation signal (driving signal).

The arithmetic circuit IC3 functions as a differential amplifier circuit by the resistors R2, R3, R4, and R5, and outputs a signal according to the deviation between the control input signal and the electromagnetic coil detection signal. Then, this deviation signal is compared with the reference voltage signal from the variable resistor VR1, and when it is equal to or higher than the reference voltage signal, the arithmetic circuit IC4 outputs the compensation signal.

With the diodes D1 and D2 and the resistor R6, the arithmetic circuit IC2 takes the logical sum (OR) of the compensation signal and the PWM control signal, and thus when the compensation signal is being output,
The control signal, whichever is larger, is input as it is, and pulse width modulation is performed based on this. When the compensation signal is input, the drive signal is set to be in the continuous energization state.

The above-mentioned structure will be described below with reference to the time chart of FIG.

If the control input signal (a) from the signal setter 1 suddenly rises from a small constant value until then, the pulse width of the output signal (b) of the pulse width modulation circuit 3 also increases correspondingly. Go.

However, the input to the pulse width modulation circuit 3 is changed by the control circuit 12 with a certain time delay corresponding to the difference from the detection value (c) from the electromagnetic coil detection circuit 9, so the pulse width modulation circuit 3 The pulse width of the output signal (b) does not increase rapidly.

However, the deviation detection circuit 4 detects the deviation between the control input signal (a) and the electromagnetic coil detection signal (c), and while the deviation is equal to or more than the predetermined reference value, the compensation circuit 5 outputs the compensation signal (d).
Is output. For this reason, the input of the electromagnetic coil drive circuit 7 rapidly increases by that amount, and in this way, the exciting current to the electromagnetic coil 10 eventually increases with good response corresponding to the control input signal. Along with this, the opening of the solenoid proportional valve changes.

On the other hand, in this way, the exciting current of the electromagnetic coil 10 increases and follows the input signal, and when the deviation becomes less than the reference value of the compensating circuit 5, the output of the compensating circuit 5 disappears. At this point, the normal feedback control is resumed and the operating characteristics are stabilized.

In this way, when the input signal changes abruptly, the opening of the solenoid proportional valve can be increased with good response.
When the input signal changes steadily, stable control characteristics can be obtained by normal feedback control.

Since the drive current of the electromagnetic coil 10 is a pulse current, the output of the detection circuit 9 changes into a wave shape with a first-order delay due to the self-inductance of the electromagnetic coil 10. Therefore, in the deviation detection circuit 4, the electromagnetic coil 10
Even if the exciting current of becomes steady, it fluctuates with a predetermined amplitude.
There is always a deviation from the control input signal, but the compensation circuit 5
Then, the comparison reference value is set to a value larger than the average deviation value in the steady state so that the compensation circuit 5 does not output the compensation signal in the steady state.

As described above, according to the present invention, the input value of the control signal sharply increases, and the deviation value between the input value of the control signal and the detected value of the driving current of the electromagnetic coil is a predetermined value. If it becomes larger than that, the compensating circuit outputs the compensating signal and increases the output current of the driving circuit during that time, so that the driving current of the electromagnetic coil increases in response, and the opening of the solenoid proportional valve increases in response. On the other hand, in a steady control state in which the deviation value is smaller than a predetermined value while being able to increase, the compensation signal from the compensation circuit is not output, and normal feedback control is performed, which corresponds to the input value of the control signal, Stable and highly accurate control characteristics are maintained.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, FIG. 2 is a concrete circuit diagram of a compensating circuit, etc., FIG. 3 is a waveform diagram showing operating characteristics, and FIG. 4 is a conventional drive for an input signal. It is explanatory drawing showing the relationship of a signal. 1 ... Input signal setting device, 2 ... control circuit, 3 ... pulse width modulation circuit, 4 ... deviation detection circuit, 5 ... compensation circuit, 7
...... Electromagnetic coil drive circuit, 9 ... Electromagnetic coil current detection circuit, 10 ... Electromagnetic coil.

Claims (1)

[Claims] 1. A signal setter for inputting a control signal, a control circuit for feeding back a detection value of a drive current of an electromagnetic coil to an input value from the signal setter to calculate a feedback control signal, and a control circuit for the control circuit. Pulse width modulation circuit that outputs a pulse signal having a pulse width corresponding to the output of the pulse wave and the output from the generation circuit that generates a triangular wave of a predetermined period, and a drive circuit that outputs an electromagnetic coil drive current corresponding to this output pulse signal In the control device for feedback controlling the opening of the solenoid proportional valve, a detection circuit for detecting a deviation between the input value of the control signal and the detected value of the electromagnetic coil drive current,
A compensating circuit that outputs a compensation signal to the drive circuit or the pulse width modulation circuit when the deviation value is a predetermined value or more, and outputs the compensation signal when the deviation value is a predetermined value or more to the electromagnetic coil. A control device for an electromagnetic proportional valve, characterized in that a drive current is increased and feedback control is performed without outputting the compensation signal when the drive current is below a predetermined value.