JPH0330753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to an electromagnetic proportional valve control device, and more particularly, to an electromagnetic proportional valve control device that drives an electromagnetic proportional valve with good resolution and hysteresis characteristics.

<Prior Art> Conventionally, in order to control the operation of an electromagnetic proportional valve that moves the valve body in proportion to the current value to perform proportional control of fluid flow rate and proportional pressure control, a method as shown in Fig. 6 has been used. A rectangular wave is generated by supplying the sawtooth wave output from the sawtooth wave generation circuit 31 to the switching circuit 32, which is amplified to a predetermined level by the transistor amplifier 33, and the solenoid 34 of the electromagnetic proportional valve is energized. An electromagnetic proportional valve control device is provided in which a switching transistor 35 to be controlled is turned on and off. Further, a surge absorption circuit including a resistor 36 and a reversely connected diode 37 connected in series is connected in parallel with the solenoid 34 (see Japanese Patent Laid-Open No. 54-28018).

Therefore, the state is equivalent to that when the average voltage signal determined by the ON-OFF time ratio of the rectangular wave is supplied to the solenoid 34, so the valve body is opened so that the opening degree corresponds to the average voltage. It is possible to perform proportional control of flow rate and proportional control of fluid pressure.

In addition, when performing the above operations,
The frequency of the rectangular wave signal applied to the solenoid 34 is predetermined, and the voltage applied to the solenoid 34 repeats ON and OFF at a predetermined rate every cycle determined by this frequency, so that the valve body is always kept at a very low level. Vibrations can continue within a certain range and can be maintained without static friction, improving resolution and
Hysteresis characteristics can be improved.

<Problems to be solved by the invention> In the electromagnetic proportional valve control device having the above configuration,
The frequency of the square wave signal is predetermined according to the characteristics of the electromagnetic proportional valve and drive system, and the ON-
By changing the OFF ratio, the movement position of the valve body can be controlled.
As for the vibration range of the valve body, from the viewpoint of improving resolution and improving hysteresis characteristics, the current applied to the solenoid 34 should be varied as much as possible within a range that does not affect the actual flow rate proportional control and pressure proportional control. It is preferable to do so.

Fluctuations in the current applied to the solenoid 34 will be explained in detail.

If only a diode is used as a surge absorption circuit, a large current will flow through the circuit consisting of the diode and solenoid in series the moment the square wave signal turns OFF, and the amplitude of the maximum and minimum current values will become small, so the diode 37 and A resistor 36 is connected in series.

However, when such a surge absorption circuit is adopted, the current that gradually increases due to the action of the inductance of the solenoid itself while the rectangular wave signal is ON decreases when the rectangular wave signal is OFF. However, if the voltage applied to the solenoid is low, the response at startup will be poor, and the amount of current change will be too small when the average voltage is low, resulting in a sufficient vibration effect on the valve body. There is a problem that it becomes impossible to obtain.

In order to solve this problem, it is conceivable to increase the voltage applied to the solenoid 34, but in this case, the amount of current change in a state where the average voltage is high will be too large, and the flow rate proportional control, pressure proportional control A new problem will arise in that the control will be affected.

<Purpose of the Invention> This invention has been made in view of the above-mentioned problems, and aims to increase the amount of vibration when the amount of movement of the valve body is small, and to increase the amount of vibration when the amount of movement of the valve body is large, exceeding the allowable limit. It is an object of the present invention to provide an electromagnetic proportional valve control device that can prevent

<Means for Solving the Problems> In order to achieve the above object, the electromagnetic proportional valve control device of the present invention includes an opening indicating means for generating a signal indicating the opening of the electromagnetic proportional valve, and a predetermined opening. an oscillating means that oscillates at a frequency, and a rectangular wave signal having an average voltage corresponding to the opening indicating signal by inputting an opening instruction signal from the opening indicating means and an oscillation signal from the oscillating means; a rectangular wave signal generation means for supplying a solenoid of the electromagnetic proportional valve; a reference frequency setting means for setting the oscillation frequency of the oscillation means as a predetermined reference value; , and frequency increasing means for increasing the oscillation frequency of the oscillation means in response to the opening instruction signal.

<Operation> With the electromagnetic proportional valve control device having the above configuration, when a signal instructing a relatively small opening degree from the opening degree indicating means is supplied to the rectangular wave signal generation means,
A reference oscillation frequency signal from an oscillation means operating based on the reference frequency setting means is supplied to the rectangular wave signal generation means, and a rectangular wave signal having the reference oscillation frequency and an average voltage corresponding to the opening degree instruction signal is generated. By generating and supplying the solenoid to the solenoid of the electromagnetic proportional valve, the valve body is moved to the position corresponding to the commanded opening degree with vibration within a range that does not affect proportional flow rate control and proportional pressure control. can be moved.

Further, when a signal instructing a large opening degree from the opening degree indication means is supplied to the square wave signal generation means, the frequency increasing means operates to make the oscillation frequency of the oscillation means correspond to the degree indication signal. The square wave signal generating means generates a square wave signal having the increased frequency and an average voltage corresponding to the opening instruction signal and supplies it to the solenoid of the electromagnetic proportional valve. The valve body can be moved to a position corresponding to the instructed opening while suppressing vibration within a range that does not affect the flow rate proportional control and the pressure proportional control.

<Example> FIG. 5 is a schematic vertical cross-sectional view showing an example of an electromagnetic proportional valve, in which the electromagnetic proportional valve 6 is equipped with a variable throttle 22c.
and a pressure compensating valve 50 that maintains a constant pressure difference before and after the variable throttle 22c.
a valve spool 2 having a large diameter portion and a small diameter portion;
A spring 24 that biases the valve spool 23 in a predetermined direction and a solenoid 5 that moves the valve spool 23 against the biasing force of the spring 24 are attached.

Therefore, a force corresponding to the voltage applied to the solenoid 5 acts on the valve spool 23, and the valve spool 23 is moved to a position where it balances the biasing force of the spring 24, and the gap between the inlet flow path 22a and the outlet flow path 22b is A predetermined constriction portion 22c is formed in the constriction portion 22c, and by keeping the differential pressure before and after the constriction portion 22c constant by a normally closed pressure compensating valve 50, proportional control of the flow rate can be performed.

FIG. 1 is a block diagram showing an embodiment of the electromagnetic proportional valve control device of the present invention.

The frequency is increased based on the characteristics of the opening instruction section 1 which outputs an opening instruction signal (see Fig. 2A), the electromagnetic proportional valve 6, and the drive system by inputting a command signal from an external control device (not shown). Based on the characteristics of the frequency increase start point setting section 12 that outputs the start point setting signal (see Fig. 2B), the power supply section 9, the electromagnetic proportional valve 6, and the drive system, the standard of the square wave signal to be applied is determined. The reference frequency setting section 11 outputs a frequency setting signal.

The opening instruction signal output from the opening instruction section 1 and the feedback signal from the solenoid 5 that drives the electromagnetic proportional valve 6 are input to the constant current calculation section 2 so that the difference between the two input signals becomes zero. Outputs the calculated calculation output signal. Further, the oscillation unit 10 receives the reference frequency setting signal outputted from the reference frequency setting unit 11 as input and oscillates at the reference frequency.
By supplying the reference frequency oscillation signal to one input terminal of the comparator 3 and supplying the above-mentioned calculation output signal to the other input terminal of the comparator 3, a rectangular wave signal with a predetermined duty ratio is output. Then, by supplying the rectangular wave signal to the gate terminal of the power switching section 4 to which the power supply voltage from the power supply section 9 is supplied, a power supply voltage signal having the duty ratio described above is supplied to the solenoid 5, The electromagnetic proportional valve 6 can be driven to a specified opening degree with vibration in a minute range.

The opening degree instruction signal is input to the comparator 13 together with the frequency increase start point setting signal, and when the opening degree instruction signal becomes larger, a frequency increase instruction signal is supplied to the frequency increase amount calculating section 14. In addition to the frequency increase instruction signal, the frequency increase calculation section 14 is supplied with the opening instruction signal and an increase rate setting signal from the frequency increase rate setting section 15,
The frequency increase calculation signal is sent to the reference frequency setting section 1.
Supply to 1.

The feedback from the solenoid 5 to the constant current calculation section 2 is provided by a current detection section 7 that detects the current of the solenoid 5 and converts it into a voltage;
The smoothing section 8 smoothes the alternating current component included in the output signal from the constant current calculation section 2, and the smoothing section 8 can be omitted. is also possible.

Furthermore, the output waveform from the oscillation section 10 is not particularly limited, but is preferably a triangular wave or a sawtooth wave.

The operation of the electromagnetic proportional valve control device having the above configuration is as follows.

() When a small opening is commanded (see the area in FIGS. 2 and 4), in this case, the opening instruction signal is smaller than the frequency increase start point setting signal, so the frequency increase calculation unit 14 doesn't work.

Therefore, based on the reference frequency setting signal from the reference frequency setting section 11, the oscillation section 10 outputs an oscillation signal of the reference frequency.

Then, the output signal from the constant current calculation section 2 which receives the opening instruction signal and the feedback signal as input, and the above-mentioned oscillation signal are input to the comparison section 3, which generates a rectangular wave signal of a duty corresponding to the magnitude relationship between the two signals. Since it is input to the gate terminal of the power switching unit 4, the power supply voltage is applied to the solenoid 5 with the same duty as the rectangular wave signal. As a result, the solenoid 5 applies a driving force corresponding to the average applied voltage to the valve spool 23, vibrates minutely and comes to a halt at a position equal to the biasing force of the spring 24, and the flow rate corresponding to the opening command is increased. Proportional control can be performed.

() When a large opening is commanded (see the middle area in Figures 2 and 4), in this case, the opening command signal is larger than the frequency increase start point setting signal, so the comparator 13 issues a frequency increase command. The signal is output, and the frequency increase calculation section 14 calculates a frequency increase calculation signal determined based on the opening degree instruction signal and the increase rate setting signal, and supplies it to the reference frequency setting section 11 . Therefore, the reference frequency setting section 11 outputs a frequency setting signal increased in accordance with the opening instruction signal, and the oscillation section 10
, outputs an oscillation signal of a constant frequency according to the frequency setting signal.

As a result, a rectangular wave voltage having the above frequency and a duty corresponding to the opening degree instruction signal is supplied to the solenoid 5. In this case, since a large opening degree is instructed, the vibration of the valve spool 23 will increase if left as is, but since the frequency has been increased, the vibration will be maintained within the allowable range without increasing. In this state, the valve spool 23 can be moved to a position corresponding to the opening instruction signal to perform proportional flow rate control.

FIG. 3 is a block diagram showing another embodiment,
The difference from the above embodiment is that the frequency increase start point setting section 12 is provided in plurality, and the comparison section 13 is provided in plurality.
, each frequency increase start point setting section 121, 122...
...12n, and the switching sections 171, 1 are operated by the output signals from the comparison sections 131, 132...13n.
72...17n and each switching section 171,1
72...17n as frequency increment setting sections 161, 162...16n that output frequency increment signals supplied to the reference frequency setting section 11, and the configuration of other parts is the same.
The same parts are given the same reference numerals.

Therefore, in the case of this embodiment, the oscillation frequency of the oscillation section 10 is increased in stages in response to an increase in the opening degree instruction signal, and even when the opening degree becomes large, the vibration of the valve spool 23 is reduced. This means that the flow rate proportional operation can be performed while suppressing the flow rate within the allowable range.

Note that the present invention is not limited to the above-described embodiments, and it is possible to perform pressure proportional control, for example. ), and various other design changes can be made without changing the gist of the invention.

<Effects of the Invention> As described above, the present invention has the advantage that when a rectangular wave voltage is applied to the solenoid of an electromagnetic proportional valve to move the valve body to a desired position with minute vibrations, the average applied voltage is While the voltage is small, the square wave voltage frequency is held at a small predetermined value, and when the average applied voltage is large, the square wave voltage frequency is increased. This has the unique effect of being able to eliminate friction and perform accurate proportional control in response to external commands.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the electromagnetic proportional valve control device of the present invention, Fig. 2 is a block diagram showing signal waveforms of each part, Fig. 3 is a block diagram showing another embodiment, and Fig. 4. FIG. 5 is a longitudinal sectional view showing an example of an electromagnetic proportional valve, and FIG. 6 is a block diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1...Opening degree indicating part, 3...Comparing part, 4...Power switching part, 5...Solenoid, 6...Solenoid proportional valve, 10...Oscillating part, 11...Reference frequency setting part, 12, 121, 122... 12n... Frequency increase start point setting section, 13, 131, 132...
...13n... Comparison section, 14... Frequency increase calculation section, 15... Frequency increase rate setting section, 16, 16
1,162...16n...frequency increment setting section,
171, 172...17n...Switching section.

Claims (1)

[Scope of Claims] 1. An opening indicating means for generating a signal indicating the opening of the electromagnetic proportional valve, an oscillating means for oscillating at a predetermined frequency, and an opening indicating signal from the opening indicating means and the oscillating means. Rectangular wave signal generating means receives an oscillation signal from the oscillator, generates a rectangular wave signal having an average voltage corresponding to the opening instruction signal, and supplies the generated rectangular wave signal to the solenoid of the electromagnetic proportional valve; and a frequency increasing means for increasing the oscillation frequency of the oscillation means in response to the opening instruction signal when the opening instruction signal is larger than a predetermined reference value. An electromagnetic proportional valve control device comprising: 2. The electromagnetic proportional valve control device according to claim 1, wherein the frequency increasing means continuously increases the oscillation frequency in response to the opening signal. 3. The electromagnetic proportional valve control device according to claim 1, wherein the frequency increasing means increases the oscillation frequency stepwise in response to the opening signal.