JP2525444Y2 - Electromagnetic proportional valve controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to an electromagnetic proportional valve control device used when a predetermined amount of gas is supplied to a gas combustion device via an electromagnetic proportional valve.

[Conventional technology]

The valve opening of the electromagnetic proportional valve is determined by varying the amount of current supplied to the proportional valve coil using a switching element. In this case, as one of the methods of varying the amount of current, there is a method of increasing or decreasing the voltage applied to the proportional valve coil. However, according to this method, the amount of heat generated by a transistor or the like used as a switching element increases, which may adversely affect control characteristics, life, and the like.

Therefore, in general, as a method of varying the amount of current, a method is employed in which the peak value of the voltage applied to the proportional valve coil is fixed and only the duty is varied. That is,
As shown in FIG. 4 (a), when a large current is passed through the proportional valve coil, a pulse current having a width W1 is supplied at a period T, and when a small current is passed, as shown in FIG. 4 (b). , A pulse current having a width W2 is supplied at a period T. As described above, only the pulse width is changed to vary the current, and the cycle T is constant. That is, the duty is changed under a constant switching frequency.

[Problems to be solved by the invention]

However, when the duty is reduced while the switching frequency is low, that is, FIG. 4 (b)
If the pulse width W2 is too small in comparison with the period T, the valve opening becomes unstable as shown in FIG. 5 (a), and the control characteristics deteriorate in a certain region.

Therefore, in order to eliminate such an unstable region, it is conceivable that the period T and the pulse width W2 in FIG. 4B are further reduced, and the duty is reduced while the switching frequency is high.

However, in this case, the valve opening differs between the case where the current is increased and the case where the current is decreased. As shown in FIG. 5 (b), a so-called hysteresis loop-like control characteristic is obtained. Had become.

The present invention has been made in view of the above circumstances, and provides an electromagnetic proportional valve control device that can always obtain stable control characteristics when controlling the valve opening degree by controlling the duty of the current to the proportional valve coil. It is intended to provide.

[Means for solving the problem]

According to the present invention, as a means for solving the above problem, a switching element is connected to a proportional valve coil, and a current flowing through the proportional valve coil is controlled by on / off control of the switching element. In the electromagnetic proportional valve control device that adjusts the opening of the electromagnetic proportional valve, based on predetermined control conditions, valve opening determining means for determining the opening of the electromagnetic proportional valve, and based on a signal from the valve opening determining means A duty adjustment signal output means for adjusting a duty when the switching element is turned on and off; a frequency adjustment signal output means for adjusting a switching frequency of the switching element in response to the duty adjustment; A switching element that outputs a pulse signal for driving the switching element based on a frequency adjustment signal; Comprising a drive means, the, moreover, the duty adjustment signal output means and said frequency adjustment signal output means, without changing the frequency of the pulse signal, in the case of changing the duty only to the target value, once,
The pulse width is changed by lowering the frequency without changing the duty, and thereafter, the frequency and the pulse width are adjusted so that the duty becomes the target value.

[Action]

In the above configuration, when the valve opening determining means determines the opening of the solenoid proportional valve based on a predetermined control condition, the duty adjusting signal output means outputs a duty adjustment signal for changing the duty when the switching element is turned on and off based on the determined opening degree. Is output.

The frequency adjustment signal output means outputs a frequency adjustment signal to change the switching frequency in response to the change in duty.

Since the switching element driving means drives the switching element based on the duty adjustment signal and the frequency adjustment signal, the duty of the proportional valve coil is always controlled at an appropriate frequency regardless of the magnitude of the current.

Then, when changing the duty to the target value, the frequency is once lowered with the same duty as the duty before the change and the pulse width is changed, and then the frequency and the pulse width are adjusted to set the duty to the target value. So that In this way, when the duty is changed,
The characteristic of the hysteresis loop that has conventionally occurred can be prevented.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an embodiment of the present invention, in which the amount of supplied gas is adjusted by an electromagnetic proportional valve, and water is supplied by combustion of the gas.
It is applied to a device for heating air or other refrigerants.

A DC power supply 2 is connected to an AC power supply 1, and a proportional valve coil 3 and a transistor 4 as a switching element are connected to an output side of the DC power supply 2. The transistor 4 is turned on / off by a control signal from the switching element driving means 5, and the on / off of the transistor 4
The current flowing through is controlled in duty.

On the other hand, the temperature difference detector 6 always detects the room temperature,
A signal relating to the deviation between the room temperature and the set temperature is output to the valve opening determining means 7.

The valve opening determination means 7 outputs a valve opening determination signal to the duty adjustment signal output means 8 and the frequency adjustment signal output means 9 based on the deviation signal. The duty adjustment signal output means 8 and the frequency adjustment signal output means 9 output a duty adjustment signal and a frequency adjustment signal to the switching element driving means 5, respectively.

Next, the operation of the embodiment of the present invention configured as described above will be described.

Now, it is assumed that a pulse current having a pulse width W1 is supplied to the proportional valve coil 3 in a cycle T by turning on and off the transistor 4, as shown in FIG. If the room temperature rises in such a state, based on the increased deviation signal from the temperature difference detector 6, the valve opening degree determination means 7
A valve opening determination signal in a direction to decrease the valve opening is output to the duty adjustment signal output means 8 and the frequency adjustment signal output means 9.

The duty adjustment signal output means 8 outputs a duty adjustment signal to the switching element driving means 5 based on the valve opening degree determination signal.
Also outputs this duty adjustment signal.

Then, the frequency adjustment signal output means 9 outputs a frequency adjustment signal to the switching element driving means 5 based on the valve opening degree determination signal and the duty adjustment signal. The frequency adjustment signal has a certain correspondence with the duty adjustment signal so that the electromagnetic proportional valve can perform a stable operation.

The switching element driving unit 5 receives such a duty adjustment signal and a frequency adjustment signal, and changes both the duty and the switching frequency to turn on and off the transistor 4. FIG. 2 (b) shows a waveform of a pulse current obtained by the on / off control of the transistor 4, wherein the pulse width is W2 and the cycle is T1.

According to such a change in the pulse current, when the duty is changed, the switching frequency always changes so as to be an optimum value. Therefore, there is no unstable region in the characteristic curve as shown in FIG. 5 (a), and the characteristic curve does not draw a hysteresis loop as shown in FIG. 5 (b).

By the way, according to the embodiment shown in FIG. 1, it is possible to obtain a duty control which does not cause a hysteresis loop as shown in FIG. Can be.

That is, initially, the pulse width Wa, as shown in FIG.
Assuming that a pulse current having a period Ta and a duty D1 is flowing through the proportional valve coil 3, once only the frequency of this pulse current is sufficiently reduced to obtain a pulse width as shown in FIG.
The pulse current is changed to Wb and the cycle Tb (the duty D1 is not changed).

Thereafter, as shown in FIG. 3 (c), the pulse width W
If a pulse current of c, cycle Ta and duty D2 is used, a pulse current having the same frequency as the pulse current of FIG.

In other words, when the duty is changed from FIG. 3 (a) to FIG. 3 (c) in the state where the switching frequency is the same, the frequency is changed lower in the middle and the pulse current as shown in FIG. Fig. 5 (b)
The occurrence of the hysteresis loop characteristic shown in FIG.

In the above embodiment, the valve opening determining means 7 is adapted to determine the valve opening by inputting a signal from the temperature difference detector 6, but it is needless to say that other detectors such as a gas pressure detector may be used. Alternatively, the valve opening may be determined by an operator's keyboard operation or the like.

[Effect of the invention]

As described above, according to the present invention, the correspondence between the duty and the frequency can always be kept at the optimal relation,
When the duty is changed, the hysteresis loop characteristic which has conventionally occurred can be removed, so that the electromagnetic proportional valve can be stably controlled.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIGS. 3 (a) and 3 (b) and FIGS. 3 (a), 3 (b) and 3 (c) are waveform diagrams for explaining the operation of FIG. 1, and FIGS.
5B is a waveform diagram for explaining the operation of the conventional example, and FIGS. 5A and 5B are control characteristic diagrams of the conventional example. 3 ... proportional valve coil, 4 ... switching element (transistor), 5 ... switching element driving means, 7 ... valve opening degree determination means, 8 ... duty adjustment signal output means, 9
... Frequency adjustment signal output means.

Claims (1)

(57) [Scope of request for utility model registration] A switching element is connected to a proportional valve coil, a current flowing through the proportional valve coil is controlled by on / off control of the switching element, and the current control controls the electromagnetic proportional valve to a predetermined opening. In the valve control device, a valve opening degree determining unit that determines an opening degree of the electromagnetic proportional valve based on a predetermined control condition, and when the switching element is turned on / off based on a signal from the valve opening degree determining unit. Duty adjustment signal output means for adjusting the duty of the frequency adjustment signal output means for adjusting the switching frequency of the switching element in response to the adjustment of the duty, based on the duty adjustment signal and the frequency adjustment signal, Switching element driving means for driving the switching element; and The means and the frequency adjustment signal output means, when changing only the duty to the target value without changing the frequency of the pulse signal, temporarily lower the frequency without changing the duty to change the pulse width. After that, the frequency and the pulse width are adjusted so that the duty becomes the target value. An electromagnetic proportional valve control device, characterized in that: