JPH0460288A - Proportional valve drive device - Google Patents

Abstract

PURPOSE:To improve the hysteresis characteristics of a proportional valve by overlapping ripple current on the control signal to control the energized electrical variables of the semiconducting device, which is electrically connected between the proportional valve and a direct current power supply and switching the semiconducting device at a specified frequency. CONSTITUTION:A proportional valve drive device A comprises a transistor 3 electrically connected between a proportional valve 1 and power supply circuit 2. A drive circuit 4 is impressed a ripple overlapping signal 5 at the control terminal 41. Since the proportional valve 1 is driven by energized current overlapped by ripple current, vibrations are given to a plunger and slide resistance becomes small, and hysteresis is eliminated, as a result, the valve opening degree can precisely be determined. In addition, the drive circuit 4 controls a drive transistor 42 so that the voltage at the control terminal 41 may become same as that at a detecting terminal 45 for detecting proportional valve current with a time constant by a capacitor 44 and oscillate at a specified frequency to switch a power transistor 3. The power generates only a little heat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a technology for driving a proportional valve that exhibits an opening degree depending on an energized current.

[Prior Art] Conventionally, proportional valves have been used to maintain the flow rate of fluid at a predetermined value and to keep the secondary pressure constant.

[Problem to be solved by the invention] However, the proportional valve has the following problems due to the sliding resistance of the plunger:
The applied current and, for example, the secondary pressure do not correspond accurately and exhibit hysteresis characteristics.

An object of the present invention is to provide a proportional valve drive device with improved hysteresis characteristics of the proportional valve.

[Means for Solving the Problems] In order to achieve the above problems, the present invention employs the following configuration.

(1) A proportional valve that shows an opening degree according to the energizing current, and a drive circuit that applies a control signal to a control terminal to control the amount of current flowing through a semiconductor element electrically connected between the proportional valve and a DC power supply. In the proportional valve driving device, a ripple having a frequency of 10 Hz or more and 200 Hz or less is superimposed on the control signal, and the first semiconductor element is switched at a predetermined frequency of 500 Hz or more and 10 kHz or less.

(2) Furthermore, the amplitude and frequency of the ripple are varied according to the control signal.

[Operations and Effects of the Invention Regarding Claim 1 (Operations) The proportional valve is driven by an energized current superimposed with ripples having a frequency of 10 hertz or more and 200 hertz or less.

Therefore, vibration is applied to the plunger of the proportional valve, and the sliding resistance is reduced. Here, if the ripple frequency is less than 10 hertz, the proportional valve will constantly vibrate, and if the ripple frequency exceeds 200 hertz, it will not contribute to reducing the sliding resistance.

By switching at a predetermined frequency of 500 hertz or more and 10 kilohertz or less, the semiconductor element generates only a small amount of heat.

Here, if the frequency is less than 500 Hz, the semiconductor element will generate significant heat, and if it exceeds 10 kHz, the semiconductor element will be required for high speed operation, resulting in an increase in cost.

(Effect) The hysteresis of the proportional valve is removed, and the opening degree of the proportional valve can be determined accurately.

The cost can be reduced because the semiconductor element generates less heat and can be used for low frequency and low power consumption.

Regarding claim 2, the proportional valve current is controlled by a control signal. When the proportional valve current is small, the rate of change due to sliding resistance is large, so a large amplitude and low frequency are required, but when the proportional valve current is large, the rate of change due to sliding resistance is small compared to when the proportional valve current is small. It is preferable to remove the vibration of the proportional valve by leaving hysteresis with a small amplitude and high frequency.

In this oval configuration, the ripple amplitude and frequency are varied according to the control signal, so sliding resistance can be removed without rattling the proportional valve.

Note that only one of the amplitude and the frequency may be varied.

[Example] Next, one embodiment of the present invention will be described based on FIG.

The proportional valve drive device A has a power transistor 3 electrically connected between the proportional valve 1 and the power supply circuit 2.

Further, 4 is a drive circuit, and a ripple superimposed signal 5 is applied to its control terminal 41.

The proportional valve 1 includes a coil, a spring, a valve body, and a plunger, and maintains the flow rate of gas at a predetermined amount.

The power supply circuit 2 connects AClooV to a diode bridge 21
and a smoothing capacitor 22 to make it a direct current.

The power transistor 3 is for low frequency and small power use, and the heat sink is small.

The drive circuit 4 includes a power transistor 3, a drive transistor 42, an operational amplifier 43, and a delay capacitor 44.
It is made up of. This drive circuit 4 controls the drive transistor 42 so that the voltage is equal to the control terminal 41 and the detection terminal 45 which detects the proportional valve current with a time constant using a capacitor 44, and oscillates at a frequency of 1 kilohertz. The power transistor 3 is switched.

The ripple superimposed signal 5 is created by combining voltages generated at each port 61 of the microcomputer 60 using a ladder resistor 62 and an operational amplifier 63.

This signal 5 is a proportional valve drive signal 5 as shown in FIG.
This is a step-like electrical signal in which a ripple of 60 to 70 hertz is superimposed on the signal.

Next, the operation of the proportional valve drive device A will be described.

(1) The microcomputer 60 calculates the rotational speed of a combustion fan (not shown) and determines the proportional valve drive signal 51.

(2) The microcomputer 60 outputs the proportional valve drive signal 5
1 is small (for example, 20 mA), the amplitude of the ripple to be superimposed is made small (for example, ±10 mA), and the frequency is made high (for example, 70 Hz).

If the current is large (for example, 200 mA), increase the amplitude (for example, ±15 mA) and lower the frequency (for example, 6
0 hertz).

In addition, according to the program of the microcomputer 60,
The ripple amplitude and frequency are managed to be continuously varied according to the proportional valve drive signal 51.

(3) When this ripple superimposed signal 5 is applied to the drive circuit 4, the power transistor 3 causes a proportional valve current based on the superimposed signal 5 to flow through the coil of the proportional valve 1 while switching at 1 kHz.

Next, the effects of the proportional valve drive device A will be described.

(a) The sliding resistance of the plunger of the proportional valve 1 is reduced by the ripple of 60 to 70 hertz, and the hysteresis of the proportional valve 1 is significantly improved. In addition, 60 hertz ~
A ripple of 70 hertz is most effective in improving hysteresis.

(a) The switching rate of the power transistor 3 is 1 kilohertz. Therefore, a low-power, low-frequency power transistor 3 can be used, and the heat sink can be made small. Note that this switching has a high frequency when viewed from the proportional valve 1, so it has almost no effect on the displacement of the plunger of the proportional valve 1.

(1) Since the ripples are superimposed by the program of the microcomputer 60, the frequency and amplitude of the ripples can be freely selected, and there is no significant increase in cost.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of a proportional valve drive device according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of a ripple superimposed signal in the device.

Claims (1)

[Scope of Claims] 1) The amount of current flowing through a proportional valve that indicates an opening degree in accordance with the energized current, and a semiconductor element that is electrically connected between the proportional valve and a DC power supply by applying a control signal to a control terminal. A proportional valve drive device comprising: a drive circuit for controlling a proportional valve, wherein a ripple having a frequency of 10 hertz or more and 200 hertz or less is superimposed on the control signal, and the semiconductor element is switched at a predetermined frequency of 500 hertz or more and 10 kilohertz or less; A proportional valve drive device characterized by: 2) The proportional valve drive device according to claim 1, wherein the amplitude and frequency of the ripple are varied in accordance with the control signal.