JP2004117170A - Solenoid valve control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To implement a simple and inexpensive solenoid valve control circuit for electrically detecting the closed or open state of a solenoid valve and improving safety. <P>SOLUTION: On the basis of current value differences due to the locational relation between a solenoid 15 and a movable iron core 16 when a dive current is passed through the solenoid valve 11 by an element 3 for drive, the closed or open state of the solenoid valve 11 is detected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solenoid valve control circuit, and more particularly to a circuit for detecting the open / closed state of a solenoid valve of a gas meter or gas appliance.
[0002]
[Prior art]
The solenoid valve of a gas meter or gas appliance flows gas in an open state and shuts off gas in a closed state. However, when it is not possible to shift from the open state to the closed state due to a failure such as sticking, the risk of a gas accident increases due to outflow of gas. For this reason, the gas meter regularly and manually shuts off the test to ensure its safety. Further, in a gas appliance, two solenoid valves are provided in series to make them redundant, and their safety is maintained.
[0003]
The gas meter has a battery-free specification for 10 years, and a self-holding solenoid valve or a motor valve is used to save current. This solenoid valve normally keeps the gas passage open by a permanent magnet, and when there is an abnormality such as gas leakage, a current flows for a moment (several tens of milliseconds) in the direction opposite to the direction of opening by the permanent magnet to extinguish the magnetic force and reduce the spring pressure. To close the gas. Therefore, unlike the solenoid valve of the gas appliance, no current is required to the solenoid during opening.
[0004]
[Problems to be solved by the invention]
However, in the gas meter, the test shutoff is performed by a magnet reader by a magnet at the time of gas inspection or the like to check whether the test is normal or not. In recent years, automatic meter reading has been performed, and the number of times of automatic meter reading is almost nil.
[0005]
Although gas appliances are designed redundantly, even if one of them fails, it will not be found even if it fails, and the probability of failure of one more cannot be said to be zero.
[0006]
[Means for Solving the Problems]
The present invention utilizes the fact that the solenoid changes its electrical measurement value at the position of the movable iron core in order to solve the above problem, and confirms whether the solenoid valve has shifted from open to closed or from closed to open. It has a means for measuring a change over time in electrical characteristics.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The solenoid valve control circuit according to claim 1 of the present invention has a detection circuit that detects the open / closed state of the solenoid valve by causing a drive current to flow through the solenoid drive element.
[0008]
The electronic valve control circuit according to claim 2 of the present invention has a detection circuit for detecting the open / closed state of the solenoid valve when the movable iron core moves. The solenoid valve control circuit according to claim 3 of the present invention has a detection circuit for detecting the open / closed state of the solenoid valve before the shutoff valve shuts off. An electromagnetic valve control circuit according to a fourth aspect of the present invention has a detection circuit for detecting an open / closed state of the electromagnetic valve by detecting a current equal to or greater than a current calculated by the DC resistance of the solenoid. The solenoid valve control circuit according to claim 5 of the present invention has a detection circuit for detecting a current immediately after the current of the solenoid is stopped. The solenoid valve control circuit according to claim 6 of the present invention has a detection circuit for differentiating the current immediately after the current to the solenoid is started to detect the open / close state of the solenoid valve. The solenoid valve control circuit according to claim 7 of the present invention has a detection circuit for detecting the open / closed state of the solenoid valve by differentiating the current immediately after the current to the solenoid is stopped. The solenoid valve control circuit according to claim 8 of the present invention has a detection circuit for measuring a voltage immediately after the current to the solenoid is stopped. The detection circuit for detecting the open / closed state of the solenoid valve can automatically detect a failure of the gas meter or the gas appliance, thereby improving safety.
[0009]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
(Example 1)
1 and 4 are circuit diagrams showing an embodiment 1 of the present invention. FIG. 2 is a structural view of the solenoid valve, and FIGS. 3 and 5 show waveform diagrams during operation of the solenoid valve.
[0011]
In FIG. 1, reference numeral 1 denotes an electromagnetic valve control circuit of a gas meter, 2 denotes a battery, 3 denotes a cutoff transistor as a driving element, 4 denotes a microcomputer having a built-in detection circuit for detecting the open / close state of the electromagnetic valve, and 5 denotes a test. A shut-off switch, 6 is a gas meter main body, 7 is a flow sensor, 8 is a gas appliance, 9 is a gas cylinder (container), 11 is a solenoid valve, and 10 is a current detecting resistor. Further, the structural view of the solenoid valve in FIG. 2 shows an open position, 12 is a permanent magnet, 13 is a fixed iron core, 14 is a yoke (yoke), 15 is a solenoid (winding), 16 is a movable iron core, and 17 is a spring. Is shown.
[0012]
FIG. 3 shows a current waveform diagram when the solenoid valve is shut off. A is a waveform when current is applied to the solenoid valve when the solenoid valve is open and fixed, B is a waveform when current is applied to the solenoid valve when closed, and C is a waveform when the current is changed from open to closed. Show.
[0013]
FIG. 4 shows a detection circuit for detecting the open / closed state based on the voltage of the solenoid. FIG. 5 shows the voltage change of the solenoid when the drive current flows through the solenoid valve and when the drive current ends. D is a voltage waveform when normally closed, and E is a voltage waveform when fixed in an open state.
[0014]
The operation will be described with reference to FIGS. Usually, the gas from the gas cylinder 9 is supplied to the gas appliance 8 through the gas meter 6. The microcomputer meter detects the gas flow rate with the flow rate sensor 9 and closes the solenoid valve 11 when the flow rate pattern is abnormal to prevent a gas accident. The solenoid valve 11 causes a current to flow through the shutoff transistor 3 for about 40 ms to shut off the gas. The solenoid valve 11 is a self-holding type, and normally (open), the movable iron piece 16 is attracted to the fixed iron core 13 by the magnetic force of the permanent magnet 12, and the transistor 3 is in an off state. At the time of shut-off, a current flows through the solenoid 15 by the transistor 3 to temporarily eliminate the magnetic force of the permanent magnet 12 and close by the spring pressure of the spring 17 to shut off the gas.
[0015]
Next, the current based on the positional relationship between the solenoid and the movable iron core will be described with reference to FIG. A is the waveform when current is passed through the shut-off valve when the solenoid valve is open and stuck. In this case, since the distance between the solenoid and the movable iron core is long, the inductance of the solenoid is low and the current rises quickly. Become. B is a waveform when a current flows through the solenoid valve when the solenoid valve is closed and fixed, and this waveform is obtained because the distance between the solenoid and the movable iron core is short. C is a waveform when the opening and closing are normally performed. The movable iron core is initially close to the solenoid, but then becomes longer, and at the moment when it is further closed, the movement is stopped by the valve seat. It becomes. In the present invention, in consideration of these waveform characteristics, it is possible to determine whether the operation is normal by observing these current values at the detection port a of the microcomputer approximately 8 ms after the current is started by the cutoff transistor 3. That is, if the value at this time is 150 mA or more, it can be determined that the solenoid valve is fixed.
[0016]
Further, the difference can be clarified more remarkably by differentiating the waveforms of A and B. The differentiating circuit is not shown, but can be easily configured by inserting a capacitor in series. Although the saturation current at the time of cutoff is 195 mA in the calculation of the DC resistance, a current of 200 mA or more is observed due to the transient characteristics of normal operation. Therefore, if a current of 200 mA or more is not observed at the port a at the maximum, it is determined that the wire is fixed or disconnected.
[0017]
Next, a description will be given with reference to FIGS. FIG. 4 is a circuit for directly measuring the voltage of the solenoid. The voltage of the solenoid becomes D when it is normal, but becomes E when it is fixed. This is because, in the case of sticking, since the amount of charge stored is large while the distance between the solenoid and the movable iron core is short, the time required for discharging when the current of the solenoid disappears becomes longer. Therefore, it can be determined whether or not the voltage is normal by confirming whether there is a negative voltage at 10 ms after the solenoid valve current is turned off. If a negative voltage is observed at the port a, the solenoid valve is not closed.
[0018]
In the present embodiment, the detection circuit is directly performed by a microcomputer, but can naturally be configured by a transistor, a comparator, or an FET. The solenoid valve may be a motor valve.
[0019]
【The invention's effect】
As described above, the solenoid valve control circuit according to claim 1 of the present invention can check whether the solenoid valve operates normally by passing the original drive current by the drive element of the solenoid. It is simple, simple and inexpensive to implement.
[0020]
Since the solenoid valve control circuit according to the second and third aspects of the present invention can detect an abnormality before the movable iron core moves from open to closed, the abnormality can be identified without operating the electromagnetic valve. Therefore, in the case of gas meters, etc., the safety was previously checked manually by test shut-off.However, the test shut-off can be automatically performed regardless of whether the user is using the gas, and the safety is periodically and unmanned. Can be secured. Automatic meter reading is also possible.
[0021]
Since the solenoid valve control circuit according to the fourth aspect of the present invention observes only the maximum current, abnormality can be determined regardless of the operation time of the solenoid valve by observing all of the solenoid valve during driving, for example, for 40 ms.
[0022]
The solenoid valve control circuit according to claim 5 of the present invention performs the determination after stopping the current, and the microcomputer processing can be performed after the shut-off operation to allow a margin, and after stopping the gas in the solenoid valve such as a gas appliance, It can be determined whether the valve has been closed reliably.
[0023]
The solenoid valve control circuit according to claims 6 and 7 of the present invention can obtain a larger signal as a signal by differentiating the current gradient of the applied current and look at the waveform, regardless of the movement time variation of the movable iron core. An abnormality can be determined. In addition, by differentiating the falling current, it is possible to use the gas appliance as described above.
[0024]
Since the solenoid valve control circuit according to claim 8 of the present invention directly detects a voltage, a current conversion resistor is not required unlike the current detection. In general, a solenoid valve driven by a battery voltage requires a current and thus has a low resistance, but the loss is large due to the resistance. According to this, an abnormality can be detected without increasing the number of parts and without impairing the drive loss.
[Brief description of the drawings]
1 is a configuration diagram of a solenoid valve control circuit according to a first embodiment of the present invention; FIG. 2 is a structural diagram of a solenoid valve driven by the circuit; FIG. 3 is a current waveform diagram during operation of the solenoid valve; FIG. 5 is a circuit diagram showing a part of the circuit. FIG. 5 is a voltage waveform diagram of the solenoid valve during another operation.
1 Solenoid valve control circuit 3 Transistor (drive element)
4 Microcomputer (detection circuit)
11 Solenoid valve 15 Solenoid 16 Movable iron core

Claims (8)

A solenoid valve that shuts off the passage, a solenoid of the solenoid valve that shuts off the flow path, a movable iron core that changes its position by the current of the solenoid, a driving element that supplies current to the solenoid, and An electromagnetic valve control circuit, comprising: a detection circuit for detecting a position of the movable iron core when a current flows. 2. The solenoid valve control circuit according to claim 1, wherein when the movable iron core is moved by a current of the driving element, a position of the movable iron core is detected by a detection circuit. 3. The solenoid valve control circuit according to claim 1, wherein the solenoid valve is a self-holding type, and the position of the movable iron core is detected by a detection circuit after the drive length of the solenoid valve. The solenoid valve according to any one of claims 1 to 3, wherein the position of the movable iron core is detected by flowing through the solenoid a current equal to or greater than a current value calculated by the solenoid applied voltage and the solenoid DC resistance immediately after the solenoid valve is driven. Control circuit. The solenoid valve control circuit according to claim 1, wherein the solenoid current is detected immediately after the current to the solenoid is stopped. 6. The solenoid valve control circuit according to claim 1, wherein a position of the movable iron core is detected by differentiating a current immediately after the current is supplied to the solenoid. 7. The solenoid valve control circuit according to claim 1, wherein the position of the movable iron core is detected by differentiating the current immediately after the current to the solenoid is stopped. The solenoid valve control circuit according to any one of claims 1 to 7, wherein the position of the solenoid is detected by detecting a voltage immediately after the current to the solenoid is stopped.

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