JPS62101981A - Decision circuit for opening and closing condition of solenoid valve - Google Patents

Abstract

PURPOSE:To enable a decision to be surely performed for an opening and closing condition of a solenoid valve, by using a differentiating circuit or the like to extract a change of current waveform, generated in accordance with the DC solenoid valve in its opening and closing, as a simple electric pulse. CONSTITUTION:A characteristic change of current waveform, generated when a DC solenoid valve SV is opened and closed, is extracted as a simple electric pulse by using a differentiating circuit C1 or the like. The DC solenoid valve can be decided to be unable to operate, when said electric pulse is not existent, while to be operated when the electric pulse is existent. The solenoid valve can be further surely controlled by measuring further a time, before the electric pulse is generated, or its peak value to be combined.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an open/close state determination circuit for a solenoid valve that can electrically determine the open/close state of a DC solenoid valve.

(Prior Art and Problems) Automatic and remote combustion of a fuel oxidizer using a sequence controller is commonly performed in combustion-type gas dynamic lasers, liquid rocket motors, torpedoes, boilers, and the like. In this case, in order to immediately detect and avoid dangerous conditions such as ignition failure or malfunction of the fuel oxidizer supply valve (starting valve), some kind of risk prevention measures are incorporated into the sequence controller. For example, it detects the light, temperature, pressure, etc. generated by a flame, and if these amounts do not exceed a certain level, it is determined that some kind of malfunction has occurred, and the sequence is immediately stopped and the fuel oxidizer is supplied. A sequence has been established in which the engine stops, the unburned fuel oxidizer accumulated in the combustion chamber is purged with N2 gas, etc., and a safe state is achieved.

It is also very effective to feed back the opening/closing status of the starter valve into this safety feedback circuit, and this is often done. However, in this case, the opening/closing status can only be fed back when the starting valve has a limit switch built into it and is quite large. This limit switch is mechanically connected to the valve body inside the starter valve that moves when the valve is opened and closed, and although the information from the limit switch is accurate, it is difficult to miniaturize the structure.
It is usually only attached to large pneumatic valves that are operated by air pressure. Other most commonly used solenoid valves are not usually equipped with this limit switch. This is because it is structurally difficult to attach a limit switch to a small solenoid valve that requires high-speed response. , is very effective for preventing danger.

(Means for Solving the Problems) In view of the above points, the present invention makes it possible to reliably detect the open/closed state of a normal DC solenoid valve without a limit switch from the current waveform supplied to the DC solenoid valve. In addition, the present invention aims to provide a circuit for determining the open/closed state of a solenoid valve, which feeds back this information to a sequence controller, thereby making it possible to avoid dangerous situations.

In the present invention, the above-mentioned conventional problems are solved by means of extracting characteristic changes in the current waveform accompanying the opening and closing of a DC solenoid valve as simple electric pulses using a differential circuit or the like.

(Function) In the solenoid valve opening/closing state judgment circuit of the present invention, the characteristic changes in the current waveform accompanying the opening/closing of the DC solenoid valve can be extracted as a simple electric pulse using a differential circuit, etc. If it does not exist, it can be determined that the DC solenoid valve is inoperable, and if an electric pulse is present, it can be determined that the solenoid valve has operated. Furthermore, by measuring the time until the electric pulse is generated or the peak value of the electric pulse, it is possible to control the solenoid valve more reliably.

(Example) Hereinafter, an example of the open/close state determination circuit for a solenoid valve according to the present invention will be described with reference to the drawings.

FIG. 1 shows the #I11 embodiment of the present invention, and FIG. 2 (A)
, (B) are examples of the structure of a DC solenoid valve, and FIG. 3 shows a typical current waveform of the DC solenoid valve.

First, prior to explaining the first embodiment shown in FIG. 1, the structure of a general DC solenoid valve will be explained with reference to FIG. In this Figure 2 (A
) is in the closed state, (B) is in the open state, and when the armature 2 integrated with the valve body 1 is energized to the excitation coil 3,
It moves while being attracted to the excitation coil 3, so that the space between the valve body 1 and the valve seat 4 opens.

The present inventor has discovered that a characteristic change occurs in the current waveform due to the attraction operation of the armature 2 by the excitation coil 3 (that is, the inductance of the fill increases due to the attraction of the armature 2).

The fjS3 diagram shows characteristic changes in the current waveform accompanying the opening and closing of such a DC solenoid valve. When a constant voltage is applied to the solenoid valve at time 1 = 0, the current begins to flow, and the current gradually decreases over time. However, when the excitation coil is magnetized to a certain extent, the current suddenly decreases (section 7 of tJIJ3 diagram), and then increases again to reach a steady current value.

The important point here is that in the 7th part where the current suddenly decreases,
This shows that the valve body in the solenoid valve has moved (the armature has been attracted to the excitation coil), that is, it has been mechanically operated, and the decrease in the current value in parentheses and the movement of the valve body is 1.
The inventor has discovered and confirmed that there is a one-to-one relationship. In other words, if the valve body in the solenoid valve does not move even if a current is applied for some reason, the characteristic change as shown in section 7 in Figure 3 will not occur, and as shown by the dotted line in Figure 3, The current waveform is monotonically increasing.

The above-mentioned characteristic change in the current waveform accompanying the opening and closing of the solenoid valve is exactly the part A in Figure 3, and if there is this characteristic change,
It can be determined on a one-to-one basis that the solenoid valve has been mechanically operated from the current waveform. This information is fed back to the sequence controller, and if there is no characteristic change, current is being supplied to the solenoid valve, but it is not mechanically operating.

In other words, it is possible to determine that a malfunction has occurred and perform some kind of combustion control using the sequence controller.

The presence or absence of a characteristic change in the current waveform accompanying the opening and closing of this solenoid valve can be easily determined by visually observing the current waveform using a synchronized course or the like. It is also possible to extract this characteristic change by inputting the current waveform into a spectrum analyzer. However, such methods require human intervention or require very expensive measuring instruments, making them impractical.

The characteristic change in the current waveform (part A in FIG. 3) accompanying the opening and closing of the solenoid valve is significantly different from other parts of the current waveform. This is because the temporal change in current is very large in the 7th part and has a negative value.

Extracting only this characteristic change is easily possible by differentiating the current waveform with a capacitor or inductance.

The fpJ1 embodiment shown in FIG. 1 uses a differentiating circuit using a capacitor to extract characteristic changes in the current waveform. In this figure, a DC solenoid valve S■ is connected to a DC power source PW via a switch S and a resistor R. Here, the resistor R is a resistor for detecting the current waveform, and is usually selected to have a sufficiently small value so that voltage loss is small. Capacitor C
1 differentiates the current waveform.

The current waveform in Figure 3 is the voltage waveform between the ground and point a of the circuit in Figure 1, but if this is passed through capacitor C1 and differentiated, the voltage waveform between the ground and point b becomes the waveform shown in Figure 4. become. That is, by differentiating the characteristic change in the current waveform accompanying the opening and closing of the solenoid valve, it becomes as shown in part A of the fjS4 diagram.

Part A in Figure 4 is quite different from the others. This is a fairly large and sharp negative pulse, and if this pulse does not occur, a malfunction can be determined using a commonly used simple circuit, and the sequence can be easily controlled.

In the embodiment shown in FIG. 1, a low-pass filter LF and a comparison circuit COM are provided after the capacitor C1, and the sequence controller C0NT is connected through these.

The low-pass filter LF is connected to a solenoid valve drive switch S.
This is not necessary if a non-chattering switch such as a solid state relay is used, but with a microswitch, a fairly large positive and negative pulse (relatively high frequency) is observed at point b in Figure 1 when the voltage is turned on. However, it is used to take this pulse. Further, the comparator circuit COM outputs, for example, an operation detection signal of about 5 parts when the peak value of PIl, part A in FIG. 4, is above a predetermined value.

Sequence control? 1 in CON T If a function equivalent to this comparison circuit exists, it can be omitted.

The second embodiment shown in FIG. 5 uses an inductance-based differentiation circuit to extract characteristic changes in the current waveform. In this figure, a DC solenoid valve S■ is connected to a DC power source PW via a switch S and a coil (inductor) L+. A coil (inductor) L2 is electromagnetically coupled to the fill L1.

A current of the electromagnetic valve flows through the fill L1, and a differential waveform of the current flowing through the fill L1 appears in the coil L2 coupled thereto by electromagnetic induction. The voltage waveform produced at L2 is similar to that in FIG. 1 using a capacitor, and the movement of the valve body of the solenoid valve provides a distinctly different pulse. The fact that the obtained pulses can be fed back to the sequence controller and easily used as control signals is
This is the same as in the case of the capacitor.

Compared to the h1 configuration using a capacitor, the configuration using the mutual induction coil shown in FIG. There are advantages that by increasing the number of windings, a sufficiently large voltage can be obtained without the need for amplification.

Note that the capacitor c2 in Figure #IJ5 resonates between L2 and c2 to more efficiently extract characteristic changes in the current waveform accompanying the opening and closing of the solenoid valve.

As in the case of the capacitor differential circuit, there is no need to create resonance if the solenoid valve drive switch S is non-chattering, but when the switch S has chattering, the characteristics of the chattering frequency and current waveform This method takes advantage of the fact that the frequencies of change are different and that only the latter signal can be extracted efficiently. Also,
A comparison circuit COM is arranged between the sequence controller and the sequence controller, if necessary.

Figure 6 shows how the current waveform of a solenoid valve changes with changes in the fluid pressure applied to the solenoid valve.As the load is applied (as the fluid pressure increases), the current waveform changes. The position at which the characteristic change appears is gradually delayed, and the rate of change of the current over time also decreases. That is, the electric pulses extracted in the WSL of the present invention and in the second embodiment are generated later and their height becomes lower as the fluid pressure applied to the solenoid valve increases.

Therefore, it is possible to effectively utilize the above physical phenomenon and control the solenoid valve more effectively. That is, in the first and second embodiments, only the presence or absence of a characteristic change in the current waveform accompanying the opening and closing of the DC solenoid valve is fed back to the sequence controller, but the It is possible to feed back the time or its strength to the sequence controller, process this information within the sequence controller, and control the solenoid valve more effectively. That is, a set value is set for a certain set time or pulse height, and if a pulse does not arrive by the set time, malfunction is approaching.

Alternatively, if a pulse higher than the set height does not arrive, it can be determined that malfunction is approaching, and the solenoid valve can be controlled more effectively within the sequence controller.

Note that time can be measured using a counter or the like, and pulse peak values can be measured by providing a plurality of comparison circuits or the like.

(Effects of the Invention) As explained above, the present invention can determine the open/close state of a normal DC solenoid valve from its current waveform, extract the open/close state with a simple circuit, and convert it into an electric pulse. . Therefore, the pulse can be fed back to the sequence controller to control the solenoid valve, and it is possible to effectively control a normal solenoid valve without a limit switch without making any changes to the solenoid valve. By using the present invention, it is possible to prevent dangerous situations due to malfunction of the starter valve or the like.

[Brief explanation of drawings]

FIG. 1 shows $1 of a circuit for determining the open/closed state of a solenoid valve according to the present invention.
A circuit diagram showing the embodiment, Figure 2 (A) is a structural diagram with the solenoid valve closed, Figure 2 (B) is a structural diagram with the solenoid valve open, and Figure 3 is the power-on of the DC solenoid valve. FIG. 4 is a waveform diagram showing the voltage waveform between the ground and point b in FIG. 1 (corresponding to the differential waveform of the waveform in FIG. 3), and FIG. , a circuit diagram showing the second embodiment, and FIG. 6 is a waveform diagram showing changes in current waveform due to fluid pressure applied to a solenoid valve. S■...Solenoid valve, S...Switch, PW...DC power supply, R...Resistor, C,, C2...Capacitor, L
,, L2... fill, LF... low pass filter,
COM... Comparison circuit.

Claims (4)

[Claims] (1) A circuit for determining the opening/closing state of a solenoid valve, which is characterized by extracting characteristic changes in the current waveform accompanying the opening/closing of a DC solenoid valve as electric pulses. (2) A circuit for determining the opening/closing state of a solenoid valve according to claim 1, which extracts the electric pulse by passing the current waveform of the DC solenoid valve through a differentiation circuit using a capacitor or after that through a low-pass filter. . (3) The circuit for determining the opening/closing state of a solenoid valve according to claim 1, wherein the electric pulse is extracted by passing the current waveform of the DC solenoid valve through an electromagnetic induction coil or a resonance coil. (4) The electromagnetic valve according to claim 1, 2 or 3, which measures the time until the electric pulse is generated or the peak value of the electric pulse while extracting the electric pulse. Open/close status judgment circuit.