JPH039272A - Operation state detecting device for solenoid - Google Patents

Abstract

PURPOSE:To improve the detection accuracy and releability by detecting the operation state of the solenoid from the phase difference between an AC signal which is inputted to the coil of the solenoid and its output AC signal. CONSTITUTION:When a cut-off valve is closed, a CPU 9 outputs a valve opening control signal with an external signal. A valve driving circuit 6 holds its output terminal (c) at H level and its output terminal (d) at L level and supplies a DC valve opening driving current to the latching coil L of the solenoid from the terminal (c) to the terminal (d) for a specific time, so that the cut-off valve is opened. Then when an answer-back strobe signal is outputted for a specific time, a sine wave transmitter 7 begins to oscillate and output a sine wave current for a specific time and also turns on switches SW1 and SW2. The current flows to the coil L and a detection resistance R1 and a phase difference detecting circuit 8 compares voltage of xy and yz and outputs an answer-back signal to CPU 9 when the difference exceeds a specific quantity to confirm the operation state of the solenoid. When the valve is closed, the phase differ ence is detected to confirm the operation state of the solenoid similarly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an operating state detection device for a solenoid, and more specifically, it is used to operate, for example, an on-off valve, a switching valve, etc., and maintain it in that state. The present invention relates to a solenoid operating state detection device that detects the operating state of a solenoid such as a latching solenoid.

[Prior Art] Generally, when operating an on-off valve or a switching valve, a solenoid drive circuit drives the latching solenoid by passing a drive current through the latching solenoid in response to the input of an on-off control signal or a switching control signal. The valve is operated by driving a latching solenoid.

In such a case, the valve may not be activated even if a control signal is input, so it is necessary to confirm whether the valve has been reliably activated after the control signal is input.

Conventionally, in order to check this valve operation, a reed switch was installed in the leakage magnetic flux generated by the latching solenoid, and the fact that the leakage magnetic flux varied depending on the operating state of the latching solenoid was used to control the reed switch on and off. A solenoid operating state detection device is used which generates an answerback signal indicating the operating state of the latching solenoid.

[Problem to be solved by the invention]

However, in the configuration of the conventional solenoid operating state detection device described above, an answerback signal is generated by driving the reed switch on and off depending on the magnitude of leakage magnetic flux, so the magnetic flux that causes the contact piece of the reed switch to approach and separate is If there are variations in the level, it will not be possible to reliably answer back the operating status of the solenoid, so it will be necessary to delicately adjust the installation position of the reed switch. In particular, in the case of a solenoid with improved efficiency, i.e. performance, the leakage magnetic flux is extremely small, so the reed switch can be turned on and off as described above.
The inaccuracy of the off operation becomes increasingly noticeable. Furthermore, since the reed switch has a mechanical contact piece, there is a problem in that reliability is poor, such as a high possibility of failure due to wear of the contact piece.

Therefore, it is an object of the present invention to provide a novel solenoid operating state detection device that can reliably detect the operating state of a solenoid without requiring troublesome adjustments and has improved reliability.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a solenoid operating state detection device that provides a solenoid operating state detecting device that drives a movable piece of a solenoid from a first state to a second state, or from a second state to a first state, respectively. The solenoid operating state detection device detects the operating state of the solenoid after the first or second drive current is passed through the solenoid coil, An AC signal output means for passing an AC signal through the coil; and a phase difference detection means for detecting a phase difference between the AC signal flowing through the coil of the solenoid and the AC signal output from the AC signal output means. It is characterized in that the operating state of the solenoid is detected based on the phase difference detected by the phase difference detection means.

(Function) In the above configuration, the movable piece of the solenoid is moved from the first to the second
After passing the first or second drive current to the coil of the solenoid to drive the solenoid to the state or from the second to the first state, an alternating current signal is caused to flow from the alternating current signal output means to the coil of the solenoid. We focused on the fact that the phase of the AC signal flowing through the solenoid's coil lags behind the original AC signal due to its inductance component, and that the amount of phase lag depends on the loss coefficient, which changes depending on the operating state of the solenoid. Then, the phase difference detection means detects a phase difference between the AC signal flowing through the coil of the solenoid and the AC signal output from the AC signal output means, and the operating state of the solenoid is determined based on the detected phase difference. I'm trying to detect it.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit block diagram showing one embodiment of the solenoid operating state detection device according to the present invention. Before describing this embodiment, the operating principle of the present invention will be explained with reference to FIG. 2.

FIG. 2 shows an example of the gas cutoff valve 1. In the figure, the gas cutoff valve 1 includes a latching solenoid 10, a valve body 11 operated by the latching solenoid 10, and a valve opened and closed by the valve body 11. Hole 12. A valve seat 12 having
It is composed of. Further, the latching solenoid 10 is coiled and the movable piece 10. and a magnet Mg, and a movable piece 10. The valve body 11 is integrally provided with the valve body 11 . When the valve body 11 is in contact with the valve seat 12, the gas cutoff valve 1 opens the valve hole 12. is closed and the valve is closed (
(left side in Figure 2), and when they are not in contact, the valve hole 12
1 is opened and the valve is in the open state (right side in Figure 2).

In the above configuration, when the valve body 11 is in the valve closed state in contact with the valve seat 12, the latching valve 1
When a DC valve opening current is applied to the coil L of 0, the movable piece 10. is excited. This excited movable piece 10. When the direction of the valve opening current is set so that the magnetic pole of the magnet Mg is different from the magnetic pole of the magnet Mg, the movable piece 10 is attracted to the magnet Mg, thereby the valve body 11 is separated from the valve seat 12 and the valve is opened.

Furthermore, when a DC valve closing current in the opposite direction to the valve opening current is applied to the coil L from the valve open state, the movable piece 101 is excited to have the same magnetic pole as the magnetic pole of the magnet Mg. A repulsive force acts between the attracted movable piece 101 and the magnet Mg, causing the movable piece 10. moves, and the valve body 11 comes into contact with the valve seat 12, resulting in the valve being in a closed state.

In addition, when the latching solenoid 10 transitions from the valve open state to the valve closed state or from the valve closed state to the valve open state, the latching solenoid 10 flows the valve open drive current and the valve open drive current for a predetermined period of time, and then does not need to flow the drive current. , so that the valve body 11 can be maintained (latched) in that state.

Now, considering the inductance of the coil L of the latching solenoid 10, the movable piece 1 when the valve is closed.
0. The magnetic coupling between the coil L and the coil L is larger than the magnetic coupling when the valve is open.

Therefore, since the former magnetic flux is larger than the latter magnetic flux,
The inductance of the coil L when the valve is closed is greater than the inductance when the valve is open.

Looking at this from the perspective of loss coefficient, D = 1/Q, and Q = R/ωL, (R: DC resistance of coil L, ω: angular frequency, Lo: inductance of coil L). , the loss coefficient when the valve is open is larger than the loss coefficient when the valve is closed.

Therefore, the valve closing drive current and the valve closing drive current are supplied to the coil L to move the movable piece 10. When a sinusoidal AC current is passed through the coil as an AC signal after driving the coil, the loss coefficient becomes a composite vector of the current i due to the DC resistance R and the current i due to the coil as shown in FIG. Therefore, as shown in FIG. 4, the phase of the sine wave alternating current 11 flowing through the coil I is delayed with respect to the original sine wave alternating current 10, resulting in a time delay Δt.

At this time, as mentioned above, the loss coefficient is larger when the valve is open than when it is closed, so the phase lag (
time delay) is greater than the phase delay in the valve closed state. Therefore, by detecting and determining the phase lag between the valve opening and the valve closing with respect to the original sine wave alternating current, it is possible to determine whether the solenoid 10 is driven and the valve is opened or closed. can be known.

Note that the inductance component of the coil changes depending on the temperature, but this change is small compared to the change in the inductance component when the valve is opened and closed, and the direct current of the coil changes in the same direction as the change in the inductance component depending on the temperature. Since the resistance component is also changing, the effect of temperature change can be ignored.

Returning to FIG. 1, one embodiment of the solenoid state detection device according to the present invention will be described. In the figure, a valve drive circuit 6 is connected to both ends of a coil L of a latching solenoid 10, and a detection resistor R5 is connected to the coil. are connected in series. A sine wave oscillator 7 serving as an AC signal output means for outputting a sine wave current as an AC signal is connected to both ends of the series-connected coil L and detection resistor R1 via analog switches sw, , sw. Analog switch SWl
The one end X of the coil L connected to the coil L, the interconnection point y of the coil L and the detection resistor R1, and the one end 2 of the detection resistor R1 connected to the analog switch SW2 are connected to the phase difference detecting means. It is connected to the input of the detection circuit 8.

Note that one end Z of the detection resistor R1, that is, the sine wave oscillator 7
The line connected to via the analog switch SW2 is set as a reference potential (earth).

The input of the valve drive circuit 6, the output of the phase difference detection circuit 8, the control input of the sine wave oscillator 7, and the analog switch sw.
A control terminal of sw is connected to the CPU 9. The CP
U9 outputs valve open and valve close control signals to the valve drive circuit 6, and inputs the output (answer back signal) of the phase difference detection circuit 8 to determine whether the valve is open or closed. Furthermore, an answer back strobe signal is output to the sine wave oscillator 7 and the analog switches sw, swz, and the answer back strobe signal controls the sine oscillator 7 to start and stop, and also controls the on/off of the analog switches SW+ and SW2. I do.

In the above configuration, the operation of the CPU 9 is shown in FIG.
A flowchart diagram showing the work performed by
) to (b) will be explained with reference to waveform diagrams of each part.

In the first step S1, the CPU 9 outputs a valve opening control signal (FIG. 7(a)) or a valve closing control signal (FIG. 6(c)) to the valve drive circuit 6. The CPU 9 determines which control signal to output based on a signal input from the outside. Now, gas cutoff valve 1 is in the valve closed state, and C
Assume that PtJ9 outputs a valve opening control signal (FIG. 6(a)). The valve opening control signal outputted by the CPU 9 is sent to the valve drive circuit 6.
In response to this, the valve drive circuit 6 sets its output terminal C to an H level and its output terminal d to an L level, and causes the coil of the latching solenoid 10 to move in the direction from the output terminal C to the output terminal d. A DC valve opening drive current (FIG. 6(C)) is applied for a predetermined period of time. As a result, the movable piece 10I is driven as described above, and the gas cutoff valve 1 is opened (
Figure 6(e)).

Next, proceed to step S2 1. The answer back strobe signal is output for a predetermined time (FIG. 6(f)), and the answer back strobe signal starts the oscillation of the sine wave oscillator 7 to output a sine wave current for a predetermined time, and the analog switches sw, , s , is turned on for a predetermined period of time. This allows the sinusoidal current to flow through the analog switches sw, , sw
2 to the coil L and detection resistor R1. The sinusoidal currents before and after flowing through the coil are determined by the voltage VX at one end of the coil L (Fig. 6 (6)) and the voltage v across the detection resistor R.
y□ (FIG. 6(h)). The detected voltage ■X□ (6th output)) and the detected voltage vy-
(The phase difference detection circuit 8 to which Fig. 6 (cloudy) is input compares the phases of both, detects whether the phase difference is more than a predetermined amount, and outputs an answer bank signal according to the detection result. do.

After executing step S2, the CPU 9 proceeds to step S3,
Read the answer back signal from the phase difference detection circuit 8,
In the following step S4, it is determined based on the read answerback signal whether the gas cutoff valve 1 is in the open state.

The above-mentioned operation has been explained for the case where the CPU 9 outputs the valve opening control signal in step S1, but in step S
When the valve closing control signal is output in step 1, the operation is as follows.

The valve drive circuit 6 receives the valve closing control signal (FIG. 6(b)) from the CPU 9, and sets the output terminal d to the H level and the output terminal C to the L level, contrary to the case described above, and controls the solenoid 10. A DC valve closing driving current (FIG. 6(d)) is applied to the coil from the output terminal d to the output terminal C for a predetermined period of time. As a result, the movable piece 101 is driven as described above, and the gas cutoff valve 1 is brought into the closed state (FIG. 6(e)). Next, the process proceeds to step S2, where the answer back strobe signal is output for a predetermined time (see Figure 6)), the sine oscillator 7 starts oscillation to output a sine wave current for a predetermined time, and the analog switches SW+ and SWz are turned on for a predetermined time. turn on. The sine wave current is applied to an analog switch SW.

, SW2 to the coil L and detection resistor R1.

The sinusoidal currents before and after flowing through the coil are determined by the voltage V, xz at one end of the coil L (Fig. 6 ((to)) and the voltage Vy, (Fig. 6 (h)) across the detection resistor R5. A phase difference detection circuit 8 to which the detected voltage VX2 (FIG. 6 (h)) and the detected voltage V (FIG. 6 (6)) are input compares the phases of the two. Then, it detects whether the phase difference is greater than or equal to a predetermined amount, and outputs an answerback signal according to the detection result.

After executing step S2, the CPU 9 proceeds to step S3,
Read the answer back signal from the phase difference detection circuit 8,
(In step S4, it is determined whether the gas cutoff valve 1 is in the open state based on the read answerback signal.

As shown in Figure 6 ((2), peak), the sine wave current flowing through the coil has a phase lag with respect to the original sine wave current, but the phase of the detected voltage VyH with respect to the voltage V XIE in the valve open state is The delay (time delay) Δt1 is larger than the phase lag Δt2 in the valve closed state.

Therefore, the phase difference detection circuit 8 detects the phase difference between the valve open state and the valve closed state, and outputs different answer back signals in both states. Based on this answerback signal, the CPU 9 determines whether the gas cutoff valve 1 has entered the valve open state or valve closed state after outputting the valve open control signal or the valve close control signal.

FIG. 7 shows a specific circuit example of the phase difference detection circuit 8. In the same figure, the level comparator 81 has a sine wave voltage (2) of the sine wave current before being passed through the coil.

and the reference voltages set by resistors R2 and R3 are respectively input, and the level comparator 82 receives the detection voltage vy2 detected by the detection resistor R3 of the sinusoidal current passed through the coil, and the resistors R4 and Rs. The reference voltages set by are respectively input. The output of the level comparator 81 is passed through a delay circuit 83 to an R8-flip-flop 84 (hereinafter R3
-FF), and the output of the level comparator 82 is directly input to the reset terminal of R3-FF84. An answer back signal is output to the output Q of 1R3-FF84.

The delay time of the delay circuit 83 is set to be equal to the phase difference (Δtz in FIG. 6(C)) between the sine wave current flowing through the coil in the valve closed state and the original sine wave current.

In the above configuration, its operation is shown in Fig. 8(a) to (f).
This will be explained with reference to waveform diagrams of each part. Level comparator 81.
82 contains the sinusoidal voltages V Xil and v
y- (FIGS. 8(a) and 8(b)) are respectively inputted and compared with the reference voltages, so that the sine wave voltage Vxi is applied to the output of the level comparator 81 and 82.
A pulse signal corresponding to the period of p V yz is output (FIGS. 8(C) and (d)). The output from the level comparator 81 is delayed by Δt2 by the delay circuit 83 (FIG. 8(e)). Therefore, in the valve closed state, the pulse signal that has passed through the delay circuit 83 and the pulse signal based on the voltage across the detection resistor R output from the level comparator 82 are in phase, and both pulse signals are connected to the set terminal of R3-FF84. and are input to the reset pin at the same time. Therefore, the output Q of R3-FF maintains the L level, and an answer back signal at the L level is output (see Fig. 8).

On the other hand, in the valve open state, the phase difference Δt between the pulse signal from the level comparator 81 and the pulse signal from the level comparator 82 is sufficiently larger than Δt2, so the delay time Δ
A phase difference Δm3 still exists between the pulse signal from the level comparator 81 and the pulse signal from the level comparator 82 that have passed through the delay circuit 83 at t2 (
Figure 8(e)). Therefore, R3-FF84 first receives the pulse signal from the delay circuit 83 to its set terminal and enters the set state, and then after ΔL3, the pulse signal from the level comparator 82 enters the reset terminal and enters the reset state again. . Therefore, in the valve open state, the output Q of R3-FF 84 outputs an answerback signal that is at H level for a certain period of time (FIG. 8(f)).

In addition to sine waves, rectangular waves and triangular waves can be considered as the alternating current supplied to the coil, but since such waveforms have a rapid or constant rate of change over time,
It is desirable to use a sine wave current because it is difficult to cause a phase lag in the alternating current flowing through the coil with respect to the original alternating current, making it difficult to determine the phase difference for detecting the valve open state and valve closed state.

The frequency of the sine wave current is appropriately set depending on the structure of the magnetic circuit of the solenoid 1o.

〔effect〕

As explained above, according to the present invention, the phase of the AC signal flowing through the solenoid coil lags behind the original AC signal due to its inductance component, and the amount of phase delay changes depending on the operating state of the solenoid. Focusing on the fact that it depends on the coefficient, the phase difference between the AC signal flowing through the solenoid coil and the original AC signal is detected, and the operating state of the solenoid is detected based on the detected phase difference. Therefore, detection accuracy and reliability can be improved without requiring troublesome adjustment of the operating state of the solenoid.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of the solenoid operating state detection device according to the present invention, FIGS. 2 to 4 are explanatory diagrams for explaining the operating principle of the present invention, and FIG. Flowchart diagram showing the work performed by the CPU in the figure, Figure 6 is a diagram showing waveforms of each part in Figure 1, Figure 7 is a circuit diagram showing a specific circuit configuration of a part of Figure 1, Figure 8 7 is a diagram showing waveforms at various parts in FIG. 7. FIG. 7... Sine wave oscillator (AC signal generation means), 8...
Phase difference detection circuit (phase difference detection means), 10... latching solenoid (solenoid), L... coil.

Claims (1)

[Claims] A solenoid after a first or second drive current is passed through a coil of the solenoid to drive the movable piece of the solenoid from the first to the second state or from the second to the first state, respectively. A solenoid operating state detection device for detecting the operating state of a solenoid, comprising: an AC signal output means for passing an AC signal through the solenoid coil after the first or second drive current is passed through the solenoid coil; and a phase difference detection means for detecting a phase difference between the AC signal flowing through the AC signal and the AC signal output from the AC signal output means, and detecting the operating state of the solenoid based on the phase difference detected by the phase difference detection means. A solenoid operating state detection device characterized by: