JPH06333732A - Apparatus for detecting actuation of solenoid for control - Google Patents

Abstract

PURPOSE:To provide a circuit for detecting the actuation of a solenoid for control by electrical means. CONSTITUTION:A detector is provided for detecting the displacement of the moving core of a solenoid when a driving signal Vs is applied to the solenoid 2 for control. The detector comprises a comparator 7 that detects the changes in the counterelectromotive force across the solenoid with the displacement of the core. A signal generator 10 turns a relay 3 on and off by the on-off operation of a transistor so that the driving signal Vs may be applied as a series of pulses for a predetermined period of time. The detection of the displacement of the core is carried out a predetermined time after the application of the pulsating driving signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control solenoid operation for electrically detecting whether or not a control solenoid normally operates (whether or not a movable iron core is displaced) in a control system of various devices using solenoids. The present invention relates to a detection circuit.

[0002]

2. Description of the Related Art A coil is wound around a fixed iron core, and a movable iron core is operated by using a magnetic attraction force obtained by energizing the coil. The mechanical force obtained is generally a linear force, but some have been devised to obtain a rotational force.

The above-mentioned solenoids are classified into AC solenoids and DC solenoids according to the type of power source. Generally, DC solenoids with a constant magnetic flux, no iron loss, and no noise problems are often used, and are called plungers. The plunger type structure, in which the iron core moves linearly in the coil, is used for the most part. (Hereinafter, the movable iron piece is also referred to as a plunger.) FIG. 4 is a schematic view of a solenoid having the above various plunger structures. In the figure, (A) is the most common plunger type, (B) is the leakage flux type, (C)
Is a flat plate type, (D) is a clapper type, and (E) is a hinge type.

The solenoid is a control device having a simple structure that skillfully applies a magnetic action by electric current, and is widely used in industrial equipment, commercial equipment, and entertainment equipment.

By the way, when a device is controlled by a solenoid incorporated in the device (for example, a plunger type solenoid), mechanical operation of the solenoid (displacement of the plunger) is actually performed only by applying a solenoid drive current. It is usually impossible to judge from the appearance whether or not
Conventionally, as a means to determine whether the solenoid has operated reliably, a sensor for detecting the displacement of the plunger is provided adjacent to the solenoid, and the sensor switch is mechanically turned on by the displacement of the plunger, and its output The method of judging by a signal was generally adopted.

As another detection method, a method has been devised in which a change in the drive current of the solenoid caused by the displacement of the plunger is detected and taken out as an electric signal.

[0007]

However, each of the above methods has the following problems.

First, regarding the mechanical detection method, (1) a sensor is required, and a moving mechanism of the solenoid and a connecting mechanism for the sensor are required, so that the entire structure becomes complicated and the durability deteriorates.

(2) It is necessary to provide a line for transmitting the output of the sensor separately from the drive signal line for the solenoid.

Further, the method for detecting the change in the drive current of the solenoid is as follows: (1) When the actual general use condition of the solenoid is observed, the movable range of the plunger is wide and accurate detection can be made based on the change in the drive current. Hard to get.

(2) When the movement of the plunger in the solenoid is sluggish, the displacement determination is made before the displacement of the plunger is completely completed, which may result in erroneous detection.

The present invention has been made in view of the above circumstances, and provides a control solenoid actuation detection circuit for reliably electrically detecting the presence or absence of actuation of a control solenoid.

[0013]

SUMMARY OF THE INVENTION The present invention provides a control solenoid actuation detecting device for detecting whether or not a movable iron core in a solenoid is displaced when a drive signal is applied to the controlling solenoid. By providing a control solenoid operation detection device characterized by detecting a change in voltage appearing across the varistor through the drive signal path by the back electromotive force generated in the control solenoid with the transition, Further, the drive signal of the control solenoid is applied in a continuous pulse form for a predetermined time, and the presence or absence of the displacement of the movable iron core is detected at every predetermined time after the application of each pulse drive signal is started. The above object is achieved by providing a control solenoid actuation detecting device for controlling.

[0014]

[Function] When the control solenoid is energized (drive signal is applied), the plunger is displaced by the magnetic attraction of the magnetic field generated inside. At this time, the magnetic flux in the solenoid is changed, and the counter electromotive force is generated in the solenoid by electromagnetic induction. Occurs.

The varistor via the drive signal path generally serves as a switch protection element. However, when a reverse current flows through the drive signal path due to the counter electromotive force, the voltage appearing across the varistor is the above-mentioned. It corresponds to the change in magnetic flux due to the displacement of the plunger, and the voltage-current characteristic of the varistor gives a terminal voltage appropriate for detecting the back electromotive force when the back electromotive force is generated.

Therefore, it becomes possible to detect the displacement of the plunger by inputting the varistor voltage to the preset comparison voltage and the comparator.

On the other hand, it takes several tens of milliseconds to move the plunger, although it depends on the size of the movable area. Therefore, after the solenoid is energized, a strobe is set up during the transition of the plunger after a certain amount of time has passed, and the output of the comparator is taken into the control circuit as detection data.

Therefore, even if the varistor voltage is increased for a short time and the comparator erroneously outputs when the plunger does not move for some reason or when the plunger stops halfway, this is immediately detected. Since the data is not used, it is possible to reliably determine whether or not the plunger has moved normally.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control solenoid operation detecting device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of a control solenoid operation detecting device according to the present invention, and FIG. 2 is a diagram showing the voltage across a varistor, the output of a comparator and the data acquisition when a drive signal is applied to the control solenoid. The strobe pulse waveform is shown.

Further, FIG. 3 is a diagram showing a time variation of the voltage across the varistor and the output of the comparator when a drive signal is applied to the control solenoid in a state where the plunger is not inserted.

In FIG. 1, a power supply circuit 1 is a three-terminal type monolithic IC (eg, Fairchild 7800).
Series) 13 voltage regulator,
The drive signals Vs and Vcc (circuit power supply voltage) of the control solenoid 2 are supplied. In this embodiment, Vs = 24V,
Vcc = 12V.

One end of the coil of the control solenoid 2 is grounded, and the other end is applied with the drive signal Vs via the relay switch 3 and is connected to the varistor 4.

The terminal voltage Vx of the varistor 4 is determined by the comparator 7
The comparator 7 outputs the detection signal S1 at the Vcc level when Vx exceeds the reference voltage Vref which is appropriately set by the variable resistor VR in advance.

Since the relay switch 3 is turned on by energizing the electromagnet coil L while the NPN transistor Q1 is on, the transistor Q1 is turned on.
The pulsed drive signal Vs can be applied to the control solenoid 2 by controlling the base-emitter voltage of the.

The pulse generator 10 generates a clock pulse f1 of, for example, 500 Hz, delays the signal appropriately with a delay element 11 (for example, 12 ms), and then outputs N as a strobe pulse P.
It is inputted to the AND gate N1 together with the detection signal S1.

The NAND gate N1 inputs the data of the detection signal S1 when the strobe pulse P rises to the flip-flop circuit 12 as detection data, and the data is latched. That is, the output of the NAND gate N2 is fixed at "H", and thereafter, the transistor Q1 is constantly turned on regardless of the output of the NAND gate N1.

F2 of the pulse generator 10 is a drive signal pulse for continuously applying the drive signal in a pulse form for a predetermined time, and the drive signal application state (Q1 ON state) at the logic output "H", "H" → " At "L", Q1 is turned off, and a transition detection waiting state is entered. When the displacement of the plunger is not detected (when the output of the NAND gate N2 does not become "H"), the state becomes "L" → "H" and the drive signal is applied again, and the above is repeated for a predetermined time.

Next, as shown in FIG. 2, the terminal voltage Vx of the varistor 4 draws a transition curve which gradually approaches 0V during the transition of the plunger due to counter electromotive force generated at time t1 after the application of the drive signal Vs.

The reference voltage Vre is set so that the width of the detection signal S1 output from the comparator 7 becomes an appropriate value determined by the magnetic attraction force of the control solenoid 2 and the movable range of the plunger.
f is preset by the variable resistor VR. In this embodiment, 26
It is about ms.

Under the above conditions, the strobe pulse P
Is set by the delay element 11 so as to stand at the time when the delay time Td elapses from the time t1 when the drive signal is applied, so that the detection signal S1 is generated at the time when the voltage Vx across the varistor is surely generating the counter electromotive force by the plunger. Will be captured as detection data.

If the plunger does not change or if it slightly changes momentarily and then stops, the drive signal Vx changes only at the moment due to the counter electromotive force of the solenoid itself, as shown in FIG. The detection signal S1 is output at an instant, but even if the displacement of the plunger is not sufficient, the detection data with the displacement is output.

Therefore, in order to prevent the possibility of erroneous detection, the strobe pulse P is applied with a certain delay after the drive signal Vx is applied and the plunger starts to shift as described above.
It can be seen that is sure to be set and should not be detected immediately after the start of the transition.

The gist of the present invention resides in that the operation confirmation of the control solenoid is detected by detecting the change in the voltage across the varistor inserted in the drive signal path. The type of varistor used in the circuit of FIG. Of course, the configuration of the comparator, the configuration of the logic circuit, the circuit of the pulse generator, etc. are not limited to those shown in the present embodiment.

Further, if the present invention is applied, it is not difficult to say that the invention can be applied to the operation confirmation detection of a so-called solenoid valve (solenoid valve) having the same structure as the control solenoid.

[0036]

As described above, the control solenoid actuation detecting device according to the present invention detects the counter electromotive force generated in the solenoid due to the displacement of the movable iron piece in the solenoid as a change in the voltage appearing across the varistor, and also makes a mistake. Since it is configured to prevent detection, it has excellent effects as described below.

(1) It has an excellent effect that it can surely electrically detect whether or not the control solenoid is operated.

(2) It has an excellent effect that the detection circuit is contactless and contactless, and a dedicated detection line is unnecessary.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a control solenoid operation detection device according to the present invention.

FIG. 2 is a diagram showing a time change of a voltage across a varistor and a comparator output and a detection strobe position when a drive signal is applied to a control solenoid.

FIG. 3 is a diagram showing a time change of a voltage across a varistor and a comparator output when a drive signal is applied to a control solenoid in a state where a plunger is not inserted.

FIG. 4 is a structural schematic view showing a control solenoid and a movable iron piece having various structures.

[Explanation of symbols]

 1 Power Supply Circuit 2 Control Solenoid 3 Relay Switch 4 Varistor 7 Comparator 10 Pulse Generator 11 Delay Element 12 Flip Flop Circuit 13 Monolithic IC S1 Detection Signal Vs Drive Signal Vref Reference Voltage Vx Varistor Terminal Voltage Vs Drive Signal Vcc Circuit Power Supply Voltage VR variable resistance N1, N2 NAND gate f1 clock pulse f2 drive signal pulse L electromagnet coil Q1 NPN transistor P strobe pulse Td delay time

Claims (2)

[Claims] 1. A control solenoid actuation detection device for detecting whether or not a movable iron core in a solenoid is displaced when a drive signal is applied to the control solenoid. The control solenoid actuation detection device is characterized in that a change in voltage due to the counter electromotive force appearing at both ends of the varistor via the drive signal path is detected by the counter electromotive force. 2. A drive signal of a control solenoid provided with a pulse generator is applied in a continuous pulse form for a predetermined time, and the presence or absence of displacement of the movable iron core is detected every time a predetermined time elapses after the application of each pulse drive signal is started. The solenoid actuation detecting device for control according to claim 1, wherein: