JPH1167536A - Plunger position detector for electromagnetic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger position detector, which can detect the position of the plunger of an electromagnetic device with such a simple constituted that requires no fine adjustment. SOLUTION: A resonance circuit 1 contains a coil 3 for operating the plunger of an electromagnetic device. The resonance circuit 1 is oscillated 2 by intermittently conducting the resonance circuit 1 by means of a switching element Q1 , and the element Q1 is turned on/off through a pulse signal from a pulse- generating circuit 4. The coil 3 is switchingly connected to a drive circuit 10 of the electromagnetic device or the resonance circuit 1 by means of switching elements 51 and 52 . The inductance of the coil 3 varies depending upon the position of the plunger of the electromagnetic device is a sucked position or a retreated position. Therefore, the position of the plunger can be detected from the voltage Vr generated across the both ends of a detecting resistor Rs by a resonance current I1 , because the resonating conditions of the resonance circuit 1 also vary depending on the position of the plunger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger position detecting device for detecting a plunger position of an electromagnetic device such as a latch solenoid or an electromagnetic valve.

[0002]

2. Description of the Related Art Conventionally, various configurations for detecting the position of a plunger of an electromagnetic device such as a latch solenoid or an electromagnetic valve have been proposed (JP-A-3-214710, JP-A-4-196203 and JP-A-5-211105). No.). One example is a position detection sensor 30 using a reed switch 31 as shown in FIG. When this position detection sensor 30 is attached to an electromagnetic device (solenoid) 20 as shown in FIG. 19, the reed switch 31 is turned on / off by the leakage magnetic flux because the leakage magnetic flux of the electromagnetic device 20 varies depending on the position of the plunger 21. To detect the position of the plunger.
In addition, the detected position is the lighting of the light emitting diode LED.
The display is turned off.

[0003]

In the above conventional example, it is necessary to attach the position detecting sensor 30 to the electromagnetic device 20, and when the reed switch 31 is used, the position detecting sensor 30 with respect to the electromagnetic device 20 depends on the characteristic variation. There is a problem that accurate detection cannot be performed unless the mounting position is finely adjusted, and the adjustment is extremely difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plunger position detecting device of an electromagnetic device capable of detecting the position of a plunger with a simple structure without requiring fine adjustment. is there.

[0005]

According to a first aspect of the present invention, there is provided a plunger position detecting device for detecting a position of a plunger of an electromagnetic device for switching an operating direction of a plunger in accordance with a direction of energizing a coil. The apparatus has a resonance circuit including a coil, and detects the position of the plunger based on the resonance condition of the resonance circuit that changes according to the position of the plunger. The position of the plunger can be detected with a simple configuration without requiring adjustment.

According to a second aspect of the present invention, in the first aspect, the resonance circuit includes a capacitor and a resistor. According to a third aspect of the present invention, in the first aspect of the present invention, a switching element for interrupting energization of the resonance circuit and a pulse generating circuit for outputting a pulse signal for turning on and off the switching element are provided. Thus, a resonance current can flow through the resonance circuit with a simple configuration.

According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided switching means for switching and connecting the coil between a drive circuit for energizing the coil and driving the electromagnetic device and a resonance circuit. By disengaging the resonance circuit from the coil during the operation of the plunger and connecting the resonance circuit to the coil only when detecting the position of the plunger, the position can be detected without affecting the operation of the plunger.

According to a fifth aspect of the present invention, in the first aspect, the voltage conversion circuit converts a resonance current of the resonance circuit, which changes according to the position of the plunger, into a voltage signal, and the output signal from the voltage conversion circuit. And a state determination circuit that determines a suction or return state of the plunger and outputs a state signal indicating each state, whereby the position of the plunger can be stably detected.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the voltage conversion circuit includes a parallel connection of the first resistor and the capacitor between the power supply and the switching element which is turned on by a voltage drop of the detection resistor through which the resonance current flows. A circuit and a second resistor are connected in series, and a voltage signal is outputted from a connection point between the parallel circuit and the second resistor, and a substantially constant voltage signal corresponding to a position of the plunger is obtained. Thus, the position of the plunger can be detected efficiently and with a simple circuit configuration.

[0010] According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the state determination circuit converts the output signal from the voltage conversion circuit into a threshold value having hysteresis characteristics set in accordance with the attraction or return state of the plunger. And an output circuit having a switching element that is turned on and off by the output of the comparator, so that the comparator has a hysteresis characteristic even if the output signal from the voltage conversion circuit is slightly distorted. Since the position of the plunger is determined by comparing the plunger position with the threshold value, the plunger position can be accurately detected,
Noise resistance can also be improved. Further, by providing an output circuit, it can be easily connected to other circuits and devices.

According to an eighth aspect of the present invention, in the fifth aspect of the present invention, the state determination circuit converts the output signal from the voltage conversion circuit to a threshold value having a hysteresis characteristic set in accordance with the attraction or return state of the plunger. First and second to compare with
Characterized in that the suction, return or abnormal state of the plunger is determined according to the combination of the outputs of the first and second comparators. An abnormal state can also be detected.

A ninth aspect of the present invention is characterized in that, in the eighth aspect of the present invention, there is provided means for varying each threshold value in the first and second comparators, and the variable threshold value is adjusted. It is possible to set an appropriate threshold value according to the use of the electromagnetic device, and it is possible to easily cope with various uses.

[0013]

(Embodiment 1) FIG. 1 is a circuit block diagram showing Embodiment 1 of the present invention. This embodiment includes an oscillation circuit 2 for electromagnetic devices such as a latch solenoid or solenoid valves resonant circuit 1 including a coil 3 for the plunger operation comprising comprises a switching element Q ₁ intermittently energizing the resonant circuit 1, Switching the coil 3 between a pulse generation circuit 4 for outputting a pulse signal for turning on and off the switching element Q ₁ , a drive circuit 10 for energizing the coil 3 to drive the electromagnetic device and the resonance circuit 1, Switching element 5 ₁ , 5 ₂ for changing the resonance circuit 1 that changes according to the position of the plunger 21.
It is detected as a voltage by the resonance current I ₁ detected resistor Rs.

Switching elements 5 ₁ and 5 ₂ such as AC relays are connected to both ends of the coil 3, a resistor R ₁ is connected in series, and a capacitor C ₁ is connected in parallel to form the resonance circuit 1. is there. One power V _cc to a connection point of the switching element 5 ₁ and the capacitor C ₁ is connected, the switching element Q and the other connection point of the switching element 5 ₂ and the capacitor C ₁ consisting of FET via the resistor R ₂ Drain D of ₁
Is connected.

Meanwhile, with connecting to ground the source S of the switching element Q ₁ through the detection resistor Rs, the resistance R ₃ for bias between the gate G- source S is connected. The switching element Q ₁ is has a parasitic diode D ₁ which is inserted between the drain D- source S. The switching elements 5 ₁ and 5 ₂ are each connected to a common terminal at one end of the coil 3, and switch the contact from the drive circuit 10 to the resonance circuit 1 only while receiving a detection start signal given from the outside.

The pulse generating circuit 4, there is to generate a square pulse having a predetermined period only while receiving the detection start signal, the switching element by applying the pulse signal to the gate G of the switching element Q ₁ the Q ₁ at a predetermined frequency is turned on and off. The drive circuit 10 switches the direction of energization to the coil 3 in accordance with an externally applied suction signal and a return signal, and switches the operating direction of the plunger 21 by exciting the coils 3 in different directions.

Next, the operation of this embodiment will be described.
First, a detection start signal is input from a control device (not shown) for controlling the electromagnetic device when the electromagnetic device is not operating.
The switching elements 5 ₁ and 5 ₂ operate according to the detection start signal, and the coil 3 is disconnected from the drive circuit 10 and connected to the resonance circuit 1 by switching the contact from the drive circuit 10 to the resonance circuit 1. Further, since the pulse generating circuit 4 which receives the detection start signal to start the output of the pulse signal, the switching element Q ₁ and the pulse signal is input to the gate G of the switching element Q ₁ as shown in FIG. 2 or FIG. 3 Turns on / off at a predetermined cycle. Thus, since the energization from the power supply V _cc to the resonant circuit 1 is interrupted, the resonant circuit first oscillation circuit 2 oscillates flows resonance current I _1.

Here, since the inductance of the coil 3 differs depending on whether the plunger of the electromagnetic device is in the attraction position or the return position, the resonance condition of the resonance circuit 1 also changes depending on the position of the plunger, and the resonance current is changed. I ₁ also varies depending on the position of the plunger. At this time, the waveform of the voltage (output voltage) Vr generated across the detection resistor Rs due to the resonance current I ₁ also changes according to the position of the plunger as shown in FIGS. 2 and 3. The position can be detected.

As described above, according to the present embodiment, the resonance circuit 1 including the coil 3 of the electromagnetic device is formed, and the resonance circuit 1 is used by utilizing the fact that the inductance of the coil 3 changes according to the position of the plunger. it is possible to detect the position of the plunger from the resonance current I ₁ flowing through. Therefore, unlike the related art, it is not necessary to attach the position detection sensor 30 to the electromagnetic device, and it is not necessary to finely adjust the characteristic variation of the position detection sensor 30, and the position of the plunger can be easily detected. Further, since there is no need to directly attach the electromagnetic device, there is no fear of failure due to vibration or the like during operation of the electromagnetic device. Further, it can be realized with a simple circuit configuration including only the resonance circuit 1 and its peripheral circuits without requiring a complicated circuit.

(Embodiment 2) FIG. 4 shows Embodiment 2 of the present invention.
FIG. 4 is a circuit block diagram showing As shown in FIG. 4, the basic configuration of the present embodiment is the same as that of the first embodiment. Therefore, the common components are denoted by the same reference numerals, and description thereof will be omitted. Only the features that are the features of the present embodiment will be described. I do. In the present embodiment, a voltage conversion circuit 6 that converts a resonance current flowing through the detection resistor Rs to a substantially constant voltage, and a suction or return state of the plunger is determined based on an output voltage V _O from the voltage conversion circuit 6, and each state is determined. State determination circuit 7 that outputs a state signal Vm indicating
There is a feature in having a.

FIG. 5 is a circuit diagram showing a specific example of the voltage conversion circuit 6. Voltage conversion circuit in this embodiment, as shown in FIG. 5. 6, base - via the transistor Q ₂ to which the detection resistor Rs is connected between the emitter, the resistor R ₅ between the collector and the power supply V _DD of the transistor Q ₂ And a parallel circuit of a capacitor C ₂ and a resistor R ₆ connected to each other, and an output voltage V _O is taken out from a connection point between the parallel circuit and the resistor R ₅ .

As shown in FIGS. 6 and 7, a pulse signal is output from the pulse generation circuit 4 and the switching element Q ₁ is output.
There when turned on and off, to turn on the transistor Q ₂ is the voltage Vr at the time exceeding a predetermined level Va generated across the sense resistor Rs by the resonant current I _1. When transistor Q ₂ is turned on, decreases the output voltage V _O, as shown in FIG. 8, the output voltage V _O and the transistor Q ₂ is turned off is increased.

[0023] Here, when the resistance value of the resistor R ₅ is set smaller than the resistance value of the resistor _{R 6 (R 5 <R 6} ), the output voltage V _O when the transistor Q ₂ is turned on to decrease the output voltage V _O of the speed when the transistor Q ₂ is turned off
Can be faster than the speed at which it rises. As a result, when the on-off switching element Q ₁ is repeated at a high speed, the output voltage V _O, as shown in FIG. 8 is repeatedly rise and fall within a predetermined range, its value can be regarded as substantially constant .

On the other hand, the waveform of the voltage Vr across the detection resistor Rs
Depends on the position of the plunger.
More resonance current I₁So that
Set the frequency of the pulse signal from the pulse generation circuit 4
Otherwise, as shown in FIGS. 6 and 7, the transistor Q_Twoof
The on-period is in the return state compared to the suction state
Becomes longer. That is, the plunger suction state and the return state
State and transistor Q _TwoHave different on-duty ratios
Output voltage V in the suction state_O(= V_Two) And return state
Output voltage V_O(= V₁) Is also different (V₁
<V_Two).

FIG. 9 is a circuit diagram showing a specific example of the state determination circuit 7. As shown in FIG. 9, the state determination circuit 7 in the present embodiment compares the output voltage V _O from the voltage conversion circuit 6 with a threshold Vref having hysteresis characteristics set corresponding to the attraction or return state of the plunger. And an output circuit 7b having a switching element (transistor Q ₃ ) that is turned on and off by the output of the comparator 7a.

The output voltage V _O is input to the inverting input terminal of the comparator 7a, and the threshold (voltage) V obtained by dividing the power supply voltage V _DD by the voltage dividing resistors R ₇ and R ₈ to the non-inverting input terminal.
ref is input. Between the output terminal and the non-inverting input of the comparator 7a it is resistor R ₉ in order to have the hysteresis characteristics are connected. The output circuit 7b includes resistors R ₁₀ and R ₁₁ connected between the power supply V _DD and the output terminal of the comparator 7a.
Of a series circuit, is composed of a resistor R _10, R transistor Q ₃ to the power supply V _DD resistor R ₁₂ to the connected and the collector to the emitter is connected with the base is connected to the connection point _11, the transistor Q ₃ It has from the connection point of the collector and the resistor R ₁₂ to the state signal Vm of H level and L level taken.

Here, the hysteresis characteristic of the threshold value Vref will be briefly described. First, the output voltage V _O of the voltage conversion circuit 6 is higher than the threshold value Vref (Vref <V _O ).
Since the output of the comparator 7a is L level when a circuit for creating a threshold Vref is configured to resistor R ₉ is connected in parallel with the dividing resistor R ₈ as shown in FIG. 10. The threshold value Vref _{1 at} this time can be expressed by the following equation.

[0028]

(Equation 1)

On the other hand, when the output voltage V _O of the voltage conversion circuit 6 is lower than the threshold value Vref (Vref> V _O ), the output of the comparator 7a goes to the H level.
The circuit for generating ref has a configuration in which a series circuit of resistors R _{9 to} R ₁₁ is connected in parallel to a connection point of the voltage dividing resistors R ₇ and R ₈ as shown in FIG. The threshold value Vref _{2 at} this time can be expressed by the following equation.

[0030]

(Equation 2)

As is apparent from the above two equations, two threshold values Vref ₁ and Vref ₂ (Vref ₁ <Vref ₂ ) are obtained. Therefore, as shown in FIG.
_{When O} falls below the threshold value Vref ₁ , the comparator 7
a output rose to Vref ₂ threshold becomes H level, the output of the output voltage V _O is been rising threshold exceeds Vref ₂ comparator 7a is the threshold at the L level It will be reduced to Vref _1.

That is, the output voltage V _O of the voltage conversion circuit 6
Is substantially constant but has some distortion. As described above, by giving the threshold value of the comparator 7a a hysteresis characteristic, the influence of the distortion of the output voltage V _O can be reduced, and the noise resistance can be reduced. It can also be improved. Next, the operation of this embodiment will be described with reference to the time chart of FIG. Inoperative are detected start signal H level from unillustrated controller or the like is input at the time, switched by the position detection line of the plunger to during which the switching element 5 _1, 5 ₂ contacts resonant circuit 1 side of the electromagnetic device Will be Here, if the plunger is initially in the return state, the output voltage V _O of the voltage conversion circuit 6 becomes V ₁ , so that the state determination circuit 7 outputs an L-level state signal Vm indicating the return state. . When the detection start signal from the control device in this state becomes the L level, the contacts of the switching element 5 _1, 5 ₂ is switched to the drive circuit 10 side, the pulse signal output from the pulse generating circuit 4 is stopped. When a suction signal is output from the control device to the drive circuit 10,
The drive circuit 10 excites the coil 3 to attract the plunger. Since the detection start signal is not output during this plunger operation period (L level), the position of the plunger is not detected.

[0033] When the detection start signal again from the suction completion to the control unit is outputted, the switching elements 5 _1, 5 ₂ operates, the coil 3 by the contact is switched from the driving circuit 10 side to the resonant circuit 1 side Are connected to the resonance circuit 1. Further, the pulse generation circuit 4 which has received the detection start signal starts outputting the pulse signal. Here, since the operation state of the plunger has changed from the return state to the suction state, the inductance of the coil 3 changes and the output voltage V _O of the voltage conversion circuit 6 changes from V ₁ to V _1.
2 and exceeds the threshold value Vref ₂ set between the voltages V ₁ and V ₂ . As a result, the state determination circuit 7 outputs an H-level state signal Vm indicating the suction state. When the detection start signal from the control device in this state becomes the L level, the contacts of the switching element 5 _1, 5 ₂ is switched to the drive circuit 10 side, the pulse signal output from the pulse generating circuit 4 is stopped. When a return signal is output from the control device to the drive circuit 10, the drive circuit 10 excites the coil 3 and returns the plunger. After the completion of the return, the detection start signal from the control device becomes H level, and the position of the plunger is detected in the same manner as described above.

The state signal Vm output from the state determination circuit 7 is applied to another circuit, for example, a circuit for turning on and off a light emitting element such as an LED, and the position of the plunger is visually determined by turning on and off the light emitting element. Can also be displayed. (Embodiment 3) FIG. 14 is a circuit diagram showing a state determination circuit according to Embodiment 3 of the present invention. Note that the basic configuration of the present embodiment is the same as that of the second embodiment. Therefore, the common portions are denoted by the same reference numerals, and illustration and description thereof are omitted. Only the features that are the features of the present embodiment will be described.

The present embodiment has two configurations exactly the same as the configuration of the state determination circuit 7 in the second embodiment. The voltage conversion circuit 6 is connected to the inverting input terminals of the first and second comparators 8a ₁ and 8a ₂ . the inputs the output voltage V _O, a state signal Vm ₁ from the first output circuit 8b ₁ connected to the first output terminal of the comparator 8a _1, which is connected to the second output terminal of the comparator 8a ₂ not only the suction state and the reset state of the plunger in conjunction with the state signal Vm ₂ from second output circuit 8b _2, is characterized in that the possible detection of the one nor abnormal state. Note that different thresholds Vref (1) and Vref (2) are set for the first and second comparators 8a ₁ and 8a ₂ (where Vref is the same).
(1)> Vref (2)). Also, which threshold value Vref (1), Vr
ef (2) also has a hysteresis characteristic.

Next, the present embodiment will be described with reference to the waveform diagram of FIG.
Will be described. The plunger now returns from the suction state
If it operates in the state, the output voltage V
_OIs V_TwoTo V₁To decline. Here, the first and second
Comparator 8a₁, 8a_TwoThreshold value Vref₁(1), Vr
ef_Two(1), Vref₁(2), Vref_Two(2) Both are V₁And V _Two
It is set between. Therefore, in the suction state, the first and
Second output circuit 8b₁, 8b_TwoH level from any of
State signal Vm₁, Vm_TwoIs output, but the plunger
If it returns, the output voltage V_ODecreases to the threshold V
ref₁If the value is lower than (1), the first output circuit 8a₁Status signal from
No. Vm₁Changes to the L level, and the output voltage V_OIs low
Lower threshold Vref₁If the value falls below (2), the second output circuit 8
a_TwoState signal Vm from_TwoChanges to the L level.

On the other hand, if the plunger operates from the return state to the suction state, the output voltage V _O of the voltage conversion circuit 6 rises from V ₁ to V ₂ , the output voltage V _O rises and the threshold voltage Vref ₂ If (2) is exceeded, the state signal Vm ₂ from the _second output circuit 8a ₂ changes to H level, and the output voltage V _O
Rises above the threshold value Vref ₂ (1), the state signal Vm ₁ from the _first output circuit 8a ₁ changes to the H level.

That is, two state signals Vm ₁ and Vm ₂
When both are at the H level, the plunger is in the suction state, when both are at the L level, the plunger is in the return state, and one of them remains at the H or L level, and the two state signals Vm ₁ , Vm ₂ If they are different, it can be determined that an abnormal state that is neither the return state nor the suction state has occurred. (Embodiment 4) FIG. 16 is a circuit diagram showing a state determination circuit according to Embodiment 4 of the present invention. Since the basic configuration of the present embodiment is the same as that of the third embodiment, the same reference numerals are given to the common portions, and illustration and description thereof are omitted. Only the features that are the features of the present embodiment will be described.

In this embodiment, the threshold values Vref (1) and Vref (2) in the first and second comparators 8a ₁ and 8a ₂ are used.
Partial pressure for setting the resistor R _13, instead variable resistance of R ₁₉ V
By using R ₁ and VR ₂ , the threshold values Vref (1),
The feature is that Vref (2) can be changed. That is, an electromagnetic device such as a general solenoid is often operating distance of the plunger depends on the application, according to this embodiment, the variable resistor VR _1, as shown in FIG. 17, V
First and second comparators 8a by changing the resistance value of R _{2 1,} the 8a ₂ threshold _{Vref 1 (1), Vref 2} (1),
Since Vref ₁ (2) and Vref ₂ (2) can be set freely, an appropriate threshold value can be set according to the operating distance, and it can be easily adapted to various uses. .

[0040]

According to the first aspect of the present invention, there is provided a plunger position detecting device for detecting a position of a plunger of an electromagnetic device for switching an operating direction of a plunger in accordance with a direction of energizing a coil, the device comprising a resonance circuit including a coil. Since the position of the plunger is detected based on the resonance condition of the resonance circuit that changes according to the position of the plunger, the position of the plunger can be detected with a simple configuration without the need for fine adjustment by the resonance circuit including the coil of the electromagnetic device. There is an effect that can be.

According to a third aspect of the present invention, there is provided a switching element for interrupting energization of the resonance circuit, and an on / off switch for the switching element.
Since a pulse generation circuit for outputting a pulse signal for turning off is provided, there is an effect that a resonance current can flow through the resonance circuit with a simple configuration. The invention according to claim 4 is provided with switching means for switching and connecting the coil between a drive circuit that drives the electromagnetic device by energizing the coil and the resonance circuit, so that the resonance circuit is disconnected from the coil when the plunger operates. By connecting the resonance circuit to the coil only when detecting the position of the plunger, there is an effect that the position can be detected without affecting the operation of the plunger.

According to a fifth aspect of the present invention, there is provided a voltage conversion circuit for converting a resonance current of a resonance circuit, which varies according to a position of a plunger, into a voltage signal, and a state in which the plunger is attracted or returned based on an output signal from the voltage conversion circuit. And a state determination circuit for outputting a state signal indicating each state, so that the position of the plunger can be stably detected.

According to a sixth aspect of the present invention, in the voltage conversion circuit, a parallel circuit of a first resistor and a capacitor and a second resistor are provided between a power supply and a switching element which is turned on by a voltage drop of a detection resistor through which a resonance current flows. Since they are connected in series and output a voltage signal from the connection point between the parallel circuit and the second resistor,
An approximately constant voltage signal corresponding to the position of the plunger can be obtained, and the position of the plunger can be detected efficiently and with a simple circuit configuration.

According to a seventh aspect of the present invention, there is provided a comparator wherein the state determination circuit compares the output signal from the voltage conversion circuit with a threshold having hysteresis characteristics set in accordance with the attraction or return state of the plunger. And an output circuit having a switching element that is turned on and off by the output of the plunger. Therefore, even if the output signal from the voltage conversion circuit is somewhat distorted, the plunger is compared with a threshold having hysteresis characteristics in the comparator. Since the position is determined, the position of the plunger can be accurately detected, the noise resistance can be improved, and the output circuit can be easily connected to other circuits and devices. is there.

According to an eighth aspect of the present invention, the state determination circuit compares the output signal from the voltage conversion circuit with threshold values having hysteresis characteristics set in accordance with the attraction or return state of the plunger. 2 is provided, and the suction, return, or abnormal state of the plunger is determined according to the combination of the outputs of the first and second comparators. There is an effect that it can be detected.

According to the ninth aspect of the present invention, since means for varying each threshold value in the first and second comparators are provided, the threshold value can be varied and adjusted. An appropriate threshold value can be set accordingly, and there is an effect that various applications can be easily handled.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a first embodiment.

FIG. 2 is a voltage waveform diagram of each part when the plunger is sucked in the above.

FIG. 3 is a voltage waveform diagram of each part when the plunger returns from the above.

FIG. 4 is a circuit block diagram showing a second embodiment.

FIG. 5 is a circuit diagram of a voltage conversion circuit in Embodiment 1;

FIG. 6 is a voltage waveform diagram of each part when the plunger is sucked in the above.

FIG. 7 is a voltage waveform diagram of each part when the plunger returns from the above.

FIG. 8 is a waveform chart for explaining an operation of the voltage conversion circuit in the above.

FIG. 9 is a circuit diagram of a state determination circuit in Embodiment 1;

FIG. 10 is a diagram for explaining a hysteresis characteristic of a threshold in the above.

FIG. 11 is a diagram illustrating a hysteresis characteristic of a threshold in the above.

FIG. 12 is a diagram for explaining the operation of the state determination circuit in the above.

FIG. 13 is a time chart for explaining the above operation.

FIG. 14 is a circuit diagram of a state determination circuit according to a third embodiment.

FIG. 15 is a diagram for explaining the operation of the state determination circuit in the above.

FIG. 16 is a circuit diagram of a state determination circuit according to a fourth embodiment.

FIG. 17 is a diagram for explaining the operation of the state determination circuit in the above.

FIG. 18 is a circuit diagram showing a conventional position detection sensor.

FIG. 19 is an external perspective view showing a state where the above is attached to an electromagnetic device.

[Explanation of symbols]

1 the resonant circuit second oscillation circuit 3 coil 4 pulse generating circuit 5 _1, 5 ₂ switching element Rs detection resistor

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[Procedure amendment]

[Submission date] January 5, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

Switching elements 5 ₁ and 5 ₂ such as AC relays are connected to both ends of the coil 3, a resistor R ₁ is connected in series, and a capacitor C ₁ is connected in parallel to form the resonance circuit 1. is there. One power V _cc to a connection point of the switching element 5 ₁ and the capacitor C ₁ is connected, the connection point between the resistor R ₁ and capacitor C ₁ connected in series to the other switching element 5 ₂ a resistor R ₂ the drain D of the switching element Q ₁ consisting of FET via the is connected.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

On the other hand, since the waveform of the voltage Vr at both ends of the detection resistor Rs varies depending on the position of the plunger, when for example the plunger suction, the transistor Q by the resonant current I _1
2 by setting the frequency of the pulse signal from the path <br/> pulse generating circuit 4 so that the time which is turned on is shorter than at the time of return, the transistor Q ₂ as shown in FIGS. 6 and 7 The ON period is longer in the return state than in the suction state. That is, in order to in the suction state of the plunger and the return state on-duty ratio of the transistor Q ₂ are different, the output voltage V _O of the output voltage V _O (= V ₂₎ and a return state in the suction state (= V ₁₎ (V ₁ <
V ₂ ).

Claims (9)

[Claims] 1. A plunger position detecting device for detecting a position of a plunger of an electromagnetic device for switching an operation direction of a plunger in accordance with a direction of energizing a coil, the plunger position detecting device having a resonance circuit including a coil, and changing according to the position of the plunger. A plunger position detecting device for an electromagnetic device, wherein the position of the plunger is detected based on a resonance condition of a resonance circuit. 2. The plunger position detecting device according to claim 1, wherein the resonance circuit includes a capacitor and a resistor. 3. The electromagnetic device according to claim 1, further comprising: a switching element for interrupting energization of the resonance circuit; and a pulse generating circuit for outputting a pulse signal for turning on and off the switching element. Plunger position detecting device. 4. The plunger position of an electromagnetic device according to claim 1, further comprising switching means for switching and connecting the coil between a drive circuit for driving the electromagnetic device by energizing the coil and a resonance circuit. Detection device. 5. A voltage conversion circuit for converting a resonance current of a resonance circuit that changes according to a position of a plunger into a voltage signal,
2. A plunger position of an electromagnetic device according to claim 1, further comprising: a state judging circuit for judging an attraction or return state of the plunger based on an output signal from the voltage conversion circuit and outputting a state signal indicating each state. Detection device. 6. A voltage conversion circuit comprising: a parallel circuit of a first resistor and a capacitor between a switching element that is turned on by a voltage drop of a detection resistor through which a resonance current flows and a power supply;
6. A plunger position detecting device for an electromagnetic device according to claim 5, wherein said resistors are connected in series, and a voltage signal is output from a connection point between said parallel circuit and said second resistor. 7. A comparator for comparing an output signal from the voltage conversion circuit with a threshold having hysteresis characteristics set in accordance with the attraction or return state of the plunger. The plunger position detecting device for an electromagnetic device according to claim 5, further comprising: an output circuit having a switching element that is turned off. 8. The state determination circuit includes first and second comparators for comparing an output signal from the voltage conversion circuit with a threshold having hysteresis characteristics set in accordance with the attraction or return state of the plunger. 6. The plunger position detecting device for an electromagnetic device according to claim 5, wherein the plunger suction, return, or abnormal state is determined according to a combination of the outputs of the first and second comparators. 9. The plunger position detecting device for an electromagnetic device according to claim 8, further comprising means for varying each threshold value in the first and second comparators.