JPH0648004U - Solenoid valve drive circuit - Google Patents

Abstract

(57) [Summary] [Purpose] Even when the control signal is turned off and the solenoid valve is closed (or open), it is possible to grasp the time when the solenoid valve is completely closed (or open). A valve drive circuit is provided. A solenoid valve actuator A, a first switching element Q ₁ connected in series to the solenoid valve actuator A, a second switching element Q ₂ connected in series to the first switching element Q ₁ , A resistor R ₂ connected in parallel to the first switching element Q ₁ is included, and when the first switching element Q ₁ and the second switching element Q ₂ are both turned on, the solenoid valve actuator A is opened. Or the closing operation is started, and the first
When the switching element Q ₁ is turned off, the closing or opening operation of the solenoid valve actuator A is started, and the second switching element Q ₂ is turned off after a lapse of a predetermined time from the end of the opening and closing operation of the solenoid valve. It will be. Here, a transistor or a MOS type FET is used as the switching element.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electromagnetic drive circuit. More specifically, the present invention relates to a solenoid valve drive circuit capable of detecting the time when the solenoid valve is completely opened or closed.

[0002]

[Prior art]

 In the automobile industry, research is being conducted on combustion conditions in engines in order to comply with emission standards for pollutants from exhaust gas and to improve combustion efficiency. As part of this research, a sampling valve installed in the combustion chamber (a type of solenoid valve, hereinafter simply referred to as the solenoid valve) is used to sample gas in the combustion chamber.

As a drive circuit for the actuator A of this solenoid valve, as shown in FIG. 6, conventionally, as shown in FIG. 6, an actuator A, a resistor R connected in series with the actuator A, and a transistor Q connected in series with this resistor are provided. A drive circuit including and is used. Then, in this drive circuit, when the control signal is turned on to the base B of the transistor Q, the solenoid valve is opened (or closed), and conversely, when the control signal is turned off, the solenoid valve is closed (or open). Become. Therefore, in principle, if the on / off of the control signal is monitored, the time when the solenoid valve is opened / closed can be known, and the time when the gas sampling is performed should be known.

However, since there is a time delay Δt in the opening / closing operation of the solenoid valve (see FIG. 7), the solenoid valve may not be completely opened if the on / off of the control signal is only monitored. I can't know when it was closed. However, this time delay does not pose a problem when the solenoid valve is opened and closed at a low speed.

However, in order to further reduce the pollutants in the exhaust gas and further improve the combustion efficiency, an attempt is made to grasp the combustion state at each crank rotation angle, the air-fuel ratio near the spark plug before ignition, and the residual gas concentration. Has been done. For this reason, the opening and closing of the solenoid valve has become possible at high speed. When the solenoid valve is opened and closed at high speed in this way, the time delay Δt, which is not a problem when the solenoid valve is opened and closed at low speed, is becoming a problem. For this reason, it has become necessary to know when to open / close the solenoid valve by a method different from the conventional method.

As a result of earnest studies on this point, the present inventor has found that when the control voltage shown in FIG. 7A is input to this drive circuit, the current flowing through the circuit is very small as shown in FIG. 7B. It was found to fluctuate. Then, in FIG. 7 (b), it was also found that the point where the electric current slightly fluctuates after the rising is the time when the solenoid valve is completely opened (or closed). The current changes in this way because the inductance of the solenoid of actuator A changes with the opening (or closing) of the solenoid valve, but when the solenoid valve is completely open (or closed), the change occurs. Is probably due to a sudden stop. Therefore, by monitoring this change, the time when the control signal is input and the solenoid valve is completely opened (or closed) can be grasped.

However, when the control signal is turned off and the solenoid valve is closed (or opened), no current flows in the circuit. Therefore, since the above-mentioned change does not appear, it is impossible to grasp the time when the electromagnetic valve is completely closed (or opened).

[0008]

[Problems to be solved by the device]

 The present invention has been made in view of the problems of the prior art, and even when the control signal is turned off and the solenoid valve is closed (or opened), the solenoid valve is completely closed (or opened). It is an object of the present invention to provide a solenoid valve drive circuit capable of grasping the time when

[0009]

[Means for Solving the Problems]

 A first aspect of a solenoid valve drive circuit of the present invention is a solenoid valve actuator, a first switching element connected in series with the solenoid valve actuator, and a second switching element connected in series with the first switching element. And a resistor connected in parallel with the first switching element, and by opening both the first switching element and the second switching element, the opening or closing operation of the solenoid valve actuator is performed. Is started and the closing or opening operation of the solenoid valve actuator is started by turning off the first switching element, and after the elapse of a predetermined time from the end of the opening / closing operation of the solenoid valve, the second switching element Is turned off.

A second aspect of the solenoid valve drive circuit of the present invention is a solenoid valve actuator, a switching element connected in series to the solenoid valve actuator, an AC power source and an impedance connected in parallel to the solenoid valve actuator. And an alternating current circuit having: and an alternating current superposed on the solenoid valve actuator by the alternating current circuit.

[0011]

[Action]

 Since the first aspect of the solenoid valve drive circuit of the present invention is configured as described above, even if the first switching element is turned off, the second switching element is turned on. A current flows through the resistor connected to. As described above, this current slightly changes when the solenoid valve is completely opened (or closed) and the operation of the solenoid valve actuator is suddenly stopped. Therefore, the time when the solenoid valve is completely opened (or closed) can be grasped by detecting the minute change in the current flowing through this resistance.

Since the second aspect of the solenoid valve drive circuit of the present invention is configured as described above, the impedance of the AC circuit connected in parallel to the solenoid valve actuator is changed according to the change in the inductance of the solenoid valve actuator. Also changes. Therefore, for example, by measuring the voltage change across the resistance of the AC circuit, the time when the solenoid valve is completely opened (or closed) can be grasped.

[0013]

EXAMPLES Hereinafter, the present invention will be described based on examples with reference to the accompanying drawings, but the present invention is not limited to these examples.

Embodiment 1 FIG. 1 is a circuit diagram of an embodiment of the first aspect of the present invention, in which a solenoid valve actuator A is connected in series with a resistor R ₁ , a first transistor Q ₁ and a second transistor Q _2. it is one in which further the first transistor Q ₁ to the resistor R2 which are connected in parallel.

Although a transistor is used as the switching element in the example shown in FIG. 1, the switching element is not limited to this, and a MOS type FET can also be preferably used.

The voltage V ₁ is applied to the circuit configured as described above, and the control signals shown in FIGS. 2A and 2B are input to the bases B of the first transistor Q ₁ and the second transistor, respectively. Then, the first transistor Q ₁ and the second transistor Q ₂ are turned on, and a current flows through the circuit. The first half of FIG. 2C is a graph schematically showing the change in current at that time. As is clear from the figure, a slight change in the current is observed just before the steady state is reached. The point at which this current slightly changes is the time when the solenoid valve is completely opened (or closed) as described above. The current value I ₁ in the steady state in this case is represented by I ₁ = V ₁ / R ₁ .

The control signal input to the base B of the first transistor Q ₁ is turned off after a lapse of a predetermined time after the current I ₁ flows in the steady state, but at this time, the second transistor Q ₂ is not yet turned on. Since it is on, current continues to flow through resistors R ₁ and R ₂ . The current value I _{2 at} that time is represented by I ₂ = V ₁ / (R ₁ + R ₂ ). The latter half of FIG. 2 (c) is a graph schematically showing the change in current at that time. As is clear from the figure, a portion in which the current slightly changes is recognized in the latter half as in the first half. For this reason, the solenoid valve is completely closed (or opened) for the same reason as described above.

In FIG. 3, a MOS type FET 2SK591 is used for the first switching element Q ₁ , a MOS type FET 2SK591 is used for the second switching element Q ₂ , and a resistor R _{1 is set} to 0. 22 is a graph when the voltage change across the solenoid valve (solenoid) is measured by configuring a circuit similar to that shown in FIG. 1 with 22Ω and a resistance R ₂ of 2.2Ω. As indicated by the arrows in the figure, a slight change in voltage is observed in each of the first half and the second half. Therefore, it can be seen that from this minute change in voltage, there is also a minute change in current corresponding to this minute change in voltage.

As described above, according to the first embodiment, the time when the solenoid valve is completely opened or closed can be known from the minute change in the current flowing in the circuit or the minute change in the voltage.

Embodiment 2 FIG. 4 is a circuit diagram of an embodiment of the second aspect of the present invention, in which a transistor Q ₃ is connected in series to a solenoid valve actuator A, and an AC power source E and a resistance are connected to the solenoid valve actuator A. A circuit having R ₃ and a capacitor C is connected in parallel.

Although a transistor is used as a switching element in the example shown in FIG. 4, a MOS type FET can also be suitably used as in the first embodiment.

[0022] In this circuit, when the control signal is input base B of the transistor Q _3, transistor Q ₃ is turned on, the solenoid valve is opened (or closed). As described above, since the inductance of the solenoid valve actuator A changes during the opening / closing operation of the solenoid valve, the inductance of the solenoid valve actuator A and the resistance R _{3 of the} circuit connected in parallel to this solenoid valve actuator A The value of the impedance consisting of the capacitor C changes accordingly. Therefore, the current I ₃ flowing in the circuit also changes. Therefore, the voltage across the resistor R ₃ changes during the opening / closing operation of the solenoid valve. On the contrary, when the opening / closing operation of the solenoid valve ends, the change in the inductance of the solenoid valve actuator A also ends. Therefore, the voltage change across the resistor R ₃ is also terminated.

Therefore, by measuring the voltage change across the resistor R ₃ , it is possible to know the time when the solenoid valve is completely opened or closed. FIG. 5B is a graph schematically showing the voltage change across the resistor R ₃ when the control signal shown in FIG. 5A is input to the transistor Q ₃ . As described above, the voltage changes during the opening / closing operation of the solenoid valve, and the voltage change ends when the solenoid valve is completely opened or closed.

As described above, also in the second embodiment, it is possible to grasp the time when the solenoid valve is completely opened or closed, as in the first embodiment.

[0025]

[Effect of device]

 As described above, according to the present invention, it is possible to accurately grasp the opening / closing time of the solenoid valve. Therefore, by opening and closing the gas sampling solenoid valve according to the present invention, it is possible to accurately grasp the time of gas sampling.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the first aspect of the present invention.

FIG. 2 is a graph schematically showing a change in current in the example, where (a) shows a waveform of a control signal input to a first transistor and (b) shows a waveform of a control signal input to a second transistor. The waveform of the control signal that is generated is shown in FIG.

FIG. 3 is a graph showing a voltage change across a solenoid valve (solenoid) when the circuit according to the first aspect of the present invention is specifically configured.

FIG. 4 is a circuit diagram of an embodiment of the second aspect of the present invention.

5A and 5B are graphs showing changes in voltage across the resistance of the AC circuit in the example, where FIG. 5A shows the waveform of the control signal input to the transistor, and FIG. 5B shows the voltage waveform across the resistance. Indicates.

FIG. 6 is a drive circuit diagram of a conventional solenoid valve actuator.

7A and 7B are graphs schematically showing changes in current in the example, where FIG. 7A shows a waveform of a control signal input to a transistor and FIG. 7B shows a current waveform.

[Explanation of symbols]

A Solenoid valve actuator Q, Q ₁ , Q ₂ , Q ₃ transistor or F
Switching element such as ET B Base R, R ₁ , R ₂ , R ₃ , R _a , R _b Resistance C Capacitor I ₁ , I ₂ , I ₃ Current E AC power supply

Claims (2)

[Scope of utility model registration request] 1. A solenoid valve actuator, a first switching element connected in series to the solenoid valve actuator, a second switching element connected in series to the first switching element, and a parallel connection to the first switching element. And a resistor connected to the first switching element and the second switching element are both turned on to start an opening or closing operation of the solenoid valve actuator, and the first switching element is turned off. As a result, a closing or opening operation of the solenoid valve actuator is started, and the second switching element is turned off after a predetermined time has elapsed after the opening / closing operation of the solenoid valve is completed. . 2. An electromagnetic valve actuator, a switching element connected in series to the electromagnetic valve actuator, and an alternating current circuit having an alternating current power source and an impedance connected in parallel to the electromagnetic valve actuator. An electromagnetic valve drive circuit, wherein alternating current is superimposed on the electromagnetic valve actuator by an alternating current circuit.