JPS61277842A - Solenoid valve control circuit - Google Patents

Abstract

PURPOSE:To perform warming operation approximately matching with the temperature conditions by employing the variation of resistance due to self heating through power supply having the temperature of internal-combustion engine detected through positive characteristic thermister as the initial level for power supply control of solenoid valve. CONSTITUTION:Solenoid valve control circuit is comprising a positive characteristic thermister PH and a solenoid L of solenoid valve 1 to be controlled by the current through said thermister PH. Transistor Q and the solenoid L are inserted in series where switching operation of transistor Q will cause motion of movable core thus to open/close the solenoid valve 1. Diode D is the flywheel diode for absorbing the counter electromotive force of the solenoid L. Consequently, warming operation approximately matching with the temperature conditions can be achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to driving an internal combustion engine for an automobile in cold weather.
This relates to a control circuit for a solenoid valve used to control machine operation.

[Prior art] As a conventional control circuit technology for this type of solenoid valve,
1=53313 can be mentioned.

The above technology includes a temperature-sensitive valve that controls the opening degree of the intake passage of an automobile internal combustion engine in an auxiliary manner to a throttle valve, a first electric circuit that heats the temperature-sensitive valve with a high-temperature heater when the circuit is opened, and a first electric circuit that heats the temperature-sensing valve with a high temperature heater when the circuit is opened. a second electric circuit that heats the temperature-sensitive valve with a low-temperature heater; and an atmospheric temperature changeover switch that closes the first electric circuit when the atmosphere is below a predetermined temperature and opens the second electric circuit when the atmosphere is above a predetermined temperature. The heater capacity is controlled according to the atmospheric temperature.

That is, in the above technology, the atmospheric temperature under which the internal combustion engine is placed is set to an arbitrary temperature, and the open state of the bypass passage of the intake passage of the internal combustion engine is changed to two depending on whether the temperature is above or below the set temperature.
It changes in stages.

[Problems to be Solved by the Invention] However, the warm-up operation of an automobile internal combustion engine in cold weather is performed according to the cooling temperature of the internal combustion engine, as shown in Fig. 3 (the warm-up operation time is inversely proportional to Therefore, changing the amount of fuel supplied at the time of starting the internal combustion engine using two-stage control as in the conventional example does not necessarily mean that the warm-up operation of the internal combustion engine matches the temperature conditions. did not become.

As a means for dealing with this, it is conceivable to construct a circuit that obtains the warm-up operation time from the temperature condition using a C-R delay circuit. In order to obtain the warm-up time using the C-R delay circuit, the time limit must range from several tens of seconds to several minutes, so due to the time constant, a 100 [μF] heat-resistant capacitor was used. Even if the resistance value is 1 (MΩ) or more, the resistance value is in the unit of MΩ. However, using a resistance value in the MΩ unit in a vehicle's electrical circuit is not suitable for actual use because of the problem of changes in characteristics due to reductions in other insulation resistances.

In addition, as a means to avoid the above problems, integrated circuits (I
It is also conceivable to perform digital signal processing using C). However, the guaranteed temperature of commonly sold ICs is low, which is not necessarily preferable for use in an engine room like the present device.

SUMMARY OF THE INVENTION Therefore, the present invention aims to eliminate the above-mentioned problems and provide a solenoid valve 111m circuit that does not change its characteristics due to the insulation resistance of the vehicle and can perform warm-up operation that substantially matches the temperature conditions. It is something.

[Means for Solving the Problems] A solenoid valve control circuit according to the present invention includes a positive temperature coefficient thermistor and a solenoid of a solenoid valve controlled by the current of the positive coefficient thermistor.

[Function] By configuring as described above, the temperature of the atmosphere is detected by the PTC thermistor, and this is used as the initial value for warm-up operation, until the predetermined resistance value is reached due to self-heating due to the energization of the PTC thermistor. The time limit is set to match the warm-up characteristics of the internal combustion engine, and the energizing current of the solenoid of the solenoid valve that controls the intake air of the automobile internal combustion engine is determined by the change in resistance value due to self-heating of the positive temperature coefficient thermistor. By controlling the temperature, it is possible to perform warm-up operation that substantially matches the temperature conditions.

[Embodiment] FIG. 1 shows a solenoid valve control circuit according to a first embodiment of the present invention. The solenoid valve controlled by the solenoid valve control circuit is constructed as shown in the sectional view of the solenoid valve in FIG.

First, the solenoid valve shown in FIG. 2 will be explained.

In the figure, a solenoid valve 1 includes a solenoid L wound around a non-magnetic resin bobbin 2, and a resin cover 4 wrapped around the bobbin 2.
is fixed, and a fixed iron core 5 and a movable iron core 6 are arranged in the center hole of the bobbin 2.

The resin cover 4 has a printed circuit board 1 on top thereof.
2 is accommodated, and the accommodated space is filled with epoxy resin. A connection piece 14 electrically connects the solenoid L to circuits such as resistors R1 and R2 and the transistor Q that constitute the electromagnetic valve control circuit mounted on the printed circuit board 12.

Next, a first embodiment of the 'R solenoid valve control circuit will be described.

In the figure, the resistance value of the positive characteristic thermistor P I-1 increases as the temperature rises, as shown in the resistance-temperature characteristic diagram of FIG. 4. Specifically, as the positive characteristic thermistor PH, TDK's PO-D or R3-D is used. A series resistor R is connected to the positive characteristic thermistor PH.
1 and R2 are connected.

The resistor R1 mainly determines the current value flowing through the positive temperature coefficient thermistor PH, and the resistor R2 is a setting resistor that sets the threshold potential of the transistor Q.

The transistor Q and the solenoid L of the solenoid valve 1 are inserted in series, and the switching operation of the transistor Q moves the movable iron core to open and close the solenoid valve 1. Note that the diode D is a flywheel diode that absorbs the electromotive force sent from the solenoid L.

In the above configuration, when the solenoid is energized, magnetic flux is generated in the magnetic circuit consisting of the fixed core 5, the movable core 6, and the yoke 7, and an attractive force is generated between the movable core 6 and the fixed core 5, causing the movable core 6 to It is attracted to the fixed iron core 5 against the urging force of the spring 8. As a result, the inlet 9 communicating with the intake manifold is communicated with the outlet 10 communicating with the negative pressure operated valve, and communication between the atmospheric passage 11 and the outlet 10 is cut off.

Here, when starting the internal combustion engine under certain atmospheric temperature conditions, first, the ignition switch S is turned on. When the internal combustion engine is in a cooled state, the internal resistance of the positive temperature coefficient thermistor PH is small, and the voltage drop across the resistor R2 becomes large, turning on the transistor Q. transistor Q
When the solenoid L of the solenoid valve 1 is turned on, the solenoid L of the solenoid valve 1 is excited by the current from the power source E'. As a result, the movable core 6 is attracted to the fixed core 5 against the urging force of the spring 8, and the inlet 9 communicating with the intique manifold is connected to the outlet 10 communicating with the negative pressure operated valve, and the air passage 11 and the outlet 10 is cut off.

Therefore, when starting the internal combustion engine, the air-fuel ratio is reduced by the electromagnetic valve 1 independent of the throttle valve.

The temperature of the positive characteristic thermistor PH starts from the temperature condition under which the internal combustion engine is started, and the temperature rises due to self-heating of the internal resistance. When the temperature of the positive temperature coefficient thermistor PH increases, its resistance value increases, reducing the voltage drop across the -resistance R2.

When the voltage drop across resistor R2 becomes small and transistor Q is turned off, solenoid L is de-energized and solenoid valve 1 closes inlet 9 communicating with the intique manifold.
The outlet 10 communicating with the negative pressure operated valve and the atmospheric passage 11 are communicated with each other to increase the air-fuel ratio.

At this time, the increase in internal resistance due to self-heating of the positive characteristic thermistor PH determines the turn-off time of the transistor Q, and its characteristics are as shown in the characteristic diagram in Figure 5, which is the characteristic of warm-up operation of the internal combustion engine. By matching these, the startability can be improved.

FIG. 6 shows a solenoid valve control circuit according to a second embodiment of the present invention.

In the figure, the positive temperature coefficient thermistor PH and the solenoid 1
The ignition switch S and the power source E are the same components as in the first embodiment shown in FIG. 1, and their explanation will be omitted.

As can be seen from the characteristic diagram of the positive temperature coefficient thermistor PH in FIG. 4, when its temperature increases from 20° C. to 50° C., its internal resistance increases by 100 times, and it can be used as a switching element.

Therefore, the positive characteristic thermistor PH and the solenoid L of the solenoid valve
The same operation as shown in FIG. 1 can be achieved by connecting the positive temperature coefficient thermistor PH in series and giving the positive temperature coefficient thermistor PH a time setting function based on self-heating and a switching function for turning on and off the solenoid L.

In the second embodiment, the solenoid valve control circuit of the first embodiment is simplified, but a resistor is connected in parallel to the resistors R1 and R2 that set the current of the characteristic thermistor PH of the second embodiment. By connecting a resistor in parallel to the positive temperature coefficient thermistor PH, the delay time until the positive coefficient thermistor PH reaches the switching operation can be arbitrarily changed.

As mentioned above, the solenoid valve control circuit of the present invention can be configured with a positive temperature coefficient thermistor and a solenoid, or a positive coefficient thermistor, a resistor, a transistor, and a diode, which can withstand high temperatures even when placed near an internal combustion engine, etc. But, because it is possible,
It is possible to use an element whose temperature is guaranteed within the range of -40°C to 150°C, and its reliability can be improved.

In addition, the resistance value of a positive temperature coefficient thermistor changes rapidly with temperature, and it is switched depending on the value of the positive coefficient thermistor near room temperature, and is usually 10 (Ω) to 100 (Ω).
Ω), even if an insulation failure occurs due to water fogging in the engine room, there will be little change in characteristics and malfunctions will not occur, making it possible to perform highly reliable control.

[Effects of the Invention] As described above, the present invention uses the detected temperature of the internal combustion engine by the positive temperature coefficient thermistor as the initial value, and uses the change in resistance value due to self-heating due to energization to control the energization of the solenoid valve. If this substantially matches the characteristics of the internal combustion engine of an automobile, warm-up operation that substantially matches the temperature conditions can be achieved.

Furthermore, since the present invention uses a positive temperature coefficient thermistor and a solenoid as its constituent elements, it can withstand high temperatures.
It can be placed near an internal combustion engine or the like. Furthermore, the switching tIA range of a normal positive temperature coefficient thermistor is for switching based on the value of a positive coefficient thermistor near room temperature, and is usually in the range of medium resistance values, so even if an insulation failure occurs, the characteristics will not change due to it. Since there are few errors and malfunctions do not occur, highly reliable control can be performed.

[Brief explanation of drawings]

Fig. 1 shows the solenoid valve control circuit of the first embodiment of the present invention, and Fig. 2 shows the same as Fig. 1! ! A cross-sectional view of the solenoid valve controlled by the valve control circuit, Fig. 3 is an ideal characteristic diagram for warm-up operation, Fig. 4 is a characteristic diagram of a positive characteristic thermistor, and Fig. 5 is the solenoid valve of Fig. 1. A characteristic diagram of warm-up operation by the control circuit, FIG. 6, is a solenoid valve control circuit according to a second embodiment of the present invention. In the figure, 1...Solenoid valve, 2...Solenoid, PH...Positive characteristic thermistor. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts. Patent applicant: Aisin Seiki Co., Ltd. (one person)

Claims (3)

[Claims] (1) A warm-up operation control device for an internal combustion engine for an automobile, which includes a solenoid valve that controls intake air of the internal combustion engine for an automobile, a solenoid that constitutes the solenoid valve, and a positive characteristic thermistor that controls the current of the solenoid. A solenoid valve control circuit characterized in that a positive characteristic thermistor is set to the detected temperature of the internal combustion engine as an initial value, and a change in resistance value due to self-heating due to energization is used to control energization of the solenoid. (2) The electromagnetic valve control circuit according to claim 1, wherein the positive temperature coefficient thermistor and the solenoid are connected in series to control energization of the solenoid. (3) The electromagnetic valve control circuit according to claim 1, wherein a switching element is interposed between the positive temperature coefficient thermistor and the solenoid to control energization of the solenoid.