JPH0244061Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition system for a gasoline engine that has a function to stop the engine due to insufficient amount of fluid such as engine oil, radiator cooling water, or brake fluid.

In general, if you continue to drive a gasoline engine with insufficient engine oil or radiator cooling water, problems such as engine seizure or reduced output will occur, and if the brake fluid level becomes abnormally low, the brakes will be damaged. The problem is that your hearing becomes worse.

This invention was developed with these points in mind, and is designed to forcibly stop the engine and issue a warning when fluid levels such as engine oil, radiator cooling water, or brake fluid run out. The present invention provides an ignition system for a gasoline engine.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the ignition system for a gasoline engine according to the present invention, as shown in FIG. 1, a self-trigger transistor main ignition circuit A and a liquid level detection sensor 1 detect, for example, an insufficient amount of engine oil 2. and a liquid amount shortage detection circuit B, which forcibly short-circuits the primary side P of the ignition coil IGC in the main ignition circuit A when the main ignition circuit A is activated.

Transistor main ignition circuit A uses a self-trigger system, but shows the basic circuit configuration.The field is rotor R, which rotates in synchronization with the engine and has a permanent magnet MG attached to its periphery, and the primary ignition coil IGC. As a kind of alternating current generator with side P as an armature and a power supply, a low voltage alternating current is generated in the primary circuit of the ignition coil IGC when the main transistor Q1 is turned on, which is controlled by switching according to the change in the voltage induced on its primary side P. is applied, and when the primary current is turned off, the primary current is abruptly cut off to generate a high voltage on the secondary side S of the ignition coil IGC by electromagnetic induction, and a spark is sent to the ignition plug G. In addition, as a control circuit for the main transistor Q1 in such a transistor main ignition circuit A, as shown in the figure, a control transistor Q2 ( The base of the main transistor Q1 and the collector of the control transistor Q2 are connected by the resistor R2, and the ignition coil IGC
Voltage dividing resistors R3 and R4 connected in parallel to the primary side P of
The base control of the control transistor Q2 is performed in accordance with the potential at the voltage dividing point a at the voltage dividing point a. Note that a capacitor C1 for stabilizing the base voltage is provided in parallel with the resistor R4.

In addition, the liquid level shortage detection circuit B includes a short circuit consisting of a thyristor SCR connected in parallel with the primary side P of the ignition coil IGC in the transistor main circuit A;
The primary side P of the ignition coil via the liquid level detection sensor 1
A gate circuit that controls the gate of the thyristor SCR according to the potential at a voltage dividing point b of resistors R6 and R7 connected in parallel with the ignition coil IGC.
A diode D1 and a light emitting diode LED are connected in parallel to the primary side P via the liquid level detection sensor 1.
and a resistor R5, a bypass capacitor C2 connected between the connection point c between the light emitting diode LED and the resistor R5, and the point b, and a capacitor C3 connected in parallel to the resistor R6.
It is made up of. The liquid level detection sensor 1 is composed of, for example, a float equipped with a permanent magnet and a reed switch. When the float falls below a certain level in response to a drop in the liquid level, the reed switch is turned on and the liquid is turned on. For example, those that detect insufficient quantity are used, which have a switch structure in which the detection contact turns on and off depending on the level of the liquid level. In addition, in parallel with the ignition coil IGC primary side P,
Stop switch STP/SW that allows you to stop the engine at will by closing the contact.
is provided.

Therefore, in the gasoline engine ignition system according to the present invention configured as described above, when the liquid level of the engine oil 2 is sufficient and the detection contact of the liquid level detection sensor 1 is in the OFF state, the main ignition Normal operation in circuit A is achieved. That is, when the rotor R rotates and an alternating voltage is induced on the primary side P of the ignition coil IGC, first, when the collector C side of the main transistor Q1 becomes a positive potential, a base current flows through the resistors R1 and R2, and the main transistor Q
1 turns on, thereby causing primary current to flow through the ignition coil IGC. Next, the voltage between the collector C and emitter E of the main transistor Q1 rises, causing the resistance R to rise.
3. When the potential at point a divided by R4 reaches the trigger potential of the control transistor Q2, the control transistor Q2 turns on, thereby shorting the base side of the main transistor Q1 and turning it off. The primary current of the ignition coil IGC is abruptly cut off, and a high voltage pulse is induced in the secondary side S of the ignition coil, causing a spark to fly to the ignition plug G.
In this case, a voltage having the characteristics shown in FIG. 2a will be induced on the primary side P of the ignition coil IGC.

Furthermore, when the liquid level of the engine oil 2 is insufficient and the detection contact of the liquid level detection sensor 1 is turned on, the SCR gate circuit in the liquid level shortage detection circuit B is closed, thereby turning off the main transistor Q1. When a negative voltage is induced on the primary side of the ignition coil IGC, current flows to the gate of the thyristor SCR through the detection contact of the liquid level detection sensor 1 and the resistor R7, making it conductive and short-circuiting the primary side of the ignition coil IGC. As a result, the spark plug G on the secondary side S misfires, and the ignition operation of the engine is forcibly stopped. At this time, the voltage induced on the primary side P of the ignition coil IGC has characteristics as shown in FIG. 2b.

Furthermore, when the detection contact of the liquid level detection sensor 1 is turned on, the LED alarm circuit is closed, and the positive voltage induced on the primary side of the ignition coil IGC according to the rotation of the rotor R causes Current flows through the alarm circuit and the light emitting diode LED lights up. At this time, from the time the detection contact of the fluid level detection sensor 1 is turned on until the engine completely stops, the light emitting diode LED will flash on and off in synchronization with the rotation of the engine, thereby issuing a warning that the fluid level is insufficient. will be emitted. Note that even when the engine is started, if a lack of liquid level is detected by the liquid level detection sensor 1, the lack of liquid level detection circuit B
The short circuit in the SCR works and no spark is emitted to the spark plug G, so the engine does not start.
At this time, since the rotor R is rotated by the starter, the light emitting diode LED blinks and a warning is issued, thereby allowing the driver to easily understand the reason why the engine does not start.

In such an ignition device for a gasoline engine, it is preferable to use a high-intensity LED as the light emitting diode to enhance the warning effect. For example, high-brightness LEDs emit light with a brightness that is about two orders of magnitude higher than that of ordinary LEDs, and even with a current of about 10 μA, the light emission can be clearly seen in a darkened environment.

However, if a highly sensitive and high-intensity LED is used, it is conceivable that the LED will emit light due to the induced current in the circuit. In that case, in particular the resistors R5, R6,
The L and C components of R7 become a problem, and each of these resistances R
5, R6, and R7 form a closed loop for the light emitting diode LED, and if an induced electromotive force is generated, a current flows through the loop and lights up the LED. Therefore, in the present invention, a bypass capacitor C2 is provided to prevent the induced current generated in the resistors R5 and R7 from flowing to the light emitting diode LED, and the induced current generated in the resistor R6 is absorbed by the capacitor C3. ing. Note that the capacitor C3 also has the function of stabilizing the gate voltage to prevent malfunction of the thyristor SCR.

In addition, as shown in Figure 3, the thyristor SCR
diode D on the side of the circuit and its gate circuit.
2 to make the alarm circuit for the light-emitting diode LED independent, the induced current will not be much of a problem since only the resistor R5 is connected to the circuit, and the capacitor C2 in Figure 1 can be replaced with Although this can be omitted, on the other hand, with such a configuration, a decrease in insulation resistance due to deterioration due to long-term use of the liquid amount detection sensor 1 becomes a problem.

In other words, since the liquid level detection sensor 1 is installed in a liquid such as engine oil 2, it is used under conditions where the terminals etc. are likely to deteriorate due to oil seepage. When the insulation resistance decreases somewhat due to deterioration, the potential at the connection point d decreases, and as a result, the diode D1, the light emitting diode
When the potential applied to the LED and the resistor R5 becomes relatively high and exceeds the inherent forward voltage drop value of the light emitting diode LED and the diode D1, a phenomenon occurs in which the light emitting diode LED is erroneously lit. However, in the present invention, without providing the diode D2 as shown in FIG.
Resistor R6 in the gate circuit of thyristor SCR,
By using R7 and configuring it to be connected in parallel to the diode D1, the light emitting diode LED, and the resistor R5, when a forward voltage is applied to the light emitting diode LED, the liquid level detection sensor 1 Even if the insulation resistance deteriorates to some extent and a leakage current occurs in the liquid level detection sensor 1 part, this leakage current can be passed using the resistors R6 and R7 of the gate circuit, so the voltage of the light emitting diode LED part etc. This suppresses the rise in temperature to prevent the light emitting diode LED from accidentally lighting up. That is, the light emitting diode LED and the diode D1
Each has its own forward voltage characteristics, and current will not flow unless the voltage is higher than that.
Not providing the diode D2 in FIG. 3 is more effective in preventing a decrease in insulation resistance caused by deterioration of the liquid amount detection sensor 1.

As described above, in the ignition system for a gasoline engine according to the present invention, when a shortage of liquid such as engine oil or radiator cooling water is detected by the liquid level detection sensor, the primary side of the ignition coil is short-circuited to start the engine. In addition to forcibly stopping the engine, the alarm is activated by the primary output voltage of the ignition coil until the engine stops, especially when a high-intensity LED is used as the alarm. To prevent erroneous lighting of an LED due to an induced current in the circuit and erroneous lighting of a light emitting diode LED due to a decrease in insulation resistance due to deterioration of a liquid level detection sensor 1, etc., by using a gate resistance circuit of a thyristor for stopping an engine. Can be done.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram showing an embodiment of the ignition system for a gasoline engine according to the present invention, FIG. Similarly, FIG. 3b is a diagram showing voltage characteristics induced on the primary side of the ignition coil at the time of misfire, and FIG. 3 is an electrical wiring diagram showing another example of the configuration of the liquid amount shortage detection circuit. A...Transistor main ignition circuit, B...Low level detection circuit, LGC...Ignition coil, G...Spark plug, Q1...Main transistor, Q2...Control transistor, 1...Liquid level detection sensor.

Claims (1)

[Scope of utility model registration request] The voltage induced on the primary side of the ignition coil in response to the rotation of the rotor in synchronization with the engine is divided by a resistive voltage divider circuit, and the voltage is connected in series to the primary side of the ignition coil according to the potential at the voltage dividing point. In the ignition system of a gasoline engine, which turns off the main transistor to cut off the primary current of the ignition coil, thereby producing a spark in the ignition plug installed on the secondary side of the ignition coil, a lack of fluid is detected. A gate circuit consisting of a liquid level detection sensor that closes its detection contact and a voltage dividing resistor is formed through the detection contact of the liquid level detection sensor, and is triggered according to the potential of the voltage dividing point of the voltage dividing resistor to ignite. A thyristor circuit that misfires the spark plug by short-circuiting the primary side of the coil, and a light emitting diode in response to a reverse voltage that does not contribute to ignition induced on the primary side of the ignition coil through the detection contact of the liquid level detection sensor. Each resistor in the closed loop formed by the alarm circuit for lighting and the parallel circuit of the alarm circuit and the gate circuit prevents the induced current generated by each resistor from flowing to the light emitting diode. An ignition device for a gasoline engine characterized by comprising a bypass capacitor circuit that short-circuits a resistor.