JPS593195Y2 - Internal combustion engine ignition system - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ignition system for an internal combustion engine. Various ignition methods have been proposed to improve the ignition performance of an internal combustion engine, and one of them is a multi-ignition method.

Multi-ignition is an ignition method that increases the chances of ignition by emitting sparks repeatedly during each ignition, and its circuit configuration is shown in FIG.

In FIG. 1, 1 is an interrupter, 2 is a control circuit, 3 is an output circuit, 4 is a battery, 5 is an ignition switch, and 6
is the device I distributor (power distribution section), and 7 is the spark plug.

The interrupter 1 is similar to the interrupter found in a normal ignition system, and the breaker point 9 opens and closes in response to the rotation of the test repeater cam 8, and interrupts the control current to the control circuit 2 at a predetermined timing. do.

The control circuit 2 stops energizing the ignition primary coil 10 provided in the output circuit 3 when the control current is cut off.

Therefore, a high-voltage ignition current is generated in the ignition secondary coil 11 due to mutual induction, and this is transmitted to the distributor 6.
Power is distributed to each spark plug 7 via the spark plug 7 to cause spark discharge.

In this device, the ignition secondary current of the secondary coil 11 is captured by the feedback coil 12, and the second primary coils 13a and 13b alternately repeat the interruption of the primary current. As shown in Figure 2,
This causes the secondary coil 11 to generate an induced electromotive force that oscillates over a short period of about 10 m5ec.

By doing so, multiple spark discharges can be obtained for each ignition, which increases the chances of ignition and improves ignition performance.

However, as is clear from the above explanation, according to this device, the ignition energy per spark discharge is the same as that of conventional ignition devices, so for example, NOx
When performing EGR, which mixes a large amount of exhaust gas into the intake air in order to suppress the generation of harmful substances such as, or ultra-lean combustion with an air-fuel ratio of 18 to 19 or more, sufficient ignition performance cannot be achieved. Reference SAE that had the problem
paper760266゜The present invention provides an ignition device for an internal combustion engine that solves the above problems by forming a plasma ignition circuit that provides high ignition energy in addition to multiple ignition circuits.

Hereinafter, the present invention will be explained based on illustrated embodiments.

In FIG. 3, 14 is a plasma ignition circuit.

Since the other parts are the same as those in FIG. 1, the same parts are denoted by the same reference numerals.

The plasma ignition circuit 14 is composed of a DC/DC converter 15, a resistor 16, a capacitor 17, an inductor coil 18, a diode 19, etc., and the plasma ignition circuit 14 is composed of a DC/DC converter 15, a resistor 16, a capacitor 17, an inductor coil 18, a diode 19, etc. Capacitor 1 is damaged due to a large current of about 3000 V.
7 is charged, and this charged charge (high-voltage charge energy) is discharged to the ignition plug 7 during spark discharge, thereby imparting strong ignition energy.

In this case, the discharge time of the high-voltage charge energy can be adjusted according to the time constant determined mainly by the capacitance of the capacitor 17 and the inductance of the inductor coil 1B. If the power is set so that the time and discharge time due to high-voltage charge energy almost match, a large current that is high-voltage charge energy will be supplied at once at the same time as the first spark discharge, as shown in Figure 4. (shaded area), a strong ignition flame kernel is obtained.

This is because the plasma-like gas generated between the gaps of the ignition plug 7 during spark discharge expands upon being supplied with high-voltage charge energy (plasma discharge), and this high-temperature plasma-like gas provides extremely good fuel ignitability. It will become.

Then, after the plasma discharge, a spark discharge due to multiple ignition occurs.

Therefore, for example, as shown in FIG.
The intake passage 21 is formed in the tangential direction to give swirling to the intake air, and the injection valve 2 is formed along the swirling direction.
2 or an engine in which fuel is injected through the 6th
As shown in the figure, in an engine in which a rich mixture is sucked through an intake passage 23 formed in the tangential direction to give swirling, and a lean mixture is sucked through another intake passage 24, the injected fuel flow Alternatively, by arranging the spark plug 7 on the downstream side of the rich mixture air flow and performing multi-ignition by injecting the high-voltage charge energy, a strong flame kernel 25 based on plasma ignition and a flame kernel due to subsequent spark discharge can be generated. 2
6 spreads into the combustion chamber 20 due to the swirling flow, not only the ignitability is improved, but also good combustion with fast flame propagation can be expected.

Therefore, when EGR is activated or ultra-lean combustion is performed, fuel consumption can be reduced without impairing engine performance.

FIG. 7 shows another embodiment of the present invention, and is an example in which the plasma discharge time is changed depending on engine operating conditions.

In this example, as illustrated, the iron core 28 of the inductor coil 27 is moved in and out of the coil 27 to change the inductance, thereby controlling the discharge time of the high voltage charge energy.

As shown in FIG. 8, the iron core 28 is moved via a solenoid actuator 29, and the actuator 29 usually moves the iron core 2B into the coil 21 based on the repulsive force of a coil spring 29a. The iron core 2B is inserted and held, and when the solenoid 29b is energized, the iron core 2B is pulled out to the outside of the coil against the repulsive force of the coil spring 29a.

Energization to the solenoid 29b is regulated via a switch 30 that opens and closes in conjunction with a load detection means (not shown) (air flow meter, intake pressure sensor, etc.). In this case, the switch 30 closes when the engine load increases to a certain extent. is set to

By doing this, the iron core 28 is pulled out from the coil 27 as shown in FIG. 9A in the high-load operating range, so that
The inductance of the coil 27 is reduced, the circuit time constant is reduced, and the discharge time tx of the high voltage charge energy is shortened as shown in FIG. 10A.

Therefore, in relation to multiple ignition, ignition discharge characteristics as shown in FIG. 4, for example, can be obtained.

On the other hand, in the low to medium load operating range, the iron core 28 is inserted into the coil 27 as shown in FIG. 9B, so the coil 27
The inductance of increases and the circuit time constant increases,
As shown in FIG. 10B, the discharge time tx of the high-voltage charge energy becomes longer.

Therefore, as shown in FIG. 11, the discharge characteristics of the entire device are such that high-voltage charge energy is dividedly supplied for each of the first several spark discharges due to multi-ignition.

As a result, in high-load operating ranges where both ignition and combustion are generally good, a powerful flame kernel is formed based on a single injection of high-voltage charge energy, contributing to engine output performance, and in low- to medium-load operating ranges. In this case, reliable ignition performance is ensured based on the generation of a large number of ignition flame kernels to which high-voltage charge energy is applied.

In addition, in FIGS. 7 and 8, 31 is the plasma ignition circuit 14.
This is a changeover switch that regulates the power supply to the (DC/DC converter 15), and this changeover switch 31 is set to open in a high-speed operating range, for example, in conjunction with speed detection means such as a rotation speed sensor (not shown). It's okay.

This is because, in high-speed operating ranges, sufficient ignition and combustion characteristics may be obtained only by the spark discharge of multi-ignition.

As described above, according to the present invention, a plasma ignition circuit is formed in addition to the multi-ignition circuit, and a large current and high voltage charge energy is applied at the time of multi-ignition spark to generate a powerful ignition flame nucleus. Even when EGR or ultra lean combustion is applied, reliable ignition and stable combustion can be obtained, and therefore fuel efficiency can be improved without impairing engine performance.

In addition, by controlling the discharge time of the high-voltage charge energy as described above, efficient multiple ignition can always be performed in accordance with the engine operating conditions.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of the multi-ignition system, and FIG. 2 is a discharge voltage characteristic diagram thereof. FIG. 3 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 4 is a discharge current characteristic diagram thereof. FIG. 5 and FIG. 6 are explanatory diagrams of the effects of the embodiment, respectively. FIG. 7 is a circuit configuration diagram of another embodiment of the present invention, FIG. 8 is a schematic diagram showing an example of its control method, and FIG. 9 is a diagram showing A and B.
are explanatory diagrams showing the variable states of the inductor coil in the same embodiment, and FIGS. 10A and 10B are respectively FIG. 9A.
, B. FIG. 11 is a characteristic diagram showing the discharge characteristics of the embodiment device corresponding to FIGS. 9B and 10B. DESCRIPTION OF SYMBOLS 1... Interrupter, 2... Control circuit, 3... Output circuit, 6... Test repeater (power distribution part), 7...
Spark plug, 14... Plasma ignition circuit, 17... Capacitor, 18... Inductor coil, 27... Inductor coil (variable).

Claims (1)

[Claims for Utility Model Registration] 1. A multi-ignition circuit that supplies a plurality of spark discharge currents to a spark plug for each ignition, and a plasma ignition circuit that also supplies high-voltage charge energy. ignition system for internal combustion engines. 2. The plasma ignition circuit includes at least an inductor coil and a capacitor for charging high-voltage charge energy, and is configured to discharge the high-voltage charge energy over a predetermined time according to a time constant determined by the inductance of the inductor coil and the capacitance of the capacitor. An ignition system for an internal combustion engine according to claim 1 of the utility model registration claim, characterized in that: 3. Inductance is a variable inductor coil consisting of a coil and an iron core that can move freely inside and outside the coil.Through a control means that moves the iron core according to engine operating conditions,
Utility model registration claim 2, characterized in that the inductance is reduced in response to an increase in engine load.
An ignition system for an internal combustion engine as described in paragraph. 4. The internal combustion engine according to any one of claims 1 to 3 of the claims for registration of a utility model, characterized in that the plasma ignition circuit is linked with a load detection means and is cut off in a high-load operating range. Engine ignition system. 5. The internal combustion engine according to any one of claims 1 to 4 of claims 1 to 4, wherein the plasma ignition circuit is linked to a speed detection means and is shut off in a high-speed operating range. igniter.