JPS6127588B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an internal combustion engine ignition system using a spark plug, and more specifically, to a device that generates spark discharges at a plurality of different positions on the spark plug at a single ignition timing. The present invention relates to an internal combustion engine ignition device with improved ignitability.

Prior Art In recent years, automobile engine ignition systems are required to have reliable ignition performance with air-fuel mixtures that have undergone thin or large amounts of exhaust gas recirculation in order to purify exhaust gas, and misfires occur, especially in automobile engines equipped with catalytic converters. The large amount of unburned gas may cause the catalyst to burn out, so it is important to improve ignitability.

Problems to be Solved by the Invention Conventionally, attempts have been made to overcome this difficulty by increasing the gap between the electrodes of a spark plug to prevent the deterioration in ignitability due to the flame-extinguishing action of the electrodes, but this requires a high spark discharge voltage, which requires a strengthened power supply. The disadvantage is that the cost increases because it needs to be combined with Also, a spark plug has been proposed that has multiple spark discharge gaps arranged in series to emit sparks at multiple locations, as shown in Figure 1, but the structure of the spark plug itself is complex and unsuitable for mass production, making it difficult to use. There was also a problem. Furthermore, attempts have been made to improve ignitability by applying high voltage to the spark plug multiple times to generate multiple spark discharges, but the discharge gap is long, about 1000 μs, and the spark generated at one ignition timing is difficult to achieve. In addition to the small number of sparks, there was no consideration given to the direction of the sparks spreading radially, etc., so sparks with good ignition conditions do not occur during the 1000 μs ignition timing of the internal combustion engine, except at startup and in extremely low rotational speed ranges. The effect of producing electric discharge was low.

The present invention can produce a large number of sparks in different directions at the spark plug at a single ignition timing, and the ignition performance of the internal combustion engine is significantly improved.Moreover, the structure is simple and the cost increase is small. The purpose is to provide an ignition device.

Means for Solving the Problems The internal combustion engine ignition device of the present invention includes a circuit device that applies a plurality of pulsed high voltages to the spark plug at intervals of 50 μs to 500 μs during ignition timing, and a circuit device that applies a plurality of pulsed high voltages to the spark plug at intervals of 50 μs to 500 μs during ignition timing, In combination with an air gap multi-pole spark plug with two or more outer electrodes,
The spark discharge is caused to occur in the gap between the electrode surfaces of the multi-pole spark plug at different times.

Effect The present invention will be explained in detail below with reference to the drawings.

In spark plugs, normally a single spark is generated between the electrodes for each spark plug, as shown in Figure 2, and it is difficult to simultaneously generate multiple spark discharges at different positions between the same electrodes. It was thought that

Through experiments, the inventors applied a pulsed high voltage between the spark plug electrodes at certain intervals (in this experiment,
When applied multiple times at intervals of 100 μs),
It was discovered that spark discharge does not occur at the location where the discharge occurred first when the next pulsed high voltage is applied, but spark discharge occurs at other locations.

In this phenomenon, as shown in FIG. 8, spark discharge first occurs in the space A between the spark plug electrodes where the ion density is highest. In the discharge space A, a plasma state in which positive and negative ions are mixed suddenly occurs, and after the spark discharge ends, the plasma density in the discharge space A rapidly decreases due to consumption, and as shown in the figure, the ion density also decreases in the spark discharge. It decreases more sharply than in spaces B and C without. 500μs to 1000μs without applying the next high voltage
After s elapse, the ion densities in all spaces A, B, and C drop to the same level as before the spark discharge. However, when a pulsed high voltage (with an interval of 100 μs) is again applied between the spark plug electrodes when this ion density remains to some extent, spaces B and C with a large amount of remaining ions change to space A with a small amount of remaining ions.
The state becomes a state where the ion density is higher {B, C>A (in this case, B>C)}. Therefore, the electric field strength in space B becomes stronger than in other spaces C and A, and spark discharge inevitably occurs in space B.

Furthermore, after the spark discharge in space B ends, the plasma density in discharge space B rapidly decreases due to consumption, and as shown in the figure, the ion density also decreases more rapidly than in spaces A and C where there is no spark discharge. Eventually, the ion density in all spaces A, B, and C decreases to the same level as before the spark discharge. When a pulsed high voltage (at intervals of 100 μs) is again applied between the spark plug electrodes when a certain amount of this ion density remains, space C with a large amount of ions remaining becomes space A and space B with a small amount of ions remaining. The state becomes a state where the ion density is higher {C>A>B}. The electric field strength in space C is stronger than in spaces A and B, and spark discharge inevitably occurs in space C. Continuing this experiment, it was confirmed that when a pulsed high voltage was applied multiple times at intervals of 100 μs between the spark plug electrodes, many spark discharges were generated at various locations as shown in FIG.

Embodiment FIG. 6 shows an embodiment of an internal combustion engine ignition system according to the present invention.

1 is a constant voltage electrode, 2 is a DC-DC converter, 3 is a pulsed high voltage generating circuit that applies multiple pulsed high voltages to the spark plug at intervals of 50 μs to 500 μs during the ignition timing, and 4 is shown in Figure 3. This is an air gap multi-pole spark plug in which two or more (three in this embodiment) outer electrodes are arranged radially around a center electrode as shown. In the case of such a multi-pole spark plug 4, the pulse-like high voltage generating circuit 3 generates a pulse-like high voltage as shown in the time chart shown in FIG. 7 during one ignition timing of the internal combustion engine, and When applied to the ignition plug 4, spark discharge occurs at a large number of outer electrodes, as described above.

For reference, if the spark plug is a creeping discharge spark plug as shown in Figure 4, a large number of radial spark discharges will occur, and as shown in Figure 5, the center electrode will be thicker than a certain level and the outer electrode will be thicker. A single spark plug generates sparks in a cylindrical shape, but the spark plug is best used as an air gap multi-pole spark plug 4, in which two or more outer electrodes are arranged radially around a center electrode. Experiments have shown that it has good ignitability.

In order to improve the ignition performance of a multi-pole spark plug, it is better to generate as many spark discharges as possible at various positions, but the pulsed high voltage generation interval of the pulsed high voltage generation circuit 3 is limited to about 50 μs to 500 μs. It is preferably 70 μs to 400 μs. 50μs
Below 500μ, many spark discharges are unlikely to occur.
s or more, the number of spark discharges that occur during one ignition timing decreases, and the rate of contribution to improving ignition performance is low.

Furthermore, it has been found through experiments that if the center electrode is polarized, a large number of spark discharges can be generated at different positions with a shorter pulse-like high voltage than in the case of polarity, and ignition performance is improved.

Effects of the Invention The present invention has a circuit device having the above configuration and applying a plurality of pulsed high voltages to the multipolar spark plug at intervals of 50 μs to 500 μs during the timing of the multipolar spark plug. A plurality of spark discharges occur at different positions at the multi-electrode ignition timing, and the contact surface between the air-fuel mixture and the multi-electrode spark plug spark is expanded, and the ignition performance of the internal combustion engine is equally improved. Moreover, the structure is relatively simple and the increase in cost is small.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional spark plug, Figure 2 is a side sectional view of a conventional spark plug.
FIG. 3 is a front view showing the state of single spark discharge of a conventional spark plug, FIG. 3 is a front view showing the state of spark discharge of a multi-polar spark plug by the internal combustion engine ignition system according to the present invention, and FIG. 4 is a creepage view. FIG. 5 is a front view showing the state of spark discharge of a discharge spark plug, FIG. 5 is a front view showing the state of spark discharge of a spark plug in which the center electrode is thicker than a certain level and the outer electrode is one, and FIG. 6 is a front view showing the state of spark discharge according to the present invention. A configuration diagram showing an example of an internal combustion engine ignition system, FIG. 7 is a time chart of the pulsed high voltage of the multipolar spark plug shown in FIG. 3, and FIG. This is a time chart of ion density. In the figure, 1...constant voltage power supply, 2...Dc-Dc converter, 3...pulse high voltage generation circuit, 4...multipole spark plug.

Claims (1)

[Claims] 1. A circuit device that applies a plurality of pulsed high voltages to a spark plug at intervals of 50 μs to 500 μs during ignition timing, and two or more outer electrodes arranged radially around a center electrode. What is claimed is: 1. An internal combustion engine ignition system characterized by combining a multi-polar spark plug with an air gap, and generating spark discharge in gaps between electrode surfaces of the multi-polar spark plug that are different a plurality of times. 2. The internal combustion engine ignition device according to claim 1, wherein the center electrode of the spark plug is polarized.