JPH078568U - Discharge gap means for ignition - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a three-electrode type ignition discharge gap means capable of sufficiently lowering a dielectric breakdown voltage and promptly generating a spark. [Structure] A first electrode and a second electrode (center electrode 23 and outer electrode 22) are opposed to each other to form a discharge electrode pair, and a third electrode (center electrode) is formed with a gap wider than the gap length between the electrodes. 21) is provided to form another discharge electrode pair with the first or second electrode and the third electrode, and a voltage is output between the first and second electrodes to generate discharge to generate discharge (ignition). Coil 1
5 side ignition circuit) is provided. Therefore, ions or electrons generated by the spark between the first and second electrodes are directed toward the third electrode, and the dielectric breakdown voltage between the first or second electrode and the third electrode is sufficiently lowered. , The voltage of the stray capacitance between the first or second electrode and the third electrode is not affected by the discharge resistance of the spark between the first and second electrodes, and the spark is also generated between the third electrode. It occurs promptly.

Description

[Detailed description of the device]

[0001]

【Technical field】

 The present invention relates to an ignition discharge gap means which requires a smaller dielectric breakdown voltage (required voltage) than the conventional one for the gap length. Therefore, even if the gap length is increased to improve the ignition performance, the dielectric breakdown voltage will not be as large as in the conventional case. Its fields of use include, for example, ignition of various fuels, and particularly strong combustion types such as lean-burn gasoline engine, spark-assist diesel engine, jet engine, and rocket engine. There are necessary fields etc.

[0002]

[Background technology]

 The sparking phenomenon, which is the most basic function of the spark plug, is expressed by spark discharge characteristics, insulation breakdown voltage, etc., and it is desirable to discharge at a voltage as low as possible. Or, it is desirable to improve the ignition performance by making the gap length as long as possible even with the same dielectric breakdown voltage. On the other hand, in order to stabilize the dielectric breakdown voltage, a three-needle electrode in which a main electrode provided with an auxiliary electrode in the vicinity and a non-main electrode opposed to each other have been known for a long time. It can be applied to spark plugs.

The operation will be described with reference to the ignition circuit shown in FIG. In the figure, C1 is a stray capacitance between the main electrode 6 and the auxiliary electrode 7, C2 is a stray capacitance between the main electrode 8 and the auxiliary electrode 7, and 4 is an ignition device. When the ignition device 4 outputs a high voltage between the main electrodes 6 and 8, first, dielectric breakdown occurs between the main electrode 6 and the auxiliary electrode 7 near the auxiliary electrode 7, and a spark occurs. After that, the spark current charges the stray capacitance C2, and at the same time, some of the electrons or ions that go from the main electrode 6 to the auxiliary electrode 7 go to the main electrode 8 instead of to the auxiliary electrode 7, so that the auxiliary electrode 7 The dielectric breakdown voltage between the electrodes 8 becomes lower than usual. As a result, when the charging voltage of the stray capacitance C2 reaches the lowered breakdown voltage, sparks are generated between the two main electrodes 6 and 8.

[0003]

[Problem] However, since the spark current is limited by the stray capacitance C2, the amount of electrons or ions toward the main electrode 8 is also limited, and the insulation breakdown voltage between the auxiliary electrode 7 and the main electrode 8 does not decrease. There is a first problem that it becomes insufficient. On the other hand, since the charging current of the stray capacitance C2 is limited by the discharge resistance of the spark, the rise of the charging voltage of the stray capacitance C2 is delayed, and the generation of sparks between both main electrodes 6 and 8 is also delayed. There is a second problem.

[0004]

[Purpose of consideration]

 Therefore, an object of the present invention is to provide an ignition discharge gap means capable of sufficiently lowering the dielectric breakdown voltage and promptly generating a spark.

[0005]

[Discussion of proposal]

 That is, according to the present invention, the first and second electrodes are opposed to each other to form a pair of discharge electrodes, and a third electrode is provided at a distance wider than the gap length between the electrodes to form the third electrode. Ignition in which another pair of discharge electrodes is formed by the first or second electrode and the third electrode, and discharge generating means is provided to generate a discharge by outputting a voltage between the first and second electrodes. It is a discharge gap means for use.

[0006]

[First Effect] As a result, the discharge generating means directly generates a spark between the first and second electrodes and directly supplies a spark current, so that the spark current is the first or the second. It is not limited by the stray capacitance between the second electrode and the third electrode. As a result, the amount of ions or electrons traveling to the third electrode is not limited by its stray capacitance, so that the dielectric breakdown voltage between the first or second electrode and the third electrode is sufficiently reduced. The effect of doing is produced.

[0007]

[Second effect] On the other hand, since an external ignition device or the like directly supplies a high voltage between the first or second electrode and the third electrode, the charging current of the stray capacitance between them is increased. Is not limited by the discharge resistance of its first spark. As a result, the charging voltage of the stray capacitance rises faster, and the effect is that a spark is rapidly generated between the first or second electrode and the third electrode.

[0008]

[Best Mode for Carrying Out the Invention]

 In order to describe the present invention in more detail, it will be described below with reference to the accompanying drawings. In the embodiment of FIG. 1, the electrodes 1, 2 and 3 correspond to the above-mentioned first, second and third electrodes, and the discharge generating means 4 corresponds to the above-mentioned discharge generating means. Reference numeral 5 is an ignition device connected from the outside. The discharge generating means 4 is a high voltage output means for outputting a high voltage or a high voltage output means or an ignition device for outputting a high voltage in synchronization with the high voltage output of the ignition device 5.

The operation is as follows. Since the discharge generating means 4 directly generates a spark directly between the electrodes 1 and 2 and directly supplies the spark current, the amount of ions or electrons traveling from the electrode 1 or 2 to the electrode 3 is sufficiently supplied to the electrode 1 or 2. The insulation breakdown voltage between the electrode 2 and the electrode 3 is sufficiently lowered. (First effect) On the other hand, since the external ignition device 5 directly supplies a high voltage between the electrode 1 or 2 and the electrode 3, the stray capacitance charging voltage rises quickly during that time, and the electrode 1 Or, a spark quickly occurs between 2 and the electrode 3. (Second effect)

The embodiment of FIG. 3 is a combination of a hemispherical combustion chamber 24 and the present invention. In the drawing, 9 is a DC-DC converter, 16 is an ignition control means, 25 is a cylinder head, 26 is a piston. Is. The center electrode 23 and the outer electrode (ground electrode) 22 of the spark plug 20 correspond to the above-mentioned first and second electrodes, and the center electrode of the spark plug 21 having no outer electrode corresponds to the above-mentioned third electrode. To do. In this embodiment, the above-mentioned discharge generating means and the external ignition device are combined into one, and both of them output a high voltage at the same time according to the ignition control means 16, but it is better to reverse their voltage polarities. It is preferable that the center electrode of the plug 23 has a negative voltage. The capacity of the capacitor 10 is larger than that of the capacitor 11, the turn ratio of the ignition coil 14 is higher than that of the ignition coil 15, and the higher high voltage is supplied to the spark plug 19 for a longer time.

FIG. 4 is a simplified plan view. In this embodiment, a combustion chamber 17 having a modified bathtub shape is combined with the present invention, and both shafts of the spark plugs 12 and 13 are arranged in substantially the same direction. Although the discharge generating means, the ignition device, the electric wiring, etc. are omitted, they are the same as in the embodiment of FIG. 1 or 3.

The embodiment shown in FIG. 5 is a combination of a wedge-shaped combustion chamber 31 and the present invention. In the figure, 30 is a cylinder head and 32 is a piston. Although the spark plug 28 and the valve 29 appear to be in contact with each other in the figure, the crankshaft and the camshaft are in the direction perpendicular to the drawing, and the spark plug 28 is located on the center line between the two valves 29 which are seen to overlap in the figure. Is stuck. In the case of multiple cylinders, it is possible to prevent the spark plugs 27 and 28 from colliding with other engine components, and thus such two spark plug fixing positions are advantageous. Although the discharge generating means, the ignition device, the electric wiring, etc. are omitted, they are the same as those in the embodiment of FIG. 1 or FIG.

FIG. 6 is a plan view and a front view of the center electrode 64 and the outer electrode 65 of the spark plug 62. The spark plug 62 is the spark plug 20 of FIG. 3, the spark plug 12 of FIG. 4 or the spark plug of FIG. It is a modification of No. 28. The outer electrode 65 has a characteristic shape, and the spark plug 62 can be used in place of the above-mentioned spark plugs.

Finally, in each of the embodiments shown in FIGS. 3 to 5, a two-pole type ignition plug 20, 12 or 28 is used, but these are one-pole type, three-pole type or four-pole type ignition plugs. A plug or a creeping discharge type spark plug may be used. Further, in each of the embodiments shown in FIGS. 3 to 5, since the conventional spark plug which can withstand the harsh conditions of use is used as it is, the durability and the reliability of such an embodiment are also improved. Equipped.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a prior art ignition discharge gap means and the like.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a simplified plan view showing a part of a third embodiment of the present invention.

FIG. 5 is a simplified front view showing a part of a fourth embodiment of the present invention.

FIG. 6 is a plan view and a front view showing an improved spark plug 62 used in the present invention.

[Explanation of code]

 4 Discharge Generating Means 5 Ignition Device 9 DC-DC Converter 16 Ignition Control Means 19 Spark Plugs 17, 24, 31 Combustion Chambers 18, 29, 108 Valves 26, 32 Pistons

Claims (1)

[Scope of utility model registration request] 1. A first electrode and a second electrode are opposed to each other to form a pair of discharge electrodes, and a third electrode is provided at a distance wider than the gap length between the electrodes to form the first or second electrode. Second
Another pair of discharge electrodes are formed by the third electrode and the third electrode, and discharge generating means for outputting a voltage to generate a discharge is provided between the first and second electrodes. Discharge gap means for ignition.