JPS63167077A - Ignition device - Google Patents

Abstract

PURPOSE:To make the certain removement of adhered carbon possible by using a surface discharge plug, and combining an ignition power source whose voltage rise time and discharge duration can attain their fixed values in a discharge waveform with the above-metioned plug. CONSTITUTION:An insulating material 2 is abutedly received in the tip step seat surface 16 of the inner cavity 1a of a main body fitting 1 having engine fastening screws at its tip part, and a conical recess 2f broadening toward its tip is formed on a central part of the end surface 2e of an ignition part of the small diametral part 2b of the insulating material 2. The bottom 2h of the recess 2f is provided with a central electrode tip 3a, and a creeping discharge clearance 4 passing along the recess 2f and a flat surface 2g is formed between the tip peripheral edge 3b of the above-mentioned tip 3a and a tip inner wall 1d forming the earthing electrode of the main body fitting 1, and a surface discharge plug 10 composed in this way is combined with an ignition power source in which voltage rise time is shorter than 10mus and discharge duration is longer than 1ms in discharge waveform to form a desired ignition device.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention prevents smoldering and contamination caused by the adhesion of conductive substances such as creeping discharge type plug carbon used in internal combustion engines, improves ignitability, and improves ignition. Regarding equipment.

[Conventional technology]

Currently, in high-output engines such as outboard motors and racing engines, in order to prevent engine damage caused by spark plug delay and porcelain cracking of the insulator, the center electrode is not provided with the ignition leg in the insulator. and grounding voltage IMt
- A full creeping discharge type plug is used in which an annular creeping discharge gap is formed along the end face of the firing part of the insulator between the inner wall of the tip of the metal shell to be formed. As shown in the figure, since the insulator does not have a ignition leg, it is easy to cause smoldering and staining due to carbon adhesion.
A friend that has the drawbacks of poor contact with mixed gas and poor ignitability.

Therefore, in order to improve the stain resistance and ignitability of the full creepage discharge type defugu, the inventors of the present invention have formed a hemispherical or mortar-shaped end face 2e of the firing part of the insulator 2, as shown in Figures 1 to 2g8. A creeping discharge type plug has already been proposed in which a recess 2fe is provided and a tip portion 3a with a small diameter at the tip of the center electrode 8 is disposed at the bottom 2h of the recess, and the center electrode tip portion 3 is formed. It was necessary to take measures.

[Problem that the invention seeks to solve]

That is, even in the case of the above-mentioned creeping radiation [3! An object of the present invention is to provide an ignition device that further improves the stain resistance and ignitability of a discharge type plug.

[Means for solving problems]

The features of the present invention include a main metal fitting equipped with all engine mounting screws, an insulator housed and fixed so as to come into contact with the top step seat surface of the inner cavity of the main metal fitting, and a hemispherical or mortar-shaped end face of the firing part of the insulator. Create a dent and center it at the bottom of the dent? ! A creeping discharge type plug in which the tip of the pole is provided with a tip portion having a small diameter, and a creeping discharge gap is formed between the center M and the tip end portion of the metal shell through the recess. Then, the voltage rise time in the discharge waveform of this creeping discharge type plug is 10
It is suitable in combination with an ignition power source that has a discharge duration of less than μS and a discharge duration of 1 tn 3 or more.

[Action]

As configured above, the present invention utilizes a creeping discharge type plug and an ignition power source whose discharge waveform has a voltage rise time of 10 μs or less, thereby generating capacitive discharge energy in which sparks slide across the recesses of the insulator and the surface of the end face of the ignition part. Adhering carbon and the like can be reliably removed, and by setting the discharge duration to 21 m 5 or more, the ignitability of the plug can be further improved.

〔Example〕

Embodiments of the present invention will be described below with reference to all the drawings.

Figures 1 and 2 show an embodiment of the creeping discharge type plug used in the present invention, and 10 is the creeping discharge type plug of the present invention, which has an engine mounting screw at the tip and a companion metal fitting. The stepped portion 2a of the ceramic insulator 2 made of high alumina or the like is accommodated in contact with the tip stepped seating surface 1b of the inner cavity 1a of the metal shell 1, and the upper end periphery 1c of the metal shell 1 is crimped using a known crimping method. Fixed. This insulator 2 has a small diameter hole 2b and an intermediate hole 2c, and a large diameter hole 2d for sealing a sealant, and has a small diameter tip 8a1 &: a small diameter hole 2b through which the center electrode 3 is inserted, and a large diameter hole 2d for sealing the sealant. A mortar-shaped or hemispherical recess 2f whose tip expands is provided in the center of the end surface 2e, and an annular flat surface 2 horizontal in the axial direction is provided on the outer periphery of the recess 2f.
g is provided.

The center electrode tip 3a is disposed at the bottom 2h of the recess so as to be flush with or slightly protrude from the bottom, and the tip periphery 8b of the center electrode tip 3a and the ground electrode of the metal shell 1 are entirely formed. It is a creeping discharge type plug in which a creeping discharge gap 4 passing through the recess 2f and the flat surface 2g is formed between the plug and the inner wall 1d of the tip. Further, 6 is a conductive glass sealing material, and 7 is a conductive glass sealing material.
is a resistor, centered within the shaft hole of the insulator 2! While the pole is inserted, the resistor 7 is sandwiched between the conductive gaff sealing material 6 and sealed integrally with the terminal 11[8.

The diameter A of the center electrode tip 3a is 0.2 to 1.8 ml.
φ is preferable from the viewpoint of stain resistance; if it is less than 0.2 mmφ, it will be disadvantageous in terms of wear resistance, and if it exceeds 1.8 ffφ, stain resistance will deteriorate. Further, it is preferable that the depth B of the recess is 0.5H or more, and the diameter C of the opening of the recess is 1.5A (0.8ugφ) or more.If the depth B is less than 0.40, the ignitability will be poor. If the diameter C of the portion is 0.8 ff or less, the ignitability will similarly deteriorate. Further, it is preferable that the dimension of the flat surface is 0.8 ff or more because sparks can jump from the surface of the insulator and ignition performance can be improved.

Further, another embodiment of the creeping discharge type plug used in the present invention may have the structure shown in FIG. That is, the difference between this plug and the above embodiment is that the metal shell 1
A beak-shaped protrusion 1e protruding from the tip face is provided at the tip forming the ground electrode, and an air gap 5 is formed between this protrusion 1e and the flat surface 2g of the end face of the insulator firing part. The spark is generated at the tip periphery 3b of the center electrode tip 8a.
This is a creeping discharge type plug that discharges from the surface through the creeping discharge gap 4 of the recess 2f and the air gap 5 to the inner wall 1f of the metal shell protrusion 1e. The dimension F of the air gap 5 is preferably 0.2 to 1.2 ill; if it is less than 0.2 u, the effect of improving youthfulness cannot be obtained, and if it is more than 1.2 an, the effect of improving youthfulness cannot be obtained. This is not desirable because the voltage increases.

The next creeping radiation? The type plug 10 is used in the ignition system shown in FIG. In the figure, reference numeral 1 denotes an ignition power supply having a discharge duration of 1/72 s or more, and a Furutra unit 12 is used to amplify the pulses of a pulse generator (not shown) that determines the ignition timing. It is composed of an amplifier circuit and a switching circuit that control the power transistor 0N-OFF, and the output of this full-torage unit is connected in series to the 1111 coil of the ignition coil/I/13, and a high 1# voltage is applied to the secondary side high voltage. It is connected to the creeping discharge type plug 10 via a diode 14. 15, the voltage rise time of the discharge waveform is 10 μs
A CDI ignition power source consisting of the following, which connects the ignition coil through a DC-DC converter 16 and a CDI unit 17.
z18, and similarly creeping radiation tl! This CDI ignition power supply 15 forms a parallel circuit with the ignition power supply 11 to superimpose a secondary output on the plug 10.

20 is patch 'J-? tt source.

Therefore, the ignition device of the present invention has a small diameter at the tip of the center electrode (0.2 to 1.8 silk φ is arranged at the bottom of the recess on the end face of the insulator ignition part). Although it has the effect of improving ignition performance, if these problems arise depending on the engine, the above-mentioned creeping discharge type plug may be further used as an ignition power source to provide a spark of the flying component to the CDI ignition electromagnetic conduction with a discharge waveform voltage rise time of 10 μS or more. This further improves the fouling resistance, and following this spark discharge, the engine speed is increased to 200 Or
By superimposing an induction component with a discharge duration of 1 ms or more when the temperature is below pm, the ignitability can be further improved.

Note that the ignition 1 source is not limited to the non-contact type of the above embodiment, but may also be a combination of a contact opening/closing type ignition power source and a CDI power source.The key is that the voltage rise time and discharge duration satisfy the above equation 11. It is fine as long as it is done.

〔Effect of the invention〕

The ignition device of the present invention having the above configuration is suitable for use in engines where even the creeping discharge type plug of the present invention has problems in fouling resistance and ignitability. By combining this with an ignition power supply having a duration of 1 ms or more, even more remarkable effects can be achieved. Incidentally, when the conventional full creepage discharge type plug is combined with the ignition power source of the present invention, it is effective in terms of stain resistance and ignition performance, but the engine malfunctions due to continuous idling operation at -10°C with a rich air-fuel ratio. In evaluations of ignitability in a stain resistance test over a period of time and a starting test at -20°C, it has been confirmed that the total heat is inferior to that of the igniter of the present invention.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the creeping discharge type plug used in the present invention. Figure 1 is a sectional view of the main part of the bladder, and Figure 2 is a sectional view of the ignition part of Figure 81. FIG. 8 is a sectional view of the ignition part of a creeping discharge type plug showing another embodiment used in the present invention, and FIG. 4 is a circuit diagram showing the ignition device of the present invention. 1... Metal shell 1a... Inner cavity 1b... Tip step seat surface 1d... Tip inner wall 2... Insulator 2e...
Firing part end surface 2f...concavity 2g...flat surface 2h.
...Bottom 3...Center [Pole 3a...Tip 4]
... Creeping discharge gap 5... Air gap 1') iIO...
Creeping discharge type plug 11...Ignition power supply 15...C
DI ignition power supply patent applicant NGK Spark Plug Co., Ltd.! s2 figure IF5 figure 14 rlA

Claims (1)

[Claims] (1) A metal shell equipped with an engine mounting screw, an insulator housed and fixed so as to come into contact with the front end seat surface of the inner cavity of the metal shell, and a hemispherical or mortar-shaped recess on the end surface of the firing part of the insulator. and a tip portion of the center electrode having a small diameter is disposed at the bottom of the recess, and a creeping discharge gap is formed between the tip portion of the center electrode and the inner wall of the tip end of the metal shell through the recess. An ignition device comprising: a creeping discharge type plug; and an ignition power source which provides a discharge waveform with a voltage rise time of 10 μs or less and a discharge duration of 1 ms or more, in combination with this creeping discharge type plug.