JPH0458489A - Spark plug for internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate atomization of fuel at the time of low temperature to improve ignition ability by placing a metal sheath type heater on an end face on a side of an ignition part of a main metal jig. CONSTITUTION:On an end face 6 on a side of an ignition part of a main metal jig 4, a metal sheath type heater 7 comprising an electric heating body 9 such as a nichrome wire and an insulator 10 such as magnesia sealed in a circular metallic pipe 8 is placed. Electric conductivity of the heater 7 is performed via a heater power supply electrode take-out part 11 wherein a lead wire 12 is wired along the main metal jig 4 and an insulator 2 and wound around an outer periphery of the insulator 2 on an upper part of the main metal jig 4. The heater 7 facilitates atomization of fuel in a fuel-air mixture which has been sprayed into a combustion chamber of an internal combustion engine so as to improve ignition by spark discharge occurring between a center electrode 3 and an external electrode 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to the structure of a spark plug used between internal combustion engines.

(Prior Art) In the past, various proposals have been made to achieve complete combustion in the combustion chamber and improve the fuel efficiency. Alternatively, a heater is inserted into the ground electrode of the spark gap, and by heating the heater to a high temperature, it prevents carbon contamination from adhering to the surface of the insulator or promotes atomization of the fuel.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional spark plug, when the heater is sheathed in the insulator leg of the spark plug, the wall thickness of the insulator leg, which is a part of the heater, is extremely thin. Therefore, it is not possible to demonstrate sufficient voltage resistance performance against the high voltage applied to the spark plug, and it is also impossible to maintain a sufficient distance between the center electrode of the spark plug and the attached part of the heater. Apply voltage 20~25k
If it is set to V, a flashover will occur with the heater as the ground electrode, the spark plug will not be able to exhibit its original performance, and there is a risk of causing a misfire between the internal combustion engines.

In addition, in the case of a heater introduced into the ground electrode of the spark gap, the ground electrode itself that incorporates the heater always protrudes into the combustion chamber, so it is exposed to the high-temperature combustion gas in the combustion chamber and is further ignited. As the heater itself is subject to severe wear and tear due to repeated cycles, the heater itself is easily damaged by high temperatures or corrosion, and is also susceptible to breakage due to engine vibrations.

Therefore, the present invention aims to promote the atomization of fuel within the combustion chamber without impairing the withstand voltage performance of the spark plug, and to improve the ignition performance, particularly the low-temperature starting performance.

(Means for solving the problem) To this end, a metal sheath type heater, which is made by sealing an electric heating element and an insulating material inside an annular metal pipe, is arranged along the end face of the metal shell on the ignition part side. This is what happens.

(Function) With the above configuration, a metal sheath type heater, which is made by sealing an electric heating element and an insulator inside an annular metal vibrator, is arranged along the end face of the metal shell on the ignition part side. Therefore, by heating this heater to a high temperature, it is possible to promote atomization of the fuel injected into the combustion chamber and to prevent liquid gas from entering the plug firing part along the combustion chamber wall. Complete combustion of the fuel in the combustion chamber becomes possible, and fuel consumption and combustion at low temperatures prevent carbon from adhering to the insulator, and furthermore, the startability thereof can be improved.

(Example) This invention will be further explained with reference to embodiments shown in the drawings.

(1) is a spark plug for an internal combustion engine which is an embodiment of the present invention, and this spark plug for internal combustion IIrw1 has an insulator (2) holding a center electrode (3) at its tip.
and a metal shell (4) having an outer electrode (5) disposed at a position opposite to the tip of a center electrode (3) held by the insulator (2).

An electric heating element (9) such as a nichrome wire and an insulating material (IO) such as magnesia are sealed in an annular metal vibrator (8) on the end face (6) of the metal shell (4) on the ignition part side. The heater (7) is electrically connected to the metal sheathed heater (7) by connecting the lead wire (2) inside the metal shell (4) and the insulator (2). ) along the outer surface of the insulator (2) on the upper part of the metal shell (4).
This is done through.

Since the present invention has the above configuration, when the fuel in the air-fuel mixture is difficult to atomize at low temperatures, the metal sheath type disposed on the end face (6) of the main metal fitting (4) on the ignition part side can be used. By energizing the heater (7), magnesia, etc., is introduced into the annular metal vibrator (8) that constitutes the heater (7). The electric heating element (9), such as a nichrome wire, which is sealed together with the edge (10) generates heat and reaches a high temperature, which promotes atomization of the fuel in the air-fuel mixture injected into the combustion chamber of the internal combustion engine. , the center electrode (3) and the outer electrode (5
), which improves ignition performance due to the spark discharge that occurs between Adhesion to the body (2) etc. can be prevented, and maintenance of the spark plug (1) can be facilitated.

The metal sheath type heater (7) disposed on the end face (6) of the main metal fitting (4) on the ignition part side has one end connected to the pipe (8) within the tubular metal pipe (8).
A nichrome wire (9), which is an electric heating element that is bonded to the inner wall surface and connected to a power line (12) on the other side, is sealed with magnesia (10), which is an insulator, and then bent and formed. This is what happens.

Further, the heater (7) side that is joined to the end surface (6) of the metal shell (4) on the firing section side has at least a flat surface.

(Effects of the Invention) As described above, by arranging a metal sheath type heater on the end face of the metal shell on the ignition part side, it is possible to promote atomization of fuel at low temperatures and improve startability. Since it improves the combustion state of the fuel, it has an excellent effect of preventing the insulator from being contaminated by carbon.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a spark plug for an internal combustion engine which is an embodiment of the present invention, Fig. 2 is a front view of the embodiment from the direction of the outer electrode, and Figs. FIG. 3 is a vertical cross-sectional view of the heater. 1...Spark plug for internal combustion engine 2...Insulator 3
... Center electrode 4 ... Metal shell 5 ... Outer electrode 6 ... End surface 7 ... Heater 8 ... Vibrator 9 ...
...Electric heating element lO...Insulator 11...Heater energizing electrode extraction part 12...Lead wire Patent applicant NGK Spark Plug Co., Ltd. Agent Patent attorney Miyuki Fujiki

Claims (1)

[Claims] A spark for an internal combustion engine in which a metal sheath type heater, which is made by sealing an electric heating element and an insulating material in an annular pipe made of metal, is arranged along the circumferential end surface of the metal shell constituting the spark plug on the ignition part side. plug.