JPS6235481A - Ignition plug - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to improvements in center electrodes in spark plugs, particularly for internal combustion engines.

(Prior art) Conventionally, the flange of the center electrode of a spark plug has been made of an insulator, as shown in Fig. 9, due to problems in machining the flange itself and problems in fixing the center electrode to the insulator. Small tip diameter hole (G) and large diameter hole (H) separated by step seat [F] in (B)
This spark plug has a shaft hole of 2.5 mm and is separated by more than 0°25 wm from the inner wall of this large diameter hole, and the space is filled with conductive glass (C). Thermal conductivity is an insulating material (At.

0,) thermal conductivity of 210 x 10-1 wm-'
Compared to k-', 5~l0XIO'''''wm''''I
Since k-1 is low, the center electrode (a), which is heated by the use of the engine, is placed in an adiabatic state. Therefore, the temperature of the center electrode (4) rises to A; and exceeds 800° C., thereby causing a preignition phenomenon.

(Problems to be Solved by the Invention) This invention improves the above-mentioned drawbacks of the conventional ones, and dissipates the heat of the center electrode during engine use without changing the protruding dimension of the tip of the insulator. The purpose is to prevent temperature rise and suppress the occurrence of pre-ignition phenomenon.

(Means for solving the problem) For this purpose, in the part other than the center electrode receiving surface that is engaged with the stepped seat of the insulator shaft hole, the axial portion of the flange of the center electrode is fixed in one or more places in the insulator shaft hole. The center electrode is brought into contact with the inner wall, and the surface area of the center electrode flange is increased.

(Function) With the above structure, even if the center electrode is heated by combustion gas when the engine is used, the center electrode will come into contact with the insulator at other parts than the receiving surface, and the surface area of the center electrode will be increased. The thermal conductivity is improved, the heat of the center electrode is dissipated, and the temperature at the tip of the center electrode can be prevented from rising to 800° C. or higher, at which the pre-ignition phenomenon occurs.

(Example) The present invention will be further explained by the embodiment 1 shown in the figure.

fil indicates an insulator made of alumina porcelain or the like, and has a small diameter hole (3) and a large diameter hole (4) at the tip separated by a step seat (2) as the shaft hole. (5) is a center electrode made of nickel alloy or the like with a copper core inside, and a large-diameter collar (6) is formed at one end, and this center electrode is made of an insulator (1
) is inserted into the small diameter hole (3) at the tip, and the collar receiving surface (7) is locked by the step seat (6) of the large diameter hole (4). (9) is a terminal electrode, the tip of which is heat-sealed so as to be electrically connected to the flange (6) via a conductive glass or glass sealing material concave with a resistor sandwiched therein. has been done. a
υ indicates the contact surface between the axial portion (8) of the center electrode collar 8 (6) and the large-diameter inner wall (4) of the insulator shaft hole. ll55
The insulator (1) is fixed inside the inner cavity with a mounting bracket.

In this way, the heat transmitted from the combustion chamber through the center electrode (5) is dissipated from the contact surface Ql of the axial portion of the upper end of the center electrode (5), increasing the temperature at the tip of the center electrode (5). Since the temperature does not rise above 800°C, this spark plug does not cause pre-ignition phenomenon.

The contact surface (11) can be increased as described below, and the surface area of the center electrode collar (6) can also be increased.

(1) Center 1! The pole brim (6) is raised, a constriction is made in the middle, and a plus-shaped groove is cut in the center @ the upper surface of the pole brim tip t13 so that the cut surface is oblique.

(Fig. 3) (11) Fill the center electrode flange (6), make a constriction in the middle, cut out the peripheral part of the upper surface of the center electrode N part tip part 031 diagonally, and make the center electrode tip part α3 into a plus shape. to be excised. (Fig. 4) (lii') Raise the center electrode (6) and further increase the diameter 'f!' in the middle. r. In addition to making it thicker, a plus-shaped groove is cut on the upper surface of the center electrode tip G31 so as not to touch the outer periphery.

(vJS diagram) (1) Fill the center electrode flange (6) with earth and cut a vertical groove to make the center electrode flange (6) gear-shaped. (No. 61+) (V) The center electrode flange (6) is raised, and its diameter is made to be in contact with the inner wall of the insulator shaft hole up to the middle, and then the diameter is made thinner. (Fig. 7) (Effect of the invention) Since the structure is as described above, each center ridge and pole are in contact with a highly thermally conductive insulator, and by increasing the surface area, each ignition As shown in Figure 8, when the plug is used in an engine, the temperature of the center electrode tip (7) is suppressed to 20 to 70 degrees Celsius lower than that of conventional spark plugs, making it possible to suppress the occurrence of the pre-ignition phenomenon. can.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure 1 shows a vertical cross-sectional view showing an embodiment of the spark plug of the present invention, Figure 2 is an enlarged view of the main part of Figure 1, and Figures 3 to 7 are views of the same. FIG. 3 shows (a) a plan view and (b) a front view of each embodiment of the structure of the flange portion of the center electrode according to the invention. Fig. 8 is a performance comparison diagram of various companies, and Fig. 9 is an enlarged view of the main parts of the conventional one. 1...Insulator, 2...Step seat, 3...Small diameter hole, 4...
...Large diameter hole, 5... Center electrode, 6... Center electrode flange, 7... Flam receiving surface, 8... Axial portion of the flange, 9... Terminal electrode, 10 ...Glass sealing material, 1
1...Contact surface between the center electrode flange and the inner wall of the insulator shaft hole, 1
2... Attachment fittings. Patent Applicant Agent Patent Attorney Miyuki Fujiki No. 1
Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (2)

[Claims] (1) An insulator fixed in the inner cavity of the mounting bracket, the shaft hole of this insulator having a small diameter hole and a large diameter hole at the tip separated by a stepped seat, and a receiving part for the flange of the center electrode. In a spark plug which is inserted into the small diameter so that the surface is locked with the stepped seat, and the upper end of the flange is sealed with a glass seal together with the terminal electrode, the axial direction of the flange other than the receiving surface of the center electrode A spark plug whose portion is at least locally in contact with the inner wall of a large diameter hole of an insulator. (2) The spark plug according to claim 1, wherein the center electrode flange portion is provided with appropriate recesses and grooves to increase the surface area.