JPS6028191A - Flat sheet type spark plug of long reach - 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 The present invention provides an internal combustion engine with a mounting screw diameter of 10.12°111f.
This invention relates to a flat sheet type spark plug which is a long reach type with a length of the cylinder head embedded part of 19 cm or more, and which is screwed onto the cylinder head via a gasket tracker.

As shown in FIG. 1, in a conventional spark plug for an internal combustion engine, a porcelain insulator 3 holding a center electrode 2 is sealed and fixed in the inner cavity of a metal shell 21, and the metal shell is screwed onto a cylinder head 26. In the case of 21 mounting screw diameter 14.12ff, the length of the cylinder head (reach) L
are respectively 12.7a and 19πm, and 12.7mm is mainly used when the thread diameter is between 10 and 10mm. Furthermore, the reach portion is almost completely threaded and is fastened to the cylinder head via the gas get 5.

By the way, if the long reach and thread diameter between 19 mentioned above is 1
In 011IIt, the strength of the metal shell deteriorates as the wall thickness becomes thinner due to the root diameter of the spark plug, which is fully threaded in the same way as the reach 19 sugar, and the airtightness between it and the insulator is deteriorated due to distortion during tightening. It tends to be incomplete, and in severe cases there is a risk of breakage.

Furthermore, extending the insulator in the axial direction within a limited range in the radial direction tends to cause distortion during firing, which reduces productivity. Furthermore, the long threaded portion naturally makes it extremely troublesome to attach and detach the plug. In particular, these trends have a greater influence as the thread diameter becomes smaller, and it is even more difficult to satisfy the above performance when a conventional thread is provided for a long reach plug with a thread diameter of 10 mm.

The present invention has been made in order to advantageously solve this problem, and is a half-thread type spark plug with a threaded portion only on the tip side of the main metal fitting, and prevents the gas get from falling off due to this. The purpose of the present invention is to provide a long reach flat sheet type spark plug that has a time release effect.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to embodiments shown in all drawings.

FIG. 2 is a longitudinal cross-sectional view of a main part of a spark plug according to an embodiment of the present invention, showing how it is mounted on a cylinder head. Note that parts common to the conventional spark plug (Fig. 1) are designated by the same reference numerals.

Reference numeral 1 denotes a metal shell, in which a main body 7 and a body part 8 equipped with mounting screws for the cylinder head 6 are connected via a crotch-like flat sheet 9, and a center electrode 2 is installed in the inner cavity of the metal shell 1 according to known specifications. A porcelain insulator is sealed and fixed. Reference numeral 4 designates a ground electrode welded to the end face of the metal shell l, and reference numeral 5 designates a sealing gasket which is interposed between the upper surface of the cylinder head 6 and the flat sheet 9 and is made of a generally used plate material.

In the present invention, the male screw 1a for mounting is threaded on the tip portion of the 1riI body 8 of the metal shell 1, which corresponds to one half of the body close to the combustion chamber 10, and this portion is approximately - approximately - of the reach L of the body overall length. over. The thread diameter A of the mounting screw part is io, 12
t141! Various legs of Iz, reach L is about 19ff. The remaining body portion of the threaded portion 1a is provided with a non-threaded portion 1b, which is formed into a columnar shape with a diameter B equal to or larger than the thread diameter A, and is connected to the flat sheet 9 through an R portion 1ci. A concave portion 1d having an annular groove is formed between the base of the non-threaded portion 1b and the flat sheet 9;
In order to support the gasket 5 in the recess 1d and prevent it from falling off, the dimensions of the recess 1d are equal to the unthreaded portion diameter Bj.
V is also formed to have a slightly smaller diameter C (diameter difference of about 0.05 to 0.5 mm), and gaskets are fixed in advance on the four parts. That is, as shown in FIG. 3, the gas get 5 is inserted from the tip of the metal shell 1, passes through the unthreaded portion 1b, and fits into the recess 1d, and also suppresses (temporarily compresses) the gasket l-i. The inner diameter bent portion 5ai of the gasket 5 is made to protrude inward and is engaged and fixed to the seat surface 1e of the recessed portion 1d. As shown in FIG. 4, as a means for preventing the gasket from falling off, when the gasket 15 is similarly inserted and the upper inclined inner end 15ai of the gasket is depressed, it protrudes inwardly and prevents the metal shell from falling off.
This can also be achieved by fixing it to the four parts 1d. Note that the structure of the gasket used in the present invention is not limited to the embodiments, and it is also possible to form a known protrusion on the inside of the gas get to serve as a suppressor in order to improve the de-aging effect. The point is that the gasket may be fixed in advance to the four parts 1d of the metal shell 1 so as not to fall off.

To describe the specific dimensions of the present invention, for example, the thread diameter AklOπm of the metal shell 1, the diameter B of the non-threaded portion 1b is 12, the inner diameter of the gasket 5 is 12ffff, and the recess 1d of the metal shell 1 is fully inserted. Press it to an outer diameter of 11.85 mm to fix the gas in the recess 1d. This spark plug has a gap between the 10g internal thread 6a of the cylinder head 6 and the non-threaded portion 1b of the metal shell 1 by approximately 0.2 to 1.
It is screwed onto the cylinder head 6 having a fitting hole 6b with a gap of 0πU. In this way, in the present invention, by setting the diameter of the unthreaded portion 1b of the metal shell 1 to be equal to or larger than the outer diameter of the screw, the strength of the metal shell is increased, and because of this dimension, the gas get does not fall off. Easily attaches the plug to the cylinder head.

As described above, the long reach flat sheet type spark plug of the present invention has a threaded portion of any type such as U1O++2+14D screwed on the tip side of the main metal fitting to be screwed into the cylinder head. An unthreaded body part is provided on the next base side with a diameter equal to or larger than the thread diameter, and is loosely fitted between the cylinder head and the unthreaded part between the unthreaded part and the flat sheet. A recess with a diameter slightly smaller than the outer diameter is provided, and the gasket is fixed in the recess to prevent it from falling off, increasing the strength of the metal shell when installing the spark bladder and preventing leakage between it and the insulator. This can be effectively prevented and the production of insulators can be facilitated. The half-threaded type not only makes it easier to attach and detach the bladder, but also has the effect of removing the gasket, so the gasket can maintain its tightness without falling off even when the plug is attached and detached several times. can.

In particular, spark plugs with a small thread diameter of 10ππ and a long reach of 19 mm can be advantageously developed without impairing performance. Furthermore, since the clearance between the cylinder head and the metal shell can be uniformly reduced, there is a thermally advantageous effect.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part showing how the cylinder head of a conventional spark plug is installed, Fig. 2 is a cross-sectional view of the main part 1 and a half showing how the cylinder head of the spark plug of the present invention is installed. FIG. 2 is a cross-sectional view of the main part 1 and a half showing how the gasket is fitted in the spark plug, and FIG. 4 is a sectional view of the main part 1 showing how the gasket is fitted in another embodiment of the present invention.
It is a sectional view of half. 1... Metal shell 1a... Threaded part 1b... Unthreaded part 1d... Recessed part 5... Gasket 6...
・Cylinder head 7...Main body 8...Body part 9
...flat sea 2

Claims (1)

[Claims] (1) A body 7 with a relatively large diameter has a body part 8 equipped with a mounting screw for the cylinder head and a flat seat 9 in the shape of a crotch seat.
In a spark plug equipped with a metal shell connected through a metal shell, one half of the body 8 following the flat sheet 9 is formed as a threadless part 1b, and the remaining other end part is formed as a threaded part 1a for attaching to the cylinder head. Unthreaded part 1b
is attached to the cylinder head with an outer diameter at least larger than the outer diameter of the mounting threaded part la, and the threadless part 1 is installed between the flat sheet 9 and the threadless part 1b.
Did you provide a strange recess 1d' that is slightly smaller than the outer diameter of b, and install a gas get in advance in this recess to prevent it from falling out? [4] Long reach flat sheet type spark plug.