JPH03165480A - Ignition plug for automobile - Google Patents

Abstract

PURPOSE: To form an ignition plug with a suitable material with conductivity and corrosion resistance by fitting a metal core for forming a grounded electrode to a metal main body by a method other than welding. CONSTITUTION: A metal core 16 is fit to the edge part 14 of a metal main body 2, facing a center electrode 4a and surrounds the electrode 4a. A finger 18 for forming a grounded electrode of an ignition plug 1 is integrally formed in the core 16. In order to fit the core 16, the edge part 14 of the main body 2 is heated to expand outward, and the core 16 is inserted into the main body 2. The edge part 14 is cooled, contracted inward, and the core 16 is fastened and trapped in the main body 2. The tip of the finger 18 is bent, so as to face the electrode 4a. By fitting the core 16 to the main body 2 by a method other than welding like this, an ignition plug is formed with a suitable material with a conductivity and a corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an automotive spark plug, and more specifically, a metal hollow body provided with an insulated center electrode connected to a high-voltage electricity supply; The present invention relates to an automotive spark plug comprising a ground electrode carried by a hollow body and cooperating with the insulated center electrode.

(Prior Art) In addition to being integrally formed with one end of a metal body, the grounding electrode of a conventionally known automotive spark plug is usually composed of a metal rod welded to one end of the metal body using an arc welding method. There are some. However, in the case of a spark plug having the latter configuration, welding causes a significant change in the thermal rating of the spark plug, so there is a problem in connecting by welding.

(Objective and Structure of the Invention) The present invention has been made to solve the above-mentioned problems, and provides an automobile spark plug in which a ground electrode is formed on a core fixed in a metal body. It is intended to.

According to the present invention, not only is welding not used to connect the core that constitutes the ground electrode and the metal body, but the core that constitutes the ground electrode is not suitable for welding due to its characteristics. It may be made of any suitable material that is electrically conductive and corrosion resistant. Further, the core may be formed to have a plurality of ground electrodes, and in this case, the plurality of ground electrodes may each have a different shape.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an automobile spark plug, which is composed of a hollow metal body 2, a center electrode wire 4 disposed in the metal body 1, and an insulator 6 made of, for example, a ceramic material. There is. One end of the center electrode wire 4 is exposed externally from the insulator 6 to form a center electrode 4atl, and
The other end 8 is the end of the insulator 6 on the opposite side of the metal body 2 and is exposed to the outside, and is connected to a high-voltage electricity supply source, which is generally constituted by an ignition coil of an automobile, in a conventionally known manner. It has become.

Similar to conventionally known spark plugs, a threaded portion lO is formed on the outer circumferential surface of metal body 2 in the vicinity of center electrode 4a, so spark plug l according to the present invention is also similar to conventionally known spark plugs. , which can be screwed onto the cylinder head of an automobile engine. When screwing the spark plug 1 into the cylinder head, it is normal to use a wrench or spanner to screw the spark plug l, and for this purpose, the hexagonal outer periphery that engages with such a tool is 12 is formed on the metal body 2 on the side opposite to the threaded portion IO.

Reference numeral 16 denotes a metal core, the detailed structure of which is shown in FIGS. 3 and 4. As shown in the figure, the metal core 16 is fitted onto the end portion 14 of the metal main body 2 facing the center electrode 4al in a manner described later, and surrounds the center electrode 4a. Three fingers 18 constituting the ground electrode of the spark plug l are integrally formed on this metal core 16 and are spaced apart every 120 degrees in the circumferential direction, as shown in FIG. There is. At the same time, the tip of each finger 18
As clearly shown in the figure, it is bent so as to face the center electrode 4a substantially along the radial direction. After that, bend and form.

As shown in FIGS. 1, 2, and 6, the metal body 2
An annular protrusion 20 having a trapezoidal cross section is formed on the cylindrical inner wall surface 22 of. Both side surfaces of the annular protrusion 20 corresponding to the inclined sides of the trapezoid are inclined at a predetermined angle B with respect to the radius line A perpendicular to the longitudinal axis of the metal body 2, and the predetermined angle B is Within the range of 15 degrees to 45 degrees, preferably approximately 3
It is desirable to set it to 0 degrees. In addition, both side surfaces of the annular protrusion 20 are shown as a first inclined abutting surface 26 and a second inclined abutting surface 30, respectively, in FIG.

To fit the metal core 16, the end portion 14 of the metal main body 2 is heated to expand outward in the radial direction.

As the heating means at this time, it is desirable to use, for example, induction heating. In this manner, the end portion 14 of the metal body 2 is heated and expanded, and the metal core 16 is inserted into the metal body 12. When the end portion 14 of the metal body 2 is then heated and cooled, the end portion 14 contracts radially inward, so that the metal core 16 is tightly fitted inside the metal body 2. It turns out. At that time, the annular end 24 of the metal core 16 facing the opposite side from the fingers 18 constituting the ground electrode is pressed against the first inclined abutting surface 26 of the annular protrusion 20 on the inner wall surface 22 of the metal main body 2. and press it with a punch. In addition, the metal core 16 has a Fuuki annular protrusion 2.
A chamfered portion 28 is formed which abuts on the second inclined abutting surface 30 of the second inclined abutting surface 30, and this chamfered portion 28 comes to abut on the second inclined abutting surface 30 at that time.

An inclined stepped portion 32 is formed at the end of the insulator 6 surrounding the center electrode wire 4 on the center electrode 4a side. When the seven-flange end 34 of the metal main body 2 is later fitted into the insulator 6 by caulking, it comes into contact with the annular end 24 of the metal core 16 substantially along the longitudinal direction. The contact between the annular end portion 24 of the metal core 16 and the inclined step portion 32 of the insulator 6 forms an airtight zone that completely cuts off communication between the engine combustion chamber and the outside. Therefore, due to the existence of this airtight zone, there is no need to use a seal ring, which was conventionally necessary, between the insulator and the metal body.

Although FIG. 5 shows another embodiment of the present invention, the same reference numerals are used for the same components as used in the previous embodiments. However, in the embodiment shown in FIG. 5, the metal core 16 has only one finger 18 constituting the ground electrode, and moreover, there is only one finger 18 that is located opposite the center electrode 4a along the longitudinal axis of the insulator 6. It differs from the previous embodiment in that it is bent so as to Also in this embodiment, the bent tip of the finger 18 is formed by bending after the metal core 16 is fitted into the metal main body 2.

(Advantages) According to the present invention, as mentioned above, due to the existence of the airtight zone, there is no need to use a seal ring, and since the metal core 16 is used, the number of ground electrodes can be reduced. If it is easy to make the desired number of wires, and if the material is conductive and corrosion resistant, it can be constructed using that material even if it is not suitable for welding. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a spark plug according to the present invention, FIG. 2 is an enlarged vertical cross-sectional view of main parts of a spark plug according to the present invention, and FIG.
The figure is an enlarged view of the part indicated by arrow I11 in FIG.
4 is a cross-sectional view of FIG. 3, FIG. 5 is a longitudinal sectional view of a spark plug according to another embodiment of the present invention, and FIG. 6 is an enlarged sectional view of the portion indicated by arrow Vl in FIG. 1. It is.

Claims (1)

[Scope of Claims] 1) An automotive spark plug comprising a hollow metal body insulatingly supporting a center electrode member connected to a high-voltage electricity supply source, and a ground electrode member cooperating with the center electrode member, wherein the A spark plug for an automobile, characterized in that the electrode member is constituted by a core fixed to the metal hollow body. 2) The device according to claim 1, wherein the core is inserted into the metal hollow body and is fitted so as to surround the end of the center electrode member. Automotive spark plugs. 3) The device according to any one of claims 1 and 2, wherein an annular protrusion is formed on the inner wall surface of the metal hollow body, and the annular protrusion includes a ring of the core. A spark plug for an automobile, characterized in that it has a first contact surface with which an inner end comes into airtight contact. 4) The center electrode wire according to claim 3, wherein the center electrode wire is covered with an insulator, and the inner end of the insulator is provided with a wire extending approximately along the longitudinal direction and abutting against the inner end of the core. A spark plug for an automobile, characterized in that a slanted stepped portion is formed so that the two face each other and come into contact with each other, thereby creating an airtight zone. 5) The device according to any one of claims 3 and 4, wherein a chamfer is formed on the outer peripheral surface of the core, and the chamfer is on a side opposite to the first contact surface. A spark plug for an automobile, characterized in that the spark plug is in contact with a second contact surface of the annular protrusion. 6) The annular protrusion according to any one of claims 3 to 5, wherein the annular protrusion has a trapezoidal cross-sectional shape, and the annular protrusion has a cross section on both sides of the annular protrusion corresponding to the inclined sides of the trapezoid. A spark plug for an automobile, characterized in that first and second contact surfaces are formed that are inclined in opposite directions. 7) The device according to claim 6, wherein the first and second contact surfaces of the annular protrusion are inclined at a predetermined angle with respect to a radial line perpendicular to the longitudinal axis of the spark plug. A spark plug for an automobile, wherein the predetermined angle is within a range of 15 degrees to 45 degrees. 8) The device according to claim 7, wherein the predetermined angle is 3
An automobile spark plug characterized by being set at 0 degrees. 9) The device according to any one of claims 1 to 8, wherein the core has three fingers separated from each other by 120 degrees, and the fingers constitute a ground electrode. An automotive spark plug characterized by: