JPS58150284A - Ingition unit for engine - 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 relates to an ignition device for an engine.

In recent years, as engine exhaust gas countermeasures and fuel efficiency regulations have been addressed, the shape of engine combustion chambers has become more complex, and the mounting locations of spark plugs are also becoming more restricted.

Therefore, miniaturization of spark plugs has recently been considered. One way to achieve this miniaturization is to eliminate the mounting bracket for the spark plug.

In this way, (2), for example, U.S. Patent No. 2. ,．． There is one described in the specification of No. 543.961. This is a structure in which a threaded portion is provided around the outer periphery of the insulator, and the insulator is directly screwed and fixed into a screw hole in the cylinder head of the engine.

Although it is possible to reduce the size of conventional structures such as this by eliminating the mounting hardware, since the insulator is screwed into the screw hole of the cylinder head, if the insulator is removed frequently, the screws of the insulator may become damaged. This causes problems such as parts becoming worn or missing.

An object of the present invention is to provide an engine ignition device that solves these problems.

An embodiment according to the present invention is shown in FIG. 1, and an enlarged view of the vicinity of the spark portion is shown in FIG. 2, which will be explained below. 1 is a cylinder head made of iron or aluminum, in which a through hole 1b having a threaded portion 1a is partially bored. 2 is an insulator made of alumina porcelain, which has a screw hole 2a1 and an unthreaded hole 2b in the center, and an annular large diameter portion 2 on the outer periphery.
It has C. Reference numeral 3 denotes an annular tightening ring for screwing and fixing the insulator 2 to the cylinder through the through hole 1b of the rod 1, and is composed of a tightening part 3a and a threaded part 3b. In this embodiment, the threaded portion 3b has a nominal diameter of 6fi. 4 is a terminal made of iron, which is screwed and fixed into the screw hole 2a.

The tip 2d of the tip 2 of the insulator 2 is made semiconductive by injecting Cr, Ni, etc. by ion implantation, or by coating with a semiconductor such as SiC. The resistance value is set to 10Ω. 5 is a ring-shaped electrode made of a heat-resistant alloy such as Ni, and its discharge surface is coated with a noble metal (for example, Pt80wt%).
-1r20wt%) is bonded.

This electrode 5 is screwed onto the tip 2d of the insulator 2. 6
is a ring-shaped ground electrode made of a heat-resistant alloy such as Ni, and a noble metal made of the same material as the electrode 5 is bonded to its discharge surface. This ground electrode 6 is inserted and fitted into the through hole 1b of the cylinder head 1. Reference numeral 7 denotes a conductive thin wire made of a piano wire or a Ni alloy wire that electrically connects the semiconductor portion 2d and the terminal 3. This thin wire 7 is inserted into the semiconductor portion 2d (4) to maintain electrical continuity. Further, the electrical conductor path 8 is formed on the end face of the terminal 3 by baking a metal paste such as silver paste, so that the end face of the thin wire 7 and the end face of the terminal 3 are brought into direct contact.

In the above configuration, the operation will be explained next. The procedure for assembling the insulator 2 to the cylinder head 1 is as follows.

That is, the insulator 2 is inserted into the through hole 1b of the cylinder head 1, and the annular large diameter portion 2C of the insulator 2 is supported by the seat portion 1c of the through hole 1b of the cylinder head 1. After that, insulator 2
The annular nut 3 is inserted into the outer periphery of the insulator 2, and the threaded part 3b of the nut 3 is screwed into the threaded part 1a of the through hole 1b of the cylinder head 1. and fixes the insulator 2 in the through hole lb of the cylinder head 1.

By the way, in the above embodiment, the outermost diameter of the insulator 2 (the large annular diameter portion 2C) is 4 to 8M in terms of withstand voltage, and the outer diameter of the terminal 3 is 2 to 4M in terms of connection with the high voltage cord. (2) The electrode 5 has an outer diameter of 0.5 to 2 ms and a thickness of 0.5 to 1.5 tm in terms of spark consumption resistance, and the thin wire 7 has a thickness of 06 (5) 3 to 1.5 fi. Therefore, it is very small. Furthermore, in this embodiment, noble metal is bonded to the electrodes 5 and 6 to suppress their spark consumption in order to achieve maintenance-free operation, so there is no need to check their wear and tear.

Furthermore, in this embodiment, since the semiconductor portion 2d is provided at the tip of the insulator 2, there is also a noise prevention effect.

In this way, in order to achieve miniaturization, the spark discharge type in this embodiment is a creeping discharge type. By setting the dimensional relationships described below when using this creeping discharge type, sparks can fly at a relatively low voltage even if the discharge path is long.

That is, as shown in FIG. 2, if the thickness of the insulator between the thin wire 7 and the insulator 2 is X, the protrusion length of the insulator is Y, and the protrusion length of the electrode 5 is Z, then 1.5X≦Y≦3X 0.4N It was found that it is sufficient to satisfy the following relationships: ≦X≦1.2 seagull 0, 2 H≦Z≦0.4 dragon. If the relationship between X and Y is diagrammed and its optimal range is shown, it is the shaded area in Fig. 3 (6).

By satisfying these related dimensions, during the initial discharge (capacitive discharge), the discharge occurs at a low voltage by flying along the creeping surface of the insulator 2, and during the subsequent discharge (inductive discharge), it leaves the surface of the insulator 2. discharge. Therefore, the overall voltage is low and sparks fly,
Moreover, it has good ignitability.

The present invention is not limited to the above-described embodiments, and various modifications can be made as follows.

Although the fll terminal 3 and the center electrode 6 are fixed by screwing, they may also be bonded and fixed with a ceramic adhesive.

(2) Ground electrode 4. The entire center electrode 6 may be made of noble metal.

(3) The thin metal wire 7 may not be straight, but may be curved. In this case, a platinum mold is used and the platinum wire is fixed by firing shrinkage of the insulator 2.

(4) Of course, the semiconductor portion 2b may be a complete conductive path, and the thin metal wire 7 may be made of a resistive material to provide noise prevention characteristics.

(7) (5) The electrode 4 may be formed into a convex shape and fixed to the insulator 2 by screwing. Further, the electrode 5 may be fixed by shrink fitting.

(6) The electrode 6 is not provided in the through hole 1b, but is inserted into the cylinder.
It may be provided on the inner surface of the.

In short, according to the present invention, since the insulator is not provided with a threaded portion, the conventional problems can be solved. Furthermore, the present invention can further contribute to miniaturization of the insulator by employing thin metal wires.

[Brief explanation of drawings]

FIG. 1 is a partially broken sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing an enlarged main part of FIG. 1, and FIG. 3 is a characteristic diagram for explaining the operation of the present invention. ■...Cylinder head, la...threaded part, lb...
・Through hole, 2... Insulator, 3... Naso), 3b screw part. 4...terminal, 5,6...electrode, 7...metal thin wire. Representative Patent Attorney Takashi Okabe (8) >E

Claims (1)

[Claims] (11) An engine cylinder head having an insulator having an electrode at its tip, a through hole large enough to insert the insulator, and a threaded portion in the hole; The insulator is provided with an annular NAND having a threaded portion screwed into the threaded portion of the through hole and an electrode disposed inside the cylinder head, and the insulator is inserted into the through hole of the cylinder head, and the insulator is insulated. An engine ignition device in which the insulator is fixed to the cylinder head by inserting the NAND around the outer periphery of the insulator and screwing the NAND into the threaded part of the cylinder head. (2) Having an electrode at one end. An insulator having a terminal at the other end, a thin metal wire provided inside the insulator to electrically connect the electrode and the terminal, and a through hole large enough to allow the insulator to be inserted therein. An engine cylinder (1) comprising a head, an annular NAND having a threaded part that screws into the threaded part of the through hole of the cylinder head, and an electrode disposed inside the cylinder head, The insulator is inserted into the through hole of the cylinder head, the NAND is inserted around the outer periphery of the insulator, and the NAND is screwed into the threaded portion of the cylinder head, thereby attaching the insulator to the cylinder head. Engine ignition device fixed to the head.