JPS58138923A - Two-wired type glow plug - Google Patents

Abstract

PURPOSE:To obtain a two-wired type glow plug which is easy to process and assemble, and can serve for production cost reduction, at the same time providing a positive sealing and electric insulation at a securing face between a fixture and a heating tube. CONSTITUTION:A heating tube 2 is inserted centrally into a fixture 1 and while establishing an alignment, an electric insulation ceramic pipe 5 is inserted into an annular clearance formed between an inner peripheral wall of the fixture 1 and an outer peripheral wall of the heating tube 2, the ceramic pipe 5 having a metallic layer deposited by baking a paste containing a compound of vitreous materials around inner and outer peripheral walls thereof, the vitreous materials being made of metallize or metallic paste and the like such as silver and copper. Soldering is made to an area between the outer peripheral wall of the sheath tube 21 and the inner peripheral wall of the ceramic pipe 5, and also an area between the outer peripheral wall of the ceramic pipe 5 and the inner peripheral wall of the fittings 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-wire glow plug in which both terminals are installed insulated from an engine.

A rod-shaped center electrode is inserted into a metal sheath tube with a closed tip, the tip of the center electrode and the bottom of the sheath tube are connected with a heating wire, and an insulating material is filled into the sheath tube to remove the center electrode. A two-wheeled glow plug has been manufactured in which a heating tube with a fixed heating wire is coaxially inserted into a hollow mounting bracket and fixed in an electrically insulated state. As shown in Figure 1,
A tapered portion 11 is formed at the tip of the mounting bracket 1, an outer WI 30 having a tapered portion corresponding to the tapered portion 11 on the heat generating tube 2 is FM viewed, and the outer cylinder 3 including the tapered portion is formed.
Insulation 1940 made of mica, ceramic, or glass coating is attached to the outer circumferential surface of 0 to insulate it from the mounting bracket 1, and the rear end of the mounting bracket is filled with ceramic powder 50 to connect the mounting bracket and the heat generating tube. Since the tapered surface of the outer cylinder 30 is pressed against the tapered surface of the mounting bracket 1, the mounting bracket 1 and the heat generating tube 2 are sealed.
However, the insulating layer 40 is likely to peel off, crack, or cause insulation defects, and the insulating layer 40 and the inner circumferential surface of the mounting bracket 1 are only in pressure contact and cannot be bonded. As a result, gas inside the engine easily reached the end surfaces of the ceramic powder, resulting in insufficient airtightness. Furthermore, there is a drawback that the number of parts is large, making assembly difficult and increasing costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a two-wire glow plug that can provide strong sealing and electrical insulation between the fitting surface of a mounting bracket and a heating tube, and can be easily processed and assembled to reduce manufacturing costs.

Next, the present invention will be explained based on FIGS. 2 and 3.

Reference numeral 1 indicates a cylindrical mounting bracket having a mounting screw 12 formed on the outer periphery for mounting the engine, and 2 indicates a heat-generating tube. A metal center electrode 22 is inserted into the center of a heat-resistant metal sheath tube 21 with a closed tip 21A. The center electrode 22 and the heat generating wire 23 are fixed within the sheath tube 21 by welding and connecting a heating wire 23 made of a spirally wound nichrome wire between its tip 22A and the bottom wall 21E of the sheath tube 21. For this purpose, an electrically insulating ceramic powder 24 of magnesia, alumina, or beryllia is filled under pressure, and a glass sheath 25 is provided at the end of the opening. The fitting between the mounting bracket 1 and the heat generating tube 2 is achieved by inserting the heat generating tube 2 through the center of the mounting bracket 1, and while aligning the fitting, inserting the heat generating tube 2 into the annular shape between the inner circumferential wall of the mounting bracket 1 and the outer circumferential wall of the heat generating tube 2. Metalizing the inner peripheral wall and outer peripheral wall in the gap 4, or
An electrically insulating ceramic pipe 5 on which a metallized layer is attached by adhering and baking a paste made of a glassy material such as a metal paste such as silver or copper with metal powder is inserted, and a sheath tube 2 is inserted.
The outer circumferential wall of the ceramic pipe 5 and the inner circumferential wall of the ceramic pipe 5 are brazed together, and the outer circumferential wall of the ceramic pipe 5 and the inner circumferential wall of the mounting bracket 1 are brazed together.

A two-wire glow plug brazing method of the present invention is illustrated.

A ceramic pipe 5 is fitted into the gap between the mounting bracket 1 and the sheath tube 2, and the receiver is placed on a jig A, and a brazing material 8 is placed on the fitting surface and heated to braze the fitting surface.

As described above, in the two-wheeled glow plug of the present invention, the heating tube, which has a heating wire arranged inside a metal sheath tube with a closed tip, is inserted coaxially into a hollow mounting bracket and is electrically connected. In a two-wheeled glow plug that is fixed in an insulated state, the fitting between the heat generating tube and the mounting bracket is such that an electrically insulating ceramic pipe having metallized zones formed on the inner and outer circumferential surfaces is connected to the outer circumference of the sheathed tube. Insert into the annular gap formed between the wall and the inner peripheral wall of the mounting bracket, and braze the fitting surface between the outer tail wall of the sheath tube and the inner peripheral wall of the ceramic pipe, and the fitting surface between the outer peripheral wall of the ceramic pipe and the inner peripheral wall of the mounting bracket. Since the heat-generating tube is made of a metal material, the sealing and electrical insulation of the fitting surface between the mounting bracket and the heat generating tube can be made strong, and processing and assembly are easy, thereby reducing manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional two-wire glow plug, Fig. 2 is a sectional view of a two-wire glow plug of the present invention, and Fig. 3 is a process diagram for brazing the two-wire glow plug of the present invention. It is. 1...Mounting bracket, 2...Heating tube, 5...Ceramic vibe Figure 1 t! λ21 (1 21A , + , a7';! Procedural amendment tooth ζ month 1972 [] Director General of the Patent Office 1, Indication of the case Patent Application No. 21692 of 1982
, Name of the invention Two-wire glow plug 3, Person making the amendment Y
NGK Spark Plug Co., Ltd. (454) Representative: Shuho Ogawa 4, Agent: 465 Phone: 052-773-24496,
Detailed description of the invention in the specification to be amended. 7. Contents of the amendment As shown in the attached sheet. Attachment 1, Detailed Description of the Invention Column (1) Page 2, Line 10, [Manufactured] is changed to "It is manufactured with a jaw structure (for example, see Japanese Utility Model Publication No. 45-4089)." do.

Claims (1)

[Scope of Claims] 1) A heating tube consisting of a heating wire arranged inside a metal sheath tube with a closed tip is coaxially inserted into a hollow mounting bracket and is electrically insulated. In the fixed two-wire glow plug, the heat generating tube and the mounting fitting are fitted by connecting an electrically insulating ceramic pipe with metallized layers formed on the inner and outer circumferential surfaces to the outer circumferential wall of the sheath tube. It is inserted into the annular gap formed between the inner circumferential wall of the mounting bracket and the fitting surface between the outer circumferential wall of the sheath tube and the inner circumferential wall of the ceramic pipe, and the fitting surface between the outer circumferential wall of the ceramic pipe and the inner circumferential wall of the mounting bracket are brazed. A two-wire glow plug featuring: