JPS6240618B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of welding and joining a glow tube in which a resistor is housed within a metal tube with a closed end through insulating powder, with the tip end protruding from the end surface of the shaft hole of a mounting fitting. .

Generally, silver brazing is often used to connect the glow tube used in sheathed glow plugs and the mounting hardware. However, although this brazed joint is satisfactory in terms of joint strength and airtightness,
Because it involves heating to 800℃, it is not possible to plate the mounting hardware in advance, so after brazing it is necessary to polish it and apply anti-corrosion treatment such as painting.In particular, the seal with the engine is conical. In the case of sheets, it is necessary to cut the flux or brazing material onto the sheet surface of the mounting bracket, which is also a factor in significantly increasing costs. Another known method is to mechanically connect the two by press-fitting or radial compression, but it has been difficult to maintain airtightness. Furthermore, the third
In the method of welding by arc welding in an inert gas, the welding time is relatively long, so the residual air in the filler powder in the glow tube expands rapidly and is injected into the welding area, causing the through hole. It was not possible to weld due to this. In particular, welding becomes increasingly difficult for rapid type glow plugs in which the glow tube has a thinner wall thickness to improve heat generation characteristics.

The present invention provides a method for welding a glow tube to a sheathed glow plug fitting that overcomes the above-mentioned problems by a rapid welding method. The present invention will be described below based on illustrated embodiments.

FIG. 1 shows a sheathed glow plug according to an embodiment of the present invention, and 1 is its glow tube. This glow tube includes, for example, an iron chrome tube wound in a coil shape inside a metal tube 2 made of stainless steel.
One end of a resistance material 3 such as a nickel wire is welded and closed at the tip of the tube 2, and the other end is joined to the center shaft 4, and is filled with an insulating powder 5 such as magnesia. Drawing processes such as swaging are applied to increase density. Reference numeral 6 denotes a mounting bracket with an engine mounting screw, and the groove tube is inserted into the shaft hole 6.
The end surface 6b of the shaft hole 6a of the mounting bracket is inserted into the shaft hole 6a of the mounting bracket.
A circumferential welded portion 7 is formed in the annular gap between the glow tube 1 and the glow tube 1 by plasma welding, electron beam welding, or laser welding.

Plasma, electron beam, and laser welding can be applied to welding thin materials such as glow tubes because microfabrication can be performed in an extremely short time. Among these, laser welding is the most preferred because it causes almost no mechanical or thermal distortion. Therefore, when welding using these welding methods, welding can be performed quickly, and the remaining air inside the glow tube is prevented from expanding, so that the seam portion can be completely welded without causing penetration failure of the tube.

In the figure, reference numeral 8 denotes an insulator made of resin or ceramic, which is inserted into the center shaft 4, locked onto the step of the mounting bracket, and fastened with a nut 9, which is a glow plug that maintains airtightness and electrical insulation of the center shaft. .

As mentioned above, since the glow tube can be quickly welded to the mounting bracket of the present invention using plasma welding, electron beam welding, or laser welding, penetration failure of the glow tube can be prevented and both can be completely welded. In particular, even when the glow tube is as thin as 0.5 mm, no penetration failure occurs, so the heat generation properties can be quickly achieved and the airtight joint strength can be sufficiently maintained. Further advantageously, the mounting bracket can be subjected to rust prevention treatment such as plating in advance, which has the effect of reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional side view showing a joined state of a mounting bracket and a glow tube according to an embodiment of the present invention. 1... Glow tube, 2... Metal tube, 3...
Resistor, 5... Insulating powder, 6... Mounting bracket, 6a... Shaft hole, 6b... End surface.

Claims (1)

[Claims] 1. In a method in which a glow tube in which a resistor is housed in a metal tube with a closed end and a resistor via insulating powder is inserted into a shaft hole of a mounting bracket and the tip side is protruded and welded, the end face of the shaft hole of the mounting bracket is A method for welding a glow tube to a sheath type glow plug mounting fitting, characterized in that the annular gap between the glow tube and the glow tube is welded by plasma welding, electron beam welding, or laser welding.