Electric heating – Heating devices – Resistive element: igniter type
Reexamination Certificate
2000-02-15
2001-08-21
Jeffery, John A. (Department: 3742)
Electric heating
Heating devices
Resistive element: igniter type
C123S14500A, C029S611000, C029S613000, C219S544000, C219S546000
Reexamination Certificate
active
06278088
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention is directed to a rod glow plug with a glow tube.
2. Description of the Prior Art
[0002] Rod glow plugs are generally known and have a glow tube in which there are heating coil(s) and optionally control coil(s) series connected to one another, the coils in the terminal-side area being connected to one terminal pole and in the glow tube tip being connected to the glow tube. Conventionally, the coils are embedded within the glow tube in an electrically insulating conductive material. In the area of the glow tube tip it first of all has an opening in which the coil end on the side of the combustion space is welded to the glow tube with the formation of a welding spot. This welding spot causes a heavy accumulation of material which adversely affects the preheating time of the plug. The high welding energy which must be applied for welding of the glow tube and the heating coil is likewise disadvantageous. Especially for long rod glow plugs and/or for heating coils with thin wires, centering of the heating coil in the area of the welding spot represents a major problem, the rod glow plugs often being faulty when the heating coil is not exactly centered.
SUMMARY OF THE INVENTION
[0003] An object of the invention is to overcome the indicated defects in the prior art and to make available a rod glow plug with a coil which is centered very accurately, and scrap due to poor centering of the coil being greatly reduced in its production.
[0004] These and other objects are achieved in accordance with the present invention by providing rod glow plug with a glow tube, inner heating coil(s) and optionally control coil(s), and a terminal pole which leads into the glow tube, the coil(s) being connected to the terminal pole and the glow tube tip, characterized in that there is a stabilizer rod which extends in an assembly stage from the terminal pole to the glow tube tip, optionally into an opening in the glow tube tip or through it, and the stabilizer rod being located essentially in the middle running through the coil(s).
[0005] By welding the glow tip to the heating coil with the stabilizer rod in accordance with the present invention, the rod glow plug in accordance with the present invention has less material accumulation than in conventional welding; in addition, the new stabilizer rod of the rod glow plug in accordance with the present invention enables small-space, localized welding techniques, as for example, laser welding. Thus, when welding the heating coil of the rod glow plug in accordance with the present invention with the stabilizer rod, more accurate resistance values arise than in conventional welding with resulting undefined welding spot.
[0006] In the installation of the rod glow plug in accordance with the present invention with a stabilizer rod, the heating coil is advantageously held still and accurately centered; the fracture site of the stabilizer rod provided in a special embodiment leads to its reliable separation in the sealing of the heating rod by for example swaging and thus to prevention of short circuits. In addition, the use of the stabilizer rod in the rod glow plug in accordance with the present invention leads to desirable uniform heat dissipation due to the lower material accumulation at the glow tube tip during welding and due to the exact centering of the heating coil in the glow tube.
REFERENCES:
patent: 4476378 (1984-10-01), Takizawa et al.
patent: 1 825 999 (1961-02-01), None
patent: 34 13 850 (1984-10-01), None
patent: 4036162 (1992-05-01), None
patent: 1 413 147 (1991-02-01), None
patent: 859659 (1961-01-01), None
patent: 927336 (1962-01-01), None
patent: 58-21 (1983-01-01), None
patent: 60-86327 (1985-05-01), None
Allgaier Martin
Eller Martin
Beru AG
Jeffery John A.
Nixon & Peabody LLP
Safran David S.
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