Electric heating – Heating devices – Resistive element: igniter type
Patent
1998-07-01
2000-04-04
Jeffery, John A.
Electric heating
Heating devices
Resistive element: igniter type
123145A, 219548, 338247, F23Q 700
Patent
active
060464348
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND INFORMATION
The present invention relates to a sheathed-element glow plug for auto-igniting internal combustion engines. Known sheathed-element glow plugs generally consist of a sheath, a connection terminal for the glow current, a tube secured to the sheath, the tube being sealed at the end facing away from the sheath, and a wire-filament-shaped resistor element which is embedded in thermally conductive insulating powder. The resistor element is arranged in the part of the tube which functions as the glow pencil and which protrudes out of the sheath. Sheaths for the various commercially available sheathed-element glow plugs vary depending on the structural shape and type of construction of the engine into which the sheathed-element glow plug is to be installed. Sheaths also differ in their length, which determines the overall length of the sheathed-element glow plugs. Therefore, for manufacturing purposes, sheaths and connection terminals for contacting the heating element must be available in great variety and in varying lengths.
SUMMARY OF THE INVENTION
The sheathed-element glow plug of the present invention has the advantage that various overall lengths can be obtained by using varying intermediate pieces. There is therefore no need to manufacture sheaths of various lengths or to have terminals of various lengths available. In this context, the required product range for component parts necessary for assembling a sheathed-element glow plug is substantially diminished. Given the possibility of manufacturing in larger quantities in series, this leads to a cost reduction for the sheathed-element glow plugs. In this context, the sheath and the terminals can be manufactured in two parts which are always fabricated in the same manner irrespective of the ultimate length of the sheathed-element glow plug. The sheath and the terminals can be adapted to the desired overall length simply by means of the variable intermediate piece.
The individual components can be joined by welding, soldering, shrinking, or pressing. It is ultimately advantageous to furnish the end faces of the sections of the sheath and of the variable intermediate pieces with an offset at the diameter, permitting them to be securely fixed in position before being joined.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts the principle structure of a sheathed-element glow plug according to the prior art.
FIG. 2A depicts a sheathed-element glow plug arranged according to the present invention to have an intermediate piece for obtaining varying overall lengths.
FIG. 2B depicts an enlarged illustration of a portion of the sheathed-element glow plug of FIG. 2A.
FIG. 3 depicts the joining of the intermediate piece to the sheath.
FIG. 4 depicts a glow pencil having a variable connection contact.
The sheathed-element glow plug depicted in FIG. 1 is comprised of a sheath 11 having a thread 12 and a hexagonal part 13. Sheath 11 is traversed by an axial bore, a glow pencil 14 being secured at its one end in the combustion chamber-end of sheath 11. The other end 15 of glow pencil 14, protruding into the combustion chamber, is sealed. Glow pencil 14 is made of a temperature-resistant material. Contained inside the glow pencil are insulating ceramic powder 16 and a wire filament arrangement which functions as a heating element. Wire filament arrangement 17 includes a heating filament having constant resistance and a control coil having temperature-dependent resistance. The free-standing end of wire filament arrangement 17 is fastened to a connector element 18 which protrudes into glow pencil 14. The combustion chamber-end of wire filament arrangement 17 is electrically connected to sealed end 15 of glow pencil 14. Connector element 18 is secured in sheath 11 and, on the side of sheath 11 away from the combustion chamber, forms a threaded bolt 19, where the connection to the glow current is made. An insulating washer 20 prevents electrical contact from occurring between sheath 11 and terminal element 18.
Virtually all commercially available sh
REFERENCES:
patent: 2456080 (1948-12-01), Pe
patent: 2898571 (1959-08-01), Moule et al.
patent: 4477717 (1984-10-01), Walton
patent: 5059768 (1991-10-01), Hatanaka et al.
patent: 5798504 (1998-08-01), Schwarzkopf
Locher Johannes
Nissen Jorg-Chr.
Teschner Werner
Jeffery John A.
Robert & Bosch GmbH
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