Metal sheath glow plug
AssigneeFederal-Mogul Ignition Company
InventorsCamillo Rena, Sandro Goretti, Marcello Cino, Laura Beretta
Life of this patent
Estimating the term…
Abstract
A glow plug (10) which includes an annular metal shell (12), thermally conductive tubular sheath (20), electrode (22), resistance heating element (24), and electrically insulating, thermally conductive powder (26). A metallic seal (28) is disposed in an open end of the sheath (20) in sealing engagement with the electrode (22). An insulating layer (54) is formed on the outer surface of the electrode (22) so as to prevent electrical conductivity between the metal seal (28) and the electrode (22). An optional secondary metal layer (56) may be disposed between the insulating layer (54) and the metal seal (28).
Claims26
A glow plug, comprising:
- a metal shell having an axially extending bore;
- an electrically and thermally conductive tubular sheath having an open end disposed within said bore in electrical contact with said shell and a closed end projecting from said bore;
- an electrode having an embedded section extending into said open end of said sheath, said embedded section having a discrete insulating layer thereon;
- a resistance heating element disposed in said sheath having a proximal end which is electrically connected to said embedded section of said electrode and a distal end electrically connected to said closed end of said sheath;
- an electrically insulating, thermally conductive powder disposed within said sheath and surrounding said embedded end of said electrode and said resistance heating element;
- and
- a metal seal disposed in said open end of said sheath in sealing engagement with said sheath and said insulating layer of said electrode.
A glow plug, comprising:
- a metal shell having an axially extending bore;
- an electrically and thermally conductive tubular sheath having an open end disposed within said bore in electrical contact with said shell and a closed and projecting from said bore;
- an electrode having an embedded section extending into said open end of said sheath, said embedded section having a discrete insulating layer thereon;
- a resistance heating element disposed in said sheath having a proximal end which is electrically connected to said embedded section of said electrode and a distal end electrically connected to said closed end of said sheath;
- an electrically insulating, thermally conductive powder disposed within said sheath and surrounding said embedded end of said electrode and said resistance heating element;
- a metal seal disposed in said open end of said sheath in sealing engagement with said sheath and said insulating layer of said electrode;
- and
- a secondary metal layer disposed on said insulating layer, wherein said metal seal is in sealing engagement between said sheath and said secondary metal layer.
A method of making a heater assembly for a glow plug which includes an electrically and thermally conductive tubular sheath having an open end and a closed end;
- an electrode having an embedded section extending into the open end of the sheath, the embedded section having an insulating layer thereon;
- an electrically insulating, thermally conductive powder disposed within the sheath and surrounding the resistance heating element;
- and a metal seal disposed in the open end of the sheath in sealing engagement between the sheath and the insulating layer;
- said method comprising the steps of:
- forming a tubular sheath, electrode and resistance heating element;
- forming an insulating layer on at least a portion of the embedded section of the electrode;
- attaching one end of the resistance heating element to the embedded section of the electrode;
- inserting the resistance heating element and the embedded section of the electrode into the tubular sheath;
- attaching another end of the resistance heating element to the closed end of the sheath;
- inserting the powder into the sheath around the resistance heating element;
- and
- forming the metal seal between the sheath and the insulating layer.
Dependencies are inferred from the claim text.