Glow plug

Claim 2

In a glow plug ignitor of the type used in small two-cycle internal combustion engines, having a hollow cylindrical casing and a central pin-terminal, the improvement comprising a substantially flat-spiral-coiled, flexible resistance element one end of which is electrically connected to said casing and the other to said pin-terminal, said element being oriented substantially perpendicularly to the axis of said pin-terminal and being normally substantially free of support between the said pin-terminal and said casing, a glass seal, fused to an interior wall of said hollow casing and to said pin-terminal and having a surface immediately behind said resistance element, closely adjacent said element but spaced therefrom through at least a major portion of the radial extent of said element, the spiral reaches of said element between the two ends thereof being radially inboard of said casing.

Claim 3

The improvement of claim 1 wherein the said glass seal is taken from the class consisting of vitreous and partially crystallized glass.

Claim 4

The improvement of claim 1 wherein a second seal is provided, spaced from said first seal in a direction away from said resistance element, said first and second seals constituting the sole means for mounting said pin in said body.

Claim 5

In a glow plug ignitor of the type used in a small two-cycle internal combustion engine, having a cylindrical casing and a central pin-terminal, said casing having a passage extending axially through it and a nose section intended to communicate with a cylinder of said engine, the improvement comprising an electrically insulating seal bonded to a passage defining wall of said casing and to said pin-terminal, electrically insulating said pin from said casing and hermetically closing the passage in said casing, and a surface of heat and corrosion resistant material, recessed within said passage slightly as compared with the total length of the passage, from the outboard end of said nose section; and a substantially flat-spiral-coiled, flexible resistance element one end of which is electrically connected to said pin-terminal and the other end of which is electrically connected to said casing, said element being oriented substantially perpendicularly to the axis of said pin-terminal and being normally closely adjacent said surface but spaced therefrom through at least a major portion of the radial extent of said element, the spiral reaches of said element between the two ends thereof being radially inboard of the passage-defining surface of said casing at the outboard end of said nose section.

Claim 6

In a glow plug ignitor of the type used in a small two-cycle internal combustion engine, having a cylindrical casing and a central pin-terminal, said casing having a passage extending axially through it and a nose section intended to communicate with a cylinder of said engine, the improvement comprising an electrically insulating seal bonded to a passage defining wall of said casing and to said pin-terminal, electrically insulating said pin from said casing and hermetically closing the passage in said casing, and a surface of heat and corrosion resistant material, recessed within said passage slightly as compared with the total length of the passage, from the outboard end of said nose section; and a substantially flat-spiral-coiled, flexible resistance element one end of which is electrically connected to said pin-terminal and the other end of which is electrically connected to said casing, said element being oriented substantially perpendicularly to the axis of said pin-terminal and being normally closely adjacent said surface but spaced therefrom through at least a major portion of the radial extent of said element, the spiral reaches of said element between the two ends thereof being radially inboard of the passage-defining surface of said casing at the outboard end of said nose section.

Claim 7

The improvement of claim 4 wherein the said surface is dished concavely in an annulus between the casing and the pin terminal.

Claim 8

The improvement of claim 4 wherein the said surface constitutes a part of the said seal.

Claim 9

The improvement of claim 6 wherein the seal is unitary and extends through sustantially the full length of the passage.

Claim 10

The improvement of claim 4 wherein the surface constitutes a part of a seal different from said hermetic seal.

Claim 11

The improvement of claim 4 wherein a plurality of hermetic seals is provided, of one of which said surface constitutes a part.

Claim 12

The improvement of claim 9 wherein the said seals are of different compositions.

Claim 13

The improvement of claim 9 wherein the seals are spaced from one another.

Claim 14

The improvement of claim 4 wherein the said surface of heat and corrosion resistant material is of a composition different from said hermetic seal.