GB2185529A - Sparkplug - Google Patents

Abstract

The sparkplug for an internal combustion engine has a heating coil 14 wound around the insulating body 11 inside the casing 10. Passage of electrical current through the coil 14 warms the sparking electrodes 21, 30 and helps to evaporate any fuel which has condensed thereon. Starting of the engine is facilitated. <IMAGE>

Description

SPECIFICATION Sparkplug This invention relatesto a sparkplug.

Sparkplugs are well known and comprise an electrically conducting externally screw-threaded casing with an annular electrically insulating body passing throug hthe casing. Aconducting member passes through the annular body, and has a portion projecting at one end so as to be in close proximity to a tongue extending from the casing, a spark gap being defined between the tongue and said portion which define terminals.

The conducting member and the casing are connected, in use, to a high voltage electrical supply which causes sparking across the gap.

Sparkplugs do not spark iffuel condenses on the terminals and, when this occurs, the engine is usually leftfor a period oftime until the fuel has evaporated, or the sparkplugs are removed, dried and re-installed.

The present invention provides a sparkplug which alleviates this problem.

One aspect of the invention provides a sparkplug comprising an electrically insulating body, carried in an electrically conducting casing, and an electrically operable heating means adapted to heat at least one of the sparking terminals of the sparkplug.

Preferably, the heating means is accommodated between the body and the casing.

Preferably the heating means is in the form ofan electrical heating element coiled around the insulating body and electrically insulated from the surrounding casing.

Preferably, the casing serves as one electrical terminalforthe heating meansandanotherterminal is mounted on the casing and electrically insulated from it.

The invention may also reside in an assembly of a plurality of sparkplugs as defined above, electrical conductors for connection between an electrical power source and the sparkplugs for operating the heating means and an on/off switch.

Reference is made to the accompanying drawings, wherein Figure 1 shows in diagrammaticform a sparkplug accordingtothe invention; Figure2 shows a diagrammatic sectional view of the sparkplug of Figure 1; Figure 3 shows a heating element which is incorporated in the sparkplug; and Figure 4shows how sparkplugs according to the invention may be connected to an electrical power source.

The sparkplug shown in Figures 1 and 2 comprises an electrically conducting externally screw-threaded casing 10, having a hexagonalformationiSfor engagementwith a spanner and an adjacent externally screw-threaded section 16 for engaging in an enginecylinder block. Acrankedtongue 21 projects from a terminal end 26 of the casing 10.

An insulating body 11 is housed in the external casing 10 and a conducting member 12 extends through the insulating body 11, and projects from each end thereof, one end portion 30 being in close proximitytothetongue21.Asparkgap 17 is defined between the tongue 21 and the portion 30 which define terminals.

An annularchamber31 is provided adjacentthe terminal end ofthe casing and is defined between an insulating layer32insidethecasing 10 and the insulating body 11. A heating element 14 is helically coiled around the insulating body 11 in the chamber 31 and connects at one end via an insulated conductor 18 to an electrical tag 13 which is mounted on the outside of the casing 10. The tag is electrically insulated from the casing. The other end of the heating element 14 is electrically connected to the casing 10.

Figure 4 shows sparkplugs as mounted in a cylinder blockfor use and illustrates howthe electrical connections to the heating elements may be made. The electrical power source is a vehicle battery whose negative terminal 40 is connected with the vehicle body and hence with the casings 10 ofthe sparkplugs. The positive terminal 41 is connected by insulated wiring with the tags 13 through an on/off switch 23.

In an alternative embodiment the heating element is embedded in an electrically insulating medium, which may take the place of the insulating layer 32 in the casing.

In use,tofacilitatestartingoftheengineincold weather the on/off switch may be operated to heat the sparkplugs and vapourise any fuel which may have condensed on the sparkplugs.

A heating element corresponding to element 14 may be located at any convenient location in or on the sparkplug and in any convenient configuration, provided that at least one of the sparking terminals, but preferably both, is warmed when the heating element is operated.

1. A sparkplug comprising an electrically insulating body, carried in an electrically conducting casing, and an electrically operable heating means adapted to heat at least one ofthe sparking terminals ofthe sparkplug.

2. A sparkplug according to Claim 1 wherein the heating means is accommodated between the body and the casing.

3. Asparkplug according to Claim 2 wherein the heating means comprises an electrical resistance heating element coiled around the body and electrically insulated from the casing.

4. Asparkplug according to any one ofthe preceding claims wherein the casing is adapted to serve as one electrical terminal for the heating means, and a second terminal is provided which is electrically insulated from the casing.

5. A sparkplug according to Claim 4wherein the second terminal is mounted on the casing.

6. An assembly of a plurality ofsparkplugs according to any one ofthe preceding claims, electrical conductors for connection between an electrical power source and the sparkplugs-for operating the heating means, and an on/off switch.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sparkplug This invention relatesto a sparkplug. Sparkplugs are well known and comprise an electrically conducting externally screw-threaded casing with an annular electrically insulating body passing throug hthe casing. Aconducting member passes through the annular body, and has a portion projecting at one end so as to be in close proximity to a tongue extending from the casing, a spark gap being defined between the tongue and said portion which define terminals. The conducting member and the casing are connected, in use, to a high voltage electrical supply which causes sparking across the gap. Sparkplugs do not spark iffuel condenses on the terminals and, when this occurs, the engine is usually leftfor a period oftime until the fuel has evaporated, or the sparkplugs are removed, dried and re-installed. The present invention provides a sparkplug which alleviates this problem. One aspect of the invention provides a sparkplug comprising an electrically insulating body, carried in an electrically conducting casing, and an electrically operable heating means adapted to heat at least one of the sparking terminals of the sparkplug. Preferably, the heating means is accommodated between the body and the casing. Preferably the heating means is in the form ofan electrical heating element coiled around the insulating body and electrically insulated from the surrounding casing. Preferably, the casing serves as one electrical terminalforthe heating meansandanotherterminal is mounted on the casing and electrically insulated from it. The invention may also reside in an assembly of a plurality of sparkplugs as defined above, electrical conductors for connection between an electrical power source and the sparkplugs for operating the heating means and an on/off switch. Reference is made to the accompanying drawings, wherein Figure 1 shows in diagrammaticform a sparkplug accordingtothe invention; Figure2 shows a diagrammatic sectional view of the sparkplug of Figure 1; Figure 3 shows a heating element which is incorporated in the sparkplug; and Figure 4shows how sparkplugs according to the invention may be connected to an electrical power source. The sparkplug shown in Figures 1 and 2 comprises an electrically conducting externally screw-threaded casing 10, having a hexagonalformationiSfor engagementwith a spanner and an adjacent externally screw-threaded section 16 for engaging in an enginecylinder block. Acrankedtongue 21 projects from a terminal end 26 of the casing 10. An insulating body 11 is housed in the external casing 10 and a conducting member 12 extends through the insulating body 11, and projects from each end thereof, one end portion 30 being in close proximitytothetongue21.Asparkgap 17 is defined between the tongue 21 and the portion 30 which define terminals. An annularchamber31 is provided adjacentthe terminal end ofthe casing and is defined between an insulating layer32insidethecasing 10 and the insulating body 11. A heating element 14 is helically coiled around the insulating body 11 in the chamber 31 and connects at one end via an insulated conductor 18 to an electrical tag 13 which is mounted on the outside of the casing 10. The tag is electrically insulated from the casing. The other end of the heating element 14 is electrically connected to the casing 10. Figure 4 shows sparkplugs as mounted in a cylinder blockfor use and illustrates howthe electrical connections to the heating elements may be made. The electrical power source is a vehicle battery whose negative terminal 40 is connected with the vehicle body and hence with the casings 10 ofthe sparkplugs. The positive terminal 41 is connected by insulated wiring with the tags 13 through an on/off switch 23. In an alternative embodiment the heating element is embedded in an electrically insulating medium, which may take the place of the insulating layer 32 in the casing. In use,tofacilitatestartingoftheengineincold weather the on/off switch may be operated to heat the sparkplugs and vapourise any fuel which may have condensed on the sparkplugs. A heating element corresponding to element 14 may be located at any convenient location in or on the sparkplug and in any convenient configuration, provided that at least one of the sparking terminals, but preferably both, is warmed when the heating element is operated. CLAIMS

1. A sparkplug comprising an electrically insulating body, carried in an electrically conducting casing, and an electrically operable heating means adapted to heat at least one ofthe sparking terminals ofthe sparkplug.

2. A sparkplug according to Claim 1 wherein the heating means is accommodated between the body and the casing.

3. Asparkplug according to Claim 2 wherein the heating means comprises an electrical resistance heating element coiled around the body and electrically insulated from the casing.

4. Asparkplug according to any one ofthe preceding claims wherein the casing is adapted to serve as one electrical terminal for the heating means, and a second terminal is provided which is electrically insulated from the casing.

5. A sparkplug according to Claim 4wherein the second terminal is mounted on the casing.

6. An assembly of a plurality ofsparkplugs according to any one ofthe preceding claims, electrical conductors for connection between an electrical power source and the sparkplugs-for operating the heating means, and an on/off switch.

7. Asparkplug according to Claim 1 and substantially as described herein with reference to and as shown in the accompanying drawings.