AU720740B3 - Improved gas igniter - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990

ORIGINAL

COMPLETE SPECIFICATION PETTY PATENT Invention Title: IMPROVED GAS IGNITER Name of Applicant: UTILUX PTY LIMITED The following statement is a full description of this invention, including the best method of performing it known to me/us: D1634/DI635 Skeletal Igniter -2- Improved Gas Igniter The present invention relates to a gas igniter, particularly, but not exclusively, to a gas igniter for igniting gas flames in appliances such as ovens, water heaters, boilers, and the like.

Conventional gas igniters comprise an electrode to which a voltage can be applied, to cause a discharge across a gap between the electrode and another conductive element (usually a part of the appliance), to ignite flammable fluid, such as natural gas. Such igniters are used in appliances such as domestic and commercial cookers, for lighting gas elements, boilers, water heaters and other appliances that utilise flammable fluid which requires ignition.

One known igniter comprises a flat topped electrode having a cylindrical body portion which is crimped or soldered to a conductive wire. The flat topped portion of the electrode provides a discharge surface. The cylindrical portion of the electrode and the conductive wire are seated within an insulated'housing. It is important that the electrical discharge takes place between the top portion of the electrode and the conductive part of the appliance. Problems occur when there is a defect in the insulation about the cylindrical part of that electrode and tracking may occur which can result in a defective igniter. In order to prevent or reduce the chances of tracking the conductive wire and the electrode may be covered by an insulating layer apart from the insulating housing, and also in order to insure that the electrode does not move out of the housing the assembly will be glued together. The gas igniter assembly of insulating housing, insulation, electrode and conductive wire is also mounted in a resilient mounting member to allow movement of the assembly during expansion and contraction due to temperature change. The conductive wire passes through the '2member and further insulation is provided to insulate the J:\Speci\300 399\300 349\32397.doc 3 conductive wire as it passes out of the member.

The insulating housings used are usually. ceramic insulators.

The entire assembly is quite complex and relatively laborious to assemble.

The present invention provides a gas igniter assembly comprising: a core body having an electrode discharge portion at one end of the core body, the electrode discharge portion being arranged to provide a discharge surface, a rigid distal portion remote from the discharge portion, and a rigid central portion connecting the discharge and distal portions; electrical insulation provided about the core body; and a mounting member including a passageway for receiving the rigid distal portion to mount the core body, the mounting member being constructed of a resiliently flexible material which grips the distal portion and thus holds the gas igniter assembly together.

Preferably, the rigid portion of the core body is provided with alocating means for locating the rigid distal end in position within the passageway in the mounting member. In a preferred embodiment, the locating means comprises a projection or barb which seats within the passageway within the mounting member and resists removal of the rigid distal portion of the core body from the passageway in the mounting member. The mounting member is preferably resilient so that the igniter assembly can move to compensate for thermal expansion effects. In use in an appliance, the mounting member will be seated within a mounting, which may comprise a passageway in a rigid appliance body. Where the location means is a projection or barb, it forces an expansion of the portion of the mounting means that it sits within, so that the mounting means forms an interference fit within the passageway in the mounting in the appliance. If the rigid distal portion extends entirely through the passageway in the mounting in J:\Speci\300 399\300 349\32397,doc.

4 the appliance, the projection still provides an interference fit, preventing the rigid distal portion and mounting member from being withdrawn from the passageway in the mounting in the appliance.

Preferably the insulation is an extruded insulating body which sits closely around the core body and is also able to provide support. The entire gas igniter can be assembled without requiring an adhesive, as the rigid distal portion serves to locate the core body so that the discharge portion is unlikely to move, and the core body can be a close fit with the insulating body. The structure acts as a form of "skeleton" maintaining the physical integrity of the gas igniter assembly.

Preferably, the core body is entirely conductive and the central portion connecting the discharge and distal ends is also a rigid body. The core body therefore forms a single, rigid electrode, with discharge portion, distal portion and central body.

Alternatively to an extruded insulating body being provided, insulation may be deposited directly on the core body, for example by depositing a layer of ceramic thereon.

The distal portion preferably includes a further passageway for receiving a conductor, such as a conductive wire. The distal portion is crimped to the wire received in the passageway.

The mounting member also preferably includes an insulating portion which extends from the mounting member, and, preferably, the insulating portion and mounting member are integral.

An advantage of the igniter assembly of the present invention is that it can be assembled mechanically completely free of an adhesive and other such materials.

Features and advantages of the present invention will become apparent from the following description of an embodiment thereof, by way of example only, with reference the accompanying drawings, in which; Figure 1 is an exploded view of a gas igniter assembly in accordance with an embodiment of the present invention; Figure 2 is a view from the side of the electrode of p the assembly of Figure 1; J:\Speci\300 399\300 349\32397.doc Figure 3 is a side view of a mounting member of the assembly of Figure 1; and Figure 4 is view from the top of the mounting member of Figure 3.

Referring to the drawings, a gas igniter assembly 1 in accordance with an embodiment of the present invention is illustrated. The gas igniter assembly 1 comprises core body 2, in this embodiment being an elongate electrode 2 which comprises a substantially disc-like discharge portion 3, a substantially cylindrical distal portion 4 and a central conductive portion 5 connecting the discharge and distal portions.

The distal portion of the electrode seats within a passage way 6 in a mounting member 7, which is arranged to seat assembly 1 in position in a domestic appliance, such as a cooker. The mounting member 7 seats within the passageway 14 in a mounting 15 of the appliance. The mounting 15 may be a partition in the appliance. The mounting member 7 includes a resilient seat portion 8 which is arranged to enable movement of the electrode within the mounting member 7 to take account of movement due to temperature changes, and an insulating portion 9 which extends to insulate the distal portion 4 of the electrode 2. In this embodiment, the seat 8 and the insulating sleeve portion 9 are integrally moulded.

The central conductive portion 5 is mounted within an insulating body 10, which in this case is an extruded heat resistant plastics insulating body. The insulating body is extruded to such a length that the entire central conductive portion seats within it, with the discharge portion 3 of the electrode 2 extending outwardly from it.

A depression 11 is provided in the mounting member 8, surrounding the passage way 9 at the top to receive the base of the insulating member 10. The distal portion 4 of the electrode has a projecting portion 12 which is arranged to interfere with the inner walls of the passage way 6 of J:\Speci\300 399\300 349\32397.doc -6the mounting member 7 in order to retain the electrode 2 within position in the mounting member 7. Because the mounting member 8 is resilient, the projecting portion 12 distends the mounting member 7 outwardly as indicated by reference numerals 16 and 17. The distended portions of the mounting member 7 therefore apply pressure against the walls of the passageway 14 in the mounting 15, causing the assembly to be retained within the passageway 14.

The entire assembly 1 is mechanically assembled, without any glue. The electrode 2 is safely retained in position by the projecting member 12 and the insulating body 10. The core body forms-a "skeleton", which supports the assembly. The insulating body 10 provides some further support.

The distal portion 4 of the electrode includes a passage way 13 within it for receiving an electrical conductor such as a wire, which it will be crimped to.

In operation, when voltage is applied to the electrode 2, a discharge occurs between the discharge portion 3 and a predetermined portion of the appliance, to create a spark and light a fluid such as gas.

Because the assembly is firmly mechanically held together, there is no need for glue to prevent break down of the device by tracking.

In an alternative embodiment (not shown) the insulating member 10 may be an insulating layer which is extruded onto the insulating body, such as an extruded ceramic.

Electrode 2 is preferably of stainless steel.

Note that the projecting portion 12 may be at any position within the passageway 6. It need not be as shown, but could be further down, relative to passageway 14.

Further, the central conductive portion 5 of the electrode need not be solid, but could be a flexible conductor, such as a wire. The distal portion 4 and the q/ discharge portion 3 are rigid but as long as the wire is of J:\Speci\300 399\300 349\32397.doc 7 the correct length, this will notaffect the assembly. In such an alternative embodiment, the insulating member would be required to provide the major supporting 9structure.

Note that the dimensions shown in the drawings are for illustrative purposes only and may be varied.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

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Claims (3)

1. A gas igniter assembly comprising: a core body having an electrode discharge portion at one end of the core body, the electrode discharge portion being arranged to provide a discharge surface, a rigid distal portion remote from the discharge portion, and a rigid central portion connecting the discharge and distal portions; electrical insulation provided about the core body; and a mounting member including a passageway for receiving the rigid distal portion to mount the core body, the mounting member being constructed of a resiliently flexible material which grips the distal portion and thus holds the gas igniter assembly together.

2. A gas igniter assembly in accordance with claim 1, wherein the igniter assembly is assembled mechanically in the absence of an adhesive.

3. A gas igniter assembly in accordance with claim 1 or claim 2, wherein a locating means is included in the distal portion of the core body to seat the electrode within the mounting member, wherein the locating means is a projection projecting from the distal portion of the core body to provide an interference fit with the passageway in the mounting member, and wherein the resilient mounting member is arranged to be received within a passageway in a portion of an appliance for mounting the igniter, the projection distending the resilient mounting member to facilitate retaining the mounting member within the passageway in the portion of the appliance. Dated this 6 th day of April 2000 UTILUX PTY LIMITED By their Patent Attorneys GRIFFITH HACK J:\Speci\300 399\300 349\32397.doc