GB2154278A - Spark plugs with renewable electrodes - Google Patents

Abstract

The plug comprises a short, insulated centre electrode portion 4 and a long centre electrode portion 7 surrounded by an insulator 5. A locking nut 6 is screwed into a casing 3 to unite the two electrode portions. The nut 6 may be unscrewed to replace the electrode portion 4 when this portion has become eroded. <IMAGE>

Description

SPECIFICATION Re-usable spark plug The present invention relates to ignition spark plugs used in internal combustion engines.

Ignition spark plugs for such engines are well known, in which an intermittent electrical charge is delivered from a distributor, via a high tension cable, to the pick up point of the spark plug, which is in effect, an electrode housed within an insulated body, half of which is held within a metal element, formed and threaded as to be secured within the engine's cylinder head, to a depth suitable to enable co-operation within the combustion area of the engine, with the electrical charge arcing to earth via a metal lug, secured to the metal element which houses the electrode, and insulated body. In operation, the arcing, or (sparking) or the plug, burns away the tip of the electrode, so that after some 5,000 miles, the whole spark plug is rendered useless, and has to be renewed.

The object of the present invention is to provide a spark plug with a replaceable electrode tip, to compensate for the burn factor.

Therefore in essence, the burned electrode tip only, need be simply and cheaply replaced, which significantly reduces the disadvantages sighted above, with reference to the prior art.

This object is achieved, in general principles, by the first aspect of the invention, which provides a spark plug of relevent dimensions, in keeping with all petrol driven internal combustion engines, and constructed with interchangable component pieces. Such an arrangement clearly reduces excessive wastage, compared to conventional spark plugs described above.

According to a second aspect, the present invention provides a spark plug, incorporating an electrode in two relatively sized parts, each of which, being securely encased within an insulating ceramic body, one of which will be interchangable and small in relation, sized and formed to fit within a polydimentional cylindrical element, incorporating an earthing lug, and secured within the relevent engine cylinder head, with the interpositioning of a sealing washer. The second and longer part of the electrode will be placed co-operatingly with the replaceable electrode, and secured by pressure asserted onto annular formations on the peripheral surface of the insulating body, by a locking element, held within the cylindrical element, by way of male to female threading.

It will be appreciated that other methods may be used in constructing and operating the present invention, and will be dealt with by drawings only. The preferred embodiment however, will now be more particularly described, by way of example, with reference to the relevent accompanying diagramatic drawing, in which; Figure 2 is an exploded projection, with insert Figure 2a showing internal formation of one component piece.

Referring now to the drawing, the re-usable spark plug includes a sealing washer 1. For positive sealing between the combustion chamber and the spark plug body. An earth lug 2. joined to a metal spark plug casing 3.

at any point on face 3c. A short insulated electrode 4. housed within casing 3. (See Fig.

2a) with positive sealing by way of an annular seat 3a. and respective annular formations 4a.

A long insulating body 5. over which will be placed a locking element 6. with an annular concave seat 6a. that will co-operate with annular formation 5a. of the insulating body 5. A long electrode 7. will be secured within the length of the body 5. and the tip 7a.

formed to receive the respective high tension cable (not shown). In operation the intermittent charge will be relayed from the large electrode 7. to the replaceable electrode 4. via the co-operation of the formations 4b. and 5b. The co-operation and sealing between 3a and 4a. . 4b. and 5b. will be enforced by the locking element 6. secured by way of threads 6b. and 3b. (see Fig. 2a.) within casing 3.

The electrical charge will then arc to earth via the lug 2. and casing 3. when secured within the relevent cylinder head by way of threads 3d

CLAIMS 1. A spark plug comprising a first and polydimentional casing piece, which includes an earthing lug. an insulated electrode suitably formed in two separate parts, to act co-operatingly and releasingly contained within the above mentioned first casing piece.

A second polydimentional casing piece, formed to retain the two part electrode and be releasingly secured within the first casing piece.

2. A spark plug as claimed in Claim 1.

wherein the first casing piece is provided with internal threading to accomodate the second polydimentional casing piece.

3. A spark plug as claimed in Claim 1. or Claim 2. wherein a suitably insulated electrode is formed to act co-operatingly in two pieces, and suitably retained within the first casing piece.

4. A spark plug as claimed in Claim 1.

Claim 2. and Claim 3. wherein means are provided for the "Tip" or arcing part of the electrode to be replaced when rendered useless or damaged through wear or other means.

5. A spark plug substantially described herein with reference to Figs. 2. and 2a. of the accompanying drawing.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Re-usable spark plug The present invention relates to ignition spark plugs used in internal combustion engines. Ignition spark plugs for such engines are well known, in which an intermittent electrical charge is delivered from a distributor, via a high tension cable, to the pick up point of the spark plug, which is in effect, an electrode housed within an insulated body, half of which is held within a metal element, formed and threaded as to be secured within the engine's cylinder head, to a depth suitable to enable co-operation within the combustion area of the engine, with the electrical charge arcing to earth via a metal lug, secured to the metal element which houses the electrode, and insulated body. In operation, the arcing, or (sparking) or the plug, burns away the tip of the electrode, so that after some 5,000 miles, the whole spark plug is rendered useless, and has to be renewed. The object of the present invention is to provide a spark plug with a replaceable electrode tip, to compensate for the burn factor. Therefore in essence, the burned electrode tip only, need be simply and cheaply replaced, which significantly reduces the disadvantages sighted above, with reference to the prior art. This object is achieved, in general principles, by the first aspect of the invention, which provides a spark plug of relevent dimensions, in keeping with all petrol driven internal combustion engines, and constructed with interchangable component pieces. Such an arrangement clearly reduces excessive wastage, compared to conventional spark plugs described above. According to a second aspect, the present invention provides a spark plug, incorporating an electrode in two relatively sized parts, each of which, being securely encased within an insulating ceramic body, one of which will be interchangable and small in relation, sized and formed to fit within a polydimentional cylindrical element, incorporating an earthing lug, and secured within the relevent engine cylinder head, with the interpositioning of a sealing washer. The second and longer part of the electrode will be placed co-operatingly with the replaceable electrode, and secured by pressure asserted onto annular formations on the peripheral surface of the insulating body, by a locking element, held within the cylindrical element, by way of male to female threading. It will be appreciated that other methods may be used in constructing and operating the present invention, and will be dealt with by drawings only. The preferred embodiment however, will now be more particularly described, by way of example, with reference to the relevent accompanying diagramatic drawing, in which; Figure 2 is an exploded projection, with insert Figure 2a showing internal formation of one component piece. Referring now to the drawing, the re-usable spark plug includes a sealing washer 1. For positive sealing between the combustion chamber and the spark plug body. An earth lug 2. joined to a metal spark plug casing 3. at any point on face 3c. A short insulated electrode 4. housed within casing 3. (See Fig. 2a) with positive sealing by way of an annular seat 3a. and respective annular formations 4a. A long insulating body 5. over which will be placed a locking element 6. with an annular concave seat 6a. that will co-operate with annular formation 5a. of the insulating body 5. A long electrode 7. will be secured within the length of the body 5. and the tip 7a. formed to receive the respective high tension cable (not shown). In operation the intermittent charge will be relayed from the large electrode 7. to the replaceable electrode 4. via the co-operation of the formations 4b. and 5b. The co-operation and sealing between 3a and 4a. . 4b. and 5b. will be enforced by the locking element 6. secured by way of threads 6b. and 3b. (see Fig. 2a.) within casing 3. The electrical charge will then arc to earth via the lug 2. and casing 3. when secured within the relevent cylinder head by way of threads 3d CLAIMS

1. A spark plug comprising a first and polydimentional casing piece, which includes an earthing lug. an insulated electrode suitably formed in two separate parts, to act co-operatingly and releasingly contained within the above mentioned first casing piece.

A second polydimentional casing piece, formed to retain the two part electrode and be releasingly secured within the first casing piece.

2. A spark plug as claimed in Claim 1.

wherein the first casing piece is provided with internal threading to accomodate the second polydimentional casing piece.

3. A spark plug as claimed in Claim 1. or Claim 2. wherein a suitably insulated electrode is formed to act co-operatingly in two pieces, and suitably retained within the first casing piece.

4. A spark plug as claimed in Claim 1.

Claim 2. and Claim 3. wherein means are provided for the "Tip" or arcing part of the electrode to be replaced when rendered useless or damaged through wear or other means.

5. A spark plug substantially described herein with reference to Figs. 2. and 2a. of the accompanying drawing.