CLIAMS:I claim:
1. A spark plug (10) for an internal combustion engine of a vehicle, said spark plug (10) comprising a washer (22) arranged between a shell region (18) and a thread region (25), characterized in that said washer (22) comprises at least one elastomeric element (32).

2. The spark plug (10) of claim 1, said at least one elastomeric element (32) of said washer (22) is a synthetic rubber element.

3. The spark plug (10) of claim 1, said washer (22) comprises said at least one elastomeric element (32) and at least one metallic element (34).

4. The spark plug (10) of claim 3, wherein said washer (22) comprises an elastomeric element (32) interposed between two metallic elements (34).

5. The spark plug (10) of claim 3, wherein said washer (22) comprises the elastomeric element (32) provided adjacent to the metallic element (34).

6. The spark plug (10) of claim 3, wherein the washer (22) comprising at least one elastomeric element (32) and the metallic element (34) dampens tightening torque to the thread region (25) and to an engine cylinder head (30). ,TagSPECI:Complete specification: The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention:
[0001] The invention relates to a spark plug for an internal combustion (IC) engine of a vehicle.
Background of the invention:
[0002] Spark plug is a well known engine component used for igniting air-fuel mixture. Installation of the spark plug in the engine cylinder head has to be done carefully, as the spark plug can be damaged if excessive torque is applied. Improper handling and excessive torque could also damage the thread of the engine cylinder head.
[0003] This may also cause problems like stretching of the spark plug shell, losing of thermal characteristics and damage of the spark plug during its assembly or dismantling in the engine.
[0004] US8844364 patent shows a quality control method of a screwed shaft component such as a spark plug. This patent shows a spark plug with a metallic gasket.

Brief description of the invention:
[0005] The invention discloses a spark plug for an internal combustion engine of a vehicle. The spark plug comprises a washer arranged between a shell region and a thread region. The washer comprises at least one elastomeric element. Example of the elastomeric element is a synthetic rubber element.

[0006] In an embodiment of the invention, the washer comprises one or more elastomeric elements and one or more metallic elements.

[0007] In another embodiment of the invention, the washer an elastomeric element interposed between two metallic elements.

[0008] In yet another embodiment of the invention, the washer comprises an elastomeric element provided adjacent to a metallic element. The washer comprising at least one of the elastomeric element and the metallic element dampens tightening torque to the thread region and to an engine cylinder head, when trying to install the spark plug in the cylinder head.
Brief description of the accompanying drawings:
[0009] Different embodiments of the invention are described with reference to the following accompanying drawings,
[00010] Fig. 1 shows a schematic diagram of a spark plug, in accordance with an embodiment of the invention;
[00011] Fig. 2 shows a schematic illustration of a spark plug installed in an engine cylinder head, in accordance with another embodiment of the invention;
[00012] Fig. 3 shows a spark plug having a washer comprising an elastomeric element, in accordance with an embodiment of the invention;
[00013] Fig. 4 shows a spark plug having a washer comprising an elastomeric element and a pair of metallic elements, in accordance with an embodiment of the invention; and
[00014] Fig. 5 shows a spark plug having a washer comprising an elastomeric element and a metallic element, in accordance with another embodiment of the invention.
Detailed description of the embodiments:
[00015] Fig. 1 shows a schematic diagram of a spark plug, in accordance with an embodiment of the invention. The function of the spark plug 10 is to create a spark at a required time inside the engine to ignite the air-fuel mixture.
[00016] The spark plug 10 comprises a connection terminal e.g. a terminal nut 12 at one end, for connecting to an ignition system. The spark plug 10 comprises an inner central electrode 24 covered by an insulator 14. The insulator 14 portion can also be a corrugated portion. A shell region 18 or housing is formed below the insulator 14. The shell region 18 is otherwise called as a hexagon. A thread region 25 is formed near the electrode end of the spark plug 10. A washer 22 is arranged between a shell region 16 and a thread region 24. A ground electrode 26 is formed at the other end of the spark plug 10. High tension current in the central electrode 24 ionizes the gas present in the gap between the ground electrode tip and the central electrode tip to create the spark and ignite the air-fuel mixture.
[00017] Fig. 2 shows a schematic illustration of a spark plug installed in an engine cylinder head, in accordance with another embodiment of the invention. When the spark plug 10 is installed in a cylinder head 30 of an engine, torque has to be applied carefully.
[00018] Seating of the spark plug 10 on the cylinder head 30 will not be proper, if less torque is applied to tighten the spark plug 10. This may slow down the heat transfer and increase the temperature inside the combustion chamber to high level, which may cause damage to the engine.
[00019] Similarly applying excessive torque to spark plug 10 can cause loosening of the insulator 14 and damaging of thread region 24 and the cylinder head 30.
[00020] The spark plug 10 of the present invention comprises a washer 22 having one or more elastomeric elements 32. The elastomeric elements 32 can be in the form of ring. Further, examples of the elastomeric element 32 can include but not limited to synthetic rubber. Fig. 3 shows a spark plug having a washer comprising an elastomeric element, in accordance with an embodiment of the invention.
[00021] Compared to a normal washer, the washer 22 comprising the elastomeric element 32 such as rubber can take more load and can absorb vibration generated by the cylinder head 30 and it can handle high external pressure thereby loosening of insulator 14 is avoided. Further, transmission of force, pressure and vibration to the housing, insulator 14 and cylinder head 30 are prevented effectively.
[00022] In another embodiment of the invention, the washer 22 can have one or more elastomeric elements 32 and one or more metallic elements 34. Example for the metallic element 34 can include but not limited to, a steel element or steel plate. Fig. 4 shows a spark plug having a washer comprising an elastomeric element and a pair of metallic elements, in accordance with an embodiment of the invention. . In fig. 4, an elastomeric element 32 is interposed between two metallic elements 34.
[00023] In this arrangement, the inner layer of the washer 22 is made of elastomeric element 32 such as synthetic rubber. When the force is applied on the spark plug 10, it is transmitted to the metallic element 34 such as steel washer. If the applied force is more than the specified limit, then the synthetic rubber between the steel plates can accommodate and avoid the force transmission to the below steel plate and to the thread region 25. Thereby the spark plug housing and the engine cylinder head 30 will not be subjected to high torque and thus thread damage is prevented.
[00024] Fig. 5 shows a spark plug having a washer comprising an elastomeric element and a metallic element, in accordance with another embodiment of the invention. In this embodiment, an elastomeric element 32 and a metallic element 34 are arranged adjacent to each other. The metallic element 34 is placed on one side of the elastomeric element 32.
[00025] When the elastomeric element 32 such as synthetic rubber is placed above the metallic element (e.g. steel plate), the elastomeric element 32 receives the entire load and avoid the force transmission to the thread region 25. When the spark plug 10 is tightened more than the specified limit, because of the elastomeric element 32, the spark plug housing and the cylinder head 30 are not subjected to high torque and thus thread damage is prevented.
[00026] Similarly when the elastomeric element 32 (e.g. synthetic rubber) is placed below the metallic element 34 (e.g. steel plate), if the applied force is more than the specified limit, the elastomeric element 32 receives the force even if the metallic element 34 fails to accommodate the force. Thereby the spark plug housing and the engine cylinder head 30 are not subjected to high torque and thus thread damage is prevented.
[00027] Thus the washer of the present invention comprising at least one of the elastomeric element and the metallic element dampens tightening torque to the thread region and to an engine cylinder head, when trying to install the spark plug in the cylinder head.

[00028] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

CLAIMS
I claim:
1. A spark plug (10) for an internal combustion engine of a vehicle, said spark plug (10) comprising a washer (22) arranged between a shell region (18) and a thread region (25), characterized in that said washer (22) comprises at least one elastomeric element (32).

2. The spark plug (10) of claim 1, said at least one elastomeric element (32) of said washer (22) is a synthetic rubber element.

3. The spark plug (10) of claim 1, said washer (22) comprises said at least one elastomeric element (32) and at least one metallic element (34).

4. The spark plug (10) of claim 3, wherein said washer (22) comprises an elastomeric element (32) interposed between two metallic elements (34).

5. The spark plug (10) of claim 3, wherein said washer (22) comprises the elastomeric element (32) provided adjacent to the metallic element (34).

6. The spark plug (10) of claim 3, wherein the washer (22) comprising at least one elastomeric element (32) and the metallic element (34) dampens tightening torque to the thread region (25) and to an engine cylinder head (30).
Dated this 10th day of April, 2015
(Digitally signed)
Kartik Puttaiah
Patent agent of the Applicants (IN/PA-1809)