US1945408A

US1945408A - Spark plug

Info

Publication number: US1945408A
Application number: US604592A
Authority: US
Inventors: Anderson August Eugene
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-04-11
Filing date: 1932-04-11
Publication date: 1934-01-30
Anticipated expiration: 1951-01-30

Description

Jan. 30, 1934. A. E. ANDERSON 1,945,408

SPARK PLUG Filed April 11, 1952 Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE 1 Claim.

My invention relates to a spark plug having the spark gap placed within an insulated chamber, so as to prevent any of the high voltage current from being attracted to any grounded part of the spark plug or other grounded part of the engine, except through the spark gap to the grounded electrode of the spark plug.

Another object of my invention is to place the spark gap so as to keep the same and the electrodes out of the compressed charge of the combustion gases as much as possible. The reason for this is obvious because a compressed charge will act more or less as a conductor to the high voltage current and thereby weaken the spark at the gap. This is best proven when starting a cold motor with the choke out. Under this condition the compressed charge becomes equivalent to a solid conductor which causes the motor to miss.

Still another object of my invention is to construct a plug in such a manner that it will be unafiected by the different temperatures that may be found in various combustion engines while the gap and electrodes are well protected by means of the insulation chamber so that the pre-ignition is at a minimum. The porcelain insulator is so constructed that an annular space is formed around it where the ground electrode passes through, which space is large enough to allow the grounded electrode to expand.

This arrangement of the electrodes and insulated chamber differs from the spark plugs that have been used in the past, where no consideration was given to the spark gap being exposed and directly projecting in the path of the compressed charge of gas in the cylinder.

It is also obvious that a spark gap placed in an insulated chamber, as is clearly shown in the drawing, will have the advantage over the old style spark plugs when the gap is placed below the insulated part of center electrode, in that the resistance at the gap is cut down, thereby giving a hotter spark at all times and chances of fouling becomes a minimum.

In the accompanying drawing, one embodiment of my invention is shown and Fig. 1 is a vertical axial section of the spark plug and Fig. 2 a horizontal section along line 2-2 of Fig. 1.

In the drawing, reference numeral 10 represents the metal body or housing of the plug and 12 the porcelain insulator or dielectric core member fitting closely in the hollow space formed in said body. The dielectric has an upwardly tapering shoulder 20 merging into the neck portion 21 extending through the central opening formed in the securing nut 11, which engages the shoulder 20 and is preferably threaded in the plug body as at 22.

The dielectric has also a downwardly tapering shoulder 23 terminating with a narrow shank 24 stopping short of the lower externally threaded end 19 of the body, which in the usual manner screws into the cylinder head of the internal combustion engine.

Around the shank 24 of the dielectric is formed an annular space 14 in the lower end 19 of the metal body to permit expansion and cooling. In the lower end or shank 23 is provided a downwardly open, small chamber 13 into which projects the free end of the electrode 15 which runs in axial direction completely through the dielectric or porcelain insulator 12 engaging with the leading in wire 16 clamped in position by the screw cap 17.

The ground electrode 18 is secured in the threaded end 19 of the body and runs in radial direction therethrough and across the annular space 14, through the dielectric shank 24 and projects with its spark point into the chamber 13 so as to form the spark gap 25 between its point and the point of the axial terminal 15.

It will thus be seen that, because the spark gap is located within the chamber 13, the ends of the terminals are not exposed to the hot flame or combustion gases and will, therefore, not wear away as is usual with other spark plugs. Furthermore, because of the annular chamber 14, not only the shank 24 of the dielectric but also the ground electrode will find room for expansion.

I claim:

In a spark plug the combination of a hollow metal housing and a dielectric core member seated therein, oppositely directed upper and lower shoulders on the core member and housing respectively, adapted to make firm connection between them, a narrow shank at the lower end of the core member having a downwardly open chamber, an annular space being formed around said shank in the housing, a main electrode carried by the core member projecting with its spark point into said chamber, and a ground electrode secured in the threaded portion of said housing and extending across said annular space through said shank and projecting with its spark point substantially radially into said chamber, thus forming with the point of the main electrode a spark gap within said chamber, said shank and electrodes having room for expansion within said annular space.

AUGUST E. ANDERSON.