US3128139A

US3128139A - Spark plug shield

Info

Publication number: US3128139A
Application number: US38976A
Authority: US
Inventors: Stanley E Estes
Original assignee: HALLETT Manufacturing CO
Current assignee: HALLETT Manufacturing CO
Priority date: 1960-06-27
Filing date: 1960-06-27
Publication date: 1964-04-07
Anticipated expiration: 1981-04-07

Description

April 1964 s. E. ESTES 3,128,139

SPARK PLUG SHIELD Filed June 27, 1960 INV TOR. SrAM/LEY $755 wid/ ml i plug 11.

United States Patent Ofi ice 3,128,139 Patented Apr. 7., 1964 3,128,139 SPARK PLUG SHIELD Stanley E. Estes, Inglewood, Califi, assignor to Hallett Manufacturing Company, Los Angeles, Calif., a corporation of California a Filed June 27, 1960, Ser. No. 38,976 8 Claims. (Cl. 339-26) boats, as well as in stationary installations embodying radio equipment where these installations are proximate internal combustion engines seriously diminishes the utility of the radio receiving and transmitting apparatus.

By enclosing thevarious elements of the ignition system within a metallic electrically conductive housing which is grounded, the electrical radiations from the sys' tem will be dissipated in the ground and the interference eliminated. In the case of spark plugs themselves they have been shielded by building a metallic housing into the plug itself which is expensive and not otherwise fully satisfactory. Iam also aware of a separate spark plug housing, but this type renders the spark plug ditficult of access 'as well as other faults which I have eliminated by my present invention.

A broad object of my inventionis to provide a compact electrical shielding for a spark plug which will substantially prevent transmission of electricalradiation.

A further object of my invention is to provide an improved shielding for a spark plug which serves the additional function of physical protection against weather.

, Still another object of my invention is to provide a spark plug shield of light weight, simple construction, and which can be readily assembled or disassembled and which nevertheless serves thefunction of shielding with maximum efiiciency: Y 7

Still another object of my invention is to provide a new and improved shield for a spark plug which incorporates a simplified mounting on the spark plug permitting it to be installed on the plug and removedwithout the use of special tools.

With these and-other objects in'view, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained as hereafter more fully set forth, pointed out in the claims, and illustrated in the accompanying drawings,'in which:

FIGURE 1 is a side elevational cross section view of my spark plug shield;

FIGURE 2is a view similar to FIGURE 1 wherein the shield is mounted on a spark plug;

FIGURE 3 is a cross section taken on line 3--3 of FIGURE 2.

My spark plug shield is indicated by the reference numeral which is adapted to fit on a spark plug 11 which is installed in a cylinder head 12 of an internal combustion engine.

The spark plug shield comprises an enlarged tubular electrically conductive housing 13 of sufiicient diameter to accommodate the hexagonal shoulder 14 of the spark The upper portion of the tubular housing 13 is tapered forming a conical neck portion 15 and a cylindrical end portion 16 having an inside diameter suflicient to receive an electrical cable 17 An insulating member 20 is formed with an annular 2. shoulder 21 at its upper end resting against the upper end of conical neck portion 15 of the tubular housing 13. The insulating member 20 extends downward from the annular shoulder 21 to a position in the tubular housing 13 shown in FIGURESl and 2. The insulating member 20 ends has an annular shoulder portion 22 with a diameter substantially the same asthe inside diameter of the tubularhousing 13 so that when the insulating member 20 is inserted in the tubular housing 13 the shoulder 22 will engage the interior of the housing 13 and frictionally hold it in position as illustrated in FIGURES l and 2. It should be noted that to insure permanency the shoulder 22 may be cemented to the interior of the housing 13. The insulating member 20 is further formed with an opening 23 extending through the insulator. The central portion of the insulator opening 23 is enlarged at 24 to receive the electrode terminal 25 and porcelain insulator 26 of the spark plug. The elongated enlarged portion 24 is substantially the same diameter throughout but at its lower end is reduced in diameter forming an annual gripping portion 24' which will accommodate and frictionally engage ribs 27 of the'spark plug 11, or in the case of spark plugs having smooth surfaced insulators, the smooth surface will be engaged by gripping portion 24'. It should be noted that the diameter of the central portion 24 is Wider than the insulator portion 26 when inserted and there is formed an annular air space around the insulator portion 26. This air space creates an air thermal insulation between the spark plug insulator and the spark plug shield, thus'maintaining a relatively loW temperature on the exterior of the shield. An elongated electrical grounding spring clip 28 is positioned between the annular shoulder 22 of the insulator and the inside surface of the tubular housing 13. This clip 28extends downward parallel to and engaging the housing 13 to a pointwhere it is bent inward forming a portion 29 which engages the hexagonal shoulder 14 of the spark plug 11 as best shown in FIGURE 2. With the use of this grounding spring clip 28 any electrical radiation which may be traveling along the tubular housing 13 will pass to the clip, then to the metal shell of the spark plug and thence to the cylinder head 12.

At the upper end of the enlarged opening 24 of the insulator an outwardly extending annular shoulder 30 of a terminal conductive connector 32'engages a shoulder 31 of the insulator. An upper threaded screw portion 33 of connector 32 is threaded into the wire end portion 34 of cable 17. A nonconductive collar 35 is fitted around the cable 17 in the opening 23 to further hold the cable in position on the connector 32.

The cable 17 extends upward from the connector 32 snugly through the opening 23 in the insulator and out the elongate cylindrical end portion 16 to an electrical distributor cap not shown.

The cable 17 between the distributor cap and the end portion 16 of the housing is shielded with tinned copper braid 36 which affords substantial metallic conductive coverage of the cable. The braid or mesh 36 does not enter the end portion 16 but is spread so that it will fit over the end portion 16 as shown in FIGURES l and 2. An outer collar 37 is fitted and crimped over the mesh to hold it to the neck portion 16. Thus by the contact of the mesh with the portion 16 of tubular housing 13 the grounding of any electrical radiation will be complete from the braid to the tubular housing to the spark plug to the motor.

While the invention has been shown and described herein in What is conceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed hereat a point at least midway between the respective.

in but is to be accorded the full scope of the claims and so as to embrace any and all equivalent apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Electrical shielding means for use with a spark plug of an internal combustion engine which spark plug comprises a conductive shell including a wrench shoulder formed thereon, a porcelain insulator mounted on said shell and an electrode terminal projecting from said insulator, said electrical shielding means comprising an electrically conductive tubular housing including a first open ended section of relatively large diameter adapted to receive the spark plug, a second open ended section of relatively small diameter, and an intermediate section conductively connected with the first and second sections, an insulator member mounted within said housing including an annular enlarged portion engaging said tubular housing and reduced portions projecting from said enlarged portion into said intermediate section and said first open ended section respectively, said reduced portions radially spaced from said intermediate section and said first open ended section respectively of said housing, said insulator member formed with a bore extending entirely therethrough, said bore including an annular end portion which is adapted to frictionally engage a section of the porcelain insulator spaced from said wrench shoulder, whereby said housing is adapted to be retained in spaced relation from said spark plug, an electrode terminal conductive cap mounted in said insulator bore adapted to frictionally engage said electrode terminal and stabilize said tubular housing about said spark plug, an insulated conductive cable extending through said second open ended section and said insulator bore and conductively connected with said electrode terminal cap, said cable being provided with external conductive sheathing terminating on the second open ended section and conductively connected thereto and providing electrical grounding therewith, and a second ground connection extending from the housing adapted to engage the conductive shell of said spark plug.

2. Electrical shielding means as defined in claim 1 wherein said second ground connection is a conductive spring clip engageable with the wrench shoulder of said spark plug.

3. Electrical shielding means as defined in claim 1 wherein the axis of each of said first open ended section, said second open ended section and said intermediate section lie on the same line.

4. Electrical shielding means as defined in claim 3 wherein said intermediate section is tapered from said second open ended section to said first open ended section.

5. The combination of: a spark plug for an internal combustion engine comprising an electrically conductive shell including a wrench shoulder formed thereon, a porcelain insulator mounted on said shell and an electrode terminal projecting from said insulator, an electrically conductive tubular housing including a first open ended section of relatively large diameter receiving the spark plug, a second open ended section of relatively small diameter, and an intermediate section conductively connected with the first and second sections, an insulator member mounted within said housing including an annular enlarged portion engaging said tubular housing and reduced portions projecting from said enlarged portion into said intermediate section and said first open ended section respectively, said reduced portions radially spaced from said intermediate section and said first open ended section respectively of said housing, said insulator member formed with a bore extending entirely therethrough, said bore including an annular end portion which frictionally engages a section of the porcelain insulator spaced from said wrench shoulder, whereby said housing is retained in spaced relation from said spark plug, an electrode terminal conductive cap mounted in said insulator bore to frictionally engage said electrode terminal and stabilize said tubular housing about said spark plug, an insulated conductive cable extending through said second open ended section and said insulator bore and conductively connected with said electrode terminal cap, said cable being provided with external conductive sheathing terminating on the second open ended section and conductively connected thereto and providing electrical grounding therewith, and a second ground connection extending from the housing engaging the conductive shell of said spark plug.

6. The combination as defined in claim 5 wherein said second ground connection is a conductive spring clip engageable with the wrench shoulder of said spark plug.

7. The combination as defined in claim 5 wherein the axis of each of said first open ended section, said second open ended section, and said intermediate section lie on the same line.

8. The combination as defined in claim 5 wherein said intermediate section is tapered from said second open ended section to said first open ended section.

References Cited in the file of this patent UNITED STATES PATENTS 1,167,820 Herz Jan. 11, 1916 1,765,443 Peterson June 24, 1930 1,909,248 Benkelman May 16, 1933 2,071,572 Rabezzana et al Feb. 23, 1937 2,113,590 Hiscock Apr. 12, 1938 2,133,789 Pool Oct. 18, 1938 2,286,918 Mascuch June 16, 1942 2,296,054 Rabezzana Sept. 15, 1942 2,673,233 Salisbury Mar. 23, 1954 2,730,562 Marden Ian. 10, 1956 2,863,131 Carlzen et al. Dec. 2, 1958 2,876,274 Cole et al. Mar. 3, 1959 FOREIGN PATENTS 167,659 Great Britain Aug. 18, 1921 374,948 Great Britain June 20, 1932 231,329 Switzerland June 1, 1944 146,131

Australia Dec. 22, 1949