US2904769A - Spark plug nipple - Google Patents

Description

Sept. 15, 1959 1.. R. SAMPSON 2,904,769

SPARK PLUG NIPPLE Filed July 10. 1953 INVE NTO R5 MmemczmrmwWJo/r ATTORNEY United States Patent SPARK PLUG NIPPLE Lawrence 'Raymoud Sampson and George W. Lampman,

Pontiac, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 10, 1953, Serial No. 367,208

1 Claim. (Cl. 339-26) to protect the electrical connection made between the ignition cable and the spark plug terminal. The accumulation of dirt, dust, road salt including sodium and calcium chloride, and oil contaminates the connection and disrupts the normal operation of the ignition system. The condensation of moisture on the plug and exposure to water likewise disrupt the operation of the system by shorting out the plug. To this end, rubber spark plug nipples which are intended to protect the connection have long been in common use.

A spark plug nipple found in common use at the present time is the elbow or straight shield which requires press fit at both the cable end and the plug end. However, experience has proved that installation of this type of nipple over the spark plug is difiicult and that it is difiicult to determine whether or not positive lock of the ignition cable terminal clip to the spark plug terminal has occurred during assembly. Furthermore, because of the general shape and design of present production nipples, removal from the plug insulator without damage is problematic. This is particularly so after a relatively short period of operation, the heat of the engine acting to bake the nipple to the insulator.

In addition, the nipples in present production tend to lose their sealing properties, as presently constructed. A large amount of air space in the communicating portions of the nipple permits the formation of a relatively large amount of ozone which accelerates the cracking process of the rubber shield and replacement is necessary within a relatively short time.

Accordingly, it is an object of our invention to provide a spark plug nipple having a minimum amount of internal air space.

It is a further object of our invention to provide a nipple that is easily installed and forms an effective seal.

It is a further object of our invention to provide a nipple that is easily disassembled and forms an effective seal.

It is a still further object of our invention to provide a nipple that is free from assembly and disassembly problems and at the same time retains positive sealing action.

To attain these objects, We provide a spark plug nipple having a plurality of spaced sealing lips formed on the inner wall of the nipple and a flange-like collar on the outer wall substantially at the plane of junction of the upper and lower portions of the nipple.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, Wherein a preferred form of the present invention is clearly shown.

, 2,904,769 Patented Sept. 15, 1959 In the drawing:

Figure l is avertical sectional view of the nipple of our invention.

Figure-2 is an enlarged view of the lower portion of the nipple shown in Figure 1.

Referring now to the drawing and more particularly to Figure 1 there is shown a spark plug 1 having a central insulator member 3 and a terminal 5. It should be noted that, as is generally the case, the plug terminal is smaller in diameter than the plug insulator thus forming a plug shoulder 7. Sparking power is supplied to the plug through an ignition cable 9 shown as held in disconnectable electrical contact with the terminal 5 by terminal clip 11 which is securely fastened to the cable.

In order to protect the cable-plug connection from weather and contamination we provide a nipple 13 made of a resilient rubber-like insulating material such as neoprene, Butyl rubber or other suitable material. As shown in Figure 1, the nipple of our invention is straight and is provided with two communicating sections 15 and 17, the longitudinal axis of the upper cable receiving section 15 being coincident with the longitudinal axis of the lower plug receiving section 17.

The diameter of the passageway in the upper section is but slightly larger than the diameter of cable 9 positioned therein. Likewise the diameter of the passageway in the lower section is but slightly larger than-the diameter of the plug insulator 17 on which it is posia tioned. In this manner the air space within the nipple is reduced to a minimum with the substantial elimination of ozonation and the accelerated ageing caused thereby.

Positive sealing action is attained by the provision of a plurality of spaced ring-like sealing lips 19 on the inner wall of the upper and lower sections 15 and 17 of the nipple as shown in Figure 1. Sealing lips 19 are of such size as to be in intimate contacting relation with the plug insulator 3 and cable 9 and thus provide a series of efiicient barriers to moisture and/ or dirt. Each pair of adjacent sealing lips in contacting relation with the insulator and cable defines an annular chamber 21 which serves to trap any moisture and/or dirt, each chamber functioning as a guard chamber to those successively closer to the cable-plug terminal connection. In this manner, just as in the case of poison gas safety chambers which are provided with a plurality of entrance locks as standard construction, the innermost chamber is eifectively sealed against contamination.

At the same time, sealing lips 19 permit the assembly of the nipple about the cable 9 and the plug insulator 3 with substantially no difliculty because of the greatly reduced contact area which results in less friction. Further, it should be noted that the chambers 21 result in a markedly greater degree of pliability that is obtainable in the various structures of the prior art which depended on comparatively non-pliable construction for obtaining the desired sealing action. As shown more clearly in Figure 2, the contacting surface 23 of each sealing lip is substantially flat. However, this surface may be of other configuration such as triangular, concave or convex with substantially equal effectiveness.

Applicants further provide an internal positive stop 25 which, when the nipple is completely installed, seats against the spark plug shoulder 7 and insures both proper positioning of the nipple and complete and positive locking of the clip 11 to the terminal 5. Stop 25 is formed at the plane of junction of the cable passageway with the relatively larger insulator passageway, the two passageways being joined shaiply. Positive locking of the clip and terminal are further assured by the provision of a collar 27 on the inner wall of the cable passageway. Inner collar 27 has substantially the same inside diameter aszthat of clip-1L andzis .formed immediately adjacent the plane ofjunction of the two passageways. The cable and clip may be installed "in th'eupper section of 'th'emipple" with the inner collar 27 on the lower end of the clip thus forming a sub-assembly which will retain its relative positioning while being installed on the terminal'i Installation and removal of the above" defined? subassembly is greatly facilitated by the provision". of a grip, shown as circumferential 'collar'29, on the exterior'of the nipple. As is more clearly shown in Figure2of the drawing, collar; 29 'is'positioned just behiridthe plane of jllIlCl'iOIlLOf the .two'nipple passageways and is coextensive withthe inner coll'ar27i At installation, this grip, provides a'convenient finger locationipoint andpressure area. Duringjremovah'. pull on' this grip automatically tends to distortthe:sealing port ion atlth'e plug endof the nipple away from the insulator,,thus reducing, the adhering loads. As pointed .out' 'hereinbeforqthe opposite effect occurs with the nipplsin'present production.

While. the formof the embodiment ofithe invention as herein disclosedconstitutes a preferred form, it is to be understood that other forms might be adopted, for example", the, substance ofappliiz'ants invention might be applidto angleand universal type nipples, as may come within the scope of the attached .l claim.

What-is claimed is:

In combination with asparkplugand ignition cable assembly wherein the ignition cable. isseeured'to the plug terminalby meansof'a metal clip, avnipple. comprisinga tubular member of Tresilient insulatingimaterial having ppper and lower communicating sections, the longitudinal. axes. of said sections. being ,co-incident and. the inside diameter of'each section being relatively slightly largenthan. the cable 1 and the spark plugportion. over which" saidfinipple is assembled, means on theendiportion of said uppersection-= sealingly engaging said ignition cable, a plurality of spaced ring-like sealing lips provided on tlie'innerwall of said'lower section'intimatelvcontacting said plug over a small surface area to enable ready removal therefrom, an internal stop formed at the plane of junction of said sections and seated on the end of said plug, a flange-like collar 'formed integral with the outer wall of said nipple: adjacent said plane, and a relatively small collar formed. onwthe inner surface of said upper section andcmextensive with" said first-mentioned collar, said flangelike collar: outwardly;v distorting; the sealing portion of f'the plug end-ofisaid nipplestobreak adherence between: said :sealing lips and: said plug upon the application of-a pulling force-to said firsbmentioned collar, and'said'relatively small collar having an internal diameter substantiall-y'the same asith'at .of the metal clip to enable assembly of the nipple and metal clip upon the plug as a subassembly to assure positive locking of the clip on the plug, terminal.

References Cited in the file of this'p'atent' UNITED STATES PATENTS 561,441 Schmidt June 2, 1896 1,117,840) Hamilton Nov. 17, 1914 1,245,931 Lanman Nov. 6, 1917 1,723,765 Churchill Aug. 6,-1929 1,926,197 Durr Sept. 12, 1933 2,167,865 Beecher Aug. 1, 1939 2,189,987 Kellems Feb. 13, 1940 2,550,358 Le Grand" .Apr. 24, 1 2,665,673 Woofter Ian. 12, 1954 2,690,541 Elliott Sept. 28,1954 2,704,355 HOltOn Mar. 15, 1955 2,750,573 Mika' June.13, 1956

Images