US3917374A

US3917374A - Electric connector apparatus

Info

Publication number: US3917374A
Application number: US498723*[A
Authority: US
Inventors: Robert E Murdock
Original assignee: Kearney National Inc
Current assignee: Kearney National Inc
Priority date: 1974-08-19
Filing date: 1975-08-19
Publication date: 1975-11-04
Anticipated expiration: 1992-11-04
Also published as: BR7502004A; CA1019819A

Abstract

An electric terminal such as a transformer bushing having a contact socket of conducting material is provided with a quench tube arranged in aligned substantially coaxial relation with the contact socket and constructed of an inner sleeve of arc extinguishing material and an outer sleeve of mechanically strong plastic material. Peripheral grooves are formed about the inner surface of the quench tube and resilient grommets are disposed in the grooves. An associated connector which may be of the elbow type is provided with a contact pin which includes a tubular element of conducting material to the end of which a stem of mechanically strong plastic material is affixed to support a hollow sleeve disposed thereabout and formed of arc extinguishing material and which is bevelled at its outer end to facilitate entry of the contact pin into and through the quench tube and into the contact socket so as to form a connection between the contact socket and the tubular element of conducting material.

Description

United States Patent [191 Murdock Nov. 4, 1975 1 ELECTRIC CONNECTOR APPARATUS Robert E. Murdock, Stone Mountain, Ga.

[73] Assignee: Kearney-National Inc., Atlanta, Ga.

[22] Filed: Aug. 19, 1975 [21] Appl. No.: 498,723

[75] Inventor:

[52] US. Cl. 339/111; 339/59 R; 339/143 R; 339/272 R [51] Int. GL H01R 13/52 [58] Field of Search... 339/111, 143 R, 59 R, 60 R, 339/61 R, 94 R, 272 R Primary Examiner-Roy Lake Assistant Examiner-DeWalden W. Jones Attorney, Agent, or Firm-Walter M. Rodgers [57] ABSTRACT An electric terminal such as a transformer bushing having a contact socket of conducting material is provided with a quench tube arranged in aligned substantially coaxial relation with the contact socket and constructed of an inner sleeve of arc extinguishing material and an outer sleeve of mechanically strong plastic material. Peripheral grooves are formed about the inner surface of the quench tube and resilient grommets are disposed in the grooves. An associated connector which may be of the elbow type is provided with a contact pin which includes a tubular element of conducting material to the end of which a stem of mechanically strong plastic material is affixed to support a hollow sleeve disposed thereabout and formed of arc extinguishing material and which is bevelled at its outer end to facilitate entry of the contact pin into and through the quench tube and into the contact socket so as to form a connection between the contact-socket and the tubular element of conducting material.

12 Claims, 7 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of2 3,917,374

US. Patent Nov. 4, 1975 Sheet2 0f2 3,917,374

/jinnmm FIG 7 ELECTRIC CONNECTOR APPARATUS Quench tubes for use in connection with electric terminal bushings are formed of arc extinguishing material which is extremely proficient in extinguishing electric arcs. In like fashion the nose portion of known contact pins which cooperate with known quench tubes associated with electric bushings are also formed of highly efficient arc extinguishing material. Difficulties encountered in connection with elements formed of certain arc extinguishing materials are usually due to the mechanical brittleness of the arc extinguishing material. Since connector apparatus is frequently subjected to heavy duty rough usage, elements formed of highly proficient arc extinguishing materials frequently are chipped or broken and hence rendered useless under many service conditions.

Plastic materials are known which are very strong mechanically and which are well adapted to withstand a high degree of mechanical stress. Unfortunately such strong materials are not well suited for use as arc extinguishing materials.

According to the present invention, advantage is taken of the highly proficient arc extinguishing characteristics of known are extinguishing materials and also of known mechanically strong plastic materials and such materials are combined in such a way that compensation for the brittle characteristics of known proficient arc extinguishing materials is achieved by use of a mechanically strong plastic material which is not required to perform an arc extinguishing function. More specifically a quench tube is formed according to this invention and comprises an inner sleeve of arc extinguishing material and an outer sleeve of mechanically strong plastic material. The outer or entry end of the quench tube is constructed so that the strong outer plastic material completely overlies the outer end of the inner sleeve while the inner sleeve is arranged to protrude inwardly beyond the inner end of the outer sleeve. Thus by this construction the inner sleeve is mechanically protected from collision with the contact pin and the inner end of the outer sleeve is shielded from the deleterious effects of arcing. In addition at least one peripheral groove is formed about the inner surface of the quench tube and a grommet formed of resilient material is seated within the groove to guide the contact pin through the quench tube and to seal the tube against undesired expulsion of highly ionized products of arcing. Preferably at least two parallel peripheral grooves are formed about the inner surface of the quench tube and associated resilient grommets are disposed therein so as effectively to guide and align the associated contact pin during circuit opening and closing operations. According to another feature of the invention the inner end of the contact pin is provided with a contact stem which is coaxially disposed with respect to the conducting part of the contact pin and is formed of mechanically strong plastic material and an outer sleeve of arc extinguishing material is disposed about the inner stem and its inner end is bevelled to facilitate entry into the quench tube 14. According to another modification of the invention, the end of the stem remote from the conducting part of the contact pin is provided with a cap for holding the sleeve of arc extinguishing material securely in place and the extreme outer end of the cap preferably is bevelled to aid in 2 aligning the contact pin structure with the resilient grommets.

For a better understanding of the invention reference may be had to the following detailed description taken in conjunction with the accompanying drawings in which FIG. 1 is a view partially in section of a bushing connector and associated quench tube together with an elbow type connector with the parts shown in an open circuit position for clarity;

FIG. 2 is a top view of a quench tube constructed according to this invention;

FIG. 3 is a cross-sectional view taken along the line designated 33 in FIG. 2;

FIG. 4 is a perspective view of a contact pin constructed according to one form of the invention;

FIG. 5 is a view partially in section taken along the line designated 5-5 in FIG. 4;

FIG. 6 is a perspective view of a contact pin formed according to another form of the invention and in which;

FIG. 7 is a view partially in section and taken along the line designated 7-7 in FIG. 6.

With reference to FIG. 1, the numeral 1 generally designates an elbow connector of conventional con struction while the numeral 2 generally designates a bushing connector of more or less conventional construction and which cooperates with the elbow connector 1 to form a connection between an outside conductor such as is designated by the numeral 3 and electric apparatus which may constitute a transformer winding, one terminal of which is designated by the numeral 4, the bushing 2 being mounted within an aperture formed in the transformer casing (not shown) and supported therein by suitable known support ring 5.

The elbow connector 1 comprises a contact pin having a rod-like or tubular conducting part 6 and a coaxially arranged part 7 formed of arc extinguishing material both of which are cylindrically configured together with insulating housing structure 8 about which is disposed elastomeric conducting material 9. A hook 10 is arranged to receive an end of a clamp stick by which the connector 1 is manipulated.

The bushing connector 2 comprises a contact socket 11 the upper end 12 of which is open. Slots 13 are formed in the sides of contact socket 11 to render the upper end of the contact socket expandable for receiving the

contact pin

6, 7.

The quench tube 14 is provided with exterior threads 15 which cooperate with internal threads formed within the support structure comprising inner metallic conductive sleeve 16 which is received within a cavity formed within insulating housing support 17. Insulating housing support 17 is provided with elastomeric conducting material 18 which is grounded to bracket 5 and in turn to the tank of the associated apparatus such as a transformer.

In order to complete a circuit between conductors 3 and 4, the elbow connector 1 is manipulated in such a manner as to cause the skirt 8 to envelope the housing support structure 17 and so as to cause the arc extinguishing part 7 to pass through the quench tube 14 and downwardly into the contact socket 11. Of course when the lower end 6a of the conducting tube 6 enters the open end of contact socket 11 and engages the contact fingers defined by slits 13, the circuit is complete.

When the connector 1 is withdrawn, an arc is established between the end portion 6a of conducting portion 6 of the contact pin as the lower end 6a clears the upper end 12 of the contact socket 11. The are is extinguished by are extinguishing portion 7 of the contact pin and by the quench tube 14.

The quench tube 14 is formed according to one aspect of this invention and comprises an inner sleeve 19 and an outer sleeve 20. Inner sleeve 19 is constructed of arc extinguishing material which is very effective in extinguishing electric arcs. Outer sleeve 20 is constructed of mechanically strong plastic material. The outer sleeve is provided with an outer end portion 21 which completely overlies the outer end portion 22 of the inner sleeve 19. From FIG. 3, it is apparent that the outer end 22 of the inner sleeve 19 is completely protected from inadvertent collision with the end 7a of the contact pin. Since the'inner end 23 of the inner sleeve 19 protrudes inwardly beyond the inner end 24 of the outer sleeve 20, it is apparent that the outer sleeve 24 is completely shielded from contact with electric arcs which are formed between the end 6a of conducting tubular pin 6 and the upper end 12 of the contact socket 11.

For the purpose of efficiently aligning and guiding movement of the

contact pin

6,7 through the quench tube 14 and for sealing these parts against the expulsion of products of an arcing operation, at least one groove is formed about the inner periphery of the quench tube 14 and a grommet formed of resilient material is seated within such groove. Preferably a pair of grooves and 'their associated resilient grommets commonly called O-rings are employed as shown in FIG. 3. One groove and its associated resilient grommet are collectively designated in FIG. 3 by the numeral 25 while the other groove and its associated grommet are designated by the single numeral 26. Preferably, one groove and associated O-ring 25 should be disposed at the junction between the outer end 22 of the inner sleeve 19 and the end portion 21 of the outer sleeve 20.

For the purpose of facilitating a snug assembly of the quench tube 14 within the upper end of the sleeve 16 disposed within the housing support structure 17, a pair of recesses designated by the

numerals

27 and 28 are formed in the upper end portion 21 of the outer sleeve 20. Thus a tightening tool not shown but having a pair of projections is arranged with the projections inserted into the

recesses

27 and 28 and then rotated to tighten or loosen the threads 15 and their associated threads formed within the

structure

16,17.

.The contact pin shown in FIGS. 4 and is constructed according to one aspect of the invention and comprises a tubular conducting part 6 to the inner end 6a of which is secured a stem 7b formed of mechanically strong plastic material. The stem 7b is firmly secured within a recess 6b formed within the conducting part 6 of the contact pin. This securement may be by means of threads, adhesive or by any other suitable means. Disposed about the stem 7b is a sleeve 7c formed of arc extinguishing material. Since arc extinguishing material is mechanically brittle, and because the stem 7b is mechanically strong but formed of material which is not particularly effective as an arc extinguishing material, the result is a mechanically strong highly effective arc extinguishing structure. According to one aspect of the invention, the inner end of sleeve 70 is bevelled as indicated at 7d to facilitate entry of part 7 into quench tube 14 and in contact socket 11.

The threaded end of conducting tubular structure 6 is threaded into a suitable conductor such as a contact block as disclosed and claimed in US. Pat. No. 3,768,065 granted Oct. 23, 1973. The aperture 6d in conductive pin 6 is simply for the purpose of receiving a part of a tightening tool whereby the contact pin is screwed into the contact block.

A contact pin constructed according to another aspect of the invention and as shown in FIGS. 6 and 7 is similar to the arrangements of FIGS. 4 and 5 except that the inner end of the stem is provided with a cap designated by the numeral 7e which is bevelled as indicated at 7f, the cap 7e being integral with the stem 7g. Of course the stem and cap are formed of strong plastic material and the inner end is secured to the conducting tube 6 by adhesive or by any other suitable means. The outer sleeve 7/1 is formed of arc extinguishing material. One advantage afforded by the structure of FIGS. 6 and 7 is attributable to the cap 7e which is of mechanically strong plastic material and which therefore shields the end 7i of sleeve 7/1 from collision with the outer end of the quench tube.

From the above description, it is apparent that by the invention both the contact pin and the quench tube are constructed in such manner as to take advantage of the arc extinguishing properties of the brittle sleeves such as 70, 7/1 and 19 and advantage is also taken of the strong mechanical properties of the plastic stems such as 7b and 7g and of the protective outer sleeve 20. In addition, the resilient grommets or O-rings and their associated grooves designated 25 and 26 serve to align and guide the contact pin into efficient sliding telescopic relation with respect to the quench tube 14 and the contact socket 11 while simultaneously sealing the structure against undesired escape of gases through the upper end of the quench tube 14. If such gases were to escape and be driven by the structure 8 of the elbow connector 1 downwardly into contact with the transformer tank, such action might result in a short circuit of the conductive elements of the transformer to ground by establishing a conductive path upwardly through the bushing 2 and then downwardly around the outside thereof and into contact with the grounded tank. Furthermore, since the O-rings and the

contact pin

6,7 seal the upper end of quench tube 14, pressure in the region of the arc is elevated during the initial portions of an interrupting operation and such increased pressure tends to facilitate extinguishment of the arc. Furthermore since the tightening recesses 27 and 28 are formed in the mechanically strong outer end portion 21 of the outer sleeve 20, it is possible to effect a tight and snug fit between the threaded portion 15 of the quench tube 14 and the associated internal threads of sleeve 16 without imposing deleterious mechanical stresses on the brittle tube 23.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Electric connector apparatus comprising a tubular contact pin, a tubular contact socket of conducting material having at least one open end arranged to cooperate with said contact pin, and a hollow tubular quench tube disposed at said one end of said contact socket and arranged in substantially aligned coaxial relation therewith so as to accommodate telescopic movement of said contact pin relative to said contact socket and quench tube, said tube being of composite construction and including an innersleeve of arc extinguishing insulating material and an outer sleeve of mechanically strong plastic material.

2. Apparatus according to claim 1 wherein said outer sleeve includes an outer end portion at the end thereof remote from said contact socket which completely overlies the outer end of said inner sleeve so as to prevent said contact pin from colliding therewith.

3. Apparatus according to claim 1 wherein said inner sleeve includes an inner end portion adjacent said one end of said contact socket which protrudes inwardly beyond the inner end of said outer sleeve so as to shield said outer tube from contact with an electric arc drawn between said contact pin and said contact socket.

4. Apparatus according to claim 1 wherein at least one groove is formed about the inner periphery of said quench tube and wherein a resilient grommet is seated within said groove for guiding said contact pin and for sealing said tube.

5. Apparatus according to claim 4 wherein said groove is disposed at the junction between the outer end of said inner sleeve and the adjacent part of said outer end portion of said outer sleeve.

6. Apparatus according to claim 1 wherein a plurality of axially spaced grooves are formed about the inner periphery of said quench tube and wherein a plurality of resilient grommets are sealed within said grooves respectively, the inner peripheries of said grommets being configured to accommodate axial movement of said pin through said tube.

7. Apparatus according to claim 2 wherein said contact socket and said quench tube are disposed within a hollow support at least a portion of which is internally threaded to cooperate with external threads on said outer sleeve and wherein a pair of tightening recesses are formed in said outer end portion of said outer sleeve for receiving cooperating parts of a tool whereby said quench tube is threadedly related with said hollow support.

8. A quench tube constituting a component of an electric connector apparatus, said quench tube comprising an inner sleeve of arc extinguishing material, and an outer sleeve of mechanically strong plastic material, said outer sleeve including an end portion at one end which completely overlies the associated end portion of said inner sleeve and said inner sleeve protruding beyond the other end of said outer sleeve.

9. A quench tube according to claim 8 wherein at least one groove is formed about the inner periphery of said quench tube and disposed at the junction between said end portion of said outer sleeve and the associated end of said inner sleeve and wherein a resilient grommet is seated within said groove.

10. A quench tube according to claim 8 wherein a plurality of grooves are formed about the inner periphery of said quench tube and wherein a plurality of resilient grommets are seated within said grooves respectively.

11. A contact pin constituting a component of an electric connector apparatus, said contact pin comprising a tubular pin of conducting material, a stem of mechanically strong plastic material having a cap portion at one end and secured at its: other end to the end of said tubular pin which is subjected to arcing and arranged in coaxial relation therewith, and a hollow tubular sleeve of arc extinguishing material of considerably less mechanical strength than said stem and disposed about said stem and in coaxial relation therewith and having one end in snug engagement with said cap portion of said stem and having the other end in snug engagement with the adjacent end of said tubular pin of material.

EJNITEU STATES PATENT newer:

TEFE'QATE UP CO'RECEIQN PATENT NO. 3 917 374 DATED November 4, 1975 |NVENTOR( Robert E. Murdock It is certified that error appears in the above-identified patent and that said Letters Patent. are hereby corrected as shown below- On the frort page under INID Number [22] the filing date should read August 19, 1974 Signed and Sealed this twenty-third 1y Of March I 9 7 6 [SEAL] A ttest:

RUTH C. MASON Arresting Officer

Claims

1. Electric connector apparatus comprising a tubular contact pin, a tubular contact socket of conducting material having at least one open end arranged to cooperate with said contact pin, and a hollow tubular quench tube disposed at said one end of said contact socket and arranged in substantially aligned coaxial relation therewith so as to accommodate telescopic movement of said contact pin relative to said contact socket and quench tube, said tube being of composite construction and including an inner sleeve of arc extinguishing insulating material and an outer sleeve of mechanically strong plastic material.

11. A contact pin constituting a component of an electric connector apparatus, said contact pin comprising a tubular pin of conducting material, a stem of mechanically strong plastic material having a cap portion at one end and secured at its other end to the end of said tubular pin which is subjected to arcing and arranged in coaxial relation therewith, and a hollow tubular sleeve of arc extinguishing material of considerably less mechanical strength than said stem and disposed about said stem and in coaxial relation therewith and having one end in snug engagement with said cap portion of said stem and having the other end in snug engagement with the adjacent end of said tubular pin of conducting material.

12. A contact pin according to claim 11 wherein said cap portion of said stem is bevelled at the part thereof remote from said hollow sleeve of arc extinguishing material.