US3656089A

US3656089A - Electrical plug

Info

Publication number: US3656089A
Application number: US43021A
Authority: US
Inventors: James R Bailey
Original assignee: Switchcraft Inc
Current assignee: Switchcraft Inc
Priority date: 1970-06-03
Filing date: 1970-06-03
Publication date: 1972-04-11
Anticipated expiration: 1989-04-11
Also published as: CA929627A

Abstract

An electrical plug useful as a telephone plug and for other purposes is constructed with a removable handle which is interlocked with the plug body and can be removed to expose one or more terminals within the plug merely by rotating the handle a partial turn in one direction and pulling the two members apart axially. The handle and plug body can then be reassembled and interlocked by rotating the handle a partial turn in the opposite direction. Assembly screws are thereby eliminated.

Description

United States Patent [15] 3,656,989 [4 1 Apr. 11,1972

Bailey [54] ELECTRICAL PLUG [72] Inventor: James R. Bailey, Chicago, Ill.

[73] Assignee: Switchcraft, Inc., Chicago, Ill.

[22] Filed: June 3, 1970 [21] Appl. No.: 43,021

[52] 1.1.8. Cl. ..339/110 C, 339/183 [51] lnt.Cl ..H0lr 17/18, HOlr 13/62 [58] FieldofSear-ch ..339/88,108,110,182,183, 339/213 [56] References Cited UNITED STATES PATENTS 1,365,851 1/1921 Reynolds ..287/58 1,302,471 4/1919 Richter... ..339/183 Morrell ..339/ 108 T? Primary Examiner-Marvin A. Champion Assistant ExaminerLawrence J. Staab Attorney-Johnston, Root, OKeeffe, Keil, Thompson and Shurtleff' the opposite direction. Assembly screws are thereby eliminated.

6 Claims, 10 Drawing Figures 1/195 6 Kimble ..339/108 TP PATENTEDAPRH I972 3,656,089

JAMES R. BAILEY BY gvh za m (57% l BACKGROUND or THE INVENTION Conventional electrical telephone plugs normally consist of an elongated plug body, one end of which is adapted to be inserted into an electrical jack. The plug body is normally tubular and contains a cavity for one or two electrical terminals depending upon whether the plug is a two-conductor or a threeconductor plug. The portion of the plug body containing the electrical terminal or terminals is usually covered by a tubular handle which is held in place by means of a screw. The handle can be removed by removing the screw thereby exposing the electrical terminal or terminals. This type of plug suffers from the disadvantage that it is sometimes difficult to replace the screw used in assembling the handle with the plug. In small plugs the screw is small, and it has to be aligned with the threaded portion of the plug body which is sometimes quite difficult. Very often the screw becomes displaced and frequently is lost during attempts to assemble the handle with the plug body.

OBJECTS ing it over the plug body and rotating it a partial turn.

A more specific object of the invention is to provide an electrical plug of the type described having a simple and positive interlocking means between the plug and the handle which permits the removal of the handle and its reassembly with the plug without the use of screws.

Other objects and advantages of the invention will be apparent by reference to the following description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A illustrates the first step in removing the handle from the plug;

FIG. 18 illustrates the second step in removing the handle from the plug;

F IG.2 is a perspective view of the handle with parts broken away;

FIG.3 a cross sectional viewof the handle taken along the line 3-3 of FIG. 2;

FIG. 4 is a vertical sectional view of the plug body of a twoconductor plug showing the handle in phantom;

FIG. 5 is a partial vertical sectional view of the plug body of a three-conductor plug;

FIG. 6A is a plan view of a portion of the plug shown in FIG.

FIG 6B is an end view of the portion of the plug shown in FIG. 6A;

FIG. 7 is an enlarged sectional view taken along the line 7 7 of FIG. 6A showing the interlocking mechanism in the interlocked position; and

FIG. 8 is the same as FIG. 7 except that it shows the interlocking mechanism in the locked position.

BRIEF SUMMARY OF THE INVENTION In accordance with the invention an electrical plug is provided having an elongated plug body, one end of which is adapted to be inserted into an electrical jack, said plug body containing at least one electrical terminal, a removable handle covering said portion of said plug body containing said terminal, and mechanical interlocking means between said handle and said plug body adapted to lock said handle in fixed relationship with said plug body upon rotation of said handle a partial turn in one direction, and to permit unlocking and removal of said handle from the portion of said plug body containing said tenninal upon rotation a partial turn in the opposite direction.

DETAILED DESCRIPTION OF TI-IE INVENTION Referring to FIG. 4 of the drawings, a two-conductor electrical plug is illustrated which consists of a plug body generally shown at l and a handle generally shown at 2 (see also FIGS. 2 and 3). One end of the plug body has a tip rod 3 and a sleeve 4 usually made of brass or other electrically conducting material and insulated from one another by an insulating material 5 usually made of ethyl cellulose, nylon, or other electrically insulating material which can be molded. The tip rod and sleeve are normally round in cross section and are adapted to be inserted into an electrical jack. The sleeve 4 has a laterally extending offset portion 6 which extends rearwardly to form a generally tubular housing 7 adapted to receive an electrical conductor 8 which is connected to the inner portion 9 of the tip rod 3 by means of a screw 10; As shown, the housing 7 has an opening in the wall thereof at 11, so that when the handle 2 is removed the screw 10 which connects the conductor 8 to the inner end 9 of tip rod 3 is readily accessible.

The rear end 12 of the plug body I is provided with internal threads 13 so that a cable 14 having an electrical conducting shield 15 can be inserted into the opening of the rear end of the plug body thereby electrically connecting the shield 15 to the sleeve 4 through the housing 7.

The electrical plug illustrated in FIG. 5 is similar to the plug illustrated in FIG. 4 except that'it is a three-conductor plug rather than a two-conductor plug. This plug has a tip rod 16, a ring 17 and a sleeve 18, the tip rod 16 being connected to terminal l9 and the ring 17 being connected to terminal 20. The sleeve 18 is electrically connected to the shield of a cable, not shown, in a similar manner to that described with respect to FIG. 4. The shield of the cable is adapted to be held in place by the internal threads 21. I

The tubular handle 2 shown in FIGS. 2 and 3 has an internal boss 22, the forward end 23 of which is spaced inwardly from the forward end 24 of the handle and mates with a groove 25 in the offset portion 6 of the elongated body 1. The insulation 5 which surrounds the tip rod 3 has an inner area 26 which is cut away at 27 to form a recess and at 28 to form a flat surface, the surface 28 being connected to the upper part of the recess 27 by an area 29 as shown in more detail in FIG. 7. The recessed surface 27 is spaced inwardly from the offset portion 6 a distance substantially corresponding to the distance between the end 23 of th'e'boss 22 and the forward end 24 of handle 2 so that when the handle 2 is mounted on the body 1 it can be rotated from the position shown in FIG. 7 to the position shown in FIG. 8 thereby causing boss 22 to ride over the cam surface 28 and the wall 29 to the locked position shown in FIG. 8 in which the boss 22 is seated in the recess 27. To assist in turning or rotating the handle 2 knurled

areas

30 and 31 are provided as shown in FIGS. 2 and 3. Also it should be noted that the handle 2 is usually made of a slightly flexible polymeric plastic material so that it is resilient when pressed thereby facilitating the locking and unlocking of the handle.

MODE OF OPERATION Starting from the locked position shown in FIG. 8 with the handle 2 locked in position on the plug body 1, the handle is removed by grasping the

knurled portions

30,31 with one hand as generally indicated in FIG. 1A, squeezing it lightly and twisting or turning 30 counterclockwise. This causes the boss 22 to disengage from the recess 27 and ride over the wall 29 to the flat portion 28. The boss 22 is then in the unlocked position shown in FIG. 7 and is opposite the groove 25 so that the handle 2 can now be pulled longitudinally and slidably removed over the sleeve 4 and tip rod 3 thereby exposing the area 11 (FIG. 4) and permitting easy access to the terminal screw 10 (FIG. 4) or the terminal screw 19 and 20 (FIG. 5).

The conductor or wire can then be connected to the terminal and the handle can be replaced by aligning the boss 22 with the groove 25 moving the handle axially until it occupies the position shown in FIG. 4, then squeezing the

knurled portion

30,31 slightly and turning it clockwise about until the boss 22 is seated in recess 27 as shown in FIG. 8, thereby locking the handle in fixed relationship to the plug body 1. When the handle is replaced on the plug body, the distance that it can move inwardly is limited by the end 32 of the boss 22 which strikes against the housing of the plug body at the rear end 33 of the terminal cavity 11.

The invention is especially useful in making miniaturized electrical plugs which can be connected to electrical cords in a very simple manner. These plugs are exceptionally light, small and rugged. They contain no assembly screws which have to be aligned and are likely to become lost. The plugs are adaptable either to the two-conductor or three-conductor types. They can be used with shielded replacement cords. The finished plug has complete continuity of thennoplastic insulation and the internal interlock of all parts prevents shifting and shorting under even extreme, rugged usage. These plugs, therefore, are especially useful as telephone plugs, as well as for other applications where plugs are normally used including military equipment, television and broadcast equipment, ground support equipment or any other control panel application where reliability is a primary requirement.

lclaim:

1. An electrical plug having an elongated plug body one end of which is adapted to be inserted into an electrical jack, said plug body having a cavity containing at least one electrical terminal, said cavity having a forward wall adjacent said end and a rear wall, a removable handle slidable axially and rotatable on said plug body and when mounted on said plug body covering said portion of said plug body containing said terminal including said cavity and said forward and rear walls, and mechanical interlocking means between said handle and said plug body adapted to lock said handle in fixed relationship with said plug body when said handle is mounted on said plug body and rotated a partial turn in one direction and to permit unlocking and slidable axial removal of said handle over said end from the portion of said plug body containing said terminal upon rotation a partial turn in the opposite direction, said forward wall containing a peripheral groove extending axially and said handle containing internal boss means adapted to move axially through said groove when said handle is slidably mounted axially over said portion of said plug body containing said terminal and to abut against the rear wall of said cavity so as to limit the inward movement of said handle.

2. A plug as claimed in claim 1 in which said handle is tubular and the portion of said plug body containing said peripheral groove contains a recess adjacent the periphery spaced from said groove, and said handle in the forward portion thereof contains internal boss means seating in said recess when said plug body and handle are interlocked and capable of sliding axially in said groove when rotated to the unlocked position.

3. A plug as claimed in claim 1 in which said handle is slightly resilient and is made of electrically insulative polymeric plastic material.

4. A plug as claimed in claim 1 in which the forward end of said handle has a knurled area on its outer surface.

5. An electrical plug having an elongated plug body including an electrically conducting tip rod and sleeve electrically insulated from one another at one end, extending axially from an intermediate laterally extending offset portion and adapted to be inserted into an electrical jack, said offset portion extending rearwardly to form a generally tubular housing adapted to receive connecting means for connecting said tip rod to an electrical conductor, said housing being formed with an opening in a wall thereof through which said connecting means is accessible, a tubular handle slidably and rotatably mounted on said housing, and interlocking means between said handle and said housing including means to hold said handle in place and prevent axial movement thereof when said handle is rotated in one direction, means to release said handle and permit axial removal thereof over said tip rod and sleeve so as to expose said connecting means in said housing when said handle is rotated in the opposite direction, and internal boss mean spaced inwardly from the rear of said handle adapted to contact the rear side of said opening to limit the inward movement of said handle when it is mounted on said housing and moved axially inward over said opening.

6. An electrical plug having an elongated plug body including an electrically conducting tip rod and sleeve electrically insulated from one another at one end, extending axially from an intermediate laterally extending offset portion and adapted to be inserted into an electrical jack, said offset portion extending rearwardly to form a generally tubular housing adapted to receive electrical conductors to be connected to said tip rod and sleeve, said housing having an opening in a wall thereof extending longitudinally from front to rear, connecting means for connecting said tip rod to one of said conductors in said housing and accessible through said opening, an electrically insulating tubular handle slidable axially and rotatably mounted on said housing, a peripheral groove extending axially in said offset portion, boss means on the inside of said handle spaced inwardly from the forward and rear portions of said handle and adapted to pass through said groove when said handle is mounted on said housing, said boss means at the rear portion of said handle being adapted to abut against the rear side of said opening to limit the inward movement of said handle, a recesses surface in said housing spaced inwardly from said offset portion and adapted to receive said boss means at the forward part of said handle when said handle is rotated whereby when said handle is rotated in one direction said boss means seats in said recess and forms an interlock holding said handle and housing together in fixed relationship and when rotated in the opposite direction until said boss means is opposite said groove said handle can be pulled longitudinally and slidably removed over said sleeve and tip rod thereby exposing said opening in said housing and rendering said connecting means accessible.

*gg ggg Q I 1 I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3,656,089 Dated April 11, 1972 Inventofls) James R. Bailey It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 75, "siciiewf second occurrence should-read screws 1 q v e .1 1 7 Column 4, "line 23, claim 5, "mean" should read means line L 6, claim 6, fteoesses" should read recessed Signed and sealed this 111th day of November 1972.

(SEAL) Attest:

EDWARD M.'FLET0HER,JR. ROBERT GOTTSCHALK Attesting Officer 1 Commissioner of Patents