US1918071A - Cord terminal - Google Patents

Description

July 11, 1933. V -rs v 1,918,071

I CORD TERMINAL 'Original Filed Feb. 1, 192a FIIE J 5 INVENTOR JVo/e H- VVaif-s Way? A TTORNEYS Patented July 11, 1 933 UNITED STATES PATENT oFFicE NOBLE H. WATTS, F OAKLAND, CALIFORNIA, ASSIGNOR, BY MESN E ASSIGNMENTS, TO GENERAL ELECTRIC COMPANY, OF SCHENECTADY, NEW YORK, A CORPORATION OF NEW YORK CORD TERMINAL Application filed February 1, 1928, Serial No. 251,103. Renewed September 10, 1932.

This invention relates generally to electrical connecting devices suitable for use 5 necting devices.

with flexible electrical cords and which serve to cooperate with complementary con- It relates particularly to male connectors of the bayonet type for insertion in electrical sockets orreceptacles.

In the manufacture of terminal connectors for electrical c0rds,,it has previously been 0 proposed to utilize a body of resilient insulating material such as rubber which is arranged to embed and form a resilient mount.- ing for the contact members. A terminal of this type is disclosed and claimed in my application No. 163,012 filed January 2 1, 1927 and entitled Electrical cord terminal. The various features of the invention described herein are particularly applicable to a resilient terminal of this kind, as will be obvious from the subsequent description.

It is an object of this invention to devise a cord terminal which will withstand relatively high voltages.

It is a further object of this invention to devise an improved form of resilient termi-' nal which is particularly applicable for heavy duty service, that is which will carry heavy currents at relatively high voltages.

It is a further object of this invention to devise a terminal which will have provision for grounding a conductor of an electrical cord with which it is associated.

It is a further object of this invention to devise an electrical terminal which will have provision for piloting the exposed contact members into a socket or receptacle.

It is a further object of this invent on to devise improved means for mounting andsccuring a metallic contact member within a resilient body.-

It is another object of this invention to devise a terminal of the resilient type having an improved arrangement for making electrical connection-between the contact members and the conductors of the cord with which it is employed.

Further objects of this invention will appear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that the appended claims are to be accorded a range of equivalents consistent with the state of the prior art.

Referring to the drawing:

Figure 1 is a side elevatio'nal view partly in cross section illustrating the terminal constructed in accordance with the principles of this invention.

Fig. 2 is an end View of the terminal as shown in Fig. 1. v

Fig. 3 is a cross sectional view taken along the line 33 of Fig. 1.

Fig. 4 is a cross sectional view taken along the line 4-4 of Fig. 1.

Fig. 5 is a cross sectional view illustrating a socket suitable for receiving a terminal such as shown in Figs. 1 to 4.

Fig. 6 is an end view of the socket shown in Fig. 5.

The specific embodiment of the invention which I have illustrated in the drawing comprises a plurality of metallic contact mem-.v bers 11 which are formed in accordance With the character of the complementary connector with which the terminal is adapted to be used. As certain features of the invention are especially desirable in a bayonet type of male connector, I have shown the members 11 as being in the form of metal strips of high electrical conductivity. For mounting the contacts 11 I provide a body 12 which is preferably made of some resilient insulating material, such as vulcanized rubber. The cont-acts 11 are embedded in the material of the body 12 so as notonly to afford high electrical dielectric strength between the inner ends of the con-- tacts 11, but also to provide a certain properties of the resilient insulating material of the body 12 will prevent arcing between the contacts 11 within the body, and consequently if any arcing at all will occur when used with high potentials it will take place between the contacts along the leak path formed by the face 13 of the body. In order to render a terminal of a given size effective for use with higher voltages, I minimize the tendency for arcing between the contacts 11, by providing bosses 14 of substantial height surrounding the exposed portions of contacts 11 as shown. These bosses are made of resilient insulating material, and are joined with the material of the body 12 to form an integral structure. In the manufacture of my terminal I preferably form both body 12 and bosses 14 of rubber which is vulcanized about the contacts to form a homogenous whole. Direct arcing between the portions of the contacts surrounded b the bosses 14 is therefore prevented, an because of the height of the bosses the surface distance between adjacent contacts is substantially increased. The resilient character of the bosses 14 in combination with a terminal having a resilient body, is a feature of importance since it minimizes the possibility of mechanically cracking or breaking of the bosses with resulting decrease in the break down voltage which the terminal is able to withstand.

While the body 12 may be applied to a variety of electrical cords, I preferably utilize a cord 16 in which the electrical c011- ductors 17 are enclosed within a sheath 18 of vulcanized rubber or other suitable resilient insulating material. Instead of merely embedding the inner ends of contacts 11 within the body 12, I preferably anchor themdirectly to the end of the sheath 18 and then apply the body 12 about the contacts 11 and the end of the sheath, so that the sheath and body are merged as an integral structure. Thus the inner end 19 of contacts 11 are. preferably clamped upon the end portion of casing 18 as by means of a number of turns of cordor binding tape 21.

To enable the ends 19 to more closely fit the periphery of sheath 18, they are preferably bent arcuate in shape as shown in Fig. 4. The tape 21 is preferably wrapped fairly tightly about the end portion 19 so as to press the same down onto the resilient sheath 18, thus securely anchoring the con tacts 11 to the sheath.

In order to provide electrical connection between the conductors of the cord and the contacts 11, these conductors,--if they have individual insulation,-are bared where they project from the endof the sheath and are turned back and extended as indicated at 22, between the end portions 19 and the periphery of sheath 18. Where each conductor merges from the end of contact portion between contact member 26 and both alternating and direct current work to utilize an extra conductor 24 in the cord 16, to serve as a protective grounding conductor. The terminal for this cord is preferably provided with an extra contact member connected with the grounding conductor. Thus I have shown an extra contact member 26 which is preferably arranged symmetrical or centrallywith respect to the contacts 11, and which is likewise mounted upon the resilient body 12. For anchoring this member 26 within the body I have shown a member 27 in the form of a metal plate which extends substantially parallel to the face 13 of the terminal, and member 26 is suitably secured to this plate as by means of the rivet connection 28. A plu-- rality of apertures 25 are preferably provided in plate 27 in order to secure more effective anchoring to the resilient body. The metal'plate 27 is out of direct physical contact with the contact members 11, and forthis reason I have shown in Fig. 3 a plate triangularly shaped to provide a substantial amountof insulation between the same and the adjacent portions of the contact members 11.

The end of the grounding conductor 24 projecting from the embedded end of sheath '18, is electrically connected to member 27 as by'means of the soldered connect on 29. It is to be noted that conductor 24 15 provided with a lateral extending portion 31 before making electrical connection with plate 27 This expedient permits a certain amount of movement of plate 27 in response -ments of member 26 permitted by the resilient character of body 12 might break loose the soldered connection. Likewise the looping of the conductors 17 where they are bent back beneath the inner portions 19 of contacts 11, prevents any direct strain from be ing placed upon these conductors and their soldered connections. Contacts 11 and members 26 are thus free to move a limited amount and the plug may be repeatedly removed from a socket by pulling upon the cord, without endangering the electrical connections to the conductors.

In order to minimize the tendency to are contact the face of the receptacle, and this face is members 11, member 26 is preferably pro-- .first stripped back from its end to expose a length of each conductor, and these conductors are then stripped of their individual insulation if any. The portions of contact members 11 which are to be exposed are then secured to a suitable clamping device and the portions to be embedded are pressed down about the end of sheath 18 over the turned back portions 22 of the conductors. The soldered connection 23 is then made and the tape 21 or cord applied to securely press the ends of the contact members into the resilient sheath 18, thus anchoring the contact members to the cords. Unvulcanized rubber, such as for example is used in the manufacture of rubber tires, is then applied to the structure to form the body 12. This rubber may be applied in the form of a ribbon or in any other form which will facilitate manufacture. The structure is then placed within a suitable mold and properly heat vulcanized to form a bond between the body 12 and the resilient sheath 18, and to eventually embed themembers 11 and 26,- and the anchoring plate 27. -By making metallic members 11 and 26 outof proper material such as brass, an effective bond may be maintained between the embedded portions and the rubber. The body is preferably provided with a tapered portion 33 of reduced diameter where it merges with the sheath 18, in order to prevent sharp bending of the cord where it enters the body.

A suitable socket or receptacle for receiving a terminal such as described above,

is shown in Fig. 5. This socket may be briefly described as comprising a body member 34 of insulatingmaterial within which is retainedthe freefioating' spring contact members 36. Another central contact member 37 may be provided for receiving the central member 26 of the the terminal. Contacts'36 and 37 are preferably set in from provided with openings 38 and 39 of sufiicient size to receive the bosses Hand 30. As shown in Fig. 1 I prefer to make the exposed portion 'of'member 26 longer than the exposed portions of contact 1150 that members 26 may be employed as a pilot" member to aid in introducing the terminal contact into the receptacle. Thus since the end ofmember 26 is first introduced into the opening 39, it serves as a means for centering the terminal with respect to the receptacle and therefore aids in properly centering contacts 11 with respect to the contacts 36 of the receptacle. When used with three phase systems, the terminal need not be polarized with respect to the socket or receptacle and therefore any one of the Gil three receptacle contactsmay be engaged by a particular contact 11. It is therefore a simple matter to insert such a terminal into a socket, since the terminal need never be rotated more than 120 to bring the contacts into alinement.

I claim: i

1. In a cord terminal, a plurality of metallic contact members, a cord having a plurality of electrical conductors encased in a sheath of flexible insulating material, means for clamping adjacent ends of said contacts to one end of said cord sheath, the conductors projecting from said end of the sheath being turned back along the periphery of the sheath between the contact members and said sheath and being electrically connected with said members, and a body of insulating material embedding portions of said contact members and said end of the sheath.

2. Ina cord terminal, a body of resilient insulating material, three spaced contact members embedded in said body, a substantially triangular metallic plate embed- .ded in said body between said members and insulated therefrom, and a fourth contact member secured to said plate.

' 3. A terminal for a flexible cord comprising a plurality of electrical contacts, a

ground contact provided with an anchoring means disposed intermediate said electrical contacts, an end of a resilient sheathed cord having a pluralityof bared electrical conductors and a ground wire extending from y the end thereof, being interposed between said electrical contacts, said electrical conintermediate the contacts and cord sheathing, means binding said contacts to said cord sheathing, said ground wire being connected to said ground contact, and a resilient ductors being bent backward and disposed In testimony whereoflI have hereunto' set my hand.

NOBLE H. WATTS.

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