US2705309A - Electric plug - Google Patents

Description

C. BRAMMING ELECTRIC PLUG March 29, 1955 Filed Sept. 9, 1952 IN V EN TOR.

IIIIIIIIIIII ivi United States Patent ELECTRIC PLUG Carl Bramming, Nashville, Tenn., assignor to Aladdin Industries, Incorporated, Nashville, Tenn., a corporation of Illinois Application September 9, 1952, Serial No. 308,584

2 Claims. (Cl. 339-105) This invention relates to connector plugs used in establishing electrical connections, and is here described par ticnlarly with reference to the plugs used on low-demand electrical devices such as lamps, clocks and radios, although the principle of the invention may be employed in plugs used with heavier equipment.

Electric connector plugs, and the conductors associated with them are subject to a great deal of mishandling and abuse, and consequently get out of order frequently. The most common abuse occurs when a person pulls the plug out of the wall socket by grasping the wire rather than the body of the plug. Upon repeated pulling of the wire, the connection at the usual terminal clip and binding screw is broken, and the plug must be disassembled and a new connection made.

This abuse is particularly prevalent with the newer smaller types of plug which have come into extensive use. The smaller plug invites its removal by pulling on the wire becauseit presents no convenient gripping surface on the body thereof.

Another form of abuse requiring replacement of electrical connector plugs arises from their being crushed by pieces of furniture or by being stepped upon.

The replacement of electric connector plugs of the usual type is ahousehold chore not often enjoyably anticipated. The mechanic must equip himself with a screw driver, some means for stripping insulation from the wire, such as a knife, and possibly a pair of wire cutters or pliers. Carejmust be used in connecting the wires to insure a proper grip and to obviate any short-circuiting. The discardedxwire and particles of insulation material must be cleaned up and disposed of after the connection has been reestablished or the plug has been successfully replaced.

It is therefore an object of this invention to provide an electric p ug with which a wire may be operativel-y assembled without the use of tools. :1,

A further object is to provide a plug which grips the wire in such a manner as to permit repeated removal of the plug from a wall socket by pulling on the wire without breaking the connection between the plug and the wire.

A still further object is to provide a plug having a body formed of two substantially identical molded halves, the halves being capable of being molded in the same cavity, their non-identical feature being provided by a choice of diiferent pre-formed metal members which are cast into the respective body halves.

Further objects and advantages of this invention will be apparent from a consideration of the following specification together with the accompanying drawings, in which,

Fig. 1 is a view in side elevation of an electric plug constructed according to this invention, with the usual lamp cord conductor being shown in operative position,

Fig. 2 is a view in end elevation of the plug of Fig. l,

Fig. 3 is an exploded view of the plug of Fig. l, with the parts in their disassembled condition,

Fig. 4 is a top plan view of the clamping ring in its unstressed condition,

Fig. 5 is a view in vertical section of one-half of the body of the plug on the line 55 of Fig. 2, and

Fig. 6 is a lower plan view of the plug of Fig. l.

The plug 10 is formed of two mating halves 11 and 12, and is held in its assembled condition by the clamping ring 13. The mating halves 11 and 12 are identical ex- 2,705,309 Patented Mar. 29, 1955 ceplt 1for differences provided by the contact blades 14 an 5.

The plug halves 11 and 12 are preferably formed of a molded non-conducting plastic material. They have a lower oval-shaped body portion 16 and an upper tapered portion 17, the portion 17 being larger at its lower edge than is the portion 16, thereby providing a shoulder 18. As shown particularly in Figs. 2 and 6, the shoulder 18 may be formed as a substantial projection beyond the clamping ring 13, thereby providing a gripping surface for use in removing the plug 10 from a wall socket.

The meeting faces 19 are each provided with a symmetrically oifset tongue 20 and a correspondingly offset socket 21, into which the opposite tongue 20 is receivable for aligning the parts and assisting in holding them together. A channel 22 is provided between the tongue 20 and the socket 21 to receive the two-wire conductor 23 which is shown as the non-twisted parallel wire type. At the lower end of the channel 22, and in communication therewith, the cavity 24 is defined to receive the folded end 25 of the conductor 23.

The contact blade 14, in the body half 11 has the usual straight shank 26 having the aperture 27. The blade 14 terminates, at its upper end, in a sharp prong 28 projecting at a right angle from the shank 26 and extending through the wall of the channel 22, offset toward the tongue 20, for engagement with one wire in the conductor 23, in which, as shown in Fig. 3, it has made the hole 29. Being thus offset, and of a length sufficient to extend to the back of the opposite channel 22, the prong 28 will establish electrical contact with the wire in one half of the conductor 23, without engaging the wire in the other half of the conductor 23.

The contact blade 15 is identical to the contact blade 14, excepting that its shank 30 is slightly shorter than the shank 26 of the contact blade 14. Since the lower ends of the shanks 26 and 30 extend an equal distance from the body halves 11 and 12, the sharp prong 31 of the blade 15 is situated slightly below the prong 28, as is apparent from the position of the hole 32 relative to the hole 29. It has been found that a difference in length of the blades 14 and 15in the order of one-eighth of an inch is ample for safety.

In the molding of the body halves 11 and 12, the apertured end of contact blade 14 or 15 is held outside the mold cavity during the molding operation. Since the blades 14 and 15 project a uniform distance from the bottom of the plug 10, it is possible to mold both body halves in the same cavity.

To assemble the parts of the plug 10 from the position shown in Fig. 3, the folded end 25 of the conductor 23 may be placed in the cavity 24 in the body half 12. The body half 11 is placed next to the half 12, the respective tongues 20 are inserted into the sockets 21 and the whole is tightly held while the clamping ring 13 is assembled over the lower portions 16 and pushed up to the shoulder 18. The sharp prongs 28 and 31 will cut the respective holes 29 and 32, thereby making the required contact with the conductors.

The clamping ring 13 is resilient, and, in its unstressed condition as shown in Fig. 4, is slightly bowed at its respective sides. When the ring 13 is placed over the portions 16, it is forced into the shape shown in dotted outline in Fig. 4, thereby tightly clamping the respective halves together.

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

1. An electrical connector plug for use with an appliance cord having a pair of conductors covered with insulation, said plug comprising an insulating body including a pair of complementary body members having mating surfaces, a pair of contact blades mounted in said body, said blades having sharply pointed elements at their inner end for piercing the insulation on the cord and contacting the respective conductors thereof, said body members having opposed channel elements formed in said mating surfaces and defining a channel for admitting the cord to said body, said channel being of a size corresponding to a single thickness of the appliance cord, said sharply pointed elements of said blades projecting 3 into said channel to pierce the cord, said body member having opposed cavity elements defining a cavity cornmunicating withthe inner end of said channel,'said cavity" being of a size corresponding to at least a double thickness of the appliance cord, the inner end of the cord being folded over in, said cavity when in position of useto retain the cord in said body.

' 2. An electrical connector, comprising an insulating body including a pair of complementary body members a size corresponding to a single thickness of said appliance cord, said cord being snugly received in said channel, said sharply pointed elements of said blades projecting into said channel and piercing said insulation to contact said respective conductors, said body members having opposed cavity elements defining a cavity communicating With the'inner end of said channel, said cavity being of a size corresponding to at least a double thickness of said appliance cord, the inner end of said cord being folded over upon itself in said cavity to retain said cord in said body.

References Cited in the file of this patent UNITED STATES PATENTS 1,324,994 Benjamin Dec. 16, 1919 2,158,922 Barnitz May 16, 1939 2,229,403 Benander Jan. 21, 1941 2,502,860 Leithiser Apr. 4, 1950 2,609,415 Benander Sept. 2, 1952 2,658,184 Greenbaum Nov. 3, 1953 FOREIGN PATENTS 266,976 Switzerland May 16, 1950

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