US2105884A - Plug contact - Google Patents

Description

Jan. 18, 1938. c. A. HANSER ET AL 2,105,884

PLUG CONTACT Filed June 22, 1936 11v VENTORS CHARLES HANSER BY munsucmgg A TTORNE YS Patented Jan. 18, 19 38 4 UNITED STATES PATENT OFFICE PLUG CONTACT Charles A. lianser, Detroit, and Laurence H. Thomas, Birmingham, Mich, assignors to American Electrical Heater Company, Detroit, Mich., a corporation of Michigan Applicationlune 22, 1936, Serial No. 86,684

3 Claims. (Cl. 173-332) The invention relates to electrical contact mem- Figure 3, A is the insulator casing or plug atbers, such as are used in plug contacts for flexible tached to the flexible electrical conductor B, and conductors and has more particular reference C is our improved contact member located within to constructions designed for use with electrically a recess D in said plug. .This contact is formed 5 heated devices, such as laundry irons. It is usual of a strip of metal of relatively high electrical 5 to form plug contact members of a bronze having conductivity such as a copper alloy. This strip desirable qualities, such as high electrical conis bent at E into U-shaped form with its end ductivity, low coefilcient of friction and the oxide portions return-bent at F and F to extend within of which isalso an electrical conductor. This the U in normal contact with each other. The

material when first formed has sufflcient-inherent electrical conductor is attached to the contact by 10 resiliency to firmly press against the cooperating a clamping screw G which extends through the contact so as to insure good electrical connection. portion adjacent to the bend E and having a When, however, such contacts are used in conthreaded engagement therewith. nection with electrical heaters, heat transmitted With the construction as thus far described,

thereto will generally draw the temper of the when the plug is engaged with cooperating terll metal so that it loses its resiliency. Consequentminal contacts H such as on a laundry iron, these ly, the electrical connection will be imperfect contacts will be inserted between the return-bent causing arcing and further heating with'destrucportions separating the same while the resiliency tive efiect. There are certain metals, such for of the metal will maintain a contact. However,

an instance as stainless steel or Monel" metal that if this resiliency is destroyed by heating, then the will retain their resiliency even when heated to furcations of the contact will remain permanently a considerable extent. However, these metals spaced from each other so as to not make good are not well adapted for electrical contacts for contact with the member H. This difliculty is various reasons. Thus, Monel" metal when overcome by arranging within the U-shaped porheated forms a coating of oxide of an electrical tion a resilient member formed of metal which 5 insulating nature. On the other hand, stainless will retain its resiliency under any heat to which steel when heated has an excessively high coefliit may be subjected. For this purpose, we prefcient of friction so as to interfere with the inerably use either a stainless steel or Monel sertion or withdrawal of the cooperating contact. metal. As above stated, neither of these are It is the object of the present invention to obsuitable for forming the contact members, but 30 tain a construction of resilient electrical contact are used as springs for pressing the contact porwhich will retain its resiliency when heated as tions of the member C against the cooperating well as having other desirable qualities. To this contact. Thus, as specifically shown I is a U- end the invention consists in the construction as shaped member formed of either of the above hereinafter set forth. mentioned metals or any other resilient material 35 In the drawing: which will maintain its resiliency when subjected Figure 1 is an enlarged longitudinal section to heat. This member I-' is arranged within the through our improved contact; U of the member C andhas its outer ends bent Figure 2 is a perspective view thereof; inward to bear upon the return-bent portions F 40 Figure 3 is a section showing the device in use and F and to press them against each other. 40 in connection with a laundry iron; The member I is held in place preferably by Figure 4 is a section through the plug at right punch rivets J connecting it with one side of the angles to Figure 3; member C, while at the opposite side it is bulged Figure 5 is a section on line 55 of Figure 2. outward to bear against the adjacent side of the As specifically shown, the resilient contact member C and thus when the cooperating con- 45 member is one designed for use in a plug for the tact H is inserted between the return-bent porconductor cord of a laundry iron. It is usual tions F and F, the spreading of these portions to place such contact members in recesses in a is resisted by the tension of the member I which plug which latter is formed of insulating madevelops suillcient pressure to insure good electerial thereby avoiding any danger of short-cirtrical connection. 50 cuiting. The contacts are also bifurcated to em- As has been stated, it is necessary to anchor brace the cooperating contact member and are the contact within the plug A so as to resist the anchored within an insulator plug or casing so thrust and pull of attaching or disengaging the as to resist the thrust and pull incident to enplug. This anchor connection should have suiligaging or disengaging the plug. As shown in cient rigidity to take care of such stresses and 55 threaded socket or nut for the screw. The flanges of the member K are provided with angle-bent portions K for engaging pockets in the plug A to 10111 the member from displacement. Thus the member K is fixed in position within the plug or casing A and is rigidly secured by the screw G to the member C.

What we claim as our invention is:

1. An electrical contact comprising a U-shaped strip of metal having its end portions inwardly return-bent, said-strip being formed of flexible material having good electrical conductivity, a low coefficient of friction at high temperatures and the oxide of which is a relatively good conductor, and a resilient reinforcing member arranged within the U and embracing the returnbent portions thereof, said reinforcing member being formedof material which retains its resil- 25 iency when subjected to heat.

2. An electrical contact comprising a flexible strip of metal having good electrical conductivity,

a low coemcient of friction at high temperatures and the oxide of which is a relatively good conductor, said strip being bent into U-shaped form with the end portions inwardly retum-bent to normally contact with each other and a U-shaped resilient reinforcement arranged within the U of said first mentioned member and embracing the return-bent portion thereof, 'said ireinforcing member being formed of metal which retains its resiliency under heat.

3. An electrical contact comprising a strip of metal having good electrical conductivity, a low coefflcient of friction at high temperatures and the oxide of which is a relatively good conductor, said strip being bent into U-shaped form with the end portions inwardly retum-bent to normally contact with each other a U-shaped resilient reinforcement arranged within the U of said first mentioned member and embracing the returnbent portion thereof, said reinforcing member being formed of metal which retains its resiliency under heat, an insulator casing enclosing said members, and an anchor for said members within said casing formed of metal which retains its rigidity when subjected to heat.

CHARLES A. HANSER.

LAURENCE H. THOMAS.

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