US2500474A - Connection actuated receptacle switch - Google Patents

Description

March 14, 1950 J. J. SPERRAZZA. 2,500,474

CONNECTION ACTUATED RECEPTACLE SWITCH Filed Jan. 31, 1947 2 vSheens-Sheer. l

ATTOP/Yt'YS Patented Mar. 14, 1950 gait OFFICE CONNECTION ACTUATED RECEPTACLE SWITCH Jerome J. Sperrazza, Buffalo, N. Y.

Application January 31, 1947, Serial No. 725,455

2 Claims. 1

This invention relates to improvements in electrical connection receptacles and more particularly to electrical wall outlets or receptacles such as those used in buildings to receive the plugs of lighting and appliance fixtures.

The primary object of the present invention is to provide an electrical connection receptacle wherein the safety factor is greatly increased by so constructing the receptacle as to eliminate the hazard of receiving a shock or burn by inserting a foreign object into one of the openings in the receptacle normally receiving 2. prong of the usual electrical plug.

This increased safety factor is attained by so constructing the receptacle that the circuit through its terminals can be closed only by inserting suitably shaped projections, such as the prongs of an outlet plug, in both of the two openings of the receptacle simultaneously. This may be accomplished by having the contacts in the openings of the receptacle normally dead and so arranging the parts that each contact may be made alive only by inserting a, suitable projection or prong in another or the other opening of the receptatcle. With the receptacle so constructed, if one were to insert a pin or wire in one opening of the receptacle and manipulate it so as to move a part or parts located in the opening which may be moved, even so he would not receive a shock as a result of closing the circuit because the movement effected by the wire or pin would only close the electrical connection to the contact in the other opening of the receptacle; it would not close the circuit, and, in particular, would not close the electrical connection to the contact in the opening in which the pin or wire was inserted, with resultant shock to the operator of the pin or wire. Thus, the circuit can be closed at the receptacle only by inserting elements into both of the openings of the receptacle simultaneously and thus manipulating the movable parts located in the two openings simultaneously; in a practical sense, this permits of closing the circuit at the receptacle only by insertin the two prongs of the plug into the two. openings of the receptacle.

A receptacle so constructed as to embody the invention may take many different structural forms, but stated generally, each such form will include movable parts associated with the openings of the receptacle so as to be moved by the entrance of the prongs into the receptacle, and means whereby the movement of the part associated with one of the openings closes a break in a path for electric current to a conducting (Cl. ZOO-51.09)

member located in the other opening of the receptacle, thereby supplying current to a prong entered therein. In this application, I illustrate and describe in detail one structural form in which the invention may be utilized; other structural forms having the same distinctive features and therefore also embodying the, invention are illustrated and described in an application for U. S. patent filed by me on April 13, 1948, and serially numbered 20,632, and in an application for U. S. patent filed by Harvey Hubbellon April 8., 194. 3. and serially numbered 19,682.

In the accompanying drawings forming a. part of this application:

Fig. l is a top plan view of a twin type receptacle embodying the features of the present invention and showing the receptacle mounted in a conventional, electrical wiring box and provided with a conventional cover plate.

Fig. 2 is a side elevational view of the devices shown in Fig. 1.

Fig. 3 is a vertical central sectional view through the'wiring box and cover plate, with the receptacle embodying the present invention 1 shown in elevation.

-' inserted therein.

Fig. '7 is a. vertical sectional view taken on line l'l, Fig. 6.

Fig. 8 is a vertical transverse sectional view taken on line 8--8-, Fig. 6.

Fig. 9 is a fragmentary vertical sectional view taken on line 9-9, Fig. 6.

Fig. 10 is a fragmentary vertical transverse sectional view taken on line lit-4 ll, Fig. 6.

Fig. 11 is a perspective view of one of the cam members adapted to be engaged by a prong, of av p Referring; to Figs. 1 to 4 of the drawings, the improved receptacle of the present invention is shown mounted on the usual sheet metal electrical wiring box it open. on one side and provided with the usual ears H, on opposite ends thereof for attachment to any suitable supporting. surface such as a wall, floor or the like, according to present practice. The receptacle illustrated is of th duplex or twin outlet type having two pairs of outlet openings, although it will be understood that any number of outlets can be provided. This receptacle comprises a body I2 formed of upper and lower sections 53 and i4 connected together to form a unitary structure. The body l2 may be of any suitable rigid electrical non-conductive or insulating material such as the plastics now commonly used for the bodies of conventional receptacles. While the body sections [3 and M can be built up in any desired manner and suitably connected together, they are preferably cast or molded to shape.

The upper section I3 is similar to exterior shape to that of conventional receptacles, since it is provided with a pair of integral bosses l5 and I5 extending outwardly. A conventional cover plate It having the usual openings to receive the bosses is mounted on the receptacle and secured to the body section l3 by a screw I 8. The bosses l5 and are provided respec- Conventional type openings are advantageously used because most conventional plugs have prongs which are substantially rectangular in cross-section, either in the form of a solid bar as indicated by prong 2|, or in the form of a reversely bent contact element (not shown). Special plugs will therefore not be required. However, the outlet openings, if desired, maybe of any other shape in cross-section to receive the prongs of plugs having similar cross-sectional shapes.

Electrical contact means of similar structure are associated with all outlet openings, comprising electrical contact elements 23 and 23' for the outlet openings l9 and I9, respectively, and elements 24 and 2 for the'outlet openings 26 and as shown in Figs. 5 to 7. The element 23, which is illustrative of all, is made of electrically conductive flat strip material and includes a stationary contact part 25 in the opening l9, an offset movable contact part or spring finger 25 extending generally toward the outlet opening [9, and an intermediate part 2! connecting the part 26 at one end with the inner end of the stationary contact part 25. The stationary contact part 25 of element 23 is arranged in the opening l 9 against the outer side thereof so that its inner fiat side is adapted to have a wiping contact with the prong 2| of the plug 22.- The movable contact finger 26 and the curved intermediate part 2! are accommodated in a recess 29 provided in the body section l3, this recess extending upwardly from the bottom flat face of the body section, as shown in Fig. 7. The recess 29 is of greater Width than the contact finger 26 and intermediate part 27, so as to permit the contact finger 26 to move for a purpose hereinafter described. In this connection the contact element 23 is so bent that the contact finger 2B is springy and is normally biased toward the adjacent outlet opening it or against the inner wall of the recess 29, as shown in Fig. 5. The structure and arrangement of the other contact elements are the same as the element 23.

The recess 29 and the others like it in the upper I body section l3 are closed by the lower body section M, which is shown in the form of a flat plate fitting against the bottom face of the upper body section 13 and secured thereto by screws 30, Figs. 4 and 8. A recess 3i is provided in the lower body section M below each outlet opening to accommodate the ends of the plug prongs, as shown in Figs. 7 and 8.

Electric current is supplied to the four contact elements of the receptacle by current supply bars 32 and 32', each of which is bent near its ends, as illustrated by the bar 32, to provide contacts 33 and 33', respectively engageable by the free ends of the movable contact fingers of the contact elements 23 and 24. The members 32 and 32 are mounted in the same manner, for example the bar member 32 is arranged in a recess 34 in section l3, which at one end communicates with the recess 29 and at the other with a similar recess for contact 22. The bar 32 is prevented from moving or shifting in the recess 34 by projections 35 on its upper edge fitting intorecesses 36 provided in the body section I3, as shown in Fig. 9. The bent end 33 of the bar 32 extends into the recess 29 in the upper body section l3 while the bent end 33' extends into a similar recess for the element 24. The current supply member 32 has bent contact ends 38 and 38'. The contact fingers, such as 25, are normally out of contact with the current supply members as shown in Fig. 5.

The current supply bars 32 and 32' are each connected to a terminal plate 39 by an integral connector ill, depending therefrom. The terminal plate 39 extends into a cut-out ll in the lower body section [4, as shown in Figs. 9 and 10. Electrical energy is supplied respectively to bars 32 and 32 by lead wires 42 and 42' connected to the respective plates 39 by terminal screws 43, which extend through holes provided in the terminal plates 39 and which screw into threaded holes provided in the lower body section It, as shown in Figs. 3, 4, 9 and 10. The opposite ends of the lead wires are suitably connected to a main supply line 44 (Figs. 2 and 3).

The'means for moving the free ends of the movable contact fingers into contact with their current supply members, such as the movement of the finger 26 into engagement with the contact end 33 of the supply member 32, comprise cam members of non-conductive material having the structure of the cam member 45 arranged betweenthe movable contact finger 2t and the outlet opening l9", as shown in Figs. 5, 6, 7 and 11. The cam member 45 is shown as being in the form of a block set in a slot or guideway it, provided in the bottom of the upper body section l3, and

' arranged for sliding movement toward and from the opening l9 along with the movable contact finger 25, in a direction extending generally transversely to the finger. The slot or guideway 45 in which the cam member 45 is slidingly arranged opens at its outer end into the recess 29 so that the cam member can project from the slot 45 into the recess 29 to move the finger 26 into engagement with the current sup-ply contact 33, as shown in Fig. 6. At its opposite end, the slot or guideway 36 is enclosed with an end Wall 43 which is in substantially vertical alinement with the adjacent edge wall of the opening l9 so as to place the slot 46 in communication therewith.

The cam member 45, on the. side facing the opening i9, is provided with a cam projection 49 having a cam face or surface 58 facing the opening l9, as best shown in Figs. 6, 7 and 11. The

eacoonrzc part 49, asshownin Fig. 5, normally projects into the opening 19 through the opening provided in the inner Wall 48 of the slot or guideway 46, movement of the cam projection 49 into the opening i9 being limited by the end wall 4% engagin the opposing end face of the cam member 45. The cam member E5 is urged to this normal position by the spring actionof the movable contact finger '26 which engages its outer end face.

The cam member 45 at the opening i9 is actuated by inserting a suitable object such as the prong 21' of the plug "22 into the opening 19' which will displace the cam member from the inoperative position shown in Fig. '5 to the operative position thereof shown in Fig. 6. More particularly, as the prong 2'1 moves into the opening IS, the outer edge of the .inner .end or corner of the prong engages the cam face '50, and as the prong 21' is pushed farther into the opening, the cam member 45 slides in its :slot or guideway 46 until the cam projection 49 is moved out of the opening it. This movement of the cam memr is ainst the urging-or resistance of the spring finger .26, and the free end of this contact :finger 28 is movedagainsttheopposing side of the 1 current supply contact 33, thereby forming a connection through the element '23 to the plug prong H in opening +9.

The cam member 45 is made of non-conductive material, and therefore --no current will be conducted by it from the contact finger -26 to the prong 2|. Furthermore, when this prong 2| is removed from the outlet opening IS the cam member will be moved by the spring contact finger 26, as it disengages the contact 33, from the operative position shown in Fig. 6 to the inoperative position shown in Fig. 5, thereby breaking the circuit to the element 23 and the plug prong 2| in the opening IS.

The contact part 25 and curved intermediate part 2? of the element 23 are held against displacement or shifting in the recess 29 and opening I9 by arranging the contact part 25 against the outer vertical side wall of the opening l9, and by arranging the inner side of the salient part of the curved intermediate part 21 on an abutment 5|, as shown in Figs. 5 and 6. The abutment 5| forms the inner wall of that part of the recess 29 which accommodates the intermediate part 21.

The contact element 23 is therefore constrained against being displaced except for movement of its movable spring contact finger 26 thereof, the abutment 5! serving as a fulcrum for such movement of the contact finger. The contact elements 23', 24 and 24 have the same structure as the element 23 and are arranged in the body section 13 in the same manner, the movable contact finger of the element 23 being operated by a cam member 45', that of element 24 by a cam member 45 and the spring finger of element 24' by a cam member Q5 These fingers respectively engage current supply contacts 38, 33 and 38, and in general it will be seen that the operating means associated with each of the outlet openings are alike, including the cam members.

In the operation of the receptacle, as shown in Figs. 6 and 8, the insertion of the prongs 2| and 28 of the plug 22 in the outlet openings l9 and 19' effects a wiping contact with the contact elements 23 and 23' before the cam members 45 and 45' move the contact fingers of these elements into contact with the live current supply contacts 33 and 38'. By this means and arrangement, arcing in the outlet openings [9 and I9 is prevented. It will also be noted that the prongs 2| and 21' of the plug 2i! must be inserted in the outlet openings 19 and I9 substantially their full length before the contact fingers of elements '23 and 23 are caused to engage the live ends '33 and 38'. Hence the person inserting the plug 22 is protected against'being burned or shocked in case his fingers deliberately or inadvertently touch the prongs of the plug before they have been pushed all the way into the outlet openings.

Furthermore, as illustrated in Fig. 7, a person is not endangered if he inserts a foreign obgiect such as a bobby pin, even though made of conductive material, into one of the outlet openings. Normally the contact parts arranged in the outlet openings, suchas the part 2'5, are dead, but if the foreign object inserted into one of these outlet openings should move the cam membenthis would merely connect the contact element in --t-hev opposite outlet opening to the current supply. The

opening in which the foreign object is inserted, however, remains dead, and therefore a very desirable safety feature is provided. In order to make both openings of a pair alive, a suitable object must be inserted into each opening in such such a way as to displace the cam member as 'sociated therewith and cause the same to move the corresponding contact finger into engagement with the live current supply contact therefor. This action takes place when the prongs of the plug 22 are inserted in a pair of the holes or openings.

Thereceptacle embodying thepresent invention issuitably mounted on the electrical wiring box it! so that its inner or bottom side, as viewed in Fig. 3, is spaced from the bottom of the box I!) to provide space for the lead wires 42 and 42'. This is in accordance with conventional electrical wiring practice. The body i2 of the receptacle is not as deep or thick as some conventional types of receptacles and therefore, if desired, can be mounted on a shallower wiring box i 0 than presently being used for this type of receptacle and still provide the amount of space between the box and receptacle, to accommodate the wiring, as required by present building codes. In this connection, also if desired, the terminal plates 39 of the current supply members 32 and 32' can be provided with one or more additional terminal screws similar to the screws 43 for attachment of additional lead. wires (not shown), such as for running lead wires to another receptacle at a remote point.

While the body [2 may be variously mounted on the electrical wiring box Iii, it is shown as having molded therein a horizontal attaching plate 68 (Figs. 3 and 8) which extends completely through the body l2 and is formed at its ends to provide an attaching gear 6| on opposite ends of the body l2, as shown in Figs. 2, 3, 4 and 8. Each of these ears 66 is provided with an opening to receive an attaching screw 62 :which screws into a threaded hole provided in a mounting ear E3 on the wiring box In.

From the foregoing description it will be seen that the present invention provides a safe electrical connection receptacle in which the outlet openings are normally dead, and that one opening can only be made live by the insertion of a suitable object into another opening, thereby providing protection particularly against injury to children who are prone to insert foreign objects into such receptacles. The improved receptacle is adapted to receive conventional type plugs and therefore does not require a special plug; it can replace conventional types of wall receptacles since it is installed in the same manner; and it is simple, serviceable and inexpensive to manufacture.

I claim:

1. An electrical plug receptacle, comprising a body having two separable parts connected together, a pair of terminals arranged within said body and between said body parts and each adapted to be connected to a source of electrical energy, one of said body parts being provided with a pair of outlet openings arranged between said terminals, an electrical contact part arranged in each of said openings, a, movable contact member for and connected to each of said contact parts and operatively' arranged in opposing relation to one of said terminals and normally disconnected therefrom, and an actuating member of insulating material for and associated with each of said openings and arranged between opposed guide :surfaces of said two body parts for rectilinear .movement and so rectilinearly movable upon the insertion of an object in the corresponding opening to move the movable contact member for'the other outlet opening into contact with its terminal.

2. An electrical plug receptacle, comprising a body having two separable parts connected together, a pair of spaced generally parallel terminal bars arranged within said body between said body parts and each having a terminal intermediate its ends adapted to be connected to a source of electrical energy, one of said body parts being provided with .a pair of outlet openings arranged between each of the corresponding ends of said terminal bars, an electrical contact part arranged in each of said openings, a movable contact member for and connected to each of said contact parts and operatively arranged in opposing relation to one of the adjacent ends of said terminal bars and normally disconnected therefrom, and an actuating member of insulating material for and associated with each of said openings and arranged between opposed guide surfaces of said two body parts for rectilinear movement and so rectilinearly movable upon the insertion of an object in the corresponding opening to move the movable con-' tact member for a difierent outlet opening into; contact with its terminal bar. 1

JEROME J. SPERRAZZA.

REFERENCES CITED 7 The following references are of record in the file of this patent:

UNITED STATES PATENTS

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