Electrical receptacle with safety shutter

Oct. 31, 1950 i. moses, jr., et al 2,528,014

ELECTRICAL RECEPTACLE WITH SAFETY SHUTTER

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Filed July 31, 1948

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INVENTORS.

ISAAC MOSES JR. SHAHADY E5A ALBERT. BY

ATTORNEYS.

Patented Oct. 31, 1950

2,528,014

UNITED STATES PATENT OFFICE

2,528,014

ELECTRICAL RECEPTACLE WITH SAFETY SHUTTER

Isaac Moses, Jr., and Shahady Esa Albert, New Kensington, Pa.

Application July 31,1948, Serial No. 41,875

Claims. (CI. 173—330)

Our invention relates to electric receptacles such as are installed in walls, baseboards, etc., and which serve as means whereby an electric appliance may be connected by a cord and plug to live wires and more particularly to what is 5 known as a safety receptacle in which' it is difficult or impossible to make accidental contact with the live parts of the receptacle.

The electric receptacle made according to our invention is adapted to receive any standard 10 plug, or it may be constructed, if so desired, to receive any special plug. The arrangement is such that a shutter or barrier is positioned so that it is impossible to reach the live contacts until the two prongs of the plug are inserted 15 into the prong slots and the shutter then moved so that the plug prongs may be slid further into the receptacle to contact engaging position. When the plug is withdrawn, the shutter member will return to barrier position and prevent 20 engagement with the contacts by means of a foreign single piece of conducting material such as a wire or hairpin which may be inserted into the ordinary receptacle to engage a live contact, and which may cause grave results. 25

Our invention provides two locks for the shutter when in barrier position, which locks must be both released simultaneously to enable the shutter to be moved from the barrier position, which is such that it is impossible to move the-30 prongs of a plug into engagement with the live contacts of the receptacle, to a position whereby the live contacts may be engaged by two prongs of a proper size and spacing, such as are found on standard insertable plugs. 35

It is one of the objects of our invention to provide a receptacle in which the live contacts cannot be engaged except by an Object having two prongs of a determined size and spacing.

It is another object to provide a receptacle 40 wherein contact with a current-carrying portion thereof can be made only by a two-step operation performed in a definite manner.

It is a further object to provide a receptacle having a barrier which may be released for movement only by the simultaneous action of two prongs of a desired plug.

It is still another object of our invention to provide a receptacle having a barrier which will _g0return to a protecting position as soon as the prongs of the insertable prongs of the plug are withdrawn from the receptacle.

In the accompanying drawings, wherein we have shown for purposes of illustration only a 55 certain presently preferred embodiment of our invention:

Figure 1 is a front view in elevation of a receptacle, but without the cover plate, embodying our invention;

Figure 2 is a front view in elevation showing the receptacle with the cover plate in position;

Figure 3 is a side view in elevation of the receptacle shown in Figure 1, with the cover plate in position, and showing in dotted lines a standard insertable plug with its two prongs in position to unlock the receptacle;

Figure 4 is a view generally similar to that shown in Figure 3, but showing the insertable plug in position with its two prongs engaging the live electric contacts of the receptacle;

Figure 5 is a view in cross section along the line V—V of Figure 1; and

Figure 6 shows a form of insertable plug which may be used with our receptacle.

Our receptacle is adapted to receive any standard plug having two connection prongs which may be inserted by pushing the prongs into apertures prepared for it in a barrier plate to release two locking dogs which engage the barrier or shield plate, whereupon the plug may be raised to move the barrier to a position where the prongs may be inserted further into the receptacle to engage the usual live electrical contacts therein. When the prongs are pulled out of the receptacle, the barrier plate is then moved by springs to a position where the locking dogs engage the barrier plate, in which position the apertures in the barrier position are out of alignment with the contacts. This makes it impossible for any one to engage the electrical contacts by means of an instrument having only-a single prong-like member. Thus the ordinary nail or pin cannot be placed in contact engaging position, either accidentally or on purpose.

In the drawings, wherein similar parts in the several drawings are designated by like numerals, the numeral 10 designates the body of an electrical receptacle or plug-in socket formed from a suitable insulating material such as porcelain or plastic and by any usual method. The body has a base 11, upturned ends 12 and 13, and an upstanding land portion 14 having therein a well depressed portion 15 with sides IS and 17. The well extends to the base 11. Centrally disposed at each end are the usual fastening, ears or lugs 18, of metal secured to the body of insulating material, and having elongated slots 19, by means of which the receptacle may be attached to the usual outlet box.

2,528,014

Electrical contact elements 20 and 21 are secured to the sides 16 and 17 respectively, and on each contact an attachment screw 22 is mounted so that the contacts may be each attached to current carrying or live wires.

Mounted on raised lugs 23 disposed opposite one another and projecting from each of the side members 16 and 17 for arcuate movement around pivots 24 is a barrier plate or shutter 25 formed from an insulating material such as a suitable plastic or porcelain. The barrier or shutter consists of a cylindrical segment 26 from opposite sides of which segmented arms 27 extend to engage pivots 24. The barrier has two aligned spaced apart slots 28 in the segment 26 into which the prongs 30 of an ordinary electrical plug may be passed. The barrier or shutter is so shaped and proportioned as to be received in lower recess 3i and upper recess 32 formed in each of the side walls 16 and Π of well 15. The barrier is biased toward the bottom of the slot or recess 31 by two springs 33. The springs are attached to each arm 27. The other ends of the springs are secured to pins 34 on the base ί I.

Two locking dogs 35 are mounted one on each of the side walls i 6 and 17 for angular movement about the pivot pin 36. Each of the dogs 35 has a detent or projection 37, which engages with a shoulder or tooth 38 on each of the segments 26. The detent and tooth form a latch to hold the barrier in the lower or locked position. The dogs are urged toward the segment 26 (to the left as seen in Figures 3 and 4) by flat springs 39. A tongue portion 42 projects outwardly from each of the dogs 35 to be engaged by the prongs 30 of the plug as will be described. The upper end of detents 37 and the lower portion of the teeth 38 have sloped portions 40 and 41 respectively so that the barrier 25 when urged to locked position by the action of springs 33 after the withdrawal of plug prongs 30 will allow the teeth 38 to slide over the detents 37 until the detents engage the teeth, which occurs when the barrier is in locked position adjacent the bottom of the lower recess 31.

A cover plate 43 is provided with two holes 44 and 45 through which screws may be passed into threaded holes 46 and 47 respectively disposed in the top surface of the land portion ! 4, to secure the plate to the receptacle. In cover plate 43 are two slots 48 and 49, which are of such length and breadth and so spaced as to accommodate the prongs 30 of an ordinary electrical plug, throughout the movements thereof when the plug is moved from the barrier position to the insertible position where the plug prongs may be slid into electrical union with the contact elements 20 and 21.

When the barrier plate 25 is in the lower position or locked position, it is impossible for an object such as a nail to be pushed into the receptacle so as to engage the electrical contacts 20 and 21. In this initial position of insertion the plug cannot make electrical connection directly with the contacts 20 and 21. However, after the insertion of the two prongs of the plug part way into the receptacle the dogs 35 will be released from engagement with the teeth 38 by moving the prongs inwardly (to the right of Figure 3) until the prongs engage and then move the dogs 35 by pressing on the tongues 42. The barrier or shutter 25 may then be moved upwardly from the barrier, locked, or closed position shown in Figure 3 to the unlocked or contact exposed position shown in Figure 4, where the plug prongs 30 may be slid into electrical engagement with the contacts 20 and 21. At the bottom of each of the contacts is a ledge 50 on which the ends of the prongs rest when in engagement with contacts 20 and 21. This is to prevent any unplanned downward movement of the plug, which movement would tend to take place due to the pull of springs 33 should the engagement be loose. When the plug is withdrawn from the receptacle the barrier 25 is promptly moved to the lower or locked position (Figure 4) by the action of springs 33, and held there by the latching means.

In Figure 6 we have shown an electrical plug which may be advantageously used with our invention. This plug has two metal prongs 60 and 61 which extend outwardly in a straight line for a short distance and are then slanted upwardly and may be arranged as to lie along the contacts 20 and 2(.

We have shown an exemplary and presently preferred embodiment of our invention, but it is to be understood that changes may be made in the structure within the scope of the following claims.