GB2178249A - Shutter in socket outlet - Google Patents

Abstract

A socket comprises a housing base (10) accommodating a plurality of contact sockets (41,42,43) and a shutter (60) formed with closure flaps and a guide flap (62,63) which is in engagement with a compression spring (67) urging the shutter (60) to the shielding position, the base (10) being formed with a top opened spring compartment (16) defined by a pair of end walls (17,18) between which the spring (67) is received, one of the end walls (18) being formed with a slit (19) through which the guide flap abuts the spring (67). The assembly of the face plate (30) and base (10) with electrical parts therein clips into bracket (80) for mounting in a wall box (Fig. 3, not shown). <IMAGE>

Description

SPECIFICATION Electric receptacle assembly The present invention relates to an electrical receptacle assembly, and more particularly to an electrical receptacle assembly with a shutter which is urged by a spring into a shielding position of closing unused slots leading to internal contact sockets and is movable to an exposing position of opening the slots by a mating electrical plug for insertion of the prongs of the plug therethrough into the internal contact sockets.

A prior electrical receptacle of this kind is known as disclosed in U.K. Pat. No.

1,212,203 in which, as illustrated in FIGURE 1 of the accompanying drawings, a shutter 2a is movable within a receptacle housing 1 a for movement between a shielding position of closing slots (not seen) leading to internal contact sockets (not seen) and an exposing position of opening the slots allowing insertion of the prongs of a mating electrical plug into the contact sockets. The shutter 2a is engaged at its one end with a spring 3a to be urged thereby to the shielding position and is formed at the other end with an inclined surface 4a for engagement with one of the prongs of the electrical plug so that it is moved against the urgence of the spring 3a to the exposing position, allowing the insertion of the prongs into the contact sockets.The spring 3a is required to be assembled in a fixed position within the housing la to be in exact engagement with the shutter 2a for properly urging the same. To this end, there are introduced a post 5a on the side of the shutter 2a and a projection 6a on the side of the housing 1a to be respectively inserted into the end portions of the spring 3a. In this prior receptacle, however, the spring 3a should be compressed for engagement with the post 5 and the projection 6a when assembled or inserted in the housing la, which requires rather delicate technique and therefore renders the assembly procedure inconvenient, particularly for automated assembly.

It is an object of the present invention to overcome the above problem.

According to the present invention, there is provided an improved electrical receptacle assembly including: a housing of dielectric material accommodating a plurality of contact sockets including a ground contact socket for receiving prongs of a mating electrical plug through associated slots formed in the housing; a shutter movable between a shielding position of closing the slots leading to the contact sockets adapted to be connected to an external power source and an exposing position of opening the same; a compression spring mounted within the housing for urging the shutter to the shielding position; said shutter including opening means for causing movement of the shutter to the exposed position upon insertion of one of the prongs of the electrical plug into the slot leading to the ground contact socket; said housing being composed of an open-topped case body and a face plate formed with said slots and closing the top end of the case body; a spring compartment open at the top of the case body and defined by a pair of spaced end walls between which the length of the compression spring is received, one of the end walls being formed with a slit; said shutter being slidably received between the case body and the face plate with its one end portion positioned between the ground contact socket and the associated slot in the face plate; said shutter being formed with closure flaps and a guide flap, said closure flaps being movable in and out of registering relation with the associated slots, said guide flap extending through said slit into abutment with the one end of the compression spring in the spring compartment so as to be urged thereby in a direction of closing the slots by the closure flaps; and said opening means being formed at the one end of the shutter to be accessible from outside through the slot leading to the ground contact socket.

In a preferred embodiment, the receptacle assembly includes an electrical switch interposed between one of the contact sockets to be connected to the power source and one of line terminals on the housing, said switch including a handle pivotally supported on the housing, a first conductor member extending from the one of the contact sockets and forming a fulcrum at the other end, a Ushaped actuator element having a pair of legs connected by a bight portion swingably supported on said fulcrum, a second conductor member extending from the one of said line terminals to have at its free end portion a fixed contact engageable with a movable contact formed on the leg of said U-shaped actuator element, and an over-center spring having its one end inserted into the U-shaped actuator element and having the other end secured to the handle adjacent the pivot axis thereof for bringing the movable contact into and out of electrical contact with the fixed contact in over-center fashion in response to the manual operation of the handle about its pivot axis.

The receptacle assembly additionally may include a mounting bracket of electrically conductive material secured on the top of the housing by at least one fastening screw penetrating through the housing from the bottom thereof to be threaded into a tapped hole in the mounting bracket. Also included may be a grounding element with a resilient lug and an insertion lug held between the mating surfaces of the case body and the face plate, said resilient lug being urged into contact with said ground contact socket for electrical connection between the ground contact socket and the mounting bracket, whereby an outlet box to which the mounting bracket is secured together with the housing can be grounded for a safety purpose.

Conveniently, the receptacle assembly further includes a cover plate of dielectric material which is adapted to cover the top of the housing while exposing said slots and the handle of said switch therethrough, said cover plate being held within a cover frame of dielectric material secured to said mounting bracket by one or more captive screws, said cover plate covering the inner flange portion of the cover frame including said captive screws and detachably connected to the cover frame by snap engagement of hooks on the back of the cover plate with complementary notches in the inner periphery of the cover frame.

Preferably, the housing is provided with a pair of holes at opposite ends of a first dimension of the housing for receiving therethrough said fastening screws, said case body including an integral lip which is cooperative with like integral lip on the face plate to form a split jaw at an end of a second dimension of the housing which is substantially perpendicular to the first dimension, said mounting bracket being formed with an integral staple which is clamped over said split jaw for intimate engagement between the case body and the face plate and at the same time between the mounting bracket and the resulting housing.

For a better understanding of the present invention and to show how the same may be put into effect, reference will now be made, by way of example to the accompanying drawings, in which: FIGURE 1 is a cross sectional view of a prior electrical receptacle with a movable shutter; FIGURE 2 is an exploded perspective view of an electrical receptacle assembly embodying the present invention; FIGURE 3 is an exploded perspective view of the above electrical receptacle assembly with a cover plate, a mating electrical plug, and an outlet box for mounting the assembly; FIGURE 4 is a top view of the above receptacle assembly with its cover plate and cover frame removed; FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 4; FIGURE 6 is top view of a mounting bracket included in the above receptacle assembly; FIGURE 7 is a front view of the above mounting bracket;; FIGURE 8 is a side view of the above mounting bracket; FIGURE 9 is a top view of the cover frame employed for mounting the cover plate on the housing of the receptacle assembly; FIGURE 10 is an enlarged sectional view taken along line 10-10 of FIGURE 9; FIGURE 11 is an enlarged top view of a portion of the cover frame including a screwretaining hole; FIGURE 12 is a front view of the cover plate; and FIGURE 13 is an exploded perspective view of a modification of the above embodiment in which a pair of housings are supported on a single mounting bracket.

Referring now to the drawings, Figures 2 to 12 illustrate an electrical receptacle assembly in accordance with a preferred embodiment of the present invention. The receptacle assembly comprises a housing 1 of dielectric molding material which is composed of a open topped sase body 10 mounting various components and a face plate 30 closing the top opening of the case body 10, the case body 10 and the face plate 30 being held together by a tapping screw 20 extending through a center hole 26 of the case body 10 from the bottom thereof into the face plate 30. Formed in the face plate 30 are slots 31, 32 and 33 respectively in register with contact sockets 41, 42 and 43 mounted in the case body 10, the slots 31 and 32 serving as live and neutral slots which are in longitudinal alignment and dimensioned to receive live and neutral prongs 111 and 112 of a mating electrical plug 110.The other slot 33 extends in perpendicular relation to the longitudinal direction of the slots 31 and 32 and is dimensioned to receive a ground prong 113 of the plug 110. Also formed in the face plate 30 is a window 34 for passing therethrough a handle 71 of an electrical switch 70, details of which will be discussed hereinafter.

The interior of the case body 10 is divided into a plurality of compartments by integral ribs extending in different directions within the plane of the case body 10. Included in the compartments are first and second compartments 11 and 12 respectively for mounting therein said contact sockets or live and neutral sockets 41 and 42. The live contact socket 41 is electrically connected through a conductor member 44, said switch 70 and another conductor member 45 to a line terminal 51 with a terminal screw 54 held at a peripheral end of the case body 10. The conductor member 44 has its one end fastened to the live contact socket 41 within the first compartment 11 and extends therefrom to terminate at the other end in a switch compartment 15 in which a portion of the switch 70 is received. The neutral contact socket 42 is received in the second compartment 12 and connected through a L-shaped conductor 48 to a line terminal 52 with a terminal screw 55 which line terminal 52 being held at the peripheral end opposite to said line terminal 51.

The remaining contact socket or ground contact socket 43 is mounted within a third compartment 13 and is connected through a Sshaped conductor 49 to a ground terminal 53 with a terminal screw 56, said ground terminal 53 being held in a fourth compartment 14 adjacent to the third compartment 13. Said conductor member 44 is formed at its end a bent ridge defining a fulcrum 46 on which is swingably supported a U-shaped actuator 74 with a movable contact 75 on the exterior of one of its legs for movement between a closed position where the movable contact 75 is in electrical contact with a fixed contact 47 on the end of said conductor member 45 leading to the live line terminal 51 and an open position where the movable contact 75 is out of electrical contact with the fixed contact 47.A pair of fingers 76 project on either side of the bight portion or bottom of the Ushaped actuator 74 to define therebetween a groove into which a vertical rail 21 on the side wall of the switch compartment 15 fits for positively locating the actuator 74 on the fulcrum 46.

The actuator 74 constitutes said electrical switch 70 together with said handle 71 and an over-center spring 77 connecting the actuator 74 and the handle 71. The handle 71 has on its either side an integral projection 72 with a knife edge 73 at the upper end thereof, which knife edge 73 is in point contact with the root of an indentation 35 (only one of which is shown in FIGURE 2) formed inside of each side wall of said window 34 for pivotal or swinging movement about a horizontal axis passing through the roots of the indentations 35.Said over-center spring 77 is interposed in a compressed manner between the handle 71 and the actuator 74 with its end portions inserted respectively into the bottom of the handle 71 and the actuator 74 so that the spring 77 snaps over-center in response to the manual swinging movement of the handle 71, causing the actuator 74 to move between said open and closed positions and holding the same stably either of the positions. Assembled into the housing 1 is a shutter 60 of dielectric material which prevents foreign objects or the like from being inserted into the contact sockets 41 and 42 when the receptacle is not in use.The shutter 60 is in the form a pair of horizontally extending closure flaps 61 integrally connected by a web 62 with a downwardly extending guide flap 63 and is urged by a compression spring 67 in a direction of closing said live and neutral slots 31 and 32 by the closure flaps 61 to prevent the insertion of the prongs 111 and 112 into the corresponding contact sockets 41 and 42. Said spring 67 is received in a spring compartment 16 formed between the first and second compartments 11 and 12 in longitudinal alignment with said third compartment 13. The spring compartment 16 is dimensioned to receive the length of the spring 67 in a relaxed condition between opposed end walls 17 and 18, one of which separates the spring compartment 16 from the third compartment 13 and is formed therein with a slit 19 for intercommunication therebetween.

Said shutter 60 is held between the case body 10 and the face plate 30 with the guide flap 63 inserted into the slit 19 and with feet 65 (only one of which is seen in FIGURE 2) on the underside of the closure flaps 61 slidably supported on the side walls of the spring compartment 16. The guide flap 63 thus inserted into the slit 19 has its rear edge in abutting engagement with the one end of the spring 67 so that the shutter 60 is urged thereby in a direction of extending the closure flaps 61 over the contact sockets 41 and 42 in the first and second compartments 11 and 12 and at the same time closing the corresponding slots 31 and 32.A pair of stop projections 64 (only one of which is seen in FIGURE 2) are formed on the shutter 60 just rearwardly of the upper end of the guide flap 63 for preventing the entire guide flap 63 from being moved out of the slit 19 into the third compartment 13. The upper end of the guide flap 63 is in the form of an inclined edge 66 which is accessible through the ground slot 33 in the face plate 30 to be engageable with the ground prong 113 of the plug 110.The ground prong 113 when engaged with the inclined surface 66 pushes the shutter 60 against the spring 67 into an exposing position of opening the slots 31 and 32 from a shielding position of closing the same, allowing the insertion of the prongs 111 and 112 into the live and neutral contact sockets 41 and 42, at the same time allowing the ground prong 113 to be inserted into the ground contact socket 43 in the third compartment 13 from which the guide flap 63 has been retracted. During this movement between the shielding and exposing positions, the guide flap 63 is caught within the slit 19 so as to be guided thereby for smooth and reliable operation of the shutter 60.With this arrangement, the shutter 60 and the spring 67 can be mounted separately in such a manner that the length of the spring 67 is firstly inserted in the spring compartment 16 without being compressed and then the shutter 60 is incorporated in the case body 10 with its guide flap 83 extending into the slit 19 in the end wall 18 of the spring compartment 18 for abutment with the end of the spring 67, enabling an easier assembly thereof into the housing 1 than required in the prior receptacle of FIGURE 1 where the shutter and the spring should be assembled together into the housing with the spring being held compressed, thus making the assembly particularly advantageous for automated techniques.

The body case 10 and the face plate 30 between which the shutter 60 is mounted can be held together by a pair of fastening screws 22 in addition to said tapping screw 20. The fastening screws 22 extend from the bottom through apertures 23 in the opposite end por tion of the case body 10, apertures 36 in the marginal portion of the face plate 30, and are each engaged with tapped holes 81 of a mounting bracket 80 for securing the housing 1 to the mounting bracket 80 which is incorporated to mount the receptacle assembly onto a conventional wall outlet box 120 or the like into which is routed a power cable 130 including live, neutral and ground wires 131, 132, and 133, as illustrated in FIGURE 3.For mounting the receptacle assembly to the outlet box 120, mounting screws 82 are used to extend through elongated holes 83 in the periphery of the mounting bracket 80 for engagement in tapped holes 122 formed in inwardly bent mount tabs 121 respectively of the outlet box 120 after the wires 131, 132, and 133 of the power cable 130 have been connected to the corresponding terminal screws 51, 52, and 53. It is noted at this time that one of said fastening screws 22 serves to electrically connect the ground terminal 53 with the mounting bracket 80 and the outlet box 120 secured thereto. For this purpose, a grounding element 50 in the form of L-shaped member composed of an insertion lug 57 and a resilient lug 58 is utilized in association with the ground terminal 53 and the fastening screw 22.The insertion lug 57 is formed with an eye 59 and is held between the mating surfaces of the case body 10 and the face plate 30 with the eye 59 in register with the apertures 23 and 36 through which the one of the fastening screws 22 extend for electrical connection of the grounding element 50 with the mounting bracket 80 by way of the fastening screw 22. The resilient lug 58 extends into the third compartment 13 to be in pressed contact with the end of said Sshaped conductor 49 leading to said ground terminal 53 so that the mounting bracket 80 and the outlet box 120 can be grounded by way of the grounding element 50 and the fastening screw 22.In this manner the outlet box 120 and the mounting bracket 80 are grounded by better utilization of the one of the fastening screws 22 which fasten together the case body 10 and the face plate 30 and securing the resulting housing 1 to the mounting bracket 80.

Said case body 10 is formed with an integral lip 24 which is cooperative with like integral lip 37 on the side of the face plate 30 to form a split jaw at an end of one dimension of the housing 1 which is in perpendicular relation to the dimension along which the apertures 36 are aligned. Formed at the corresponding end of the mounting bracket 80 is an integral staple 84 which depends therefrom to be clamped over said split jaw or mating lips 24 and 37 for tight fastening of the housing 1 with the mounting bracket 80, retaining the face plate 30 firmly between the mounting bracket 80 and the case body 10. Such clamping is done with the bottom side of the staple 84 being pressed by a suitable tool to be deformed into a concave portion 25 in the bottom of the lip 24.

Attached onto the mounting bracket 80 is a cover frame 90 of dielectric material within which is fitted a cover plate 100 concealing the mounting bracket 80 thereunder while exposing the portions of the housing 1 including the slots 31, 32 and 33, and the switch handle 71 through respective openings 101 and 102. Said cover frame 90 includes at its inner flange 91 a pair of opposed corrugated portions 92 of relatively small thickness, as best seen in FIGURES 9 and 10. Each of the corrugated portions 92 is separated by a slit 93 from a raised rim 94 around the outside of the frame 90 and is continuous only with the adjacent flange portions 91 of larger thickness so that it is resiliently movable in a direction perpendicular to the plane of the frame 90 to a limited extent in relation to the remaining portion of the cover frame 90.Formed in each of the corrugated portions 92 is a screw-retaining hole 95 having therein equiangularly spaced segments 96 with sharpened edges of relatively small thickness which are to be engaged with the thread of a captive screw 97 extending through the hole 95 for retention thereof. The captive screws 97 thus retained in the holes 95 are engaged respectively with tapped holes 86 in mounting bracket 80 for securing the cover frame 90 thereto, each hole 86 being formed in a raised tab 85 struck from the mounting bracket 80 to be integral therewith.Said corrugated portions 92 of limited resiliency are responsible for inti- mate mounting of the cover frame 90 on a wall or the like supporting surface 123 around the periphery of the outlet box 120, since tightening the captive screw 97 causes the corrugated portions 92 to move closer to the mounting frame 80 as resiliently dragging the cover frame 90 into pressed contact with the supporting surface 123. The cover plate 100 is removably received inside of the cover frame 90 with its depending hooks 103 in snap engagement with notches 98 in the periphery of the inner flange 91 of the cover frame 90 to conceal the mounting bracket 80 and the inner flange 91 of the cover frame 90.

FIGURE 13 illustrates a modification of the above embodiment in which a pair of the receptacle housings 1 are supported together by a single mounting bracket 140. The receptacle housing 1 is identical in construction to that of the above embodiment and therefore like numerals designates like parts. In this modification, the housings 1 are electrically coupled by the use of jumper cords 151, 152 and 153, respectively for connection between the live terminals 51, between neutral terminals 52, and between the ground terminals 53 of the two housings 1. For this purpose, each housing 1 is provided in its bottom with a corresponding number of access ports (not seen) through which the jumper cords can be inserted to the desired terminals.The mounting bracket 140 is formed to have a pair of mount openings 142 respectively for receiving therein the upper portions of the housings 1 each secured to the mounting bracket 140 by means of a pair of like fastening screws (not seen) plus the like staples 144, as in the same way in the above embodiment. As shown in the figure, the tapped holes 141 for the fastening screws are located at the portion other than the intermediate section between the mount openings 142 so that the housings 1 can be held closer to each other, reducing the width dimension of the mounting bracket 140 along which the housings 1 are aligned for compacting the overall receptacle assembly including a cover frame 160 and a cover plate 170 with openings 171 and 172 for receiving the portions of the housings 1 and the switch handles 71, both of the frame 160 and the cover plate 170 being of like constructions as in the above embodiment but of different dimensions.

Claims (8)

1. An electrical receptacle assembly including: a housing of dielectric material accommodating a plurality of contact sockets including a ground contact socket for receiving prongs of a mating electrical plug through associated slots formed in the housing; a shutter movable between a shielding position of closing the slots leading to the contact sockets adapted to be connected to an external power source and an exposing position of opening the same; a compression spring mounted with the housing for urging the shutter to the shielding position; said shutter including opening means for causing movement of the shutter to the exposed position upon insertion of one of the prongs of the electrical plug into the slot leading to the ground contact socket; said housing being composed of an open topped case body and a face plate formed with said slots and closing the top of the case body; a spring compartment open at the top of the case body and defined by a pair of spaced end walls between which the length of the compression spring is received, one of the end walls being formed with a slit; said shutter being slidably received between the case body and the face plate with its one end portion positioned between the ground contact socket and the associated slot in the face plate; said shutter being formed with closure flaps and a guide flap, said closure flaps being movable in and out of registering relation with the associated slots, said guide flap extending through said slit into abutment with the one end of the compression spring in the spring compartment so as to be urged thereby in a direction of closing the slots by the closure flaps; and said opening means being formed at the one end of the shutter to be accessible from outside through the slot leading to the ground contact socket.

2. An assembly according to claim 1 further including an electrical switch interposed between one of the contact sockets to be connected to the power source and one of line terminals on the housing, said switch including a handle pivotally supported on the housing, a first conductor member extending from the one of the contact sockets and forming a fulcrum at the other end, a U-shaped actuator element having a pair of legs connected by a bight portion swingably supported on said fulcrum, a second conductor member extending from the one of said line terminals to have at the other end portion a fixed contact engageable with a movable contact formed on the leg of said U-shaped actuator element, and an over-center spring having its one end inserted into the U-shaped actuator element and having the other end secured to the handle adjacent the pivot axis thereof for bringing the movable contact into and out of electrical contact with the fixed contact in over-center fashion in response to the manipulation of the handle about its pivot axis.

3. An assembly according to claim 1 or 2, including a mounting bracket of electrically conductive material secured on the top of the housing by at least one fastening screw penetrating through the housing from the bottom thereof to be threaded into a tapped hole in the mounting bracket, and further including a grounding element with a resilient lug and an insertion lug held between the mating surfaces of the case body and the face plate, said resilient lug being urged into contact with said ground contact socket for electrical connection between the ground contact socket and the mounting bracket.

4. An assembly according to claim 3, including a cover plate of dielectric material which is adapted to cover the top of the housing while exposing said slots and the handle of said switch therethrough, said cover plate being held within a cover frame of dielectric material secured to said mounting bracket by one or more captive screws, said cover plate covering the inner flange portion of the cover frame including said captive screws and detachably connected to the cover frame by snap engagement of hooks on the back of the cover plate with complementary notches in the inner periphery of the cover frame.

5. An assembly according to claim 3 or 4, wherein said housing is provided with a pair of holes at opposite ends of a first dimension of the housing for receiving therethrough said fastening screws, said case body including an integral lip which is cooperative with like integral lip on the face plate to form a split jaw at an end of a second dimension of the housing which is substantially perpendicular to the first dimension, said mounting bracket being formed with an integral staple which is clamped over said split jaw for intimate engagement between the case body and the face plate.

6. An electrical receptacle assembly substantially as hereinbefore described with reference to and as illustrated in Figures 2 to 12 of the accompanying drawings.

7. An electrical receptacle assembly substantially as hereinbefore described with reference to and as illustrated in Figure 13 of the accompanying drawings.

8. Any novel feature or combination of features described herein.