Automatic locking electrical outlet

[0001] This application relates to an improvement of the automatic locking electrical outlet disclosed and claimed in U.S. Pat. No. 7,172,451, issued on Feb. 6, 2007, which is incorporated by reference herein. The outlet disclosed and claimed in the '451 patent is more complex and difficult to manufacture than the outlet of the present invention in which the number of moving parts and the use of more costly high tensile, high elasticity metals have been eliminated.

[0002] The invention is directed to an electrical receptacle or other outlet that houses a wiring system for electrical current to run standard male plug-in electrical devices. More particularly, the invention is directed to automatic locking outlets including female plugs or sockets for mounting to extension cords, female receptacles that automatically are locked to prevent disconnection when connected to standard male plugs.

[0003] Female locking outlets for extension cords are well known in the art; see, e.g., U.S. Pat. Nos. 3,710,304; 4,136.919; 5,352,132; and 5,413,498. In these prior art references, a female locking outlet incorporates a pair of release buttons, unlocking pins, or locking balls that fit into the apertures of a standard male plug. However, none of these prior art locking receptacles automatically lock when the male plug is connected to the receptacle.

[0004] There is a need for a female locking electrical outlet that automatically locks when the male plug is connected to an extension cord outlet or wall receptacle. There is also a need for a less complex and easier to manufacture female locking electrical outlet than those of the prior art.

[0005] One embodiment of an automatic female locking electrical outlet of the present invention includes an outlet body having at least one pair of slots for apertured prongs of a male electrical plug, a pair of receptacles for each of the at least one pair of slots respectively mounted within the outlet body, a locking member having inner ends inwardly angled toward a longitudinal axis of the outlet and locking tabs that are positional within apertures in the prongs to place the outlet in a locked position when an electrical plug is connected to the outlet, and at least one unlocking or release mechanism having a release member for engaging the locking member and to transition the locking member from the locked position to an unlocked position.

[0006] The automatic female locking electrical outlets or receptacles of the present invention include female plugs or sockets for mounting to extension cords, receptacles for wall mounting and for use in portable generators, UPS (uninterrupted powers supply) systems, and other auxiliary power sources containing female receptacles that automatically are locked to prevent disconnection when connected to standard male plugs.

[0007] In the embodiment of an automatic female locking electrical outlet of the present invention suitable for use as a locking wall receptacle, the outlet includes an outlet body having two pair of slots within the body for the apertured prongs, a pair of receptacles for each of the two pairs of slots, a locking member with locking tabs that are positional within the prong apertures to automatically place the outlet in a locked position when an electrical plug is connected to the outlet, and a release mechanisms having a release members for engaging the locking member and to transition the locking member from the locked position to an unlocked position. The outlet body is designed to fit into the opening of a standard outlet box and to be attached to a standard outlet box for mounting to a wall.

[0037] FIGS. 1-9 show various views of one embodiment of the locking electrical outlet present invention. Specifically, FIG. 1 shows an electrical outlet 10 having over-mold 11 capable of being mounted at the end of a standard extension cord 12 having a strain relief section 13. Outlet 10 has a pair of slots 14 for accepting negative and positive prongs 16 with apertures 17 of a standard male electrical plug 18 and a ground slot 20 for accepting a ground 19 of plug 18. Strain relief section 13 is used in cord manufacture to prevent the pulling load on cord 12 of varying gauges and lengths from being transmitted to the receptacle 10. FIG. 1 represents only one of numerous uses of locking outlet 10. It is apparent that outlet 10 can be made as a replacement outlet for use on all types of existing electrical cords.

[0038] FIGS. 2 and 3 show various exploded views of the internals of female locking electrical outlet 10. The internals of outlet 10 that are mounted within over-mold 11 include receptacle housing cover 30, receptacle housing body 32, an insulator 34, a pair of receptacles 38, a locking member 68, standard ground receptacle 40, LED (light emitting diode) 44, release mechanism 48 having release member 50 at the inner end of release button 54, and a cover 58. Cover 58 is preferably made of a rubber weather resistant material. Although LED 44 is preferably included with the embodiment of the outlet 10 shown in FIGS. 23, use of an LED is not essential. Cover 58 fits over the outer end 59 of release button 54 and protrudes from over-mold 11 to protect the user from electrical shock. Insulator 34 is a non-conducting material such as a thermoplastic and is attached to housing body 32 between the pair of receptacles 38 as shown in FIGS. 2, 5, 5A and 5B.

[0039] FIGS. 4 and 5 show the respective rear and top views of the assembled internals of the female locking electrical outlet 10. The pair of receptacles 38 has flanges 60 for receiving the respective positive and negative lead lines (see FIGS. 6B, 7B and 9), outer arm 62 and inner arm 64. Outer arm 62 and inner arm 64 are U-shaped to form the receptacle for making electrical contact with prongs 16 of plug 18.

[0040] FIGS. 5A and 5B show the critical automatic locking function of the present invention using the locking tabs 66 that are molded into the inner surfaces of the locking members 68 mounted between outer arms 62 of receptacles 38. The size of tab 66 is designed to easily fit within apertures 17 of prongs 16 when outlet 10 is in the locked position as described in detail below. To assure that the locking member has sufficient force for the locking function, the locking member used in the present invention is preferably plastic and the tabs are metal. Preferably the locking member is molded from a thermoplastic having sufficient resiliency to be able to flex from the locked to the unlocked position and to return the locking tabs to their locked state. This feature allows for the automatic locking of outlet 10 to plug 18 when a user easily slides prongs 16 of plug 18 over tabs 66 as tabs 66 are positioned into apertures 17.

[0041] The locking tabs 66 can be implemented several different ways. For example, a small metal ball bearing or a BB can be embedded into the molten thermoplastic during the molding process of the locking member as shown in FIGS. 5A and 5B. Alternatively, the locking member 68 may stamped from a thin piece of sheet metal having pressed or dimpled locking tabs therein. The entire surface of the metal locking member is then over-molded with the thermoplastic except for the locking tabs. The locking member 68 is sized to fit between the pair of receptacles 28 as shown in FIGS. 5A and 5B. The locking tab has the same diameter as the aperture of a standard plug.

[0042] Release button 54 is mounted through orifice 69 in end 70 of housing cover 30 (shown in FIG. 4). Outlet 10 is in the unlocked position after a user pushes cover 58. This causes button 54 and the outwardly angled ends 74 of release member 50 to slide along the inwardly angled ends 77 of locking members 68 until tab 66 is completely moved out of receptacle 38 as shown in FIG. 5B.

[0043] FIGS. 6A and 6B show the perspective frontal and rear views of outlet 10 in its fully locked position, i.e., after electric plug 18 is connected to outlet 10 and locking tabs 66 are lodged within the respective apertures 17 of prongs 16.

[0044] FIGS. 7A and 7B show the respective frontal and rear views of outlet 10 in the unlocked position after electric plug 18 is released from outlet 10 and locking tabs 66 are dislodged from the respective apertures 17 of prongs 16 as the result of the user pushing in on cover 58 on button 54.

[0045] Outlet 10 is considered an automatic locking electrical outlet because outlet 10 is in the locked position as soon as the user inserts plug 18 entirely into outlet 10 so that end 76 of plug 18 is flush with outer surface 78 of outlet 10. As the user inserts plug 18 into outlet 10, prongs 16 slide within slots 14 and into the respective receptacles 38. When prongs 16 come into contact with locking tabs 66, they urge against the tabs until locking tabs 66 come into alignment with apertures 17. When plug end 76 is flush with outer surface 78, locking tabs 66 are positioned within apertures 17 and are fully lodged within apertures 17 to prevent removal of outlet 10 as shown in FIGS. 6A and 6B.

[0046] Plug 18 is removed from outlet 10 when the user presses cover 58 which in turn urges release button 54 of release mechanism 48 forward and causes release member ends 74 of release member 50 to press against inwardly angled ends 77 of locking members 68 of receptacle 38. Preferably, release member outwardly angled ends 74 are tapered to match the slope of inwardly angled ends 77. As outwardly angled ends 74 are urged against inwardly angled ends 77, outlet 10 transitions from the locked position to the unlocked position. Specifically, respective locking tabs 66 move inward toward the longitudinal axis 84 of outlet 10 and away from and completely out of apertures 17 to enable the user to remove plug 18 from outlet 10. In the unlocked position, locking tabs 66 are in their maximum inward position with respect to longitudinal axis 84 of outlet 10 (shown in FIG. 8).

[0047] FIG. 8 shows a rear view of a pair of receptacles 38 a locking member 68 with release member 50 in the locked position. In the locked position, locking tabs 66 are in their maximum outward position with respect to horizontal axis 84. This is achieved when release button 54 has been fully pressed forward toward slots 14 so that shoulders 88 (shown in FIG. 5) of release button 54 are adjacent and in close proximity to, but not in contact with, inner ends 92 of receptacles 38.

[0048] Preferably receptacles 38 are made of a suitable electrical conducting material, e.g., brass. Each locking member 68 is preferably manufactured by being stamped out of the same piece of metal as locking tabs 66 and has a thickness in the range of about 0.015 to about 0.05 inch, and still more preferably a thickness of about 0.025 inch. Locking member 68 is then coated with a thin layer of thermoplastic as described above to prevent the locking member from making electrical contact with receptacles 38. Each of the receptacles 38 is a unitary U-shaped piece having a flange 60 on the lower side of receptacles 38 between outer arm 62 and inner arm 64 adjacent inner end 92. The outer end 94 of receptacles 38 is mounted adjacent slot 14. Outer arm 62 forms the outer loop and inner arm 64 forms the inner loop of U-shaped receptacles 38 that in turn forms the receptacle for one of apertured prongs 16.

[0049] Release button 54 of release mechanism 48 is joined to release member 50 by tongue 98 (shown in FIG. 5) to provide a slight offset toward the top of outlet 10. This offset and the fact that release button 54 has a width greater than tongue 98 allows for shoulders 88 to be pushed into close proximity to inner ends 92 when outlet 10 is in the unlocked position as discussed above. Release mechanism 48 is of unitary construction and made of a non-conducting material.

[0050] FIG. 9 shows the electrical connection for outlet 10 in which the negative lead line 93 and positive lead line 94 are crimped into flanges 60 of receptacles 38. In one embodiment of the outlet of the present invention, LED 44 is included. In this embodiment, negative lead line 95 and positive lead line 96 from receptacles 38 are directly connected to LED 44 as shown so that LED 44 is always lit when electrical current is flowing even when outlet 10 is in an unlocked position. Ground wire 97 is shown connected to ground lug 99.

[0051] FIGS. 10-17B show various views of another embodiment of the present invention in which a female wall receptacle 100 is designed so that outlet body 102 fits within the opening of a standard outlet plate 110 and the internals of receptacle 100 can be mounted within a standard outlet box 111, the back of which is shown in FIGS. 15A 17B.

[0052] FIG. 14 shows the exploded view of the internals of female locking wall receptacle 100 that include outlet body 102, slots 114 for accepting the negative and positive prongs 16 of plug 18, ground slot 120, a pair of receptacles 138 for each of the slots 114, a locking member 168, mounting tabs 140 on outlet body 102 for attaching outlet body 102 with the screws shown on FIG. 10 to standard outlet plate 110, release mechanism 148 having release arm 154, and release button 158.

[0053] Outlet 100 has the same automatic locking feature as described above in connection with outlet 10. Outlet 100 is automatically in the locked position as soon as the user inserts plug 18 entirely into outlet 100 so that end 76 of plug 18 is flush with outer surface of outlet 100. As the user inserts plug 18 into outlet 100, prongs 16 slide within slots 114 and into the respective receptacles 138 having outer arm 162 and inner arm 164. When prongs 16 come into contact with locking tabs 166, they urge against the tabs until locking tabs 166 come into alignment with apertures 17. When plug end 76 is flush with outer surface of outlet body 102, locking tabs 166 are positioned within apertures 17 and are fully lodged within apertures 17 to prevent removal of outlet 100. Plug 18 is removed from outlet 100 when the user presses button 158 which in turn urges release arm 154 of release mechanism 148 forward and causes release member sidewall 174 of release mechanism 148 to press against outwardly angled ends 168 of the locking members 169 of receptacle 138. Release member outwardly angled sidewalls 174 are sloped to match the slope of outwardly angled ends 168 of the locking members 169 in the same manner as angled ends 74 are tapered to match the slope of inwardly angled ends 77 in outlet 10. In the same manner as in outlet 10 as inwardly angled sidewalls 174 of receptacle 100 are urged against outwardly angled ends 168, outlet 100 transitions from the locked position to the unlocked position. Specifically, respective locking tabs 166 move outward toward the horizontal axis 184 of outlet 100 and away from and completely out of apertures 17 to enable the user to remove plug 18 from outlet 100. In the unlocked position, locking tabs 166 are in their maximum outward position with respect to horizontal axis 184 of outlet 100 (shown in FIG. 17B).

[0054] Electrical connection of receptacle 100 can be made to conduit fed to the standard wall outlet box 111 by means well known to those skilled in the art. For example, brass and silver screws can be tightened to orifices (not shown) in the inner ends of receptacles 138 and the negative and positive lines are connected to the respective screws. In a similar manner, a grounding screw can be connected to the bare wire of the conduit, which is connected to a grounded receptacle. Alternatively, receptacles 138 can include flanges 60 for receiving the respective positive and negative lead lines and a ground receptacle 99 for receiving the bare ground wire that is described in the foregoing description of outlet 10 with reference to FIG. 9.

[0055] FIGS. 11A-11C and 12A-12C show the function of locking cylinder 190 that permits outlet 100 to have three locking options after a user rotates pointer 192 on the outer end of cylinder 190 and extending from the outer surface of outlet body 102 to one of three positions, i.e., standard, locked and unlocked. Locking cylinder 190 is rotated after a user inserts a proprietary key or other similar device (not shown) into pointer 192. The rotation of locking cylinder 190 causes a rotation of button stop 196 that is mounted over the inner end of cylinder 190.

[0056] The standard position of receptacle 100 is shown in FIGS. 10, 11A, 12A, 13 and 14. In the standard position, a user rotates cylinder 190 so that pointer 192 points to “STD” on outlet body 102 causing button stop 196 to rotate to a vertical position with respect to horizontal axis 184. Therefore, when a user inserts plug 18 into outlet 100, locking tabs 166 will automatically lock into the apertures 17 of plug 18 and when a user presses button 158 arms 154 are urged to pivot release mechanism 148 and surface 174 to urge locking member 168 away from apertures 17 and disengaging tabs 166 from aperture 17 allowing the user to remove plug 18 from outlet 100 as described in great detail in the foregoing description.

[0057] The locked position of receptacle 100 is shown in FIGS. 11B and 12B. In the locked position, a user rotates cylinder 190 so that pointer 192 points to “LOCKED” on outlet body 102 causing button stop 196 to rotate counterclockwise to a first horizontal position. In this position, the notched inner end of plug 158 is lodged between the inner surface of outlet body 102 and button stop 196 and prevents a user from pressing button 158 inward. This permits a user to insert plug 18 in a conventional manner and to lock plug 18 in place so that only a user having the proprietary key will be able to unlocked receptacle 100. This is useful in, e.g., medical situations, to allow only authorized personnel having the key to turn off critical equipment.

[0058] The unlocked position of receptacle 100 is shown in FIGS. 11C and 1C. In the unlocked position, a user rotates cylinder 190 so that pointer 192 points to “UNLOCKED” on outlet body 102 causing button stop 196 to rotate clockwise to a second horizontal position. In the unlocked position, a user has pressed button 158 so that the notched inner end of plug 158 is pushed inward past button stop 196 before rotating cylinder 190 in the clockwise direction. Button stop 196 is urged in front of and against the notched inner end of plug 158 to prevent plug 18 from being locked into receptacle 100. This permits a user to insert and to remove plug 18 in a conventional manner without the automatic locking feature of the present invention.

[0059] Without departing from the spirit and scope of this invention, one of ordinary skill in the art can make various changes and modifications to the device of the present invention to adapt it to various usages and conditions. For example, while the female locking outlets are normally orientated along a generally longitudinal axis and the wall receptacle along a horizontal axis with respect to the locking tabs, modifications can be made to this orientation without adversely affecting the effectiveness of the locking function. As such, these changes and modifications are properly, equitably, and intended to be, within the full range of equivalents of the following claims.