|Publication number||US3838383 A|
|Publication date||Sep 24, 1974|
|Filing date||Jun 7, 1973|
|Priority date||Jun 7, 1973|
|Publication number||US 3838383 A, US 3838383A, US-A-3838383, US3838383 A, US3838383A|
|Inventors||Powell A, Wilbur R|
|Original Assignee||Powell A, Wilbur R|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (21), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent Wilbur et al.
[ Sept. 24, 1974 Filed:
DEVICE FOR PREVENTING DISENGAGEMENT OF ELECTRICAL CORD FROM WALL OUTLET Inventors; Raymond Francis Wilbur, 3329 Quesada Dr., San Jose, Calif. 95122; Alva Leroy Powell. PO. Box 2, South San Francisco, Calif. 94080 June 7, 1973 Appl. No.: 367,851
US. Cl. 339/75 1?, 339/103 R Int. Cl Htllr 13/54 Field of Search 339/7579,
References Cited UNITED STATES PATENTS 10/1937 Roberts et a1. 339/75 P 2,761,112 8/1956 Torcivia 339/75 P 2,913,791 11/1959 Martin 339/75 P 3,102,922 9/1963 Lashmutt 339/75 P 3.431,537 3/1969 Klingenberg 339/75 P 3,499,103 3/1970 Pearce 339/103 R Primary ExaminerJOSph H. McGlynn Attorney, Agent, or FirmRobert Charles Hill ABSTRACT A device for preventing accidental disengagement of an electrical cord from an electrical wall outlet has means for releasably securing same to an electrical cord in a locked position thereto. The device also has means for releasably locking same to an electrical wall outlet while permitting disengagement therefrom if a force is supplied thereto which would damage either the cord or the wall outlet.
6 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to a device for preventing accidental disengagement of an electrical cord from an electrical wall outlet. More particularly. the invention relates to such a device which is of simple construction and which may normally be attached to the cord in a manner which permits quick and easy connection of the cord to the wall outlet.
One of the problems encountered in the operation of movable electrical powered devices. such as vacuum cleaners. portable saws. hedge clippers. power mowers. and the like. is accidental disconnection of the clectri cal cord from the electrical outlet. While such a disconnection can. in some instances. be dangerous to the operator of such devices. it usually constitutes a frustrating annoyance and hinders the rapid completion ofthe operation being performed since the operator is continually interrupted by a loss of electrical power.
Accordingly. the primary object of the present invention is to provide a mechanism which will prevent accidental disconnection of an electrical cord from an electrical outlet. but which will at the same time permit such a disconnection before damage is done either to the cord or the electrical outlet.
The above and other objects and advantages of the invention'will become apparent upon consideration of the following specification and the accompanying drawing wherein there are shown preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exploded perspective view of the device of the present invention.
FIG. 2 is a cross-sectional view of the device of the present invention.
FIG. 3 is a perspective view showing the invention set up in actual operating condition.
FIG. 4 is a perspective view showing the device in association with the cord of a vacuum cleaner.
FIG. 5 is a cross-sectional view of the locking element showing grooves therein.
FIG. 6 is a cross-sectional view of the locking element showing a pair of inner walls thereon.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. I in conjunction with FIG. 2. the device of the present invention comprises an electrical outlet cover plate 10. The cover plate 10 has the usual electrical outlet openings 12 and I4 and a hole 16 through which a threaded number l7 (see FIG. 3) may be used to attach the cover plate to a wall. The cover plate of the present invention is unique in that it is provided with a hole I8 having one or more slots 20 extending therefrom. The purpose of the hole and slot arrangement will become apparent subsequently.
A resilient. relatively hard. rubber insert 22 is provided with a rivet-like member 24 extending therethrough and firmly secured within the rubber insert. As best shown in FIG. 2. the rubber insert 22 is of a generally l'rustowonieal shape with the head 26 of the rivet 24 embedded in the larger diameter end of the insert. It should also be noted that the other end of the rivet 24, which protrudes beyond the smaller diameter end of rubber insert 22, is provided with a notched portion 28. When the device is assembled. the rubber inserts 22 may be easily attached to the cover plate 10 by inserting the notched end portion 28 of the rivet 24 into the specially provided hole 18 until the notch 28 is in alignment with a slot 20 and thereafter sliding the notch Iat-.
erally along the slot so that the rubber insert 22 will then be securely fastened to the cover plate 10. as shown in FIGS. 2 and 3.
The device of the present invention further comprises a generally U-shaped clamp member 30 which is preferably constructed of metal. The clamp 30 has inwardly sloping side walls 32 and 34 so that the clamp may be slid laterally into a locked position about the outside of the larger diameter end of the frusto-conical shaped side walls of the rubber insert 22 (see FIG. 2 for assembled position). At this juncture it should be noted that. due to the shape of walls 32 and 34 and the manner in which they fit about insert 22, the clamp 30 may be removed from the insert 22 only by the application of a rather substantial vertical pulling force. In addition. the clamp 30 is provided with a threaded member 36 extending perpendicularly outwardly from the center portion of the top thereof.
A cord locking element 38 is provided with a hole 40 located centrally in the top thereof for engaging the cord locking element to the threaded member 36 of the clamp 30. such as by means of wing nut 39. The cord locking element 38 has depending side walls 42 and 44 for confining a cord. such as an electrical cord. in fixed position between the cord locking element 38 and the top of the clamp member 30. Thus. as best shown in FIG. 3 taken in conjunction with FIG. 2. an electrical cord 46 may be looped about threaded member 36 of the clamp 30 and then rigidly held in place by means of the cord locking element 38.
Although not shown in the drawings. it should be noted that the cord locking element 38 could be formed with two grooves 47 extending through the underside of the top portion and parallel to the side walls 42 and 44. The purpose of such grooves would be to more securely engage and hold the cord 46 in rigid position. Also. instead of grooves. another pair of inner side walls 43 and 45 could be provided to form channel-like passages on each side of the hole 40. through which the cord 46 could be passed and thereby securely held in place.
FIG. 4 shows the device in actual operation. In FIG. 4 a vacuum cleaner having a cord 46 extending therefrom is being operated with the device of the present invention. It should be noted that the combination of elements comprising the insert 22, the clamp 30 and cord locking element 38. hereinafter referred to as the cord clamping means. normally are attached to the cord 46 of an electrical device. such as vacuum cleaner 50. and left there. Thus. when moving the device from room to room. where specially constructed wall plates 10 (with hole 18 and slot 20) have previously been provided at all major electrical outlets. it is a simple matter to engage the notched portion 28 of rivet member 24 with the hole l8 and slot 20 of the cover plate.
When operating an electrical device. such as vacuum cleaner 50, the operator will frequently inadvertently reach full extension of cord 46 without being aware of same. Usually this results in the annoyance of disconnecting the plug on cord 46 from the electrical wall outlet. However, as can be easily observed, the present invention prevents the cord from being pulled from the wall outlet while still letting the operator realize he has reached maximum cord length. Should the operator give a rather abnormal and violent jerk on the cord 46, the clamp 30 will disengage from the resilient rubber insert 22. In the event that the clamp 30 should not disengage from insert 22, the notched portion 28 of rivet member 24 is much weaker than cover plate screw 17 and will break off under far less tension force than would be required to pull cover plate off of a wall or otherwise damage the hole 18 and slot 20 arrangement of the cover plate. Replacement of the notched rivet 24 is, of course, a very simple operation.
While preferred embodiments of the invention have been described herein, it will be understood that changes and additions may be made without departing from the spirit of the invention. Reference should therefore be made to the appended claims in determining the true scope of the invention.
1. A device for preventing accidental disengagement of an electrical cord from an electrical outlet comprising: a cover plate associated with the electrical outlet having a generally circular opening with one or more slots extending outwardly therefrom for releasably re ceiving a cord clamping means which is rigidly secured to the electrical cord, said cord clamping means having resilient, frusto-conical shaped insert means having a rivet-like member extending therethrough, a first end of said rivet-like member having a notch formed thereon for slidably engaging one of said slots in the cover plate in locking relationship whereby the cord clamping means is securely fastened to the cover plate, a clamp element having means cooperating with the insert means for releasably securing the clamp element to the insert means, and the clamp element having a U- shaped member with inwardly sloping side walls which may be laterally slid into a locked position about the outside of the larger diameter end of the insert means whereby disengagement of the clamp element from the insert means can only be brought about by the application of a substantial vertical pulling force.
2. A device as set forth in claim 1 wherein said clamp element further comprises a threaded member extending perpendicularly outwardly from the center portion of the top thereof for releasably engaging a generally U-shaped cord locking element having a hole therethrough so that when an electrical cord is looped about said threaded member, said cord may be rigidly locked in place by means of a threaded fastener screwed into engagement with the threaded member and thereby forcing the cord locking element to squeeze the cord between the cord locking element and the top of the clamp element.
3. A cord clamping mechanism having cord locking means thereon for rigidly attaching the mechanism to an electrical cord in releasable manner, and further having means for releasably securing the cord clamping mechanism to a cover plate associated with an electrical wall outlet, an insert means having a resilient, relatively hard, frusto-conical shape, a U-shaped clamp element with inwardly sloping side walls which may be laterally slid into a locked position about the outside of the larger diameter end of the insert means, whereby disengagement of the clamp element from the insert means can only be effectuated by the application of a substantial vertical pulling force.
4. A crod clamping mechanism as set forth in claim 3 wherein said clamp element further comprises a threaded member extending perpendicularly outwardly from the center portion of the top thereof for releasably engaging a generally U-shaped cord locking element having a hole therethrough so that when an electrical cord is looped about said threaded member, said cord may be rigidly locked in place by means of a threaded fastener screwed into engagement with the threaded member and thereby forcing the cord locking element to squeeze the cord between the cord locking element and the top of the clamp element.
5. A device as set forth in claim 4 wherein the U- shaped cord locking element has a pair of grooves extending through the underside of the top portion and parallel to the side wallswhich form the U-shape to securely engage the curvature of the electrical cord to securely hold same in locked position.
6. A device as set forth in claim 4 wherein the U- shaped cord locking element further comprises a pair of inner side walls to form channel-like passages on each side of the hole so that the cord may be passed through the channel-like passages and securely locked in position.
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|U.S. Classification||439/472, 439/371, 439/373, 174/66|