U.S. patent number 3,838,383 [Application Number 05/367,851] was granted by the patent office on 1974-09-24 for device for preventing disengagement of electrical cord from wall outlet.
Invention is credited to Alva Leroy Powell, Raymond Francis Wilbur.
United States Patent |
3,838,383 |
Wilbur , et al. |
September 24, 1974 |
DEVICE FOR PREVENTING DISENGAGEMENT OF ELECTRICAL CORD FROM WALL
OUTLET
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.
Inventors: |
Wilbur; Raymond Francis (San
Jose, CA), Powell; Alva Leroy (South San Francisco, CA) |
Family
ID: |
23448899 |
Appl.
No.: |
05/367,851 |
Filed: |
June 7, 1973 |
Current U.S.
Class: |
439/472; 174/66;
439/373; 439/371 |
Current CPC
Class: |
H01R
13/6395 (20130101) |
Current International
Class: |
H01R
13/639 (20060101); H01r 013/54 () |
Field of
Search: |
;339/75-79,82,103 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McGlynn; Joseph H.
Attorney, Agent or Firm: Hill; Robert Charles
Claims
We claim:
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 receiving 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 walls which
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.
Description
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 electrical 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 of the 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. 1 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. 1 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 14 and a hole 16 through which a threaded number 17 (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 18 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 frusto-conical 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 laterally 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 18 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
10 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 .
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