Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRICAL CORD LOCKING CONNECTOR
FIELD OF THE INVENTION
[0002] This invention relates to locking connectors for electrical extension
and power
cords to prevent separation of series-connected cords during use.
BACKGROUND OF THE INVENTION
[0003] In the construction of buildings and other structures a live electrical
outlet is
often remote from the area where workmen require electric power to operate
power tools of
various types. A typical example is a carpenter utilizing a power tool in a
multi-floor structure or
single floor areas having a long horizontal expanse. In these common
construction environments
electrical power tools are supplied with electricity using long extension
cords connected in
series, which may span long horizontal distances as well as vertically through
several floors.
When power cords separate under stress, time is lost and the broken connection
may be difficult
to locate and reestablish.
[0004] Also, in a construction environment, a series of extension cords are
often
threaded through openings, around corners and, under stress, separate at the
weakest point which
is usually where they are joined end to end. Separation at the union of two
cords or at the power
cord of a tool is not uncommon, thereby causing a complete shut down of
electrically-powered
(Docket 4181)
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equipment. Although locking devices have been proposed and used at the
interconnection
between two cords to assist in preventing separation, such devices may project
radially and thus
increase the transverse dimension of the cords at the connection, thereby
presenting an obstacle
to passing the connected cords through an opening or around a corner. When
this occurs, the
cords cannot be advanced until fed by hand through or around the turn or other
obstacle, also
resulting in lost time.
[00051 Furthermore, safety regulations in construction environments may
require that
a locking connector be used at the joinder of electrical cords in series in
order to preclude
separation under longitudinal stress and possible exposure of workers to
electric shock. This
could be caused, for example, by an uncoupled end of an extension cord being
exposed to
moisture at a construction site. This further evidences the need for an
improved locking
connector that provides a minimum of interference with handling and movement
of serially
connected electrical cords in a construction environment.
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SUMMARY OF THE INVENTION
[0006] In an embodiment of the present invention an electrical cord locking
connector
presents a streamlined profile and does not project radially outwardly at the
junction of two
interconnected cords, thereby minimizing interference in tight spaces through
which the
extension cords must be fed to service the job site. The connector joins the
ends of the
successive cords utilizing the outwardly projecting shoulder provided on the
socket end of one
cord, the socket cooperating with a latch member on the male end of a
connecting cord to lock
the two cords together at the mating ends without utilizing laterally
projecting components that
would prevent the normal feeding of the interconnected cables around corners
and through
openings and other restricted spaces.
[0007] In another aspect of the invention, a first electrical cord has an end
provided
with a plug having at least three prongs, one of which is connected to the
grounding conductor of
the cord, and a second cord has an end provided with a socket having at least
three openings
therein for receiving corresponding prongs of the first cord. The socket has
an outwardly
projecting shoulder for preventing improper mating of the prongs and openings,
and the plug has
a releasable latch member projecting therefrom which engages the shoulder when
the plug and
socket are properly mated to prevent separation of the plug and socket during
use of the cords.
[0008] In another aspect of the present invention, the latch member comprises
a plate
element having an opening therein for receiving the shoulder on the female
socket when the plug
and socket are mated and, in a further aspect of the invention, the plate
element flexes as the plug
and socket are mated to clear the shoulder until the opening in the plate
element registers
therewith.
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100091 In another aspect of the present invention a latch member is flexed as
the
cords are connected and shifts to a locking position receiving the shoulder
when the
opening in the plate registers therewith. Furthermore, in an alternative
arrangement the
latch member is provided with a lip for engaging the shoulder when the plug
and socket
are mated.
[0010] In yet another aspect of the present invention a replacement cord cap
assembly is provided with a radially outwardly projecting shoulder at the face
of the
socket adjacent the two openings in the socket that receive corresponding
current-
carrying prongs of a male plug. The shoulder is received by a latch member on
a
connecting cord to prevent separation of the plug and socket.
In a broad aspect, moreover, the present invention provides an electrical
cord locking connector comprising: first and second electrical cords, each
having a pair
of current-carrying conductors and a grounding conductor, said first cord
having an end
provided with a plug having a pair of prongs connected to respective current-
carrying
conductors, and a third prong connected to the grounding conductor thereof,
said second
cord having an end provided with a socket presenting a face having at least
three
openings therein for receiving corresponding prongs of said first cord, said
socket having
an outwardly projecting shoulder adjacent said face engageable by said third
prong for
preventing improper mating of said prongs and openings if the prongs and
openings are
improperly aligned, and said plug having a releasable latch member projecting
therefrom
and engaging said shoulder when the plug and socket are properly mated to
prevent
separation of the plug and socket during use of the cords.
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In another broad aspect, the present invention provides an electrical
connector comprising: first and second electrical connecting devices, each
having at least
a pair of current-carrying conductors, said first device having an end
provided with a plug
having at least two prongs, said second device having an end provided with a
socket
having at least two openings therein for receiving corresponding prongs of
said first
device, said socket having a laterally outwardly projecting shoulder
coextensive with said
face for preventing improper mating of said prongs and openings, and said plug
having a
releasable latch member projecting therefrom and engaging said shoulder when
the plug
and socket are mated to prevent separation of the plug and socket during use.
In another broad aspect, the present invention provides a replacement cord
cap assembly comprising: first and second electrical connecting devices, each
having at
least a pair of current-carrying conductive elements and a grounding
conductor, said first
device having an end presenting a plug having first and second prongs
connected with
respective current-carrying elements thereof, and a third prong connected with
said
grounding conductor thereof, said second device having an end provided with a
socket
presenting a generally circular face and having at least three openings
therein for
receiving corresponding prongs of said first device, a pair of said openings
being
presented by respective current-carrying elements of said second device, said
socket
having a laterally outwardly projecting shoulder coextensive with said face
adjacent said
pair of openings, and said plug having a releasable latch member projecting
therefrom
and engaging said shoulder when the plug and socket are mated, thereby
preventing
separation of the plug and socket under force until the latch member is
disengaged.
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In another broad aspect, the present invention provides an electrical cord
locking connector comprising: first and second electrical cords, each having a
pair of
current-carrying conductors and a grounding conductor, said first cord having
an end
provided with a plug having at least three prongs, one of which is connected
to the
grounding conductor thereof, said second cord having an end provided with a
socket
having at least three openings therein for receiving corresponding prongs of
said first
cord, said socket having a generally circular face presenting said openings,
and an
outwardly projecting shoulder for preventing improper mating of said prongs
and said
openings, said plug having a releasable latch member projecting therefrom and
engaging
said shoulder when the plug and socket are properly mated to prevent
separation of the
plug and socket during use of the cords, and said shoulder projecting
outwardly from said
face between two of said openings connected to respective current-carrying
conductors
and from a side of said socket opposite said grounding connector.
In another broad aspect, the present invention provides an electrical cord
locking connector comprising: first and second electrical cords, each having a
pair of
current-carrying conductors and a grounding conductor, said first cord having
an end
provided with a plug having at least three spaced prongs, a first and a second
of said
prongs being respectively connected to said pair of current-carrying
conductors, and a
third of said prongs being connected to the grounding conductor, said second
cord having
an end provided with a socket having at least three openings therein for
exclusively
receiving corresponding prongs of said first cord, said socket having an
outwardly
projecting shoulder disposed for engagement by said third prong to prevent
insertion of
said first and second prongs into said socket to thereby prevent improper
mating of said
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prongs and openings, and said plug having a releasable latch member projecting
therefrom and engaging said shoulder when the plug and socket are properly
mated to
prevent separation of the plug and socket during use of the cords.
[00111 Other advantages of this invention will become apparent from the
following description taken in connection with the accompanying drawings,
wherein is
set forth by way of illustration and example, embodiments of the present
invention.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Fig. 1 is a perspective view of one embodiment of the present invention
showing the mating ends of two extension cords connected together and locked.
[0013] Fig. 2 is a view similar to Fig. 1 but exploded to reveal the parts
prior to the
inserting the plug into the socket to connect the two extension cords
together.
[0014] Fig. 3 is a plan view of the male plug with the latch plate removed.
[0015] Fig. 4 is an exploded, side elevational view of the plug and latch
parts.
[0016] Fig. 5 is a perspective view of a second embodiment of the present
invention
showing electrical cords connected to a multiple outlet socket assembly
wherein each shoulder is
continuous over the top of the respective socket face.
[0017] Fig. 6 is a detail, plan view of a latch plate having a depending lip.
[0018] Fig. 7 is a side elevational, detail view showing the depending lip of
the latch
plate of Fig. 6 engaging a shoulder.
[0019] Fig. 8 is a partial, enlarged perspective view of the second embodiment
showing the latch plate of Fig. 6 in its locked position.
[0020] Fig. 9 is a perspective view of a third embodiment of the present
invention
showing the mating ends of two extension cords connected together and locked,
the female end
being provided with a replacement cord cap.
[0021] Fig. 10 is a view similar to Fig. 9 but exploded to reveal the parts
prior to
inserting the plug into the socket to connect the two extension cords
together.
[0022] Fig. 11 is a front view of the replacement cord cap showing the face of
the
socket.
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[00231 Fig. 12 is a side elevational view of the female replacement cord cap.
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DETAILED DESCRIPTION
[0024] Referring initially to Figs. I and 2, the mating ends of two extension
cords 10 and
12 are shown connected together in Fig. I and separated in Fig. 2 in alignment
with each other to
show the male and female parts aligned prior to connecting cords 10 and 12
together. The end of
cord 10 illustrated is provided with a male plug 14 which, in Fig. 2, is shown
aligned with but
withdrawn from a female socket 16 on the corresponding end of cord 12. It
should be
appreciated that cords 10 and 12 may extend 50 feet or more from the mating
plug and socket
illustrated in Figs. 1 and 2 where the remote end of cord 10 would be provided
with a socket, and
the remote end of cord 12 would be provided with a plug. Accordingly, at a
construction site
where extension cords are used to connect power tools to a current source,
series connected cords
may extend hundreds of feet.
[0025] Referring also to Figs. 3 and 4, plug 14 is typically provided with
three prongs
18, 20 and 22. Extension cords for a two-wire, grounded source, such as a 110
volts AC, are
illustrated herein, but it will be appreciated that the teachings of the
present invention are equally
applicable to other applications where a series of extension cords are
required to reach a site
remote from the power source. As shown in Figs. 3 and 4, a hot wire 24 is
connected to prong
18, a grounded wire 26 is connected to prong 20, and a grounding wire 28 is
connected to prong
22 in the conventional manner. The prongs 18, 20 and 22 are received by the
socket 16 at
openings 32, 34 and 36 respectively in the conventional manner.
[0026] In order to prevent inadvertent improper mating of the plug 14 and
socket 16 such
that the grounding prong 22 would not be received in opening 36, the socket 16
is typically
provided with a shoulder 38 which would prevent such a misconnection because
it would be
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engaged by the grounding prong 22 and thus the prongs 18 and 20 could not be
inserted. In the
present invention, a latch plate 40 of a resilient plastic material is secured
to the body of plug 14
by a non-metallic, self-threading screw 42 and has an opening 44 therein which
receives
shoulder 38 when plug 14 and socket 16 are united as shown in Fig. 1. The
latch plate 40 is of a
generally T-shaped configuration presenting a head 46 terminating in an
upwardly curved lip 47,
and an integral stem 48 through which the screw 42 extends to secure the latch
plate 40 to the
body of the plug 14. As the plug 14 is mated with the socket 16, the shoulder
38 engages head
46 and flexes the plate 40 upwardly as viewed in Figs. 1 and 2 until it
registers with the opening
44 and is received therein as shown in Fig. 1 in its final position. The lip
47 assists the user in
manually flexing the head 46 upwardly until it clears the shoulder 38.
Accordingly, force
applied to the cords 10 and 12 in normal use that could cause the plug 14 and
socket 16 to
separate are resisted in the present invention by the interengagement of the
latch plate 40 and
shoulder 38, which prevents separation of plug 14 from socket 16. Therefore,
the present
invention locks the two cords 10 and 12 together to prevent separation under
stress conditions. It
should be understood, however, that the latch plate 40 does not affect use of
the plug in a normal
wall socket as the latch plate can be rotated 180 degrees to a non-interfering
position.
[0027] Utilization of the self-tapping screw 42 facilitates adding the locking
feature of
the present invention to existing extension cords. Referring to Figs. 3 and 4,
a hole 50 bored in
plug 14 receives screw 42 which extends through a hole (not visible) in stem
48 and tightly
secures the latch plate 40 to the plug 14. Note in Fig. 4 that hole 50 is
between hot wire 24 and
grounded wire 26 and does not reach grounding wire 28. As seen in the exploded
view of Fig. 4,
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a washer 52 receiving screw 42 may be disposed between the stem 48 and the
underlying surface
of plug 14.
[0028] It should also be noted that the latch plate 40 prevents a two-prong
male plug
from being inser ted improperly into a socket. If this is attempted, the plate
40 engages the socket
at the projection that presents the grounding opening 36.
[0029] Referring to Figs. 5-8, the present invention may also be utilized with
extension cords having multiple socket faces, as illustrated in Fig. 5 where a
triple socket 54 on
one end of a cord 56 is illustrated. It should be noted that each socket face
57 presents a longer
upper shoulder 58 than in the single ended extension cords 10 and 12 shown in
Figs. 1 and 2. To
lock an extension cord 60 to a corresponding shoulder 58, a latch plate 62
having a depending lip
64 is utilized as best seen in Figs. 6-8. More particularly, latch plate 62
has a central opening 66
therein from which lip 64 depends at the forward end thereof, as can be seen
by a comparison of
Figs. 6 and 7. A screw 68 extends through an opening 70 in a stem portion 72
of the latch plate
62 in a manner similar to the embodiment of Figs. 1-4. Screw 68 secures latch
plate 62 to a plug
74 and is shown fully installed and locked in Figs. 7 and 8.
[0030] It should be noted that the latch plate 62 has an offset 76 that
permits the latch
to overlie the raised shoulder 58 and cause the downwardly projecting lip 64
to engage the
backside of shoulder 58 and thus lock plug 74 to the socket unit 54. As the
plug 74 is inserted,
the curved end 65 facilitates swinging the latch plate 62 to the broken line
position (Fig. 7) until
the-plug 74 is fully inserted, whereupon the plate 62 shifts.to the full line
position shown where
lip 64 engages the backside of the shoulder 58. As latch plate 62 is composed
of a resilient
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plastic, it snaps into place in the full line position shown in Fig. 7 to
prevent withdrawal of the
plug 74.
[0031] Another embodiment of the present invention is shown in Figs. 9-12 and
may
be utilized to join two end-to-end cords, one or both of which is severed or
otherwise defective
and, for example, is provided with a replacement cord cap 80 on the end of a
cord 82 connected
to a cord 84 provided with a male plug 86 having a configuration similar to
plugs 14 and 74 of
the embodiments illustrated in Figs. 1-8. As is conventional, the replacement
cord cap 80 is
provided with a clamp 88 which secures the cord cap 80 to the cord 82 and
presents, at its outer
end, a socket face 90 which, before modification in accordance with the
present invention, is of
circular configuration. Socket 90 has openings 92 and 94 therein receiving
prongs 96 and 98
respectively of plug 86 connected to hot and grounded wires respectively in
cable 84 in the
conventional manner, and an opening 100 receiving prong 102 connected to the
grounding wire.
[00321 The male plug 86 is provided with a latch plate 104 of the same
configuration
as latch plate 40 in Figs. 1-4. The latch plate 104 is secured by a screw 106
to the plug 86 and
has an opening 108 therein receiving a shoulder 110 on socket 80 having a
front surface 112
coplanar with the face 114 of socket 90. To accommodate the shoulder 110, the
socket 90 is
recessed at 116 to properly position the shoulder 110 for engagement with the
latch plate 104 as
seen in Fig. 9 where the socket and plug components 80 and 86 are mated and
locked. It should
be understood that other latch plates of similar configuration may also be
utilized, such as the
latch plate 62 illustrated in Figs. 5-7 without the offset 76.
[0033] It should be appreciated that the embodiment of the invention shown in
Figs.
9-12 provides the ability to lock two cords together when the female mating
end has been
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damaged and fitted with a replacement cord cap. This is accomplished as set
forth above by
modification of the cap by the addition of the shoulder 110 in recess 116 to
accommodate the
latch plate 104 on the male end of the connecting cord.
