Note: Descriptions are shown in the official language in which they were submitted.
CA 02680871 2011-09-23
LOCKING ELECTRICAL RECEPTACLE
BACKGROUND
A wide variety of electrical connectors are known to provide electrical
contact
between power supplies and electrical devices. Connectors typically include
prong type
terminals, generally referred to as plugs, and female connectors designed for
receiving the
prong type terminals, generally referred to as receptacles, often described as
electrical
outlets, or simply outlets. The most common types of outlets include a pair of
terminal
contacts that receive the prongs of a plug that are coupled to "hot" and
"neutral"
conductors. Further, outlets include a terminal contact that receives a ground
prong of a
plug.
The design of aforementioned plug and receptacle system generally incorporates
a
friction only means of securing the two in the mated position. The frictional
coefficient
varies depending on a variety of conditions, including, but not limited to,
manufacturing
processes, foreign materials acting as lubricants, and wear and distortion of
the
assemblies. This characteristic results in a non-secure means of
interconnecting AC
power between two devices. It is arguably the weakest link in the power
delivery system
to electrical or electronic devices utilizing the system. However, it has been
adopted
worldwide as a standard, and is used primarily due to low cost of manufacture,
ease of
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quality control during manufacture, and efficient use of space for the power
delivery it is
intended to perform.
The primary limitation of this connection technique is simply the friction fit
component. In some applications where the continuity of power may be critical,
such as
data or medical applications, a technique to secure the mated connection may
be desirable
to improve the reliability. This may especially be true in mechanically active
locations,
such as where vibration is present, or where external activity may cause the
cords
attached to the plugs and receptacles to be mechanically deflected or strained
in any
manner.
It is against this background that the locking electrical receptacle of the
present
invention has been developed.
SUMMARY
The present invention is directed to securing an electrical connection. In
some
cases, mating plug and socket electrical connections may be the least secure
liffl( in the
power delivery system. Conventionally, these connections are secured only by
means of
a friction fit. A number of factors may affect the security of this
connection. The present
invention provides a clamping mechanism whereby the very forces that would
otherwise
tend to pull the connection apart serve to actuate the clamping mechanism
thereby
securing the mated pair. The invention is of simple construction and highly
reliable in
operation. Moreover, the invention can be implemented simply in connection
with new
or retrofitted receptacle devices. Thus, the system is compatible with
existing plugs and
other infrastructure.
In accordance with one aspect of the present invention, an apparatus is
provided
for use in securing an electrical connection. The electrical connection is
formed by a
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mating structure including prongs of a male assembly and receptacles of a
female
assembly (e.g., a cord cap or outlet receptacle) where the connection is
broken by
withdrawal of the prongs from the receptacles. It is noted that a wall outlet
receptacle is
female, while cord caps may be either male or female. The apparatus includes a
clamping
element movable between a clamping configuration, where the clamping element
holds
the mating structure in a connected state, and a release configuration. An
activating
element urges the clamping element into the clamping configuration responsive
to a force
tending to withdraw the prongs from the receptacles. In this manner, a force
that would
otherwise tend to pull the connection apart will now cause the apparatus of
the present
invention to clamp the connection in a secure state.
A variety of structures are possible to implement the noted clamping
functionality.
Such structure may be associated with the male assembly and/or the female
assembly. In
one implementation, the apparatus is implemented solely in the female
assembly. For
example, the clamping element may act on one or more of the prongs of the male
assembly. In a particular implementation the clamping element acts on a ground
prong,
maintained at ground potential, such that it is unnecessary to consider
potentials applied
to the clamped prong in relation to the design of the clamping element. This
also enables
or facilitates compatibility with safety body/code regulations.
As noted above, the clamping element may include a contact surface for
contacting one of the prongs in the clamping configuration. In this regard,
the activating
element may translate movement of the prong in relation to the receptacle into
movement
of the contact surface into the clamping configuration. For example, movement
of the
prongs may be translated into rotational movement of the contact surface into
an abutting
relationship with the clamped prong. The apparatus may further include a
release element
for moving the clamping element into the release configuration. For example,
the release
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element may be operated by a user by squeezing or sliding an element of the
plug
housing.
In accordance with another aspect of the present invention, a method for using
a
securing device is provided. The securing device includes a clamping element
and an
activating element as described above. The user can activate the securing
device by
inserting the prongs of the male assembly into the receptacles of the female
assembly. In
this mated arrangement, the electrical connection is secured as described
above. The user
can further deactivate the securing device by forcing the clamping element
into the
release configuration, for example, by squeezing the housing of the male
assembly. In
this manner, the electrical connection can be simply secured and released as
desired by
the user.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1A-1C illustrate the operation of an embodiment of a clamping
mechanism.
Figures 2A-2B illustrate an embodiment of a locking electrical receptacle.
Figures 3A-3B illustrate an application for the locking electrical receptacle
shown
in Figures 2A-2B.
Figures 4A-4C illustrate an apparatus for providing a locking feature for a
standard receptacle.
Figure 5 illustrates an embodiment of a standard duplex locking receptacle.
Figures 6A-6B illustrate an embodiment of a locking receptacle that includes a
cam lock.
Figures 7A-7D illustrate an embodiment of a device for locking a mating
assembly of a plug and receptacle.
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Figures 8A-8B illustrate an embodiment of plug that includes a locking
mechanism.
Figures 9A-9B illustrate another embodiment of a plug that includes a locking
mechanism.
DETAILED DESCRIPTION
While the invention is susceptible to various modifications and alternative
forms,
specific embodiments thereof have been shown by way of example in the drawings
and
are herein described in detail. It should be understood, however, that it is
not intended to
limit the invention to the particular form disclosed, but rather, the
invention is to cover all
modifications, equivalents, and alternatives falling within the scope and
spirit of the
invention as defined by the claims.
Figures 1A-1C illustrate the operation of an embodiment of a clamping
mechanism for securing a mated electrical connection that may be included in a
locking
receptacle of the present invention. In each of the Figures 1A-1C, the bottom
portion
represents a side view of a prong 16 and a clamping mechanism 12, while the
top portion
represents a perspective view. Referring first to Figure 1A, the prong 16 of a
plug is
shown prior to insertion into a receptacle 10. The prong 16 may be a ground
prong of a
standard plug (e.g., an IEC 320 plug, a NEMA 5-15, or the like) and may be
various sizes
and shapes. Further, the receptacle 10 may be the ground receptacle of a
standard outlet
(e.g., a NEMA standard cord cap, an IEC 320 cord cap, or the like) that is
operative to
receive a standard plug. The receptacle 10 also includes the clamping
mechanism 12 that
is coupled to a pivot 14. The clamping mechanism 12 includes an aperture that
is sized to
be slightly larger than the prong 16, such that the prong 16 may only pass
through the
aperture when the length of the clamping mechanism is substantially
perpendicular to the
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length of the prong 16. That is, the design of the clamping mechanism 12 is
such that a
simple slide on and capture technique is utilized.
Figure 1B illustrates the prong 16 when inserted into the receptacle 10. As
shown,
the prong 16 passes through the aperture in the clamping mechanism 12 and into
the
receptacle 10, such that the corresponding plug and outlet are in a mated
position. The
clamping mechanism 12 further may include a stop (not shown) to prevent the
clamping
mechanism 12 from pivoting during the insertion of the prong 16. In this
regard, during
insertion of the prong 16, the length of the clamping mechanism 12 will remain
substantially perpendicular to the length of the prong 16, which permits the
passage of the
prong through the aperture of the clamping mechanism 12.
Figure 1C illustrates the gripping function of the clamping mechanism 12 in
reaction to a force on the prong 16 that tends to withdrawal the prong 16 from
the
receptacle 10. In reaction to a withdrawal of the prong 16, the clamping
mechanism 12
angularly deflects (i.e., rotates) about the pivot 14, causing the aperture in
the clamping
mechanism 12 to grip the prongs 16. Thus, the very force that tends to
withdraw the
prong 16 from the receptacle acts to actuate the clamping mechanism 12 to
engage the
prong 16, thereby preventing the withdrawal of the prong 16, and maintaining
the
electrical connection of the mated assembly. The clamping mechanism 12 may be
constructed of any suitable material, including a high strength dielectric
with an
imbedded metallic gripping tooth. An all-metallic clamping mechanism may also
be used
if the prong 16 is a ground prong.
Figures 2A-2B illustrate a cross section of one embodiment of a locking
electrical
receptacle 20. The receptacle 20 is an IEC type 320 cord cap receptacle that
includes a
locking mechanism. The receptacle 20 includes an inner contact carrier module
24 that
houses contact sockets 26 and 28. Attached to the contact sockets are wires 36
and 38
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that extend out of the receptacle 20 though a cord 34. The carrier module 24
may be
attached to a cord strain relief 32 that functions to prevent the breaking of
the electrical
connections when a force is applied to the cord 34. A spring prong retainer 40
is disposed
adjacent to a surface of the carrier module 24, and extends across a prong-
receiving
portion 44 of the receptacle 20. One end of the spring prong retainer 40 bent
around the
end of the inner contact carrier module 24, which secures it in the assembly.
The other
end is connected to a lock release grip 22. Similar to the clamping mechanism
12 shown
in Figures 1A-1C, the spring prong retainer 40 includes an aperture sized to
permit the
passage of the ground prong of a plug into the socket 26. The aperture in the
spring
prong retainer 40 may be sized to be slightly larger than one prong (e.g., the
ground
prong) in a standard plug such that the aperture may function as the clamping
mechanism
for the locking receptacle 20. The operation of the clamping feature of the
spring prong
retainer 40 is discussed in detail below.
Figure 2A illustrates the locking receptacle 20 when there is little or no
strain on
the cord 34. As shown, the portion of the spring prong retainer 40 disposed in
the prong-
receiving portion 44 of the receptacle 20 is not in a substantially vertical
position. Similar
to the operation of the clamping mechanism 12 shown in Figures 1A-1C, the
apertures of
the spring prong retainer 40 in this configuration will allow the prongs of a
plug to pass
freely into the socket 26 when the prong is inserted. This is due to the
unrestricted
change of position of the spring prong retainer 40 to the substantially
vertical position as
the prongs of a plug acts upon it.
Figure 2B illustrates the locking receptacle 20 when a force is applied to the
cord
34 of the receptacle 20 in the opposite direction of the grip release handle
30. This is the
"release position" of the receptacle 20 and is shown without the mating prongs
for clarity
of operation. Actions that initiate this position are illustrated in Figures
3A and 3B.
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Figure 3A illustrates the operation of the locking electrical receptacle 20
shown in
Figures 2A-2B. When a prong 54 of a plug 50 first enters the receptacle 20 via
an
aperture in the lock release grip 22, it encounters the spring prong retainer
40, which is
not in the perpendicular orientation at that time. Upon additional insertion,
the spring
prong retainer 40 is deflected into the perpendicular position by the force
applied to it by
the prong 54. The prong 54 passes through the aperture in the spring prong
retainer 40
and into the contact socket 26, making the electrical connection as required.
Upon release
of the insertion force, and when no axial strain is applied to the mated plug
50 and
receptacle 20, the spring prong retainer 40 is only partially displaced from
the
perpendicular axis.
Figure 3B illustrates in an exaggerated manner the condition of applying axial
tension to the cord 34 of the receptacle 20. The slight retraction motion
pulls on the
spring prong retainer 40, thereby increasing the angle of grip and subsequent
tightening of
the offset angle of the spring prong retainer 40 and prong 54. The receptacle
20 and the
plug 50 are then fully locked in this condition. Upon application of axial
tension between
the release grip handle 30 and the plug 50, the position of the spring prong
retainer 40 is
returned to the near-perpendicular position as illustrated in Figure 3A,
thereby releasing
the spring prong retainer 40 from the prong 54. Upon release, the receptacle
20 is easily
separated from the plug 50.By utilizing a clamping mechanism (e.g., the spring
prong retainer 40) that
captures the ground prong of the plug 50 only, the safety of the receptacle 20
may be
greatly improved. In this regard, the effect of the application of various
electrical
potentials to clamping mechanism of the assembly is avoided, which may
simplify the
manufacturing of the receptacle, as well as improve its overall safety.
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Figures 4A-4C illustrate a locking device 60 for providing a locking feature
for a
standard receptacle. As shown in Figure 4A, the locking device 60 includes a
top holding
member 62 and a bottom holding member 64 for positioning the locking device 60
onto a
standard receptacle. The locking device 60 also includes a portion 66 that
couples the
holding member 62, 64 in relation to each other to provide a secure attachment
to a
receptacle. The locking device 60 also includes a clamping mechanism 68 that
is coupled
to a pivot 70. The operation of the clamping mechanism 68 is similar to that
of the
clamping mechanism 12 illustrated in figures 1A-1C. The locking device 60 may
also
include a release mechanism 72 that is operative to enable a user to disengage
the
clamping mechanism 68 when it is desired to remove a receptacle from a plug.
Figure 4B illustrates the locking device 60 positioned on to a standard
receptacle
80. To facilitate the installation of the locking device 60, the holding
members 62 and 64
may be made of an elastic material such that a user may bend them outward and
position
the device 60 onto the receptacle 80. For example, the holding members 62, 64
may be
made of plastic. Further, as shown, the holding members 62, 64 are shaped such
that
once installed onto the receptacle 80, the device 60 is not easily removed
without a user
deforming the holding members 62, 64. That is, the holding members 62, 64 may
be
shaped to closely fit onto standard receptacle, such that normal movements
will not
disengage the device 60 from the plug 80.
Figure 4C illustrates the operation of the locking device 60 when the
receptacle 80
is mated with a standard plug 84. The ground prong 86 of the plug 84 passes
through an
aperture in the clamping mechanism 68 and into the receptacle 80. If a
withdrawing force
tending to break the mated connection is applied to either the cord of the
standard plug 84
or the cord of the receptacle 80, the clamping mechanism 68 will rotate,
causing it to grip
the ground to prong of the standard plug 84, thereby maintaining the
electrical
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connection. If the user desires to break the connection, the user may engage
to release
element 72, which is operative to maintain the clamping mechanism 68 in a
substantially
perpendicular position relative to the ground prong 86, thereby permitting the
prong 86 of
the standard plug 84 to be withdrawn from the receptacle 80. It should be
appreciated
that although one particular embodiment of a locking device 60 has been
illustrated, there
may be a variety of ways to implement a locking device that may be retrofitted
to a
standard receptacle that uses the techniques of the present invention.
Figure 5 illustrates an embodiment of a standard duplex locking receptacle
100.
In this embodiment, clamping mechanisms 112 and 114 are integrated into the
receptacle
100. The top portion of the receptacle 100 includes sockets 102, 104 for
receiving the
prongs 128, 130, respectively, of a standard plug 126. Similarly the bottom
portion of the
receptacle 100 includes sockets 106, 108 for receiving a second standard plug.
The
clamping mechanisms 112, 114 are each pivotable about the pivots 116, 118
respectively.
Further the receptacle 100 also includes release elements 120, 122 that are
operative to
permit a user to break the connection when desired. The operation of the
clamping
mechanism 112, 114 is similar to that in previously described embodiments.
That is, in
response to a force tending to withdraw the plug 126 from the receptacle 100,
the
clamping mechanism 112 rotates in the direction of the plug 126, and engages
the ground
prong 130, preventing the mated connection from being broken. If a user
desires to
intentionally removed the plug 126 from the receptacle 100, the user may
activate the
release mechanism 120 and withdraw the plug 126.
Figures 6A-6B illustrate side views of a receptacle 150 that includes a cam
lock
152 for locking the prong 162 of a plug 160 to preserve a mated connection
between the
receptacle 150 and the plug 160. Figure 6A illustrates the receptacle prior to
the insertion
of the plug 160, and the cam lock 152 may hang freely from a pivot 153. In
this regard,
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an end of the cam lock 152 is positioned in the opening of the receptacle 150
that is
adapted for receiving the prong 162 of the plug 160.
Figure 6B illustrates the mated connection of the plug 160 and the receptacle
150.
As shown, in the mated position the prong 162 has deflected the cam lock 152
about the
pivot 153, causing the cam lock 152 to be angled away from the plug 160 and
abutted
with the prong 162. Thus, when an axial strain is applied to the plug 160 or
the receptacle
150, the friction between the cam lock 152 and the prong 162 will tend to
force the cam
lock 152 downward toward the prong 162, which functions to retain the plug 160
in its
mated position. If a user desires to intentionally remove the plug 160 from
the receptacle
150, they may press the actuating mechanism 154, which may be operable to
rotate the
cam lock 152 out of the way of the prong 162, thereby enabling the user to
freely
withdraw the plug 160 from the receptacle 150. It should be appreciated that
the cam
lock 152 and the actuating mechanism may be constructed from any suitable
materials.
In one embodiment, the cam lock 152 is constructed out of metal, and the
actuating
mechanism 154 is constructed from an insulating material, such as plastic.
Figures 7A-7D illustrate a device 170 that may be used to secure a mated
connection between a plug and a receptacle. As shown, the device 70 includes a
top
surface 173, a bottom surface 175, and a front surface 171. The three surfaces
171, 173,
175 are generally sized and oriented to fit around the exterior of a standard
receptacle 178
at the end of a cord (i.e., a cord cap). The top and bottom surfaces 173 and
175 each
include hooks 174 and 176, respectively, that are used for securing the device
170 to the
receptacle 178 (shown in Figure 7D). The operation of the hooks 174 and 176 is
described herein in reference to Figure 7D, which shows a side view of the
device 170
when it is installed around the exterior of the receptacle 178. The hooks 174,
176 may be
bent inward towards each other, and wrapped around an end 179 of the
receptacle 178 to
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secure the device 170 to the receptacle 178. The other end of the receptacle
178 (i.e., the
end with the openings 181 for receiving the prongs of a plug) may be abutted
with the
face surface 171 of the device 170.
The device further includes tabs 172 that are used to securing the prongs of a
plug
in place. The operation of the tabs 172 is best shown in Figure 7B, which
illustrates the
device 170 when installed over the prongs 182, 184 of a plug 180. The plug 180
may be
any plug that includes prongs, including typical plugs that are disposed in
the back of
electrical data processing equipment. As shown, when the device 170 is
installed by
sliding it axially toward the plug 180, the tabs 172 deflect slightly toward
the ends of the
prongs 182, 184. In this regard, if an axial force that tends to withdraw the
device 170
from the plug 180 is applied, the tabs 172 will apply a downward force against
the prongs
182, 184. Since the openings in the device 170 are only slightly larger than
the prongs
182, 184, this downward force retains the prongs 182, 184 in their position
relative to the
device 170. Further, because the device 170 may be secured to a standard
receptacle as
illustrated in Figure 7C, the tabs 172 prevent the connection between the
receptacle 178
and the plug 180 from being broken. The device 170 may be constructed of any
suitable
material. In one embodiment, the device 170 is constructed from a semi-rigid
plastic. In
this regard, the device 170 may a single use device wherein a user must
forcefully
withdraw the installed device 170 from the prongs 182, 184 of the plug 180,
thereby
deforming the plastic and/or breaking the tabs 172. It should be appreciated
that if a user
desired to unplug the receptacle 178, they may simply unwrap the hooks 174,
176 from
the end 179 and separate the mated connection, leaving the device 170
installed on a plug.
Figures 8A-8B illustrate a plug 190 that includes a locking mechanism prior to
insertion into a receptacle 210. As shown in a simplified manner, the
receptacle 210
includes recesses 212 and 214. Most standard receptacles include a recess or
shoulder
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inside the openings that are adapted to receive the prongs of a plug. This
recess may be
present due to manufacturing requirements, such as the molding process used to
manufacture the receptacles. Further, the need to include various components
(e.g.,
electrical connections, screws, etc.) in the receptacles may cause the need
for the small
recesses.
The plug 190 uses the recess 214 to assist in creating a locking mechanism. As
shown, a hollow prong 194 (e.g., the ground prong) of the plug 190 includes a
tab 196
that is pivotably attached to an inner portion of the prong 194. A spring 198
and an
actuating mechanism 200 function together to enable the tab 196 to be oriented
in a lock
configuration (shown in Figures 8A-8B), and a release configuration. In one
embodiment, the spring 198 acts to bias the tab 198 in the release position,
which may be
a substantially horizontal position inside the prong 194. Furthermore, the
actuating
mechanism 200 may be operable to rotate the tab 196 into the lock position
(shown in
Figures 8A-8B) where the tab 196 protrudes outside the prong 194 at an angle
towards
the body of the prong 190. A user may control the actuating mechanism 200
through a
control switch 202, which may be positioned on the front of the plug 190.
Figure 8B illustrates the plug 190 when in a mated position with the
receptacle
210. As shown, the tab 196 has been placed in the lock position by the
actuating
mechanism 200. In this configuration, the tab 196 will resist any axial force
that tends to
withdraw the plug 190 from the receptacle 210. This is the case because the
recess 214
acts as a stop for the tab 196. Therefore, the plug 190 may be securely
fastened onto the
receptacle 210. When a user desires to remove the plug 190 from the receptacle
210, they
may toggle the control switch 202 on the front of the plug 190, which causes
the actuating
mechanism 200 and the spring 198 to rotate the tab 196 into the release
position.
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Figures 9A-9B illustrate another embodiment of a plug 220 that includes a
locking
mechanism prior to insertion into a receptacle 240. Similar to the plug 190
shown in
Figures 8A-8B, the plug 220 may be adapted to work with the standard
receptacle 240
that includes recesses 242 and 244. The plug 220 may include a hairpin spring
226 that is
disposed inside a hollow prong 224 (e.g., the ground prong). In a release
position, the
ends 227 of the spring 226 are disposed inside of the prong 224 and adjacent
to openings
in the prong 224. The plug 220 may further include an actuating mechanism 228,
couple
to a control switch 230 on the front of the plug 220, for biasing the spring
226 into a lock
position, where the ends 227 of the spring 226 protrude outside of openings in
the prong
224 (see Figure 9B).
Figure 9B illustrates the plug 220 when installed into the standard plug 240.
As
shown, the actuating mechanism 228 has been moved axially toward the spring
226,
causing the ends 227 to spread apart and out of the openings in the prong 224.
The
openings of the prong 224 are aligned with the recesses 242 and 244 such that
the ends of
the spring 226 are disposed in the recesses 242 and 244 when in the lock
position. Thus,
as can be appreciated, when an axial force that tends to withdraw the plug 220
from the
receptacle 240 is applied, the ends 227 of the spring 226 are pressed against
the recesses
242 and 244, which prohibits the prong 224 from being removed from the
receptacle 240.
When a user desires to remove the plug 220 from the receptacle 240, they may
operate
the control switch 230 which causes the actuating mechanism to axially
withdraw from
the spring 226. In turn, this causes the ends 227 of the spring 226 to recede
back into the
prong 224, such that the user may then easily remove the plug 220 from the
receptacle
240.
The foregoing description of the present invention has been presented for
purposes of illustration and description. Furthermore, the description is not
intended to
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limit the invention to the form disclosed herein. Consequently, variations and
modifications commensurate with the above teachings, and skill and knowledge
of the
relevant art, are within the scope of the present invention. The embodiments
described
hereinabove are further intended to explain best modes known of practicing the
invention
and to enable others skilled in the art to utilize the invention in such, or
other
embodiments and with various modifications required by the particular
application(s) or
use(s) of the present invention. It is intended that the appended claims be
construed to
include alternative embodiments to the extent permitted by the prior art.
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