Note: Descriptions are shown in the official language in which they were submitted.
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SECURE ELECTRICAL RECEPTACLE
BACKGROUND
25 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 may
30 include a terminal contact that receives a ground prong of a plug. A
variety of standards have been developed for
outlets in various regions of the world.
Regardless of the standard at issue, the design of the aforementioned most
common plug and
receptacle system generally incorporates a friction only between metallic
contacts means of securing the two in
the mated position. The frictional coefficient varies depending on a variety
of conditions, including, but not
35 limited to, manufacturing processes, foreign materials acting as
lubricants, and wear and distortion of the
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assemblies. This characteristic results in a non-secure means of
interconnecting 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 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 secure 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 link in the power
delivery system. Conventionally, these
connections are secured only by means of a manually inserted friction of
electrical contacts fit. A number of
factors may affect the security of this connection. The present invention
provides a variety of secure
mechanisms whereby the very forces that would otherwise tend to pull the
connection apart serve to actuate the
retention mechanism thereby securing the mated pair and/or where the
connection is otherwise secured in a
manner whereby a deliberate act is required to release the connection and
unintentional disconnections are thus
reduced. The present invention further provides a variety of mechanisms
whereby the user can manually elect
to actuate the retention 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 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 generally
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.
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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 life safety/ code
regulations. However, it will be appreciated that other prongs may be
additionally or alternatively engaged.
As noted above, the clamping element may include one or more contact surfaces
for contacting one or
more of the prongs in the clamping configuration. In this regard, the
activating element may translate movement
of the prongs in relation to the receptacle into movement of the contact
surface or surfaces 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. Alternatively, a
withdrawal force exerted on the
plug/prongs may cause elongate contact surfaces to engage opposing side of the
prong. The apparatus may
further include a release element for moving the clamping element into the
release configuration. For example,
the release element may be operated by a user by squeezing, sliding, pulling
or pushing an element of the plug
housing. In one implementation, a cord cap housing may be formed in two
sections that are interconnected for
sliding relative to each other in telescoping fashion. The clamping element
can then be engaged manually by
the user or automatically in response to a tension on the cord or section of
the cord cap hence engaging the
lock, and later released by selecting and sliding the corresponding section of
the sliding housing section to the
release position. It will be appreciated that the housing section can thus be
readily accessed to release the
clamping element even in crowded environments (e.g., in a data center rack).
Moreover, the housing section to
be gripped for releasing the clamping element may be color coded or otherwise
conspicuously identified to assist
users. Also, a variety of methods can be used to indicate if the clamping
mechanism has been released at one
time.
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 or by separately manipulating a locking actuator. 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 or
sliding the housing section or actuating a tab or button or knob that is part
of the cord cap or other means. In
this manner, the electrical connection can be simply secured and released as
desired by the user.
In accordance with a further aspect of the present invention, the release
tension of a locking electrical
receptacle can be selected in relation to a defined standard so as to avoid
damage to a cord cap, cordage or
plug or to meet a standard in relation thereto. In this regard, the release
tension of the locking receptacle can be
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adjusted by varying, among other things, the geometry, thickness, material
qualities and detail shaping of a
clamping mechanism. It has been recognized that setting the release tension
too high could result in damage to
the receptacle housing, cordage or a mating plug which could, in turn, result
in exposed wires and a safety
hazard. Moreover, standards may be defined for release tension in relation to
such concerns or others. An
associated methodology in accordance with the present invention involves
providing a locking electrical
receptacle with a clamping element; determining a release tension limit for
the receptacle in relation to a
standard for safe operation of the electrical connection; determining a
specification or setting of the clamping
element to conform to the release tension limit; and constructing, or setting
an adjustment mechanism of, the
locking electrical receptacle in accordance with the specification or setting.
For example, the release tension
can be coordinated with a structural specification of an end cap or plug or
cord so as to substantially ensure that
the end cap or plug or cord will not break or fail due to strain associated
with excessive release tension. In this
manner, the characteristics of the locking electrical receptacle can be varied
to address safety concerns or
related standards or to match a desired setting of a user (which may change
from time-to-time or depending on
the application at issue).
In accordance with a still further aspect of the present invention, a strain
relief mechanism is provided in
connection with a locking mechanism of an electrical connection. As noted
above, a potential concern in relation
to a locking electrical connection is damage to an end cap, plug, cord or
other structure, particularly where a high
relief tension is desired. To alleviate such concerns, a strain relief
structure is provided for transmitting a strain,
associated with operation of a clamping mechanism for holding mating
connection structure in a connected
state, from the clamping mechanism to a power cord or other structure. For
example, a clamping mechanism
may be provided in a receptacle end cap for engaging one or more prongs of a
plug. In such a case, strain relief
structure may be provided that extends across the length of the end cap from
the clamping mechanism for
attachment to the power cord, e.g., by crimping, welding or otherwise joining.
Alternatively, the strain may be
transmitted to other structure separate from a receptacle/plug, such as a wall
receptacle support structure. The
strain relief mechanism thereby avoids hazards associated with undue stress on
the end cap or other structure
and reduces or substantially eliminates the need for other structural
enhancement of the end cap or other
structure.
In accordance with another aspect of the present invention, an apparatus is
provided for use in securing
an electrical connection. The electrical connection is formed by a 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 generally
female, while cord caps may be either male or female. It also noted that
receptacles used for electronic data
processing (EDP) equipment are.generally male. That is, the housing of such
receptacles receives a portion of
the housing of a plug, but the connection prongs are in the receptacle, not
the plug. The apparatus includes a
retention element movable between a secured configuration, where the retention
element holds the mating
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structure in a connected state, and a release configuration. An activating
element urges the retention element
into the secured configuration. It may be designed to be 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 retain the connection in a
secure state.
A variety of structures are possible to implement the noted retention
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 male assembly. For example, the retention element
may act on one or more surfaces
of the female assembly. In a particular implementation the retention element
acts on two or more surfaces of the
female receptacle. Upon the application of a force that would tend to pull the
connection apart, a component of
the male assembly is moved to press or press more firmly on the walls of the
female assembly via a mechanism
activated by such force. The part of the male assembly that contacts the
surfaces of the receptacle may
incorporate a suitable component made of materials (for example high co-
efficient of friction elastomers) which
may be specifically chosen and shaped to optimize its function or be a hybrid
design that combines yet other
materials such as metal inserts or pieces to best perform its function. The
design may utilize another material
component such as a lever, cam or ramp with suitable mechanical and frictional
properties. The elastomer or
other component is forced into high pressure contact with the walls of the
receptacle by the mechanism. The
contacting surface may be equipped with a high friction material to increase
the mechanical friction interlock of.
the male assembly and the receptacle. The elastomer can be shaped in a variety
of shapes. For example, an
elastomeric ring may extend peripherally around the interface between the mail
assembly and the female
assembly or receptacle. However, the contact surface need not extend across
the entire interface, but may be
present only at one of more sections of the interface. Generally, it may be
useful to provide the contact surface
on opposing surfaces so that they balance and act against one another. The
location of these surfaces may be
selected to avoid interfacing structure of the male and/or female assemblies
and/or to exert pressure on
structurally stronger or reinforce surfaces. In one embodiment, contact
surfaces or gripping elements provided
at the corners of a generally rectangular interface. In this manner the
security of the connection can be greatly
increased, so that the connection will maintain its integrity in a
mechanically active environment and resist
inadvertent disconnection up to a desired or preset pull force. This also
enables or facilitates compatibility with
life safety/ code regulations.
As noted above, the retention element may include one or more contact surfaces
for contacting one or
more surfaces of the mating receptacle (which can be either male or female,
for example IEC C13 and C14
plugs and receptacles as used in plugstrips and EDP equipment power inputs) in
the retained configuration. In
this regard, the activating element may translate movement of the plug in
relation to the receptacle into
movement of the contact surfaces into the retained configuration. For example,
movement of the plug may be
translated into movement of the contact surfaces into an abutting relationship
with one or more of the receptacle
surfaces. The apparatus may further include a release element for moving the
retention element into the release
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configuration. For example, the release element may be operated by a user by
squeezing, sliding, twisting,
pulling or pushing an element of the plug housing. In one implementation, a
cord cap housing may be formed in
two sections that are interconnected for sliding relative to each other in
telescoping fashion. The outer housing
may be moved by the action of the user pushing, pulling or squeezing directly
on the housing or by the user
manually operating a manual actuation element that moves the outer housing
between the secured and released
configurations. The retaining element can thus be engaged manually by the user
or automatically in response to
a tension on the cord or section of the cord cap hence engaging the retention
function. It can later be released
by selecting and moving the corresponding section of the sliding housing
section to the release position or
moving the manual actuation element to the release position. It will be
appreciated that the housing section or
manual actuation element can thus be readily accessed to release the retention
element even in crowded
environments (e.g., in a data center rack). Moreover, the housing section or
Manual actuation element to be
gripped for releasing the retention element may be color coded or otherwise
conspicuously identified to assist
users in identifying if the mechanism is currently secured or unsecured. It
can also be textured or shaped to
assist the user in gripping it. Also, a variety of methods can be used to
indicate if the retention mechanism has
been released at least one time.
In accordance with another aspect of the present invention, a method for using
a securing device is
provided. The securing device includes a retaining element and an activating
mechanism (either automatic or
manual) as described above. The user can activate the retaining element by
separately manipulating a locking
actuator after insertion. In this mated arrangement, the electrical connection
is secured as described above.
The user can further deactivate the securing device by forcing the activating
element into the release
configuration, for example, by squeezing the housing of the male assembly or
sliding the housing section or
actuating a tab or button or twisting a nut or knob that is part of the cord
cap or other means. The methods that
utilize a nut (screw) or knob (swash plate or other method) to actuate the
retaining element can incorporate a
simple ratchet mechanism (that allows a nut or knob to be turned in either
direction in small indexed increments)
to allow the user to select and adjust the tightness of the nut or the knob
and in turn adjust the force required to
separate the secured connection. Also, the size and shape of the nut or the
screw, and the mechanical
advantage that they deliver can be selected to make it difficult or impossible
for an average user to damage the
securing mechanism or the plug or receptacle by excessive manually applied
force. This feature offers a
programmable release mechanism, where the force required to break the
connection can be "programmed" into
the design and further made adjustable and selectable by the user within a
desired range of connection retention
force values. Also, the characteristics of the mechanism, combined with the
geometry and range of motion
offered by the ratcheted nut or knob can be used to compensate for a wide
range of dimensional tolerances as
are commonly found in the production plugs and receptacles. In this manner,
the electrical connection can be
simply secured and released as desired by the user while preventing damage to
the components of the
connected plug and receptacle.
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In accordance with a further aspect of the present invention, another method
for using a securing
mechanism is provided. In another implementation of the retention mechanism,
the apparatus can be
implemented in either the female or the male assembly. One or more retention
tabs or hooks that can be
appropriately shaped and of variable width can be provided. They can be made
of appropriate materials and
geometry. The retention tabs or hooks will engage in one or more openings,
e.g., slots, that are provided in the
matching receptacle at an appropriate location. Most commercially available
receptacles often have such an
opening available, it is part of a finger in the receptacle that allows the
receptacle to snap into a panel. These
openings are not always provided, but these receptacles could easily be
modified to provide such openings in
every model, both single receptacle and multiple receptacle molded assemblies.
Such modifications would be
simple and low cost to make and also would likely be quickly certified by
safety certification organizations such
as Underwriters Laboratories. Therefore this retention mechanism may be easy
and quick to bring to market
therefore having significant commercial and economic value. The tab or hook
retention mechanism can be
designed to either engage automatically if an opening is available (e.g., due
to a spring loaded configuration) or
manually using a user activated manual mechanism. It can be activated and/or
released using a variety of
methods that are described herein, e.g., for mechanically withdrawing the
hooks from the openings. It could also
be combined with other retention mechanisms that are described herein.
In accordance with a further aspect of the present invention, the release
tension of a secure retention
electrical plug or receptacle can be selected in relation to a defined
standard so as to avoid damage to a cord
cap, cordage or plug or to meet a standard in relation thereto. In this
regard, the release tension of the secure
receptacle can be adjusted by varying, among other things, the geometry,
thickness, material qualities and detail
shaping of a retention mechanism. Further, a programmable release tension
mechanism can be incorporated as
part of the design of the retention mechanism. It has been recognized that
setting the release tension too high
could result in damage to the receptacle housing, cordage or a mating plug
which could, in turn, result in
exposed wires and a safety hazard. Moreover, standards may be defined for
release tension in relation to such
concerns or others. An associated methodology in accordance with the present
invention involves providing a
secure electrical receptacle with a retention element; determining a release
tension limit for the receptacle in
relation to a standard for safe operation of the electrical connection;
determining a specification or setting of the
retention element to conform to the release tension limit; and constructing,
or setting an adjustment mechanism
of, the secure electrical receptacle in accordance with the specification or
setting. For example, the release
tension can be coordinated with a structural specification of an end cap or
plug or cord so as to substantially
ensure that the end cap or plug or cord will not break or fail due to strain
associated with excessive release
tension. In this manner, the characteristics of the secure electrical
receptacle can be varied to address safety
concerns or related standards or to match a desired setting of a user (which
may change from time-to-time or
depending on the application at issue).
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In accordance with a still further aspect of the present invention, a strain
relief mechanism is provided in
connection with a retention mechanism of an electrical connection. As noted
above, a potential concern in
relation to a secure electrical connection is damage to an end cap, plug, cord
or other structure, particularly
where a high relief tension is desired. To alleviate such concerns, a strain
relief structure is provided for
transmitting a strain, associated with operation of a clamping mechanism for
holding mating connection structure
in a connected state, from the retention mechanism to a power cord or other
structure. For example, a retention
mechanism may be provided in a receptacle end cap. In such a case, strain
relief structure may be provided
that extends across the length of the end cap from the retention mechanism for
attachment to the power cord,
e.g., by crimping, welding or otherwise joining. Altematively, the strain may
be transmitted to other structure
separate from a receptacle/plug, such as a wall receptacle support structure.
The strain relief mechanism
thereby avoids hazards associated with undue stress on the end cap or other
structure and reduces or
substantially eliminates the need for other structural enhancement of the end
cap or other structure.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1A-1C illustrate the operation of an embodiment of a clamping
mechanism in accordance with the
present invention.
Figures 1D-1F and 1H-1J illustrate the operation of another embodiment of a
clamping mechanism in
accordance with the present invention.
Figure 1G illustrate the operation of another embodiment of a clamping
mechanism in accordance with
the present invention.
Figures 2A-2B illustrate an embodiment of a locking electrical receptacle in
accordance with the present
invention, using the clamping mechanism described in Figures 1A-1C.
Figure 2C illustrates an embodiment of a locking electrical receptacle in
accordance with the present invention,
using the clamping mechanism described in Figures 1D-1F, 1H-1J or 1G.
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 in
accordance with the present invention.
Figure 5 illustrates an embodiment of a standard duplex locking receptacle in
accordance with the =
present invention.
Figures 6A-6B illustrate an embodiment of a locking receptacle that includes a
cam lock in accordance
with the present invention.
Figures 7A-7D illustrate an embodiment of a device for locking a mating
assembly of a plug and
receptacle in accordance with the present invention.
Figures 8A-8C illustrate an embodiment of plug that includes a toggle locking
mechanism in
accordance with the present invention.
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Figures 9A-9B illustrate another embodiment of a plug that includes a
divergent spring tip locking
mechanism in accordance with the present invention.
Figures 10A-10B illustrate a further embodiment of an end cap incorporating a
locking mechanism in
accordance with the present invention.
Figures 11A-11B illustrates an alternative shaping of a spring prong retainer
in accordance with the
present invention that enables improved cord retention and increased overall
strength.
Figure 12 is a perspective view of an alternative embodiment of a spring prong
retainer in accordance
with the present invention.
Figures 13A-15B show an alternative embodiment of a locking spring prong
retainer electrical
receptacles and spring prong retainers in accordance with the present
invention.
Figures 16A-18D illustrate the operation of an embodiment of a retention
mechanism in accordance with the
present invention.
Figures 19-22 illustrate the operation of another embodiment of a retention
mechanism in accordance
with the present invention.
Figures 23-24 illustrate an embodiment of plug that includes a tab or hook
retention mechanism in
accordance with the present invention.
Figure 25 illustrates an embodiment of a mechanism that insures positive
retraction of the outer shell
when the locking nut is turned to the release position in accordance with the
present invention.
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 or other receptacle(s), 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
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clamping mechanism is substantially perpendicular to the 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
spring 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.
In this regard, an all-metallic clamping mechanism may be used, e.g., for
other prongs, though modifications
may be required to obtain approval by underwriting bodies.
Figures 1D-1F & 1H-1J illustrate the operation of another 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 illustrations 500-505 of Figure 1D, the top row of figures
represents the end-on views of the clamping
mechanism and the bottom row represents side views of the clamping mechanism
with an electrical contact
prong in the states of: 1) disengagement 500 , 2) being inserted 501, 3) fully
inserted 502, 4) fully inserted under
tension 503, 5) being released 504 and 6) during contact removal 505. The
example clamping mechanism as
shown in Figure 1E has two channels 606 that grip the sides of the contact and
cross-link springs 603
connecting the channels. It should be noted that the clamping mechanism can
act as both the electrical contact
and clamping mechanism together or can be only a clamping mechanism that is
integrated with a separate
electrical contact. Figures 1H-1J shows the clamping mechanism acting as both
the electrical contact and
clamping mechanism and Figure 1F shows a clamping mechanism that is suitable
for use with a separate
electrical contact. Details of Figure 1H include the gripping channels 902,
the cross-link springs 901, the
integrated electrical conductor crimp 903, the release shaft 904 and the
release shaft contact nub 905. Possible
instantiations can be made of one suitable material or several materials (for
example steel and copper) to
optimize the functionality of the clamping mechanism, electrical and
mechanical properties, ease of manufacture
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and cost. The materials can joined together or secured to function together by
any suitable means such as
mechanical interlock, fasteners, gluing, etc. as is needed to optimize their
function and minimize their cost.
A possible example of this would be a clamping mechanism that is also an
electrical contact made of -
annealed brass or phosphor bronze or other suitable material. Due to the
expansion characteristics of the
chosen materials, the expansion associated with heating of the retainer
contact (receptacle) and more
specifically the expansion of the cross-link springs, from any resistance in
the connection of it to the inserted
electrical prong (Note that the prong could be different shapes, it could be a
pin for example), will result in
progressive tightening of the grip function. Even if the receptacle is not
'locked" to the prong upon initial
insertion; e.g. no extraction force is applied to tighten the gripping
mechanism, and the only bearing force
applied to the contact surfaces is the force of the cross-link spring action,
when current is applied, the resistance
at the junction of the socket and prong will result in some degree of heating.
If the resistance is high enough,
say the prong is under-sized, or damaged and not uniformly in contact with the
channels, the temperature of the
assembly will start to rise. In addition, the electrical connection between
the channels, that is the channel that is
connected directly to the incoming wire and the opposing channel connected via
the cross-link springs, can be
manipulated in cross section to have additional heating at higher current
levels such that more heating is
occurring in the cross-link springs than elsewhere. In any case, heating of
the cross-link springs will result in
expansion. Since the heat sinking is largely via the inserted prong, and
subsequently the wire of the associated
connection, the temperature of the cross-link spring will be higher than the
prong temperature average. Hence
slightly less expansion of the prong will be present. At some point the
differential will allow the natural tendency
of the spring loaded and racked socket receptacle to overcome the molecular
lock (static friction) between the
channels and the edges of the prong. The channels will move slightly with
regards to the prong and a new
engagement will be established. At this point, the electrical resistance will
drop due to the newly established,
and slightly tighter connection between the channels and the prong, and the
whole thing will start cooling. Now,
the cross-link springs will shorten, and the force exerted on the bearing
points between the channels and the
prong will increase dramatically because the tangential force, similar to the
force applied when pull-out force is
applied, and the electrical connection will be re-established much more
effectively. This in turn will reduce the
resistance further and effectively "lock" the receptacle to the prong, and
guarantee superior electrical connection,
even with imperfect mating surfaces. It is a re-generative condition that is
responsive to poor connections, and
tends to self-heal a poor electrical connection.
Figure 1E shows the mechanical properties of the clamping mechanism. An
electrical contact 600 (or
other plug structure) is inserted into the clamping mechanism 601. The
dimensions of the clamping mechanism
are set so that the contact will spread the clamping mechanism open. In this
regard, the forward end of the
clamping mechanism (the end that is first contacted by the electrical contact)
may be flanged outwardly to
capture the contact and facilitate spreading of the clamping mechanism. This
spreading action is shown in
Figure 1D 511. The transverse cross-link springs 603 act to resist the
spreading open of the clamping
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mechanism. This insures that the edges of the electrical contact 600 are
biased to touch the channels at defined
contact points 609. Differently shaped electrical contacts and/or clamping
mechanisms would have different
contact points and/or surfaces. In the illustrated embodiment, the contact
points/surfaces where clamping occurs
are primarily or exclusively on the top and bottom surfaces of the prong,
rather than on the side surfaces where
electrical connections are typically made. This may be desirable to avoid
concerns about any potential
degradation of the electrical contact surfaces thought it is noted that such
degradation is unlikely given that the
clamping forces are spread over a substantial length (and potentially width of
the contact. Once the electrical
contact prong 600 has been inserted into the clamping mechanism 601, any
pulling force F(pull) 604 that acts to
remove the prong 600 from the clamping mechanism 601 will result in a clamping
force F (grip) 605 being
exerted on the sides of the prong 600. The clamping force is generated by the
action of the transverse cross-link
link springs pulling on the channels 606 on each side of the clamping
mechanism such that the channels are
urged towards one another. The relationship of the forces will be generally
F(grip)= F(pull)/tangent (angle theta).
Thus, the clamping force F(grip) will increase faster than the force F(pull)
that is acting to remove the prong 600
from the clamping mechanism 601. Therefore the grip of the clamping mechanism
601 on the prong 600 will
become more secure as the force trying to extract the prong 600 increases.
Once the gripping mechanism has
been actuated by a pull force 604, friction will tend to keep the gripping
mechanism tightly engaged. To release
the gripping mechanism, the release rod 607 is pushed, generating a force
F(release) 608. This force will
decrease the angle theta and urge the channels away from one another, rapidly
decreasing the gripping force
F(grip) 605 and allowing the prong 600 to be easily removed from the gripping
mechanism 601. The release
force 608 needed to effect release can be very small.
In one possible embodiment, associated with a standard NEMA C-13 outlet, the
transverse cross-link
spring may be formed from copper or a copper alloy and have a thickness of
about 50/1000 75/1000 of an
inch. In such a case, the curve 602 may be generally circular in shape with a
radius of curvature of about
75/1000 of an inch. The curve 602 may extend into the cross-link spring 603 so
that a narrowed neck, from
radius-to-radius, is formed in the cross-link spring 603. Such a curve 602, in
addition to affecting the operational
properties of the gripping mechanism as may be desired, avoids sharp corners
that could become starting points
for cracks or accelerate metal fatigue. The neck also helps to better define
the pivot point of the cross-link
spring 603 in relation to the channels as may be desired. It will be
appreciated that specific operational
characteristics, such as (without limitation) the amount of any slight
movement allowed before locking, the total
amount and location of clamping forces exerted on the prong, the force level
(if any) where the clamping
mechanism will release, and the durability of the clamping mechanism for
frequent cycling, may be application
specific and can be varied as desired. Many other configuration changes and
construction techniques are
possible to change these operational characteristics. For example, the cross-
link spring (or a portion thereof)
may be twisted (e.g., at a 900 angle to the plane of stamping of the material)
to affect the pivot point and flexing
properties of the spring as may be desired.
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The choice of material, thickness and geometry and shaping of the apparatus
affect the operational
properties of the gripping mechanism 601. The transverse cross-link springs
can have their spring constant
affected by all of these variables. For example the radius, location and shape
of the curve 602 and the thickness
of the neck of the transverse cross-link spring 603 can be varied to achieve
differing values of spring constants.
This can be desirable to optimize the pre-tension gripping force exerted by
the spring on a contact inserted into
the retention mechanism or the range of contact sizes the gripping mechanism
will function with. Note: The pre-
tension gripping force is defined as the gripping force exerted on the contact
600 by the action of the transverse
cross-link springs 603 before any pull force 604 is placed on the contact.
Referring to Figure 1G another possible instantiation is shown. In this
instantiation, the operation of the
mechanism is similar to the_operation described in (1-D through 1F). As
tension is applied to the assembly
between Force Pull 710 on the prong 706 and the Counter-Force Pull 711,
bearing forces at the contact points
(703,707) of the channels (704, 705) and the inserted contact prong 706 (note
that the prong could have
different shapes, it might be a pin for example) increase exponentially,
resulting in immediate capture of the
prong by the channels. As F Pull 710 increases, the tension in the cross-link
springs 701 continue to increase as
well. The cross-link springs are crescent shaped in this instantiation as
opposed to the straight springs described
in Figures 1D-1F & 1H-1J. The crescent shape allows the cross-link springs to
now have two actions. First, they
have a spring action at the connection point to the channels (704, 705) and
secondly they have a spring action
along the long axis of the cross-link spring (701). The addition of the spring
action along the long axis allows the
cross-link spring to have a predictable ability to lengthen, or stretch. As F
Pull 710 continues to increase, the
tension in the cross-link springs 701 continue to increase to a point where
the cross-link spring begins to stretch
along its long axis. At this point, the relationship between the F Pull 710
applied and the resulting grip forces at
the contact points (703,707) of the channels (704, 705) and the inserted
contact prong 706 ceases to increase.
Now, increasing Force Pull 710 results in overcoming the friction at the
contact points 703,704, and the contact
pin 706 will move in relationship to the channels (704, 705) and hence the
gripping mechanism 700. If Force Pull
710 is maintained, the contact prong 706 will become extracted from the
channels (704, 705) completely. This
condition allows the assembly 700 to have a predictable point in tensile
relationships where a plug and
receptacle can be separated without damage to either principal component, the
prong or the gripping
mechanism (which can be a gripping mechanism that is also an electrical
contact or a separate gripping
mechanism with integrated electrical contact as noted earlier).
Referring again to Figure 1D, the prong 530 of a plug is shown prior to
insertion into a receptacle with
an electrical contact represented by 510. . The prong 530 may be a ground
prong or other 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 containing the electrical contact 510 may be the ground receptacle
or other receptacle(s), 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 includes the clamping mechanism 520 and may
utilize more than one clamping
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mechanisms in one receptacle. The design of the clamping mechanism 520 is such
that a simple slide on and
capture technique is utilized.
Other clamping mechanisms are possible in accordance with the present
invention. For example, a
wire mesh, formed and dimensioned so as to receive a contact, prong or other
plug structure (collectively,
"contact") therein, may be utilized to provide the clamping mechanism. The
wire mesh is dimensioned to
frictionally engage at least one surface of the contact when plugged in. When
a force is subsequently exerted
tending to withdraw the contact from the receptacle, the wire mesh is
stretched and concomitantly contracted in
cross-section so as to clamp on the contact. A Kellem-style release mechanism
may be employed to relax the
weave of the mesh so that the contact is released. Such a gripping mechanism
may be useful, for example, in
gripping a cylindrical contact.
Figures 2C illustrate a cross section of one possible embodiment of a locking
electrical receptacle 820.
The receptacle 820 is an IEC type 320 cord cap receptacle that includes one or
more gripping mechanisms 828.
The receptacle 820 includes an inner contact carrier module 824 that contains
a gripping mechanism and
electrical contacts 826 and 828. Attached to the gripping mechanism and
electrical contact sockets are wires
836 and 838 that extend out of the receptacle 820 though a cord 834. The
carrier module 824 may be attached
to a cord strain relief 832 that functions to prevent the cord from separating
from the cord cap or otherwise
resulting in damage to the assembly when a force is applied to the cord 834.
Figure 2C demonstrates one
possible release mechanism actuation method. Specifically, the receptacle 820
is formed in telescoping fashion
with a shell 822 that slides on the carrier module 824 and strain relief 832.
A protrusion 850 on shell 822
engages a release 851 of mechanism 828 such that sliding the shell 822 engages
the mechanism 828 to its
release configuration. The clamping mechanisms described in Figures 1D-1J can
be combined many of the
other release mechanisms described in the incorporated filings.
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 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 cord from
separating from the cord cap or
otherwise resulting in damage to the assembly 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 is bent around the
end of the inner contact carrier
module 24, which secures it in the assembly (underneath the over-molded
material 32).
Alternatively, the spring prong retainer 40 may be secured to the inner
contact carrier module 24 by a
screw or other fastener, and/or embedded in the module 24. A section of the
spring prong retainer 40 that is
'embedded in the module 24 or alternatively secured in the cord cap via over
molded material may be configured
(e.g., by punching a hole in the embedded section and/ or serrating the edges
or otherwise shaping it) to
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enhance the anchoring strength in the embedded section. The other end of the
spring prong retainer 40 is in
contact with a telescopic 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. It can be appreciated that prongs with different
cross-section shapes, for example
round prongs, can use the retention mechanism described herein, with a
suitable modification of the aperture
shape and geometry of the spring prong retainer. Such modifications may be
specific to the various shapes of
the cross section of various prong types. Such variations will function in
substantially the same manner as the
retention mechanism described herein. The spring prong retainer 40 may further
be shaped and constructed, as
will be discussed in more detail below, to inhibit contact with other prongs
and provide a desired release tension.
Moreover, the retainer 40 may be retained within a recessed channel formed in
the module 24 to further inhibit
transiting or side-to-side displacement of the retainer 40. 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.
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 401s deflected into the
perpendicular position by the force applied
to it by the prong 54. The prong 54 then 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. It is noted that there is
little separation between the forward-most
surface of the plug 50 and the end of the receptacle of carrier module 24
adjacent the plug 50 in this connected
configuration, i.e., the prong extends to substantially the conventional
extent into the receptacle.
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Figure 3B illustrates in an exaggerated manner the condition of applying axial
tension to the cord 34 of
the receptacle 20. A 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.
Because the release grip handle 30 is
mounted to slide in telescoping fashion with respect to the carrier module 24
and can be gripped for prong
release from the top or sides, the locking mechanism can be easily released
even in crowded or space limited
environments such as in data centers.
Figures 13A-13C illustrate an alternative spring prong retainer. In the
embodiment described above
and illustrated by Figs. 1A through 3B, the retention gripping points are
along the flat, or semi-flat surfaces of the
narrow axis of the prong. The apertures are rectangular in shape and the top
and bottom of the rectangle
comprise the contact locations on the prong. Forces applied to those contact
points are limited to the
relationship of the precision of the prong dimensions to the hole dimensions.
In the embodiment of Figure 13A,
the aperture has a rectangular top and a bottom half that narrows down or
tapers. This design of aperture
contacts the prong at three locations 1100, 1101, 1104 (see Figure 13A ¨
Exaggerated View), on the top of the
prong and on each of the sides at the bottom.
A significant increase in the gripping force is possible due to the
amplification of the pull torque via not
only the angular displacement of the spring prong, but also the wedging effect
at the two adjacent contact points
1100, 1101 at each corner of the narrow axis of the mating prong 1103. As pull
force is exerted on the hook tab
1106 of the spring retainer 1110, an initial action occurs as described for
the spring prong retainer in Figures 1A
thru 1C. After the initial contact is made at points 1100, 1101, 1104 during
the attempt to withdraw the mating
prong 1103, the forces applied to the mating prong 1103 are amplified by the
inclined planes of the bottom of the
slot 1100 1001. The tension force formed in the early stage of gripping by the
axial displacement of the spring
prong retainer 1110 about the fulcrum point 1105 is amplified greatly to apply
a compressive force at the contact
points of the mating prong 1103 and the spring prong retainer bottom contact
points 1100 and 1101. This force
is multiplied by about 10 to 1 due to the tension amplification of the spring
prong retainer 1110 about the fulcrum
1105. A total force amplification of about 80 times can be achieved by this
method. It should be appreciated
that by adjusting the angles of the inclined planes 1100 and 1101, and the
geometry of metal 1104 forming the
fulcrum 1105, that various amplifications of force can be achieved. It should
also be appreciated that by varying
the amplification force, the spring prong retainer can be tuned to optimally
engage with a variety of mating prong
materials and finishes.
Due to this amplification, and the relatively small contact area between the
spring prong retainer,
inclined planes 1112 (Figure 13C) 1110, 1101 and the mating prong 1103, forces
at least as high as 30,000
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pounds psi (30Kpsi) are possible, thus ensuring positive gripping of the
mating prong 1103. It should be
appreciated that use of this alternate method of mating prong capture is also
more tolerant of manufacturing
variances in the prongs.
Figure 13B illustrates the release methodology for this alternate spring prong
retainer. It is similar to
that of the spring prong retainer previously described. As release force is
applied to the end of the spring prong
retainer 1111 by the face of the outer shell 1116, the surface of the spring
prong retainer 1110 becomes more
perpendicular to the mating prong 1103. In turn, the point of contact at the
fulcrum 1105 is disengaged and the
mating prong would normally be free to be extracted, as described for spring
prong retainer 40 of previous
embodiments. However, at this point the lower contact points (illustrated in
Figure 13A) 1100, 1101 have the
mating prong 1103 captured between them, and likely a small deflection of the
metal of the mating prong 1103
has occurred at those points. The mating prong 1103 is therefore probably not
yet released. As the outer shell
1116 compresses the face of the spring prong retainer 1110, the molded-in ramp
in the outer shell 115 begins to
push the spring prong retainer down and in turn pushes the lower contact
points 1100 and 1101 (illustrated in
Figure 13A) down off of the mating prong 1103. Eventually the entire assembly
is disengaged from the mating
prong 1103.
It should be appreciated that the shape of the spring prong retainer
(illustrated in Figure 13A)
contributes to the disengagement characteristics as well. The shoulders of the
spring prong retainer 1107 are
placed such that, upon force being applied to the spring prong retainer to
release, the shoulders contact the
interior surface of the outer shell 1116. Continued rotation of the face of
the spring prong retainer closer to
perpendicular to the mating prong 1103 results in the entire face of the
spring prong retainer 1111 to be forced
down. This action, in conjunction with the action of the ramp cast into the
outer shell 1115 results in positive
down force on the spring prong retainer disengaging the lower contact points
1100 and 1101 (illustrated in
Figure 13 A) from the mating prong 1103.
Figures 14A-15B illustrate an alternate capture mechanism. Figure 14C
illustrates the principal
mechanical components of the capture mechanism. A saddle and strain relief
component 1401 is placed into
the plastic connector carrier of the injection molded receptacle. A capture
toggle 1402 is inserted into the two
holes at the end of the saddle 1401. The opposite end of the saddle and strain
relief component 1401 is the
crimp ring that clamps around the cord end just beyond the start of the outer
jacket or other suitable location
depending on the design of the cord. It will be appreciated that if, e.g., for
ease of manufacturing, it is designed
to make the strain relief and clamping mechanism from different materials,
such as metals of different properties,
than the carrier or other cord attachment mechanism, this can easily be done,
by separating the attachment =
method to the cord, such as a crimp ring from The strain relief piece and then
connecting them mechanically. It
should be appreciated that the strain relief mechanism described herein can be
used with the two additional
retention mechanisms described earlier.
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Figure 14A illustrates the assembly of the saddle 1401 and the cord assembly
1400, 1407. The cord
assembly includes the main cord 1400, an electrical interface terminal 1406,
and the interior conductor 1407 of
the aforementioned cord that connects to the terminal 1406. The terminal 1406
rests in the closed end of the
saddle and the strain relief component 1401 and the two components are aligned
along the long axis by relief
ways in the outer contact carrier (not shown). If desired or needed, the
terminal 1406 can be mechanically
attached or bonded to the saddle and strain relief component 1401 for ease of
assembly, greater strength, or
other purposes. The capture toggle 1402 is placed during manufacture in the
saddle between the two holes in
the saddle 1401. The pre-load spring 1403 will press upon the capture toggle
1402 while the release actuation
rod 1404 rests against the opposite side of the toggle.
Figure 14B shows a side view of this assembly. The outer contact component
carrier 1409 houses and
contains each of the components and prevents injection molding plastic from
entering the interior of the carrier
during the final outer over-mold injection process. Figure 14B also helps
understand the basic operation of the
capture assembly. When the prong of the inserted plug 1405 is inserted into
the receptacle, it enters into the
plastic carrier 1409, then into the terminal 1406, and eventually passes under
the toggle 1402 until it is fully
inserted and is in the position shown. If tension is applied to the power cord
in attempt to extract it from the
mated plug, the force is transmitted from the cord to the prong 1405 and hence
to the toggle 1402 (via the strain
relief component and saddle 1401) which is pressed against the top of the
prong 1405 by the pressure of the
saddle 1401 on the bottom of the prong 1405, transmitted through the
electrical terminal 1406. The toggle is
pre-loaded against the top of the inserted prong of the plug connector 1405 by
the spring 1403. As can be
appreciated the shape of the toggle where it presses down on the prong can be
shaped to control the application
of the clamping force to the prong, for example, the toggle can have a groove
to control the force on the prong
so as not to twist it. This can also be done for the base of the saddle and
mating terminal if desired or necessary.
A suitably shaped insert between the saddle/ strain relief 1401 and a terminal
shaped to match the insert could
accomplish this function. As the force applied to the cord 1407 causes minute
movement along the major axis of
the assembly, the mating prong also begins to attempt to retract and the
toggle begins to rotate in such a
manner as to force down the top of the inserted mating prong of the plug
connector 1405, squeezing it tighter
into the terminal 1406, and hence the terminal is squeezed into the saddle
1401. The friction between the
terminal 1406, the mating prong of the plug connector 1405 and the saddle 1401
increases rapidly to a point
where the movement is ceased. The pressing down of the mating prong 1405 onto
the electrical terminal 1406
also improves the quality of the electrical connection. The prong of the plug
connector 1405 is now functionally
locked to the saddle and strain relief component 1401, and hence the cord
1407. Figure 15A illustrates from an
end-on view the relationship of all of the components involved in the locking
of the components together. The
prong of the inserted plug 1405 is located in the terminal 1406, which is
sandwiched between the prong 1405
and the saddle 1401.
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Figure 14B illustrates the mechanism to release the connection of the toggle
1402 and the prong of the
plug connector 1405. The opposite end of the release rod 1404 can extend
through the entirety of the
receptacle and protrude out the back of the connector or assembly where it is
user accessible. The release rod
1404 can also be actuated by other means such as is shown in Fig. 14D. A
telescopic section of the cord cap
1412 which includes a mechanical linkage 1408 can push the release rod 1404
against the toggle 1402 when
the telescoping section 1412 is pulled back by the user to separate the plug
assembly from the receptacle
assembly (line 1413 indicates the fully inserted depth of the front face of
the plug) . In this regard, the range of
motion of the telescoping section 1412 is controlled by elements 1410 and
1411. Pressure on the opposite end
of the rod 1404 transmits to the back of the toggle 1402 and compresses the
spring 1403 slightly. This action
rotates the bottom of the toggle 1402 up and away from the prong of the
inserted plug connector 1405 and
reduces or eliminates the contacting force between the toggle 1402 and the
mating prong 1405 allowing the
mating prong to move in the retraction direction. The receptacle can then be
separated from the plug. The
system can be designed so that the spring 1403 functions to return the
telescopic section 1412 to the locked
configuration when the user releases the section 1412.
Figure 15A illustrates the end-on view of the principal components of the
inserted prong of the plug
connector 1405 and the locking components of the receptacle in cross section.
As mentioned previously, the
toggle 1402 has been rotated into a position such that it is pressing on the
prong of the inserted plug connector
1405. The prong 1405 is in turn pressing on the terminal 1406 and in turn the
terminal 1406 is pressing on the
bottom of the saddle 1401. It should be appreciated that as axial tension on
the cord is increased the downward
force exerted by the toggle 1402 will also increase. With suitable angles
selected, and suitable dimensions of
the components, the force amplification can be about 10 to 1. In other words,
10 pounds of strain force on the
cord will result in about 100 lbs of force exerted on the prong.
It also should be appreciated that the bottom of the saddle and strain relief
component 1401 can be
manufactured with a crown shape as shown. This crown shape allows the bottom
of the saddle and strain relief
component 1401 to act like a leaf spring when pressed down by the prong. The
spring in the bottom of the
saddle allows a very controllable and predictable force to be applied to the
prong 1405 by the combination of the
toggle pressing down on the prong and the spring resisting that force as
transmitted by the prong and terminal.
The maximum clamping force of the toggle on the prong is controlled by the
resistance and travel of the spring.
This feature can be used as follows. When strain is put on the cord to pull
apart the connection, the toggle
increases its force on the prong and eventually a point will be reached where
the spring in (or under as
described in alternative embodiments discussed below) the bottom of the saddle
and strain relief component
1401 starts to flatten out. This action allows the distance from the base of
the saddle and strain relief component
1401 and the tip of the toggle 1402 to increase, allowing the toggle 1402 to
rotate. As the tension on the cord
continues to increase, a point will be reached where the distance between
saddle and strain relief component
1401 and the toggle 1402 is great enough that the toggle 1402 will rotate and
be perpendicular to the prong. At
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this point the tab on the toggle 1402 can no longer add any additional
pressure to the prong 1405, and the prong
1405 will move under the tension applied to the cord 1407 which separates the
plug and receptacle. It should
also be appreciated that the tension at which the release occurs can be
reliably predicted to occur and can be
varied by the strength and travel of the spring. The design is somewhat
tolerant of manufacturing variances of
both the inserted connector prong and the mechanical components of the locking
mechanism. It should also be
appreciated that the tension at which the mated connection releases under
strain can be reliably pre-set.
In this design, Figure 15A illustrates the end-on view of the saddle and
strain relief component 1401
with the cord crimp end away from the viewer. The crown spring depicted in the
front 1521 view has the function
of controlling the release point of the connected assembly under strain
conditions. In Fig. 15B the crown spring
is shown with a hole 1541 that is used to modify the strength and travel of
the crown spring. However, other
means such as the thickness or type or temper, etc., of the material used can
be selected to control the spring
function. Observing that the location of the hole 1541 is located directly
under the saddle section of the saddle
and strain relief component 1401, it should be appreciated that the strength
of the crown spring action is
modified. The absence of a hole will allow maximum resistance to compression
of the spring crown, and a large
hole will introduce significant reduction in spring strength. By reducing the
spring strength, the release point of
the mated connector components is subsequently reduced. Hence, the retention
capacity of the locking
receptacle can reliably set to specific release tensions. It will be
appreciated that this design further promotes
ease and lower cost of manufacture. The die that stamps the strain relief can
have an insert that can be
changed to vary the size of the hole 1541 in the leaf spring for various
values of release tension. Other means
of setting the strength and travel of the spring can be used, for example the
thickness and shape of the material
or other means. Also, other means that use a uniform or variable strength
spring of a suitable type (hairpin, leaf,
elastomer, etc) to press on the bottom of the saddle 1401 directly below the
toggle 1402 can be used. The
saddle in this case would not need to incorporate a spring, the spring would
be separate from the saddle. This
would permit the addition of a factory and/ or end user spring force
adjustment mechanism, such as a screw.
This mechanism would control the strength and travel, of the spring pressing
on the saddle and hence the
release tension of the gripping mechanism as was described earlier. The range
of adjustment could be
controlled to meet any needed requirement. It ban be appreciated that being
able to reliably set the release
tension is extremely useful - it allows a locking cord to be made that does
not require a separate release
mechanism. The release is done by the locking mechanism at the desired tension
level.
Figure 14C depicts an orthogonal view of the saddle and strain relief
component 1401. The grip ring
1408 at the end of the saddle and strain relief component 1401 is shown as an
integral part of the saddle and
strain relief component 1401. This ring can also be a separate compression
ring that is inserted over the end of
the saddle and strain relief component 1401, where the end of the saddle and
strain relief component 1402 can
be shaped appropriately to be sandwiched between said compression ring and the
end of the attached cord.
The alternate method of attaching the saddle and strain relief component 1401
to the cord is mentioned due to
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the potential difficulties in compound heat treatment along the length of the
saddle and strain relief component
1401. The saddle end of the saddle and strain relief component 1401 will
generally be heat treated, while the
crimp ring end must remain malleable. Although it is possible to manufacture
the saddle and strain relief
component 1401 with these characteristics, it may be more economical to
manufacture an alternately shaped
saddle and strain relief component 1401 and assemble it to the cord with a
separate compression ring. It can be
appreciated that the retention mechanism described will work well with other
shapes of prongs than those
illustrated, which are fiat blade type prongs. For example, the retention
mechanism will work well with round
prongs such as used in NMA 5-15 and other plugs. Only minor changes are needed
such as shaping the end
of the toggle where it contacts the round prong to have a suitable matching
shape and thickness to optimize how
the force is applied to the material of the prong. This is desirable, since
many round prongs are formed of
tubular, not solid material and therefore can be deformed or crushed by too
much force applied to too small an
area of the material they are made of. Similarly, the bottom of the saddle
and/or the electrical contact could be
shaped to spread the clamping force more evenly on to the round prong and/or
an insert between the saddle and
the terminal could be used for this purpose. Although the embodiment of
Figures 14A-15B has been illustrated
and described in relation to a conventional cord cap, it will be appreciated
that similar structure can be
incorporated into other types of receptacle devices including, for example,
the structure described in PCT
Application PCT/US2008/57140 entitled, "Automatic Transfer Switch Module,"
which is incorporated herein by
reference.
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.
Figures 4A-4C illustrate a locking device 60 for providing a locking feature
for a standard cord-cap
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. It can be appreciated that the other clamping
mechanisms described earlier could
also be employed. As described earlier some of these eliminate the need to
provide a separate release and
could optionally provide a factory and/ or user adjustable release tension
feature. 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 onto 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
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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 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. It can be
appreciated that the other clamping mechanisms described earlier could be
employed in a standard duplex
locking receptacle. As discussed earlier, some of these eliminate the need to
provide a separate release
mechanism and could optionally provide a factory and/or user adjustable
release tension feature.
= 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, 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.
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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 170 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
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 non-conductive-material. In one
embodiment, the device 170 is
constructed from a semi-rigid plastic. In this regard, the device 170 may be 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
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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.
Figure 8A illustrates 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 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. If
the recesses are not already
present, they could be designed into the receptacle.
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 toggle 196 that is
attached via a pivot to the 193 inner
portion of the prong 194. A spring 198, piston 199, and an actuating mechanism
200 function together to
enable the toggle 196 to be oriented in a lock configuration (shown in Figure
8B), and a release configuration
(shown in Figure 8C). In one embodiment, the spring 198 acts to bias the tab
198 in the release position, which
may be a substantially aligned with horizontal position inside the prong 194.
Furthermore, the actuating
mechanism 200 may be operable to rotate the toggle 196 into the unlock
position (shown in Figures 8C) where
the toggle 196 retracts into the prong 194 at an angle substantially parallel
to 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 pressure asserted by the
spring 198 and piston 199. 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. Figure 8C illustrates when a user desires to
remove the plug 190 from the
receptacle 210, they may depress the control switch 202 on the front of the
plug 190, which causes the achiating
mechanism 200 and the spring 198 to rotate the tab 196 into the release
position.
Figures 9A-9B illustrate another embodiment of a plug 220 that includes a
divergent spring tip 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).
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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 into the standard
receptacle 240, 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.
Figures 10A and 10B show a locking electrical receptacle 1000 according to a
further embodiment of
the present invention. The receptacle 1000 is generally similar in
construction to the structure of Figures 2A-2B.
In this regard, the illustrated receptacle 1000 includes an end cap formed
from an outer lock release grip 1002
that is slideably mounted on an inner contact carrier module 1004. The inner
contact carrier module carries a
number of sockets or receptacles generally identified by reference numeral
1006. The illustrated receptacle
1000 further includes cord strain relief 1010 and spring prong retainer 1008.
Figure 10B shows a perspective view of the spring prong retainer 1008. As
shown, the retainer 1008
includes a number of gripping tabs 1012 for gripping the contact carrier
module 1004. In this regard, the gripping
tabs 1012 may be embedded within the molded contact carrier module 1004 so as
to more firmly secure the
retainer 1008 to the carrier module 1004. Alternatively, the tabs 1012 may be
pressed into the carrier module
1004 or attached to the module 1004 by an adhesive or the like. In this
manner, the tabs 1012 assist in securing
the spring prong retainer 1008 to the contact carrier module 1004 and
maintaining the relative positioning
between the spring prong retainer 1008 and the contact carrier module 1004. It
will be appreciated from this
discussion below that this relative positioning is important in assuring
proper functioning of the locking
mechanism and controlling the release tension. The locking electrical
receptacle of 1000 otherwise functions as
described above in connection with Figures 2A-3B.
Figures 11A and 11B show a further embodiment of a locking electrical
receptacle 1100. Again, the
receptacle 1100 is generally similar to the structure described above in
connection with Figures 2A and 2B and
includes an outer lock release grip 1102, and inner contact carrier module
1104 including a number of
receptacles 1106, and a cord strain relief structure 1110. The illustrated
embodiment further includes a spring
prong retainer 1108 incorporating strain relief structure. It will be
appreciated that the locking mechanism of the
present invention can result in significant strain forces being applied to the
end cap in the case where large
tension forces are applied to a plug against the locking mechanism. Such
forces could result in damage to the
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end cap and potential hazards associated with exposed wires if such forces are
not accounted for in the end cap
design.
Accordingly, in the illustrated embodiment, the spring prong retainer 1108
includes strain relief structure
for transmitting such strain forces directly to the power cord. Specifically,
the illustrated spring prong retainer
1108 is lengthened and includes a cord grip structure 1114 at a rear end
thereof. The cord attachment grip
structure 1114 attaches to the power cord or is otherwise connected with a
crimping band 1112 that can be
secured to the power cord via crimping and/or welding, etc. or the like. In
this manner, strain forces associated
with operation of the spring prong retainer 1108 to grip prongs of a plug are
transmitted directly to the power
cord.
Various characteristics of the locking electrical receptacle of the present
invention can be varied to
control the release stress of the locking electrical receptacle. In this
regard, the geometry, thickness, material
qualities and detail shaping of the gripping component can be used to control
the release tension of the locking
mechanism. As an example, increasing the thickness and/or stiffness of the
material of the gripping component
increases the release tension of the locking mechanism.
The geometry of these spring prong retainers may also be varied to provide
improved safety and
performance. .Figure 12 shows on example in this regard. The illustrated
spring prong retainer 1200, which may
be incorporated into, for example, the embodiments of Figures 2A-2B, 10A-10B,
or 11A-11B, includes a
narrowed neck portion on 1202 between the flex point 1204 of the spring prong
retainer and the prong
engagement opening. This neck portion may provide a number of desirable
functions. For example, the neck
portion 1202 maybe positioned to provide greater clearance between the spring
prong retainer 1200 and the
other prongs of plug. In addition, the narrow portion 1202 may be designed to
provide a defined breakpoint in
the case of structural failure. That is, in the event breakage occurs due to
stress or material fatigue, the neck
portion 1202 provides a safe failure point that will not result in electrical
hazards or failure of the electrical
connection.
It can be appreciated that all of the retention mechanisms described herein
that can have their release
tension changed by varying their design parameters, can have a release tension
that is coordinated with the
receptacle design or a standard or specification so as to ensure that the cord
cap or receptacle will not break
resulting in a potentially hazardous exposure of wires. Thus, for example, it
may be desired to provide a release
stress of forty pounds based on an analysis of an end cap or receptacle
structure, a regulatory requirement, or a
design specification. The locking mechanism may be implemented by a way of a
spring prong retainer as
shown, for example, in Figures 2A-2B, 10A-10B and 11A-11B. Then, the material
and thickness of the spring
prong retainer as well as the specific geometry of the spring prong retainer
may be selected so as to provide a
release stress of 40 lbs. The locking mechanism with a release stress of 40
lbs can also be implemented in the
toggle and saddle mechanism as shown, for example in Figures 14A-14D and 15A-
15B. The values of these
various design parameters may be determined theoretically or empirically to
provide the desired release point.
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Figures 16A-16B illustrate an embodiment of a retention mechanism for securing
a mated electrical
connection that may be included in a secure connection of the present
invention. In Figures 16A-16B, the top
portion represents a top view of a mated plug and receptacle 100 and a
retention mechanism 1020, while the
bottom portion represents a perspective view. The electrical prongs 1030 may
be two or more in number (e.g.,
an IEC 320 plug, a NEMA 5-15, or the like) and may be various sizes and
shapes. Further, the plug and
receptacle 1000 may be the plug and receptacle of a standard outlet (e.g., an
IEC 320 cord cap, or the like).
The plug also includes the retention mechanism 1020. The design of the secure
retention mechanism 1020 is
such that a simple slide in and then secure the connection technique is
utilized. Referring next to Figure 17A,
the plug and receptacle are shown mated but prior to the connection being
secured. This embodiment is one that
the user must manually elect to secure, as described earlier.
Figures 17A-17B illustrates the plug 2010 when inserted into the receptacle
2020. As shown, the plug
and receptacle are in a mated, but not yet secured position. The manual
actuation nut 2030 is twisted by the
user to secure and release the connection. The nut can have an optional
ratcheting mechanism as described
earlier, this is not shown. The outer shell 2040 is pressed into the elastomer
2050 by the action of the nut 2030,
when the nut is tightened. The outer shell will compress the elastomer when
tightened and will be pushed back
by the expansion of the elastomer when the nut is loosened. Optionally, the
shell can be positively attached to
the nut using an appropriate mechanism (such as a mushroom ended pin going
through a semi-circular slot in
the nut) to insure that it is positively retracted when the nut is loosened.
This is an optional construction that is
not shown. The blow-up portions of the diagram, 2100 and 2200 show two
different possible instantiations of this
part of the mechanism. Detail 2030 shows the shape of the area of the
mechanism where the elastomer is
compressed as substantially rectangular. Detail 2040 shows the shape of the
area of the mechanism where the
elastomer is compressed in a shape that utilizes inclined ramps to compress
the elastomer. As will be
appreciated, the materials and detailed geometry of both 2100 and 2200 can be
varied to optimize their function
as described earlier.
Figures 18A-18B illustrates the plug 3010 when inserted into the receptacle
3020. As shown, the plug
and receptacle are in a mated and secured position. The manual actuation nut
3030 has been twisted by the
user to secure the connection. The outer shell 304 is being pressed into the
elastomer 3050 by the action of the
nut 3030, which is tightened down. The outer shell is compressing the
elastomer, which in turn is pressed tightly
against the wall 3060 of the abutting receptacle 3020. This is shown in more
detail in the blow-up portions of the
diagram, 3100 and 3200. The outer shell 3040 will be pushed back by the
expansion of the elastomer when the
nut 3030 is loosened. Optionally, the outer shell 3040 can be positively
attached to the nut using an appropriate
mechanism (such as a mushroom ended pin going through a semi-circular slot in
the nut) to insure that it is
positively retracted when the nut is loosened. This is an optional
construction that is not shown. Detail 3100
shows the shape of the area of the mechanism where the elastomer is compressed
as substantially rectangular.
Detail 3200 shows the shape of the area of the mechanism where the elastomer
is compressed in a form that
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utilizes inclined ramps to compress the elastomer. As will be appreciated, the
materials and detailed geometry
of both 3100 and 3200 can be varied to optimize their function as described
earlier.
Figures 19C illustrates a blowup of another possible instantiation of the
invention. The tabs 3300
located on the outer shell 3310 are driven axially forward by the action of
the nut 3340, when it is tightened
down. The tabs 3300 push forward over ramps 3320 in the part of the assembly
that is inserted into the matching
receptacle. The example in Fig. 19C shown is a male C13, but the same concepts
and mechanisms work with a
female C13 as shown in Fig. 19D. The only substantial difference in
construction between the male C13 shown
in Fig. 19C and the female C13 shown in Fig. 19D is how the electrical
contacts are located, in the female
version a contact carrier 3480 (which is usually a safety agency approved
part) is molded into the cordcap. The
outer shell 3470 can be overmolded onto the contact carrier or made as a
separate part that snaps over the
contact carrier, which is the construction shown in Fig. 3D. Other
construction methods are possible. The
geometry, material, location, number and mechanical action of the tabs 3300,
3400 and ramps 3320, 3420 can
be varied to insure that the area of maximum pressure exerted by the ramps
contacting the mated receptacle is
located as desired. This can be important to maximize the retention force and
insure that the receptacle can
withstand the force applied by the tabs 3300, 3400 without damage. The tabs
3300, 3400 can be one or more in
number, and can be located to maximize the retention force of the mechanism.
They may or may not be located
to oppose each other, which can be used to insure that the force applied to
the receptacle maximizes the
retention force. As shown, the tabs 3300, 3400 would tend to apply force to
the receptacle such that the walls of
the receptacle are stressed in tension, which can be desirable, depending on
the material of the receptacle. The
surface of the tabs 3350 ,3450 that contacts the wall of the mated receptacle
can be made of one or more
materials with suitable mechanical and frictional characteristics. An example
of a possible instantiation would be
to make the outer shell 3310, 3410 of a harder, mechanically strong material
and then coat or the tab surfaces
3350, 3450 with a high friction coefficient elastomer. This could be
economically done via a coinjection
("sandwich") molding process, for example. As can appreciated, in reaction to
a withdrawal force 3385,3485
applied to the cord 3380, 3480, the retention mechanism as shown in Fig. 18C,
18D will transmit the force via
the cord 3380, 3480 to the end of the cordcap 3390, 3490. This will compress
elastomer injection molded
materials that are commonly used to make electrical cords, resulting in the
end of the cordcap being moved
slightly closer to the outer shell 3310, 3410 which moves the tabs 3300, 3400
farther up the ramps 3340, 3440
which presses the contact area of the tabs 3350, 3450 into closer and closer
contact with the walls of the
receptacle, causing the frictional interlock between the plug and the
receptacle to increase. Thus, the very force
3385, 3485 that tends to withdraw the plug from the receptacle acts to engage
the retention mechanism to
frictionally interlock with the walls of the receptacle, thereby preventing
the withdrawal of the plug, and
maintaining the electrical connection of the mated assembly. The geometry,
material and mechanical action of
the tabs 3300, 3400 and ramps 3320, 3420 can be also be varied to provide a
programmable release '
mechanism by limiting the force applied to the walls of the mated receptacle
and thus the frictional interlock
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between the contact surfaces of the tabs 3350, 3450 and the walls of the mated
receptacle. Limiting the frictional
interlock limits the maximum force the secured connection can resist. Once
that level of force is applied, the plug
and receptacle will separate. As discussed earlier, the level of the maximum
force can therefore be specified to
prevent damage to the plug and receptacle and/or meet an applicable standard
and as also discussed earlier a
range of retention force values that can be adjusted by the user via the
action of the nut 3340, 3440.
Figures 19-22 illustrate the operation of another embodiment of a mechanism
for securing a mated
electrical connection that may be included in a secure connection of the
present invention. This embodiment is
one that automatically secures itself in response to a force 6070 that would
tend to pull the connection apart.
Figures 20-22 represents top views of the retention mechanism in the states
of: 1) fully inserted 5000, 2) fully
inserted under tension 6000, 3) being released 7000. Figure 19 illustrates the
plug and receptacle and the
elements of retention mechanism. Figure 20 illustrates the connection after
the plug has been inserted into the
receptacle but no force has been applied that would tend to pull the
connection apart. Figure 21 illustrates the
operation of the retention mechanism 6000 in reaction to a force on the plug
601 that tends to withdrawal the
plug 6010 from the receptacle 6020. In reaction to a withdrawal of the plug
6010, the retention mechanism as
shown in detail blowup 6100 via the action of the inclined ramp 6040 forces
the elastomer 6050 into closer and
closer contact with the walls of the receptacle 6060, causing the frictional
interlock between the plug 6010 and
the receptacle 6020 to increase. Thus, the very force 6070 that tends to
withdraw the plug 6010 from the
receptacle 6020 acts to engage the retention mechanism 6000 to frictionally
interlock with the walls of the
receptacle 6060, thereby preventing the withdrawal of the plug 6010, and
maintaining the electrical connection of
the mated assembly. The retention mechanism 6000 may be constructed of any
suitable material as described
earlier. Figure 22 illustrates the operation of the retention mechanism during
release of the secure connection.
When the user desires to release the connection, they can grasp and pull the
outer shell 7030 which will retract,
pulling 7070 the elastomer 7040 back down the ramp 7050, via the extension of
the outer shell 7060,
uncompressing the elastomer 7040 thus releasing the connection.
Figures 23-24 illustrate the operation of another embodiment of a mechanism
for securing a mated
electrical connection that may be included in a secure connection of the
present invention. This embodiment is
one that automatically secures itself in response to a force that would tend
to pull the connection apart. Figure 23
illustrates a side top of the plug 8000 that incorporates the secure
mechanism, and side view 8010 and
perspective views 8020 of a typical standard receptacle. The receptacle has
fingers 8030 that are used to secure
the receptacle 8020 when it is snapped into a panel. These fingers 8030 are
typically provided in individually
molded snap-in receptacles 8020 and typically provided in molded models of
receptacles that provide 2, 3 or
more receptacles in one molded unit for snap-in insertion into a plugstrip.
The fingers 8030 splay when the
receptacle 8020 is inserted, leaving an opening in the body of the receptacle
8020. Where the fingers are not
provided, the manufacturer could alter the molding to insure they or a
similarly shaped and located slot or hole
are provided in every model of individual or multiple receptacle, at low cost
with little or no impact on regulatory
29
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body approvals, making it easy and inexpensive to offer. The plug 8000 has
tabs 8040 (that optionally can be
shaped as hooks) that will expand and insert themselves into the openings in
the body of the receptacle 8020
when the plug 8000 is inserted into the receptacle 8020. The ends of the tabs
8040 can be located and shaped
so that they can insert themselves into and transfer forces that would tend to
pull the connection apart to the
walls of the receptacle, but not pass through the opening in the wall of the
receptacle 8020. This insures that the
tabs 8020 cannot become wedged by the walls of the receptacle in response to a
force that would tend to pull
the connection apart and therefore separate the plug 8000 and receptacle 8020.
This shaping of the tabs 8020
insures that the secure connection will function properly and always release
when desired. To release the
connection the user grasps the outer shell 805, and pulls it back to pull the
plug 8000 out of the receptacle 8020.
Figures 24a-24e represents top views of the retention mechanism with an
electrical contact prong in
the states of: : 1) partially inserted Fig. 24a, 2) being inserted but not yet
secured Fig. 24b, 3) fully inserted and
secured 9020 Fig. 24c, 4) fully inserted while being released 9030 Fig. 24d,
5) being removed, thus breaking the
connection 9040 Fig. 24e. As described above, and demonstrated in Figures 24a-
24e the plug 8000 has tabs
8040 (that optionally can be shaped as hooks) that will expand and insert
themselves into the openings in the
body of the receptacle 8020 when the plug is inserted into the receptacle
8020. To release the connection the
user grasps the outer shell 8050, and pulls 8060 it back to pull the plug 8000
out of the receptacle 8020 as
demonstrated in Figure 24d and Figure 24e. The outer shell 8050 is equipped
with suitably shaped substantially
rectangular openings for the tabs 8040 to extend through and when the outer
shell 8050 is pulled 8060 back by
the user, the edge 8070 of the rectangular opening that is closest to the
front of the male plug will depress the
tabs 8040, freeing the plug 8000 to disconnect from the receptacle 8020. The
retention mechanism may be
constructed of any suitable material as described earlier. It should be noted
that this embodiment of the
mechanism could easily be combined with the earlier versions described that
use a user activated manual
retention mechanism. This instantiation would use the actuation nut described
earlier to control the position and
movement of the outer shell. The release position of the actuation nut would
position the outer shell to depress
the tabs, preventing their engagement with the receptacle, but not preventing
the plug from being inserted into or
removed from the receptacle. The secure position of the actuation nut would
allow the tabs to engage with the
receptacle, securing the connection. This version might be useful in some
circumstances.
The foregoing description of the present invention has been presented for
purposes of illustration and
description. Furthermore, the description is not intended to 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.
