Electrical connectors – With coupling separator – Nonconducting pusher
Reexamination Certificate
2002-10-08
2004-04-06
Luebke, Renee (Department: 2833)
Electrical connectors
With coupling separator
Nonconducting pusher
C439S159000
Reexamination Certificate
active
06716044
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is in the field of electrical connectors. Specifically, the present invention is related to assisted-release electrical connectors.
BACKGROUND
Many electrical devices rely upon electrical cables such as power cords to connect the device to a power source, such as a wall-mounted electrical outlet. Additional electrical cables, such as extension cords, are often required to extend the range of the electrical device from an outlet due to limited outlet availability or because the power cord of the electrical device is too short to reach an available outlet.
An electrical cable typically comprises insulated conductors, such as wire, of a desired length. Typically, one end of the electrical cable terminates in a male connector, while the opposite end terminates in the electrical device or a female connector. Connectors are designed to terminate conductors and cables between electrical circuits within a system, between systems, and between systems and external power sources and signal lines.
A male electrical connector is commonly referred to as a “plug.” Female electrical connectors are also commonly called “receptacles,” “sockets,” “jacks,” or “outlets.” Examples of plugs in the art include, but are not limited to a flat blade plug as shown in
FIG. 1A
(along with an electrical outlet), and a flat blade plug with a grounding terminal as shown in
FIG. 1B. A
male electrical connector, i.e., plug, typically mates with a female connector of the same size and number of conductors.
As shown in
FIG. 2
, a male electrical connector
200
may comprise a body
202
made from an electrically insulative material. The body
202
has a mating surface
204
from which conductive projections
206
extend. The mating surface
204
can be pressed substantially against a mating surface
304
of a female connector (shown in
FIG. 3
) so as to place the two connectors in electrical communication. The body
202
of the male connector typically houses the electrical connection (not shown) between the conductors in an electrical cable
208
and the conductive projections
206
.
As shown in
FIG. 3
, a female electrical connector
300
may comprise a body
302
made from an electrically insulative material. The body
302
has a mating surface
304
in which cavities
306
are formed. The cavities
306
contain conductive receivers
308
adapted to accept the insertion of conductive projections
206
(shown in FIG.
2
). The body
302
of the female electrical connector
300
typically encapsulates the connection (not shown) between the conductors within an electrical cable
310
and the conductive receivers
308
.
Typically, a plug is held in a receptacle after insertion due to a friction fit between the conductive projections of the male connector and the corresponding conductive receivers of the female connector. The friction fit is due to the insertion force required to overcome the interaction of the conductive projections of the male connector with the conductive receivers of the female connector when coupling the connectors, and is a desirable characteristic in order to achieve and maintain a good electrical connection.
A male connector coupled with a female connector is referred to as a “connector assembly.” A connector assembly can typically be uncoupled by applying sufficient force to pull the male and female connectors apart. However, the amount of force required to uncouple the connectors can often be excessive for a number of reasons, creating difficulty in separating the connectors. Connector assemblies can also be difficult to uncouple if the connector assembly is located in a partially obstructed or difficult-to-reach area such as behind furniture. Another factor that can make connector assemblies more difficult to uncouple is the addition of more conductors, such as a grounding terminal, which increases the friction fit between the male and female connectors and changes the overall dynamics of the uncoupling process. A partially separated connector assembly is an undesired condition, as it exposes the conductive projections of the male connector, creating a shock hazard. In addition, another conductive material could contact the exposed projections and cause a short circuit or fire.
Prior attempts have been made to solve this problem. For example, Schlums U.S. Pat. No. 2,051,425 teaches an electric plug having a cammed means for detaching the plug from a receptacle. The detaching means comprises a cam having an outer arm portion and an actuator portion. To uncouple the plug from the socket, the outer arm portion of the cam is depressed, causing the actuator portion to apply an oblique force against the mating surface of the receptacle, urging the plug from the receptacle due to the curvature of the actuator portion. The amount of mechanical advantage employed by the cam decreases as the outer arm portion of the cam is moved toward the plug's housing. The stated purpose for this configuration is to match the mechanical advantage of the cam to the detaching force required, the rationale being that a greater amount of force is required to initiate separation of the plug and receptacle when the surface area contact between the male and female connectors is the greatest. The amount of force required decreases as the plug and receptacle separate.
The movement of a representative cam as disclosed by Schlums is depicted in FIG.
4
. As an outer arm portion
402
of a cam
400
is pressed downward, the cam
400
rotates about a fulcrum
404
. As the cam
400
rotates, an actuator portion
406
extends laterally to apply force against a mating surface
408
of a receptacle. As can be seen, the amount of lateral movement exhibited by the actuator portion
406
as the cam is rotated from position a1 to positions a2 and a3 is limited due to the curvature of the actuator portion
406
, which is necessary to effect a varying mechanical advantage. Thus, to achieve the amount of cam actuator movement necessary to ensure separation of the plug and receptacle the cam as taught by Schlums would require a larger connector housing than is practical for modern power connectors.
An alternate embodiment of the electric plug as taught by Schlums features a single cam of the type generally depicted in
FIG. 5
situated between the conducting projections of a male connector. The actuator portion
406
′ of this cam
400
′ is shaped with less curvature than the cam shown in
FIG. 4
such that the actuator portion
406
′ has little variation in mechanical advantage. In this configuration, a smaller contacting portion
510
of the actuator portion
406
′ comes into contact with the mating surface
408
′ of a receptacle. Although the cam
400
′ exhibits greater lateral movement than the cam shown in
FIG. 4
, the amount of lateral movement is still less than necessary to ensure complete disengagement of the connector assembly.
The cams shown in
FIGS. 4 and 5
both suffer from limited lateral movement of the actuator portion
406
,
406
′, which can result in incomplete disengagement of the plug and receptacle. In addition, the amount of lateral movement provided by the actuator portion
406
,
406
′ is not proportional to the movement of the outer arm
402
,
402
′. As a result, the plug begins separating from the receptacle at a slow rate as the cam
400
,
400
′ moves from position a1 to position a2, and accelerates as the connector disengagement cycle continues to position a3. The partially exposed conductive projections of the plug create a risk of arcing between conductors, short circuits, and electrical shock. Thus, it is desirable not only to ensure complete disengagement of the plug and receptacle, but also to minimize the time required to disengage the plug from the receptacle.
A further limitation of the device disclosed by Schlums is that a suitably sized actuator portion would likely interfere with a third conductor, such as the grounding terminal commonly found on modern power cords. R
Eley, Esq. James R.
Forhan, Esq. Michael A.
Luebke Renee
McCamey Ann
Thompson Hine LLP
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