EP2754210B1

EP2754210B1 - Secure electrical receptacle

Info

Publication number: EP2754210B1
Application number: EP12829816.3A
Authority: EP
Inventors: William Pachoud; Steve Chapel; Martin S. Reaves
Original assignee: Zonit Structured Solutions LLC
Current assignee: Zonit Structured Solutions LLC
Priority date: 2011-09-08
Filing date: 2012-09-10
Publication date: 2018-10-24
Anticipated expiration: 2032-09-10
Also published as: WO2013036966A3; EP2754210A4; AU2012305707B2; WO2013036966A2; CN103918138A; CA2854448C; AU2012305707A1; CN103918138B; EP2754210A2; CA2854448A1

Description

BACKGROUND

A wide variety of electrical connectors are known to provide electrical contact between power supplies and electrical devices. Connectors typically include prong type terminals, generally referred to as plugs, and female connectors designed for receiving the prong type terminals, generally referred to as receptacles, often described as electrical outlets, or simply outlets. The most common types of outlets include a pair of terminal contacts that receive the prongs of a plug that are coupled to "hot" and "neutral" conductors. Further, outlets may 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 limited to, manufacturing processes, foreign materials acting as lubricants, and wear and distortion of the assemblies. This characteristic results in a non-secure means of interconnecting 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. The above mentioned technical problems are therefore solved by the assembly of independent claim 1 and the method of independent claim 6, said assembly having a locking electrical receptacle and an electrical plug to be used in conjunction with.
US 2009/325427 relates to an electrical plug connector having pretensioned contact plates, and it discloses the preamble of claim 1. Namely this document discloses (references to this document between brackets) a locking electrical receptacle (fig. 1) for use in conjunction with an electrical plug (implicit feature) including at least one elongate extending plug structure (4) comprising:

receptacle structure (2, 2a) defining a receptacle (3) for receiving said elongate extending plug structure (4);
elongate gripping elements (8) movably mounted on said receptacle structure (2a), said gripping elements (8) being disposed at least on opposite sides of said receptacle; and
actuation structure (6), operatively associated with said elongate gripping elements (8), for forcing said elongate gripping elements (8) into secure frictional engagement with opposing surfaces (4a) of said elongate extending plug structure (4) responsive to a withdrawal force exerted on electrical plug and urging said elongate extending plug structure (4) to withdraw from said receptacle (see figs. 2-4).

US 7473123 relates to an electrical disconnect with radially spaced terminals.
WO 2011/001821 relates to a female terminal.

SUMMARY

The present disclosure 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 disclosure 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 disclosure further provides a variety of mechanisms whereby the user can manually elect to actuate the retention mechanism thereby securing the mated pair. The mechanisms are of simple construction and highly reliable in operation. Moreover, the disclosure 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 example of the present disclosure, 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.
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 example of the present disclosure, 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 example of the present disclosure, 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 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 example of the present disclosure, 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 example of the present disclosure, 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 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 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 example of the present disclosure, 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.
In accordance with a further example of the present disclosure, 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 example of the present disclosure, 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).
In accordance with a still further example of the present disclosure, 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. 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., Aspects of the invention are defined in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A-1C illustrate the operation of an example of a clamping mechanism in accordance with the present invention.
Figures 1D-1F and 1H-1J illustrate the operation of another example of a clamping mechanism.
Figure 1G illustrate the operation of another example of a clamping mechanism.
Figures 2A-2B illustrate an example of a locking electrical receptacle using the clamping mechanism described in Figures 1A-1C.
Figure 2C illustrates an example of a locking electrical receptacle using the clamping mechanism described in Figures 1D-1F, 1H-1J or 1G.
Figure 3A-3B illustrate ah application for the locking electrical receptacle shown in Figures 2A-2B.

DETAILED DESCRIPTION

While the disclosure is susceptible to various modifications and alternative forms, specific examples 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 disclosure to the particular form disclosed, but rather, the present invention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the claims.
Figures 1A-1C illustrate the operation 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 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 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 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 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 example, 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 90° angle to the plane of stamping of the material) to affect the pivot point and flexing properties of the spring as may be desired,
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 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 example 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 example 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 (undemeath 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 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 40 is 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.
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.
The foregoing description of the present disclosure has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the disclosure to the form disclosed herein.

Claims

An assembly having a locking electrical receptacle (10, 20, 820) and an electrical plug (50) including at least one elongate extending plug structure (530, 600, 706), said receptacle for use in conjunction with said plug, this locking electrical receptacle comprising:
receptacle structure (10, 20, 820) defining a receptacle for receiving said elongate extending plug structure;

elongate gripping elements (606, 704, 705, 902) movably mounted on said receptacle structure, said gripping elements being disposed at least on opposite sides of said receptacle; and

actuation structure (601-603, 701-703, 903), operatively associated with said elongate gripping elements, for forcing said elongate gripping elements into secure frictional engagement with opposing surfaces of said elongate extending plug structure responsive to a withdrawal force exerted on electrical plug and urging said elongate extending plug structure to withdraw from said receptacle;
characterised in that
said actuation structure (601-603, 701-703, 903) comprises a connecting structure (602-603, 701-702), said connecting structure comprising at least two cross-link spring members (603, 901) for interconnecting said gripping elements such that relative lateral movement of one of said gripping elements with respect to the other causes said gripping elements to be drawn towards one another so as to more firmly grip said elongate extending plug structure;
wherein said connecting structure (602-603, 701-702) is pivotally interconnected to said gripping elements such that said gripping elements are constrained to maintain a substantially parallel relationship in connection with said relative lateral movement,
wherein the angle between any of each of the axes defining the elongate gripping elements and any of each of the axes defining the cross-link spring members, is different from 90 degrees, wherein the receptacle (10, 20, 820) further comprises a release mechanism (607, 904-905) for reducing said frictional engagement of said gripping elements and said elongate extending plug structure when desired, and
wherein said release mechanism (607, 904-905) comprises a release rod (607) or a release shaft (904) for allowing a user to initiate relative longitudinal movement as between said gripping elements.
An assembly according to Claim 1, wherein said cross-link spring members (603, 901) can lengthen under tension.
An assembly according to Claim 2, wherein said cross-link spring members (603, 901) have an arcurate shape that resiliently straightens under tension.
An assembly according to Claim 1, wherein said elongate extending plug structure (530, 600,706) comprises a prong (600) having first and second side surfaces for making electrically conductive contact with contact surfaces (609) within said receptacle, and top and bottom surfaces extending between said first and second side surfaces, and said elongate gripping elements (606, 704, 705, 902) are positioned so as to engage at least said top and bottom surfaces.
An assembly according to Claim 1, wherein said release structure comprises a receptacle housing shell mounted for telescopic movement with respect to a housing core, wherein one of said gripping elements (606, 704, 705, 902) is mounted in fixed relation to said core and another of said gripping elements moves in response to movement of said housing shell.
A method for use in securing an electrical connection involving an assembly according to any preceding claim, said assembly having a locking electrical receptacle (10, 20, 820) and, an electrical plug (50) including at least one elongate extending plug structure (54, 600,706), comprising the steps of:
providing the electrical receptacle according to the assembly of any preceding claim, said gripping elements (606, 704, 705, 902) having a receiving condition, wherein said gripping elements are ready to receive said elongate extending plug structure, and a gripping condition, wherein at least one of said gripping elements is disposed in frictional engagement with said elongate extending plug structure; and

inserting said elongate extending plug structure of said electrical plug into said receptacle such that said gripping elements are in said gripping condition.
A method as set forth in claim 6, wherein said step of inserting comprises spreading said gripping elements (606, 704, 705, 902) apart.
A method as set forth in claim 6, further comprising moving said gripping elements (606, 704, 705, 902) from said gripping condition to a release condition prior to withdrawing said elongate extending plug structure from said receptacle.
A method as set forth in claim 8, wherein said step of moving comprises causing relative longitudinal movement as between said gripping elements.