GB2324419A - Power and signal safety disconnector - Google Patents

Abstract

Couplers used to connect power and signals to equipment via transmission mediums, e.g. a connector for a flexible electric cable, are modified so as to perform a physical disconnection when the mechanical tension across the coupler is raised to a triggering level. This action is performed to prevent a physical hazard arising; when a strong, physical connection is made, a physical hazard to equipment or to people may be introduced if inadvertent contact is made with the transmission medium. Many arrangements for achieving the tension-triggered disconnections are possible. One arrangement makes use of a spring 18 that stores energy as it is compressed during the making of the connection. A catch 14 and stop 17 hold the connector together until mechanical tension across the device is sufficient to trigger the release of the catch 14, the spring 18 then releases the stored energy and forces apart the connection.

Description

POWER AND SIGNAL SAFETY DISCONNECTOR This invention relates to devices used for the physical disconnection of mediums used supplying equipment with power or signals. Such transmission mediums are required to transmit the power or signals from outlets, which are physically separated from the equipment, to the equipment. When the physical connection is made, by, for example, flexible cable for the supply of electricity or flexible pipes for the supply of air or hydraulics, those cables or pipes may present a physical hazard to the equipment or to people when inadvertent contact with those cables or pipes is made. This invention relates to the breaking of the physical connection under conditions whereby such a hazard may result in causing harm either to equipment or people.

Couplers for connecting transmission mediums both at power and signal outlets and at the equipment are widely used in various types. Couplers are also used, where required, to extend the length of transmission mediums. Connectors usually consist of two parts; commonly the plug and socket (or 'connector'). When these two parts are secured together a connection is made such that the power or signal being transmitted is largely unaffected by that connection. As such, the connection should function as a seamless extension of the transmission medium. To ensure the integrity of the connection, couplers are commonly fitted with a means of securing fast the plug and socket so that any reasonable mechanical force applied to the transmission medium will not result in a full or partial disconnection at the coupler. Some couplers use the physical strength of the connection at the plug and socket alone to provide this retaining force.

The making of the secure connection to resist disconnection does, however, give rise to physical hazards. Some of these hazards have now become well known such as: the trailing power lead of an electric iron that can result in the iron being pulled from a height (a major issue in child safety); office equipment being pulled from desks or tables due the entanglement of a passing person's leg with a trailing power lead connected to the equipment; people being hurt from trips arising from the entanglement of their feet with a trailing power lead; and damage to electric cables arising from forces above the designed limit being applied to the cable and sometimes resulting in electrocution. Other hazards are conceivable such as personal injury arising from an unanticipated force being applied to the power lead of a hand-held power tool (e.g. drill, grinder, or saw), or the pulling over of an unstable item of equipment like a drip stand used in hospitals arising from the entanglement of a person's leg with a trailing power lead supplying the equipment with power.

According to the present invention there is provided an adaptation on the standard couplers widely available such that the coupler will physically disconnect upon the application of a level of mechanical tension that is not sufficiently high to give rise to a physical hazard but not too low so as to disconnect for no reason of safety. The degree of adaptation can vary in extent from the direct usage of available couplers mounted within a body containing the necessary additional features to the complete custom design of the whole device including the means of coupling. The adaptation provides a mechanism that detects the presence of the triggering level of tension which in turn activates a mechanism that gives rise to the physical disconnection. Depending upon the type of power or signal being transmitted, it may also be necessary to shut off the energy transmission path at the plug and socket such as would be the case with air or hydraulics, but not with electricity (although couplers used for disconnecting electricity need to be designed for such a purpose). The triggering level of tension may be set at a predetermined level by design of the components or it may be made adjustable across a range, depending upon the intended application. The invention is herein as a tension-triggered power disconnector (TPD) which is descriptive of its function, especially if it is accepted that signals too are forms of power.

Various types of the TPD are required to accommodate the range of applications. For general application, an in-line version will be required; this type of TPD will be inserted in the transmission medium at an appropriate point such as a short distance after the connection of the power or signal outlet. For this application a TPD may be installed in between a standard plug and socket on a short length of transmission medium.

Alternatively, or in-addition, it may be inserted in the transmission medium at a point a short distance from the connection at the equipment. It may also be appropriate in some situations to insert the in-line TPD at a considerable way into the length of the transmission medium, where required in some situations in order to avoid trip hazards for example.

For equipment where the nature of the equipment gives rise to the hazard, such as handheld grinder, part of the connector could be in-built into the equipment so as to force the use of the TPD in the interests of safety. Likewise, where the location or designated use of certain power or signal outlets demands the use of a TPD, then part of the TPD should be in-built into the outlet so as to force the use of the TPD in the interests of safety.

The form of construction of the TPD will vary depending upon the environment that it is intended to be used in. Industrial applications will have to conform to the appropriate standards, domestic applications will be subject to less stringent standards. Indoor and outdoor applications will also require different forms of construction. Special considerations will need to be applied for the use of electrical connectors that are required to be used in potentially explosive atmospheres. Various sizes of TPD will be required according to the magnitude of power or signals that are required to pass through the TPD.

The force used to make the disconnection may be derived from several sources. The simplest means is to use the force giving rise to the tension across the TPD, this however can only be considered if the force required to make the disconnection is less than the desired triggering tension. The use of stored energy introduced during the making of the connection may be used. An example of such would be the compression of a sufficiently strong spring which is latched in compression when the connection is made; upon detection of the presence of the triggering level of tension, the latch is released and the unleashed force of the spring breaks the connection. Where sufficiently high power is being transmitted through the transmission medium, this power may also provide the disconnecting force by introducing a suitable means of using such power in the TPD.

On power or signal supplies to certain items of equipment, the breaking of the transmission medium may not be a tolerable option due to the additional hazards that this may bring. In such situations the use of the TPD will not be appropriate and should be avoided. However, on equipment that has the facility to switch to a local back-up mode upon the disconnection of power or signals, a TPD may still be used although the additional capability of providing an auxiliary signal to indicate that the disconnection has been made may be required.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in cross-section the three assembled parts of an in-line electrical TPD using a spring as the means of applying the force to achieve physical disconnection.

Figure 2 shows in cross-section and end view the tension-detecting part of the TPD.

Figure 3 shows in cross-section and end view the main body of the TPD embodying the socket.

Figure 4 shows in cross-section and end view the plug arrangement.

Referring to the drawing, the embodiment of an in-line electrical TPD using a spring disconnection mechanism comprises three parts: a tension-detecting part as illustrated in Figure 2, the main body as illustrated in Figure 3 which houses the socket and provides the means of disconnection, and the plug as illustrated in Figure 4 which is ejected by the main body when the assembled and connected unit, as illustrated in Figure 1, detects that the triggering level of tension is being applied.

When the assembled and connected unit as illustrated in Figure 1 is in use, tension in the transmission medium 1 (in this case the electric cable) will apply a force to the tensiondetecting part in the direction of the arrow 2. The cable clamps 3 and 18 are the means by which the force is applied to the tension-detecting part from the cable and therefore the points of electrical connections 4 and 19 are not brought into tension. The force on the tension-detecting part is transferred to the lever 5 of the main body by the connection made at the point 6 on the strap 7 of the tensionaetecting part. The only other secure connection made between the tension-detecting part and the main body is the electrical connection made between the terminals 8 and terminals 9 but these should never be brought into tension so sufficiently slack wiring is required between these terminals.

The movement of the lever 5 in the direction of arrow 2 applies a force to lever 11 via lever 12 with assistance from the constraining action of the solid section 13. This results in the catch 14 at the end of the lever 15 being forced in the direction of the arrow 16. When the tension force applied to the tension-detecting part is equal to the designed triggering tension, the force applied to the catch 14 in the direction of the arrow 16 will be sufficient to raise the catch 14 above the stop 17 of the plug part. This will release the energy of the compressed spring 18 which results in the plug part being ejected from the main body and thus forcing the disconnection of the electrical plug 24 and socket 20.

Following the actuation of a disconnection, the plug part is pushed into the main body to re-make the electrical connection between the plug 24 and the socket 20. This action requires that the spring 18 is forced into compression thus storing the energy required for any subsequent disconnection requirement. The latching of the plug part to the main body is made by the coming together of the catch 14 and the stop 17, this connection is assisted by a spring at the fulcrum 21 that applies a slight force in the opposite direction to the arrow 16. The alignment of the catch 14 with the stop 17 and the alignment of the plug 24 with the socket 20 is achieved by the three keys 22 and three slots 23 in the main body and plug part respectively.

Variations on this specific embodiment are easily envisaged such as: the replacement of the lever mechanisms with other force-transferring mediums such as cord; the release of the disconnecting energy in the spring could be achieved by displacement of the stop 17 at the detection of the triggering tension rather than the displacement of the catch 14; spring pretensioning of the release mechanism could be used either to increase or decrease the level of triggering tension required and this could also be made adjustable such that the user could adjust the trigger tension across a range.

Claims (9)

1. A tension-triggered power disconnector (TPD) that is an adaptation on standard couplers, used for the connection of power and signal transmitting mediums, such that the coupler will physically disconnect upon the application of a level of mechanical tension in the transmission medium that is not sufficiently high to give rise to a physical hazard but not too low so as to disconnect for no reason of safety.

2. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments are suitable for use on all transmission mediums requiring physical connection to transmit power or signals of all forms, including, where applicable, a means of stopping the flow of energy through the transmission medium upon the breaking of the physical connection.

3. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments are suitable for connecting in-line in transmission mediums or having part of the device integrated in the equipment being supplied with the power or signal or integrated in the outlet supplying the power or signal.

4. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments have triggering levels of tension either set at a predetermined level or have the facility for the user to adjust the triggering level of tension across a range of possible settings.

5. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments are designed to be suitable for the foreseen specific environments in which the function of the TPD may be required.

6. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments use any suitable means of energy to effect the disconnection including: the force giving rise to the tension; the use of stored energy introduced during the making of the connection, such as that obtained by the compression of a spring; and the power being transmitted through the transmission medium.

7. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments are equipped with a means of sending an auxiliary signal to indicate that a disconnection has been made.

8. Specific embodiments of the TPD as claimed in Claim 1 wherein the embodiments use available couplers mounted within a body containing the necessary additional features to provide the function of the TPD.

9. A TPD substantially as described herein with reference to Figures 1 - 4 of the accompanying drawing.