Cable Strain Relief Device

This invention relates to a device for preventing pulls on cables from being transmitted to associated connectors and for preventing the interference of the cables with other proximate structures such as cabinet doors.

The invention is particularly adapted for use with cabinet mounted electronic equipment wherein there is positioned a multiplicity of circuit boards which are connected to a plurality of input/output cables by means of electrical connectors. At the point of egress from the cabinet, damage may occur to the cabinet or to the cables when the cables are inadvertently pulled if the cables are not secured. In general the number of cables entering a cabinet is dependent on the particular configuration of the electronics mounted therein. The diameter of the cables may also vary, from cable to cable, as a function of the number and size of conductors per cable. An efficient strain relief device should therefore be able to restrain a variable number of cables having different diameters. In select applications it is also necessary to permit the removal of the circuit boards, or other electronic subsystem to which the connectors are affixed, with the connectors and cables remaining attached. Therefore, the strain relief device should also be able to release one or all of the cables without the need for disconnecting any connector.

The present invention derives its ability to accomplish the above desired results with a simple and efficiently configured device.

In accordance with the present invention, there is provided a rigid U-shaped bracket having its end portions projecting along a pivot axis which is substantially parallel to the bottom of the U-shape. Means are provided for pivotally mounting the bracket to a cabinet in a position proximate the cables and the electronic equipment serviced by the cables, such that the cables are positionable between the U-shaped member and a portion of the cabinet with substantially a 90.degree. bend. A pull on any cable positioned under the U-shaped member will cause the member to rotate around the pivot axis, toward the cabinet, creating a clamping action on the cable. The clamping action prevents the transmission of the pull to connectors connecting the cable to the equipment within the cabinet. In the absence of a pull, all of the cables are restrained in a secure position by the bracket to prevent interference with other portions of the electronic cabinet.

From the foregoing, it can be seen that it is a primary object of the present invention to provide a device for preventing the transfer of stress to cable-connected electrical connectors.

It is a further object of the present invention to provide an efficient and inexpensive device for protecting cables of differing size from physical damage.

It is another object of the present invention to provide a device which will quickly permit the release of all cables without requiring that the cables be disconnected from their associated electronic device.

These and other objects of the present invention will become more apparent and better understood when taken in conjunction with the following description and the accompanying drawings, throughout which like characters indicate like parts and which drawings form a part of the present disclosure.

FIG. 1 is a perspective view illustrating the preferred device in operating position within an electrical equipment cabinet;

FIG. 2 illustrates the preferred configuration of the device; and

FIG. 3 illustrates, partially in sectional view, the preferred device in its operating position for clamping cables in a secure position.

Referring to FIG. 1, the cable strain release device 30 is mounted within a cabinet 10. The cabinet 10 holds a number of electronic devices 14, which may be circuit boards, having electrical connectors 16 connected to one end. Each of the connectors 16 is in turn connected to at least one cable 18. The cables 18 are input/output cables which carry signals to and from the electronic devices 14 and which are routed through the device 30 and egress from the cabinet 10 through a defined space 48. The space 48 is defined by the bottom 20 of a cabinet door 12, and the top of a bottom rear cover 46. The cables 18 must be kept clear of the door 12 at all times to prevent chafing of the cables and possible damage to the door.

Referring to FIG. 2, the moving part of device 30 is a U-shaped bracket 50 having a base (top) portion 40, with two arm portions 38 extending 90.degree. from the base portion and two end portions 36 extending 90.degree. from the arm portions 38 along an axis which is substantially parallel to the base portion 40. The labeled axis C is the pivot axis about which the U-shaped bracket 50 will rotate. The bracket 50 is held along the axis C by a pair of brackets 32, each having a tab section 34 which engages an associated end portion 36 of the bracket 50. The dotted outline of bracket 50 shows its operating position in engagement with the brackets 32. The bracket 50 may be formed from a steel rod, giving it a circular cross-section.

Referring now to FIG. 3, the U-shaped bracket 50 is pivotally mounted to a sloping inner wall 44 of the cabinet 10 by the pair of brackets 32. The tab section 34 of each bracket 32 engages the associated end portion 36 of the U-shaped bracket 50 to form a bearing surface for pivoting bracket 50 about the axis C. The tab sections 34 extend less than half-way around the end portions 36 to facilitate removal of the bracket 50. The cables 18 are held in a non-interferring position by bearing against the base portion 40 of bracket 50. The force exerted by the cables maintains the end portions 36 in contact with the tab sections 34. As can be seen from the FIG. 3 drawing, if the U-shaped bracket 50 were not in place, the cables would chafe against the bottom 20 of door 12. With the bracket in place the cables are held in proximity to the surface 42 and the cabinet rear cover 46. The cable portion on one side of the bracket 50 is substantially perpendicular to the cable portion on the other side of the bracket. In operation, when a pulling force P is applied to a cable along the arrowed direction lines shown, the cable wants to pull out of the cabinet. In so doing, the cable, through friction, causes the bracket 50 to rotate in a clockwise direction, about the pivot axis C, further clamping the cables to the surfaces of members 42 and 46, thereby effectively isolating the force P from the connectors 16.

In order to remove a board 14 without disconnecting the connectors 16, the U-bracket 50 is pressed inward, along the action line labeled N, and the end portions 36 are cleared from engagement with the tab sections 34, one end at a time, and the bracket 50 is removed. The board and cables may then be removed from the cabinet. To re-insert the boards, the procedure is reversed.

As can be seen from the drawings, a plurality of cables of different diameters may be accommodated by the present invention.

While there has been shown what is considered to be the preferred embodiment of the invention, it will be manifest that many changes and modifications may be made therein without departing from the essential spirit of the invention. It is intended, therefore, in the annexed claims, to cover all such changes and modifications as fall within the true scope of the invention.