Electrical connector bushing

#The present invention is generally directed toward an electrical bushing to be used in electrical cable fittings. More specifically, it is directed toward an electrical cable restraint device that uses solid particles to enhance its restraint capabilities.

#An electrical fitting is usually required at installations where a flexible electrical cable must pass through an opening in a hard surface, such as into an enclosure, through a bulkhead, or into a rigid conduit. The electrical fitting is intended to form a firm mechanical grip on the cable to prevent it from sliding in or out of the opening through which it passes. Typically, it also reduces strain on the cord and on any connections within the fixture.

#Most strain relief electrical fittings on the market today consist of a threaded body, a deformable bushing, a slip ring, and a threaded gland. The deformable bushing compresses around the outer jacket of an electrical cable as the threaded body and threaded gland on either side of the deformable bushing are screwed together. As the bushing is compressed in an axial direction, its inner diameter decreases, causing the bushing to push inwardly on the electrical cable. If the electrical fitting is tightened sufficiently, the pressure of the bushing on the cable creates enough friction force to prevent the cable from sliding through the fitting. However, if the threaded gland is not tightened onto the threaded body sufficiently, the cable can be pulled loose, potentially causing an electrical short.

#Further advantages of the invention will become apparent by reference to the detailed description of preferred embodiments when considered in conjunction with the drawings:

#FIG. 1 depicts a typical electrical fitting.

#FIG. 2 illustrates another variation of an electrical fitting.

#The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. Various modifications to the preferred embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein.

#Referring now to FIG. 1 and FIG. 2, in a typical electrical fitting, threaded gland 2, which may include a slip ring 3 (or chuck 4, as shown in FIG. 2) is pushed over cable 1. Cable 1 is then passed through bushing 5 and finally through a threaded body 6. As threaded gland 2 is tightened around threaded body 6, threaded gland 2 pushes against slip ring 3 to apply pressure in an axial direction against bushing 5, causing it to deform and press against cable 1. The pull-out performance of the electrical fitting is dependent upon the force of the bushing 5 against the outer jacket of the cable 1.

#As will be appreciated from FIG. 3, in the presently claimed invention, the inner surface of bushing 5 includes a textured area 7. The textured area 7 increases the coefficient of friction of the inner surface of the bushing. As a result, bushing 5 does not require as much force to prevent cable 1 from moving compared to prior art bushings. The lower force of bushing 5 will also reduce the torque required on threaded gland 2 as it is tightened onto threaded body 6. Most importantly, the pull-out performance, which is the ability of the electrical fitting to resist forces pulling the cable from the fitting, is increased.