METHOD AND APPARATUS FOR REMOVABLY LOCKING A CONDUIT

INTO A FIXED POSITION

Technical Field

This invention relates generally to removably locking a device and more specifically to locking an end of a conduit and/or an adapter to a box or like device.

Background Art

Existing locking nuts used today to fasten wiring conduits and/or adapters to generator terminal boxes, junction boxes and power distribution boxes are awkward to use. For example, the conventional locking nut must be slid along a bundle of electrical wires which have terminals attached at an end and are secured in the bundle by several tie wraps. The wire wraps and terminals tend to catch on the locking nut making the task more difficult to perform, increasing the time and cost of assembly. At times, the sliding of the locking nut along the bundle may result in scuffing, scrapping or cutting of the insulation on the electrical wires reducing the reliability of the insulation and causing premature failure. On the other hand the use of multi-piece nuts can result in lost or misplaced pieces which make up the entire nut, thus, the end result being lost time in assembly and increased cost.

U.S. Pat. No. 4,047,743 to Burton L. eintraub issued September 13, 1977, discloses an example of one such locking nut as described above. The locking nut disclosed is of a conventional design. The locking nut includes an

external octagonal shaped outer periphery forming a structure enclosure. The nut further includes an internal thread for assembling onto a conduit or adapter. The octagonal shape is provided so that a wrench or another tool can grip the surface and tighten the locking nut thereon.

U.S. Pat. 3,843,169 to Carleton H. Wise issued October 22, 1974, discloses a coupling device having locking nuts thereon. The locking nuts are of a conventional design. The locking nut includes an external octagonal shaped outer periphery forming a structure enclosure. The nut further includes an internal thread for assembling onto a conduit or adapter. The octagonal shape is provided so that a wrench or another tool can grip the surface and tighten the locking nut thereon.

Another example of a conventional locking nut is disclosed in Great Britain Pat. No. 2,121,134 issued October 23, 1985, to Hop Lee. The electrical connector box disclosed includes a nut having an outer periphery forming an enclosure, an internal thread and external flats to be gripped by a wrench or another tool for tightening the locking nut.

U.S. Pat. 4,078,470 issued March 14, 1978, to Paul S. Zeramick, Jr. discloses a split nut which may be readily pulled apart laterally and reclamped or reassembled on any other longitudinal portion of the screw threaded rod. The internally threaded nut is split longitudinally into complementary halves along a vertical flat plane extending to an intermediate portion of the height of the nut. From the intermediate portion, the split follows along flat planes extending at an acute angle to the horizontal to provide interlocking against direct horizontal

separation but being freely separable laterally along the acute angle.

Disclosure of the Invention In one aspect of the invention, a one-piece locking nut comprises a generally open ended ring shaped member having a pair of ends spaced a preestablished distance one from the other, a mounting surface thereon, an outer profile having a gripping shaped surface thereon, and an inner generally cylindrical surface having threads therein.

In another aspect of the invention, a locking nut has been adapted for use with a conduit system. The conduit system comprises a box having a side wall, the side wall has an inside surface, an outside surface and a hole extending through the side wall and exiting each of the surfaces. The hole has a preestablished diameter and one of a piece of conduit and an adapter have a threaded end, the threaded end is positioned in the hole and extends beyond the inside and outside surfaces. A means for abutting one of the conduit and the adapter in contact with the outside surface of the box. The one-piece nut has a pair of ends spaced a preestablished distance one from the other, a mounting surface thereon, an outer profile having a gripping shape surface thereon, and an inner generally cylindrical surface having threads therein and when used with the conduit system partially encircling one of the adapter and the conduit and having the mounting surface in contact with the inside wall of the box.

In another aspect of the invention, a method of assembling a one-piece locking nut having a pair of ends spaced one from the other on one of a conduit and an adapter, each having a wire bundle therein is

disclosed. The conduit or the adapter have a threaded end thereon and an abutting portion thereon. One of the conduit and the adapter is removably attached to a box. The box has a side wall and the side wall has an inside surface, an outside surface and a hole extending through the side wall and exiting each of the surfaces. The improvement comprises the following steps: positioning one of the adapter or the conduit through the hole in the side wall of the box; abutting the abutting portion with the outside surface of the side wall of the box; positioning the spaced apart ends of the locking nut over the wire bundle near one of the conduit and the adapter; moving the locking nut into contact with the threaded end of one of the conduit and the adapter; and tightening the locking nut on the threaded end until the nut is in contact with the inside surface of the side wall of the box.

Brief Description of the Drawings Fig. 1 is an end view of a one piece locking nut having a pair of ends spaced a preestablished distance apart;

Fig. 2 is a sectional view of a portion of a conduit system taken along the axis of a wire bundle wherein an adapter is positioned on an end of a piece of conduit; and

Fig. 3 is a sectional view of a portion of a conduit system taken along the axis of a wire bundle wherein a piece of conduit has a threaded end and a nut thereon.

Best Mode for Carrying Out the Invention

In reference to FIGS. 1 and 2 a conduit system 10 is partially shown. The conduit system includes a conduit 12 which as an alternative may

include an adapter 14, a box 16 of which only a portion is shown, a wire bundle 18 and a one-piece locking nut 20. The wire bundle 18 includes a plurality of insulated electrical transmitting wires 22 retained in the bundle by a plurality of tie wraps 24 of which only one is shown. The wire bundle 18 is positioned in the conduit 12.

The box 16 which in this application is an enclosure for a generator includes a pair of side walls 30 of which only one is shown, and a top and a bottom which are not shown. The side wall 30 has an inside surface 32, an outside surface 34 and a hole 36 extending through the side wall 30 and exiting the inside and the outside surfaces 32, 34. The hole 36 has a preestablished diameter.

The conduit 12 is of a conventional design and can be made of a metallic or plastic material. As best shown in FIG. 3, the conduit 12 includes a nominal preestablished diameter which is slightly smaller that the preestablished diameter of the hole 36 in the side wall 30 of the box 16. When the conduit is used without the adapter 14, the conduit 12 includes at least one threaded end 40 and a standard locking nut 42. The locking nut 42 has an abutting surface 44 thereon and is threadedly attached on the threaded end 40 forming an abutting means 46 on the conduit 12. When the conduit 12 includes the adapter 14, as best shown in FIG. 2, the threads are provided on the end of the adapter 14. The adapter 14 includes a pair of ends

50,52, one of which is threaded, a raised portion 54 intermediate the ends 50,52 and an abutting surface 56 on the raised portion 54 which is also a part of the abutting means 46 when the adapter 14 is used. The end 52 which is not threaded is adapted to be attached

to the conduit 12 in a conventional manner. For example, in this application the end 52 includes an enlarged bore 58 which is sized to fit over and around the conduit 12. A threaded hole 60 is positioned near the end 52 and has a set screw 62 positioned therein. When the set screw 62 is tightened, the adapter 14 is secured on the conduit 12 in a fixed position.

The one-piece locking nut 20 includes a generally open ended ring shaped or arcuate shaped member 70 having a pair of ends 72,74 spaced a preestablished distance one from the other. The nut 20 further includes a pair of side walls 76,78 each having a mounting surface 80 thereon. An outer profile 82 has a gripping surface 84 thereon and an inner generally cylindrical surface 86 having threads 88 therein. The gripping surface 84 in this application includes a plurality of raised portions 90, as best shown in FIG. 1, positioned in a generally uniform array about the extremity of the arcuate member 70. As an alternative, not shown, the gripping surface 84 could include a plurality of flats arranged in a generally hexagonal pattern or any configuration which would provide a gripping feature for tightening the locking nut therewith. The spacing between the ends 72,74 is measured in an arcuate distance. For example, the angle resulting in the preestablished distance ranges from an angle of about 120 degrees to about 80 degrees. The ideal angle in this application has been established as being 80 degrees. This angle provides a sufficiently large opening between the ends 72,74 through which the wire bundle 18 can pass and still provides the functional characteristic of locking the conduit 12 to the box 16. For example, the most ideal functional characteristics of the one-piece locking nut 20 exists when the distance

between the ends 72,7'4 is the smallest. However, a compromise must be made to prove an opening between the ends 72,74 through which the wire bundle 18 can pass. The greater the angle between the ends 72,74 the greater the tendency of the one-piece locking nut 20 to deflect and the greater the holding capability is reduced. It has been determined that an angle greater than 120 degrees will result in an opening which will not sufficiently lock the conduit 12 to the box 16.

Industrial Applicability

In this application, the conduit system 10 is used to attach the conduit 12 to the side wall 30 of the generator enclosure and thus protect the electrical transmitting wires from external damage. When using only the conduit 12, rather than the piece of conduit 12 with the adapter 14 attached thereto, the threaded end 40 of the conduit has the standard locking nut 42 threadedly attached thereto. The conduit 12 has the wire bundle 18 preassembled therethrough. The conduit 12 is inserted into and through the hole 36 in the side wall 30 of the generator enclosure. The abutting surface 44 of the standard locking nut 42 is positioned in contacting relationship to the outside surface 34 of the side wall 30. The spaced apart ends 72,74 of the one piece locking nut 20 is positioned over the wire bundle 18 and the locking nut 20 is threadedly engaged on the threaded end 40 of the conduit 12. The gripping surfaces 84 on the one-piece locking nut 20 are used to tighten the nut 20 on the threaded end 40 to fixedly position the conduit 12 in the box 16.

When using the adapter 14 with the conduit 12, the enlarged hole portion 58 is positioned over

one of the unthreaded ends of the conduit 12 and the set screw 62 is tightened so that the adapter 14 is removably attached to the conduit 12. The wire bundle 18 is inserted into and through the conduit 12 and the adapter 14. The adapter 14 is inserted into and through the hole 36 in the side wall 30 of the generator enclosure. The abutting surface 56 of the adapter 14 is positioned in contacting relationship to the outside surface 34 of the side wall 30. The spaced apart ends 72,74 of the one-piece locking nut 20 is positioned over the wire bundle 18 and the locking nut 20 is threadedly engaged on the threaded end 50 of the adapter 14. The gripping surfaces 84 on the one-piece locking nut 20 are used to tighten the nut 20 on the threaded end 50 to fixedly position the adapter 14 and the conduit 12 in the box 16.

Thus, the one-piece locking nut 20 with its spaced apart ends 72,74 eliminates the scuffing and cutting of the insulation on the electrical conducting wires 22 in the wiring bundle 18. Since the nut 20 does not need to be slid over the tie wraps 24 and along the length of the wire bundle 18, assembly time and reliability of the installation is improved. These improvements reduce cost and down time, thus providing an improvement over the state of the art for removably attaching and locking a conduit 12 into a fixed position.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.