Electrical Raceway With Improved Ground Connection Method and Apparatus

1. Field of The Invention

This invention relates to a method and apparatus of grounding a cable in an electrical conductive raceway and the raceway for use in an interior wall system by forming a crimp section in the wall of the raceway, and then crimping a bare, or partially bare, cable or wire directly to the wall With the crimp section.

2. Description of Related Art

U.S. Pat. No. 4,367,370 discloses an interior wall system used for dividing offices and other interior regions into smaller work areas. These prior art systems include a plurality of prefabricated panels releasably joined together and individually electrically prewired to facilitate supplying electrical energy to areas bounded by the wall system.

One necessary aspect of the wall panel is the grounding system for the metal parts. For reasons of safety and prevention of electrical short circuits, a raceway encloses the power cable. When the raceway is made of metal, it must be grounded. U.S. Pat. No. 4,429,934 discloses one method of providing a ground using a ground clip. This prior art clip is clipped to the ground wire of the cable and is hooked over the edge of the wall of the raceway making electrical contact thereto. This grounds not only the raceway but also the panel sections in electrical contact with the raceway. U.S. Pat. No. 4,577,055 discloses a method of attaching a ground wire to a metal frame by using a screw and washer or a screw and ring terminal.

Although the prior methods of attaching the metal raceway to the ground have worked well, an attempt has been made to make the connection less costly from both a material and a labor standpoint. To take advantage of the labor savings provided by machinery production of this ground connection, a metal rivet has been used to attach an insulation displacement terminal or a ring terminal to the metal base. With one additional step, the ground is attached to either of these terminals. In both of these methods of ground connection, although time is saved, an extra terminal is needed to connect the wire to the metal base. This use of additional terminals adds to cost and creates the potential for inventory control problems.

In the present invention a prewired electrical subassembly is disclosed having a ground wire connected to an elongated metal raceway by crimping means stamped and/or formed unitarily with the raceway. The invention also is directed to a method of making this novel subassembly. The method includes the steps of: forming a unitary metal raceway with a ground contact means therein; locating a ground wire within the portion of the raceway having the ground contact means; moving at least portions of the raceway and/or the ground wire for forming a permanent electrical connection between the ground wire and the raceway.

The invention further is directed to an apparatus for carrying out the above described method.

These, and other objects and advantages of the invention, will be more fully understood and appreciated by reference to the accompanying drawings and written description of the preferred embodiment.

FIG. 1 is a perspective view of the wall panel illustrating the location of the raceway in the panel.

FIG. 2 is a perspective view of the preferred embodiment of the raceway in the holding fixture before the bared ground wire is crimped.

FIG. 3A is a perspective view of the raceway in FIG. 1 before the arms of the crimp are forced down upon the ground conductor wire. FIG. 3B is a perspective view of the raceway in FIG. 1 after the raceway is rotated into a vertical position shown in FIG. 2.

FIG. 4 is a top view of the raceway.

FIG. 5 is a cross sectional view of the crimp section taken along lines 55 of FIG. 4.

FIG. 6 is a top view of the raceway mounting cap.

FIG. 1 illustrates a wall system 10 formed by a series of interconnected upright prefabricated wall panels, only two substantially identical panels 11 and 12 being illustrated. Panels of different lengths can be interconnected.

Each panel, such as panels 11 and 12, include an internal rigid, rectangular frame formed by parallel top and bottom rails rigidly joined together by parallel side rails. These rails are of channel shaped configuration and open inwardly of the panel, whereby the frame confines a suitable core structure, normally a honeycomb layer or similar conventional structure. The core and frame are normally sandwiched between thin facing sheets disposed on opposite sides of the frame. These sheets are normally covered by a suitable fabric which define the exterior side faces of the panel.

The panels 11 and 12 are provided with a prewired electrical assembly 13 extending longitudinally along the lower edge thereof. This system includes identical power blocks 14 and 15 disposed adjacent the opposite lower corners of the panel. The power blocks 14 and 15 are individually electrically connected by a multiconductor cable 16 or separate wire conductors. One of the conductors defines a ground 33. The cable 16 and the ground 33 extend between the power blocks 14 and 15 through an elongated, closed channel 17. This latter channel 17 extends between and ridgedly joins the housings of the power blocks 14 and 15 together. The channel 17 is in turn fixedly, but releasably, connected to the bottom rail of the frame by means of locking handles 18. Locator arms 29 locate the assembly 13 in lateral and longitudinal relationship with the bottom of panels 11 and 12.

The closed channel 17 is formed by an elongated open topped raceway 19 and a cover 20 which is engageable with the raceway 19. The closed channel 17 is dimensioned to permit the cable 16 and ground 33 to pass therethrough. More particularly, the raceway 19 includes a generally planar longitudinally extending bottom wall 22, and flanges 23 and 24 which extend outwardly from portions of the bottom wall 22. The flanges 24 and 23 define portions of the raceway 19 to which the cover 20 is attached. The raceway 19 is stamped and formed to define a wire crimping portion 21, numerous holes including pilot hole 28, locator arms 29, and spacers 27. As shown most clearly in FIGS. 2 and 3, the wire crimping portion 21 is stamped and formed as one piece with raceway 19 to define a pair of crimping arms 30 which extend generally perpendicularly from the plane of the bottom wall 21 of the raceway 19.

The raceway 19 with the power blocks 14 and 15 placed on spacers 27, cable 16 and ground 33 are initially positioned as illustrated in FIG. 3A in a fixture apparatus 40 (not shown completely in FIGS. 3A and 3B), which is mounted in proximity to a crimp press 35. The fixture apparatus 40 includes a sliding raceway mount 31 having a locating channel 36 for receiving the raceway 19 therein. The sliding raceway mount 31 is slidably movable along parallel rods 38 and 39 for slidable movement toward and aWay from the crimp press 35. The sliding raceway mount 31 of the fixture apparatus 40 further includes a fixed wire guide 34 extending generally perpendicularly therefrom at a location slightly spaced from the channel 36 for holding the cable 16 aWay from the raceway 19. Referring to FIGS. 3A and 3B, the assembly of the raceway 19, power blocks 14, 15, cable 16 and ground 33 is positioned such that the raceway 19 and the ground 33 are disposed between the fixed wire guide 34 and the locating channel 36 in the fixture apparatus 40. The cable 16 without ground 33 is disposed on the side of the fixed wire guide 34 opposite the locating channel 36. The raceway 19 and power blocks 14, 15 are then rotated approximately 90 degrees about the longitudinal axis of the raceway 19 such that the raceway 19 becomes positioned in the locating channel 36 of the fixture apparatus 40. However, as shown in FIG. 3B, the cable 16 will remain spaced from the ground wire 33 by the fixed wire guide 34.

Again referring to FIGS. 3A and 3B, it will be appreciated that proper lateral and longitudinal alignment of the raceway 19 in the fixture apparatus 40 is important for achieving proper crimping of the arms 30 of the crimping portion 21 to the ground 33. This proper alignment and positioning is achieved by a pilot locator stud 42 (not shown) which extends from the locating channel 36 of the fixture apparatus 40 for engagement with the pilot hole 28 in the bottom wall 22 of the raceway 19.

The fixture apparatus 40 further includes a wire clamp 37 mounted thereto in proximity to the pilot locator stud 42 (not shown) which engages the pilot hole 28 and the fixed wire guide 34, as shown most clearly in FIG. 2. The clamp 37 is operative to securely engage and retain the ground 33 in a position intermediate the arms 30 Of the crimping portion 21. As illustrated in FIG. 2, the clamp 37 is manually engageable and releasable. However, it is to be understood that more automated clamping means may be provided.

The clamp 37 is activated to securely retain the ground 33 between the crimp arms 30.

After actuation of the clamp 37, the operator of the apparatus initiates a cycle by depressing the activation buttons 32. This activation generates a slidable advancement of the fixturing apparatus 40 along the rods 38 and 39 and toward the crimp press 35. The proper positioning of the fixturing apparatus 40 relative to the crimp press 35 is sensed by appropriate electro-mechanical or optical sensing means incorporated into the crimp press 35. Upon this proper alignment of the fixturing apparatus 40 in the crimp press 35, a crimping cycle is commenced to urge the arms 30 of the crimping portion 21 downwardly toward the bottom wall 22 of the raceway 19 and into secure crimping engagement with the ground 33. Upon completion of this crimping cycle, the fixturing apparatus 40 is moved away from the crimp press 35 along the rods 38 and 39 into a position where the operator of the apparatus can release the clamp 37 and urge the cable 16 into the raceway 19. The cover 20 is then fastened to the raceway 19 to complete the pre-wired electric subassembly 13. The subassembly 13 is then removed from the fixturing apparatus 33 to enable positioning of another raceway subassembly therein.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustration purposes, it will be recognized that variations or modifications of the disclosed apparatus including the rearrangement of parts are within the scope of the present invention.