TERMINAL CONNECTOR FOR A CIRCUIT BREAKER BACKGROUND OF THE INVENTION The present invention relates to circuit breakers, and more particularly relates to a circuit breaker device which assists in installation.
During installation of a circuit breaker, terminal straps extending from either a line side or a load side of a circuit breaker must be connected to its source or load (such as to bus lines or cable lines). Connection may be accomplished by inserting a screw, or other rod-shaped connector, through a hole in the terminal strap and through an opening in a connector for the source or load. A nut, or equivalent receiving or tightening device, may then be attached to the screw for securing the connection between the terminal strap and the source or load.
When a screw is used to make the above-described connection, holding a nut for assembly of the load/source connector to the terminal strap is awkward and labor intensive. In some instances, holding the nut by hand is practically impossible and an alternative assembly method must be selected.
Threaded terminal straps are prone to being stripped if the proper screw is not used or if it is over-torqued. If they are stripped, then the entire circuit breaker may need to be replaced (at significant expense) or an alternate fastening method may be required. Furthermore, threaded terminal straps use threaded holes which do not allow for any misalignment of parts.
Individual terminal nut retainers exist which connect with a circuit breaker. These are somewhat inconvenient to use since each one needs to be connected individually. In addition, access to the terminals is limited since additional plastic is required to give each individual nut retainer the proper support.
SUMMARY OF THE INVENTION
In an exemplary embodiment of the invention, a multipole termination connector for holding a plurality of screw apertures adjacent a plurality of terminal straps extending from a circuit breaker is disclosed. The multipole termination connector comprises a molded housing, a plurality of single-pole screw accepting members, each screw accepting member having a molded portion integrally formed with the molded housing and a screw receiving portion located on the molded portion. An aperture in preferably provided in each screw receiving portion and an attachment device preferably extends from the molded housing and is adapted to attach the multipole termination connector to a circuit breaker.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a top perspective view of a circuit breaker for receiving the multipole termination connector of the present invention; Fig. 2 shows a top perspective view of a multipole termination connector of the present invention; Fig. 3 shows a top plan view of the multipole termination connector of Fig. 2; Fig. 4 shows a bottom perspective view of the multipole termination connector of Fig. 2 before attachment to the circuit breaker of Fig. 1; Fig. 5 shows a top plan view of a multipole termination connector of the present invention having four pole screw receiving members; Fig. 6 shows a top plan view of the multipole termination connector of Fig. 5 with one screw receiving member removed; Fig. 7 shows a right end view of the multipole termination connector of Fig. 5; Fig. 8 shows a base side view of the multipole termination connector of Fig. 5;
Fig. 9 shows a connecting side view of the multipole termination connector of Fig. 5; Fig. 10 shows a side cross-sectional view of a single pole screw receiving member of the multipole termination connector of Fig. 5; Fig. 11 shows a top plan view of a circuit breaker load or line end with the terminal straps removed; Fig. 12 shows a side cross-sectional view taken along line 12-12 of Fig. 11 with the multipole termination connector of Fig. 5 connected to the circuit breaker of Fig. 11 ; Fig. 13 shows a top plan view of a screw accepting portion of a single pole screw receiving member for use with the multipole termination connector of Fig.
5 ; Fig. 14 shows a top plan view of a screw accepting portion of a single pole screw receiving member for use with the multipole termination connector of Fig.
5; Fig. 15 shows a partial and exaggerated top plan view of the opening of Fig. 14 before and after insertion of a nut therein; Fig. 16 shows a side cross sectional view of the single pole screw receiving member of Fig. 13; Fig. 17 shows a top plan view of a nut plate for use with the multipole termination connector of the present invention; and, Fig. 18 shows a side cross-sectional view of the nut plate of Fig. 17 within a single pole screw receiving member for a multipole termination connector of the present DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in Fig. 1, a multi-pole circuit breaker 10 is provided with a housing 12 including a top cover 14 through which an operating handle 16 may
extend. The housing 12 may be made from molded plastic. Extending from line side end 22 and load side end 20, is a plurality of upstanding walls 24,26, each extending from the housing 12 at an attached end 28 and to a free end 30. The walls 24,26 preferably extend substantially parallel to a sidewall 18 and substantially perpendicular to an end wall 19. Exterior walls 24 extend substantially continuously from sidewalls 18 (only one sidewall 18 shown) while spacer walls 26 are provided at equal intervals between exterior walls 24 to divide the width w between the exterior walls 24 into three substantially equal segments. It should be noted that more spacer walls 26 could be used with a greater spacing between exterior walls 24 to create more segments for additional poles in the circuit breaker if desired.
The circuit breaker 10 shown in Fig. 1 is a three pole circuit breaker and is thus provided with three terminal straps 32 extending from the circuit breaker interior. Each terminal strap 32 is provided with a screw hole for accepting a screw, or equivalent rod connector, to connect the terminal strap 32 with a connector end of a source or load (not shown).
In order to secure the connection of the screw to the terminal strap 32 and associated source or load connector, a multipole terminal connector 40 may be used as shown in Fig. 2. The multipole terminal connector 40 includes a plurality of single-pole screw accepting members 42 extending from a molded housing 44. The molded housing 44 is preferably molded from an insulative material such as plastic and includes a base portion 46 having a length 1 which is dimensionally as great or greater than the width w of the circuit breaker 10.
Integral with the molded housing 44 are molded portions 48 of each screw accepting member 42. The screw accepting members 42 further includes a screw receiving portion 50. As shown in Figs. 2 and 3, the screw receiving portion 50 may include a nut receiving plate 52 which may be integrally formed with the molded portion 48. The nut receiving plate 52 includes an aperture 53 having a hexagonally shaped opening 54. The opening 54 may have one or more longitudinal ribs or bumps 56 in its corner portions 55. The bumps 56 provide the received nut 60 with a snug interference fit. The aperture 53 may further have a circular recess 58
below the hexagonally shaped opening 54 for receiving a stem of a screw (not shown). A platform 57 may be provided between the opening 54 and the recess 58 and for supporting the received nut 60.
The screw receiving portion 50 includes a top surface 62 and a bottom surface (not shown), with the aperture 53 extending from the top surface 62 to the bottom surface. Below the bottom surface is an electrically insulative pocket 64, a bottom portion of which is shown in Fig. 4. The electrically insulative pocket 64 prevents a received screw stem from going to ground.
As further shown in Fig. 4, the molded housing 44 may include a plurality of apertures 66, six in total, which surround the aperture 53 providing a substantially constant wall thickness of structural walls 68. This arrangement saves on plastic material while providing the necessary structural rigidity and maintaining an aesthetically pleasing appearance. A line of perforations 82 preferably extends through the molded housing 44 between at least two adjacent single pole screw receiving members 42. Thus, the multipole termination connector 40 may be molded as a unit with more than one pole where one of the poles may be broken off along the line of perforations 82 if it is not needed. For example, a four pole termination connector 40 as shown may have one of the poles broken away so that it can be used on the three pole circuit breaker 10. This arrangement allows a single termination connector mold to make parts for multiple breaker configurations. Although only one line of perforations 82 is shown, it should be understood that a line of perforations 82 could be provided between each single pole screw receiving member 42.
Furthermore, although multipole termination connector 40 is shown with four poles, it is within the scope of this invention to mold the termination connector of the present invention with more or less poles.
Referring now to Figs. 2 and 4, an attachment device for connecting the multipole terminal connector 40 to the circuit breaker 10 is shown. The attachment device may include a groove 70 and indent 72 on each side of each molded portion 48 for slidable and snap-fit engagment with a rib 74 and tab 76 protruding from each upstanding wall 24,26. Each wall 24,26 may be provided with
a ledge 78 for abutting engagement with a stop wall 80 formed on the molded housing 44 adjacent each molded portion 48. When the multipole terminal connector 40 is to be attached to the circuit breaker 10, one single pole screw receiving member 42 is aligned for each terminal strap and then slid in the direction indicated by arrow A with the groove 70 fitting over rib 74 until the tab 76 snaps into the indent 72 which corresponds to when the ledge 78 abuts with stop wall 80.
Standard nuts for use with the present invention in its intended marketplace include both metric nuts and English nuts. One difference between a metric nut and an English nut is a slight difference in the dimension across the"flats", that is, the distance from one hexagonal side of the nut to an opposite side of the nut.
Also, the threading of an English nut and a metric nut may be slightly different. In one embodiment, the bumps 56 could be provided in each corner of the hexagonal shaped opening 54 to allow for an adjusted fit for either an English nut or a metric nut.
In another embodiment, as shown in Fig. 5, a multipole termination connector 90 may include a molded housing 92 having a plurality of single pole screw accepting members 94 extending therefrom. The screw accepting members include a molded portion 96 integral with the molded housing 92 and a screw receiving portion 98 having an aperture 100 therein. The aperture 100 is designed to accept either English standard nut hardware or metric standard nut hardware. The aperture 100 is formed from two overlapping hexagonal'recesses to receive the standard nut hardware, where the two hexagonal recesses are rotated approximately 30-degrees from each other. The resultant aperture 100 thus includes a 24 sided opening. A first hexagonally shaped opening 102 is appropriately dimensioned to receive metric standard nut hardware, and the second hexagonally-shaped opening 104 is appropriately dimensioned to receive English standard nut hardware. One of the"points"106 of either the metric or English hexagonal recesses 102,104 is identified in the screw receiving portion 98 by alphanumeric character 108 identifying it as being the appropriate hexagonal recess for that particular standard nut hardware. For example, as shown in Figs. 5 and 6, the letter"M"is used to identify the hexagonally shaped opening 102 as shaped to accept metric standard nut
hardware. The other hexagonal recess 104,30-degrees rotated, would then be the appropriate hexagonal recess for the other standard nut hardware (in this case English).
As shown in Figs. 8-9, the aperture 100 may further include a circular recess 110 below the 24 sided opening formed by hexagonal recesses 102,104. The circular recess 110 may receive a stem of a screw (not shown). A platform 112 may be provided between the opening 102-104 and the recess 110 for supporting a received nut (not shown). An electrically insulative pocket may be formed below the recess 110 for preventing the screw from going to ground. In some embodiments, where the screw may need to be attached by passing the stem through first the recess 110 and then the recesses 102-104, such as when the multipole termination connector 90 is to be attached from the backside of the circuit breaker 130, the recess 110 may pass all the way through the molded portion 96 rather than having a closed electrically insulative pocket.
As with multipole termination connector 40, the multipole termination connector 90 may include at least one line of perforations 82 within the molded housing 92. Thus, a four pole termination connector as shown in Fig. 5 could easily be converted to a three pole termination connector as shown in Fig. 6 by knocking off the leftmost single pole screw receiving member 92 along the line of perforations 82 which serves as a weakened connection area.
As further shown in Figs. 5-6, an attachment device for connecting the multipole termination connector 90 to the circuit breaker 130 (Fig. 11) is shown as including a dovetail projection 120 extending from the molded housing 92 between each single pole screw receiving member 92. As shown in Figs. 7-9, the dovetail projection 120 preferably extends the height h of the multipole termination connector 90. As shown in Fig. 11, the circuit breaker 130 may be provided with a correspondingly shaped dovetail recess 132 within spacer walls 134 such that the dovetail projection 120 may be slidably received within dovetail recess 132.
An additional attachment device for connecting the multipole termination connector 90 to the circuit breaker 130 is shown in Figs. 5-10 as flange 140. As most clearly shown in Fig. 10, flange 140 extends from the molded portion 96 at an attached end 142 to a free end 144. The free end 144 is separated from the top of the molded portion 96 and adjacent the screw receiving portion 98 by a gap 146 which may be reduced when the free end 144 is pushed towards the screw receiving portion 98. With reference to Figs. 10-12, as multipole termination connector 90 is pushed into the circuit breaker 130 by sliding the dovetail projection 120 into dovetail recess 132, the flange 140 abuts against the projection 150 extending from spacer walls 134 and compresses until the free end passes the projection 150, at which point the flange 140"snaps"back to its biased position shown in Fig. 10. The multipole termination connector 90 is thus retained within the circuit breaker 130. A support shelf 152 may be formed by projections extending from the spacer walls 134 to properly align the screw receiving portions 98 with the terminal straps (not shown) of the circuit breaker 130.
Referring now to Figs. 13 and 16, the aperture 100 may be provided with interference ribs 156 for providing a snug fit between the received nut and the aperture 100. As a nut (not shown) is pressed into the aperture 100, a portion of the rib or ribs 156 may be scraped off and forced downwardly. In order for the nut to maintain a proper fit against the platform 112, the debris from the scraped off portions of rib or ribs 156 must be removed from the aperture 100. As shown in Fig.
16, a clearance pocket 158 is provided directly below each rib 156 (where both rib 156 and clearance pocket 158 are exaggerated in size for clarity). Phantom line 156' indicates where the rib 156 has been scraped off and its debris or scraped off portion has been deposited within the pocket 158.
Referring to Fig. 14, one or more sawcuts 160 may extend from intersecting points 162 between the hexagonally shaped opening 102 and hexagonally shaped opening 104. As shown in Fig. 15, when a nut is pressed into the aperture 100, the material, such as plastic, forming the connector 90 moves from the solid lines 164 to the dashed lines 166, and closing the gap 168 formed by the sawcuts 160.
The sawcuts 160 thus provide a relief fit to a retained nut for preventing the material of the connector 90 from cracking.
Turning now to Fig. 17, a nut plate for use with a multipole terminal connector of the present invention comprises a metallic plate 170 having a threaded opening 172. Separate nut plates could be provided for metric threads and English threads. The nut plates may then slide into grooves 174 in a single pole screw receiving member as previously described. Alternatively, the nut plates 170 could snap or press fit into a molded portion of a termination connector. The use of a nut plate 170 eliminates the need for separate standard nuts. In addition, the nut plate 170 could be provided with some leeway in movement to compensate for misalignment.
The multipole termination connectors of the present invention provides support for preventing terminal straps in circuit breakers from bending since the connector provides support under each strap. In addition the termination connector also provides structural support when installing cable or bus conductors and when torquing the terminal straps. Additionally, the multipole termination connectors of the present invention provides support for the terminal straps under short circuit conditions where high magnetic forces are exerted between adjacent straps.
The termination connector of the present invention may be inserted from the bottom or top of the breaker. Additional variants would be to have clearance for connect on top and bottom. Clearance could either be variable or stopped by mechanical interference.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
