Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Reexamination Certificate
2001-04-12
2001-10-30
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
C174S064000, C174S135000, C248S056000, C439S583000
Reexamination Certificate
active
06310290
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to cable connectors and specifically to an improved cable connector that collapses easily to allow easy insertion in the knock-out of an electrical box, does not expand excessively in diameter upon cable insertion, and grips an inserted cable more securely than present art cable connectors of similar construction.
BACKGROUND OF THE INVENTION
Many varieties of cable connector are employed to connect electrical cables to junction boxes. The most traditional type of connector is barrel-shaped and constructed of metal. It consists of a front end that is threaded on its outer circumference and a rear end containing a hole formed laterally through the outer circumference of the connector. The hole in the rear end of the connector is threaded and fitted with a cable-securing screw that, in its unsecured position, extends slightly within the inner channel of the connector. The cable connector is typically secured at its front end to a junction box by inserting the externally threaded nose of the connector into a knockout hole in the junction box and then threading a nut tightly onto the nose portion. Electrical cable is then typically fed through the internal channel of the attached connector and the cable-securing screw is rotated until the cable is tightly secured against the far wall of the internal channel. Once tightened in this manner, the cable connector is secured to the junction box by the front threaded end and nut and the connector are secured to the cable by the cable-securing screw. Electrical connections later made within the junction box will therefore not be stressed or pulled loose by a rearward-pulling force on the electrical cable. This type of connection therefore provides strain relief to the interior electrical connections by relieving any stresses from rearward forces on the cable at the point where the cable-securing screw and bracket are affixed.
Other variations on this type of cable connector are those in which the rear or cable-securing end of the connector is a half-barrel or semi-circular shaped extension from the body of the barrel-shaped connector. Typically the semi-circular extension is tapped and threaded on both sides. A bracket containing holes on either end mates with the holes in the semi-circular extension. The bracket is held loosely to the semi-circular extension by screws and the screws may be advanced to tighten against a cable inserted within the channel of the connector and between the bracket and semi-circular extension of the connector. The screws may then be tightened thereby locking the cable with respect to the connector.
More recently, one-piece plastic cable connectors have been introduced. These connectors typically feature an integral clamping element that eliminates the need for a screw or screw and bracket combination to lock the cable in place. The connectors are designed to snap into an access hole in an electrical panel.
One such connector is described in U.S. Pat. No. 5,594,209 to Nattel et al issued Jan. 14, 1997. This patent describes a connector having a resiliently deflectable internal clamping element that has a single edge for gripping an inserted cable and at least one additional projection on the inner wall of the housing adjacent the clamping element to assist in clamping a cable. The connector also has a slot running along its entire length to facilitate its compression when inserting it into an electrical panel.
Another resilient one-piece connector is described in U.S. Pat. No. 4,970,350 to Harrington, issued Nov. 13, 1990, and describes a one-piece connector having an internal coupling means comprising a resiliently bendable flange for urging an inserted cable against the opposite inner wall of the channel. The flange may be provided with a pair of cable engaging tips to provide gripping engagement of the cable. A longitudinal slot extends along the entire length of the connector to facilitate its radial compression for insertion into an electrical panel.
Although the two aforementioned patents provide useful snap-in connectors for attaching cables to electrical panels, their design is not optimal as they rely upon a single surface to lock the cable in place. The reliance upon a single surface for gripping the cable also limited the aforementioned patents in the range of cable diameters that could be accommodated by the connector.
U.S. Pat. No. 6,177,633 to Gretz, issued Jan. 23, 2001 provided an improved cable connector that utilized a serrated engagement surface for retaining the inserted cable. The use of the serrated engagement surface provides a more secure gripping action on the inserted cable and has the additional benefit of being more readily adaptable to a larger variety of cable diameters without sacrificing cable retention capability.
The present invention improves upon the design of the flexible snap-in type cable connector described in U.S. Pat. No. 6,177,633, which is herein incorporated by reference. The connector of the present invention improves upon the design given in '633 by adding an integral bridge across the longitudinal slot. The bridge adds structural rigidity to the rear portion of the connector by preventing the rear channel of the connector from opening wider than a predetermined fixed amount determined by the length of the bridge. The bridge enables an installer to insert a cable within the connector, advance the cable the desired amount to provide sufficient cable to later make connections within the panel, and easily insert the connector into the panel. The bridge provides a pivot point that allows the nose portion of the connector to easily collapse allowing easy insertion into the panel or box.
A second improvement is achieved over the design given in '633 by providing a short slot on the front or nose end of the connector to further assist the front end of the connector in collapsing when pressed into the knockout of a panel or box.
An integral strut is provided between the flange and the interior wall of the channel in the present connector to further improve the design over the prior art in '633. The integral strut stiffens the flange and provides a more secure grip on an inserted cable.
ADVANTAGES
Several advantages of this invention over the prior art are:
(a) An integral bridge adds structural rigidity to the rear portion of the connector. When a cable is inserted within the connector, the bridge prevents the outward pressure exerted by the flange against the cable and channel wall from spreading the connector wider than desired.
(b) The bridge provides a pivot point that allows the nose portion of the connector to easily collapse allowing easy insertion into the panel or box.
(c) A short slot is provided on the front or nose end of the connector to further assist collapse of the front end of the connector when pressed into the knockout of a panel or box.
(d) An integral strut is provided between the flange and the interior wall of the channel to stiffen the flange and provide a more secure grip on an inserted cable.
These, and other advantages will become apparent in the attached drawings, the detailed description of the invention, and the appended claims.
REFERENCES:
patent: 5060891 (1991-10-01), Nagy et al.
patent: 5789705 (1998-08-01), Cancellieri et al.
patent: 6116945 (2000-09-01), Davis et al.
patent: 6133529 (2000-10-01), Gretz
patent: 3512577 (1986-10-01), None
patent: 2102637 (1983-02-01), None
patent: 2276777 (1994-10-01), None
Arlington Industries Inc.
Patel Dhiru R
Reichard Dean A.
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