Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Reexamination Certificate
1999-07-06
2001-10-09
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
C174S15300A, C052S716100
Reexamination Certificate
active
06300568
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a grommet strip for covering an exposed edge of a wall and, more particularly, to an electrically insulating grommet strip for covering the exposed edges of openings in electrical equipment housings.
Electrical equipment housings frequently possess openings for the passage of electrical wires. Generally, such openings are equipped with grommets or bushings that cover and insulate the exposed edges of the openings. A common grommet is made of rubber or a similar resilient material and consists of a pair of annular spaced apart flange portions internally joined by a cylindrical portion. The cylindrical portion projects through an opening and the flange portions engage the peripheral wall portions thereof. Disadvantages of such grommets include the requirement for large inventories to accommodate openings of various size, and their inapplicability to openings of other than circular shape.
The above problems are somewhat alleviated by a grommet strip having a flat, elongated base from opposite edge of which project longitudinally spaced apart pair of fingers. The strip can be cut to desired length and then applied to an opening with the base engaging the edge of the opening and the fingers engaging peripheral portions thereof. Such a grommet strip is disclosed in British Patent No. 849,761. However, certain disadvantages persist for even the above described grommet strip. For example, the installation of the grommet strip into openings of complex shape requires the use of an adhesive and is, therefore, quite labor intensive.
Improved grommet strips are disclosed in U.S. Pat. Nos. 4,769,966 and 5,343,669. Those grommet strips comprise resiliently coated spring tempered substrate strips which can be securely mounted over an exposed edge of a wall without the use of adhesives. However, the multiple-axis flexibility of the grommet strips is limited so as to prevent their use over openings formed by non-cylindrical, tubular wall sections used in applications such as aircraft.
The object of this invention, therefore, is to provide an improved grommet for covering the exposed edges of openings in electrical housings.
SUMMARY OF THE INVENTION
The invention is a grommet strip including a metallic, elongated base having first base portions spaced apart along a longitudinal axis and each having a given width W; and second base portions each joining a longitudinally spaced apart pair of the first base portions, each of the second base portions having a width substantially less than W so as to allow bending of the elongated base in orthogonally related directions about the longitudinal axis.
Also included are first fingers extending upwardly from longitudinally aligned first edges of at least some of the first base portions; and second fingers extending upwardly from longitudinally aligned second edges of at least some of the first base portions. The first edges are substantially transversely aligned with the second edges; and the first fingers, the second fingers and the base form a longitudinally extending channel for receiving an edge portion of a wall. A non-metallic coating is secured to a bottom surface of the base. Because of its multiple axis flexibility, the grommet strip can be secured over the edge of openings terminating non-cylindrical, tubular wall portions.
According to one feature of the invention, the second base portions have a uniform width w. This feature provides the strip with longitudinally uniform gripping characteristics.
According to other features of the invention W is at least two times w, and preferably at least three times w. The reduced relative widths of the second base portions enhance desired multiple axis flexibility of the strip.
According to another embodiment of the invention, the second base portions are longitudinally aligned with the longitudinal axis. This embodiment exhibits uniform flexibility in opposite transverse directions.
According to another embodiment of the invention, the second base portions are transversely spaced from the longitudinal axis. Transverse spacing of the second base portions facilitates selection of transverse flexibility characteristics of the grommet strip.
According to one feature of the above embodiment, the second base portions are transversely spaced in alternating opposite directions from the longitudinal axis. This feature establishes uniform transverse flexibility in opposite directions.
According to another feature of the above embodiment, all of the second base portions are transversely spaced in the same direction from the longitudinal axis. This feature provides enhanced transverse flexibility in a transverse direction opposite to the same direction of second base portion spacing.
According to yet another feature of the invention, a first finger extends upwardly from each of the first edges, a second finger extends upwardly from each of the second edges, and the first and second fingers are transversely aligned. These features enhance gripping strength of the grommet strip.
According to additional features of the invention, each of the fingers has a lower portion joined to one of the edges, and an upper portion extending upwardly from the lower portion, the lower portion is bent into the channel, and the upper portion is bent away from the channel so as to provide the finger with a V-shaped section. These features further enhance the gripping forces provided by the grommet strip.
REFERENCES:
patent: 3934385 (1976-01-01), Paulus et al.
patent: 4769966 (1988-09-01), Petri
patent: 5343669 (1994-09-01), Petri
patent: 5422436 (1995-06-01), Zachrai
patent: 5726392 (1998-03-01), Farr et al.
patent: 6093470 (2000-07-01), Petri
Estrada Angel R.
Jarcho Harold G.
Reichard Dean A.
Toupal John E.
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