BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be clearly understood by reference to the attached drawings in which:
FIG. 1 is a front plan view of a first embodiment of the grommet;
FIG. 2 is a cross section view of the first embodiment depicted in FIG. 1;
FIG. 3 is a front plan view of the first embodiment of the grommet shown mounted in a fiber optic enclosure device;
FIG. 4 is a side plan view of a second embodiment of the grommet according to the disclosure;
FIG. 5 is a side plan view of a third embodiment of the grommet according to the disclosure;
FIG. 6 is a front plan view of the first embodiment of the grommet with a cable passing therethrough;
FIG. 7 is a front plan view of a fourth embodiment of the grommet;
FIG. 8 is a front plan view of a fifth embodiment of the grommet; and,
FIG. 9 is a cross section view of the fifth embodiment depicted in FIG. 8.
DETAILED DESCRIPTION
Referring to FIGS. 1-3, wherein a first embodiment of a grommet 10 is depicted comprising an outer peripheral section or outer ring 12 and a central section or inner ring 14. The outer peripheral section 12 includes an outer circumferential surface 13 for sealing the grommet 10, for example, within an opening defined between an end plate 15 and a bulkhead 17 of a fiber optic enclosure. Outer ring 12 can include a continuous circumferential and axially extending sealing surface 13, as shown in FIG. 1. Sealing surface 13 can be made of the same harder or more rigid material as the harder portion of grommet 10. This feature provides for better wear of the grommet 10 in normal use as the harder sealing surface 13 will be more resistant to abrasion caused by frictional contact with the engaging surfaces of, for example, the end plate 15 and bulkhead 17 of the fiber optic enclosure. Grommet 10 may be formed from any known flexible grommet material such as the homogenous, flexible rubber-like materials presently used in the art. The outer peripheral section 12 can be generally the same thickness as the inner ring 14. The inner ring 14, in one version, defines a central opening, section, or passageway 16. The inner ring 14, in another version, can include piercable membrane selectively closing the inner ring 14 and sealing its central opening (not shown).
FIG. 3 shows the grommet 10, including the central opening 16 forming an opening or passageway for insertion of a member 20, i.e. cable or wire, to be held in the grommet. An interior surface 22 of the inner ring 14 provides for frictional and sealing engagement with member 20. In the installed position, grommet 10 provides a resistant force to member 20 in axial and radial directions as indicated by arrows 30 and 32, and a relatively less resistant force in universal tilting directions as indicated by arrows 34 and 36. It is to be appreciated, once the grommet 10 is installed, the member 20, including a fiber optic wire 21 therein, will be securely retained and resistant to axial and radial movements while allowing universal tilting to provide for certain variability in mounting angles. The inner ring 14 can maintain sealing engagement of the wire 20 whether in a tilted orientation or aligned orientation relative to an axis 38 through the central opening 16.
Flexibility of the inner ring 14, and the associated interior surface 22 of the grommet, can be invaluable in situations where it is difficult or impossible to align member 20 at an angle perpendicular to the bulkhead member 17. Likewise, the opening 16 permits axial movement of member 20 to aid in initial positioning during installation of the grommet. This axial movement can be to a considerable extent. After installation the ease of axial and radial movement is significantly reduced.
As shown in FIGS. 2 and 3, one embodiment of the present disclosure provides that the softer material of the inner ring 14 extends axially into interior portion of a relatively harder outer ring 12. In this manner, first and second shoulders 48, 50 are presented into an interior cutout 52 of outer ring 12. Cutout 52 is an example of a profile. Other profiles are contemplated, i.e. rounded edges, serrated edges, etc. This provides rigidity to the inner and outer rings 14, 12. In addition, the inner ring 14 resists decoupling from, and shearing away from, the outer ring 12 when the member 20 is moved axially in direction 30 and/or radially in direction 32 (refer to FIG. 3).
While grommet 10 is shown as being cylindrical or circular to be inserted in a circular hole or aperture, it will be appreciated that other configurations of the sealing perimeter such as a rectangular shape can be accommodated.
In an alternative configuration, the grommet can include a slit extending from the outside surface to the opening (not shown), wherein one or more wires may be dropped into the grommet in a generally radial direction. However, it will be understood by those skilled in the art that any of the embodiments of the present invention may be adapted such that the wires may be dropped into the grommet rather than inserted through one or more apertures in the central portion or section of the grommet.
The outer ring and the relatively softer sealing inner ring materials can be thermoplastic or thermosetting resins or mixtures thereof which can be cast as plastisols such as vinyl. The outer ring portion can be an annular ring and the central hole filling portion can be a softer vinyl body portion which can include a flexible snout 19 (see FIG. 2) having a central opening to support the wire or cable member which extends through the opening. This snout 19 can provide enough flexibility to yield or stretch and sealingly engage the member 20 and further inhibit axial and radial movements of the inserted member relative to the grommet after installation.
Referring now to FIGS. 4 and 5, wherein other embodiments of a grommet 110a, 110b are therein shown. It is to be appreciated that an outer sealing surface can include a bulbous flange 113a (FIG. 4), or multiple bulbous flanges 113b (FIG. 5). The flanges 113a, 113b assist with sealing the opening of the fiber optic enclosure. In particular, flanges 113a, 113b assist with sealing an uneven, rough, or less than round opening in a two piece fiber optic enclosure.
Grommet 10 can have a harder or more rigid portion in the form of outer ring 12. The largest dimension or diameter of the outer ring can be larger than the aperture 42 into which the grommet 10 is inserted thereby transmitting axial forces inward around the entire grommet after installation. Referring now to FIG. 6 wherein it is to be appreciated that in a mounted position, tightening the end plate around the outer ring results in compressive forces 60 being transmitted radially to the inner ring 14. The inner ring 14 in turn communicates compressive forces 62 around member 20. Counter axial forces 64, resulting from insertion of member 20, extend from the inner surface of the inner ring 14 outward. The relatively soft materials in the inner and outer rings 14, 12 enable the opposing forces to be dissipated and equalized within the rings while providing retention forces on member 20 and sealing of the outer surface 13 of the outer ring 12 within, for example, the end plate 15 and bulkhead 17. The aforementioned properties provides for a self-adjusting and self-sealing grommet 10 designed to adjust to different sized cables and wires passing therethrough, and to adjust for different sized openings mounted therein. Once installed, the resilient and ‘spring-like’ inner and outer rings 14, 12 not only retain the grommet firmly in place but also provide for a dust and water resistant seal around the outer surface of the grommet and around the cable passing through the inner opening.
The inner and outer rings can have substantially the same thickness 70 to facilitate retention of member 20 and to facilitate dust and water resistance. The ratio of thickness 70 of grommet 10 to the inside diameter 72 of the inner ring 14 can be in the range of at least two to one. One particular application includes a ratio of at least four to one. The relatively soft material of the inner ring, along with the thickness of the inner ring, provides frictional gripping forces to hold and seal a member therein after installation of the grommet in an enclosure device. The relatively large surface area of the cable in contact with the interior surface of the inner ring can be calculated as: [pi×(diameter 72)×(thickness 70)]. It is to be appreciated that the resiliency of the inner ring enables a wide range of cable sizes to pass through the passageway. In one application, a diameter 72 of 0.250 inches was used to accommodate and seal around a member 20 ranging in diameter between 0.125 inches and 0.500 inches. Similar ratios can be achieved for various sized members (regular and irregular) and associated diameters, for example, members ranging in diameter from one fourth to two times the diameter of the opening 16. After installation, member 20 can be universally tilted (not shown) without disturbing its dust and water resistance. Grommet 10 thereby allows and accommodates minimum bending radii of fiber optic cables, while at the same time resisting axial and radial movements of same said fiber optic cables resulting from the frictional forces between the surface area of the cable and the interior surface of the inner ring.
The combination of the inner ring and outer ring, along with their relative hardnesses, enables mounting in a range of openings in the engaging surface, as well as a range of fiber optic cables to be mounted through the center of the inner ring. In this manner, a limited number of the grommets can be carried by the field technician and each grommet used as a ‘universal’ grommet for a multitude of installations having varying dimensional requirements. The present disclosure provides an improved grommet having a central section which will conform to and seal around one or more wires, having varying diameters, which pass through the grommet. Referring to FIG. 7, there is illustrated another embodiment of a grommet 210 including multiple openings 216a, 216b, 216c, 216d, within an inner ring 214. Any number of openings can be arranged within inner ring 214. It is to be appreciated that a relatively harder outer ring 212 surrounds inner ring 214.
Referring now to FIGS. 8 and 9 wherein still another embodiment of a grommet 310 is therein shown. It is to be appreciated that a two stage injection molding process or method of manufacturing the grommet 310 can be employed. At the first injection molding station the harder or more rigid material portion, i.e. outer ring 312, of the grommet can be injection molded. The harder molded material H, along with one of the mold halves, can then be transferred to a second injection molding station where the softer material S can be injection molded to bond with the harder material H. The softer material S includes all of the inner ring 314 components. When the second injection molding step is complete, the grommet is ejected from the mold and the transferred mold half can be returned from second molding station to first molding station to repeat the process.
Alternatively, rings 312, 314 may be thermally bonded or otherwise joined by commingling of cavities. For example, such mating engagement may be provided by fabricating the grommet in a dual durometer molding process using a rigid material to form configuration 312 and a less rigid material to form configuration 314. If desired, such mating may be provided by a male segment and female segment of a typical T-shaped connection. The outer portion 312 may be a rigid or semi-rigid material such as any of a variety of thermoplastic and thermoset resins and the central portion 314 may be a soft and flexible gum-my material such as a thermoplastic elastomer.
As mentioned earlier, a variety of thermoplastic or thermosetting resilient plastics can be used for the harder and softer materials. In order to facilitate the sealing engagement in installation and retention, the harder material H, for the outer ring 12, 112, 212, 312 can have a durometer hardness in the range of 30 to 70 Shore A. The specific hardness of the outer ring is dependent upon the specifications of the grommet. Durometer hardnesses between 40 Shore A and 60 Shore A for the outer ring element have been used for different applications. The relatively softer material, for the inner ring 14, 114, 214, 314 can have a durometer hardness in the range of 5 to 40 Shore A. The specific hardness of the inner ring is dependent upon the specifications of the grommet. Durometer hardnesses between 10 Shore A and 30 Shore A for the inner ring element have been used for different applications. The ratio of hardness of the outer ring to the inner ring can be in the range of 1.2 to 1.0 and 14.0 to 1.0, respectively.
Additionally, the outer diameters of the inner and outer rings affect the resiliency of the grommet and the sealing of an opening, i.e. opening 316. In one example, the outer diameter of the inner ring can be at least one half the outer diameter of the outer ring (see for example FIG. 6). In another example, the outer diameter 320 of the inner ring 314 can be at least three fourths the outer diameter 322 of the outer ring 312 (FIG. 8). The latter example results in a relatively slower recovery of the grommet back to its original shape after compression, while providing for increased sealability of the central opening(s). This accommodates a variety of cables and can ensure that there is a tight seal even where the cable itself has imperfections on the surface. It is to be appreciated that the latter example includes a larger volume of a relatively softer material relative to the total volume of the grommet.
A thermoplastic polypropylene resin can be formulated for both the harder and softer components of the grommet. It is to be appreciated that the material for the inner and outer rings can be selected from other materials including, for example, polypropylene, rubber, urethane, and silicone. Fiberglass may be added to enhance the strength and rigidity of the material. Mica may be added to enhance rigidity to a greater extent but would have the added effect of reducing tensile and shear strength.
From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present invention which come within the province of those persons having ordinary skill in the art to which the aforementioned invention pertains. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the appended claims.
Patent Application
20080066949
