Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/08—Cable junctions
  • H02G15/18—Cable junctions protected by sleeves, e.g. for communication cable
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/013—Sealing means for cable inlets

Definitions

• the present invention relates to a housing for a conductive entity, to a grommet positioned within such a housing, and to a process for forming the grommet.
• grommets and housings are known in the art for enclosing junctions in conductive entities, including, for example, electrically conductive cables and wires.
• the prior art grommets and housings suffer from the common drawback that they are relatively complicated to design, complicated to install and accordingly, unduly expensive.
• the prior art products have the further drawback that they are not easily adaptable for accommodating a wide range of junction and conductive entity sizes. Accordingly, a craftsman needs to obtain numerous different size grommets.
• grommets useable with such housings are generally not sufficiently effective in keeping water out of the junction being closed.
• Grommets which are typically used for sealing ends of housings are made out of urethane or silicone rubber. These urethane or silicone rubber elastomeric materials provide flexibility in the grommets so that they can be bent around various size conductive entities. Such urethane or silicone rubber elastomeric materials are limited in the amount they can flex around various size conductive entities and are therefore limited in the amount of protection afforded against moisture when sealing around different size conductive entities. Further, these grommets provide protection against moisture by being pushed together tightly to form a tight seal around the conductive entities and between halves of the grommet if there are halves. Therefore, it is required that these grommets are pushed together very tightly in order to provide a good seal against moisture.
• U.S. Patent No. 4,701,574 discloses a grommet which is suitable for use in a conductive entity housing.
• the grommet comprises a gel having an open loop network such that it is elastic and conformable, has a cone- penetration value between 80 and 350 (10 "1 mm) , and an ultimate elongation in excess of 50%.
• the gel comprising the grommet is contained within a member having a plurality of convolutions therearound.
• the grommet further includes passage-forming means through which a conductive entity can be inserted.
• U.S. Patent No. 4,963,698 discloses a preshaped grommet made of a polymeric gel which has a cone penetration value of about 30 to about 400 (10 "1 mm) and an elongation of from about 25% to about 850%.
• Preferred gels comprise a cross-linked non-silicone polymer having an unsaturated olefinic content of less than 10 mole percent and having dispersed therein a liquid in an amount of from about 20% to about 95% by weight based on the weight of the liquid and polymer and from 0 to 0.3 volume fraction of a filler.
• the grommet further includes passage-forming means through which a conductive entity or entities can be inserted.
• 4,839,471 discloses a seal for conductive entity splice closures having two diametrically opposed sealing members which define a cylindrical recess for accommodating a conductive entity.
• the seal is formed from an ethylene-propylene terpolymer with a maximum Shore hardness of 10.
• Each sealing member has a sealing rib extending around and projecting into its recess.
• Each sealing member is also provided with a rib-stiffening element.
• the present invention comprises a housing and a grommet molded-in-place in an end portion of the housing.
• the housing and the mold-in-place grommet together comprise means for accommodating the passage of various size conductive entities and for protecting such conductive entities from atmospheric elements, including water.
• the mold-in-place grommet has passage-forming means for receiving such conductive entities.
• the grommet is formed in place within an end portion of the housing.
• the grommet is formed in place by utilizing a mold.
• the base of the mold is formed by the end portion of the housing.
• the top of the mold is formed by a removable portion that includes a top wall overlying the base portion and side walls extending between the top wall and the base portion.
• the top wall has an opening for receiving a liquid material from which the grommet is formed and reverse features for forming the passage means of the grommet.
• the process of forming in place the grommet comprises the following steps: placing the removable portion of the mold over the base portion of the mold; inserting the liquid material into the mold through the opening; allowing the liquid material to solidify and to conform to the shape of the mold; and removing the removable portion of the mold from the solidified material.
• the mold-in-place grommet is made from a material which is deformable so that the grommet may receive and be shaped around conductive entities of different sizes.
• the material comprising the mold-in-place grommet is also tacky, so that the material will adhere to the interior surface of the housing to secure the grommet in place within the end portion of the housing, to the exterior of a conductive entity which is disposed through the passage-forming means of the mold-in-place grommet, and to itself.
• the mold-in-place grommet comprises two halves, each of which is disposed in a complementary half of the housing.
• the tacky nature of the mold-in-place grommets allows each grommet half to adhere to the other half, forming a protective seal against atmospheric elements, including water.
• the tacky nature of the mold-in-place grommet is also such that the two halves may be pulled away from each other, leaving their former shape intact.
• the mold-in-place grommet is comprised of any material which imparts to it the above properties of deformability and tackiness.
• One such suitable material is an extended elastomeric material comprising a tri- block thermoplastic elastomer polymer and an extender.
• the grommet of the present invention is molded in place within an end portion of a housing and has passage-forming means for receiving a conductive entity.
• the mold-in-place grommet is both deformable and tacky, allowing it to conform to various size conductive entities, and to adhere to the end portion of the housing and to the conductive entity which passes through its passage-forming means.
• the deformability and tackiness also allow the two grommet halves to adhere to each other itself when the housing is forced together, allow the two halves to be pulled apart from each other when the housing needs to be removed from the conductive entity, and allow the two grommet halves to retain their original shape after being pulled apart.
• Figure 1 is an isometric view of the housing with the grommet of the present invention secured therein;
• Figure 2 is an exploded isometric view showing the grommet in greater detail
• Figure 3 is an isometric view showing the interior of the housing with halves of the grommet installed therein, one of the grommets being exploded away from the interior to illustrate the grommet;
• Figure 4 is a close-up view showing the molding of the grommet into the housing.
• FIG. 5 is an isometric view of the grommet of the present invention. Detailed Description of the Invention
• the present invention is directed to a housing for a conductive entity, the housing having an end capable of receiving the conductive entity and a molded-in-place grommet which is positioned in the end of the housing and which has passage means for receiving the conductive entity.
• the present invention is also directed to a grommet for use in protecting a conductive entity which is positioned in a housing having an end portion and an interior surface, the grommet having passage means for receiving the conductive entity and comprising two halves, each of which is molded in place in the end portion of the housing, each half of the grommet comprising a material which itself is capable of adhering to the interior surface of the housing to secure the grommet in place in the end portion of the housing, to the conductive entity, and to itself, the nature of said adherence being effective to form a water-tight seal.
• the two halves of the grommet are brought together to form a passage for receiving the conductive entity or entities.
• the conductive entities will run through the housings and into the passage means of the grommet.
• the grommet is positioned in an end portion of the housing and prevents moisture from entering into the housing.
• the molded-in-place grommet thus acts as a water-tight seal around the conductive entity.
• Both the mold-in-place grommet and the housing comprise two complementary halves; each grommet half is positioned in an end portion of the interior surface of each complementary housing half.
• Each complementary housing half has two end portions, each end portion is capable of having a grommet molded-in-place therein.
• the grommet halves are brought together to form the passage means for receiving the conductive entity by closing the two complementary housing halves.
• the grommet conforms and adheres both to the exterior of the conductive entity and to the interior surface of the housing, thereby providing an effective seal against ingress of moisture from the environment into the interior of the housing.
• the grommet is made up of a material which is both deformable and tacky.
• the deformability and tackiness work in conjunction to impart to the grommet of the present invention many beneficial properties.
• the nature of the deformability allows the grommet to be shaped around conductive entities possessing a wide variety of diameters and also allows the grommet to return to its previous shape after the conductive entity is removed. Accordingly, the same grommet can be used for conductive entities of different size diameters.
• the material is capable of adhering to the end portion of the housing, to the conductive entity and to itself.
• the nature of the adherence is such that no external material is necessary to complete the adhesion.
• the material itself possesses tackiness properties sufficient to allow the material to adhere as described below.
• the material comprising the molded-in-place grommet adheres to the interior surface of the end portion of the housing, thereby securing the grommet in place within the end portion of the housing. Further, when the conductive entity is received within the passage means of the grommet and the two halves of the grommet are brought together to surround the grommet, the material comprising the grommet adheres to the exterior of the conductive entity. However, once the conductive entity is removed from the grommet, it will pull away leaving the grommet in its former shape. Additionally, when the two halves of the grommet are brought together, they will adhere to each other since the material comprising the grommet can adhere to itself.
• the grommet of the present invention is shown in the below-described figures used in a fiber optic housing. However, this grommet can be used in any type of housing which requires that conductive entities enter or exit the housing.
• FIG. 1 shows an isometric view of an aerial fiber optic housing 10.
• the housing is made up of two complementary halves which are hinged together along one side.
• the housing is designed to receive both a through conductive entity 12 which excends from one end of the housing and out the other and a tap conductive entity 14 which extends from only one end of the housing.
• the housing is designed to house splices between the through conductive entity 12 and the tap conductive entity 14.
• the housing could be used to house splices between ends of a through conductive entity 12 wherein additional length on the conductive entity 12 is needed.
• a hanger 16 is also used to secure the housing to a support cable.
• Positioned at both ends of the housing 10 are end portions 18 with openings which allow the conductive entities to pass through to the interior of the housing. In order to prevent moisture from getting inside the housing interior, grommets 20 are secured within these openings.
• the housing is formed by two rigid body halves which are hinged together for movement between an open position and a closed position.
• the two housing halves may be closed together by use of locking devices which are pivotally mounted onto one housing half and latch into a recess formed on the other body half.
• Each rigid body half comprises two end portions 18.
• In each end portion 18 of each body half is positioned half of a mold-in- pace grommet 22.
• the two grommet halves 22 come together to form a whole grommet 20 which acts as a seal to prevent any ingress of moisture from the environment into the housing 10.
• FIG. 2 is an exploded view of the grommet 20 of the present invention which is molded in place within the end portion 18 of the housing 10.
• the grommet 20 is disposed within the end portion 18 of the housing 10 and comprises two halves 22 which fit together when the housing 10 is closed. When the two grommet halves 22 are fit together, they provide a good sealing relationship about the end portion 18 of the housing 10 and also about the conductive entity 12 which extends from the interior of the housing outside. When the housing is in a closed position, the two grommet halves are joined together and form a water-tight seal around the conductive entity and prevent any moisture from entering into the housing.
• Fig. 2 illustrates an embodiment with a conductive entity 12 passing through the housing 10, the conductive entity 12 being sealed by the grommet 20.
• the material comprising the molded-in-place grommet 20 possesses tackiness characteristics. Because of this tackiness, each grommet half 22 adheres to the end portion 18 of the housing 10, to the conductive entity 12 and to the other grommet half 22. The nature of the adherence is such that no external material is necessary to maintain this adhesion.
• the material comprising the grommet 20 also is deformable, so that when the conductive entity 12 is removed from the grommet (which will occur when the housing is moved to the open position) the conductive entity 12 will pull away leaving the grommet in its former shape.
• the grommet can be used again and will again provide a water-tight seal for either the same or a different conductive entity.
• This characteristic of re ⁇ enterability the ability to open the housing and the grommet halves and use the grommet on more than one occasion, is an advantage of the housing and grommets of the present invention.
• FIG 3 shows the interior of one of the complementary halves of the housing 10 and a longitudinal hinge for connecting the two housing halves.
• the hinge is one of many possible methods of connecting the two housing halves.
• the housing half comprises two end portions 18. In one of the illustrated end portions 18 is positioned a grommet half 22 which is molded-in-place. The other end portion 18 has an opening, into which another grommet half 22 will be molded in place.
• FIG. 3 also shows a grommet half 22 exploded out of the housing.
• Each grommet half 22 will be molded directly into place within the end portion 18 positioned on the interior surface of each housing half 10.
• Each grommet half 22 adheres to the end portion 18 of each housing half 10.
• Each of the grommet halves 22 has passage means 24 for receiving a conductive entity 12 extending therethrough.
• the passage means 24 adheres to the exterior of the conductive entity 12 and provides a sealing relationship about such conductive entity 12.
• Each grommet half 22 may also comprise another passage means 26 for receiving the hanger 16 therethrough in order to secure the housing 10 to a support cable.
• the grommet illustrated in Fig. 3 may also comprise additional passage means, 28 and 30, which are capable of receiving tap conductive entities 14 if it is necessary for such a tap conductive entity 14 to be extended into the housing 10 from that end of the housing. Because these passage means 28,30 will not always receive a cable, the passage means may be designed with integral plugs 32,34. These integral plugs 32,34 block off one end of the additional passage means 28,30. Further, they extend upwardly from the passage means in a semicircular form.
• the plugs 32,34 when the two halves 22 of the grommet 20 are brought together, the plugs 32,34 will be received within the passage means 28,30 on the complementary half 22 of the grommet 20, thereby plugging up the additional passage means 28,30 and preventing moisture from being received into the interior of the housing 10 through the unused channels 28,30, see Fig. 2.
• the plugs 32,34 will be compressed or deformed into the passage means and form a water-tight seal around the conductive entity.
• FIG. 4 shows a mold 40 for molding the grommet half 22 into place within the end portion 18 of the housing and Fig. 5 shows an exploded view of the grommet half 22 which will be molded-in-place.
• a mold is placed over the end portion 18 of the housing 10 and then a liquid material is poured into the mold. Once the liquid hardens, the mold is removed, leaving a grommet half 22 molded-in-place within the end portion 18 of the housing 10.
• the end portion 18 of the housing 10 acts as the base of the mold.
• the top portion of the mold 40 is a removable portion comprising a top wall and side walls.
• the top wall overlies the base portion and the side walls extend between the top wall and the base portion.
• the top wall has an opening (or openings) 42 for receiving a liquid material from which the grommet half 22 is formed.
• the top wall also has reverse features for forming passage means 24, 26, 28, 30 of the grommet half 22. When the liquid from which the grommet half is formed hardens against the top wall of the mold, the top of the grommet half 22 will have the shape as depicted in Fig. 5, with all the necessary passage means 24, 26, 28, 30 and plugs 32, 34 for receiving conductive entities.
• the removable portion of the mold 40 is placed over the end portion 18 of the housing 10.
• Side walls may either be an integral part of the removable portion of the mold, or they may be separate individual pieces. If they are separate from the removable top portion, then they are inserted along both sides of the mold between the top wall and the base portion. The side walls keep the liquid material within the mold cavity and form the sides of the grommet half 22. If the side walls are integral to the top wall of the removable portion of the mold, then they extend downwardly from the top wall.
• the removable portion of the mold is first placed over the end portion 18 of the housing 10.
• a liquid material is then inserted through the opening 42 of the top wall of the removable portion of the mold and into the interior cavity of the mold.
• the cavity is defined by the base portion, the two side walls, and the top wall.
• the nature of the liquid which is inserted into the cavity of the mold is such that it hardens and conforms to the shape of the interior cavity of the mold.
• the removable portion of the mold 40 is removed, resulting in a grommet half 22 molded-in-place within the end portion 18 of the housing 10.
• Fig. 3 shows in detail an end portion 18 wherein a grommet half 22 may be molded-in-place.
• the end portion 18 of the housing has ribs 50 and undercuts 52 which help in keeping the molded-in-place grommet locked within the end portion 18.
• the ribs 50 extend from the interior surface of the housing to the hinge side of the housing.
• the ribs 50 are undercuts 52 or reverse draft features which allow the molten elastomeric material to flow under and into the undercuts 52.
• the combination of the ribs 50 and the undercuts 52 keep the grommet locked into place within the end portion 18.
• the mold-in-place grommet of the present invention may be made from any material which possesses sufficient tackiness and deformability to impart to the grommet the attendant beneficial properties described herein.
• a preferred material for forming the mold-in-place grommet is an extended elastomeric material which comprises a tri-block thermoplastic elastomer and an extender.
• the tri-block thermoplastic elastomer may comprise a primary tri-block thermoplastic elastomer (hereafter "primary elastomer”) and a secondary tri-block thermoplastic elastomer (hereafter "secondary elastomer”) .
• the primary elastomer has a higher melt viscosity than the secondary elastomer.
• a compound with a lower melt viscosity (the secondary polymer herein) is less viscous, and therefore is more readily able to flow.
• the secondary elastomer imparts to the material from which the grommet is formed the ability to flow more readily at the temperature at which the grommet is molded in place.
• the addition of such a secondary polymer enables the liquid material which is inserted into the mold to more readily flow into the cavities which define the shape of the mold.
• Alternative embodiments of the grommet of the present invention are made from materials which comprise either a primary elastomer alone or a combination of a primary and a secondary elastomer.
• the preferred primary and secondary polymers in accordance with the present invention may have a relatively wide range of melt viscosities depending upon the particular application requirements, it is generally preferred that the primary elastomers in accordance with the present invention have a melt viscosity of greater than about 25,000 cps, more preferably greater than about 40,000 cps. Unless otherwise indicated herein, melt viscosity refers to the viscosity of the elastomer when present at a concentration of 5% in Kaydol oil at 300°F (150°C) .
• the secondary elastomers of the present invention preferably have a melt viscosity of less than about 20,000 cps, and even more preferably less than about 15,000 cps.
• KRATON G1651 is a poly(styrene-ethylene-butylene- styrene) tri-block copolymer, available from the Shell Development Corporation, having a styrene end block to ethylene and butylene center block ratio of about 33:67. As described in the Shell Company Technical Bulletin SC1102-89, KRATON G1651 has a melt viscosity of 42,700 cps when present at a concentration of 5% in Kaydol oil at 300°F. KRATON G1651 is thus a primary elastomer as defined herein.
• KRATON G1654 is a triblock copolymer, poly(styrene-ethylene-butylene-styrene) , sold by Shell Development Corporation as a low molecular weight analog of KRATON 1651X. KRATON 1654 has been tested and found to have a melt viscosity of about 14,200 cps. Accordingly, KRATON G1654 is a secondary elastomer as defined herein.
• Tri-block thermoplastic elastomers as described herein can be prepared according to a number of well- known techniques, including the methods described in U.S. Patent No. 3,485,787 which is incorporated herein by reference.
• Other suitable tri-block copolymers include those disclosed in U.S. Patent No. 5,360,350 which is incorporated herein by reference.
• the material comprising the molded-in-place grommet may also comprise an extender which acts as a plasticizer to soften the tri-block thermoplastic elastomer.
• the extender of the present invention may comprise a primary extender and a secondary extender. When the polymer to extender attraction is strong, the extender has high compatibility with and high solvency for the thermoplastic elastomer, and is a secondary extender. Where the polymer-to-extender attraction is relatively weak, the extender is of the primary type. Suitable extenders include a Kaydol mineral oil (primary extender) or Panalane H300E (secondary extender) .
• a material suitable for forming the molded-in-place grommet comprises a tri-block thermoplastic elastomer and an extender.
• the relative proportions of the polymer and the extender are preferably selected to provide the grommet composition with the deformability and tackiness characteristics described herein.
• the present grommet compositions preferably comprise a minor proportion by weight of tri-block thermoplastic elastomer and a major proportion by weight of extender for the elastomer.
• the grommet comprises an elastomeric material including about 2 to about 12% by weight of a primary elastomer and about 70 to about 95% by weight of a primary extender.
• the grommet comprises an elastomeric material including about 2 to about 13% by weight of a primary elastomer and about 0 to about 10% by weight of a secondary elastomer.
• a preferred embodiment may also comprise an elastomeric material which includes about 70 to about 95% by weight of a primary extender and about 0 to about 25% by weight of a secondary extender.
• the grommet comprises an elastomeric material having about 5% by weight of a primary elastomer and about 2.5% by weight of a secondary elastomer.
• the extended elastomeric material further comprises about 91.4% by weight of a primary extender.
• the extended elastomeric material from which the mold-in-place grommet is formed is typically made by mixing a tri-block thermoplastic elastomer with an extender. Suitable tri-block thermoplastic elastomers that can be used are KRATON G1651 and KRATON G1654.
• the extender can be a Kaydol mineral oil or Panalane H300E extender.
• ingredients can be included into the material to provide various properties such as anti- oxidants, fungicides or colorants.
• a few typical additives are Irganoz 1010, Tinuvin 234, and Tinuvin T770 which are all anti-oxidants, Metasol TK100, a fungicide, and Regal 400R carbon black, a colorant.
• Other possible polymers, extenders and various other ingredients that could be used are described in U.S. Patent No. 5,360,350 which is incorporated herein by reference.
• the material from which the mold-in-place grommet is formed is made out of 5% by weight of KRATON G1651, a tri-block primary elastomer; 2.5 % by weight KRATON G1654, a tri-block secondary elastomer; 91.4 % by weight Kaydol mineral oil, a primary extender; 0.5 % by weight Irganox 1010; 0.2 % by weight Tinuvin 234; 0.2 % by weight Tinuvin T770; 0.05 % by weight Metasol TK100; and 0.15 % by weight Regal 400R.
• the grommet is prepared by weighing the proper amount of the Kaydol mineral oil extender into a mixer tank.
• the additives such as the anti-oxidants and fungicides are added to the extender in the tank.
• the KRATON G1651 and G1654 are then added to the tank.
• the mixture is mixed at a slow sweep speed and low disperser blade speed.
• the tank and the material inside are then placed under a vacuum atmosphere and heated to 320°F for a total mix time of about 2 to about 3 hours.
• carbon black which has been pre- wetted with Kaydol mineral oil is added to the tank and the mixture is stirred for an additional 30 minutes.
• the grommet is formed in place within the housing by using a mold which is secured against the housing.
• the extended elastomeric compound is heated to a temperature of 380°F and used to fill the mold against the cavity.
• the grommet is allowed to cool for 15 minutes and the mold is then removed leaving a completed molded-in-place grommet.
• the grommet formed in this example has a cone penetration value of 195 (10 "1 mm, measured at 25°C) , a slump resistance of 0 inches (measured at 80°C for 24 hours) , a Brookfield viscosity of one million cps (measured at 150°C/300°F) , a tear strength of 7.5 lb. /in, and an elongation of greater than 1950%.
• Suitable parameters for preferred embodiments of the material from which the grommet is formed are as follows: cone penetration value ranging from about 150 to about 225 10 "1 mm; tear strength greater than about 5 lb/in.; and elongation greater than about 1000%.
• Cone penetration value is measured by ASTM D217, which is a standard test procedure entitled "Standard Test Methods for Cone Penetration of Lubricating Grease,” adopted by the American Society for Testing and Materials (ASTM) and used throughout the materials industry to determine viscosity of lubricating greases. Slump resistance is measured by a modified version of ASTM Test method D2202. These tests are disclosed in U.S. Patent No. 5,360,350, which is incorporated herein by reference.
• the grommet can accommodate various sizes of conductive entities extending therethrough and provide effective sealing against moisture. Further, the grommet can be molded in place within the housing, thus becoming an integral part of the housing.
• the housing and the mold- in-place grommet of the present invention and many of their attendant advantages will be understood from the foregoing description. It is apparent that various charges may be made in the form, construction, and arrangement of parts thereof without departing from the spirit or scope of the invention, and without sacrificing all of its material advantages.

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• Connector Housings Or Holding Contact Members (AREA)
• Insulating Bodies (AREA)
• Installation Of Indoor Wiring (AREA)

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• 1997
  • 1997-05-22 WO PCT/US1997/008647 patent/WO1997044876A1/en not_active Application Discontinuation
  • 1997-05-22 EP EP97927688A patent/EP0900463A1/de not_active Withdrawn
  • 1997-05-22 JP JP09542703A patent/JP2000515358A/ja active Pending

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