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
  • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
  • H02G3/02—Details
  • H02G3/06—Joints for connecting lengths of protective tubing or channels, to each other or to casings, e.g. to distribution boxes; Ensuring electrical continuity in the joint
  • H02G3/0616—Joints for connecting tubing to casing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/16—Sealings between relatively-moving surfaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16J—PISTONS; CYLINDERS; SEALINGS
  • F16J15/00—Sealings
  • F16J15/16—Sealings between relatively-moving surfaces
  • F16J15/164—Sealings between relatively-moving surfaces the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid
• • 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
  • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
  • H02G3/02—Details
  • H02G3/06—Joints for connecting lengths of protective tubing or channels, to each other or to casings, e.g. to distribution boxes; Ensuring electrical continuity in the joint

Definitions

• the present invention relates to the field of sealing systems and methods of forming seals.
• the invention provides a seal system that is resistant to leakage due to low temperatures, as well as a method of using such sealing systems and methods of their manufacture.
• Gaskets and other sealing members are used in a broad array of applications to prevent encroachment of material beyond two adjoining surfaces. Such gaskets are normally placed between the two surfaces and the two surfaces are brought together, compressing the gasket between the two surfaces. Accordingly, fluids, gases and other materials are prevented from flowing between the two surfaces.
• Such gaskets have been made from many different materials ranging from cork to exotic elastomers. Representative gaskets are described in U.S. Patent Nos. 3,524,794, 4,196,162, 4,317,575, and 2,806,509.
• Fig. 1 illustrates the volume change (in %, from 20°C) as a function of temperature for various elastomers. As seen, the volume change is significant, and this can hurt gasket performance at low temperatures.
• the data therein are taken from Robbins et al. , Adv. Crvo ⁇ . En ⁇ . (1963) pgs. 287-299.
• the sealing system provides for the use of a body defining a cavity.
• the cavity is filled or substantially filled with a material having a lower coefficient of thermal expansion than the body or materials that expand at low temperatures (e.g. water) .
• low coefficient of thermal expansion includes materials that may expand over at least a portion of a low temperature range of interest. In most cases herein the temperature range of interest will be below ambient such as below about 4°C, and often in the range of 20°C to -40 ⁇ C.
• the body may shrink or attempt to shrink considerably due to its large coefficient of thermal expansion, but the compressive force applied between two sealed surfaces will not decrease appreciably due to the internal, low coefficient of thermal expansion filler.
• the low coefficient of thermal expansion filler prevents excessive contraction of the seal. Accordingly, the risk of failure at low temperature is substantially reduced.
• the seals according to the present invention are easily installed, and highly conformable.
• the seals require. little compression to seal, and have minimal change in dimensions as temperature is changed.
• the seals may be resistant to chemical and environmental attack, through appropriate selection of the body material while also being easily reusable.
• the filler material may be selected from a wide range of materials that may or may not be resistant to environmental attack.
• Fig. 1 is an illustration of the coefficient of thermal expansion of various materials
• Figs. 2a to 2c illustrate the manufacture of one embodiment of a gasket herein;
• Figs. 3a to 3c illustrate compressive force as a function of temperature
• Fig. 4 illustrates a cable enclosure assembly
• Figs. 5, 6, and 7 illustrate compressive force for water based seals
• Figs. 8a, 8b, and 8e illustrate an alternative embodiment of the seal
• Figs. 9a, 9b, 9c, and 9d illustrate a cable enclosure, along with various seals therefore;
• Figs. 10a and 10b illustrate an in-line cable enclosure
• Figs. 11a and lib illustrate a butt splice enclosure
• Figs. 12a, 12b, 13a, and 13b illustrate seals with soft rings
• Figs. 14a and 14b illustrate seals with compression rings
• Figs 15a to 15c illustrate a dual seal system
• Figs. 16a to 16d illustrate another version of a dual seal system
• Figs. 17a to 17c illustrate another version of a dual seal system
• Figs. 18a to 18c illustrate another version of a dual seal system
• Figs. 19a to 19d illustrate another version of a dual seal system.
• Example B Example B.
• Figs. 2a to 2c illustrate one embodiment of the invention, along with a method of making such embodiments.
• the invention provides for the use of a body 2.
• the body defines an internal space 4.
• the body is cylindrical in shape, although the shape of the body will vary dramatically from application to application depending upon the shape of the surfaces to be sealed.
• the body is preferably an elastomeric material, i.e., a material that at least partially recovers its original shape when compressed or stretched.
• the body is initially open on its top surface.
• the entire top surface may be fully open as shown in Fig. 2, or one or more small apertures may be provided in the body.
• the opening(s) in the top of the body are used to place a fill material 6 in the body as shown in Fig. 2b.
• the internal space 4 is substantially filled with the fill material such that the fill material is closely packed therein.
• substantially filled is intended to mean filling of more than 30% of the volume of the internal space with the fill material, preferably more than 50% of the internal space, more preferably more than 70% of the internal space, preferably more than 90% of the internal space, preferably more than 95% of the internal space, and most preferably more than 99% of the volume of the internal space.
• the body and the fill material have different coefficients of thermal expansion, the fill material preferably having a lower coefficient of thermal expansion than the body.
• lower it is intended to mean herein not only materials that have lower coefficients of normal expansion, but also those that expand as temperature is decreased.
• the coefficient of thermal expansion of the fill material is less than 200, preferably less than 150, preferably less than 100, preferably less than 60, preferably less than 10, and most preferably less than 5xl0 "6 m/m/°C.
• the coefficient of thermal expansion of the fill material is more than 10% less than that of the body, preferably more than 50% less than the body, and most preferably more than 100% less than that of the body material.
• the fill and the body materials desirably selected such that the overall structure of the seal is both compliant and resilient.
• Preferred materials for the body are thermoset elastomers such as natural rubber, styrene-butadiene rubbers, butyl rubber, ethylene- propylene rubbers, polyisoprene, polybutadiene , nitrile elastomers, neoprene, polysulfide polymers, polyacrylic rubber, silicone rubbers, chlorosulfonated polyethylene, fluorocarbon elastomers, fluorosilicones, polyurethane elastomers, styrene-butadiene copolymers, epichlorohydrin polymers, phosphonitrilic fluoreleastomer, tetrafluoroethylene-propylene copolymers, ethylene-methyl acrylate copolymer, or perfluoro elastomers, as well as mixtures thereof.
• the body is made of thermoplastic elastomers such as styrene-diene-styrene triblock copolymers (SBS, SIS, SEBS, SEPS), thermoplastic polyurethanes (TPU) , thermoplastic olefins (TPO) , elastomers/thermoplastics alloys (e.g., acrylonitrile- butadiene rubber/pvc alloy), as well as mixtures thereof.
• the body is RTV silicone rubber such as Silasic J available from Dow Corning or thermoplastic elastomers such as Kraton rubber.
• all or part of the body is lined with a water resistant barrier such as metal foil.
• a water resistant barrier such as metal foil.
• Such barriers may cover only a portion of the gasket such as a ring on the top of the gasket, or may line the entire inner surface of the body.
• Preferred materials for the fill material include glasses, especially with a low (e.g., less than about 200xlO "6o C "1 ) coefficient of thermal expansion such as sodium borosilicate, lime magnesia aluminosilicate, 96% silica, and similar glasses; graphite or carbon pellets; ceramics; filled and unfilled thermoset and thermoplastic materials epoxys with a low (e.g., less than lOOxlO' ⁇ C" 1 ) coefficients of thermal expansion; metal spheres having a low coefficient of thermal expansion, glasses, ceramics, metal and metal alloys, graphite, carbon, mica, other mineral and synthetic fillers, filled and unfilled thermoset and thermoplastic materials, and the like, as well as mixtures thereof.
• the coefficient of thermal expansion of various representative materials that may be used in conjunction with the invention herein are illustrated in Table 1.
• fill materials with low coefficients of thermal expansion are hard; accordingly solid blocks of such materials are often not desirable since the compliancy of the seal will be compromised.
• compliancy of the seal is maintained by using finely divided particles of such fill materials without interspersed rubber or other body materials.
• such non-compliant fill materials are provided with particle sizes of preferably less than about 1000 microns, preferably less than 500 microns, and preferably less than 300 microns.
• the fill material is glass microspheres having a diameter of between about 150 and 250 microns. Such spheres are available from Potters Industries Inc. under the name Spheriglass.
• the particles of fill material preferably maintain greater compliancy by leaving the interstices between the particles devoid of elastomer such as the elastomer of the -body. Accordingly, the particles of fill move about freely in the body, allowing the structure to be compliant.
• the particles or spheres are substantially solid, i.e., each of the spheres is made of a substantially solid material such as glass. Hollow particles may be used to reduce weight.
• the void between particles of fill material is not filled. Accordingly, preferably only about 50% of the volume of the body is filled with fill material, preferably more than 75%, and more preferably more than 90% of filled volume will be highly dependent on particle size selection.
• the opening(s) in the body are sealed as shown in Fig. 2c.
• the body is sealed ab initio, and the fill is injected with, for example, an injection needle, optionally with another needle for pressure venting.
• the resulting body and internal fill material are formed in the shape necessary to mate with adjoining surfaces that are to be sealed.
• Gaskets made according to the invention will have a variety of uses, including conventional uses such as pipe gaskets and the like.
• the gaskets are used as seals for CATV, telephone and power cable connectors, closures for free- breathing aerial applications (i.e., Raychem's TRAC ⁇ line of products, fiber optic splice closures, cable TV splice cases, pressurized and unpressurized copper cable closures, pedestal closure system, enclosures for preconnectorized cables, and terminal boxes.
• closures for free- breathing aerial applications i.e., Raychem's TRAC ⁇ line of products
• fiber optic splice closures i.e., fiber optic splice closures, cable TV splice cases, pressurized and unpressurized copper cable closures, pedestal closure system, enclosures for preconnectorized cables, and terminal boxes.
• a gasket in which a thermocouple was embedded was placed in a cylindrical stainless steel holder having approximately the same OD as the gasket.
• the assembly was placed between the arms of an Instron which were enclosed within an insulated chamber conditioned to a predetermined temperature and the gasket compressed with a given force (e.g., 100 lbs). The change in compressive force as the sample was cooled or heated from room temperature was measured and recorded.
• the silicone rubber gasket was made from Silastic J available from Dow Corning.
• the body of the comparison gasket was made of the same material.
• the internal space in the comparison gasket was filled with glass microspheres having an average diameter of 219 microns and available from Potters Industries.
• Figs. 3a and 3b compare the performance of the silicone rubber gasket and the gasket according to the present invention. Specifically, Figs. 3a and 3b plot the compressive force for each of the gaskets as a function of temperature. Fig. 3a illustrates the results for gaskets with a tight fit (i.e., a gasket in which the outside diameter of the gasket was the same as the inside diameter of the cylinder) . Fig. 3b illustrates the results for gaskets with a loose fit (i.e., a gasket in which the outside diameter of the gasket was 1.25" while the inside diameter of the cylinder was 1.351").
• a tight fit i.e., a gasket in which the outside diameter of the gasket was the same as the inside diameter of the cylinder
• Fig. 3b illustrates the results for gaskets with a loose fit (i.e., a gasket in which the outside diameter of the gasket was 1.25" while the inside diameter of the cylinder was
• the silicone rubber gasket at room temperature has approximately the same compressive force as the gasket according to the present invention.
• the compressive force exerted by the silicone rubber gasket drops much more quickly than the gasket according to the present invention.
• the solid rubber gasket drops well below this value at about 15°C, while the -gasket according to the present invention did not reach the critical value at the lowest tested temperature of -40°C. While the loose fitting silicone rubber gasket did not drop below the critical value, its compressive force was substantially lower than that of the present invention.
• Fig. 3c illustrates the radial deflection of a gasket as a function of compressive force applied to the gasket for both solid Silastic "J" gaskets (i.e., silicone rubber) and gaskets as described above.
• the gaskets according to the present invention deflect radially much more easily as pressure is applied.
• the results shown therein are for a gasket of 1.25" diameter and 1" height.
• the ability to deflect with low applied force is one of the key differences between the seals herein and solid rubber seals. This allows the seals to conform around irregular shapes (confor ability) , to seal cables of a wide range of diameters (cable range taking ability) and allows the manufacture of large size seals. Because of the high modulus of solid rubber seals, conformability, range taking ability and seal size are limited. Furthermore, the force required to effect sealing is much lower for the seals therein than for solid rubber seals.
• gasket structures were applied to an aluminum test fixture as illustrated in Fig. 4. As shown therein, a tubular body 8 was sealed at one end with a gasket 10 against a washer 12 and a cap 14. The gasket 10 sealed around a cable 16 that extended into the body 8. The other end of the device was sealed with a cap having a pressurization source/valve 18. The device was initially pressurized to 5 psi and the temperature was repeatedly cycled from -40°C to 60°C.
• Tables 2a and 2b illustrate the results of the thermal cycling experiment. By contrast, solid silastic J gaskets failed after 12 and 23 cycles.
• the fill material expands at low temperatures such as below 4°C.
• the body is formed in a manner similar to that of the above embodiment. Hollow, cylindrical containers are molded using, in the case of a silicone rubber, material such as Dow Corning Silastic J. The body is then filled with materials that expand at low temperatures such as hydrogels or water-swellable polymers. If necessary, the consistency of the gel is adjusted, and the top of the container is sealed by addition of silicone rubber mix on the top of the container.
• the body is compression molded of, for example, Kraton rubber. The body is filled with water, hydrogels, or water swellable polymers.
• the top of the container is closed by bonding disks cut from a slab of the same rubber material as the rest of the body with a toluene solution containing the rubber.
• the structure is formed in a closed manner and the fill is added with a syringe or similar instrument.
• the fill material is preferably selected from water or aqueous solutions, water absorbent materials, water swellable polymers, natural, or synthetic hydrogels.
• Water solutions or dispersions preferably contain organic or inorganic compounds used as stabilizers, fungicides, thickeners, or the like.
• Natural hydrogels are preferably contain materials selected from the group of gelatin, gum tragacanth, locust bean gum, guar gum, sodium alginate, gelatinous polysaccharides, and the like, as well as mixtures thereof.
• such fill materials are preferably based on polyethylene oxide, polyacrylic and poly ethacrylic acids, polyacrylic and polymethacrylic esters, polyhydroxyalkyl metacrylates or acrylates, polyacrylamide or polymetarylamide, poly- n-isopropylacrylamide, poly-n-vinyl-l-2-pyrrolidinone, crosslinked polyvinyl alcohol, polyvinyl propanol, polyethylene oxide, carboxymethyl or hydroxyethyl cellulose, hydroxypropyl methylcellulose, crosslinked polypropenoic acid, polyelectrolyte complexes, charged polymers carrying ionizable groups, and mixtures thereof.
• Tubular gaskets similar to those described above were formed from silicone rubber with their cores filled with gelatine gel (3.5% gelatine and 96.5% water).
• the structures were applied to an aluminum test fixture as illustrated in Fig. 4. The device was initially pressurized to 5 psi and the temperature was cycled from -40°C to 60°C.
• the compressive force as a function of temperature was determined using the techniques described above for both silicone gel gaskets and gaskets according to the present embodiment of the invention. The results are shown in Fig. 5.
• the fill material for the embodiment of the invention described herein was hydrogel prepared as in Example C.
• the compressive force for the embodiment of the invention herein is dramatically higher at temperatures of less than 10°C, largely due to the dramatic volume expansion of the water based material in the core of the gasket.
• Example Gaskets with several water-containing fill materials were prepared as follows:
• the gasket was prepared according to the following procedure: a. Add the water to a mixing tank equipped with a Lightning mixer. Begin slow agitation and add the DASC and potassium sorbate. b. Blend the CMC, hydroxyethylcellulose and fumaric acid. Add these ingredients to the propylene glycol and stir until they are dispersed (normally no more than 2 min.). c. Add the glycol slurry to the DASC dispersion and stir for 15 min. d. Fill containers. e. Hold containers at room temperature for 48 hrs. before testing. 2. HYDROGELS BASED ON CROSSLINKED ACRYLIC ACID POLYMERS (Carbopol Polymers, B.F. Goodrich, Cleveland, Ohio, Bulletin IS-2)
• Carbopol resins are acrylic acid polymers. Individual resins vary by molecular weight and degree of crosslinking.
• the gasket was prepared according to the following procedure: a. Add Carbopol resin slowly to the vortex of the water being agitated. Add Carbopol resins as early in a formulation as possible. This allows for the longest possible mixing time which helps insure that the Carbopol resin is completely dispersed and hydrated. b. Neutralize the Carbopol resin, that is, increase the pH, as close to the end of the process as possible. This allows for the complete dispersion of the resin and other formulation ingredients prior to the Carbopol resin providing its highest viscosity. c. Fill parts with the resulting gel. 3. HYDROGEL BASED ON CROSSLINKED POLYPROPENOIC ACID (XU 40346 Super Absorbent Polymer, Dow Chemical, Midland, Michigan)
• XU 40346 is a partial sodium salt of crosslinked polypropenoic acid.
• the gasket was prepared according to the following procedure: a. Add the water to a mixing tank equipped with a propeller-type mixer. Begin agitation and add the XU 40346 resin, b. Fill parts with the resulting gel.
• the gasket was prepared according to the following procedure: a. Boil water and add the gelatine powder. b. Cool mixture to about 40°C. c. Fill containers with liquid mix. d. Chill samples until gelatine is firm. Experiments were conducted to determine the compressive force generated by the above water swelling polymers during cooling, and the results are shown in Fig. 6. In all cases, the compressive force generated by the seal is substantially higher using the invention herein than, for example, silicone rubber as the temperature is lowered. Similar results were obtained for tight fitting gaskets, and for both metal and plastic sealed surfaces. Table 3 summarizes the results of various compressive force retention experiments.
• Table 3 illustrates the compressive force retention of Hydoseal'" gaskets according to one embodiment of the invention herein at their minimum point, and compares these results to silastic J and silastic L. Results are illustrated at a number of different initial applied forces. As seen therein, the gaskets according to the invention herein consistently have much higher minimums than conventional gaskets.
• Fig. 7 illustrates the results of compressive force tests for various gaskets containing different ratios of rubber to Aqualon as described in the above example.
• the seals are thermally cycled, two types of phenomena occur.
• the rubber sleeve expands when heated and contracts during cooling.
• the hydrogel or water-containing compound increases in volume when the temperature decreases below 4°C or when it increases above 20°C.
• the sum of the volume changes at any given temperature could be either positive or negative depending on the volume ratio of rubber to hydrogel used in making the seal.
• Figs. 8a, 8b and 8c illustrate the mechanical configuration of a cable sealing gasket according to one aspect of the invention.
• the gasket includes a body 22 filled with a low coefficient of thermal expansion material or water-containing compound therein.
• This embodiment of the invention includes a seam 24 that allows application of the gasket to a cable even when the cable (not shown) cannot easily be "broken.”
• the seam includes portions 26 that run collinear with the underlying cable.
• the collinear sections are separated by seam portions 28 that run at an angle to the first portions, preferably perpendicular to the first portions.
• a force is applied to the faces of the gasket, thereby placing a force on adjoining faces of the seam sections 28.
• Such force may be applied by, for example, tightening of a nut against one face while holding the other face stationary with a raised face of an adjoining piece of equipment. Accordingly, even though the gasket contains a seam, the seam will prevent leaks along the seam at the compressed seam sections 28. Moreover, during cooling, the seam sections 28 will remain in close contact as a result of the low coefficient of expansion fill material in the gasket.
• Figs. 9a and 9b illustrate a gasket and associated a cable enclosure.
• the cable enclosure in Figs. 9a and 9b may be used with, for example, fiber optic, coaxial, or copper cables.
• the gasket 31b is made from separable pieces 30 and 32.
• the two pieces form halves of a circle with one or more cable and stud passageways 34.
• the gasket is made according to one of the embodiments using a body of, for example, silicon rubber filled with a low coefficient of thermal expansion filler.
• the two pieces of the gasket are brought together in a reenterable cable enclosure 36 that is used, for example, in protection of cable splices (not shown) .
• the cable enclosure has recessed portions 38 that are formed to receive the gasket 31. Extending from the recessed portion are studs 40. The gasket is placed in the recessed region with the studs passing through stud passageways 42.
• Fig. 9c illustrates an alternative embodiment of the invention in which the face of the gasket on one or more of the surfaces to be sealed is provided with a furrowed surface 43.
• the surfaces of the gasket portions that are to be joined are provided with similar furrowed surfaces 45. Such surfaces provide pressure points that will provide more effective sealing in many applications.
• Fig. 9d illustrates another alternative embodiment of a two piece gasket assembly.
• a flat slab of gasket material 47 is provided between the two furrowed gasket portions 45.
• Fig. 9e illustrates a two piece gasket with a lateral face 28 analogous in function to the embodiment shown in Fig. 8a. When pressure is exerted on the faces 28 the leak path formed by the seal break will be effectively blocked.
• FIGs. 10a and 10b illustrate an in-line enclosure for cable splices and the like.
• Fig. 10a shows the device in cross section without a cable
• Fig. 10b shows the device with an installed cable.
• the enclosure includes a body 36.
• a gasket 31 is held tightly against the body by way of a washer 44 and a threaded plunger 50 that engages the body, forcing the gasket into the recessed region therein.
• Figs. 11a and lib illustrate a butt splice closure using gaskets of the present invention.
• Fig. 11a illustrates the device in exploded view
• Fig. lib illustrates the device in a partially assembled configuration.
• two or more cables 60 enter the enclosure via a cap assembly 62 having cable apertures therein.
• the cap assembly and the body 64 have retaining walls 64 that are spaced apart a selected distance when the cap is place on the body.
• a seal 66 like those described above, is placed around the body between the retaining walls and held thereto with a steel band 68.
• An additional low temperature gasket 70 engages the cap and the cable inserted therein using a washer 74 and plunger 76.
• Figs. 12a and 12b illustrate a hybrid sealing system similar to the- above described embodiments having two abutting sections.
• Fig. 12a illustrates the seal system in cross section
• Fig. 12b is a perspective view.
• a ring of soft, compliant material 80 is placed in a ridge 82 around a central portion of the seal.
• This soft material will seal the walls of adjoining surfaces having minor imperfections that cannot easily be sealed by hard rubber gaskets. Such minor imperfections may arise from scratches, molding imperfections, or other similar defects.
• the material 82 is a soft, pliable, and tacky material.
• the cone penetrates to between about 80 to 360x10 _1 mm.
• the cone penetration value is between about 250 and 360.
• Suitable materials include gels (thermoset or thermoplastic, such as those described in copending U.S. application Serial No. 07/802,950, incorporated herein by reference for all purposes) , mastics, putties, pastes, polyisobutylene (crosslinked or not crosslinked) , high viscosity greases, highly extended rubbers, partially crosslinked rubbers or pressure sensitive adhesives.
• Figs. 13a and 13b provide cutaway and isometric views of a gasket similarly equipped with a ring of soft material 82 with a gasket of a cylindrical configuration. 1.
• the first set consisted of a sandwich configuration with a mastic ring compressed between two split tubular seals with glass beads.
• Control samples were also tested which consisted of two split tubular seals but, no mastic.
• the seams of the two seals were staggered so as to simulate a "step" seam. Although initially this was done to avoid making a mold for the rather complex shape, it turned out to be a good approach for making hybrid seals in a simple manner.
• Solid rubber seals containing a mastic ring failed overnight (i.e., in less than 2 cycles).
• Blass Bead-Based Seals with Mastic 13698-l-6a 151 (ongoing) 4.5 psi 13698-l-6b 151 (ongoing) 4.7 psi 13698-1-6C 151 (ongoing) 4.3 psi
• Solid Silicone Rubber with Mastic 13452-la 2 (failed) 0 psi Leak along cable 2 13452-lb 2 (failed) 0 psi Leak along cable 2 13452-lc 2 (failed) 0 psi Leak along cable 2
• Figs 14a and 14b illustrate an alternative embodiment of the invention in which rings 90 surround a portion of the outer perimeter of the gasket.
• Fig. 14a illustrates the invention at room temperature
• Fig. 14b illustrates the invention at a lower temperature, such as -40°C.
• Rings 90 have a higher coefficient of thermal expansion than either the body or the -fill material. Accordingly, when the gasket is cooled, the walls of the gasket are forced outwards due to the volume displacement of the gasket within the rings. The amount of displacement can easily be adjusted by adjusting the amount of the size of the rings 90 and relative coefficient of thermal expansion of the materials.
• the ring need only have a lower coefficient of thermal expansion than the body and not necessarily a low coefficient of thermal expansion.
• Rings according to Fig. 14 were tested in aluminum test fixtures and pressurized to 5 psi.
• the gaskets were thermally cycled from -40°C to +60°C.
• Figs. 15a to 15d illustrate additional embodiments of the invention.
• the versions shown in Fig. 15a to 15d can be used to produce thin-walled devices for either front access only (e.g., 15a) or for applications in which there is access from both sides. In the latter case, it is possible to pre-adjust either the inner or outer tubular gasket with a threaded ring. This feature could be useful in situations where there is a need to extend the sealing range of either gasket.
• the embodiments shown in Fig. 15 are referred to herein as thin walled enclosures.
• FIG. 15a front access is provided. Gasket displacement is varied by piston 1503 or gasket length.
• Fig. 15b access is provided on both sides.
• the outer gasket can be preadjusted with the threaded ring 1501.
• the outer threaded cap 1502 can compress both gaskets.
• Fig. 15e access is provided from both sides and the outer gasket is compressed by threaded ring 1501 while the threaded cap 1502 compresses the inner gasket.
• Fig. 15d illustrates a device with access from either side, and compression is provided by caps 1504.
• FIG. 16a to 16d show some examples of devices in which pistons and tubular gaskets are placed on both sides of the main body.
• Fig. 16 there are many variations that can be made depending on the type of application.
• the embodiments shown in Fig. 16 are referred to herein as inside/outside gasketed wall embodiments.
• the gaskets can be compressed independently by threaded caps or rings, or they can be compressed simultaneously by one threaded cap.
• Fig. 16a illustrates a device with front access where gasket displacement is varied by piston 1601 or gasket length.
• Fig. 16b illustrates a device where access is from both sides and where the cap 1603 compresses the outer gasket of the cap 1605.
• Fig. 16c illustrates a device with front access where the gaskets are independently compressed by threaded cap 1607 or ring 1609.
• Fig. 16d illustrates a device with front access wherein the inner gasket is adjusted with ring 1611 and both gaskets are compressed by cap 1615.
• FIGs-. 17a to 17c Examples of another version are shown in Figs-. 17a to 17c. These devices make use of only one piston to compress a tubular inner gasket. Sealing around the port or outer region is accomplished by the use of a flat gasket which is compressed by either an independent threaded ring or by the pulling action of the threaded cap on the main body.
• the embodiments in Fig. 17 are referred to herein as single piston embodiments.
• Fig. 17a illustrates a seal system in which front access is provided and both gaskets are individually compressed.
• Fig. 17b illustrates a seal system in which front access is provided and both gaskets are compressed.
• Fig. 17b illustrates a device with access from both sides and a flange 1701 assists in compressing the outer gasket.
• Fig. 17c illustrates a device with access from both sides in which both gaskets are compressed at the same time by cap 1703.
• Figs. I8a-18c One of the most important advantages over traditional gaskets and "0" rings is the fact that the ratio of length of gasket to piston displacement can be varied over a wide range, thus providing a wide sealing range capability. This is illustrated by Figs. I8a-18c.
• Fig. 18a provides the same compression on both gaskets while Figs. 18b and 18c show devices wherein one gasket is preferentially compressed by ring 1801.
• Seam sealing can be accomplished by allowing both gaskets to come in contact with each other through an opening along the seam. This is illustrated by the diagrams in Figs 19a to 19d, which embodiments are referred to as seam sealing embodiments.
• a solution to the problem is to encapsulate conductive microspheres or liquids within an elastomeric sleeve so that sealing and EMI/RFI protection can be achieved in a simple step.
• This approach lends itself to the production of all types of gaskets or sealing devices (O-rings, grommets, bushes, plugs, boots and flat or tubular gaskets) .
• Materials suitable for this application are electrically conductive solid and liquid materials (e.g., metal and metal alloys, graphite, carbon black, as well as conductive synthetic polymers, gels and liquids).
• the present invention provides a greatly improved method and device for forming seals in low temperature applications, and especially where thermal cycling is expected.
• the above description is illustrative and not restrictive. Many variations of the invention will become apparent to those of skill in the art upon review of this disclosure. Merely by way of example the various components have the invention have been illustrated with respect to various specific materials, but the scope of the invention is not so limited. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Sealing Material Composition (AREA)
• Gasket Seals (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1992
  • 1992-08-22 TW TW081106659A patent/TW201341B/zh active
• 1993
  • 1993-08-04 MX MX9304732A patent/MX9304732A/es unknown
  • 1993-08-06 JP JP6505588A patent/JPH08500140A/ja not_active Ceased
  • 1993-08-06 EP EP93918686A patent/EP0654131A1/de not_active Withdrawn
  • 1993-08-06 BR BR9306846A patent/BR9306846A/pt not_active Application Discontinuation
  • 1993-08-06 WO PCT/US1993/007416 patent/WO1994003743A1/en not_active Application Discontinuation
  • 1993-08-06 CA CA002141199A patent/CA2141199A1/en not_active Abandoned
  • 1993-08-06 AU AU48045/93A patent/AU4804593A/en not_active Abandoned
  • 1993-08-06 KR KR1019950700444A patent/KR950703130A/ko not_active Application Discontinuation
  • 1993-08-07 CN CN93116260A patent/CN1089703A/zh active Pending

Non-Patent Citations (1)

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