Moisture resistant seal for electrical cable assemblies

Abstract

A waterproof seal for electrical assemblies wherein an outer sheath of an electrical cable is removed to expose the wires and the insulation is removed from the wires to form a window of exposed electrical conductor, the electrical conductors being maintain apart from each other and contained in a cover that may comprise a connector, an epoxy applied to the electrical conductors to fill in all the space in and around the electrical conductors and the cover to form a waterproof seal that prevents water from wicking past the waterproof seal via an interior of the electrical cable.

Claims

1. A waterproof seal for an electrical assembly comprising: an electrical cable having: a first conductor comprising a plurality of twisted strands covered with a first insulation, the first conductor having a first length and having first and second ends; a second conductor comprising a plurality of twisted strands covered with a second insulation, the second conductor comprising a second length and having first and second ends; wherein the insulation is stripped away from the first conductor at a first location along a longitudinal length of the first conductor to form a first window of exposed twisted strands, and wherein the twisted strands are untwisted for at least a portion of the first window; wherein at least a portion of the untwisted strands in the first window are solidified into a first unitary conductive portion within the first window; wherein the insulation is stripped away from the second conductor at a second location along a longitudinal length of the second conductor to form a second window of exposed twisted strands, and wherein the twisted strands are untwisted for at least a portion of the second window; wherein at least a portion of the untwisted strands in the second window are solidified into a second unitary conductive portion within the second window; a covering positioned around the first and second windows; an epoxy material disposed in and around the first and second windows and filling any spaces between said covering and the first and second unitary conductive portions; and a bonding agent overlays a portion of an inside surface of the covering such that said epoxy bonds to the inside surface of said covering; wherein said covering prevents moisture from penetrating into said electrical cable, and wherein said epoxy material occupies spaces within said first and second windows to prevent water from wicking through said electrical cable.

2. The waterproof seal for electrical assemblies of claim 1, wherein the first window is axially offset from the second window.

3. The waterproof seal for electrical assemblies of claim 2, wherein the first and second windows do not overlap.

4. The waterproof seal for electrical assemblies of claim 1, wherein the first window axially aligns with the second window.

5. The waterproof seal for electrical assemblies of claim 4, further comprising a spacer positioned between the first and second conductors to maintain a distance between the first and second conductors.

6. The waterproof seal for electrical assemblies of claim 5, wherein said spacer is formed as a disc-shaped device that includes cutouts to receive the first and second conductors on an external radial surface of the spacer.

7. The waterproof seal for electrical assemblies of claim 6, wherein said spacer includes a plurality of protrusions on the external radial surface of the spacer.

8. The waterproof seal for electrical assemblies of claim 6, wherein said spacer includes an opening extending therethrough.

9. The waterproof seal for electrical assemblies of claim 1, wherein the covering comprises a connector.

10. The waterproof seal for electrical assemblies of claim 9, wherein the connector is form as a two-part assembly with an upper portion and lower portion.

11. The waterproof seal for electrical assemblies of claim 10, wherein the connector comprises at least one O-ring on the lower portion.

12. The waterproof seal for electrical assemblies of claim 10, wherein the lower portion is formed as a ninety-degree connector.

13. The waterproof seal for electrical assemblies of claim 10, wherein the upper and lower portions sandwich said electrical cable to provide strain relief for the waterproof seal.

14. The waterproof seal for electrical assemblies of claim 1, wherein the first and second unitary conductive portions are formed by soldering or ultrasonic welding.

15. The waterproof seal for electrical assemblies of claim 1, wherein the covering comprises a shrink tubing.

16. The waterproof seal for electrical assemblies of claim 1, wherein the electrical cable comprising a third conductor comprising a plurality of twisted strands covered with a third insulation, the third conductor comprising a third length and having first and second ends; wherein the insulation is stripped away from the third conductor at a third location along a longitudinal length of the third conductor to form a third window of exposed twisted strands, and wherein the twisted strands are untwisted for at least a portion of the third window; wherein at least a portion of the untwisted strands in the third window are solidified into a third unitary conductive portion within the third window; said covering is positioned around all of the first, second and third windows; and said epoxy material is disposed in all of the first, second and third windows filling any spaces between said covering and all of the first, second and third unitary conductive portions.

17. The waterproof seal for electrical assemblies of claim 1, wherein the waterproof seal is positioned in a snake device that contains the electrical cable and is designed to connect to a light fixture.

18. A method for providing a waterproof seal for electrical assemblies comprising an electrical cable having a first and a second conductor each having a plurality of twisted strands and each surrounded by a first and a second insulation respectively, the method comprising the steps of: stripping away the insulation of the first conductor at a first location along a longitudinal length of the first conductor to form a first window of exposed twisted strands without cutting the twisted strands; untwisting the twisted strands of the first conductor in the first window; solidifying at least a portion of the untwisted strands in the first window to form a first unitary conductive portion within the first window; stripping away the insulation of the second conductor at a second location along a longitudinal length of the second conductor to form a second window of exposed twisted strands without cutting the twisted strands; untwisting the twisted strands of the second conductor in the second window; solidifying at least a portion of the untwisted strands in the second window to form a second unitary conductive portion within the second window; positioning a covering around the first and second windows; applying an epoxy material to the first and second windows and filling in any spaces between the covering and the first and second unitary conductive portions; and overlaying a bonding agent on a portion of an inside surface of the covering such that the epoxy bonds to the inside surface of the covering; wherein the covering prevents moisture from penetrating into the electrical cable, and wherein the epoxy material occupies spaces within the first and second windows to prevent water from wicking through the electrical cable.

19. The method of claim 18, wherein the first window is axially offset from the second window.

20. The method of claim 18, further comprising the step of positioning a spacer between the first and second conductors to maintain a distance between the first and second conductors.

21. The method of claim 20, wherein the spacer is formed as a disc-shaped device that includes cutouts to receive the first and second conductors on an external radial surface of the spacer.

22. The method of claim 18, wherein the covering is a connector formed as a two-part assembly with an upper portion and lower portion.

23. The method of claim 22, further comprising the step of positioning at least one 0-ring on the lower portion.

24. The method of claim 22, further comprising the step of forming the lower portion as a ninety-degree connector.

25. The method of claim 22, further comprising the step of sandwiching the electrical cable between the upper and lower portions to provide strain relief for the waterproof seal.

26. The method of claim 18, wherein the step of solidifying the untwisted strands of the first and second conductors is performed by soldering or ultrasonic welding.

27. A method for providing a waterproof seal for electrical assemblies comprising an electrical cable having a first and a second conductor each surrounded by a first and a second insulation respectively, the method comprising the steps of: stripping away the insulation of the first conductor at a first location along a longitudinal length of the first conductor to form a first window of exposed electrical conductor without cutting the electrical conductor; stripping away the insulation of the second conductor at a second location along a longitudinal length of the second conductor to form a second window of exposed electrical conductor without cutting the electrical conductor; positioning a covering around the first and second windows; applying an epoxy material to the first and second windows and filling in any spaces between the covering and the first and second exposed electrical conductors; and overlaying a bonding agent on a portion of an inside surface of the covering such that the epoxy bonds to the inside surface of the covering; wherein the covering prevents moisture from penetrating into the electrical cable, and wherein the epoxy material occupies spaces within the first and second windows to prevent water from wicking through the electrical cable, and providing a two-part assembly with an upper portion and a lower portion that encloses the covering.

28. The method of claim 27, further comprising the step of positioning a spacer between the first and second conductors to maintain a distance between the first and second conductors.

29. The method of claim 27, further comprising the step of positioning at least one O-ring on the lower portion.

30. The method of claim 27, further comprising the step of forming the lower portion as a ninety-degree connector.

31. The method of claim 27, further comprising the step of sandwiching the electrical cable between the upper and lower portions to provide strain relief for the waterproof seal.

32. The method of claim 27, wherein the step of solidifying the strands of the first and second conductors is performed by soldering or ultrasonic welding.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an illustration of an electrical cable with the insulation removed to expose the electrical conductor according to an initial step of the invention.

(2) FIG. 1A is an illustration of the electrical conductor untwisted and a portion of the plurality of strands formed into a unitary conductive portion according to another step of the invention.

(3) FIG. 1B is an illustration of a covering being applied over the electrical cable with an epoxy to cover the exposed electrical conductor according to another step of the invention.

(4) FIG. 1C is an illustration of the moisture seal according to the invention.

(5) FIG. 1D is an illustration of the moisture seal according to FIG. 1 and including three electrical conductors.

(6) FIG. 2 is an illustration of the moisture seal according to FIG. 1D with three windows created that are axially aligned.

(7) FIG. 3 is an illustration of the moisture seal according to FIG. 1D with three windows created that are slightly axially shifted relative to each other.

(8) FIG. 4 is an illustration of the moisture seal according to FIG. 1D with three windows created that are axially shifted relative to each other so that there is no axial overlap between the windows.

(9) FIG. 5 is a cross section at A-A according to FIGS. 2-4.

(10) FIG. 6 is a cross section at B-B according to FIG. 2.

(11) FIG. 7 is a cross section at C-C according to FIG. 3.

(12) FIG. 8 is a cross section at D-D according to FIG. 4.

(13) FIG. 9 is an illustration of the moisture seal according to FIG. 1D further illustrating the spacer.

(14) FIG. 10 is an illustration of the spacer according to FIG. 9.

(15) FIGS. 11-12 is an illustration of a ninety-degree connector with strain relief that incorporates the moisture seal according to FIG. 1D.

(16) FIG. 13 is an exploded version of the ninety-degree connector with strain relief according to FIGS. 11-12.

(17) FIG. 14 is a snake assembly for a light fixture that incorporates the moisture seal according to FIG. 1D.

DETAILED DESCRIPTION OF THE INVENTION

(18) Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views.

(19) FIG. 1 depicts and illustration of an electrical cable 102 that can be used with the moisture seal according to one embodiment of the invention. The electrical cable 102 comprises an electrical conductor 104 surrounded by an insulation 106. The electrical conductor 104 can be made of any suitable material but will typically comprise copper or aluminum.

(20) In FIG. 1 a portion of the insulation 106 is stripped away from the electrical cable 102 to expose the electrical conductor 104 and forming a window 108 of exposed electrical conductor. Care must be taken to not cut or damage the electrical conductor during this process. The exposed electrical conductor is formed of a plurality of twisted strands 110 that form the overall electrical conductor 104.

(21) Referring now to FIG. 1A, it can be seen that the twisted strands have been untwisted to form a plurality of relatively straight strands 112. Also illustrated is a unitary conductive portion 114 that is positioned within the window 108.

(22) The unitary conductive portion 114 may be formed by either applying solder to the relatively straight strands 112 or by ultrasonic welding the relatively straight strands 112. It will be understood by those of skill in the art that ultrasonic welding utilizes acoustic vibrations that are applied to the plurality of strands that will be held together under pressure to create a solid-state weld. When solder is utilized, any suitable well-known solder can be used such as, a tin-silver-copper (Sn—Ag—Cu, or SAC) solder.

(23) It should be noted that the twisted strands are straightened, which more easily allows for the formation of the unitary conductive portion 114, particularly in the case when the solder-method is used.

(24) Turning to FIG. 1B, a cover 116 is in the process of being applied to the electrical cable 102. The cover 116 may comprise any type of suitable material that can shrink to enclose the window 108.

(25) In one configuration a first end 118 of the cover 116 is adhered to the electrical cable 102 while the remaining end 120 remains enlarged to allow access to the window 108. An inside surface of the cover 116 may be covered with an adhesive 122 and is designed to bond with an epoxy 124 that will be applied over top of the electrical cable 102 and in the window 108 as better seen in FIG. 10.

(26) The epoxy 124 may be provided as a thermoplastic or thermoset material. The epoxy 124 may further comprise a hot melt adhesive (HMA). The adhesive may be provided as, for example, a one-part or two-part epoxy cement.

(27) It should be noted that the cover 116 may as shown in FIG. 1B comprise a heat shrink material or may comprise an overmold material formed as a thermoplastic material such as is depicted in FIGS. 11-13. The thermoplastic material may be polyethylene (PE), polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), ethylene propylene diene monomer (EPDM) or Chlorobutyl Rubber.

(28) Referring now to FIG. 10, the waterproof seal 100 is shown with the epoxy fully applied and the covering in place over the exterior of the electrical cable 102 and fully enclosing the window 108. As can be seen in the figure, the epoxy fully surrounds the electrical conductor 104 and fills in all of the space in window 108.

(29) In this configuration, any water that may enter the electrical cable 102 and travel along the inside of the electrical cable 102 in the spaces located between the electrical conductor 104 and the insulation 106 will encounter a moisture barrier at the waterproof seal 100. The electrical conductor 104 comprises the unitary conductive portion 114 that is a solid mass, which would prevent any water from passing through it. That unitary conductive portion 114 is surrounded by the epoxy 124, which fills in all of the spaces in and around the window 108 preventing any moisture from passing through it. The adhesive 122 provided on the inside surface of the cover 116 is designed to bond with the epoxy 124 to prevent any water from passing between the inside surface of the cover and the outer surface of the epoxy. The result is a moisture seal that in practice, prevents water from passing through the seal and entering the light fixture. This seal even functions in very wet or submerged areas where a relatively large amount of water has gotten into the electrical cable.

(30) While only a single electrical cable is shown in FIG. 1-10, FIG. 1D shows and example of three electrical cables using the moisture seal 100. For example, it can be seen that electrical cables 102, 102′, 102″ are depicted and electrical conductors 104, 104′, 104″ with insulation 106, 106′, 106″ stripped away are shown within window 108. Each of the electrical conductors 104, 104′, 104″ comprise a unitary conductive portion 114, 114′, 114″ that is contained within the epoxy 124 and further enclosed by the cover 116.

(31) Also shown in FIG. 1D is a spacer 130, which is shown in greater detail in FIGS. 9 and 10. The spacer will be discussed in connection with those figures.

(32) As discussed in connection with FIG. 10, the cover 116 may comprise a heat shrink material or may comprise an overmold material formed as a thermoplastic material such as is depicted in FIGS. 11-13. While three wires (power, neutral, ground) are depicted in FIG. 10, it is contemplated that any number of wires may be used with the moisture seal where each electrical conductor would be subject to the sonic welding or soldering process and enclosed with the epoxy and cover to form the moisture seal.

(33) FIGS. 2-4 show various configurations of the configuration according to FIG. 1D. For example, electrical cables 102, 102′, 102″ are each shown with respective electrical conductors 104, 104′, 104″ having insulation 106, 106′, 106″ removed.

(34) FIG. 2 shows the windows where the insulation has been removed from the underlaying electrical conductor all align axially. While the figures are not adjusted to show the overall length of the moisture seal being variable, it will be understood by those of skill in the art that the length of the moisture seal can be minimized to essentially just slightly longer than the length of one window as all of the windows align. This can result in a length for the moisture seal being as little as 0.38 inches (approx. 0.97 cm) in length.

(35) Alternatively, if a minimized length is not required, the configuration in FIG. 3 where the windows are axially shifted from each other could be utilized. The axial shift can be seen with reference to windows 108, 108′, 108″. Finally, in FIG. 4, the windows are offset such that each are axially shifted to the point where none of the windows axially overlap each other, which is illustrated by windows 108, 108′, 108″. For the configuration in FIG. 4, the moisture seal could be approximately one inch (approx. 2.54 cm) in length.

(36) FIGS. 5-8 show cross-sectional views of the electrical cables 102, 102′, 102″ at cross-sections A-A, B-B, C-C and D-D where the various cross sections of the moisture seal are shown.

(37) Referring now to FIGS. 9-10, for applications where it is desirable to provide a moisture-blocking structure with an axially minimized length, such as shown in FIGS. 1D and 2, an alternative is to provide the windows axially aligned with each other to limit the total axial length of the combined windows to the length of one window. However, due to the possibility of the electrical conductors physically contacting each other or being so close that arcing is a danger, a spacer can be used to maintain a radial distance between the electrical conductors to prevent a short-circuit.

(38) As can be seen in connection with FIG. 9, the axial length of the spacer 130 can approximately equal the length of the window. FIG. 10 shows the spacer 130 in greater detail. For example, the spacer includes a central portion 132 that includes a central opening 138 and cutouts 134, 134′, 134″ designed to receive electrical conductors 104, 104′, 104″ respectively. In this configuration the electrical conductors 104, 104′, 104″ are maintained at about a 120-degree radial position relative to each other. Also shown on spacer 130 are protrusions 136, 136′, 136″ that extend radially outward relative to central portion 132. The spacer 130 can be made from any type of insulating material that is known in the art and will be selected to have a good bonding factor with the epoxy 124.

(39) FIGS. 11-13 show another configuration for the moisture seal where, instead of using a shrink cover, a connector 140 is used in the form of a ninety-degree electrical connector that can be coupled to a light fixture. In this case, the electrical cable 102 is connected to the electrical connector 140 and may include a strain relief fitting. The connector 140 is formed as a ninety-degree fitting and may include a protrusion 142 designed mechanically connect with a light fixture. In one configuration, the protrusion may be a threaded portion, while in another configuration it may comprise a friction fitting that is designed to be inserted directly into an opening. It is contemplated that the connector 140 will be provided as a liquid tight assembly and include one or more O-rings 144 that are designed to form a seal with the inside surface of an opening (not shown), such as, in a light fixture. The electrical cable 102 enters the connector 140 at a first end and exits the connector 140 from the protrusion 142. The wires can then be connected to the equipment in accordance with the manufacturer's recommendations.

(40) As seen in FIG. 13, an exploded view of the connector 140 illustrates the electrical cable 102, the windows where the outer sheath of the electrical cable 102 is removed and the insulation 106, 106′, 106″ is stripped away from the electrical conductors 104, 104′, 104″ in order to create the moisture seal as previously discussed. The exploded view illustrates that the connector 140 is formed as two pieces including a lower portion 146 and an upper portion 148.

(41) The lower and upper portions 146, 148 of the connector 140 may be provided as molded thermoplastic material as previously described. When the electrical cable 102 is inserted in the connector 140, the lower portion 146 and upper portion 148 sandwich the electrical cable 102 and provide strain relief. As previously discussed, an epoxy 124 may be injected into the connector 140 to surround and encase the electrical conductors 104, 104′, 104″, which will have been treated to form unitary conductive portions as previously discussed. It is contemplated that the inner surface of the lower and upper portions 146, 148 may be treated with the adhesive 122 to ensure that the epoxy forms a solid bond with the lower and upper portions 146, 148. The result is a very compact and rugged moisture blocking configuration that takes up minimal space.

(42) The upper portion 148 may further be provided with a mounting hole 149 that is designed to receive a mounting element so that the connector 140 can be secured in a manner desired.

(43) Referring now to FIG. 14, a snake 150 is provided that may be positioned with a cavity of a light fixture (not shown). The snake 150 may comprise any suitable plastic material as previously described that allows for protection and articulation of the power cable. The snake 150 comprises a plurality of articulating segments 152 and allow the snake to be flex and bend to a desired shape.

(44) The electrical cable 102 is maintained inside of the snake 150 and extends to a connector 154 integral with the snake 150. While the drawing only illustrates a connector 154 on one end of the snake 150, it will be understood by those of skill in the art that a connector 154 can be provided at both ends of the snake 150, one to plug into the light fixture (not shown) and one to plug into a power connector (not shown).

(45) The moisture seal may be provided integral with the snake on one or both ends of the snake 150 and formed in a manner consistent with that previously described. It is further contemplated that the snake 150 may be formed as a liquid tight structure.

(46) Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.