초록 ▼

A coupling for non-metallic flexible electrical conduit is formed of a one piece lightweight molded thermoplastic cylindrical sleeve having a pair of threads extending inwardly toward opposite ends. Spaced axially inwardly from the inner end of each thread is an annular sealing ring having a sloped

A coupling for non-metallic flexible electrical conduit is formed of a one piece lightweight molded thermoplastic cylindrical sleeve having a pair of threads extending inwardly toward opposite ends. Spaced axially inwardly from the inner end of each thread is an annular sealing ring having a sloped leading face and a perpendicular trailing face with the faces intersecting at a sharp annular edge. Lengths of conduit are engaged over opposite ends of the coupling and rotated to advance the conduit lengths over the sleeve. A liquid tight engagement is effective between each conduit length and the coupling when the conduit length advances past the sealing ring.

대표청구항 ▼

Having thus described the invention, there is claimed as new and desired to be secured by Letters Patent: 1. A liquid tight spliced section of flexible non-metallic electrical conduit, the spliced section including a coupling, the coupling comprising a one-piece molded thermoplastic body, the body

Having thus described the invention, there is claimed as new and desired to be secured by Letters Patent: 1. A liquid tight spliced section of flexible non-metallic electrical conduit, the spliced section including a coupling, the coupling comprising a one-piece molded thermoplastic body, the body including a sleeve having a longitudinal axis, a cylindrical surface with a uniform diameter, a pair of opposed axial ends comprising a first end and a second end, a first thread extending axially along the sleeve from the first end, a second thread extending axially along the sleeve from the second end, both threads projecting radially from the cylindrical surface, each thread having an inner end, the sleeve further including a first annular sealing ring projecting radially from the cylindrical surface and being spaced axially from the inner end of the first thread, the cylindrical surface being free of radial projections between the inner end of the first thread and the first annular sealing ring, a second annular sealing ring projecting radially from the cylindrical surface and being spaced axially from the inner end of the second thread, the cylindrical surface being free of radial projections between the inner end of the second thread and the second annular sealing ring, each sealing ring having a sloped leading face and a trailing face, the trailing face of each sealing ring lying in a plane perpendicular to the longitudinal axis, the trailing face and the leading face of each sealing ring intersecting at a sharp annular edge, the spliced section of non-metallic electrical conduit comprising a first length of flexible non-metallic electrical conduit having a bore and a second length of flexible non-metallic electrical conduit having a bore, the bore of the first length being positioned over the first thread and the first sealing ring with the sharp annular edge of the first sealing ring engaging the bore and sealing the first length to the coupling to preclude the entry of liquids and moisture into the bore of the first length, the bore of the second length being positioned over the second thread and the second sealing ring with the sharp annular edge of the second sealing ring engaging the bore and sealing the second length to the coupling to preclude the entry of liquids and moisture into the bore of the second length, a portion of the bore of the first length in registration with a portion of the cylindrical surface of the sleeve between the inner end of the first thread and the first annular sealing ring being free to deflect radially inwardly toward the cylindrical surface, a further portion of the bore of the first length in registration with a further portion of the cylindrical surface spaced axially from the trailing face of first annular sealing ring being free to deflect radially inwardly toward the cylindrical surface, a portion of the bore of the second length in registration with a portion of the cylindrical surface of the sleeve between the inner end of the second thread and the second annular sealing ring being free to deflect radially inwardly toward the cylindrical surface, a further portion of the bore of the second length in registration with a portion of the cylindrical surface spaced axially from the trailing face of the second annular sealing ring being free to deflect radially inwardly toward the cylindrical surface, the section further including at least one electrical lead extending through the first length, through the coupling and through the second length whereby at least one electrical lead is maintained free from contact with liquids and moisture whereby the at least one electrical lead is maintained free of contact with liquids and moisture. 2. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the coupling body is symmetric about a plane transverse to the longitudinal axis and equidistantly spaced from the axial ends. 3. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the threads comprise buttress threads, whereby a high tensile strength splice is attained. 4. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 further including a flange projecting radially from the cylindrical surface, the flange lying in a plane perpendicular to the longitudinal axis and spaced equidistantly between the first end and the second end. 5. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the first thread and the second thread have a thread height in the order of 0.8 mm and a thread pitch in the order of 5.0 mm. 6. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the leading face of each sealing ring is at an angle of approximately 30° relative to the longitudinal axis. 7. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the first thread and the second thread have the same thread height, the sharp annular edge being spaced from the sleeve a radial distance at least as great as the thread height. 8. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 1 wherein the portion of the bore of the first length in registration with the portion of the cylindrical surface between the inner end of the first thread and the first annular sealing ring is in substantially abutting contact with the cylindrical surface and the portion of the bore of the second length in registration with the portion of the cylindrical surface between the inner end of the second thread and the second annular sealing ring is in substantially abutting contact with the cylindrical surface. 9. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 8 wherein the portion of the bore of the first length in registration with the portion of the cylindrical surface spaced axially from the trailing face of the first annular sealing ring is in substantially abutting contact with the cylindrical surface and the portion of the bore of the second length in registration with the portion of the cylindrical surface spaced axially from the trailing face of the second annular sealing ring is in substantially abutting contact with the cylindrical surface. 10. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 8 wherein the portion of the bore of the first length in registration with the portion of the cylindrical surface between the inner end of the first thread and the first annular sealing ring is in substantially abutting contact with the cylindrical surface and the portion of the bore of the second length in registration with the portion of the cylindrical surface between the inner end of the second thread and the second annular sealing ring. 11. A liquid tight section of flexible non-metallic electrical conduit, the section including a length of flexible non-metallic electrical conduit and a coupling, the coupling comprising a one piece molded thermoplastic body, the body including a sleeve having a longitudinal axis, the sleeve having a cylindrical surface with a uniform diameter suitable for engagement within the length of flexible non-metallic electrical conduit, a buttress thread projecting radially from the cylindrical surface and advancing axially along the sleeve from a first end of the sleeve toward a second end of the sleeve, the thread terminating at a point distant from the second end of the sleeve and an annular sealing ring projecting radially from the cylindrical surface and being axially spaced along the cylindrical surface between the point and the second end of the sleeve, the cylindrical surface being free of radial projections between the point and the sealing ring, the sealing ring having a sloped leading face directed toward the buttress thread and a trailing face directed toward the one end, the trailing face and the leading face intersecting at a sharp annular edge, the length of flexible non-metallic electrical conduit having a bore, the bore being positioned over the first end of the sleeve, the buttress thread and the sealing ring, with the sharp annular edge engaging the bore and sealing the length of conduit to the coupling to preclude entry of liquids and moisture into the bore, a portion of the bore in registration with the portion of the cylindrical surface between the point and the sealing ring being free to deflect radially inwardly toward the cylindrical surface, a portion of the bore in registration with a portion of the cylindrical surface between the trailing face of the sealing ring and the second end of the sleeve being free to deflect radially inwardly toward the cylindrical surface, the liquid tight section further including at least one electrical lead extending through the flexible non-metallic conduit and through the coupling whereby the at least one electrical lead is maintained free from contact with liquids and moisture. 12. A liquid tight section of flexible non-metallic electrical conduit as constructed in accordance with claim 11, wherein the thread is provided with a pitch in the order of 5.0 mm and a thread height in the order of 0.8 mm. 13. A liquid tight section of flexible non-metallic electrical conduit as constructed in accordance with claim 11, wherein the leading face of the sealing ring is sloped in the order of 30° relative to the longitudinal axis. 14. A liquid tight spliced section of flexible non-metallic electrical conduit as constructed in accordance with claim 11 wherein the portion of the bore in registration with the portion of the cylindrical surface between the point and the sealing ring is in substantially abutting contact with cylindrical surface. 15. A method of fabricating the liquid tight spliced section of flexible non-metallic electrical conduit of claim 1, the method comprising the steps of: a) selecting first and second lengths of non-metallic flexible electrical conduit to be spliced, b) inserting a bore of the first length of flexible non-metallic conduit over the first end of the cylindrical sleeve, c) inserting a bore of the second length of flexible non-metallic electrical conduit over the second end of the cylindrical sleeve, d) rotating each length of conduit relative to the sleeve to engage the respective threads and advance the conduit lengths along the sleeve and over the sealing rings, e) deflecting a portion of the bore of the first length in registration with the portion of the cylindrical surface between the inner end of the first thread and the first annular sealing ring radially inwardly toward the cylindrical surface, f) deflecting a portion of the bore of the second length in registration with the portion of the cylindrical surface between the inner end of the second thread and the trailing face of second annular sealing ring radially inwardly toward the cylindrical surface, and g) threading at least one electrical lead through the first length of conduit, through the coupling and through the second length of conduit. 16. A liquid tight section of flexible non-metallic electrical conduit, the section including a coupling, the coupling comprising a one piece molded thermoplastic body, the body including a sleeve having a first end and a second end, the sleeve having a cylindrical surface with a uniform diameter suitable for engagement within the section of flexible non-metallic electrical conduit, a thread projecting radially from the cylindrical surface and advancing axially along the sleeve from the first end of the sleeve, the thread terminating at a point distant from the second end of the sleeve, an annular sealing ring projecting radially from the cylindrical surface and being axially spaced from the point, the cylindrical surface being free of radial projections between the point and the annular sealing ring, the sealing ring having a sloped leading face directed toward the thread and a trailing face, the trailing face and the leading face intersecting at a sharp annular edge, the section of flexible non-metallic electrical conduit having a bore, the bore being positioned over the first end of the sleeve, the buttress thread and the sealing ring, with the sharp annular edge engaging the bore and sealing the section of flexible non-metallic electrical conduit to the coupling to preclude entry of liquids and moisture into the bore, a portion of the bore being in abutting contact with a portion of the cylindrical surface between the point and the annular sealing ring, the liquid tight section further including at least one electrical lead extending through the flexible non-metallic conduit and through the coupling whereby the at least one electrical lead is maintained free of contact with liquids and moisture. 17. A method of fabricating the liquid tight section of flexible non-metallic electrical conduit of claim 16, the method comprising the steps of: a) selecting a length of non-metallic flexible electrical conduit, b) inserting the bore of the length of flexible non-metallic conduit over the first end of the cylindrical sleeve, c) rotating the length of conduit relative to the sleeve to engage the thread and advance the length of conduit along the sleeve and over the sealing ring, and d) threading at least one electrical lead through the length of conduit and through the coupling. 18. A liquid tight section of flexible non-metallic electrical conduit as constructed in accordance with claim 16, wherein the thread is provided with a pitch in the order of 5.0 mm and a thread height in the order of 0.8 mm.