DUAL WALL CO-EXTRUDED CORRUGATED TUBING

Abstract: Dual wall co-extruded corrugated tubing (20) which includes an outer protective layer (22) fabricated from a relatively rigid plastic material, such as polypropylene or nylon, which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for the dual wall co-extruded corrugated tubing (20) and an inner sealing layer (24) fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE), to provide a sealing surface for the dual wall co-extruded corrugated tubing (20).

Description: INVENTION: DUAL WALL CO-EXTRUDED CORRUGATED TUBING SPECIFICATION To All Whom It May Concern: Be it known that we, Kenneth R. Chenoweth, a citizen of the United States of America, having a mailing address of 2711 Work Road; Ravenna, Ohio 44266; Wayne T. Heverly, a citizen of the United States of America, having a mailing address of 2309 Suncrest Drive; Cuyahoga Falls, Ohio 44221-3521; and Russell A. Murray, a citizen of the United States of America, having a mailing address of 1140 Indigo Lane; Waukee, Iowa 50263; have invented certain new and useful improvements in DUAL WALL CO-EXTRUDED CORRUGATED TUBING of which the following is a specification. BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to new and novel improvements in dual wall co-extruded corrugated tubing. More particularly, the present invention relates to dual wall co-extruded corrugated tubing which includes an outer protective layer which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance and an inner sealing layer which provides a sealing surface for the dual wall co-extruded corrugated tubing. Extruded corrugated tubing is widely used in applications where flexibility of the tubing is desirable, such as in various major household appliances, such as dishwashers and washing machines, as well as- in automotive, plumbing and other applications. Prior art extruded corrugated tubing is often fabricated from a relatively rigid plastic material, such as polypropylene or nylon, if crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance is desired. However, such prior art extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, is difficult to seal onto other components due to the relatively rigid nature of the plastic materials used. On the other hand, prior art extruded corrugated tubing is sometimes fabricated from a softer, more ductile material, such as a thermoplastic elastomer (TPE) , if sealing the extruded corrugated tubing onto other components is desirable. However, such prior art extruded corrugated tubing fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , does not provide the crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance provided by prior art extruded corrugated tubing fabricated from more rigid plastic materials, such as polypropylene or nylon. If, in prior art extruded corrugated tubing, it is desired to provide both crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance, as well as the ability to seal the extruded corrugated tubing onto other components, an extruded corrugated tubing assembly is sometimes used which is fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one or more end seal(s) fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) . While such extruded corrugated tubing assemblies do provide enhanced crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance, as well as the ability to seal the extruded corrugated tubing assembly onto other components, joining the end seal(s) to the length of extruded corrugated tubing is generally a separate, additional operation, and thus the cost of fabricating such extruded corrugated tubing assemblies is often more expensive than desirable. In addition, achieving a good joint between the end seal(s) and the length of extruded corrugated tubing is sometimes difficult to consistently achieve. One prior art multi-layer extruded corrugated tubing arrangement is seen in United States Patent No. 5,792,532 to Pfleger, issued August 11, 1998, for "Polymer Tubing." This issued United States patent discloses a polymer tubing which may include an inner layer which is inert in respect to the medium being conducted, an intermediate layer which is resistant to pressure and mechanical effects and a very soft polymer outer layer on the surface of the polymer tubing for noise damping. Other prior art multi-layer extruded corrugated tubing arrangements are disclosed in United States Patent No. 4,790,975 to Jarvenkyla, et al., for a "Method and Device for Extrusion of a Double Wall Plastics Pipe"; United States Patent No. 5,305,799 to Dal Palύ for a "Flexible Conduit for Vehicle Engine Coolant Circuits" and United States Patent No. 5,706,864 to Pfleger, issued January 13, 1998, for "Coolant Conduits." However, to applicant's knowledge, none of these prior art extruded corrugated tubing arrangements include an outer protective layer which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance and an inner sealing layer which provides a sealing surface for the dual wall co-extruded corrugated tubing. Accordingly, an object of the present invention is the provision of dual wall co-extruded corrugated tubing which includes an outer protective layer which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance and an inner sealing layer which provides a sealing surface for the dual wall co-extruded corrugated tubing. Another object of the present invention is the provision of dual wall co-extruded corrugated tubing which is cost effective to fabricate. Yet another object of the present invention is the provision of dual wall co-extruded corrugated tubing which is fabricated as an integral one-piece component in a single operation. Still another object of the present invention is the provision of dual wall co-extruded corrugated tubing which is particularly suitable for use in heavy household appliances, such as dishwashers and washing machines. These and other objects of the present invention are attained by dual wall co-extruded corrugated tubing which includes an outer protective layer fabricated from a relatively rigid plastic material, such as polypropylene or nylon, which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for the dual wall co-extruded corrugated tubing and an inner layer fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , to provide a sealing surface for the dual wall co-extruded corrugated tubing. The dual wall co-extruded corrugated tubing is preferably fabricated as an integral one-piece component in a single operation and replaces prior art single layer extruded corrugated tubing fabricated from, for example, polypropylene, nylon or a thermoplastic elastomer (TPE) material, as well as extruded corrugated tubing assemblies which are fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one or more end seal(s) which are fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , and which are attached to one or both ends of the length of extruded corrugated tubing in a separate operation. Other advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings . BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a prospective view of a prior art extruded corrugated tubing assembly which is fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one (1) end seal which is fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , the one (1) end seal being attached to the length of extruded corrugated tubing in a separate operation. Figure 2 is a side elevational view shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a first preferred embodiment of the present invention. Figure 3 is an exploded cross-sectional view of the first preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 2 taken from circle 3 - 3 in Figure 2. Figure 4 is a side elevational view, shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a second preferred embodiment of the present invention. Figure 5 is a first exploded cross-sectional view of the second preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 4 taken from circle 5 - 5 in Figure 4. Figure 6 is a second exploded cross-sectional view of the second preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 4 taken from circle 6 - 6 in Figure 4. Figure 7 is a side elevational view, shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a third preferred embodiment of the present invention. Figure 8 is an exploded cross-sectional view of the third preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 7 taken from circle 8 - 8 in Figure 7. DETAILED DESCRIPTION OF THE DRAWINGS In the following detailed description of a first preferred embodiment of the present invention, a second preferred embodiment of the present invention and a third preferred embodiment of the present invention, reference is made to the accompanying drawings which, in conjunction with this detailed description, illustrate and describe a first preferred embodiment, a second preferred embodiment and a third preferred embodiment of dual wall co-extruded corrugated tubing in accordance with the present invention. Referring first to Figure 1, which shows a prospective view of a prior art extruded corrugated tubing assembly which is fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one (1) end seal which is fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , the one (1) end seal being attached to the length of extruded corrugated tubing in a separate operation, the prior art extruded corrugated tubing assembly being generally identified by reference number 10, prior art extruded corrugated tubing assembly 10 includes a length of extruded corrugated tubing 12 fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and end seal 14 which is fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) . End seal 14 is typically attached to the length of extruded corrugated tubing 12 in a separate operation. Referring now to Figures 2 and 3, which illustrate a side elevational view, shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a first preferred embodiment of the present invention and an exploded cross-sectional view of the first preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 2 taken from circle 3 - 3 in Figure 2, respectively, dual wall co-extruded corrugated tubing, generally identified by reference number 20, preferably includes outer protective layer 22 which is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and inner sealing layer 24 which is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) . Outer protective layer 22 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 20 and inner sealing layer 24 provides a sealing surface for dual wall co-extruded corrugated tubing 20. Dual wall co-extruded corrugated tubing 20 is preferably fabricated as an integral one-piece component in a single operation and replaces prior art single layer extruded corrugated tubing fabricated from, for example, polypropylene, nylon or a thermoplastic elastomer (TPE) material, as well as extruded corrugated tubing assemblies which are fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as ' polypropylene or nylon, and one (1) or more end seal(s) which are fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE), and the one (1) or more end seal(s) are attached to one or both ends of the length of extruded corrugated tubing in a separate operation. Dual wall co-extruded corrugated tubing 20 in accordance with the present invention is anticipated to be used in major household appliances, such as dishwashers and washing machines, as well as in automotive, plumbing and other applications. The inside diameter of dual wall co-extruded corrugated tubing 20 is preferably in the range of one quarter (1/4) of an inch to four (4) inches and more preferably is in the range of three eighths (3/8) of an inch to one and one half (1 1/2) inches. In the preferred embodiment of dual wall co-extruded corrugated tubing 20 shown in Figures 2 and 3, outer protective layer 22 is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. Outer protective layer 22 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 20. Inner sealing layer 24 is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. One suitable thermoplastic elastomer (TPE) material for inner sealing layer 24 of dual wall co-extruded corrugated tubing 20 is a thermoplastic elastomer (TPE) material distributed under the trademark SANTOPRENE® by Advanced Elastomer Products, L. P. in Akron, Ohio. Inner sealing layer 24 provides a sealing surface for attachment of dual wall co-extruded corrugated tubing 20 to other components. To form dual wall co-extruded corrugated tubing 20, outer protective layer 22 and inner sealing layer 24 are preferably co-extruded in a single operation to form dual wall co-extruded corrugated tubing 20 as an integral one-piece component . Referring now to Figures 4 through 6, which illustrate a side elevational view, shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a second preferred embodiment of the present invention, a first exploded cross-sectional view of the second preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 4 taken from circle 5 - 5 in Figure 4 and a second exploded cross-sectional view of the second preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 4 taken from circle 6 - 6 in Figure 4, respectively, dual wall co-extruded corrugated tubing, generally identified by reference number 30, preferably includes outer protective layer 32 which is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and inner sealing layer 34 which is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) . Outer protective layer 32 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 30 and inner sealing layer 34 provides a sealing surface for dual wall co-extruded corrugated tubing 30. Dual wall co-extruded corrugated tubing 30 is preferably fabricated as an integral one-piece component in a single operation and replaces prior art single layer extruded corrugated tubing fabricated from, for example, polypropylene, nylon or a thermoplastic elastomer (TPE) material, as well as extruded corrugated tubing assemblies which are fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one (1) or more end seal(s) which are fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE), and the one or more end seal(s) are attached to one or both ends of the length of extruded corrugated tubing in a separate operation. Dual wall co-extruded corrugated tubing 30 in accordance with the present invention is anticipated to be used in major household appliances, such as dishwashers and washing machines, as well as in automotive, plumbing and other applications. The inside diameter of dual wall co-extruded corrugated tubing 30 is preferably in the range of one quarter (1/4) of an inch to four (4) inches and more preferably is in the range of three eighths (3/8) of an inch to one and one half (1 1/2) inches. In the preferred embodiment of dual wall co-extruded corrugated tubing 30 shown in Figures 4 ■ through 6, outer protective layer 32 is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. Outer protective layer 32 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 30. Inner sealing layer 34 is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. One suitable thermoplastic elastomer (TPE) material for inner sealing layer 34 of dual wall co-extruded corrugated tubing 30 is a thermoplastic elastomer (TPE) material distributed under the trademark SANTOPRENE® by Advanced Elastomer Products, L. P. in Akron, Ohio. Inner sealing layer 34 provides a sealing surface for attachment of dual wall co-extruded corrugated tubing 30 to other components. To form dual wall co-extruded corrugated tubing 30, outer protective layer .32 and inner sealing layer 34 are preferably co-extruded in a single operation to form dual wall co-extruded corrugated tubing 30 as an integral one-piece component . Referring now to Figures 7 and 8, which illustrate a side elevational view, shown partly in cross-section, of dual wall co-extruded corrugated tubing in accordance with a third preferred embodiment of the present invention and an exploded cross-sectional view of the third preferred embodiment of dual wall co-extruded corrugated tubing shown in Figure 7 taken from circle 8 - 8 in Figure 7, respectively, dual wall co-extruded corrugated tubing, generally identified by reference number 40, preferably includes outer protective layer 42 which is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and inner sealing layer 44 which is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) . Outer protective layer 42 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 40 and inner sealing layer 44 provides a sealing surface for dual wall co-extruded corrugated tubing 40. Dual wall co-extruded corrugated tubing 40 is preferably fabricated as an integral one-piece component in a single operation and replaces prior art single layer extruded corrugated tubing fabricated from, for example, polypropylene, nylon or a thermoplastic elastomer (TPE) material, as well as extruded corrugated tubing assemblies which are fabricated from a length of extruded corrugated tubing fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and one (1) or more end seal(s) which are fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE), and the one (1) or more end seal(s) are attached to one or both ends of the length of extruded corrugated tubing in a separate operation. Dual wall co-extruded corrugated tubing 40 in accordance with the present invention is anticipated to be used in major household appliances, such as dishwashers and washing machines, as well as in automotive, plumbing and other applications. The inside diameter of dual wall co-extruded corrugated tubing 40 is preferably in the range of one quarter (1/4) of an inch to four (4) inches and more preferably is in the range of three eighths (3/8) of an inch to one and one half (1 1/2) inches. In the preferred embodiment of dual wall co-extruded corrugated tubing 40 shown in Figures 7 and 8, outer protective layer 42 is preferably fabricated from a relatively rigid plastic material, such as polypropylene or nylon, and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. Outer protective layer 42 provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for dual wall co-extruded corrugated tubing 40. Inner sealing layer 44 is preferably fabricated from a softer, more ductile, polymeric material, such as a thermoplastic elastomer (TPE) , and preferably has a thickness in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. One suitable thermoplastic elastomer (TPE) material for inner sealing layer 44 of dual wall co-extruded corrugated tubing 40 is a thermoplastic elastomer (TPE) material distributed under the trademark SANTOPRENE® by Advanced Elastomer Products, L. P. in Akron, Ohio. Inner sealing layer 44 provides a sealing surface for attachment of dual wall co-extruded corrugated tubing 40 to other components. To form dual wall co-extruded corrugated tubing 40, outer protective layer 42 and inner sealing layer 44 are preferably co-extruded in a single operation to form dual wall co-extruded corrugated tubing 40 as an integral one-piece component . Accordingly, although the present invention has been described above in detail, the same is by way of illustration and example only and is not to be taken as a limitation on the present invention. It is apparent to those having a level of ordinary skill in the relevant art that other variations and modifications in dual wall co-extruded corrugated tubing in accordance with the present invention, as described and shown herein, could be readily made using the teachings of the present invention. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims .

Claims: WHAT IS CLAIMED IS: 1. Dual wall co-extruded corrugated tubing, comprising: an outer protective layer fabricated from a relatively rigid plastic material to provide crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for said dual wall co-extruded corrugated tubing; and an inner sealing layer fabricated from a softer, more ductile, polymeric material to provide a sealing surface for said dual wall co-extruded corrugated tubing. 2. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said outer protective layer is fabricated from a polypropylene material. 3. The dual wall co-extruded corrugated tubing in accordance with claim 2, wherein said inner sealing layer is fabricated from a thermoplastic elastomer (TPE) material. 4. The dual wall co-extruded corrugated tubing in accordance with claim 3, wherein the inside diameter of said dual wall co-extruded corrugated tubing is in the range of one quarter (1/4) of an inch to four (4) inches. 5. The dual wall co-extruded corrugated tubing in accordance with claim 4, wherein the thickness of said outer protective layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 6. The dual wall co-extruded corrugated tubing in accordance with claim 5, wherein the thickness of said inner sealing layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 7. The dual wall co-extruded corrugated tubing in accordance with claim 6, wherein said dual wall co-extruded corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which are relatively flexible . 8. The dual wall co-extruded corrugated tubing in accordance with claim 7, wherein said dual wall co-extruded corrugated tubing is fabricated as an integral one-piece component in a single operation. 9. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said outer protective layer is fabricated from a nylon material. 10. The dual wall co-extruded corrugated tubing in accordance with claim 9, wherein said inner sealing layer is fabricated from a thermoplastic elastomer (TPE) material. 11. The dual wall co-extruded corrugated tubing in accordance with claim 10, wherein the inside diameter of said dual wall co-extruded corrugated tubing is in the range of one quarter (1/4) of an inch to four (4) inches. 12. The dual wall co-extruded corrugated tubing in accordance with claim 11, wherein the thickness of said outer protective layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 13. The dual wall co-extruded corrugated tubing in accordance with claim 12, wherein the thickness of said inner sealing layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 14. The dual wall co-extruded corrugated tubing in accordance with claim 13, wherein said dual wall co-extruded corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which are relatively flexible. 15. The dual wall co-extruded corrugated tubing in accordance with claim 14, wherein said dual wall co-extruded corrugated tubing is fabricated as an integral one-piece component in a single operation. 16. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said sealing inner layer is fabricated from a thermoplastic elastomer (TPE) material. 17. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein the inside diameter of said dual wall co-extruded corrugated tubing is in the range of one quarter (1/4) of an inch to four (4) inches. 18. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein the thickness of said outer protective layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 19. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein the thickness of said inner sealing layer is in the range of ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations . 20. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said dual wall co-extruded corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which are relatively flexible. 21. The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said dual wall co-extruded corrugated tubing is fabricated as an integral one-piece component in a single operation. 22. A method of forming dual wall co-extruded corrugated tubing, comprising the steps of: providing a relatively rigid plastic material; providing a softer, more ductile, polymeric material; co-extruding said relatively rigid plastic material to form an outer protective layer which provides crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for said dual wall co-extruded corrugated tubing; and at the same time co-extruding said softer, more ductile, polymeric material to form an inner sealing layer which provides a sealing surface for said dual wall co-extruded corrugated tubing. AMENDED CLAIMS [received by the International Bureau on 16 March 2001 (16.03.01); original claims 1, 4-6, 11-13, 17-19 and 22 amended; new claims 23-30 added; remaining claims unchanged (6 pages)] 1 , Dual wall co-extruded corrugated tubing, comprising: an outer protective layer having corrugations and fabricated from a relatively rigid plastic material to provide crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for said dual wall co-extruded corrugated tubing; and an inner sealing layer having corrugations and fabricated from a softer, more ductile, polymeric material to provide a sealing surface for said dual wall co- extruded corrugated tubing. 2, The dual wall co-extruded corrugated tubing in accordance with claim 1, wherein said outer protective layer is fabricated from a polypropylene material. 3, The dual wall co-extrudcd corrugated tubing in accordance with claim 2, wherein said inner sealing layer is fabricated from a thermoplastic elastomer (TPE) material. 4, The dual wall co-cxtrudcd corrugated tubing in accordance with claim 3, wherein said dual wall co-extmded corrugated tubing has an inside diameter in the range of one quarter (1/4) of an inch to four (4) inches, 5. The dual wail co-extrudcd corrugated tubing in accordance with claim 4, wherein said outer protective layer has a thickness in the range of en thousandths (0,010) of an inch to forty thousandths (0.040) of an inch in the corrugations, 6. The dual wall co-extruded corrugated tubing in accordance with claim 5, wherein said inner scaling layer has a thickness in the range of ten thousandths (0,010) of an inch to forty thousandths (0.040) of an inch in the corrugations. 7. The dual wall co-extrudcd corrugated tubing in accordance with claim 6, wherein said dual wall co-extrudcd corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which are relatively flexible. S, The dual wall co-extrudcd corrugated tubing in accordance with claim 7, wherein said dual wall co-extrudcd corrugated tubing is fabricated as an integral one- pj ' cce component in a single operation, 9. The dual wall co-extrudcd corrugated tubing in accordance with claim I, wherein said outer protective layer is fabricated from a nylon material. 10, The dual wall co-extruded corrugated tubing in accordance with claim 9, wherein said inner scaling layer is fabricated from a thermoplastic elastomer (TPE) material, 1 1, The dual wall co-cxtruded corrugated tubing in accordance with claim 10, wherein said dual wall co-extruded corrugated tubing has an inside diameter in the range of one cμiarter (1/4) of an inch to four (4) inches. 12, The dual wall co-cxtruded corrugated tubing in accordance with claim 1 1 , wherein said outer protective layer has a thickness in the range o ten thousandths (0,010) of an inch to forty thousandths (0,040) of an inch in the corrugations. 13, The dual wall co-extruded corrugated tubing in accordance with claim 12, wherein said inner sealing layer has a thickness in the range often thousandths (0.01 ) of an inch to forty thousandths (0.040) of an inch in the corrugations. 14, The dual wall co-extmded corrugated tubing in accordance with claim 13, wherein said dual wall co-extruded corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which arc relatively flexible, 15. The dual wall co-extrudcd corrugated tubing in accordance with claim 14, wherein said dual wall co-extruded corrugated tubing is fabricated as an integral one- piece component in a single operation. 16. The dual wall co-cxtruded corrugated tubing in accordance with claim 1, wherein said sealing inner layer is fabricated from a thermoplastic elastomer (TPE) material, 17. The dual wall co-extruded corrugated tubing in accordance with claim \ , wherein said dual wall co-cxtruded corrugated tubing has and inside diameter in the range of one quarter (1/4) of an inch to four (4) inches. 18. The dual wall co-extrudcd corrugated tubing in accordance with claim 1 , wherein said outer protective layer has a thickness in the range of en thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations. 19. The dual wall co-extruded corrugated tubing in accordance with claim 1 , wherein said inner scaling layer has a thickness in tlie range o ten thousandths (0.010) of an inch to forty thousandths (0.040) of an inch in the corrugations, 20. The dual wall co-extrudcd corrugated tubing in accordance with claim 1, wherein said dual wall co-extmded corrugated tubing includes "straight" portions which are relatively rigid and corrugated portions which arc relatively flexible, 21. The du al wall co-extrudcd corrugated tubing in accord auee with claim 1 , wherein said dual wall co-cxlruded corrugated tubing is fabricated as an integral one- piece component in a single operation, 22. A method of forming dual wall co-extruded corrugated tubing, comprising the steps of; providing a relatively rigid plastic material; providing a softer, more ductile, polymeric material; co-extruding said relatively rigid plastic material to form an outer protective layer having corrugations, said outer layer providing crush strength, abrasion resistance, enhanced burst strength and enhanced thermal resistance for said dual wall co-cxtruded corrugated tubing; and at the same time co-extruding said softer, more ductile, polymeric material to form an inner scaling layer having comigalions, said inner layer providing a sealing surface for said dual wall co-extrudcd corrugated tubing. 23. The dual wall co-cxtruded tubing in accordance with claim 16, wherein the outer protective layer is fabricated from a polypropylene material or a nylon material, 24. The dual wall co-eχlruded tubing in accordance with claim 23, wherein said outer protective layer and said inner layer each has a thickness in the range of 0,010 inch to 0,040 inch in the corrugations. 25. The dual wall co-extrudcd tubing in accordance with claim 23, in which said corrugated tubing, said outer layer and said inner layer each has smooth end portions at opposite ends of said tubing, 26. The dual wall co-extrudcd tubing in accordance with claim 23, in which said outer layer and said inner layer are in contact over substantially the entire length of each layer. 27. The dual wall co-extmded tubing in accordance with claim 23, in which the dimensions of said tubing and said outer and inner layers remain substantially constant during normal operating temperatures and conditions. 28. Λ method according to claim 22 in which said outer layer is a polypropylene material or a nylon material and said inner layer is a thermoplastic polyester (TPE), 2.9. A method according to claim 28 in which said outer layer has a thickness in the range of 0,010 inch to 0.040 inch in the corrugations, 30. A method according to claim 29 in which said inner layer has a thickness in the range of 0,010 inch to 0,040 inch. STATEMENT UNDER ARTICLE 19 (1) Tlie foregoing amendments to the claims were made for the purpose of clarifying the apparatus and method claims for this application, upon which all other claims depend. It is believed that the claims of the invention as now presented define over the prior it of record and that discovered as a result of the International Search Report. Care was exercised by Applicant's attorney to make certain that these amendments did not go beyond the disclosure of the mterøational application as filed. The amended claims are thought to more clearly define the elements of the present invention and are fully supported in the specification of the application as filed. Applicant's attorney further believes that the search performed by the exa iner is sufficient to cover these amended claims.

Inventors: CHENOWETH KENNETH R, HEVERLY WAYNE T, MURRAY RUSSELL A, CHENOWETH, KENNETH, R., HEVERLY, WAYNE, T., MURRAY, RUSSELL, A.
Applicants: OEM MILLER, OEM/MILLER
Application year: 2000
Main classification: F16L11
IPC codes: F16L11