WO2008005829A2

WO2008005829A2 - Flexible heatable plastic tube

Info

Publication number: WO2008005829A2
Application number: PCT/US2007/072464
Authority: WO
Inventors: Tao Nie; David Allen Bensko; Timothy Wade
Original assignee: Cooper Standard Automotive, Inc.
Priority date: 2006-06-30
Filing date: 2007-06-29
Publication date: 2008-01-10
Also published as: WO2008005829A3

Abstract

A polymeric tube that includes at least one polymeric layer having a heating mechanism associated therewith. The heating mechanism can be at least one of a conductive polymeric layer, a heating element embedded in the polymeric layer, or a heating jacket. It is contemplated that where a heating jacket is employed, it is associated with the polymeric in a manner to contribute to the heating capability of the polymeric tube construction and the fluid material conveyed therethrough. Also disclosed is at least one automotive device for conveying heated fluid to a suitable source, for example an emission control device utilizing selective catalytic reduction.

Description

FLEXIBLE HEATABLE PLASTIC TUBE

[0001] The present invention pertains to heatable hoses or lines. More particularly, the present invention pertains to heatable hoses or lines suitable for use pollution control devices, particularly those used with automotive vehicles such as selective catalytic reduction devices. The invention also pertains to selective catalytic devices and device assemblies that include such hoses or lines.

[0002] NOx emissions from vehicles with internal combustion engines are an environmental problem recognized worldwide. Several countries, including the United States, have long had regulations pending that will limit NOx emissions from vehicles. Manufacturers and researchers have put considerable effort toward meeting those regulations. In conventional gasoline-powered vehicles that use stoichiometric fuel-air mixtures, three-way catalysts have been shown to control NOx emissions. In diesel powered vehicles and vehicles with lean-burn gasoline engines, however, the exhaust is too oxygen-rich for three-way catalysts to be effective [0003] Several solutions have been posed for controlling NOx emissions from diesel powered vehicles and lean-burn gasoline engines. One set of approaches focuses on the engine. Techniques such as exhaust gas recirculation, homogenizing fuel-air mixtures, and inducing sparkless ignition can reduce NOx emissions. These techniques alone, however, will not eliminate NOx emissions. Another set of approaches remove NOx from the vehicle exhaust. These include the use of lean-burn NOx catalysts, NOx adsorber-catalysts, and selective catalytic reduction (SCR).

[0004] Selective catalytic reduction (SCR) involves using ammonia as the reductant. The

NOx can be temporarily stored in an adsorbant or ammonia can be fed continuously into the exhaust. SCR can achieve NOx reductions in excess of 90%. SCR is widely considered to be the one proven technology for NOx control and has been selected for implementation by European heavy-duty vehicle manufacturers.

[0005] In connection with SCR, the provision of ammonia is a concern. Compressed or liquid ammonia on vehicles is considered an unacceptable safety and environmental hazard. Alternatives include urea, which can be hydrolyzed as needed to form ammonia, and ammonia salts, such as carbamate, which can be decomposed to give ammonia. One such system that has gained favor with European heavy-duty vehicle manufacturers utilizes a distribution system for a 32,5% solution of urea in demneralized water. One drawback of such systems is limitations on the operational performance temperature ranges for the materials employed. Aqueous urea-based systems freeze in extremely low temperatures such as temperatures below -11 C. This poses challenges for utilizing such systems in regions that experience moderate to severe winters. At low temperatures, there is a possibility that such aqueous urea-based material can freeze in reservoirs and conduits found in the SCR system. This can compromise emission system performance.

SUMMARY

[0006] Disclosed herein is a polymeric tube that includes at least one polymeric layer having a heating mechanism associated therewith. The heating mechanism can be at least one of a conductive polymeric layer, a heating element in thermal contact with the polymeric layer, and/or a heating jacket structure. It is contemplated that where a heating jacket is employed, it is associated with the polymeric layer in a manner to contribute to the heating capability of the polymeric tube construction and the fluid material conveyed therethrough. Where a heating jacket is employed, the jacket may be configured to overlie a suitable heat generating structure. Alternately, it is contemplated that the jacket may be configured as a heat producing source as desired or required.

[0007] Also disclosed herein is a mechanism for continuously heating fluid contents within a polymeric tube that includes an inner polymeric tube configured to convey a fluid material such as aqueous urea therethrough, and outer polymeric jacket surrounding the inner polymeric tube. The outer jacket defines a conduit between the inner tube and the outer jacket. The conduit is configured to convey a suitable heating fluid and may be in communication with a heating fluid return line to convey heating fluid to a suitable reservoir for reheating and reuse. If desired or required, it is contemplated that the either the heating fluid return line or the heating fluid conduit may be in thermal communication with a suitable mechanism such as an aqueous urea storage tank prior to return to the heating liquid reservoir. While it is contemplated that the mechanism may be employed to deliver a material such as an aqueous urea solution to a device such as a selective combustion reactor, other devices include, but are not limited to, wind shield washer devices and various automotive heat exchange devices.

DESCRIPTION OF THE DRAWING

[0008] The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: [0009] FIG 1 is a perspective view a heatable polymeric tube according to an embodiment as disclosed herein; [0010] FIG 2 is a schematic view of an assembly including a heatable polymeric tube and at least one coupling member constructed from conductive polymeric material according to an embodiment as disclosed herein;

[0011] FIG 3 A is a perspective view of an additional embodiment of the heatable polymeric tube as disclosed herein;

[0012] FIG 3B is a side view of FIG 3A;

[0013] FIG 3C is a side view an alternate embodiment of the heatable polymeric tube of

FIG 3A;

[0014] FIG 4 is a detail view of an end connector suitable for use with a heatable tube according to an embodiment as disclosed herein;

[0015] FIG 5A is a partial perspective view of an additional embodiment of the heatable polymeric tube as disclosed herein.

[0016] FIG 5B is a schematic view of a recirculating liquid heating system used in combination with an automotive fluid delivery device according to an embodiment disclosed herein;

[0017] FIG 6A is a cutaway view of an additional embodiment of a heatable tube as disclosed herein;

[0018] FIG. 6B is a cross sectional view of Fig. 6A;

[0019] FIG 7A is a cutaway view of an additional embodiment of the heatable tube as disclosed herein;

[0020] FIG 7B is a detail view of Fig. 7 A with the jacket element removed; and

[0021] FIG 8 s a detail view of a heater tape element suitable for use in the various embodiments.

DETAILED DESCRIPTION

[0022] Disclosed herein is a heatable plastic polymeric tube or tube that includes at least one polymeric layer and at least one heating element associated with at least one polymeric layer.

[0023] It is contemplated that the plastic or polymeric tube disclosed herein may be employed in various devices such as those found in various automotive vehicles. One non- limiting example of a suitable device or system is one configured to deliver suitable quantities of aqueous urea solution to a device such as a selective combustion reactor used in automotive emission control devices and processes. While the plastic or polymeric tube disclosed herein is described in terms of its application to selective combustion reactors, it is to be understood that the tube construction may be employed in a variety of applications including but not limited to windshield washer devices and various automotive heat exchanger devices. [0024] In the tube as disclosed herein, the polymeric layer can be constructed from any suitable polymeric material. Typically materials of choice will be extrudable melt processible thermoplastics that exhibit heat stability and are essentially non-reactive to the materials conveyed thought the associated tube, particularly aqueous materials such as aqueous urea solutions, various washer fluid solutions and the like. The materials of choice will those capable of conveying heat to the inner channel of the associated tube or conduit at a level sufficient to prevent freezing of the conveyed aqueous material.

[0025] Where desired or required, it is contemplated that the polymeric tube can be composed of multiple polymeric layers in overlying concentric relationship to one another as desired or required. Non-limiting examples of multi-layer tube constructions include but are not limited to the constructions disclosed in U.S. Patent Number 5,524,673 to Noone and Mitchell, incorporated herein by reference.

[0026] It is contemplated that one or more layers of the plastic tube can contain melt- processible thermoplastic material. Suitable melt-processible materials include, but are not limited to polyamides and polyamide derivatives, fluoropolymers, thermoplastic elastomers, melt-processible polyesters, polyalkylenes, thermoplastic polycarbonates, thermoplastic rubbers, Examples of suitable polyamides include, but are not limited to, polyamide 6, polyamide 6,6, polyamide 11 and polyamide 12 as well as aromatic polyamides. Examples of suitable thermoplastic polyesters derived from ethylene glycol include polybutylene terephthalate, polyethylene terephthalate and polytetramethylene terephthalate. Examples of suitable thermoplastic polycarbonates components include linear, branches and aromatic polycarbonates which may optionally be compounded with materials such as ABS. Suitable amorphous thermoplastic include, but are not limited to, acrylonitrile-butadiene-styrene (ABS) and the like as well as thermoplastic alloys having the same or similar attributes. [0027] Non-limiting examples of suitable materials further include at least one of polyalkylenes and copolymers of polyalkylenes. Such materials are contemplated to include polyalkylene homopolymers as well as copolymeric materials which contain polyalkylene constituents. Such materials are broadly recognized in the art of injection molding as thermoplastic polyolefins (TPOs). In the polymeric composition and the process of the present invention, at least one alkylene monomeric unit which makes up the homopolymeric or copolymeric group, preferably, contains 2 to 6 carbon atoms in branched or unbranched monomeric units, with alkylene monomers having two, three or four carbon atoms being preferred and polymers having at least some propylene groups being most preferred. [0028] Polyolefins suitable for use in the compositions of the invention include non-polar thermoplastic, crystalline or semi-crystalline polyolefin homopolymers and copolymers. They are prepared from monoolefin monomers having 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene, isobutylene, 1-pentene and the like, with ethylene, propylene and mixtures thereof being preferred. The polyethylene can be low density, ultra-low density or high density material. The term polypropylene includes homopolymers of propylene as well as reactor copolymers of polypropylene which can contain about 1 to about 20 weight percent of ethylene or various-olefin comonomer of 4 to 16 carbon atoms, and mixtures.

[0029] Additional materials include put are not limited to thermoplastic polyamides, thermoplastic polycarbonates, and thermoplastic polyesters derived from ethylene glycol. [0030] Polyolefins suitable for use include non-polar thermoplastic, crystalline or semi-crystalline polyolefin homopolymers and copolymers. They are prepared from monoolefin monomers having 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene, isobutylene, 1-pentene and the like, with ethylene, propylene and mixtures thereof being preferred. The polyethylene can be low density, ultra-low density or high density material. The term polypropylene includes homopolymers of propylene as well as reactor copolymers of polypropylene which can contain about 1 to about 20 weight percent of ethylene or various-olefin comonomer of 4 to 16 carbon atoms, and mixtures.

[0031] It is contemplated that one of more polymeric compounds could be present in the polymeric layer 12. These materials can be present as blend, alloys and the like. As used herein, the term "alloyed relationship" and "alloy" are taken define a randomly oriented dispersion of the minor component in the major component in a manner which facilitates the orientation of the respective component relative to one another upon the application of external forces such as pressure and heat. In the alloyed relationship of the major and minor components in the composition of the present invention, the at least two respective materials exhibit little significant inter-component cross linking or bonding between one another. Rather, it is theorized that the major and minor component are present in an amorphous amalgam-like state in which the minor component resides in discrete microcells within the major component matrix. [0032] As used herein, the term "non-olefinic polymer" is broadly construed as a thermoplastic material which lacks significant olefinic qualities but can be successfully processed with polyolefins. More specifically, the non-olefinic polymeric component is at least one from the group which includes thermoplastic polyamides, thermoplastic polycarbonates, and thermoplastic polyesters derived from ethylene glycol.

[0033] As depicted in FIG 1, the tube 10 includes at least one polymeric layer 12 with at least one conductive polymeric layer 14 connected thereto. It is contemplated that the polymeric layer 12 can be composed of any suitable melt-processible polymeric material. The conductive polymeric layer 14 is composed of at least one polymer that is either inherently conductive or can contains suitable quantities of conductive material to render the associated polymeric layer material suitably conductive. Typically where conductive materials are employed, it is contemplated that the conductive materials is present in an amount sufficient to impart the desired conductive properties. Typically the conductive material content will be between 1 and 15 % by weight. Suitable conductive materials include, but are not limited to elemental carbon, stainless steel and highly conductive metals such as copper, silver, gold, nickel, silicon and mixtures thereof. The term "elemental carbon" as used herein is employed to describe and include materials commonly referred to as "carbon black". The conductive material can be present in the form of carbon fibers, powders, spheres, and the like.

[0034] The amount of conductive material contained in layer 14 is generally limited by considerations of low temperature durability and resistance to the degradative effects of the gasoline or fuel passing through the tubing. In the preferred embodiment, the thermoplastic material contains conductive material in an amount sufficient to affect conductivity and associated heating.

[0035] The conductive material can either be blended into the crystalline structure of the polymer or can be incorporated during polymerization of monomers that make up the extrudable thermoplastic material. Without being bound to any theory, it is believed that carbon-containing materials such as carbon black may be subject to incorporation during polymerization of the monomers that make up the surrounding fluoroplastic material. Materials such as stainless steel are more likely to be blended into the polymer.

[0036] It is also contemplated that the conductive material present in the polymeric materials of layer 14 can be carbon fibers may be derived from various starting materials, e.g. cellulose derivatives and special types of pitch, for example bitumen, or polyacrylonitrile. Where desired or required, the carbon fibers and/or filaments can be coated with a metal layer. Non- limiting examples of suitable metals include nickel, cobalt, copper, gold, silver and alloys of these metals with each other or with iron. The metal layer can have any suitable thickness with thicknesses from 0.05 to 10 microns being contemplated. Preferred carbon fibers have a carbon content above 80% by weight. Those fibers having a graphite-like structure and an elastic modulus above 300,000 MPa can be employed where desired or required. Metals that may be particularly advantageous in some instances include cobalt and nickel as well as cobalt-nickel, cobalt-iron, nickel-iron and cobalt-nickel-iron alloys.

[0037] The following classes of polymers, for example, are suitable for use with metalized carbon fibres: epoxide resins, polyester resins, phenol resins, aminoplastics, polyurethane resin, silicone resins, polyamides, polyimides, thermoplastic polyesters, polycarbonate and polyacrylate.

[0038] Where the inner layer is an inherently conductive polymeric material, it is contemplated that non-limiting examples of suitable materials include poly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, poly(aniline)s, poly(fluorine)s, polynaphthalenes, poly(p- phenylene sulfide), and poly(para-phenylene vinylene)s. Classically, these compounds are known as polyacetylene, polyaniline, etc. "blacks" or "melanins".

[0039] The tube may have any suitable outer diameter and inner diameter as well as suitable wall thicknesses. It is contemplated that tubes used to convey aqueous urea compositions to SCR devices will have a wall thickness suitable to maintain the structural integrity of the tube. In automotive applications with thicknesses between 0.02 and 1.0 inches are generally contemplated. It is generally contemplated that the tube 10 can have any suitable OD and BD as desired or required to convey the fluid material.

[0040] As depicted in the FIG. 1 , the heating element is configured as an inner conductive layer 14 bonded to a polymeric layer 12. It is contemplated that the tube 10 can include suitable bonding or adhesive layers (not shown) as desired or required to further facilitate bonding between the respective layers. Without being bound to any theory, it is believed that the use of a conductive layer as the heating element together with and an essentially non-conductive polymeric layer postioned outward of the conductive layer can facilitate heat transfer to the fluid material traveling through the tube 10. Without being bound to any theory, it is believed that the outer polymeric layer 12 exhibits at least some insulative character due, at least in part to some of the polymeric materials used in the outer polymeric layer 12. Heat generated as a result of current conveyed through the inner layer 14 is directed inward toward the conveyed fluid. It is also believed that in many configurations, the polymeric material of outer polymeric layer 12 will be on that exhibits electrical insulative characteristics.

[0041] It is contemplated that tubing as disclosed herein can be used together with suitable coupling members 16, 17 as depicted in FIG 2. Where desired, it is contemplated that the coupling members 16, 17 can be configured as quick connectors. Non-limiting examples of suitable quick connectors include those discussed in U.S. Patent Number 6,755, 675 the specification of which is incorporated herein by reference. Where desired or required, it is contemplated that the coupling members can be made of a suitable conductive plastic material. [0042] An alternate embodiment of the tube 10 as disclosed herein is depicted in FIG 3 A.

As depicted in FIG 3A, tube 10' is composed of at least one polymeric layer 12' with at least one heating element 18 embedded therein. The heating element 18 can be an elongated strip that is surrounded and encased by the polymeric material of layer 12'. It is also within the purview of this disclosure that the elongated strip be interposed between two different layers of a suitable multi-layer tubing structure.

[0043] The heating elements 18 can be positioned along the radius of the tube 10, structure in any orientation and/or number suitable to achieve heating in the conduit defined by the tube. Where desired or required, the heating element(s) 18 can be spaced equidistant from one another as depicted in FIG 3 A. It is also within the purview of this disclosure to position the various heating elements 18 can be positioned in a non-symmetric relationship relative to one another depending upon various conditions including, but not limited to, the location of the tubing in the automotive vehicle, heat transfer requirements and the like. Where desired or required, the heating element(s) 18 can be spirally wrapped around the tube 10. Other non- limiting examples or suitable orientations include straight longitudinal positioning as well as various other sinusoidal configurations, zigzags and the like.

[0044] The heating element(s) 18 can be composed of various conductive materials. Non- limiting examples of suitable conductive materials include nickel-plated carbon and various conductive materials as outlined previously. It is also contemplated that the material can be fiber- woven material or the like. Alternately, it is contemplated that the material could, in certain instances, be a resistance wire, etched foil, thin film polymeric construction or the like. [0045] It is contemplated that one or more heating element(s) 18 can be embedded in the tube wall. As depicted in Fig. 3 A, the tube wall has four heating elements 18 embedded in the tube wall at equal circumferential intervals. It is contemplated that the size and number of heating elements 18 embedded in layer 12 will be that sufficient to achieve sufficient heating of the transiting fluid.

[0046] The embedded element(s) 18 can be oriented in any suitable manner relative to longitudinal axis A of the tube 10, 10'. If desired or required, the embedded element(s) 18 run parallel to the longitudinal axis in a straight manner. Alternately, the embedded element(s) can be positioned in any suitable curvilinear manner. It is also within the purview of this disclosure that the embedded element(s) be embedded in a manner that wraps them spirally around the tube such as tube 10'.

[0047] The tube such as tube 10' as depicted in Fig. 3 A, 3B, and 3C can be configured with a suitable end connection to couple it to associated devices. Thus the present disclosure contemplates an assembly that includes a tube having at least on polymeric layer, at least one heating element associated with the polymeric layer and at least one end fitting attached to at least one end of the tube.

[0048] As depicted in Fig. 4, the end connection 20 can include a connector 22 in fluid- tight contact with the tube 10, 10', and a suitable electrical connection 22. The connector is configured to be in suitable electrical contact with the embedded heating element(s). Where desired or required, the assembly can include suitable thermostats, sensors, and feedback mechanisms to regulate or control the electric current flowing through the electrical connection and associated the tube 10, 10'.

[0049] It is contemplated that the amount of current traveling through the tube will be that sufficient to maintain the transiting fluid contained in the tube in a liquid state. [0050] When employed to convey aqueous urea solutions to a selective catalytic reduction apparatus, it is contemplated that the tube 10, 10' will include a first end (not shown) that can be connected to a suitable aqueous urea reservoir (not shown). The second or exit end of the tube 10, 10' can be suitably connected to a devise such as an associated selective catalytic reduction apparatus. The assembly can include suitable connection to achieve and convey electric current through the tube 10, 10', thereby achieving appropriate heating of the transiting fluid. [0051] It is contemplated that the assembly can include suitable pumps, monitors, regulators, and the like, as desired or required. It is also contemplated that the associated assembly may include a suitable reservoir or holding tank that can contain quantities of the associated fluid for recirculation and reuse. For example in systems circulating aqueous urea, it is contemplated that the assembly can include a suitable aqueous urea reservoir. Where desired or required, it is also contemplated that the assembly can include suitable heating devices to preheat the fluid prior to transit through the tube. By way of non-limiting example, it is contemplated that a material such as an aqueous urea material can be preheated in the reservoir prior to transit through the tube or tubes.

[0052] Another embodiment of the tube 110 disclosed herein is depicted in Fig. 5 A.

Tube 110 as disclosed herein can be used in a suitable device such as a catalytic reduction system utilizing urea and can include the elements depicted in Fig. 5B.

[0053] In the particular embodiment as disclosed in Fig, 5A, tube 110 can include concentric inner and outer polymeric tubes in which the inner tube 111 is configured to convey the aqueous urea solution through a conduit defined in the inner tube from a suitable storage tank 112 to the selective catalytic reduction device 114. In the embodiment as depicted in Fig. 5A, the heating element 118 is composed on an outer tube 113 positioned a spaced distance from at least a portion of the outer surface 115 of inner tube 111 in a manner that defines a channel. [0054] The outer tube 113 can be concentrically disposed around the inner tube 111.

Alternately, it is contemplated that the outer tube 113 can be non-concentrically disposed around the inner tube such that a channel is defined between the inner and outer tubes around at least a portion of the circumference of the inner tube 111.

[0055] It is contemplated that the inner tube 111 can be composed of at least one layer of a polymeric material. The polymeric materials can be those outlined previously in conjunction with the embodiment depicted in Fig. 1. The tube 111 can be composed of a single layer of polymeric material. It is also contemplated that the tubing 111 can include multiple layers of polymeric tube. Nonlimiting examples of multilayer tube constructions include, but are not limited to, the constructions disclosed in U.S. Patent No. 5,524,673 to Noone and Mitchell. The specification is incorporated herein by reference. It is also contemplated that the tube can include various other thermoplastic materials including, but not limited to, aromatic polyamides, aliphatic polyamides, polyalkylenes, thermoplastic elastomers, polyphenylene sulfites, and the like. [0056] As indicated, the inner tube 111 includes outer surface 115. It is contemplated that the outer tube 1 13 is disposed around the inner tube 111 in a manner that defines a transit conduit therearound through which a suitable heated fluid can pass. Thus, the construction of tube 110 accomplishes a tube-in-tube heating jacket. As depicted, it is contemplated that the reactant solution requiring heating is conveyed through the conduit defined by the inner tube 111. A suitable heating fluid is conveyed through the conduit defined by the outer heating jacket 113. As used herein, the fluid can be any suitable gas or liquid as desired or required. Tube 110 can be configured with suitable fittings, couplings or the like to connect the heating fluid conduit to a suitable heating fluid recirculating system (not shown). The heating fluid recirculating system can include various pumps, reservoirs and the like as necessary to convey sufficient volumes of heating fluid through the heating fluid conduit at a suitable temperature to maintain the temperature in the reactant fluid conduit at a desired temperature. [0057] The apparatus 100 as depicted in Fig. 5B is an embodiment of an integrated system that includes tube 110. The apparatus includes a reactant reservoir 112 having suitable pumps and metering devices to introduce a reactant material such as aqueous urea into the inner tube 111 of tube 110. The outer tube 113 includes connections to a suitable heating liquid reservoir 116 configured to collect and maintain suitable quantities of fluid for introduction into the conduit 113. The device can also include suitable pumps 118 and inline heaters 120 to elevate the temperature of the heating fluid to a level sufficient to heat or maintain the temperature of the transiting aqueous urea material. The heating liquid flows through conduit defined by outer tube 113 to an exit point proximate to the discharge point of the inner tube 111. It is contemplated that the heating fluid conduit can be connected to a suitable return line 122 to convey the heating fluid back to the reservoir 116 for recirculation and reuse. Where desired or required, it is contemplated that the heating fluid, upon exit from the heating fluid conduit defined by outer tube 113 can be conveyed through a suitable heat exchange coil 124 contained within aqueous urea reservoir 112 to preheat the aqueous urea material prior to introduction into the conduit defined by inner tube 111.

[0058] The tube 110 and associated apparatus can also include suitable valves and connectors as desired or required.

[0059] Where desired, the tube 110 can be connected to a suitable dosing unit 126 to regulate introduction of the transiting aqueous urea solution into the selective catalytic reduction unit 114. While not shown, it is contemplated that the dosing unit can be electronically connected to suitable command devices and the like to regulate the introduction of aqueous urea material into the unit 114. It is also contemplated that the device can include suitable sensors and other communication elements to coordinate and regulate operations of any pump contained within aqueous urea storage reservoir 112 as well as pumps and heaters associated with the heating fluid circuit. In the embodiment of a suitable catalytic reduction system as generally depicted in Fig. 5, it is contemplated that the system can include tubes of various configurations as disclosed herein.

[0060] The present disclosure also contemplates various other configurations of heated tubes. In the embodiment depicted in Fig. 6, the tube 210 includes at least one polymeric layer 212. The polymeric layer can be composed of any suitable material. In various iterations of this embodiment, the polymeric layer can be composed of a melt-processible thermoplastic that has electrically insulative characteristics when in place as the polymeric layer. It is contemplated that the material employed can be one that exhibits electrical insulative characteristics inherently or can be rendered electrically insulative by suitable additives. The material may be one that exhibits resistance to electrical current in the form of heat generation. Alternately the material may be one that possesses greater insulative characteristics but is capable of transmitting at least a portion of the heat energy generated in other regions of the tube 210 through to the interior of the tube. Suitable materials include various dielectrics such as polyamides, polyimides, polyethylenes and the like.

[0061] It is contemplated that the inner polymeric layer 212 can be composed of one or more of the materials previously discussed. Where desired or required, the inner layer can be a single layer. It is also within the purview of this disclosure to provide an inner polymeric layer 212 with multiple layers or sublayers as desired or required.

[0062] The inner polymeric layer 212 includes an inwardly oriented face 214 and an opposed outwardly oriented face 216. As in the various embodiments previously discussed, rube 210 has a heating element 218 associated with the inner polymeric layer 212 in thermal contact thereto. In the various embodiments depicted in Figs 6 - 9, the heating element 218 can be affixed to a least a portion of the outwardly oriented face 216 of the inner polymeric layer 212. As defined herein, "affixed" to the outer surface of the inner polymeric layer is taken to mean any manner in which the heating element is placed in thermal contact with the outer surface of the polymeric layer. It is contemplated that the heating element 218 can be integrated into the outer surface of the inner polymeric layer during processing. It is also contemplated that the heating element can be affixed to that outer surface by suitable adhesives or the like. These are to be considered to be non-limitative examples of heater element affixment. [0063] The heater element 218 can be any suitable device for generating and/or transmitting heat in the tube 210. Thus it is within the purview of this disclosure that various wires, foils and constructs utilizing the same can be employed in the heater element. [0064] In the embodiment as depicted in Fig. 6, the inner polymeric layer 212 can be constructed from any suitable polymeric material or materials that exhibit electrically insulative characteristics when employed in the polymeric inner tubing layer. The material or materials employed will typically be those that permit heat transmission through to the inner conduit and at least one layer can be classified as a dielectric. The inner polymeric layer 212 can be constructed of one or more polymeric material layers as desired or required.

[0065] The tube 210 as depicted in Fig. 6 also includes at least one outer jacket layer 220 that surrounds and covers the inner polymeric layer 214. The outer jacket layer 220 can be composed of any suitable polymeric jacketing material or which materials such as polyamides, polyamides blends, thermoplastic elastomers, thermoplastic polyolefins, as well as various thermosetting materials as desired or required. The material employed can be on that exhibits electrically insulative characteristics when employed in the tube construction. Suitable materials can be classified as dielectrics. The jacketing material can be one that can be applied to the tube assembly by various methods, for example various extrusion methods including coextrusion, cross head extrusion and the like. It is also contemplated that the jacket material can be applied by other suitable methods as desired or required. The jacket layer can be composed of one or mare materials that are alloyed or blended as desired or required. The jacket can also be composed of one or more layers of various polymeric materials as desired or required. [0066] The heater element 218 in the embodiment depicted in Fig. 218 is composed of at least one current conveying construct and at least one current regulating element. In the embodiment as depicted in Fig. 6, the current regulating element is a polymeric layer 220 composed of an extrudable polymeric material that exhibits positive temperature coefficient characteristics. As used herein, the term "positive temperature coefficient" is taken to mean a material that has a variable resistivity; i.e., a resistivity that changes with an external characteristic such temperature, and/or a combination of temperature and time. Non-limiting examples of such materials include PTC polymeric materials that can be employed in various embodiments, if desired or required, include materials that exhibit PTC effects that increase with temperature are contemplated herein. In such materials, the PTC is typically 45,000 ppm/C at 35° C with an increase to approximately 70,000 ppm/C at 65° C. Suitable materials may be those in which application of a constant voltage will result in rapid heating followed by equilibrium at a defined elevated temperature specified by at least one of circuit design and ambient conditions. Various polymeric systems can be effectively employed in various embodiments as disclosed herein. Suitable materials will typically have operating ranges with upper operation limit thresholds of 80° C or less. Non-limiting examples of suitable PTC polymers include materials such as various extrudable PTC polymers commercially available from a variety of DuPont Electronic Materials.

[0067] In the embodiment as depicted in Fig. 6, the at least one inner current conveying element 222 is affixed to the outer surface 213 of the inner polymeric layer 212 in any fashion. In the embodiment depicted, the current conveying element 222 is a metal wire or strip helically around the outer surface 213 of the inner polymeric layer 212 in any suitable manner. It is also contemplated that the inner current conveying element can be configured as a layer or mesh if desired or required.

[0068] The inner current conveying element 222 is affixed to the outer face 213 of the inner polymeric layer 212 by any suitable means and is interposed between the layer 212 and the current regulating element 220. Where desired or required the current regulating layer 220 can be extruded in overlying relationship to the inner polymeric layer 212 and current conveying element 222 in a manner that permits and facilitates electrical contact between the current conveying element 222 and the current regulating layer 220. In the embodiment as depicted in Fig, 6, the current regulating layer 220 is in direct bonded relationship with the current conveying element 222 and the inner polymeric layer 212. It is also considered within the purview of this disclosure to employ one of more intermediate layers or partial layers between the polymeric layer 212 and the current conveying element 222 and/or between the current conveying element 222 and the current regulating element 222 for various reasons including, but not limited to, enhancing bonding between the respective layers and elements. The material(s) employed can be any material that could enhance bonding characteristics or other properties while not unduly compromising the electrical communication between the respective elements. In the embodiment depicted, the current regulating layer 220 has an inner face 224 oriented toward the inner polymeric layer and an opposed outer face 226.

[0069] The heating element 218 as depicted in Fig. 6 also includes a second or outer current conveying element 228 in electric contact with the opposed outer face 226 of the current regulating layer 220. In the embodiment depicted, the current conveying element 228 is a metal wire or strip helically around the outer surface 226 of the current regulating layer 220 in any suitable manner. It is also contemplated that the outer current conveying element 228 can be configured as a layer or mesh if desired or required. [0070] In the configuration as depicted in Fig. 6, current introduced through one of the two current conveying elements 222, 228 is transmitted through the current regulating layer 220 to the other current conveying element acting as a ground. Transit of the current through the resistive material in the current regulating layer 220 generates heat that is transmitted through to the inner conduit. As temperature in layer 220 rises the flow of current ceases preventing further temperature elevation.

[0071] Another alternate embodiment of the heated tube disclosed herein is depicted in

Figs 7 and 8 in which the tube 310 includes at least one inner polymeric layer 312 an outer jacket 320 as previously. Heating element 318 is a suitably configured thin film heater 330. In the embodiment as depicted in Figs. 7 and 8, the thin film heater is a suitable dielectric substrate 332 with a positive buss 334, a negative buss 336 and at least one heater unit such as heater block(s) 338 postioned thereon by any suitable method. Where desired or required, heating can be accomplished by resistance or any other suitable method.

[0072] In the embodiment as depicted in Figs 7 and 8, the heater tape or thin film heater

330 is wrapped around at least a portion of the outer surface of the inner polymeric layer 312 and affixed thereto in any suitable manner. A thin film heater 330 is interposed between the inner polymeric layer 312 and the outer jacket 320 in overlying relation thereto. The inner polymeric layer and the outer jacket can be composed of materials as described previously. [0073] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Claims

What is claimed is:

1. A tube comprising: at least one polymeric layer, the polymeric layer defining a conduit; at least one heating element, the heating element associated with the polymeric layer in a manner that transfers heat to the defined conduit.

2. The tube of claim 1 wherein heating element is a polymeric layer positioned radially inward of the polymeric layer and connected thereto, the heating element including at least one of an inorganic conductive material, an inherently conductive polymeric material and mixtures thereof.

3. The tube of claim 1 wherein the heating element is an elongated member extending along the length of the tube, the elongated member embedded in the polymeric layer.

4. The tube of claims 1 to 3 wherein the elongated member is at least one of conductive fibers, resistance wire or etched foil.

5. The tube of claim 4 wherein the conductive fibers are integrated in a polymeric matrix, the polymeric matrix embedded as an elongated continuous filament in the polymeric layer.

6. The tube of claims 1 to 5 wherein the heating element is a thin film polymeric heating element positioned in thermal contact with an outer surface of the polymeric layer.

7. The tube of claims 1 to 6 further comprising an outer jacket layer, the outer jacket layer surrounding the polymeric layer.

8. The tube of claims 1 to 6 wherein the tube further comprises an outer jacket layer, the outer jacket layer surrounding the polymeric layer, wherein the heating element comprises at least on fluid channel defined in the tube by an outer surface of the inner layer and the outer jacket layer.

9. The tube of claim 8 wherein the fluid channel contains a heat transfer fluid.

10. The tube of claims 1 to 9 wherein the heater element comprises at least one of a conductive strip, a conductive film or a conductive filament in thermal contact with the polymeric layer.

11. The tube of claims 1 to 10 wherein the heater element further comprises at least one positive temperature coefficient polymeric layer in thermal contact with the conductive strip, conductive film or conductive filament.

12. The tube of claim 11 wherein the positive temperature coefficient polymeric layer has an inner surface and an outer surface, wherein the conductive strip, a conductive film or a conductive filament is in contact with the inner layer, wherein the tube further comprises at least on additional conductive element is positioned in thermal contact with the outer surface of the positive temperature coefficient polymeric layer.

13. The tube of claim 12 further comprising at least one outer jacket in overlying relationship with the positive temperature coefficient layer.

14. An automotive device comprising the tube of claims 1 to 13.

15. The automotive device of claim 14 wherein the tube is integrated in at least one of a windshield washer fluid delivery device, a selective catalytic reduction apparatus, an emissions control apparatus, or the like.

16. A device for delivering heated liquid to a location in an automotive vehicle comprising: at least one fluid reservoir; at least one conduit in fluid communication with the liquid reservoir, the conduit having an output end at a delivery location, the conduit having at least one polymeric layer and at least one heating element in thermal contact with the polymeric layer.

17. The device of claim 16 wherein the heating element comprises at least one outer jacket in spaced overlying relationship with the polymeric layer, the outer jacket defining a fluid conduit between the jacket and the polymeric layer.

18. The device of claim 17 further comprising: a fluid conduit reservoir in fluid communication with the fluid conduit; at least one heater associated with the fluid conduit; and at least one return line connected to the fluid conduit proximate to the output end of the liquid conduit in fluid communication with the fluid conduit reservoir.

19. The device of claim 18 wherein the return line includes a heat exchange element located in the liquid reservoir.