Cryogenic refrigerant hose assembly with heater system for heating the cover

Abstract

A hose assembly comprising an inner hose core (12), an insulating layer (16) positioned radially outward from the inner hose core, an electrical resistance element (20) positioned radially outward from the insulating layer, and a cover layer (24) positioned radially outward from the insulating layer.

Description

[Technical Field]

[0001] This application relates generally to heated hoses, and more particularly to heated hose structures operable to prevent condensation on outer hose covers in cryogenic refrigerant applications. [Background technology]

[0002] Conventional electrically heated hoses are manufactured by wrapping an electrical conductor around an inner hose tube and then covering the wrapped inner hose tube with a sheath or outer hose cover. In many applications employing heated hoses, the inner hose tube is reinforced with a fiber braid or aramid braid, and the inner hose tube with the reinforcing braid is covered with a polyurethane sleeve or hose cover. To provide heating, the inner hose tube is wrapped with an electrically conductive wire positioned between the reinforcing layer and the outer hose cover before being enclosed within the hose cover. The electrically conductive wire typically comprises a flat copper wire, which may be either a solid ribbon or a braided strand. The electrically conductive wire functions as a resistive heating element; when the wire is electrically connected to an input power source, heat is generated by an electric current flowing through the wire. Under typical low-temperature operating conditions in typical heated hose applications, a major concern is preventing the working fluid flowing through the inner hose tube from freezing due to the cold external environment. In such applications, heat conduction is conducted inward from the conductive wire to the inner hose tube, thereby helping to prevent freezing of the working fluid under relatively cold ambient or exterior conditions.

[0003] In contrast, the present disclosure applies to applications of hose assemblies employing cryogenic refrigerants with temperatures below at least −50°C flowing through the inner hose tube. One major application, for example, is semiconductor chip manufacturing, where extreme heat is utilized to maintain proper flow of process gas. Chillers are utilized to help regulate the environment required for the manufacturing process using refrigerants pumped through the hose assembly. While refrigerants utilized in such conventional semiconductor chip manufacturing systems are cryogenic, typically between −50°C and −60°C, advances in semiconductor chip manufacturing may even result in the adoption of cooler refrigerants below −70°C to approximately −90°C. Applications employing cryogenic refrigerants operating at such substantially negative temperatures do not require concern about heating of the working fluid, which can occur under more normal environmental conditions. Therefore, conductive heater wires are not employed in cryogenic refrigerant applications because conventional heated hoses are not considered beneficial for such applications.

[0004] To operate at such substantially negative temperatures, conventional cryogenic refrigerant hose assemblies typically surround the inner hose tube with a suitable insulating layer, such as an aerogel-impregnated insulating material. The insulating layer helps maintain the refrigerant at the desired cryogenic temperature. However, problems arise in newer semiconductor chip manufacturing systems that operate at refrigerant temperatures reaching approximately -70°C or below. At these low refrigerant temperatures, when using conventional hose assemblies, the aerogel-impregnated insulation is insufficient to prevent significant cooling of the outer hose cover of the hose assembly. As a result, the outer temperature of the hose cover surface can cool below the ambient dew point temperature of the surrounding environment, causing condensation to form on the outer surface of the hose cover in the form of water or frost. The condensation can then leak from the hose cover onto the floor or other equipment near the hose assembly, potentially endangering personnel and damaging electronic equipment. Condensation can also occur when two or more conventional cryogenic hose assemblies are bundled together, as is common in semiconductor chip manufacturing systems. When bundled hose assemblies are exposed to cryogenic temperatures, they experience a lower surface temperature relative to each other than if the individual hose assemblies within the bundle were individually exposed only to ambient temperature. Summary of the Invention

[0005] Therefore, there exists a need in the art for a cryogenic hose assembly capable of providing a refrigerant flow, including a refrigerant having a temperature below approximately -70°C, without the formation of condensation experienced with conventional cryogenic hose assemblies. In an exemplary embodiment, the hose assembly is configured as a multi-layer structure including an inner hose core and may further include a reinforcing layer positioned radially outward of or wrapped around the inner hose core. The hose assembly further includes an insulating layer positioned radially outward of or wrapped around the inner hose core to provide insulation, which helps maintain the system refrigerant flowing within the inner hose core at a desired temperature level, the insulating layer being particularly important in maintaining the temperature of the cryogenic refrigerant fluid. The hose assembly further includes an electrical resistance element positioned radially outward of or wrapped around the insulating layer. The hose assembly further includes a cover layer, which is also positioned radially outward of the insulating layer. The electrical resistance element may be positioned between the insulating layer and the cover layer or may be positioned radially outward of the cover layer.

[0006] The electrical resistance element provides a low level of heating to the cover layer, thereby preventing the formation of condensation in the form of water or frost on the radially outer surface of the cover layer. For example, the electrical resistance element can provide a low level of heat to the cover layer sufficient to raise the temperature of the outer surface of the cover layer by approximately 5°C to 17°C, which is suitable for ensuring that the temperature of the radially outer surface of the cover layer exceeds the ambient dew point temperature in typical cryogenic refrigerant applications. The electrical resistance element may be configured as a helically wound or braided wire. Because the electrical resistance element provides a relatively low level of heating and is positioned or wound radially outward relative to the insulating layer, the insulating layer blocks heat generated by the electrical resistance element from being conducted to the inner hose core, which could otherwise lead to undesirable heating of the inner hose core. Thus, while conventional heated hose assemblies operate to heat the inner hose core and the working fluid, the heated hose assembly of the present disclosure heats the outer hose cover while preventing heat from entering the inner hose core and the refrigerant. Additionally, the heat provided to the cover layer by the electrical resistance element also allows multiple hose assemblies to be bundled together without condensation.

[0007] Accordingly, an aspect of the present invention is a hose assembly having a heater arrangement for heating a hose cover layer to inhibit condensation on a radially outer surface of the hose cover layer. In an exemplary embodiment, the hose assembly includes an inner hose core, an insulating layer positioned radially outward from the inner hose core, an electrical resistance element positioned radially outward from the insulating layer, and a cover layer positioned radially outward from the insulating layer.

[0008] In another exemplary embodiment, the hose assembly may further include a heat shield layer positioned radially between the insulating layer and the electrical resistance element. The heat shield layer is made of a heat-reflective material and operates to reflect heat, directing radiant heat from the electrical resistance element toward the cover layer while preventing heat input to the insulating layer, which could otherwise lead to undesired heating of the inner hose core. As a result, the heating efficiency of the cover layer is improved because essentially all of the heat generated by the electrical resistance element is directed to heat the cover layer.

[0009] In another exemplary embodiment, the hose assembly may further include a second heat shield layer positioned radially outward of the electrical resistance element and between the electrical resistance element and the cover layer.

[0010] In another exemplary embodiment, the hose assembly may further include a reinforcing layer positioned radially outward relative to the inner hose core, thereby increasing the pressure containing capacity of the inner hose core.

[0011] In another exemplary embodiment, the hose assembly may further include an electromagnetic interference (EMI) shielding layer positioned radially outward from the electrical resistance element. The EMI shielding layer may be used in certain applications to shield the electrical resistance element from EMI sources, thereby preventing interference with the operation of the electrical resistance element.

[0012] In another exemplary embodiment, the thermal barrier layer is spirally wrapped around the insulating layer.

[0013] In another exemplary embodiment, the thermal barrier layer comprises one or more of aluminum foil, a metal coated film, or a metallized Mylar® film.

[0014] In another exemplary embodiment, the electrical resistance element is positioned radially between the insulating layer and the cover layer.

[0015] In another exemplary embodiment, the electrical resistance element is positioned radially outward relative to the cover layer.

[0016] In another exemplary embodiment, the electrical resistance element is configured to provide a level of heat to the cover layer sufficient to increase the temperature of the radially outer surface of the cover layer by between 5°C and 17°C.

[0017] In another exemplary embodiment, the electrical resistance element is configured to provide a level of heat to the cover layer sufficient to raise the temperature of the radially outer surface of the cover layer by a sufficient amount above the ambient dew point temperature.

[0018] In another exemplary embodiment, the electrical resistance element is configured as a spiral winding that is spirally wrapped radially outwardly relative to the insulating layer.

[0019] In another exemplary embodiment, the helical winding includes at least one pair of wires oriented as 180° opposed helices.

[0020] In another exemplary embodiment, the electrical resistance element is configured as a braided wire wrapped radially outwardly relative to the insulating layer.

[0021] In another exemplary embodiment, the electrical resistive element has a nominal resistance of 0.6 to 15 Ω / m, corresponding to a desired output power of 15 to 75 W for operation in a constant voltage, low current input power system.

[0022] In another exemplary embodiment, the electrical resistive element has a nominal resistance of about 0.3 to 1.0 Ω / m, corresponding to a desired output power of 15 to 75 W for operation in a constant current, low voltage input power system.

[0023] In another exemplary embodiment, the reinforcing layer is wrapped around the inner hose core radially inwardly of the insulating layer.

[0024] In another exemplary embodiment, the reinforcing layer comprises one or more of a stainless steel braided material or aramid fibers.

[0025] In another exemplary embodiment, the EMI shielding layer is configured as a foil layer wrapped radially outwardly relative to the electrical resistive element.

[0026] In another exemplary embodiment, the EMI shielding layer is applied radially outwardly relative to the electrical resistive element and radially inwardly relative to the cover layer.

[0027] In another exemplary embodiment, the inner hose core is a tube comprising one or more of polytetrafluoroethylene (PTFE), corrugated metal, or linear low density polyethylene (LLDPE).

[0028] In another exemplary embodiment, the insulating layer comprises a PTFE-based or silica-based aerogel insulating material infused into a base matrix comprising one or more of a fiberglass, felt, or fiber matrix.

[0029] In another exemplary embodiment, the insulating layer comprises a strip of insulating material spirally wrapped radially outwardly about the inner core tube.

[0030] In another exemplary embodiment, the spirally wrapped configuration of the insulating layer is applied with a 50% overlap to provide a uniform double layer of insulating material along the longitudinal length of the inner hose core.

[0031] In another exemplary embodiment, the cover layer is an elastomer comprising one or more of silicone, thermoplastic polyurethane, or thermoplastic vulcanizate (TPV) having a flexural modulus of less than 30,000 psi and an elongation to break of greater than 300%.

[0032] In another exemplary embodiment, the hose assembly may further include a first shroud surrounding a first end of the hose assembly, the electrical resistance element including lead wires electrically connected to wires of the electrical resistance element, the lead wires extending through a passage formed through an outer wall of the first shroud for connection to an external input power source, and a set of first joining connections located inside the first shroud and electrically connecting the lead wires to the wires of the electrical resistance element.

[0033] In another exemplary embodiment, the hose assembly may further include a second shroud surrounding a second end of the hose assembly opposite the first end, and a second splice connection located inside the second shroud and electrically connecting opposing elements of the wire of the electrical resistance element to one another.

[0034] In another exemplary embodiment, the first shroud is configured as a first clamshell that attaches the hose assembly to a first hose fitting for providing fluid communication with the hose assembly.

[0035] In another exemplary embodiment, the second shroud is configured as a second clamshell that attaches the hose assembly to a second hose fitting for providing fluid communication with the hose assembly.

[0036] To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments, however, are indicative of only a few of the various ways in which the principles of the invention can be applied. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. [Brief explanation of the drawings]

[0037] [Figure 1]FIG. 1 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, illustrating different layers of the hose assembly, according to a first embodiment of the present disclosure. [Figure 2] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly, according to a second embodiment of the present disclosure. [Figure 2A] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly according to a variation of the second embodiment of the present disclosure. [Figure 3] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly, according to a third embodiment of the present disclosure. [Figure 4] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly, according to a fourth embodiment of the present disclosure. [Figure 5] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly, according to a fifth embodiment of the present disclosure. [Figure 6] FIG. 10 is a longitudinal elevation view of an exemplary heated hose assembly, partially cut away, showing different layers of the hose assembly, according to a sixth embodiment of the present disclosure. [Figure 7] 1 is a schematic diagram illustrating a first joint configuration for electrically connecting an electrical resistance element to an external power supply lead. [Figure 8] 8 is a schematic diagram showing a second configuration for joining opposing elements of an electrical resistance element internally, joining the electrical resistance element to an opposite end of the hose assembly relative to the first joining configuration of FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0038] Embodiments of the present disclosure will now be described with reference to the drawings, in which like reference numerals are used to refer to like elements throughout, and it should be understood that the drawings are not necessarily to scale.

[0039] Embodiments of the present disclosure provide improved cryogenic hose assembly configurations capable of providing a refrigerant flow, including refrigerants having temperatures below approximately −70° C. and down to −90° C. or below, without the formation of condensation experienced in conventional cryogenic hose assemblies. To prevent condensation, the hose assembly includes an electrical resistance element positioned or wrapped radially outwardly relative to the insulating layer, whereby the electrical resistance element operates to heat the outer cover layer of the hose assembly without heating the inner hose core. By heating the cover layer of the hose assembly, the radially outer surface of the cover layer is maintained at a temperature above the ambient dew point temperature, thereby preventing the formation of condensation on the outer surface of such cover layer. Thus, embodiments of the hose assembly are particularly suitable for use in advanced semiconductor chip manufacturing systems or other applications that may utilize similar cryogenic refrigerant flows.

[0040] FIG. 1 is a longitudinal elevation view, partially cut away, of an exemplary heated hose assembly 10 according to a first embodiment of the present disclosure, illustrating the different layers of the hose assembly. As used in this disclosure, the terms “inner” and “outer” generally refer to relative radial location from a central longitudinal axis (indicated by the double arrow) of the hose assembly 10. In the embodiment shown in FIG. 1 , the hose assembly 10 is configured as a multi-layer structure including an inner hose core 12 and may further include a reinforcing layer 14 wrapped around the inner hose core 12 or positioned radially outward relative to the inner hose core 12. The inner hose core 12 is the innermost component of the hose assembly, which carries a system working fluid, such as a cryogenic refrigerant material. The reinforcing layer 14 may optionally be employed to reinforce the inner hose core 12, thereby enhancing the inner hose core's ability to contain pressures, such as those experienced in a particular application.

[0041] The hose assembly 10 further includes an insulating layer 16 positioned or wrapped radially outwardly relative to the inner hose core 12 to provide insulation, thereby helping to maintain the system refrigerant flowing within the inner hose core at a desired low temperature level, which is particularly important in maintaining the temperature of the cryogenic refrigerant fluid. The hose assembly 10 also includes an electrical resistance element 20 positioned or wrapped radially outwardly relative to the insulating layer 16. The hose assembly further includes a cover layer 24, which is also positioned radially outwardly relative to the insulating layer 16. The cover layer 24 protects the reinforcing layer 14 and the inner hose core 12 from environmental conditions and abrasion. In the exemplary configuration of FIG. 1, the electrical resistance element 20 is positioned radially between the insulating layer 16 and the cover layer 24.

[0042] The electrical resistance element 20 provides a low level of heating to the cover layer 24, thereby preventing the formation of condensation in the form of water or frost on the radially outer surface of the cover layer 24. For example, the electrical resistance element may provide a low level of heat to the cover layer sufficient to raise the temperature of the radially outer surface of the cover layer 24 by approximately 5°C to 17°C, which is adequate to ensure that the temperature of the outer surface of the cover layer is above the ambient dew point temperature in a typical cryogenic refrigerant application. Because the temperature of the radially outer surface of the cover layer 24 is maintained above the ambient dew point temperature, condensation does not form on such outer surface of the cover layer. Because the electrical resistance element 20 provides a relatively low level of heating and because the resistance element 20 is positioned or wrapped radially outward relative to the insulating layer 16, the insulating layer 16 blocks the conduction of heat generated by the electrical resistance element 20 to the inner core tube 12, which could otherwise lead to undesirable heating of the inner hose core and refrigerant. Thus, while conventional heated hose assemblies operate to heat the inner hose core and working fluid, the heated hose assembly of the present disclosure heats the outer hose cover while preventing heat from entering the inner hose core and refrigerant. Additionally, the heat provided to the cover layer 24 by the electrical resistance element 20 also allows for multiple hose assemblies to be bundled together without condensation.

[0043] The inner hose core 12 may be a polytetrafluoroethylene (PTFE) tube having a minimum operating temperature reaching -70°C or below, preferably at least -90°C or below. The exact material employed may be selected as a result of any particular application and associated temperature range. Other materials that may be used for the inner hose core 12 for use in cryogenic refrigerant applications include, but are not limited to, one or more of a corrugated metal (e.g., stainless steel) core tube, linear low-density polyethylene (LLDPE), or other low-temperature compatible material. The reinforcing layer 14 may be a stainless steel braided material, although other suitable reinforcing materials may be employed as appropriate for any particular application, including aramid fiber, etc.

[0044] The insulating layer 16 may be a silica-based aerogel insulating material, typically infused into some base matrix, such as PTFE, fiberglass, or otherwise mechanically sound woven, felt, or fiber matrix, or polyester fiber mat matrix / polyethylene fiber mat matrix, as known in the art. As shown in the example illustrated in FIG. 1 , a strip of insulating material 16 is helically wrapped around the radially outer surface of the inner components of the hose assembly, including the inner core 12 and optional reinforcing layer 14, if present. The helically wrapped configuration may be applied with a 50% overlap to provide a substantially uniform double layer of insulating material along the longitudinal length of the inner hose core 12. Other materials, such as fiberglass insulating material, may be used for the insulating layer 16, as may be appropriate for a particular application.

[0045] 1, electrical resistance element 20 is configured as a spiral winding positioned radially between insulating layer 16 and cover layer 24. Electrical resistance element 20 may be at least one pair of copper, aluminum, conductive carbon fiber, special resistance alloy, or other electrical wires 21, 22 oriented in 180° opposed spirals, each of which may be plastic coated and spirally wrapped around insulating layer 16. In an exemplary embodiment, electrical resistance element 20 is uniformly applied to hose assembly 10.

[0046] Two types of input power systems are known in the art for heated hose systems, primarily including constant voltage systems and constant current systems. In the more common constant voltage systems, the voltage input is constant and the electrical resistive element is manufactured to have a predetermined nominal resistance per length, thereby achieving a desired output power for the constant voltage input. In constant current systems, the voltage input is variable, and thus the output power is not fixed based on the manufactured nominal resistance per length of the electrical heating element, but rather merely an adjustable voltage level based on the resistance per length of the resistive heating element, thereby achieving a constant current corresponding to the desired total output power.

[0047] Thus, potential input power systems for the hose assembly 10 include systems with a constant current and a variable voltage, and systems with a constant voltage and a variable current. For example, an electrical resistance element suitable for operation in a constant current, low voltage system may have a nominal resistance value manufactured between approximately 0.3 and 1.0 Ω / m. For example, if the electrical resistance element is manufactured to have a nominal resistance value of 0.6 Ω / m for use in a 5 A constant current system, an appropriate output power of 15 to 75 W can be achieved by adjusting the input voltage level. For example, for operation in a constant voltage, low current system, the electrical resistance element may have a nominal resistance value manufactured between approximately 0.6 and 15 Ω / m for a given constant input voltage, which corresponds to an equivalent desired output power of 15 to 75 W, depending on the voltage level of the constant voltage power supply. The following table shows exemplary characteristic parameters of an electrical resistance element, the matching electrical operating parameters (voltage and current), and the calculated total output power over the range of 15 to 75 W. It should be noted that the examples in the table below are not limiting and the various parameters may be adjusted as appropriate for any particular application.

[0048] [Table 1]

[0049] [Table 2]

[0050] The cover layer 24 may be a low temperature elastomer including one or more of silicone, thermoplastic polyurethane, or thermoplastic vulcanizate (TPV) having a flexural modulus of less than 30,000 psi and an elongation to break of greater than 300%. Other materials may be used for the cover layer 24 as may be suitable for a given application.

[0051] As previously mentioned, the heat level provided by the electrical resistance element 20 is set at a level sufficient to heat the cover layer 24 sufficiently to prevent condensation, but this level is typically low enough that the insulating layer 16 blocks heat input to the inner hose core 12. In certain circumstances, it may be necessary to operate the electrical resistance element at a level where it is desirable to provide additional thermal protection to the inner hose core in addition to a typical insulating layer.

[0052] FIG. 2 is a longitudinal elevation view, partially cut away, of an exemplary heated hose assembly according to a second embodiment of the present disclosure, illustrating the different layers of the hose assembly. The hose assembly provides additional thermal protection to the inner hose core and enhanced heating to the outer cover layer to prevent condensation. The embodiment of FIG. 2 is a variation of the embodiment of FIG. 1, and thus, like components are labeled with like reference numerals. In the example of FIG. 2, the hose assembly 10 may further include a heat shield layer 18 positioned radially between the insulating layer 16 and the electrical resistance element 20, thereby providing further thermal protection to the inner hose core 12.

[0053] The heat-shielding layer 18 is made of a heat-reflective material and acts to reflect and direct radiant heat from the electrical resistance element toward the cover layer while preventing heat input to the insulating layer. Otherwise, heat input could lead to undesired heating of the inner hose core 12 and the refrigerant. This results in improved heating efficiency for the cover layer, since essentially all of the heat generated by the electrical resistance element is directed to heat the cover layer. Additionally, the heat-shielding layer 18 acts to better distribute the energy of the heater wire of the electrical resistance element 20 across the entire inner surface of the cover 24, thereby preventing additional condensation that could otherwise form between the electrical resistance element wire and the hose surface. Therefore, the heat-shielding layer 18 better distributes heat and prevents condensation from forming under the low operating temperature energy conditions of the electrical resistance element. The heat-shielding layer 18 may be a spiral aluminum foil wrapped around the insulating layer 16 or may be aluminum foil positioned radially outward relative to the insulating layer 16. Other materials may be used for the thermal barrier layer 18 as may be appropriate for a particular application, such as, but not limited to, one or more of a metal coated film, metallized Mylar® or other impermeable film.

[0054] FIG. 2A is a longitudinal elevation view, partially cut away, of an exemplary heated hose assembly according to a variation of the second embodiment of FIG. 2, illustrating the different layers of the hose assembly. In the variation of FIG. 2A, heat shield layers are positioned both radially inward and radially outward of the electrical resistance element. For example, FIG. 2A illustrates a first heat shield layer 18a positioned radially inward of the electrical resistance element 20 and a second heat shield layer 18b positioned radially outward of the electrical resistance element 20, between the electrical resistance element and the cover layer. Sandwiching the electrical resistance element between two heat shield layers improves the effectiveness of heat dispersion of the heat generated by the electrical resistance element, thereby providing better heat dispersion to the cover layer.

[0055] 3-6 illustrate additional variations of the embodiment of FIGS. 1 and 2 of the heated hose assembly 10. For purposes of brevity, not every possible combination of individual features is shown in the figures, but it should be understood that the various individual features may be mixed and matched in any combination of one or more of such variations that may be suitable for any particular application.

[0056] As one potential variation, the electrical resistance element may be configured as a braided wire 20a instead of a helical winding 20, as shown in FIG. 3, for example. The braided wire 20a is further shown in FIG. 4 used in combination with a thermal barrier layer 18. In the above example, the electrical resistance element 20 / 20a is specifically positioned radially inward relative to the cover layer 24, while positioned radially outward relative to the insulating layer 16. In another exemplary embodiment, the electrical resistance element may be positioned radially outward relative to or around the outer surface of the cover layer 24. For example, FIG. 5 illustrates the use of an outer braided electrical resistance element 20a wound radially outward relative to the cover layer 24. As noted above, individual features may be mixed and matched as may be suitable for a given application. For example, while FIG. 5 shows the outer braided electrical resistance element 20a used in combination with a thermal barrier layer 18, in another example, the thermal barrier layer may be omitted. Additionally, an electrical resistance element configured as a winding may also be applied radially outwardly to the periphery or outer surface of the radially outer surface of the cover layer.

[0057] In another exemplary embodiment, the hose assembly may further include an electromagnetic interference (EMI) shielding layer positioned radially outward from the electrical resistance element. The EMI shielding layer may be used in certain applications to shield the electrical resistance element from EMI sources, thereby preventing interference with the operation of the electrical resistance element and preventing any EMI generated by the electrical resistance element from interfering with the operation of nearby processing equipment. The EMI shielding layer may be configured as a foil layer wrapped around or applied radially outward from the electrical resistance element. For example, FIG. 6 illustrates the use of an EMI shielding layer 28 applied radially outward from the electrical resistance element 20 and radially inward from the cover layer 24. As noted in connection with other features, the EMI shielding layer may be used or mixed and matched with other variations, such as a braided electrical resistance element 20a, with or without a thermal shielding layer 18, or combinations of other features.

[0058] FIG. 7 is a schematic diagram illustrating a first configuration for joining the electrical resistance element 20 (or 20a) to an external power supply lead. The hose assembly 10 may further include a first shroud 32 surrounding a first end 30 of the hose assembly 10. The first shroud 32 may be configured as a clamshell element that attaches the hose assembly 10 to a first hose fitting 34 for fluid communication with the hose assembly 10. The electrical resistance element 20 further includes electrical leads 36 and 37 electrically connected to an external or remote input power source (not shown), the electrical leads 36 and 37 passing through or otherwise extending through a passage formed through the outer wall of the first shroud 32. The electrical leads 36 and 37 from the input power source are electrically connected to the helical wires 21 and 22 of the electrical resistance element 20 at a pair of first joining connections 38 and 39 located inside the first shroud 32. It should be noted that although the bond is shown in connection with a spiral wire configuration of the electrical resistive element, an equivalent bond configuration may be employed in connection with a braided wire configuration of the electrical resistive element.

[0059] FIG. 8 is a schematic diagram illustrating a second configuration for internally joining opposing elements of the electrical resistance element 20 (or 20a) to an opposite end of the hose assembly relative to the first joining configuration of FIG. 7 . The second joining configuration corresponds to internally connecting the spiral wires 21 and 22 of the electrical resistance element 20 to each other at a second end of the hose assembly opposite the first end of the hose assembly to which power is supplied. As shown in FIG. 8 , the hose assembly 10 includes a second shroud 42 that surrounds the second end 40 of the hose assembly 10. The second shroud 42 may also be configured as a clamshell element that attaches the hose assembly 10 to a second hose fitting 44 for fluid communication with the hose assembly 10. In the second joining configuration, the spiral wires 21 and 22 of the electrical resistance element 20 are joined to each other at a second joining connection 48 located inside the second shroud 42. As with the previously described joint configuration in FIG. 7, with respect to the internal joint in FIG. 8, it should be noted that although the joint is shown in relation to a spiral wire configuration of the electrical resistance element, an equivalent joint configuration may be employed in relation to a braided wire configuration of the electrical resistance element.

[0060] While the present invention has been illustrated and described with respect to one or more specific embodiments, it will be apparent that equivalent variations and modifications will occur to those skilled in the art upon reading and understanding this specification and the accompanying drawings. In particular, with respect to the various functions performed by the above-described elements (components, assemblies, devices, compositions, etc.), the terms used in describing such elements (including references to "means") are intended, unless expressly stated otherwise, to correspond to any element that performs the specified function of the described element (i.e., is functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs that function in the exemplary embodiments of the invention shown herein. In addition, while a particular feature of the invention may be described above with respect to only one or more of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, as may be desirable and advantageous in any given or particular application.

Claims

1. 1. A hose assembly comprising: an inner hose core; an insulating layer positioned radially outwardly relative to the inner hose core; an electrical resistance element positioned radially outward relative to the insulating layer; a cover layer positioned radially outwardly relative to the insulating layer; A hose assembly comprising:

2. 2. The hose assembly of claim 1, further comprising a heat shield layer positioned radially between the insulating layer and the electrical resistance element, the heat shield layer being made of a heat reflective material and operating to reflect and direct radiant heat from the electrical resistance element toward the cover layer while preventing heat input to the insulating layer.

3. The hose assembly of claim 2 , wherein the thermal barrier layer is spirally wrapped around the insulating layer.

4. 4. The hose assembly of claim 2 or 3, wherein the heat barrier layer comprises one or more of an aluminum foil, a metal coated film, or a metallized Mylar® film.

5. 5. The hose assembly of claim 2, further comprising a second heat shield layer positioned radially outward of the electrical resistance element and between the electrical resistance element and the cover layer.

6. 6. A hose assembly according to claim 1, wherein the electrical resistance element is positioned radially between the insulating layer and the cover layer.

7. 6. A hose assembly according to claim 1, wherein the electrical resistance element is positioned radially outward relative to the cover layer.

8. 8. The hose assembly of claim 1, wherein the electrical resistance element is configured to provide a level of heat to the cover layer sufficient to increase the temperature of the radially outer surface of the cover layer by between 5°C and 17°C.

9. 9. The hose assembly of claim 1, wherein the electrical resistance element is configured to provide a level of heat to the cover layer sufficient to raise the temperature of the radially outer surface of the cover layer by a sufficient amount above an ambient dew point temperature.

10. 10. A hose assembly according to claim 1, wherein the electrical resistance element is configured as a spiral winding wound spirally radially outwardly of the insulating layer.

11. The hose assembly of claim 10, wherein the helical winding includes at least one pair of wires oriented in 180° opposed helices.

12. 10. A hose assembly according to any one of claims 1 to 9, wherein the electrical resistance element is configured as a braided wire wound radially outwardly relative to the insulating layer.

13. 13. The hose assembly of any one of claims 1 to 12, wherein the electrical resistive element has a nominal resistance of 0.6 to 15 ohms / meter, corresponding to a desired output power of 15 to 75 watts for operation in a constant voltage, low current input power system.

14. 13. The hose assembly of any one of claims 1 to 12, wherein the electrical resistive element has a nominal resistance of about 0.3 to 1.0 ohm / m, corresponding to a desired output power of 15 to 75 watts for operation in a constant current, low voltage input power system.

15. 15. The hose assembly of claim 1, further comprising a reinforcing layer positioned radially outwardly relative to the inner hose core.

16. The hose assembly of claim 15, wherein the reinforcing layer is wrapped around the inner hose core radially inwardly of the insulating layer.

17. 17. A hose assembly according to claim 15 or 16, wherein the reinforcing layer comprises one or more of a stainless steel braided material or aramid fibers.

18. 18. The hose assembly of claim 1, further comprising an electromagnetic interference (EMI) shielding layer positioned externally relative to the electrical resistance element.

19. 20. The hose assembly of claim 18, wherein the EMI shielding layer is configured as a foil layer wrapped radially outwardly relative to the electrical resistive element.

20. 20. The hose assembly of claim 18 or 19, wherein the EMI shielding layer is applied radially outwardly relative to the electrical resistive element and radially inwardly relative to the cover layer.

21. 21. The hose assembly of any one of claims 1 to 20, wherein the inner hose core is a tube comprising one or more of polytetrafluoroethylene (PTFE), corrugated metal, or linear low density polyethylene (LLDPE).

22. 22. The hose assembly of any one of claims 1 to 21, wherein the insulating layer comprises a PTFE-based or silica-based aerogel insulating material infused into a base matrix comprising one or more of a fiberglass, felt, or fiber matrix.

23. 23. A hose assembly according to any preceding claim, wherein the insulating layer comprises a strip of insulating material spirally wrapped radially outwardly about the inner core tube.

24. 24. The hose assembly of claim 23, wherein the spirally wrapped configuration of the insulating layer is applied with a 50% overlap to provide a uniform double layer of insulating material along the longitudinal length of the inner hose core.

25. 25. The hose assembly of any one of claims 1 to 24, wherein the cover layer is an elastomer comprising one or more of silicone, thermoplastic polyurethane, or thermoplastic vulcanizate (TPV) having a flexural modulus of less than 30,000 psi and an elongation to break of greater than 300%.

26. a first shroud surrounding a first end of the hose assembly, the electrical resistance element includes a lead wire electrically connected to a wire of the electrical resistance element, the lead wire extending through a passage formed through an outer wall of the first shroud for connection to an external input power source; a first shroud; a pair of first splice connections located inside the first shroud and electrically connecting the lead wires to the wires of the electrical resistance element; 26. The hose assembly of any one of claims 1 to 25, further comprising:

27. a second shroud surrounding a second end of the hose assembly opposite the first end; a second splice connection located inside the second shroud and electrically connecting opposing elements of the wire of the electrical resistance element to each other; 27. The hose assembly of claim 26, further comprising:

28. 28. The hose assembly of claim 26 or 27, wherein the first shroud is configured as a first clamshell that attaches the hose assembly to a first hose fitting for providing fluid communication with the hose assembly.

29. 29. The hose assembly of claim 27 or 28, wherein the second shroud is configured as a second clamshell that attaches the hose assembly to a second hose fitting for providing fluid communication with the hose assembly.

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