Abstract:
A low permeability hose system for providing an impermeable length of tube to transfer fluids that is flexible. The low permeability hose system generally includes a hose defining a fluid passage and an impermeable layer attached to the exterior surface of the hose. The impermeable layer is comprised of an aluminum coated heat sealable film that is impermeable to both liquids and gases. A protective layer may be attached to the impermeable layer to protect the impermeable layer from damage.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not applicable to this application. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable to this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to fluid transfer tubes and more specifically it relates to a flexible low permeability hose for providing an impermeable length of tube to transfer fluids that is flexible. 
     2. Description of the Related Art 
     Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. 
     Single layer hose and multi-layered hose (e.g. hydraulic hose) have been in use for years. The main purpose of multi-layered hose is typically to provide a flexible interior material (e.g. rubber) surrounded by a protective exterior material for abrasion resistance (e.g. multiple layers of woven wire and rubber). 
     Hoses are used to transport various types of fluids (e.g. liquid coolant, vaporized coolant, combination of liquid and vaporized coolant) from one location to another location. For example, in a spray cooling liquid thermal management system hose may be utilized to transport liquid coolant from and to a spray module or other devices within the spray cooling liquid thermal management system. 
     Single-phase liquid thermal management systems (e.g. liquid cold plates) and two-phase liquid thermal management systems (e.g. spray cooling, pool boiling, flow boiling, jet impingement cooling, falling-film cooling, parallel forced convection, curved channel cooling and capillary pumped loops) have been in use for years for thermally managing various types of heat producing devices. Spray cooling technology is being adopted today as the most efficient option for thermally managing electronic systems. U.S. Pat. No. 5,220,804 entitled High Heat Flux Evaporative Spray Cooling to Tilton et al. describes the earlier versions of spray technology, as it relates to cooling electronics. U.S. Pat. No. 6,108,201 entitled Fluid Control Apparatus and Method for Spray Cooling to Tilton et al. also describes the usage of spray technology to cool a printed circuit board. 
     The problem with conventional hose technology, particularly for liquid thermal management systems, is that the hose often times results in a percentage of the coolant (e.g. perfluorocarbon fluids) permeating through the hose resulting in a loss of the coolant. Another problem is that external air and moisture are able to permeate the coolant being transferred within the hose thereby contaminating the coolant. Hose networks comprised of a material that has low permeability (e.g. ethyl vinyl alcohol copolymer, a.k.a. EVOH) is usually relatively rigid, stiff and difficult to utilize when the hosing is implemented in thickness designed for typical system operating pressures (e.g. 20-100 psi) thereby making it impractical as a flexible hose. 
     Hence, there is a need for a hose that is flexible, resistant to various types of coolants, and impermeable to various types of coolants, gases and other substances. 
     BRIEF SUMMARY OF THE INVENTION 
     The general purpose of the present invention is to provide a low permeability hose system that has many of the advantages of the fluid transfer hoses mentioned heretofore. The invention generally relates to a fluid transfer hose which includes a hose defining a fluid passage and an impermeable layer attached to the exterior surface of the hose. The impermeable layer is comprised of an aluminum coated heat sealable film that is impermeable to both liquids and gases. A protective layer may be attached to the impermeable layer to protect the impermeable layer from damage. 
     There has thus been outlined, rather broadly, some of the features of the invention in order that the detailed description thereof may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and that will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction or to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting. 
     An object is to provide a low permeability hose system for providing an impermeable length of tube to transfer fluids that is flexible. 
     A further object is to provide a low permeability hose system that is both flexible and impermeable to fluids such as but not limited to air, gases, liquids and the like. 
     Another object is to provide a low permeability hose system that may be utilized to transfer various types of fluids including but not limited to perfluorocarbon fluids (e.g. FLOURINERT manufactured by 3M). 
     An additional object is to provide a low permeability hose system that may be utilized in various types of fluid transfer systems such as but not limited to single phase liquid thermal management systems and multi-phase liquid thermal management systems. 
     Another object is to provide a low permeability hose system that prevents the external air from permeating into the fluid being transferred. 
     Other objects and advantages of the present invention will become obvious to the reader and it is intended that these objects and advantages are within the scope of the present invention. To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is an upper perspective view of a preferred embodiment of the present invention. 
         FIG. 2   a  is a cross sectional view taken along line  2 - 2  of  FIG. 1 . 
         FIG. 2   b  is a cross sectional view of an alternative embodiment of the present invention illustrating a protective layer attached to the impermeable layer. 
         FIG. 3  is a cutaway view of the hose and an impermeable layer to be attached to the hose. 
         FIG. 4  is a cutaway view of the hose partially surrounded by the impermeable layer with the first end and the second end of the impermeable layer forming a tab structure. 
         FIG. 5  is a cutaway view of the hose and the tab structure being folded. 
         FIG. 6  is a block diagram of the low permeability hose being utilized to fluidly connect a thermal conditioning unit to a thermal management unit. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A. Overview 
     Turning now descriptively to the drawings, in which similar reference characters denote similar elements throughout the several views,  FIGS. 1 through 6  illustrate a low permeability hose system  10 , which comprises a hose  20  defining a fluid passage  22  and an impermeable layer  30  attached to the exterior surface  24  of the hose  20 . The impermeable layer  30  is comprised of an aluminum coated heat sealable film that is impermeable to both liquids and gases. A protective layer  40  may be attached to the impermeable layer  30  to protect the impermeable layer  30  from damage. 
     B. Hose 
     The hose  20  has an exterior surface  24  and an interior surface defining a fluid passage  22 . The thickness of the hose  20  may vary depending upon the technical requirements (e.g. strength, flexibility, material type, durability). The fluid passage  22  is capable of transporting both liquids (liquid coolant) and/or gases (e.g. vaporized coolant). The hose  20  and the fluid passage  22  may have various cross sectional shapes and may have various sizes capable of transferring a desired flowrate of coolant. 
     The hose  20  is comprised of at least one layer and may be comprised of multiple layers of the same or differing materials. The multiple layers may be co-extruded together forming a unitary structure or connected to one another utilizing various adhesives. 
     The hose  20  is preferably comprised of a flexible material that is compatible with a coolant utilized to thermally manage electronic devices such as but not limited to a perfluorocarbon fluid (e.g. FLOURINERT manufactured by 3M). The hose  20  is preferably comprised of a polyethylene material because of its desired fluid compatibility properties. It is further preferable that the first layer is comprised of an ethylene-octene copolymer. 
     C. Impermeable Layer 
     The impermeable layer  30  attached to said exterior surface  24  of said hose  20  as illustrated in  FIGS. 1 ,  2   a  and  2   b  of the drawings. The impermeable layer  30  prevents the escape of liquids and gases being transferred within the hose  20 . The impermeable layer  30  further prevents the entry of liquids and gases into the hose  20 . The impermeable layer  30  preferably completely surrounds said hose  20  in a sealed manner to prevent the escape (e.g. permeation) of liquids and gases from the hose  20 . 
     The impermeable layer  30  is preferably comprised of a heat sealable film. The heat sealable film is heat formed upon the hose  20  whereby the heat sealable film is contracted firmly adjacent to the exterior surface  24  of the hose  20  as shown in  FIG. 2   a  of the drawings. The impermeable layer  30  may alternatively be attached to the hose  20  by an adhesive. 
     The impermeable layer  30  is preferably comprised of an aluminized film that is impermeable to both liquids and gases. The aluminized film is preferably comprised of a first layer of polyethylene, a second layer of polyester attached to the first layer, a third layer of aluminum attached to the second layer and a fourth layer of polyethylene attached to the third layer. 
     The impermeable layer  30  has a first end  32  and a second end  34  that are preferably heat sealed together prior to folding such as with a heated pinch roller set. The first end  32  and the second end  34  may be attached to one another via other attachment systems or not attached at all. The heat sealing may be performed by any conventional heat sealing process. The first end  32  and the second end  34  are then folded forming a folded portion  36  as illustrated in  FIGS. 2   a  and  5  of the drawings. 
     There are commercial machines available that wrap film over tubing or other mandrels in a roll to roll process. Typically, a series of contoured rollers form the film around the mandrel with an extended tab portion as shown in  FIG. 4  of the drawings. When the extended tab portion is formed comprised of the first end  32  and the second end  34 , the extended tab portion may be welded together with a pair of heat pinch rollers or the like. 
     D. Protective Layer 
       FIG. 2   b  illustrates an alternative embodiment where a protective layer  40  is attached to the impermeable layer  30 . The protective layer  40  protects the impermeable layer  30  from damage and may be comprised of various materials capable of protecting the impermeable layer  30  without significantly interfering with the flexibility of the entire product. 
     E. Liquid Thermal Management System 
       FIG. 6  illustrates the exemplary usage of the low permeability hose  20  system  10  within a liquid thermal management system for thermally managing a heat producing device  16  (e.g. microprocessor, electronic device). A thermal management unit  14  is fluidly connected to the low permeability hose  20  system  10  as shown in  FIG. 6  of the drawings. The thermal management unit  14  is in thermal communication with the heat producing device  16  to thermally manage the heat producing device  16 . 
     The thermal management unit  14  may be comprised of a single-phase liquid thermal management system (e.g. liquid cold plates) or a multi-phase liquid thermal management system (e.g. spray cooling, pool boiling, flow boiling, jet impingement cooling, falling-film cooling, parallel forced convection, curved channel cooling and capillary pumped loops). Spray cooling technology is the preferred liquid thermal management system for use in the present invention. U.S. Pat. No. 5,220,804 entitled High Heat Flux Evaporative Spray Cooling to Tilton et al. and U.S. Pat. No. 6,108,201 entitled Fluid Control Apparatus and Method for Spray Cooling to Tilton et al. are hereby incorporated by reference herein. 
     A thermal conditioning unit  12  is fluidly connected to the low permeability hose  20  system  10  as further shown in  FIG. 6  of the drawings. The thermal conditioning unit  12  thermally conditions the heated exhaust coolant received from the thermal management unit  14  to lower the temperature and return the coolant back to the thermal management unit  14  for thermally managing the heat producing device  16 .  FIG. 6  illustrates the usage of two low permeability hoses  10  where one is a coolant supply line and a second is a coolant return line. The thermal conditioning unit  12  may include a heat exchanger, a pump, a filter and various other devices commonly utilized to thermally condition coolant. 
     What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims (and their equivalents) in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Any headings utilized within the description are for convenience only and have no legal or limiting effect.