Patent Publication Number: US-2007095467-A1

Title: Method for joining tubular bodies with a connector

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to methods for coupling two or more components and, in particular, to a method for coupling plastic coated metal tubing using connectors and a thermoplastic bonding material to form a fluid tight, pressurized joint.  
      2. Discussion of Related Art  
      Motor vehicles may include various fluid handling systems, such as, but not limited to, fuel systems, power steering systems, heating and cooling systems, and hydraulic braking systems. These fluid handling systems may require the attachment of various tubular bodies, connectors and other components to create robust seals and fluid tight, pressurized joints for fluid handling.  
      A variety of methods are known for joining components of a fluid handling system. Ashland, Inc. has previously developed a process under the registered trademark “EMABOND” using induction welding to join two thermoplastic bodies. This process uses a bonding agent or resin disposed between the thermoplastic bodies and having metallic particles. A. Raymond Corp. has developed a process reflected in Published PCT patent application WO 01/21996 in which a tubular body is joined to a plastic connector using a meltable adhesive. Each of these methods, while satisfactory for its intended purpose, is used to join single material components (e.g., a thermoplastic body to another thermoplastic body or to a metallic body).  
      The inventors herein have recognized the benefits of using multi-layer tubing, and specifically plastic coated metal tubing, in fluid handling systems. See commonly assigned U.S. patent application Ser. No. 11/042,014 filed Jan. 25, 2005, the entire disclosure of which is incorporated herein by reference. The inventors have further recognized a need for a method for coupling components in a fluid handling system in which multi layer tubing and connectors are used.  
     SUMMARY OF THE INVENTION  
      The present invention relates to a method for coupling components of a fluid handling system.  
      A method in accordance with the present invention includes the step of providing a first component, the first component comprising a tubular body having a metallic layer and a polymeric layer. The method also includes the step of providing a second component, the second component comprising a connector. The connector defines a first port. The method also includes the steps of providing a thermoplastic material proximate the first port of the connector and positioning one of the first and second components relative to another of the first and second components such that the tubular body of the first component is proximate the first port of the connector. Finally, the method includes the step of energizing a first conductor to deform the first thermoplastic material and form a bond between the first and second components.  
      A method in accordance with the present invention has significant advantages relative to conventional manufacturing methods for coupling fluid system components. The method provides an efficient process for coupling plastic coated metal tubing and connectors while creating a fluid tight, pressurized joint.  
      These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view illustrating one embodiment of a fluid coupling formed in accordance with the present invention.  
       FIG. 2  is a cross-sectional view illustrating another embodiment of a fluid coupling formed in accordance with the present invention.  
       FIG. 3  is a cross-sectional view illustrating yet another embodiment of a fluid coupling formed in accordance with the present invention.  
       FIG. 4  is a cross-sectional view illustrating yet another embodiment of a fluid coupling formed in accordance with the present invention.  
       FIG. 5  is a flow chart illustrating a method in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION  
      Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,  FIG. 1  illustrates one embodiment of a fluid coupling  10  formed in accordance with the present invention. Fluid coupling  10  may be provided to transport fluid in a fluid handling system of a motor vehicle. Fluid handling systems constructed in accordance with the present invention may be particularly adapted for use in an automobile or light truck, but it should be understood that the inventive method described herein could be used for a variety of fluid handling systems for vehicular and non-vehicular applications. Coupling  10  includes at least two components  12 ,  14  and a thermoplastic bonding material  16 .  
      Component  12  may comprise relatively rigid tubing for use in fluid handling. Component  12  defines a fluid passageway  18  in which fuel or another fluid may be stored and/or through which fuel or another fluid may be transported. Component  12  includes a metallic layer  20  and a polymeric layer  22 . In the illustrated embodiment, metallic layer  20  is disposed inwardly of polymeric layer  22 . It should be understood that additional laminate layers may be formed between layers  20 ,  22  and that either of layers  20 ,  22  may include a plurality of sublayers without departing from the spirit of the present invention.  
      Layer  20  may comprise steel. In a preferred embodiment layer  20  comprises aluminum. Layer  22  is polymeric and may comprise a plastic and, in particular, a thermoplastic. Layer  22  may or may not include a metallic or carbon or other non-metallic filler. In a preferred embodiment, layer  22  comprises nylon. Nylon refers to a family of polyamides generally characterized by the presence of the amide group, —CONH. In a preferred embodiment, the nylon is of a type known as nylon 12. It should be understood, however, that the type of nylon may vary and may be conductive (e.g., through the addition of carbon black) or non-conductive. Layer  22  may be pre-bonded to the layer  20  and may be extruded over the layer  20 . In one constructed embodiment, the component is formed from nylon coated aluminum tubing sold under the registered trademark “HYCOT” by Hydro Aluminum Hycot USA, Inc. The aluminum layer of the tubing has a thickness of about 0.1 to about 1.2 mm. The nylon layer of the tubing has a thickness of between about 80 and about 500 microns and may measure about 150 microns.  
      Component  14  comprises a connector for connecting other components (e.g., for connecting component  12  to another component  12  or a different component). Component  14  may be made from a polymer such as a plastic. Component  14  defines at least one opening or port  24 , but typically defines multiple ports used to connect multiple fluid conduits. In one embodiment of the invention, component  14  comprises a tee connectors having three separate ports  24 . Component  14  may define one or more fluid passageways  26  extending between ports  24 .  
      Thermoplastic bonding material  16  is provided to join components  12 ,  14 . Material  16  may comprise a polyamide such as nylon or a partially aromatic polyamide. It should be understood, however, that other conventional bonding materials may be used. Material  16  is provided proximate a port  24  of component  14  where component  12  is to be joined to component  14 . In the illustrated embodiment, one end of component  12  is disposed within one end of component  14  defining port  24  and material  16  is disposed on an inner surface of component  14  between component  14  and layer  22  of component  12 . Material  16  may be relatively rigid and formed in a predefined shape and positioned within or around one end of connector  14  defining port  24 . Alternatively, material  16  may be injected molded with connector  14  as connector  14  is formed.  
      Referring now to  FIG. 2 , an alternative embodiment of a fluid coupling  110  in accordance with the present invention is illustrated. Coupling  110  is substantially similar to coupling  10 , but includes a component  112  having a metallic layer  120  disposed outwardly of the polymeric layer  122 . In this embodiment, one end of component  14  defining a port  24  is inserted into one end of component  112  and the thermoplastic material is disposed on an outer surface of component  14  between component  14  and layer  122  of component  112 .  
      Referring now to  FIG. 3 , another alternative embodiment of a fluid coupling  210  in accordance with the present invention is illustrated. Coupling  210  is substantially similar to couplings  10 ,  110 , but also differs in several respects. Coupling  210  includes a component  212  having a polymeric layer  222  disposed inwardly and outwardly of metallic layer  220 . Polymeric layer  222  may also cover an end face  228  of metallic layer  220 . Component  214  defines a recess  230  in one end face of component  214 . Recess  230  is disposed between the radially inner and outer surfaces of component  214 . Thermoplastic material  16  is disposed within recess  230  and, upon insertion of component  212  within recess  230  of component  214 , is disposed between each of the walls of recess  230  and the polymeric layer  222  of component  212 .  
      Referring now to  FIG. 4 , another alternative embodiment of a fluid coupling  310  in accordance with the present invention is illustrated. Coupling  310  is substantially similar to couplings  10 ,  110 ,  210 , but also differs in several respects. Coupling  310  includes a component  312  having a polymeric layer  322  disposed inwardly and outwardly of metallic layer  320 . Polymeric layer  322  may also cover an end face  328  of metallic layer  320 . Component  312  further defines a recess  332  in end face  328 . Recess  332  is disposed between the radially inner and outer surfaces of component  312 . Thermoplastic material  16  is disposed within recess  332  and, upon insertion of one end of component  14  within recess  332  of component  312 , material  16  is disposed between component  14  and the polymeric layer  322  covering each of the walls of recess  332 .  
      Referring now to  FIG. 5 , a method of coupling components of a fluid handling system in accordance with the present invention will be described. The inventive method may begin with the step  400  of providing a component, such as component  12 , with a tubular body and having a metallic layer and a polymeric layer. The method may continue with the step  402  of providing another component, such as component  14 , comprising a connector that defines a port.  
      The method may continue with the step  404  of providing a thermoplastic material  16  proximate the port of the connector. Step  404  may include several substeps. In one embodiment of the invention step  404  may include the substeps  406 ,  408  of forming material  16  into a predefined shape and positioning material  16  relative to the port of the connector. The predefined shape may be complementary to the shape of the port (e.g., the inner and/or outer surface of the connector) and/or may be designed to enable secure fastening of material  16  to the connector. In an alternative embodiment, step  404  may include the substep  410  of injecting material  16  into a predefined position relative to the port of the connector.  
      The method may continue with the step  412  of positioning one of the components relative to another of the components such that the tubular body of plastic coated metal component is proximate the port of the connector. Referring to  FIG. 1 , in accordance with one embodiment of the invention, step  412  may include the substep  414  of inserting one end of component  12  into port  24  of connector  14 . Referring to  FIG. 2 , in accordance with another embodiment of the invention, step  412  may include the substep  416  of inserting port  24  of connector  14  into one end of the tubular body of component  112 . Referring to  FIGS. 3-4 , in accordance with additional embodiments of the invention, step  412  may include the substep  418  of inserting one end of component  212  into a recess  230  formed in one end of component  214  between the radially inner and outer surfaces of component  214  or inserting one end of component  14  into a recess  332  formed in one end of component  312  between the radially inner and outer surfaces of component  312 .  
      Referring again to  FIG. 5 , the inventive method may include the step of  420  of applying a clamping load to the components to be joined. The load may be applied using any of a variety of conventional tools and/or methods known in the art. The load may also be applied at multiple locations along the components.  
      The inventive method may finally include the step  422  of energizing a conductor to deform material  16  and form a bond between the components. The conductor may, for example, comprise a coil through which current is fed from a power source. The inventive method thus employs a form of induction welding. The inventors herein have recognized that the resulting electromagnetic field providing inductive energy to the metallic layer of the plastic coated metal component will result in heat transfer from the metallic layer to the polymeric layer and the thermoplastic material  16  and, at sufficient levels, will result in deformation of the polymeric layer and/or material  16  through melting to form a bond between the components. The resulting bond has significant strength. Further, the bond forms a hermetic seal such that fluid handling components may have fluid inlets and outlets sealingly coupled as shown in  FIGS. 1-4 . Referring again to  FIG. 5 , step  422  may be easily repeated one or more times to insure a proper hermetic seal is formed.  
      The inventive method may be used to form a coupling between two components. In accordance with one aspect of the invention, however, the inventive method may be used to couple additional components. For example, the method may be used co couple multiple plastic coated metal tubes using a connector. The method may therefore continue with the step  424  of providing another component comprising a tubular body and having a metallic layer and a polymeric layer. The method may further continue with the step  426  of providing additional thermoplastic material proximate another port of the connector. The material may be the same material or a different material relative to the material used to join the connector to the first plastic coated metal tube. The method may further continue with the step  428  of positioning one of the additional plastic coated metal tube component and the connector relative to the other as discussed hereinabove such that the additional plastic coated metal tube is proximate another port of the connector. Finally, the method may include the step  430  of energizing either the conductor used to connect the first plastic coated metal tube and the connector or another conductor.  FIG. 5  illustrates steps  428 ,  430  as occurring subsequent to step  422 . Step  428  alternatively may be performed prior to step  422  and steps  422 ,  430  may occur substantially simultaneously allowing the formation of multiple, fluid tight joints in a more efficient manner than was previously known. It should also be understood that, although not illustrated in  FIG. 5 , a step similar to step  420  may be performed prior to step  430  to assist in formation of the fluid coupling.  
      The method may be used to couple multiple connectors to opposite ends of a plastic coated metal tube. The method may therefore continue with the steps  432 ,  434  of providing another component comprising a connector defining a port and a thermoplastic material the port. The material may again be the same material or a different material relative to the material used to join the first connector to the plastic coated metal tube. The method may further continue with the step  436  of positioning one of the additional connector component and the plastic coated metal tube component relative to the other as discussed hereinabove such that the plastic coated metal tube is proximate the port of the newly added connector. Finally, the method may include the step  438  of energizing either the conductor used to connect the plastic coated metal tube and the first connector or another conductor. Again,  FIG. 5  illustrates steps  436 ,  438  as occurring subsequent to step  422 . Step  436  alternatively may be performed prior to step  422  and steps  422 ,  438  may occur substantially simultaneously allowing the formation of multiple, fluid tight joints in a more efficient manner than was previously known. It should also again be understood that, although not illustrated in  FIG. 5 , a step similar to step  420  may be performed prior to step  438  to assist in formation of the fluid coupling.  
      A method in accordance with the present invention has significant advantages relative to conventional manufacturing methods for coupling tubular bodies. The method provides an efficient process for coupling plastic coated metal tubing and connectors while creating fluid tight, pressurized joints. For example, multiple joints can be formed simultaneously using the inventive method and the inventive method avoids the need for brazing and other costly manufacturing processes. The inventive method also allows the formation of a strong, fluid tight joint that is capable of withstanding pressurized applications without the need for complex mechanical seals  
      While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.