Abstract:
The invention relates to an arrangement involving a screw connection for connecting two pipes. The arrangement has particular application for connecting a fuel filler pipe to a pipe that is connected to a fuel tank of a motor vehicle. At least one O-ring seal with excellent permeation resistance is clamped in between a resilient ring-shaped collar of a first pipe and an inner cone of a second pipe using a screw connection.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a structure or arrangement for connecting two pipes, and in particular, for connecting a fuel filler pipe to a fuel tank pipe of a motor vehicle.  
           [0002]    Well-known and widely used pipe connections include arrangements wherein one pipe has an external thread in the connection area that a screw cap or nut located on a second pipe screws onto.  
           [0003]    A motor vehicle usually includes a fuel tank and a conduit for introducing liquid fuel into the fuel tank, commonly referred to as a fuel filler pipe. The connection between the filler pipe and the fuel tank usually involves two pipes, one end of the filler pipe and another pipe that is welded or otherwise secured to the fuel tank. It is a well-known practice to slide a flexible filler hose or sleeve over the two adjoining pipe ends and introduce a surrounding hose clamp in order to connect the two pipes. This flexible sleeve is commonly made of rubber or other material with suitable heat resistance and weatherability. However, rubber is permeable to hydrocarbon fumes, so the rubber sleeve absorbs fuel over time, leading to unpleasant odors, and more importantly, the release of toxic hydrocarbon fumes into the surrounding atmosphere. Furthermore, a need also exists in other applications for a tight connection of two pipes that is impermeable to both gases and liquids.  
           [0004]    Therefore, an object of the invention is to provide an arrangement for a connection of two pipes that is impermeable to fluids and, as much as possible, to gases such as hydrocarbon fumes.  
           [0005]    Other objects and advantages of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing.  
         SUMMARY OF THE INVENTION  
         [0006]    The invention provides a ring seal, which can be clamped in between a flexible ring-shaped collar of one pipe and an inner cone of a second pipe by means of a screw connection. Any potential permeation of vapors or gases, in particular hydrocarbon vapors emanating from the fuel, is limited to the very small surface area of the ring seal which is in contact with the external environment.  
           [0007]    The flexible ring-shaped collar increases the impermeability of the entire arrangement. This flexibility can be achieved by designing the ring-shaped collar with two flanks that are resilient against each other.  
           [0008]    To achieve a perfect fit and protect against slipping, the front transitional area between the ring-shaped collar and the pipe provides a bearing surface for an O-ring seal.  
           [0009]    The screw connection includes a connecting nut that is held by the ring-shaped collar of one pipe and a threaded part that is located on the other pipe.  
           [0010]    In one possible embodiment, the threaded part is a plastic part that is injection-molded directly onto the pipe. In another embodiment, the threaded part is a metal part that is pressed onto the pipe. Both embodiments allow the threaded part to be easily produced and attached.  
           [0011]    To ensure a tight screw connection, the threaded part must be attached tightly. For this purpose, the threaded part is held in an interlocking manner at the pipe, in particular by means of ribs or other similar means, at the circumference of the pipe.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The only drawing, FIG. 1, shows a longitudinal cross-section through two pipes in the connection area.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    As illustrated in the figure, a pipe assembly according to this invention is generally shown at  10 . It should be appreciated that while the pipe assembly  10  is described as being particularly applicable to usage with a motor vehicle fuel tank, the pipe assembly is may be used in any suitable application. The pipe assembly  10  includes a first pipe  1  and a second pipe  2  in fluid communication with the first pipe  1 . Both pipes  1 ,  2  are made of metal, preferable stainless steel, whereby one pipe (pipe  2  is shown on the left side of FIG. 1) is welded or otherwise secured to the fuel tank (not illustrated), and the other pipe (pipe  1 , located on the right side of FIG. 1) provides the connection to a fuel filler nozzle (also not illustrated). Pipes  1 ,  2  have nearly identical inner and outer diameters as well as wall thicknesses. In the illustrated embodiment, pipe  1  is equipped with a convoluted section  1   a  near its end for improved flexibility, to allow for easier handling when connecting the two pipes  1 ,  2 .  
         [0014]    The end segments  1   d ,  2   d  of the two pipes  1 ,  2 , which form the connection area, have a special design. Pipe  1  has a flexible ring-shaped bead or collar  1   b , which surrounds a portion of an end segment  1   d . The collar  1   b  has two sides or flanks  1   e  and  1   f . Each flank  1   e ,  1   f  has rounded sections, which extend from pipe  1 . The flanks  1   e ,  1   f  are generally parallel to and spaced apart from each other. The flanks  1   e ,  1   f  are interconnected by a spring portion  1   g , which allows one of the flanks  1   e ,  1   f  to be elastically displacement relative to the other of the flanks  1   e ,  1   f . The two flanks are designed and located at such a distance from one another so that the ring-shaped collar  1   b  is elastic and flexible in the axial direction. The rounded section in the transitional area of the front flank of ring-shaped collar  1   b , which is facing the free end of the pipe, forms a bearing surface  1   c  for a sealing member or an O-ring seal  5 . The seal  5  may be made from rubber or plastic, and has good resistance to permeation.  
         [0015]    The end segment  2   d  of pipe  2  expands to a conical shape at its end, forming an inner cone  2   a  which provides the location for the O-ring seal  5  at pipe  2 . A threaded part  3  having an external thread is located on the outside of end segment  2   d  of pipe  2 . This external thread is secured by several molded ribs  2   b , which extend outward from the end segment of the pipe  2   d  in the radial and axial directions.  
         [0016]    The threaded part  3  may consist of plastic and may be injection molded onto the end segment  2   d  of pipe  2  by using an appropriate and well-known insert molding technique. In this case, ribs  2   b  are pre-molded. Alternatively, threaded part  3  may also consist of metal, for example, zinc or bronze. In this case, threaded part  3  slides over and onto pipe  2  and its position is fixed by means of ribs  2   b  which are subsequently molded in the corresponding indentations on the threaded part  3 .  
         [0017]    A connecting nut  4  is located on the end segment  1   d  of pipe  1 . This nut is held by an edge area or inwardly extending flange  4   a  which surrounds and engages a portion of the flank  1   f  of the ring-shaped collar  1   b . A thread located on connecting nut  4  engages with the external thread of the threaded part  3 . Therefore, rotation of the connecting nut  4  compresses the O-ring seal  5  between its bearing surface  1   c  and the inner cone  2   a  and therefore ensures that the connection area is sealed. The sealing function is improved by the resiliency of the flanks of ring-shaped collar  1   b , which deflect slightly during the screwing process.  
         [0018]    This pipe connection, which can be reversed if necessary, is particularly suitable for connecting pipes, which carry any media that require gas-impermeable connection methods. The invention is therefore not restricted to pipes that carry fuel.  
         [0019]    Alternatively, the thread part may carry a simple annular groove and the nut has a complementary projection disposed in the groove. In this arrangement the nut simply snaps or clips on the threaded part.  
         [0020]    It should also be appreciated that a groove whether in the form of a simple annular groove or in the form of a continuous thread may be form directly on the pipe  2 .