Patent Publication Number: US-6213101-B1

Title: Method and apparatus for blocking fluid and fuel vapors

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to a method and apparatus for blocking fluid and fuel vapors. More particularly, the present invention relates to a unique method and construction of an apparatus for preventing fluid leakage and vapor migration through the use of electrical wires. 
     2. Discussion 
     Conventional automotive fuel delivery systems utilize an electric fuel pump mounted in a fuel tank to deliver fuel from the fuel tank to the engine. Power is supplied to the fuel pump through electric wires connected between the fuel pump and a voltage source such as an alternator or a vehicle battery. In order to reach the fuel pump, the electrical wires must pass through an opening in the fuel tank. Such an opening, unless properly sealed, potentially provides a pathway for fluid leakage and fluid vapor migration commonly referred to as vapor permeation. Minimizing such fluid leakage and vapor permeation is desirable due to increasing regulations regarding automotive fuel vapor emissions and overall product efficiency. 
     Several attempts to seal this opening in the fuel tank have been developed. Many of these contributions to the art include a bushing or a fitting adapted for placement in the opening. The electrical wires then pass through this bushing or fitting. Although the wires are fitted together as tightly as possible through the bushing or fitting, spaces or pores inevitably exist through which fluid leakage and vapor permeation is released. 
     In other contributions to the art, fluid leakage and vapor permeation is attempted to be prevented through the use of numerous continuous wires, the center portions of which are stripped of insulation. A plug is then placed over the exposed center insulation stripped wire portion. The entire composite is then blocked through a chemical bath treatment. Such a contribution is illustrated in U.S. Pat. No. 5,631,445 (Herster). Such contributions typically include production processes which are laborious and expensive, further possibly requiring separate internal and external harnesses. Moreover, the use of insulated continuous wire is rather costly and wasteful since this high end type of wire is only required in the area inside the fuel tank and not throughout the entire vehicle. Wires in the fuel tank are typically specially cured such as through chemical baths or through exposure to radiation to strengthen their various necessary attributes. This greatly increases the cost of the wires. 
     As set forth above, in order to maintain electrical integrity, the electrical wires are typically wrapped with expensive insulation. Some such wire insulation swells when exposed to fluid or vapor permeation which may cause cracking and/or breakage. Other types of insulation shrink when exposed to fluid or vapor permeation, thus increasing the size of the pathway through which fluid leakage or vapor permeation may escape. When the insulation on the wires passing through a fitting deteriorates due to shrinking or swelling, or when the wires are not sufficiently bound to the fitting, the area between the wire and the fitting are widened providing a greater pathway through which fluid leakage or vapor permeation may be released. 
     In other processes, the center of the conductors is stripped and through a vacuum process, a fuel resistant sealant is introduced to fill the pores between the wires and the fitting. New wire is also being developed which includes a blocking agent added during the extrusion process. 
     The current contributions to the art do not effectively compensate for the problems set forth above, in part by failing to adequately seal and close the space between the wires and the fitting, and by failing to sufficiently bond the wires to the fitting. In order to overcome the problems associated with the current contributions to the art, various designs and methods for blocking fluid and fuel vapors have been developed. The continued development has been directed to designs which simplify the manufacturing process and assembly while keeping costs at a minimum and performance at a maximum. 
     SUMMARY OF THE INVENTION 
     It is a principal object of the present invention to provide a method and apparatus for blocking fluid and fuel vapors which eliminates the minute pathways from which fluid leakage and vapor permeation may escape. The term “fluid” will be used throughout, however, it will be appreciated that this term includes both fluid and vapor. 
     A related object of the present invention is to provide a method and apparatus for blocking fluid and fuel vapors which allows for the use of a solid wire inside the fuel tank and a more cost effective wire outside the fuel tank. 
     It is another object of the present invention to provide a method and apparatus for blocking fluid and fuel vapors which includes welding two separate wires together forming one continuous wire, wherein a consistent, solid barrier is created within the weld. This welded section is then overmolded with a fuel resistant plastic resin. 
     It is still yet another object of the present invention to provide a method and apparatus for blocking fluid and fuel vapors which is inexpensive to manufacture and easy to install. 
     It is another object of the present invention to provide a method and apparatus for blocking fluid and fuel vapors which does not require the laborious and costly process of dipping the wires into a chemical bath. 
     It is another object of the present invention to provide a method and apparatus for blocking fluid and fuel vapors that utilizes a more costly, solid, insulated wire inside the fuel tank and a more cost effective automotive grade wire outside the fuel tank. 
     In one form, the present invention provides a method for blocking fluid and fuel vapors including electrical wires. The method of the present invention includes the general steps of cutting an electrical wire and stripping the wire of its insulation at the cut ends. The wires are then bonded back together through the use of welding. The term “welding” will be used throughout, however, it will be appreciated that any commonly known bonding or adhering means may be utilized including, but not limited to, soldering, ultra sonic welding, resistance welding, tungsten-inert gas (hereinafter “TIG”) welding, or gas metal arc welding. Finally, this welded section, plus a portion of the wire insulation is overmolded with a fuel resistant plastic resin. 
     In another form, the present invention provides an apparatus for blocking fluid and fuel vapors including electrical wires which are cut and stripped of their insulation at the cut ends. The wires are then bonded back together through the use of welding. The welded section, plus a portion of the wire insulation, is then overmolded with a fuel resistant plastic resin. 
    
    
     Other advantages, benefits and objects of the present invention will become apparent to those skilled in the art from a reading of the subsequent detailed description, appended claims and accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the best mode presently contemplated for carrying out the present invention: 
     FIG. 1 is an environmental view of a method and apparatus for blocking fluid and fuel vapors constructed in accordance with the teachings of a preferred embodiment of the present invention shown incorporated into a motor vehicle, the remainder of the vehicle is shown in phantom lines; 
     FIG. 2 is a top view of the method and apparatus for blocking fluid and fuel vapors shown in FIG. 1; 
     FIG. 3 is a sectional view taken along the line  3 — 3  of FIG. 2; 
     FIG. 4 is a perspective view of a forming nest used in association with a TIG welding process in accordance with the teachings of a preferred embodiment of the present invention; and 
     FIG. 5 is a sectional view taken along the line  5 — 5  of FIG. 2 illustrating a method and apparatus for blocking fluid and fuel vapors constructed in accordance with the teachings of a second preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, there is depicted an apparatus for blocking fluid and fuel vapors embodying the concepts of the present invention. The apparatus of the present invention is generally identified in the drawings with reference numeral  10  and is shown in FIG. 1 adapted to cooperate with a specific fuel delivery system of a motor vehicle  12 . However, the teachings of the present invention are more broadly applicable to other automotive applications where fluid leakage and/or vapor migration prevention is desirable (i.e., transmission harnesses). 
     Prior to addressing the construction and operation of the apparatus  10  of the present invention, a brief understanding of the exemplary fuel delivery system of the motor vehicle  12  shown in FIG. 1 is warranted. The environmental view of FIG. 1 illustrates the apparatus  10  operatively attached to a fuel delivery system of the vehicle  12 . The fuel delivery system provides fuel to an engine  14  and includes a fuel tank  16  located in a rear section  12   a  of the vehicle  12  in which a fuel delivery module  18  is mounted in any commonly known manner. The fuel delivery system also includes a pair of fuel lines  20 , one for delivering fuel from the fuel tank  16  to the engine  14  and the other for returning fuel from the engine  14  to the fuel tank  16 . Fuel delivery module  18 , which is mounted to the fuel tank  16 , has an electric fuel pump  22  connected to one of the fuel lines  20 , a pump sender  24  for signaling the fuel level within the fuel tank  16 , and a fuel filter  26  on an inlet side of the electric fuel pump  22 . Electrical wires  28  pass through the fuel tank  16  to supply the electric fuel pump  22  and the pump sender  24  with electrical power from a battery  30 . A plug body  34  according to the present invention provides a sealed conduit for the electrical wires  28  to pass through the fuel tank  16  while minimizing fluid leakage and vapor permeation therefrom. As will be understood by those skilled in the art, FIG. 1 is for illustrative purposes only and not meant to indicate a specific vehicle or fuel delivery system, and is but one adaptation for which the present invention can appropriately be used. 
     Referring now to FIG.  2  and FIG. 3, the apparatus for blocking fluid and fuel vapors  10  is shown including the plug body  34 . The plug body  34  includes an enlarged central portion  36  having a plurality of bores  38  formed therethrough. The enlarged central portion  36  is preferably integrally formed with the plug body  34 , and includes an upwardly projecting portion  39  projecting upward from a top surface  40  and a downwardly projecting portion  41  projecting downward from a bottom surface  42 . The plug body  34  is fitted into an opening in the fuel tank  16  and is welded to the fuel tank  16  in such a manner that the downwardly projecting portion  41  of the enlarged central portion  36  extends downward into the fuel tank  16 . The plug body  34  is fitted into the opening in the fuel tank  16  such that a perimeter portion  43  of the plug body  34  is welded over the opening in the fuel tank  16 . 
     As illustrated in FIG. 3, the electrical wires  28  pass through the bores  38  formed in the enlarged central portion  36  of the plug body  34 . The electrical wires  28  may include a first wire  44  and a second wire  46 . The first wire  44  is located outside the fuel tank  16  and is typically a more cost effective automotive grade wire commonly known in the industry, or a stranded electrical wire, or a solid electrical wire. The second wire  46  is located in the fuel tank  16  and is typically specially cured such as through chemical baths or through exposure to radiation to strengthen its various necessary attributes, or a stranded electrical wire, or a solid electrical wire. The first wire  44  and the second wire  46  have insulation  48  and  50 , respectively, thereon to secure electrical integrity and prevent short circuits as is commonly known. Preferably, the insulation  50  of the second wire  46  is fuel resistant, for example, a moisture cured or irradiated, high density polyethylene insulation, which swells only minimally when exposed to fuel so as to prevent cracking and breaking of the insulation  50  of the second wire  46  located in the fuel tank  16 . In some instances, the second wire  46  having fuel resistant insulation  50  secured thereon may be used not only inside the fuel tank  16  but also outside the fuel tank  16  as well. In such instances, the wire is cut into two pieces prior to its placement within the bores  38  formed in the enlarged central portion  36  of the plug body  34 . 
     With continued reference to FIG. 3, the first wire  44  and the second wire  46  have end portions  52  and  54 , respectively. The end portions  52  and  54  are encased within the plug body  34 . The insulation  48  of the first wire  44  is stripped at the end portion  52 . Likewise, the insulation  50  of the second wire  46  is stripped at the end portion  54 . The stripped end portion  52  of the first wire  44  and the stripped end portion  54  of the second wire  46  are then bonded back together through welding. Thus forming one contiguous wire having a welded wire section  56 . In instances where one contiguous piece of wire is utilized, which has been cut into two pieces prior to placement within the bores  38 , each end portion is similarly stripped of its insulation and then bonded back together as described above. This process thus creates a welded wire section  56  of solid, or virtually solid copper, which eliminates a pathway for fluid leakage and vapor permeation. Due to the constraints of the welding equipment, the welded wire section  56  does not butt up against the insulation. 
     Referring now to FIG. 4, an alternative welding process is illustrated using a forming nest. As is commonly known in the industry, TIG welding is welding in which an arc from a nonconsumable tungsten electrode radiates heat onto a work surface, to create a weld puddle in a protective atmosphere provided by a flow of inert shielding gas. Pressure may or may not be used and filler metal may or may not be used. The forming nest includes an upper portion (not shown) and a lower portion  58 . The upper portion (not shown) of the forming nest is substantially similar to and a mirror image of the lower portion  58  of the forming nest. The upper portion of the forming nest differs primarily from the lower portion  58  in having a passageway extending vertically throughout its entire height. As illustrated in FIG. 4, the lower portion  58  of the forming nest is provided having a first channel  60  and a second channel  62  formed therein. The first channel  60  and the second channel  62  formed in the lower portion  58  of the forming nest are adapted to receive the first wire  44  and the second wire  46 . Also formed in the lower portion  58  of the forming nest, between the first channel  60  and the second channel  62 , is a central mold region  64 . The central mold region  64  can be of any geometric shape, for example, a sphere, a rectangle or any other shape that is required by the end user. 
     During the TIG welding process, as illustrated in FIG. 4, the first wire  44  is received in the first channel  60  and the second wire  46  is received in the second channel  62 , such that the stripped end portion  52  of the first wire  44  and the stripped end portion  54  of the second wire  46  each extend into the central mold region  64 . It is appreciated by one skilled in the art that the first wire  44  is equally capable of being received in the second channel  62  while the second wire  46  is equally capable of being received in the first channel  60 . During the welding process, a weld puddle is then captured in the central mold region  64  formed in the lower portion  58  of the forming nest. Thereafter, a weld nugget in the desired geometric shape, the geometric shape of the central mold region  64 , is created. The weld nugget formed is a solid, consistent mass of copper. 
     Following the welding process, the welded wire section  56  or the weld nugget, plus a portion of the insulation  48  of the first wire  44  and a portion of the insulation  50  of the second wire  46  are overmolded with a fuel resistant plastic resin, by way of example, in the acetyl family, to form an overmolded section  66 . Accordingly, the overmold covers and bonds together a portion of the insulation  48  of the first wire  44 , a portion of the insulation  50  of the second wire  46 , and the welded wire section  56  or the weld nugget. Thus further interrupting and eliminating any pathways for fluid leakage and vapor permeation. 
     An alternative embodiment of a method and apparatus for blocking fluid and fuel vapors  100  is illustrated in FIG.  5 . The method and apparatus for blocking fluid and fuel vapors  100  differs primarily from the previous embodiment  10  in the location of the welded wire section  56  or the weld nugget. In the method and apparatus for blocking fluid and fuel vapors  100 , like reference numerals will be used to describe like components. 
     In the method and apparatus for blocking fluid and fuel vapors  100 , a welded wire section  102 , or weld nugget, and an overmolded section  104  are created as described above. As illustrated in FIG. 5, the welded wire section  102  or the weld nugget (not shown) for each alternating electrical wire  28  of the method and apparatus for blocking fluid and fuel vapors  100  are staggered or offset. This formation further secures electrical integrity and further prevents short circuits as is commonly known. 
     A plug body  34  as described above provides a sealed closure which prevents fluid leakage and vapor permeation while also affording greater cost benefits by utilizing more costly wire only where needed. 
     While the above detailed description describes the preferred embodiment of the present invention, it should be understood and appreciated that the invention is susceptible to modification, variation and alteration without departing from the proper scope and fair meaning of the accompanying claims.