Patent Publication Number: US-6341595-B1

Title: Laser welded fuel rail and process of making same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority from U.S. Provisional Application Ser. No. 60/165,390, filed Nov. 12, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to fuel rails for internal combustion engines. 
     BACKGROUND OF THE INVENTION 
     Previously, known fuel rails have been formed from low carbon tubular steel. The steel tube was then pierced in several predetermined locations to allow other components to be inserted into the tube, such as fuel cups, hose fittings, and other tubes. At this point, mounting brackets were spot welded onto the tube. A copper paste was applied to joints between the components and the tube. The tube and the attached components were then sent through a brazing furnace to melt the copper at each joint, forming a hermetic, leak-proof seal. This brazing process caused several problems. First, during brazing, the entire tube would severely warp, requiring the tube or the components to be bent into proper position later in the manufacturing process, adding extra steps to the manufacturing process. Second, the brazing process was somewhat unreliable, resulting in leaks in the brazed joints. 
     To the inventors&#39; knowledge, other fuel rails have been formed from two shells which are brazed together, but these rails suffer the same deficiencies as described above. 
     It would be beneficial to develop a fuel rail which does not warp during manufacture, and in which a tight seal can be formed between components. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly, the present invention provides a fuel rail. The fuel rail comprises a first portion including a generally elongated base, at least one mounting bracket and a plurality of fuel cup openings in the generally elongated base. The fuel rail also comprises a second, generally U-shaped, portion having a first and second opposing sides. Each of the first and second opposing sides are sealingly connected to the generally elongated base with a laser weld. The second portion also has a supply end having a fuel supply opening, and a closed end, distal from the supply end. The closed end and the supply end are sealingly connected to the generally elongated base with a laser weld. 
     The present invention also provides a fuel rail assembly. The fuel rail assembly comprises a fuel supply header having a discharge end and a fuel rail connected to the discharge end of the fuel supply header. The fuel rail includes a first portion including a generally elongated base, at least one mounting bracket and a plurality of fuel cup openings in the generally elongated base. The fuel rail also includes a second, generally U-shaped, portion having a first and second opposing sides. Each of the first and second opposing sides is sealingly connected to the generally elongated base with a laser weld. The second portion also has a supply end having a fuel supply opening, and a closed end, distal from the supply end. The closed end and the supply end are sealingly connected to the generally elongated base with a laser weld. The assembly also includes a plurality of fuel injectors, with each of the plurality of fuel injectors being connected to a fuel cup opening, 
     The present invention also provides a method of manufacturing a fuel rail. The method comprises forming a first portion having at least one integral mounting bracket; a deep drawing a second, generally U-shaped portion having first and second opposing sides, a closed end and a supply end; and sealingly connecting the first and second opposing sides, the closed end, and the supply end to the first portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated herein, and constitute part of this specification, illustrate the presently preferred embodiment of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings: 
     FIG. 1 is a perspective view of two fuel rails according to a preferred embodiment of the present invention, with a fuel supply header and a plurality of fuel injectors connected to each fuel rail; 
     FIG. 2 is an enlarged perspective view of a portion of the fuel rail shown in FIG. 1; 
     FIG. 3 is a sectional view of the fuel rail taken along line  3 — 3  of FIG. 2; and 
     FIG. 4 is an enlarged perspective view of an interface between the fuel rail and a fuel supply line. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, fuel rails  10 ,  10 ′ according to a preferred embodiment are shown, with a fuel supply header  20  and three fuel injectors  30  connected to the fuel rail  10 . In the drawings, like numbers indicate like elements throughout. The fuel rails  10 ,  10 ′, together with the fuel supply header  20  and fuel injectors  30 , form a fuel supply assembly  100 . The fuel supply header  20  splits into two fuel supply lines  22 , with each fuel supply line  22  supplying fuel to a separate fuel rail  10  and  10 ′. A fuel pressure regulator  23  is located in the fuel supply header  20  where the fuel supply lines  22  split. Fuel rails  10  and  10 ′ are preferably mirror images of each other, and only fuel rail  10  will be described herein. Those skilled in the art will recognize that the present description pertains to fuel rail  10 ′ as well. 
     Referring now to FIG. 2, which shows the fuel rail  10  only, the fuel rail  10  is constructed of two portions, a first, or lower portion  110 , and a second, or upper portion  130 . The fuel rail  10  includes a longitudinal axis  102  extending therethrough. 
     The lower portion  110  is preferably formed from stainless steel and includes a generally elongated base  111  and at least one, and preferably two, integrated mounting brackets  112 . Preferably, the lower portion  110  is stamped from a single sheet of material. A base  111  having an integrated mounting bracket  112  which can be incorporated into the present invention is disclosed in U.S. patent application Ser. No. 09/606,538, filed on even date, which is incorporated herein in its entirety by reference. 
     The base  111  is generally planar and includes a first end  114 , a second end  116 , a top face  118 , an opposing bottom face  120 , a first longitudinal side  122  and a second longitudinal side  124 . The base  111  includes a plurality of injector cups  32  which extend down from the bottom face  120  and connect to each of the fuel injectors  30 . The injector cups  32  provide for fluid communication between the interior of the fuel rail  10  and the fuel injectors  30 . Preferably, the injector cups  32  are deep drawn, which is well known to those skilled in the art. 
     Each mounting bracket  112  is integrally formed with the base  111  and is formed from the same sheet of material as the base  111 . Preferably, each mounting bracket  112  extends from the first longitudinal side  122 , although those skilled in the art will recognize that a mounting bracket  112  can extend from the second longitudinal side  124  or either of the first and second ends  114 ,  116 , respectively. Each mounting bracket  112  preferably includes at least one through hole  113  through which a mounting bolt (not shown) can be inserted to attach the fuel rail  10  to a surface, such as an engine block (not shown). 
     The upper portion  130  is preferably formed by deep drawing a sheet of material into a generally inverted U-shape. Preferably, the upper portion  130  is formed from stainless steel, although those skilled in the art will recognize that the upper portion  130  can be formed from other suitable materials. The upper portion  130  includes a top surface  132 , first and second opposing sides  134 ,  136 , respectively, which are generally parallel to the longitudinal axis  102 , a closed end  138  and an open, or supply, end  140 , distal from the closed end  138 . The first and second sides  134 ,  136  are each located along the first and second longitudinal sides  122 ,  124 , respectively, of the lower portion  110  such that the first and second sides  134 ,  136  and the closed end  138  of the upper portion  130  rest on the top face  118  of the lower portion  110 , forming a butt joint between the lower portion  110  and the upper portion  130 . 
     With the upper portion  130  engaging the lower portion  110 , as shown in FIG. 3, the upper portion  130  is fixedly connected to the lower portion with a laser weld  142 . 
     The laser weld  142  is provided around the entire fuel rail  10  where the upper portion  130  and the lower portion  110  contact, providing a hermetic seal between the upper portion  130  and the lower portion  110 . 
     As shown in FIG. 4, the supply end  140  of the upper portion  130  includes an opening  142  extending therethrough which fluidly communicates the fuel supply line  22  with the interior of the fuel rail  10 . The supply end  140  of the upper portion  130  also includes a swivel fitting  150  (shown in dashed lines in FIG. 4) which is laser welded into the opening  142 . The swivel fitting  150  includes a welded end  152  and a free end  154 . The fuel supply line  22  has a discharge end  24  which is generally tubular in shape. The discharge end  24  includes an o-ring  26  or other sealing device on the outer diameter of the discharge end  24 . The discharge end  24  and the o-ring  26  are sized to be inserted into the free end  154  of the swivel fitting  150 . After the discharge end  24  and the o-ring  26  are inserted into the free end  154  of the swivel fitting  150 , the free end  154  of the swivel fitting  150  is rolled over, or crimped to the discharge end  24  to secure the supply line  22  with the o-ring  26  onto the swivel fitting  150 . The supply line  22  is free to rotate about the longitudinal axis  102 , allowing for better alignment and installation of the supply line  22  with the fuel rail  10 . 
     It will be appreciated by those skilled in the art that changes could be made to the embodiment described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiment disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined in the appended claims.