Patent Publication Number: US-2006016416-A1

Title: Polymeric manifold assembly and method

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of U.S. Provisional Application No. 60/581,017, filed Jun. 18, 2004, which is incorporated by reference herein as if fully set forth. 
    
    
     BACKGROUND  
      The present invention pertains to the field of engine intake manifolds. It is particularly related to methods of forming engine intake manifold assemblies.  
      In most vehicles built in the last decade, intake manifold assemblies are typically manufactured by a molding process. This has commonly been done by a process known as lost core molding, wherein a desired material is heated to liquid form and placed in a mold around a core. Cores made of high temperature wax or foam are used when the part to be molded has complex internal geometry. When the material has cooled to form the manifold, the core is then removed, for example by heating so that it melts, producing with complex inner passageways inside the manifold that are required to distribute a fuel/air mixture from throttle body fuel injectors or a carburetor to the intake ports in the head(s).  
      Although this known method produces a manifold assembly in a single molding process, lost core molding is financially unfeasible for smaller manufacturers due to its high expense. In an effort to find a more cost effective method of production, the manifold assemblies have also been formed by molding two separate sections of the manifold out of glass filled plastic, and then joining the two sections with a structural adhesive.  
     SUMMARY  
      In order to produce the intake manifold assemblies in a more cost effective manner, while ensuring that the structural integrity and functional requirements of the manifold are maintained, the present invention employs a method in which three sections of the manifold are separately formed of a polymeric material, for example nylon 6 or nylon 6/6, in an injection molding process. Each section defines portions of the complex internal passageways as open cavities having positive draft angles that can be formed using conventional injection molding techniques. The three sections include complementary interfacing surfaces, which are used in joining the three sections together to form the manifold assemblies so that the cavities are aligned and sealed together to define the internal passageways, preferably through vibration or ultrasonic welding. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING(S)  
       FIG. 1  is an isometric view of the assembled engine intake manifold.  
       FIG. 2  is an exploded, isometric view showing the three sections of the engine intake manifold assembly.  
       FIG. 3  is an exploded side view showing the three sections of the engine intake manifold assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
      Certain terminology is used in the following description for convenience only and is not considered limiting. Words such as “front”, “back”, “top” and “bottom” designate directions in the drawings to which reference is made. This terminology includes the words specifically noted above, derivatives thereof and words of similar import. Additionally, the terms “a” and “one” are defined as including one or more of the referenced item unless specifically noted. The phrase “at least one” followed by a list of two or more items (such as A, B, or C) means any individual one of A, B or C as well as any combination thereof.  
      The preferred embodiments of the present invention are described below with reference to the drawing figures where like numerals represent like elements throughout.  
      As shown in  FIG. 1 , an engine intake manifold assembly  1  in accordance with the present invention is shown. The manifold  1  is formed by joining a top section  10 , a middle section  20 , and a bottom section  30 . The manifold assembly  1  includes complex internal passageways for uniformly distributing fuel from a source, such as a carburetor or throttle body fuel injectors, to the intake ports of the head(s). The top section  10 , middle section  20 , and bottom section  30  are made from a polymeric material. In a preferred embodiment, the top, middle, and bottom sections  10 ,  20 ,  30  are made from nylon 6 or nylon 6/6. However, other materials can be used depending on the particular application.  
      Referring to  FIG. 2 , the top section  10 , middle section  20 , and bottom section  30  each have a plurality of cavities  14 ,  28 , and  32 , respectively. The cavities are designed as portions of the complex internal manifold passageways and have positive draft angles so that each section can be molded in a conventional injection molding process, preferably with two piece tools. This allows the sections  10 ,  20 ,  30  to be freely released from the tool surfaces due to the cavity design.  
      The cavities  14 ,  28 ,  32  on the respective parts have interfacing surfaces  12 ,  22 ,  24 , and  34  that are complementary to one another, so that upon assembly, the required internal passageways are formed having generally the same geometry of a one-piece manifold manufactured by lost core molding. The surface area at the interfacing surfaces  12 ,  22 ,  24 ,  34  are of a sufficient size for welding and/or fastening, preferably in the range of 0.25 inch (6 mm) or under. The interfacing surfaces  12 ,  22 ,  24 , and  34  can be held to close tolerances in the molding process so that they can be closely fit and aligned for sealing the respective internal passageways during the welding and/or fastening process.  
      Referring to  FIGS. 2 and 3 , the top section  10  has a lower mating surface  12 . The middle section  20  has an upper mating surface  22  that is complementary to the lower mating surface  12  of the top section  10 , and a lower mating surface  24 . The bottom section  30  has an upper mating surface  34  that is complementary to the lower mating surface  24  of the middle section  20 . These surfaces are preferably flat, or may have protrusions and recesses to assist in alignment and/or welding.  
      The manifold assembly  1  is formed by joining the lower mating surface  12  of the top section  10  with the upper mating surface  22  of the middle section  20 , and by joining the lower mating surface  24  of the middle section  20  with the upper mating surface  34  of the bottom section  30 . The sections are joined at the surfaces through either vibration or ultrasonic welding. In a preferred embodiment, weldment tabs  16 ,  26 ,  36  can be used to enlarge the surface areas of the mating surfaces  12 ,  22 , 24 , 34  for welding. During vibration welding the plastic at the interfacing surfaces becomes molten and provides a seal when it cools. The vibration or ultrasonic welding is done in accordance with known practices. Accordingly, a further description of the vibration or ultrasonic welding is not provided herein.  
      In accordance with the invention, a resin, for example a liquid resin can be applied on the mating surfaces to assist in sealing/welding to ensure a uniform and consistent weld and that sealing occurs between the internal passageways that are formed.  
      As shown in  FIG. 1 , the manifold  1  thus formed includes the required mounting holes for installation on an engine. Further, the manifold  1  can include molded in inserts at bolt locations as well as stand offs for accessory mounting in the manner of an OEM (original equipment manufacturer) manifold. Overall dimensions of manifold  1  preferably match an OEM manifold or are designed to fit existing OEM applications. The manifold  1  can alternatively include additional reinforcements in known failure areas of a related OEM part. Providing such reinforcements or other modifications is facilitated by the unique three part design of the manifold  1  which allows for more versatile and less costly tooling.  
      While the preferred embodiments of the invention have been described in detail above, the invention is not limited to the specific embodiments described above, which should be considered as merely exemplary. Further modifications and extensions of the present invention may be developed, and all such modifications are deemed to be within the scope of the present invention as defined by the appended claims.