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  Dual wall exhaust manifold and method of making sameRelated Patent Categories: Power Plants, Internal Combustion Engine With Treatment Or Handling Of Exhaust Gas, Common Receiver Having Inlets From Plural Cylinder (i.e., Exhaust Manifold)The Patent Description & Claims data below is from USPTO Patent Application 20070180820. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This non-provisional application claims the benefit of U.S. Provisional Patent Application No. 60/756,238, entitled "DUAL WALL EXHAUST MANIFOLD," filed Jan. 3, 2005, which is hereby incorporated by reference in its entirety. FIELD OF ART [0002] The present invention relates generally to exhaust manifolds, and more specifically, to dual-wall exhaust manifolds for use with internal combustion engines. BACKGROUND OF THE INVENTION [0003] Many modern high performance engines generate extremely hot gas emissions. As these emissions are expelled from the engine and pass through the exhaust manifold, the hot emissions heat the exhaust manifold or pipes to increasingly high temperatures. Such high temperatures cause the temperature of the tubes to elevate resulting in discoloration of the tubes. As such, some component designs utilize a dual wall construction that utilizes an air gap between the inner and outer tubes. Known dual wall manifolds utilize spacers and stub tubes to properly space the inner and outer tubes. The air gap insulates the outer tube from the inner tube. As a result, the inner tube is insulated from significant heat transfer to the outer tube. Therefore, discoloration and excessive heating are minimized. However, use of stub tubes, spacers and the related labor associated with these components is costly. [0004] In order to manufacture the components of the manifold in a cost and labor efficient manner, manufacturers balance many factors including weld placement, weld types, component numbers, thermal expansion of components and the like. Each of these components is vital in manufacturing cost effective dual-wall components that perform and act properly under working conditions. [0005] For example, allowing for thermal expansion tolerances is required for a properly manufactured and designed manifold assembly. Specifically, the inner tubes and other components are heated to higher temperatures than the outer tubes. Therefore, allowing for thermal expansion of the inner components is essential in a properly functioning dual-wall manifold assembly. [0006] Furthermore, manufacturing costs of a manifold assembly can be significant, and a continual need in the industry is to reduce these manufacturing costs. Reducing the number of components of the manifold assembly can significantly reduce manufacturing and labor costs. In addition to reducing costs, the industry continues to seek any improvement in strength and durability of the assembly. Placement and type of the weld, for example, can be important in terms of manufacturing costs as well as overall strength and durability of the manifold assembly. [0007] Therefore, there is a need in the art to provide a dual-wall exhaust manifold that can overcome at least several of the above disadvantages and achieve at lease some of the above advances desirable in the art. SUMMARY OF INVENTION [0008] A dual wall exhaust manifold assembly is provided. The manifold has an outer shell and an inner shell spaced apart to allow for an air gap between the shells. To ease in manufacture and assembly, the inlet flange and the outlet flange have counterbores. The counterbore of the outlet flange aids in spacing the inner shell and the outer shell. The inner shell is connected to the outlet flange with a slip fit joint. The counterbore of the outlet flange provides an area to weld the outer shell to the outlet flange. The counterbore of the inlet flange allows space for welding the inner shell to the inlet flange. Advantageously, the manifold assembly of the present invention eliminates components typically required for manufacture of a dual wall exhaust manifold, such as stub tubes and spacers. DESCRIPTION OF THE DRAWINGS [0009] Objects and advantages together with the operation of the invention may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein: [0010] FIG. 1 illustrates inner shell joints of a dual-wall exhaust manifold assembly in an embodiment of the present invention. [0011] FIG. 2 illustrates outer shell joints of a dual-wall exhaust manifold assembly in an embodiment of the present invention. [0012] FIG. 3 illustrates a cross-sectional view of a welded connection between an inlet flange and an inner shell of a dual-wall manifold assembly in an embodiment of the present invention. [0013] FIGS. 4 and 5 illustrates an underside view of a dual-wall exhaust manifold assembly in an embodiment of the present invention. [0014] FIG. 6 illustrates an outer shell and an inner shell connected to an outlet flange of a dual-wall exhaust manifold in an embodiment of the present invention. [0015] FIG. 7 illustrates an outer shell and an inner shell connected to an inlet flange of a dual-wall exhaust manifold in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [0016] Although the preferred embodiment of the invention has been illustrated in the accompanying drawings and described in the subsequent detailed description, it is to be understood that the invention is not to be limited to just the preferred embodiment disclosed, but that the invention described herein is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the claims as appended hereafter. [0017] Referring to the drawings, a dual-walled exhaust manifold 10 having a body or log 11 is provided. The body 11 includes an outer shell 12 and an inner shell 14 connected to an outlet flange 16 and an inlet flange 18. The body 9 of the manifold 10 is in fluid communication with each of several runners 11a-11d, shown in the drawings as four in number. The illustrated manifold 10 can, for example, have any number of runners for any number of cylinders of an engine. For example, the manifold 10 can be used in a V-8 engine where the manifold 10 may be duplicated on the opposite side of the engine. The manifold assembly 10 is attachable to an engine block and the outlet (or exhaust) flange 16. Exhaust from a vehicle engine, for example, flows from the engine through passageways into the inlet flange 18 and in the runners 11a-11d. The engine exhaust is expelled from the manifold 10 through the outlet flange 16. [0018] The outer shell 12 and the inner shell 14 may be formed from two or more components. Preferably, the outer shell 12 and the inner shell 14 are formed from two portions joined along a centerline of the shells 12, 14. It is also anticipated that each of the shells 12, 14 may be integrally formed. In a preferred embodiment, the outer shell 12 substantially surrounds and/or encloses the inner shell 14. The outer shell 12 may have several channels 13 corresponding in number and shape to the runners 11a-11d of the inner shell 14. The outer shell 12 and the inner shell 14 are positioned so that an air gap is formed between the shells 12, 14 as illustrated in FIG. 3. Continue reading... Full patent description for Dual wall exhaust manifold and method of making same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Dual wall exhaust manifold and method of making same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Dual wall exhaust manifold and method of making same or other areas of interest. ### Previous Patent Application: Process and system for improving combustion and exhaust aftertreatment of motor vehicle engines Next Patent Application: Heavy-construction machine Industry Class: Power plants ### FreshPatents.com Support Thank you for viewing the Dual wall exhaust manifold and method of making same patent info. 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