Claims
- 1. A process for forming an air-gap insulated exhaust manifold, the process comprising the steps of:providing an inner pipe with first and second inner pipe ends; hydrostatic pressing said inner pipe to expand and a portion of said inner pipe and form a branch in said inner pipe; stamping first and second sheets into first and second shells into a shape, said shape being formable into a double wall with, and supporting, said inner pipe when said first and second shells are combined around said inner pipe; placing said inner pipe in said first shell; connecting said second shell to said first shell to form said double wall with said inner pipe and to support said inner pipe in said first and second shells, said shells and said inner pipe ending said double wall at said second end of said inner pipe; connecting inlet tubes to said first end and said branch of said inner pipe, said double wall ending at said inlet tubes; connecting port connection means to said inlet tubes for connecting said inlet tubes to exhaust ports of an engine; connecting exhaust pipe connection means to an end of said double wall adjacent said second end of said inner pipe for connection to an exhaust pipe of the engine.
- 2. A process in accordance with claim 1, wherein:said inner pipe forms a closed path between said first and second ends and said branch.
- 3. A process in accordance with claim 1, wherein:said hydrostatic pressing includes placing the inner pipe in a mold, and pressurizing an inside of said inner pipe in said mold to form said branch in a closed circumference of said pipe section.
- 4. A process in accordance with claim 1, further comprising:forming portions of said inlet tubes with said stamping of said first and second sheets, said portions being homogeneous with said first and second shells; forming said inlet tubes during said connecting of said first and second shells.
- 5. A process in accordance with claim 1, wherein:said shape and said connecting of said first and second shells forms a continuously closed said double wall from said first end and said branch of said inner pipe to said second end of said inner pipe; said ending of said double wall at said first end and branch is spaced from said port connection means; said first and second shells completely surround a circumference of said inner pipe; space between said double wall is filled with gas.
- 6. A process in accordance with claim 1, wherein:said forming of said inner pipe includes providing a plurality of pipe sections with pipe section ends, hydrostatic pressing a plurality of pipe sections to form a branch in each said pipe section, and connecting said pipe section ends of said plurality of pipe sections together to form said inner pipe.
- 7. A process in accordance with claim 1, wherein:said inner pipe is straight and is expanded laterally from an inside in a cold state by mandrel means prior to said hydrostatic pressing; said inner pipe is also bent by said mandrel means prior to said hydrostatic pressing.
- 8. A process in accordance with claim 1, wherein:said hydrostatic pressing forms a dome in a side of said inner pipe and a portion of said dome is cut off to form said branch.
- 9. A process in accordance with claim 1, further comprising:connecting said exhaust pipe connection means directly to said double wall adjacent said second end of said inner pipe; welding said inner pipe to said first and second shells.
- 10. An air-gap insulated exhaust manifold comprising:an inner pipe with a branch formed by hydrostatic pressing, said inner pipe having first and second ends, said inner pipe forming a closed path between said first and second ends and said branch; first and second shells formed from stamped sheets and combined around said inner pipe to form a double wall with, and supporting, said inner pipe, said first and second shells form a continuously closed said double wall from said first end and said branch of said inner pipe to said second end of said inner pipe; inlet tubes connected to said first end and said branch of said inner pipe, said double wall ending at said inlet tubes; port connection means connected to said inlet tubes for connecting said inlet tubes to exhaust ports of an engine; exhaust pipe connection means connected to said second end of said inner pipe for connection to an exhaust pipe of the engine.
- 11. An air-gap insulated exhaust manifold in accordance with claim 10, wherein:portions of said inlet tubes are formed with said stamping of said first and second sheets, and said portions are homogeneous with said first and second shells.
- 12. An air-gap insulated exhaust manifold in accordance with claim 10, wherein:said ending of said double wall at said first end and branch is spaced from said port connection means; said first and second shells completely surround a circumference of said inner pipe.
- 13. An air-gap insulated exhaust manifold in accordance with claim 10, wherein:said inner pipe is formed from a plurality of pipe sections, each said pipe section being hydrostaticly pressed to form said branch, an end of one pipe section being connected to an end of another pipe section to form said inner pipe.
- 14. An air-gap insulated exhaust manifold in accordance with claim 10, wherein:space between said double wall is filled with gas.
- 15. An air-gap exhaust manifold according to claim 10, wherein:said inner pipe is mounted in a sliding seat in said first and second shells.
- 16. An air-gap exhaust manifold according to claim 10, further comprising:a two-dimensional, local spacing means arranged between said first and second shells and said inner pipe, for maintaining a space between a wall formed by said first and second shells and a wall formed by said inner pipe.
- 17. An air-gap exhaust manifold according to claim 16, wherein:said spacing means comprises one of depressions formed in one of said first and second shells and said inner pipe, and shaped wire mesh parts.
- 18. An air-gap insulated exhaust manifold formed by the process of:providing an inner pipe with first and second inner pipe ends; hydrostatic pressing said inner pipe to expand a portion of said inner pipe and form a branch in said inner pipe; stamping first and second sheets into first and second shells into a shape, said shape being formable into a double wall with, and supporting, said inner pipe when said first and second shells are combined around said inner pipe; placing said inner pipe in said first shell; connecting said second shell to said first shell to form said double wall with said inner pipe and to support said inner pipe in said first and second shells, said shells and said inner pipe ending said double wall at said second end of said inner pipe; connecting inlet tubes to said first end and said branch of said inner pipe, said double wall ending at said inlet tubes; connecting port connection means to said inlet tubes for connecting said inlet tubes to exhaust ports of an engine; connecting exhaust pipe connection means to an end of said double wall adjacent said second end of said inner pipe for connection to an exhaust pipe of the engine.
- 19. An air-gap insulated exhaust manifold in accordance with claim 18, wherein:said inner pipe is straight and is expanded laterally from an inside in a cold state by mandrel means prior to said hydrostatic pressing; said inner pipe is also bent by said mandrel means prior to said hydrostatic pressing.
- 20. An air-gap insulated exhaust manifold in accordance with claim 18, wherein:said hydrostatic pressing forms a dome in a side of said inner pipe and a portion of said dome is cut off to form said branch.
Priority Claims (1)
Number |
Date |
Country |
Kind |
44 44 760 |
Dec 1994 |
DE |
|
Parent Case Info
This is a continuation-in-part application of application Ser. No. 08/571,400 filed Dec. 13, 1995, now abandoned.
US Referenced Citations (15)
Foreign Referenced Citations (1)
Number |
Date |
Country |
42 00 611 A1 |
Jul 1993 |
DE |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
08/571400 |
Dec 1995 |
US |
Child |
09/038877 |
|
US |