Pipe assembly having inner and outer pipes

Details Pipe assembly having inner and outer pipes Pipe assembly having inner and outer pipes

1998-09-28

2001-04-03

Denion, Thomas (Department: 3745)

Power plants

Internal combustion engine with treatment or handling of...

Common receiver having inlets from plural cylinder

C060S322000, C060S272000, C285S179000, C138S114000, C138S143000

Reexamination Certificate

active

06209319

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to pipes that convey exhaust gases from an internal combustion engine, and more particularly to a pipe assembly for conveying exhaust gases that includes inner and outer pipes.
2. Description of the Related Art
Some existing exhaust manifold designs include a set of single-walled pipes emanating from an internal combustion engine and connected to downstream pipes. Significant noise is generated, however, when exhaust gases are conveyed from an internal combustion engine through a set of single-walled pipes emanating from the engine.
Single-walled pipes are susceptible to thermodynamic heat loss, which impedes operation of a catalytic converter, caused by the ambient atmosphere surrounding the single-walled pipe. Single-walled pipes are also easily damaged by impact, dirt, debris and corrosive substances. Because single-walled pipes suffer from the aforementioned and other shortcomings, there have been attempts to convey exhaust gases through double-walled pipes.
For example, in U.S. Pat. No. 4,022,019 to Garcea, two outer corrugated tubes are slipped over an inner smooth tube. The outer corrugated tubes insulate the inner tube, reducing heat transfer toward the outside atmosphere.
In U.S. Pat. No. 5,390,494 to Clegg, an inner pipe is surrounded by a thicker outer pipe. Corrugations in the inner pipe provide support during bending and reduce heat dissipation to the surrounding areas.
There continues to be a need, however, for new structural arrangements that reduce engine noise emitted by exhaust gas conduits while preventing heat dissipation from the exhaust gas conduits.
SUMMARY OF THE INVENTION
According to an exemplary embodiment of the invention, a pipe assembly for conveying exhaust gases includes an inner pipe and an outer pipe disposed around the inner pipe. The outer pipe includes an outer layer and an inner layer attached, such as by lamination, to the outer layer. Noise emitted from the pipe assembly is reduced by laminating the outer layer and the inner layer and selecting the thickness of the outer layer to be twice the thickness of the inner layer. A set of such pipe assemblies can be deployed in pairs in an exhaust manifold. When paired, the planar side wall of one of the pipe assemblies is in confronting relation with the planar side wall of the other pipe assembly of the pair.
Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention.


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