Pipe assembly having inner and outer pipes

摘要

A pipe assembly includes an inner pipe and an outer laminated pipe disposed around the inner pipe for use in conveying exhaust gases from an internal combustion engine. The outer pipe is formed from two or more laminated layers to reduce noise emission. The outer pipe surrounds the inner pipe to protect the inner pipe, and muffle the inner pipe, while the inner pipe provides support for the outer pipe, either consistently contacting the outer pipe at the upstream inlet portion, or contacting the outer pipe at three areas spaced from each other on the outer pipe at the downstream outlet portion. The three contacting areas at the downstream outlet portion create an air-filled space at least partially separating the inner pipe and the outer laminated pipe. The air-filled space insulates the inner pipe so that exhaust gases moving through the inner pipe do not cool significantly as a result of heat dissipating by conduction or convection to the outer pipe. A set of such pipe assemblies can be used in an exhaust manifold of an internal combustion engine.