Abstract: 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.

Abstract: An exhaust manifold for an internal combustion engine includes one or more pairs of pipe members. Each pipe member has a downstream end portion, and includes along its downstream end portion a side wall in opposing relation with, and concave with respect to, the side wall of the other pipe member of the pair. The pipe members are joined at only two contacting areas of their respective downstream end portions. A gap is defined by the opposing concave side walls in which the side walls expand and contract while heating and cooling. Each of the pair of pipe members includes an outer pipe and an inner pipe disposed within the outer pipe. The inner pipe contacts the outer pipe at three contacting areas that are spaced from each other on the outer pipe so that an air-filled space at least partially separates the inner pipe and the outer pipe. Exhaust gases from the internal combustion engine are conveyed through such pairs of pipe members downstream to one or more exhaust pipes.