Patent ID: 6868939
Filing Date: 2005-03-22
Classification: F01N

Abstract:
1. An exhaust system for an internal combustion engine, comprising: a muffler including an outer shell having imperforate walls, an intermediate shell having perforated walls spaced inwardly of the outer shell walls, sound absorbing material disposed within a first volume defined between the outer shell and the intermediate shell, an inner shell having perforate walls spaced inwardly of the intermediate shell walls, die the inner shell defining a second volume, sound absorbing material disposed within the second volume, the wall with the inner shell and the intermediate shell defining an annular space for flow of exhaust gases from an internal combustion engine, the annular space having an inlet end and an outlet end; an inlet pipe to the inlet end of the annular space, the inlet pipe having a variable inner diameter that increases in the direction of flow of the exhaust gases; an outlet pipe from the outlet end of the annular space, the outlet pipe having an inner wall that extends smoothly away from the intermediate shell and toward the outer shell to provide a gradually expanding exhaust flow path from the outlet end of the annular space, thereby reducing abrupt transitions in the exhaust flow path, whereby a negative pressure wave generated when a confined pressure wave encounters an enlargement of the flow path at the outlet end of the annular space is of lower intensity and longer duration than without the inner wall; and an inlet flow diverter that projects from the inner shell away from the inlet end of the annular space, the flow diverter having a leading tip and walls that diverge from the leading tip toward the annular space to guide exhaust gases into the annular space.