Patent ID: 9605577
Date: 2017-03-28
CPC Classifications: F01N

Claim:
1. An exhaust passage for receiving engine exhaust gas, the exhaust passage having a mixing region comprising a first portion upstream of a second portion, the second portion comprising an exterior wall having a continuous helical trough depressed onto the exterior wall and wrapping around the second portion, the trough formed as an inwardly-protruding indentation traversing at least once around the exhaust passage in a coiled path angled with respect to a cross-section of the exhaust passage, the exterior wall defining an interior passage configured to receive the engine exhaust gas and redirect the engine exhaust gas via the inwardly-protruding indentation, the inwardly-protruding indentation comprising an inner surface facing the interior passage and an outer surface opposite the inner surface, the inwardly-protruding indentation further comprising a first terminal end where exhaust gas first impinges on the inner surface and a second terminal end where exhaust gas lastly impinges on the inner surface, each of the first terminal end and the second terminal end located on a same side of the exhaust passage and aligned along a same axis of the mixing region, and the mixing region further comprising a rounded transition between a surface of the exterior wall upstream of the trough and the first terminal end of the inwardly-protruding indentation, the rounded transition extending along an entirety of the trough from the first terminal end to the second terminal end.