Patent ID: 8181446

Claim:
An exhaust emission purification apparatus for an engine, comprising: a reduction catalyst disposed in an exhaust passage of the engine; an addition device for adding a NOx reducing agent into the exhaust gas of the engine, the addition device including an injection nozzle disposed in the exhaust passage at a position upstream of the reduction catalyst, the addition device for injecting the NOx reducing agent via the injection nozzle; and a passage member interposed in the exhaust passage, the passage member forming an internal circumferential surface of at least a part of the exhaust passage between the injection nozzle and the reduction catalyst, wherein the passage member is joined by welding in an axial direction of the passage member into a hollow shape with the internal circumferential surface, and is disposed in the exhaust passage in a situation where the welding portion is located on the internal circumferential surface at a position where a normal line of the internal circumferential surface that is drawn at said position inclines vertically downward with respect to a horizontal direction extending from said position, wherein the passage member comprises, in the welding portion, a weld bead swelling on the internal circumferential surface.