The flow of exhaust gas flowing through the SCR muffler becomes good, thus improving the efficiency of purging nitrogen oxide (NOx) contained in exhaust gas. Further, vibrations that are caused by vibrations of the vehicle, exhaust gas, and the like, to which a reducing agent, etc., supplying nozzle is subject, are suppressed or reduced, thus improving the efficiency of an SCR catalyst purging nitrogen oxide (NOx) and the durability of the reducing agent, etc., supplying nozzle. The SCR muffler comprises an SCR catalyst 1 for selectively reducing and purging nitrogen oxide (NOx) contained in exhaust gas; an exhaust pipe 2 that allows the exhaust gas to flow into the SCR catalyst; and a reducing agent, etc., supplying means 3 that supplies a reducing agent or a reducing agent precursor to the exhaust gas. A plate 4 having air holes 5 which disperse and make a flow of the exhaust gas uniform is provided downstream of the reducing agent, etc., supplying means and upstream of the SCR catalyst. The air holes 5 are arranged in only an area greater in diameter than the exhaust pipe and in a staggered fashion so as to form concentric circles. Further, the reducing agent, etc., supplying nozzle 30 as the means 3 is inserted through a plate 40 having air holes 5 , and the plate is held in the exhaust pipe.
1. An SCR muffler which comprises:
an SCR catalyst for selectively reducing and purging nitrogen oxide (NOx) contained in exhaust gas;
an exhaust pipe that allows the exhaust gas to flow into the SCR catalyst and has air holes in its portion to be inserted into the muffler; and
a reducing agent supplying means that supplies a reducing agent or a reducing agent precursor to the exhaust gas,
characterized in that a plate having air holes which disperse and make a flow of the exhaust gas uniform is attached to an end of the exhaust pipe and greater in diameter than the exhaust pipe, and the air holes are arranged only in an area outside the diameter of the exhaust pipe, and in that the plate has a cross section shaped like a convex tapering upstream only in an area within the diameter of the exhaust pipe.