Patent ID: 8916100

Claim:
A reducing agent aqueous solution mixing device for adding a reducing agent aqueous solution to an exhaust gas, the reducing agent aqueous solution mixing device being adapted to be disposed between a filter for trapping particulate substance in the exhaust gas and a reducing catalyst unit for reducing and purifying nitrogen oxide in the exhaust gas, the reducing agent aqueous solution mixing device comprising: an exhaust pipe including an elbow part having a curved portion, and a linear part disposed on an exhaust downstream side of the elbow part; an injector disposed outside the curved portion of the elbow part, the injector being configured to inject the reducing agent aqueous solution into the elbow part towards the linear part; a mixing pipe having a plurality of openings on an outer peripheral surface thereof, the mixing pipe being disposed inside the elbow part to enclose a surrounding of the reducing agent aqueous solution injected from the injector, an exhaust downstream side outlet portion of the mixing pipe being spaced apart from an inner wall of the exhaust pipe; an inner pipe spaced apart from the inner wall of the exhaust pipe in the linear part, the inner pipe being configured to allow the exhaust gas to flow through an inside thereof and arranged to allow the exhaust gas to flow through a space between an outer periphery of the inner pipe and the inner wall of the exhaust pipe, the inner pipe being a separate member from the mixing pipe and arranged such that a space exists between an exhaust upstream side inlet portion of the inner pipe and the exhaust downstream side outlet portion of the mixing pipe; and a flow section formed between the outlet portion of the mixing pipe and the inner wall of the exhaust pipe to direct the exhaust gas from an outer periphery of the mixing pipe to the inside of the inner pipe.