Reductant aqueous solution mixing device and exhaust aftertreatment device provided with the same

A reductant aqueous solution mixing device interposed between a filter device that captures particulate matters in an exhaust gas and a selective catalytic reduction device disposed downstream of the filter device, the reductant aqueous solution mixing device adding a reductant aqueous solution in the exhaust gas, and the reductant aqueous solution mixing device comprising:

• an elbow pipe attached to an outlet pipe of the filter device, the elbow pipe changing a flow direction of the exhaust gas flowing from the filter device;
• a straight pipe connected to a downstream side of the elbow pipe, the straight pipe extending in a direction intersecting an axial line of the outlet pipe of the filter device;
• and
• an injector attached to the elbow pipe, the injector injecting the reductant aqueous solution into an inside of the elbow pipe toward the straight pipe, wherein:
• the elbow pipe comprises:
• an inlet connected to the outlet pipe of the filter device;
• an outlet connected to the straight pipe;
• a direction-changing section provided between the inlet and the outlet, the direction-changing section changing the flow direction of the exhaust gas introduced from the inlet toward the outlet;
• and
• an injector attachment on which the injector is attached, the injector attachment being provided outside the direction-changing section, and the injector attachment being offset so that a reductant aqueous solution introduction port of the injector is located closer to the outlet relative to a part of the inlet most remote from the outlet,
• the direction-changing section comprises a first bulging portion provided by outwardly bulging a part of the direction-changing section opposite to the injector attachment,
• the first bulging portion is provided between an outlet end of the outlet pipe of the filter device and an inlet end of the straight pipe,
• a mixing pipe comprising an axial first end supported by an inner wall of the injector attachment and an axial second end opened toward the straight pipe is provided inside the elbow pipe, and
• a part of the first bulging portion facing a region of the mixing pipe from the first end to a central portion curves outward and a part facing a region of the mixing pipe from the central portion to the second end extends inward.