Abstract: An exhaust gas aftertreatment unit includes a selective catalytic reduction device that treats engine exhaust gas, a connecting pipe that guides the engine exhaust gas to the reduction device, a reducing agent injection device disposed on the connecting pipe to inject a reducing agent into the exhaust gas, and a cooling water flowpath that guides cooling water to an internal flowpath of the injection device. The cooling water path includes a first flowpath joined with the internal flowpath, second and third flowpaths branching off from the first flowpath, and a branching point where the first flowpath branches into the second flowpath and the third flowpath is positioned higher than a connecting portion of the injection device and the first flowpath. The third flowpath extends further upward than the second flowpath from the branching point. The second and third flowpaths merge on an opposite side of the branching point.

Abstract: An exhaust gas aftertreatment unit includes a selective catalytic reduction device that treats engine exhaust gas, a connecting pipe that guides the engine exhaust gas to the reduction device, a reducing agent injection device disposed on the connecting pipe to inject a reducing agent into the exhaust gas, and a cooling water flowpath that guides cooling water to an internal flowpath of the injection device. The cooling water path includes a first flowpath joined with the internal flowpath, second and third flowpaths branching off from the first flowpath, and a branching point where the first flowpath branches into the second flowpath and the third flowpath is positioned higher than a connecting portion of the injection device and the first flowpath. The third flowpath extends further upward than the second flowpath from the branching point. The second and third flowpaths merge on an opposite side of the branching point.