US Patent 11773763 Dosing and mixing assemblies for exhaust aftertreatment system

A dosing and mixing assembly for an exhaust aftertreatment device includes a conduit arrangement defining overlapping, coaxial flow paths that join at a common flow path. The conduit arrangement defines a mixing region upstream of the overlapping, coaxial flow paths, an impact region at the overlapping, coaxial flow paths, and a merge region where the coaxial flow paths join. The outer of the coaxial flow paths insulates the inner of the flow paths at least as the impact region. Reactant can be dispensed into the inner flow path along a spray path that intersects the impact region of the conduit arrangement. A spray protector can be provided at or upstream of the mixer to inhibit swirling of reactant at the doser nozzle.