Patent ID: 7908845

Claim:
A mixing apparatus mountable within a generally cylindrical passage defined by an exhaust gas conduit of an exhaust gas after-treatment system, the passage having an outer region and an inner region operable to convey an exhaust stream and a liquid stream, the mixing apparatus comprising: a retainer ring operable to retain the mixing apparatus within the passage, the retainer ring including a first portion that is coextensive with a first plane, a second portion that is coextensive with a second plane, and a third portion that is coextensive with a third plane; a first plurality of fins extending from said retainer ring and operable to impart a rotational velocity component in a first direction to at least one of the exhaust stream and liquid stream in the outer region of the passage; and a second plurality of fins extending from said retainer ring and operable to impart a rotational velocity component in a second direction, opposite said first direction, to at least one of the exhaust stream and liquid stream in the inner region of the passage; wherein the second plurality of fins includes a first fin extending from the first portion, a second fin extending from the second portion, and a third fin extending from the third portion; and wherein the first plane, second plane, and third plane define a triangle.