US Patent 9416709 Coking resistant after-treatment dosing value

A dosing valve for administering a reducing agent into an exhaust stream within an exhaust manifold of an internal combustion engine. The dosing valve includes a valve needle internally coaxial to a valve body and held in a closed position by a force of compressed spring acting axially and held in relation to the valve needle and valve body. The negative impact of varnish and dehydrogenated compounds, or coking products, of hydrocarbon based reducing agents, is substantially reduced or eliminated. Additionally, this includes decreased sensitivity to the negative impact of the precipitates and crystals that come out of the solution due to temperature change with urea-based reducing agents.