AIR DRIVEN REDUCTANT DOSING SYSTEM

摘要

A dosing system for delivering reductant into an exhaust gas treatment system of an internal combustion engine using an air driven hydraulic pump, which includes a pressure pump tank and a liquid supply tank, for closed-loop controlling reductant pressure, and a three-stage PWM control method for dosing rate control. Reductant residue in the dosing system is purged by using compressed air, and when the air driven hydraulic pumps is positioned inside a reductant tank, heating means in the reductant tank can also be used for heating the air driven hydraulic pump. The closed-loop pressure control together with the three-stage PWM control allow dosing accuracy insensitive to pressure variations in compressed air, thereby a variety of compressed air sources can be used.

主权项

1. An apparatus for delivering reductants into an exhaust gas system of an internal combustion engine comprising:
a reductant tank; a compressed air source; a liquid supply tank having a first inlet port fluidly coupled to said reductant tank through a check valve, a second inlet port fluidly coupled to said compressed air source, a first outlet port for releasing compressed air from said liquid supply tank, and a second outlet port for reductant inside said liquid supply tank to flow out; a pressure pump tank comprising a liquid inlet port fluidly coupled to said second outlet port of said liquid supply tank through a check valve, and a liquid outlet port; an injector with a reductant inlet fluidly coupled to said liquid outlet port of said pressure pump tank for controlling reductant flow rate to said exhaust gas system; a pressure control means controlling air flow to said liquid supply tank configured to control reductant pressure in said liquid supply tank by refilling air to said liquid supply tank through said second inlet port, and releasing air through said first outlet port, and a dosing rate control means configured to energize open said injector for a period of time in a periodically repeating cycle in releasing reductant to said exhaust gas system.