Patent ID: 8069655

Claim:
A dosant delivery apparatus comprising: a fractionator disposed downstream from an engine exhaust manifold and operating to redirect a fraction of exhaust from the engine manifold; a flow-rate regulator disposed downstream from the fractionator and operating to control the flow of the fraction of exhaust redirected by the fractionator; a doser disposed downstream of the flow-rate regulator and operating to provision a supply of dosant in the path of the controlled flow of the fraction of exhaust; and a first exhaust redirection channel, the channel comprising an inlet and an outlet, the inlet disposed to redirect a fraction of exhaust from the engine exhaust manifold; wherein the flow-rate regulator is a stop, controlled by a solenoid, that opens and closes the first exhaust redirection channel; wherein the solenoid controls the stop, which is disposed to extend across and to retract from the inlet of the first redirection channel, the apparatus further comprising a second redirection channel also having an inlet, the inlets of the first and second redirection channels disposed to redirect fractions of exhaust from the engine exhaust manifold, the first and second redirection channels also comprising an outlet; and wherein the solenoid controls the stop, which also is disposed to extend across and to retract from the inlet of the second redirection channel.