Cold start fuel control system

摘要

A cold start fuel control system as provided for an internal combustion engine of the type having at least one combustion chamber, an intake manifold and a source of fuel. A fuel vapor canister has an interior chamber fluidly connected to the source of fuel and a normally closed shut-off valve fluidly connected between the canister and ambient air. A normally closed purge valve is then fluidly connected in series between the interior of the canister and the intake manifold. The system also includes a cold start fuel injector having an inlet connected to the fuel source and an outlet open to the intake manifold or, optionally, to the interior of the fuel vapor canister. During a cold start engine condition, fuel is supplied as needed from both the fuel vapor canister and cold start injector by activating the cold start injector and simultaneously opening the purge and shut-off valves in synchronism with the engine intake cycle(s). An air flow sensor measures the mass flow of the air/fuel mixture to the engine and provide an output signal to an electronic control unit which controls the activation of the cold start fuel injector and/or valves to achieve a stoichiometric or slightly lean air/fuel mixture. Additionally, secondary air is provided through the cold start fuel injector for enhancing the atomization of the fuel in the air from the cold start injector.