US Patent 10047705 Systems and methods for reducing vehicle evaporative emissions

Methods and systems are provided for managing fuel vapor in a vehicle evaporative emissions system configured with a fuel vapor canister for capturing and storing vapors from a vehicle fuel tank. In one example, a three-way valve is positioned between the fuel vapor canister and atmosphere, and may function during engine-off conditions to direct fuel tank vapors through the fuel vapor canister where they may be adsorbed, and then to an intake manifold of the engine where a second adsorbent for capturing and storing fuel vapors is positioned. In this way, fuel vapors that are not adsorbed by the fuel vapor canister, or fuel vapors that are freed from the canister during engine-off conditions may be routed to the second adsorbent prior to exiting to atmosphere, thus reducing undesired bleed emissions.