Canister purge strategy for a hybrid electric vehicle

摘要

The present invention provides a method and system for purging a vapor canister in a Hybrid Electric Vehicle during vehicle idle conditions. The present invention first determines whether purging is necessary by measuring fuel tank pressure and the time since the last purge. If either of these elements exceeds a calibratable threshold, the controller determines that the engine needs to be on and that purging must occur. An electronic throttle controller can also be used to command the throttle plate to low positions to increase intake manifold vacuum while purging. This allows for very rapid ingestion of the fuel vapor without risk of engine stalls, if used in an HEV where the engine speed is controlled by an electric motor. Upon completion of the purging process, the engine is shut "off" and the vehicle is returned to its normal idle conditions.