EVAPORATIVE SYSTEM INTEGRITY MONITOR

摘要

An evaporative emission control and leak detection system for a vehicle is provided. The system includes an integrated valve module in fluid communication with a carbon canister and atmosphere. The module is arranged to vent the system wh en exposed to predetermined high negative and positive pressure conditions. The module includes a switch mechanism having a spring biasing member arranged to bias the switch mechani sm to an open position. The switch is operable to indicate when the system is in a lo w negative pressure condition. The switch also includes a negative pressure valve coupl ed to a fluid passage between the canister, the atmosphere and the switch, and a positive pressure valve coupled to a fluid passage between the canister and atmosphere that bypasses the negative pressure valve and switch. The negative and positive pressure valves are positioned in a stacked arrangement in the integrated valve module.