Evaporative emission system integrity module

摘要

An evaporative emission control and leak detection system for a motor vehicle is provided. The system is in fluid communication with a fuel tank, an engine, and a carbon canister and includes an integrated valve module that is in fluid communication with the carbon canister and the atmosphere. The module provides for venting of the system when exposed to predetermined high negative and positive pressure conditions. The module includes a switch mechanism that is operable to indicate when the system is in a low negative pressure condition. The module further includes a one-way high negative pressure valve and a one-way high positive pressure valve coupled to a fluid passage that bypasses the high negative pressure valve and the switch. The high negative and high positive pressure valves are positioned in a stacked arrangement along a common axis in the valve module.