High-pressure fuel tanks may use an isolation valve to open and close a vapor path between the fuel tank and a purge canister. In a typical evaporative emissions system, vented vapors from the fuel system are sent to a purge canister containing activated charcoal, which adsorbs fuel vapors. During certain engine operational modes, with the help of specifically designed control valves (e.g., vapor vent valves), the fuel vapors are adsorbed within the canister. Subsequently, during other engine operational modes, and with the help of additional control valves, fresh air is drawn through the canister, pulling the fuel vapor into the engine where it is burned.
For high-pressure fuel tank systems, an isolation valve may be used to isolate fuel tank emissions and prevent them from overloading the canister and vapor lines. The isolation valve itself may be a normally closed valve that is opened to allow vapor flow for tank depressurization or any other event where vapor release is desired. The vapor flow rate may be controlled to, for example, prevent corking of vent valves elsewhere in the emissions system.
There is a desire for an isolation valve that can be used in high-pressure fuel tanks and that can depressurize quickly in a controlled manner to allow user access to the fuel tank within a reasonable amount of time.