Gm Global Technolgoy Operations, Inc.

S Raghuma Reddy

Roy A Giacomazzi

Gregory E Rich

A fuel vapor storage canister to prevent breakthrough evaporative emission loss and facilitate purging by concentrating the fuel vapor close to the vent to the engine. The canister is divided into two compartments which communicate through a connective means that only allows vapor into the second compartment when a control valve, located in the connective means, opens at a threshold pressure.

Compartmental evaporative canister and pressure control valve assembly

Vehicle tank pressure is controlled by adsorbing air from the tank in a zeolite bed, and passing fuel vapor back to the tank. The zeolite is later regenerated by application of heat and vacuum.

Vehicle fuel tank pressure control method

Warmed returned fuel from a vehicle fuel injection system is returned only a segregating canister in the tank, and pumped back therefrom preferentially, with make up fuel allowed in only as needed. Overall heating of the stored fuel, and consequent running losses, are substantially reduced, with no ill effects on vehicle operation.

Vehicle fuel system with reduced tank heating

An improved evaporative emission control system uses a charcoal canister, but, rather than air purging the canister of stored vapors, desorbs them, substantially without air, by application of a vaccum and reabsorbs the purged vapors into the liquid fuel in the tank. Any effect on driveability and exhaust emissions is thereby avoided, and canister capacity and efficiency are increased.

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West Bloomfield, MI, United States of America

S Raghuma Reddy