Image Number 2 for United States Patent #5964204.
A fuel vapor emission control system for an automobile includes a fuel filler pipe, a filler cap, a check valve, a fuel tank, a carbon canister or other vapor storage device, a reservoir, and a vapor tube for conducting fuel vapor from one or more tank vent valves located on the fuel tank. The system reduces the amount of vapor mass which exits the fuel tank to the carbon canister by condensing some of the vapor sent to the canister during refueling. Fuel entering the filler pipe is used as a condensing agent. The system also reduces the amount of vapor pumped to the vapor storage device during diurnal cycles by permitting the volume of the fuel tank to change in response to changes in pressure within the tank.