Method and system for controlling liquid fuel and vapor flow during refueling of a motor vehicle fuel tank

A method of controlling flow of liquid fuel and fuel vapor during refueling from a dispensing nozzle of a vehicle fuel tank having a filler tube comprising:

• (a) disposing a fuel vapor vent valve with the tank and communicating the valve inlet with the vapor dome in the interior of the tank and communicating the vent valve outlet to a fuel vapor storage device;
• (b) disposing a seal in the filler tube for sealing about the dispensing nozzle upon insertion in the filler tube;
• (c) recirculating fuel vapor to the filler tube at a location downstream of the nozzle seal;
• and,
• (d) sizing a neck portion of the filler tube for effecting a dynamic seal between the inner surface of the said neck portion and fuel discharging from the nozzle.

A system for controlling flow of liquid fuel and vapor during refueling from a refueling nozzle of a motor vehicle fuel tank with a filler tube comprising:

• (a) a vent valve disposed in the tank wall and having an inlet communicating with the vapor dome in the tank and an outlet communicating with a remote vapor storage device;
• (b) a one-way valve operatively connected to admit vapor to the filler tube from the first conduit;
• (c) a reduced portion of said filler tube downstream of the location at which said one-way valve is connected to the filler tube, said reduced portion sized for effecting a dynamic seal with fuel discharging from the nozzle;
• and,
• (d) a seal about said nozzle disposed upstream.