Vapor recovery fuel tank system

摘要

A vapor recovery fuel system includes a fuel tank having at least one vent opening defined therein. A fuel vapor canister is in communication with the vent opening to receive and filter fuel vapors from the tank. A refueling control valve is configured in the vent opening and has a first inlet orifice and an outlet in communication with the vapor trap. The control valve includes a variably buoyant first float body extending into an interior of the fuel tank which rises over a predetermined range of movement in response to increasing fuel level. The control valve includes a second float body engaged by the first float body over at least a portion of its range of movement. The first float body has a buoyancy during refueling so as to rise with increasing fuel level to engage and move the second float body into a sealing position to seal the inlet orifice from the outlet at a predetermined height of fuel within the tank. The first float body has a buoyancy reducing mechanism for automatically reducing its buoyancy after refueling so that it lowers in the fuel tank thereby allowing the second buoyant body to lower and unseal the inlet orifice after refueling.