On Board Refueling Vapor Recovery (ORVR) System: Description
From the beginning of refueling, the fuel tank pressure goes up. When the pressure reaches the setting value of the Refueling Control Valve (RCV) opening pressure, the RCV is opened. After RCV opens, the air and vapor inside the fuel tank go through refueling EVAP vapor cut valve, RCV and refueling vapor line to the EVAP canister. The vapor is absorbed by the EVAP canister and the air is released to the atmosphere. When the refueling has reached the full level of the fuel tank, the refueling EVAP vapor cut valve is closed and refueling is stopped because of auto shut-off. The vapor which was absorbed by the EVAP canister is purged during driving. The RCV is always closed during driving and the evaporative emission control system is operated the same as a conventional system. See Fig 1.