Importance

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Abstract

A vapor vent valve (16) comprises a housing (28) the interior of which is divided into two fluid chambers (32, 34) by a movable wall (30). The first chamber (32) provides a closable junction in the vapor recovery passageway (18, 20) between a liquid fuel tank (10) and a vapor storage canister (22). The second chamber (34) has a combined inlet/outlet (38) which is interconnected with a signal pressure region (44) in the fuel tank fill tube (12) adjacent to the fill tube cap (14). A valve plug (36) is fixed to the movable wall (30) so that when the pressure in the first fluid chamber (32), the signal pressure region (44 ) and the second fluid chamber (32) are substantially equivalent, the valve plug (36) is positioned to close the vapor recovery passageway (18, 20). When the closure cap (14) is removed, a fill nozzle (46) is inserted into the fill tube (12 ), and liquid fuel is being delivered into the fuel tank (10), the pressure in the signal pressure region (44) and the second fluid chamber (32) decreases relative to that in the tank (10) and the first fluid chamber (34), the movable wall (30) is displaced from its normal position causing the valve plug (36) to open the vapor recovery passageway (18, 20) between the fuel tank (10) and the vapor storage canister (22).

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First Claim