On-board refueling vapor recovery system with vent line check valve

Abstract

An on-board refueling vapor recovery system includes a shutoff mechanism that closes a first vapor path between the fuel tank and the filler cup when liquid fuel in the tank reaches a predetermined level and a vent line closure that closes a second vapor path between the canister and the filler cup, wherein closure of the first vapor path and the second vapor path reduces pressure in the filler cup to induce shutoff of a fuel nozzle.

1 . An on-board refueling vapor recovery system, comprising:
 a fuel tank;   a canister;   a filler cup having a mechanical seal disposed therein to form a seal around a filler nozzle during refueling;   a vent line connecting the canister and the filler cup;   a shutoff mechanism that closes a first vapor path between the fuel tank and the filler cup when liquid fuel in the tank reaches a predetermined level; and   a vent line closure that closes a second vapor path between the canister and the filler cup, wherein the vent line closure closes in response to a pressure change caused by closure of the shutoff mechanism, and wherein closure of the first vapor path and the second vapor path reduces pressure in the filler cup to induce shutoff of a fuel nozzle.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . The system of  claim 1 , wherein the shutoff mechanism is a fuel limit vent valve. 
     
     
         6 . The system of  claim 1 , wherein the shutoff mechanism is a recirculation line having one end that is closed by the liquid fuel when the liquid fuel reaches a full level. 
     
     
         7 . The system of  claim 1 , wherein the vent line closure is a check valve disposed in the vent line between the canister and the filler cup. 
     
     
         8 . The system of  claim 7 , wherein the check valve is a pressure responsive valve that closes in response to a pressure differential across the check valve caused by closure of the shutoff mechanism. 
     
     
         9 . (canceled) 
     
     
         10 . A method of restricting vapor flow in an on-board refueling vapor recovery system with a fuel tank, a canister, a filler cup having a mechanical seal disposed therein to form a seal around a filler nozzle during refueling, and a vent line connecting the canister and the filler cup, the method comprising:
 closing a first vapor path between the fuel tank and the filler cup when liquid fuel in the tank reaches a predetermined level; and   closing a second vapor path between the canister and the filler cup, wherein the second vapor path is closed in response to a pressure change caused by closure of the first vapor path, and wherein closure of the first vapor path and the second vapor path reduces pressure in the filler cup to induce shutoff of a fuel nozzle.   
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The method of  claim 10 , wherein the step of closing the second vapor path comprises closing a pressure responsive valve in response to a pressure differential across a check valve caused by closure of the shutoff mechanism.