System for Evaporative and Refueling Emission Control for a Vehicle

Abstract

A fuel tank evaporative emissions control and diagnostic system includes a fuel tank, a canister in fluid communication with the fuel tank to receive vapor escaping from the fuel tank, at least one isolation valve positioned between the fuel tank and the canister, a pressure sensor in fluid communication with the canister, a purge valve positioned between the canister and an internal combustion engine to be in fluid communication with the canister and the internal combustion engine, a canister vent valve positioned on an air inlet of the canister for allowing air to purge vapor from the canister to exit the and into the internal combustion engine, and one or more electronic controllers coupled to the pressure sensor, the isolation valve, the purge valve, and the canister vent valve for controlling the valves according to a preset diagnostic test for checking for malfunctions in the system.

1 - 20 . (canceled) 
     
     
         21 . A method for performing vehicle emission control diagnostics, the method comprising:
 selectively opening and closing first and second diurnal control valves situated along a vapor line extending between a fuel tank and an evaporation canister of a fuel system of the vehicle;   selectively opening and closing a canister vent valve of the fuel system, the canister vent valve configured to control an inlet line of the evaporation canister;   selectively opening and closing a purge valve of the fuel system situated on a purge line extending between an outlet of the evaporation canister and an internal combustion engine of the vehicle;   utilizing a pressure sensor of the fuel system situated between the first and second diurnal control valves to measure a pressure change resulting from the selective opening and closing of the first and second diurnal control valves, the canister vent valve, and the purge valve; and   determining whether a malfunction of the fuel system exists based on the pressure change.   
     
     
         22 . The method of  claim 21 , further comprising performing the method while the internal combustion engine is running. 
     
     
         23 . The method of  claim 21 , further comprising performing the method after a cold start of the internal combustion engine. 
     
     
         24 . The method of  claim 21 , further comprising performing the method during a refueling of the fuel tank. 
     
     
         25 . The method of  claim 21 , wherein the first and second diurnal control valves are selectively opened and closed to determine whether a malfunction of the pressure sensor exists. 
     
     
         26 . The method of  claim 21 , wherein the first diurnal control valve is opened and the second diurnal control valve is closed to determine whether a malfunction of the fuel tank exists. 
     
     
         27 . The method of  claim 21 , wherein the first diurnal control valve is closed, the second diurnal control valve is opened, and the purge valve is closed during a purge of the evaporation canister to determine whether a malfunction of the evaporation canister exists. 
     
     
         28 . The method of  claim 27 , wherein the pressure change is a pressure degradation. 
     
     
         29 . The method of  claim 21 , wherein the first diurnal control valve is closed, the second diurnal control valve is opened, the canister vent valve is closed, and a manifold vacuum is applied to the outlet of the evaporation canister to determine whether a malfunction of the evaporation canister exists. 
     
     
         30 . The method of  claim 29 , wherein the pressure change is a vacuum degradation. 
     
     
         31 . A vehicle comprising:
 an internal combustion engine;   a fuel system including a fuel tank, an evaporation canister, first and second diurnal control valves situated on a vapor line extending between the fuel tank and the evaporation canister, a pressure sensor situated between the first and second diurnal control valves, a canister vent valve configured to control an inlet line of the evaporation canister, and a purge valve situated on a purge line extending between the evaporation canister and the internal combustion engine; and   a control module coupled to the fuel system, the control module configured to:
 selectively open and close the first and second diurnal control valves; 
 selectively open and close the canister vent valve; 
 selectively open and close the purge valve; 
 utilize the pressure sensor to measure a pressure change resulting from the selective opening and closing of the first and second diurnal control valves, the canister vent valve, and the purge valve; and 
 determine whether a malfunction of the fuel system exists based on the pressure change. 
   
     
     
         32 . The vehicle of  claim 31 , wherein the control module determines the malfunction while the internal combustion engine is running. 
     
     
         33 . The vehicle of  claim 31 , wherein the control module determines the malfunction after a cold start of the internal combustion engine. 
     
     
         34 . The vehicle of  claim 31 , the control module determines the malfunction during a refueling of the fuel tank. 
     
     
         35 . The vehicle of  claim 31 , wherein the first and second diurnal control valves are selectively opened and closed while the canister vent valve is closed and the purge valve is closed to determine whether a malfunction of the pressure sensor exists. 
     
     
         36 . The vehicle of  claim 31 , wherein the first diurnal control valve is opened and the second diurnal control valve is closed to determine whether a malfunction of the fuel tank exists. 
     
     
         37 . The vehicle of  claim 31 , wherein the first diurnal control valve is closed, the second diurnal control valve is opened, and the purge valve is closed during a purge of the evaporation canister to determine whether a malfunction of the evaporation canister exists. 
     
     
         38 . The vehicle of  claim 37 , wherein the pressure change is a pressure degradation. 
     
     
         39 . The vehicle of  claim 31 , wherein the first diurnal control valve is closed, the second diurnal control valve is opened, the canister vent valve is closed, and a manifold vacuum is applied to the outlet of the evaporation canister to determine whether a malfunction of the evaporation canister exists. 
     
     
         40 . The vehicle of  claim 39 , wherein the pressure change is a vacuum degradation.