Patent ID: 6499472
Filing Date: 2002-12-31
Classification: F16K

Abstract:
A method of operating a fuel tank isolation valve and a canister vent valve, the fuel tank isolation valve having a first port in fluid communication with a fuel vapor collection canister, a second port in fluid communication with a fuel tank, and an electric actuator moving a valve body to control fluid communication between the first and second ports, the canister vent valve controlling ambient fluid flow with respect to the fuel vapor collection canister, the method comprising:supplying a first electric signal to the electric actuator such that the valve body permits substantially unrestricted fuel vapor flow between the first and second ports; supplying a second electric signal to the electric actuator such that the valve body substantially prevents fuel vapor flow between the first and second ports; supplying a third electric signal to the electric actuator such that the valve body provides restricted fuel vapor flow between the first and second ports; and supplying a fourth electric signal to the canister vent valve to permit ambient fluid flow into the fuel vapor collection canister, the supplying of the fourth electric signal coinciding with the supplying the second electric signal.