Method and system for fuel vapor control
AssigneeFord Global Technologies, LLC
InventorsRussell Randall Pearce, Mark W. Peters, Aed M. Dudar, Dennis Seung-Man Yang
Life of this patent
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Abstract
Methods and systems are provided for identifying leaks on each of a fuel tank and a canister side of a fuel system using a single leak check module. A position of a switching valve coupled in the vapor line of the fuel system is adjusted to selectively couple the leak check module to either the fuel tank or the canister. Leak is detected based on a change in pressure at a reference orifice of the leak check module following applying of vacuum from a vacuum pump.
Claims20
A method, comprising:
- indicating leakage on a canister side of a fuel system based on a first change in pressure at a reference orifice following applying of vacuum to the fuel system with an isolation valve closed;
- and
- indicating leakage on a fuel tank side of the fuel system based on a second change in pressure at the reference orifice following applying of vacuum to the fuel system with the isolation valve open.
A method for a fuel system coupled to an engine, comprising:
- operating in a first mode with a switching valve in a first position to detect leakage on a first, canister side of the fuel system;
- and
- operating in a second mode with the switching valve in a second position to detect leakage on a second, fuel tank side of the fuel system.
A fuel system, comprising:
- an engine;
- a fuel tank;
- a canister for storing fuel vapors;
- an isolation valve coupled in a vapor line between the fuel tank and the canister;
- a leak check module including a reference orifice, a vacuum pump, and a pressure sensor;
- a switching valve coupled along a vent of the canister, the switching valve selectively couplable to the fuel tank or the canister;
- and
- a controller with computer readable instructions for:
- in response to leak detection conditions being met,
- closing the isolation valve;
- actuating the switching valve to a first position to selectively couple the leak check module to the canister;
- operating the vacuum pump to apply vacuum to the canister;
- and
- indicating a canister leak but not a fuel tank leak based on a first change in pressure at the reference orifice following the applying of vacuum being larger than a first threshold.
Dependencies are inferred from the claim text.