Fuel tank pressure relief valve cleaning
AssigneeFord Global Technologies, LLC
InventorsMark W. Peters, Robert Roy Jentz, Aed M. Dudar, Matthew Werner
Life of this patent
Estimating the term…
Abstract
Methods and systems for cleaning a pressure relieve valve for a fuel tank are disclosed. In one example approach a method for cleaning a pressure relief valve that is normally activated at a preset negative pressure in a fuel system comprises, during a test cycle, reducing fuel system pressure to a predetermined pressure which is higher than the preset pressure, and measuring pressure changes in the fuel system; and when not in the test cycle, periodically reducing the fuel system pressure to a third pressure which is less than said preset pressure.
Claims20
A method for cleaning a pressure relief valve that is normally activated at a preset negative pressure in a fuel system, comprising:
- during a test cycle, reducing fuel system pressure to a predetermined pressure which is higher than the preset pressure, and measuring pressure changes in said fuel system;
- and
- when not in said test cycle, periodically reducing said fuel system pressure to a third pressure which is less than said preset pressure.
A method for cleaning a pressure relief valve that is normally activated at a preset negative pressure in a fuel system, comprising:
- during a diagnostic test, reducing fuel system pressure to a predetermined pressure which is higher than the preset pressure, measuring pressure changes in said fuel system, and indicating a fault when said measurements exceed a threshold;
- and
- when not performing said diagnostic test, periodically reducing said fuel system pressure to a third pressure which is less than said preset pressure to force the relief valve open even when stuck closed.
A method for performing operations on a fuel vapor system having a vapor absorbing canister coupled between a fuel tank and an engine intake via a purge valve, and a pressure relief valve which opens at a preset negative pressure to limit maximum negative pressure in the fuel vapor system, comprising:
- a vapor purge operation purging fuel vapors from the fuel vapor system into the engine intake manifold by operating the purge valve;
- a test operation reducing fuel system pressure to a predetermined pressure which is higher than the preset pressure, measuring pressure changes in said fuel system, and indicating a fault when said measurements exceed a threshold;
- and
- a pressure relief valve cleaning operation reducing said fuel system pressure to a third pressure which is less than said preset pressure to force the relief valve open even when stuck closed.
Dependencies are inferred from the claim text.