Fuel system control

Patent metadata

Field	Value
Publication number	US-2016201614-A1
Application number	US-201615074331-A
Country	US
Kind code	A1
Filing date	Mar 18, 2016
Priority date	Feb 21, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

Methods are provided for reliving excess vacuum from a fuel tank. In response to elevated fuel tank vacuum levels, a canister purge valve is opened to dissipate the vacuum to an engine intake manifold while the engine is not combusting. Alternatively, the purge valve is opened to dissipate the excess vacuum to the intake manifold while the engine is combusting during conditions when the likelihood of air-fuel ratio errors are lower or when any incurred errors are better tolerated.

First claim

1 . A method for a fuel system coupled to an engine, comprising:
in response to fuel tank vacuum level, opening a canister purge valve to dissipate excess fuel tank vacuum into an engine intake manifold while the engine is not combusting, a timing of the opening based on engine operating conditions.

2 . The method of claim 1 , wherein in response to fuel tank vacuum level includes one or more of in response to fuel tank vacuum level being higher than a threshold level and in response to a rise in fuel tank vacuum level being higher than a threshold rate.

3 . The method of claim 2 , wherein the fuel system is coupled in a hybrid electric vehicle, and wherein the timing of opening based on engine operating conditions includes opening the canister purge valve at a timing based on a hybrid electric vehicle mode of operation.

4 . The method of claim 3 , wherein an indication that the fuel tank vacuum level is higher than the threshold level is received while the hybrid electric vehicle is in an engine mode of operation, and wherein opening the canister purge valve at a timing based on a hybrid electric vehicle mode of operation includes opening the canister purge valve after shifting the vehicle from the engine mode to a battery mode of operation.

5 . The method of claim 2 , wherein the engine is selectively deactivatable in response to idle-stop conditions, wherein the timing of opening based on engine operating conditions includes opening the canister purge valve after selectively deactivating the engine, and wherein selectively deactivating the engine includes selectively deactivating engine fuel injectors.

6 . The method of claim 5 , wherein an indication that the fuel tank vacuum level is higher than the threshold level is received while the engine is combusting and opening the canister purge valve after selectively deactivating the engine includes opening the canister purge valve while the engine is spinning to rest unfueled, or while the engine is at rest.

7 . The method of claim 1 , wherein the fuel system does not include a pressure relief valve.

8 . The method of claim 2 , wherein opening the canister purge valve includes transiently opening the canister purge valve until the fuel tank vacuum level is lower than the threshold level, and then closing the canister purge valve and resuming engine combustion.

9 . A method for a fuel system coupled to an engine in a hybrid electric vehicle, comprising:
in response to fuel tank vacuum being higher than a threshold level when the vehicle is operating in an engine mode, opening a canister purge valve to dissipate excess fuel tank vacuum to an engine intake when the vehicle is operating in a battery mode.

10 . The method of claim 9 , further comprising, in response to the fuel tank vacuum being higher than the threshold level, and before opening the canister purge valve, shifting the vehicle from the engine mode of operation to the battery mode of operation.

11 . A method for a fuel system coupled to an engine having selectively deactivatable fuel injectors, comprising:
in response to fuel tank vacuum being higher than a threshold level while the engine is combusting, selectively deactivating the engine and opening a canister purge valve to dissipate excess fuel tank vacuum after the deactivation.

12 . The method of claim 11 , wherein selectively deactivating the engine includes selectively deactivating engine fuel injectors.

13 . The method of claim 11 , wherein opening the canister purge valve to dissipate excess fuel tank vacuum after the deactivation includes opening the canister purge valve while the engine is spinning to rest unfueled or after the engine has spun to rest.

14 - 20 . (canceled)

Assignees

• Ford Global Tech Llc

Inventors

• Jentz Robert Roy
• Mullins John
• Dudar Aed M
• Peters Mark W

Classifications

• F02M25/0854

  Details of the absorption canister · CPC title

• F02M25/0836 Primary

  Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold · CPC title

• F02M25/0872

  Details of the fuel vapour pipes or conduits · CPC title

• F02M37/0064

  for engines being fed with multiple fuels or fuels having special properties, e.g. bio-fuels; varying the fuel composition (controlling engines working with pluralities of fuels F02D19/06) · CPC title