SYSTEMS AND METHODS FOR DISCERNING FUEL TANK PRESSURE TRANSDUCER DEGRADATION

• US 20170037806A1
• Filed: 08/05/2015
• Published: 02/09/2017
• Est. Priority Date: 08/05/2015
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Dudar, Aed M.
• Granted Patent: US 10,233,857 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F02D 41/003 Adding fuel vapours, e.g. drawn from engine fuel reservoir
• CPC Class Codes: F02D 41/0042 Controlling the combustible mixture as a function of the canister purging, e.g. control of injected fuel to compensate for deviation of air fuel ratio when purging
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0836 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 Class Codes: Y02T 10/40 Engine management systems

Abstract

A method for a fuel system is provided, wherein a fuel vapor canister is vented to an engine intake during a first condition, and wherein a restriction in a canister vent pathway is indicated, responsive to a change in a fuel tank pressure transducer output greater than a threshold. If the fuel tank pressure transducer output changes less than the threshold, degradation of the fuel tank pressure transducer is indicated. In this way, a fuel tank pressure transducer offset may be distinguished from a canister vent pathway restriction if a fuel tank pressure transducer indicates a significant pressure or vacuum in a fuel tank following a vehicle-off soak.

Claims

1. A method for a fuel system, comprising:

during a first condition, venting a fuel vapor canister to an engine intake; and

indicating a restriction in a canister vent pathway responsive to a change in a fuel tank pressure transducer output greater than a threshold.

2. The method of claim 1, further comprising:

updating one or more fuel system parameters responsive to an indication of a restriction in the canister vent pathway.

3. The method of claim 2, wherein the one or more fuel system parameters include a fuel canister purge schedule.

4. The method of claim 1, further comprising:

indicating degradation of a fuel tank pressure transducer responsive to a change in a fuel tank pressure transducer output less than a threshold.

5. The method of claim 4, further comprising:

updating one or more fuel system parameters responsive to an indication of degradation of a fuel tank pressure transducer.

6. The method of claim 4, wherein the first condition comprises:

a fuel tank pressure transducer output more than a threshold different from atmospheric pressure.

7. The method of claim 6, wherein the first condition follows a vehicle-off soak comprising a duration greater than a threshold.

8. The method of claim 7, wherein the vehicle-off soak further comprises a canister vent valve in an open conformation and a canister purge valve in a closed conformation.

9. The method of claim 7, wherein the first condition comprises a vehicle-on, engine-off condition.

10. The method of claim 7, wherein the first condition follows a first vehicle-on event following the vehicle-off soak.

11. A method for a fuel system, comprising:

responsive to a vehicle-off condition, maintaining a canister vent valve open and a canister purge valve closed for a vehicle-off soak;

following the vehicle-off soak, opening the canister purge valve responsive to a fuel tank pressure transducer output more than a threshold different from atmospheric pressure; and

indicating fuel tank pressure transducer degradation responsive to the fuel tank pressure transducer output failing to equilibrate to within a threshold of atmospheric pressure.

12. The method of claim 11, further comprising:

updating one or more fuel system parameters responsive to the indication of fuel tank pressure transducer degradation.

13. The method of claim 11, further comprising:

indicating a canister vent pathway restriction responsive to the fuel tank pressure transducer output equilibrating to within a threshold of atmospheric pressure.

14. The method of claim 11, wherein the canister purge valve is opened during a vehicle-on, engine-off condition following the vehicle-off soak.

15. The method of claim 11, further comprising:

indicating to execute a fuel tank pressure transducer offset test at a subsequent vehicle-off condition responsive to the vehicle-off soak having a duration less than a threshold.

16. The method of claim 11, further comprising:

following the vehicle-off soak, indicating that fuel tank pressure transducer integrity responsive to a fuel tank pressure transducer output within a threshold of atmospheric pressure.

17. A fuel system for a vehicle, comprising:

a fuel tank coupled to a fuel vapor canister;

a fuel tank pressure transducer coupled to the fuel tank;

an engine intake coupled to the fuel vapor canister via a canister purge valve;

a canister vent pathway coupling the fuel vapor canister to atmosphere via a canister vent valve; and

a controller configured with instructions stored in non-transitory memory, that when executed, cause the controller to;

responsive to a vehicle-off condition, maintain the canister vent valve open and the canister purge valve closed for a vehicle-off soak;

following the vehicle-off soak, open the canister purge valve responsive to a fuel tank pressure transducer output more than a threshold different from atmospheric pressure; and

indicate degradation of the fuel tank pressure transducer responsive to the fuel tank pressure transducer output failing to equilibrate to within a threshold of atmospheric pressure.

18. The fuel system of claim 17, wherein the controller is further configured with instructions stored in non-transitory memory, that when executed, cause the controller to:

indicate a canister vent pathway restriction responsive to the fuel tank pressure transducer output equilibrating to within a threshold of atmospheric pressure.

19. The fuel system of claim 18, wherein the controller is further configured with instructions stored in non-transitory memory, that when executed, cause the controller to:

following the vehicle-off soak, indicate that the fuel tank pressure transducer is intact responsive to a fuel tank pressure transducer output within a threshold of atmospheric pressure.

20. The fuel system of claim 19, wherein the controller is further configured with instructions stored in non-transitory memory, that when executed, cause the controller to:

indicate to execute a fuel tank pressure transducer offset test at a subsequent vehicle-off condition responsive to the vehicle-off soak having a duration less than a threshold.