Detection of a Humidity Sensor Failure in an Internal Combustion Engine

• US 20070181111A1
• Filed: 03/21/2007
• Published: 08/09/2007
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Motor Company
• Inventors: Cullen, Michael
• Granted Patent: US 7,398,775 B2
• Time in Patent Office: Days
• US Class Current: 123/677
• CPC Class Codes: F02D 13/0207 changing valve lift or valve lift and timing
• CPC Class Codes: F02D 13/0219 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 41/0047 Controlling exhaust gas recirculation [EGR] temperature control with cooler in recirculation circuit F02M26/33
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/1475 Regulating the air fuel ratio at a value other than stoichiometry
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02M 26/46 for determining the characteristics of gases, e.g. composition
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A system and method for utilizing a humidity sensor with an internal combustion engine of a vehicle is described. Specifically, information from the humidity sensor is used to adjust a desired air-fuel ratio to reduce engine misfire while improving vehicle fuel economy. Further, such information is also used to adjust timing and/or lift of the valve in the engine cylinder. Finally, diagnostic routines are also described.

Claims

1-9. -9. (canceled)

10. A method to determine degradation of a humidity sensor used for controlling an engine of a vehicle, the humidity sensor exterior to a passenger compartment of the vehicle, the method comprising:

determining whether to enable monitoring of the sensor based on a duration since vehicle operation; and

in response to a determination to enable monitoring,

comparing a signal from a second humidity sensor to a signal from the humidity sensor exterior to said passenger compartment of the vehicle to determine whether either of sensors has degraded.

11. The method of claim 10 further comprising using default setting for engine actuators in response to a determination that said exterior sensor has degraded.

12. The method of claim 10 further comprising using default setting for an amount of exhaust gas recirculation in response to a determination that said exterior sensor has degraded.

13. The method of claim 10 wherein said duration since engine operating includes a time since a key-on engagement.

14. The method of claim 10 wherein said second sensor is located exterior to said passenger compartment of the vehicle.

15. A method to determine degradation of a humidity sensor used for controlling an engine of a vehicle, the humidity sensor exterior to a passenger compartment of the vehicle, the method comprising:

determining whether to enable monitoring of the sensor based on an engine off duration; and

in response to a determination to enable monitoring,

comparing a signal from a humidity sensor interior to a passenger compartment of the vehicle to a signal from the humidity sensor exterior to said passenger compartment of the vehicle to determine whether either of said interior or exterior sensor has degraded.

16. The method of claim 15 further comprising using default setting for engine actuators in response to a determination that said exterior sensor has degraded.

17. The method of claim 15 further comprising using default setting for an amount of exhaust gas recirculation in response to a determination that said exterior sensor has degraded.

18. The method of claim 15 wherein said interior humidity sensor is used to control a climate in said passenger compartment of the vehicle.

19. The method of claim 18 wherein said interior humidity sensor is used to control a clutch coupled to a compressor in an air-conditioning system of the vehicle.