HUMIDITY SENSOR DIAGNOSTICS

• US 20140238370A1
• Filed: 02/22/2013
• Published: 08/28/2014
• Est. Priority Date: 02/22/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Pursifull, Ross Dykstra, Makki, Imad Hassan, Clark, Timothy Joseph, Uhrich, Michael James, Kumar, Pankaj
• Granted Patent: US 9,482,172 B2
• Time in Patent Office: Days
• US Class Current: 123/690
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 2200/0611 Fuel type, fuel composition or fuel quality
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Embodiments for diagnosing a humidity sensor are provided. One example method comprises adjusting an engine operating parameter based on humidity of a first gas flow measured by a humidity sensor, and indicating degradation of the humidity sensor if a humidity of a second gas flow measured by the humidity sensor is different than an expected humidity. In this way, degradation of the humidity sensor may be indicated if the humidity of the second gas flow measured by the humidity sensor is different than expected.

Claims

1. A method, comprising:

adjusting an engine operating parameter based on humidity of a first gas flow measured by a humidity sensor; and

indicating degradation of the humidity sensor if a humidity of a second gas flow measured by the humidity sensor is different than an expected humidity.

2. The method of claim 1, wherein the first gas flow comprises air from an engine air intake system.

3. The method of claim 2, wherein the second gas flow comprises air from an engine intake manifold, and wherein the expected humidity is a function of fuel composition and an amount of exhaust gas recirculated from an engine exhaust to the engine intake manifold.

4. The method of claim 2, wherein the second gas flow comprises exhaust gas recirculated from an engine exhaust system, and wherein the expected humidity is at or near maximum humidity.

5. The method of claim 2, wherein the second gas flow comprises crankcase gas from a crankcase vent tube, and wherein the expected humidity is at or near maximum humidity.

6. The method of claim 1, wherein the first gas flow comprises air from an air intake system, exhaust gas recirculation system, and crankcase ventilation system, wherein the second gas flow comprises crankcase gas and air from the air intake system, and wherein the expected humidity is at or near maximum humidity.

7. The method of claim 1, wherein the first gas flow comprises air from an air intake system at a first pressure, wherein the second gas flow comprises air from the air intake system at a second pressure, and wherein the expected humidity is a function of the humidity of the air from the air intake system at the first pressure and a difference between the first pressure and the second pressure.

8. The method of claim 1, wherein adjusting an engine operating parameter comprises adjusting an amount of exhaust gas recirculated from an engine exhaust to an engine intake.

9. A system comprising:

an engine coupled to an intake system and an exhaust system;

a humidity sensor; and

a controller including instructions to;

during a first condition when the humidity sensor is exposed to a first gas flow, adjust an engine operating parameter based output of the humidity sensor; and

during a second condition when the humidity sensor is exposed to a second gas flow, indicate degradation of the humidity sensor if output of the humidity sensor is different than an expected output.

10. The system of claim 9, wherein:

the humidity sensor is positioned in the engine intake system downstream of air intake system throttle,

the first condition comprises the air intake system throttle being in a fully open position,

the first gas flow comprises intake air at barometric pressure,

the second condition comprises the air intake system throttle being in a closed or partially closed position, and

the second gas flow comprises intake air at less than barometric pressure.

11. The system of claim 9, wherein:

the humidity sensor is positioned in an exhaust gas recirculation (EGR) passage outlet,

the first condition comprises an EGR valve being in a fully closed position,

the first gas flow comprises intake air,

the second condition comprises the EGR valve being in a partially or fully open position, and

the second gas flow comprises exhaust gas.

12. The system of claim 9, wherein:

the humidity sensor is positioned in a crankcase ventilation system vent tube,

the first condition comprises intake manifold pressure less than barometric pressure,

the first gas flow comprises intake air,

the second condition comprises intake manifold pressure greater than barometric pressure, and

the second gas flow comprises crankcase ventilation air.

13. The system of claim 9, wherein:

the humidity sensor is positioned in a crankcase ventilation system purge tube,

the first condition comprises a positive crankcase ventilation valve being in a fully closed position,

the first gas flow comprises intake air,

the second condition comprises positive crankcase ventilation valve being in fully or partially open position, and

the second gas flow comprises crankcase gases and crankcase ventilation air.

14. The system of claim 9, wherein:

the humidity sensor is positioned in a passage fluidically coupled to an engine intake manifold and to an intake passage upstream of an air intake system throttle,

the first condition comprises intake manifold pressure less than barometric pressure,

the first gas flow comprises intake air,

the second condition comprises intake manifold pressure greater than barometric pressure, and

the second gas flow comprises intake air, exhaust gas, and crankcase gas.

15. The system of claim 9, wherein:

the humidity sensor is positioned in a passage fluidically coupled to an intake passage upstream of an air intake system throttle and the intake passage downstream of a compressor outlet,

the first condition comprises intake manifold pressure less than barometric pressure,

the first gas flow comprises intake air,

the second condition comprises intake manifold pressure greater than barometric pressure, and

the second gas flow comprises intake air and exhaust gas.

16. The system of claim 9, wherein:

the humidity sensor is positioned in a passage fluidically coupled to an intake passage downstream of a compressor outlet and an exhaust passage downstream of a turbine outlet,

the first condition comprises intake manifold pressure greater than barometric pressure,

the first gas flow comprises intake air and exhaust gas,

the second condition comprises intake manifold pressure less than barometric pressure, and

the second gas flow comprises exhaust gas.

17. A method, comprising:

adjusting an engine operating parameter based on humidity of a gas flowing in a first direction; and

indicating degradation of a humidity sensor based on humidity of the gas flowing in a second, opposite direction.

18. The method of claim 17, wherein the gas flowing in the first direction includes the gas flowing from an intake passage upstream of an air intake system throttle to an intake manifold, and wherein the gas flowing in the second, opposite direction includes the gas flowing from the intake manifold to the intake passage upstream of the air intake system throttle.

19. The method of claim 17, wherein the gas flowing in the first direction includes the gas flowing from an intake passage downstream of a compressor outlet to an exhaust passage downstream of a turbine outlet, and wherein the gas flowing in the second, opposite direction includes the gas flowing from the exhaust passage downstream of the turbine outlet to the intake passage downstream of the compressor outlet.

20. The method of claim 17, wherein adjusting an engine operating parameter includes adjusting an amount of exhaust gas recirculated to an engine intake.