Humidity Sensor Diagnostics

• US 9,382,861 B2
• Filed: 02/22/2013
• Issued: 07/05/2016
• 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: Jankovic, Mrdjan J., Clark, Timothy Joseph, Makki, Imad Hassan, Pursifull, Ross Dykstra, Uhrich, Michael James
• Primary Examiner(s): Dager, Jonathan M
• Application Number:
  US13/774,234
• Publication Number:
  US 20140238369A1
• Time in Patent Office: 1,229 Days
• US Class Current: 1/1
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/144 Sensor in intake manifold
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Embodiments for testing a humidity sensor are provided. One example method comprises indicating degradation of a humidity sensor based on a humidity sensor output and output from an intake gas composition sensor. In this way, output from the intake gas composition sensor may be used to determine if the humidity sensor is degraded.

Claims

1. A method, comprising:

indicating degradation of a humidity sensor based on an output from the humidity sensor and an output from an intake gas composition sensor, wherein output from the intake gas composition sensor comprises an indication of intake air oxygen concentration.

2. The method of claim 1, wherein indicating degradation of the humidity sensor based on the output from the humidity sensor and the output from the intake gas composition sensor further comprises indicating degradation of the humidity sensor based on the output from the humidity sensor and the output from the intake gas composition sensor while exhaust gas recirculation (EGR) is off and responsive to output from the humidity sensor changing more than a threshold amount.

3. The method of claim 2, wherein indicating degradation of the humidity sensor based on the output from the humidity sensor and the output from the intake gas composition sensor further comprises, if the output from the humidity sensor decreases by more than the threshold amount, indicating degradation of the humidity sensor if the output from the intake gas composition sensor does not increase above a second threshold amount.

4. The method of claim 2, wherein indicating degradation of the humidity sensor based on the output from the humidity sensor and the output from the intake gas composition sensor further comprises, if the output from the humidity sensor increases by more than the threshold amount, indicating degradation of the humidity sensor if the output from the intake gas composition sensor does not decrease below a second threshold amount.

5. The method of claim 2, further comprising, if humidity sensor degradation is not indicated, adjusting an amount of EGR based on the output from the humidity sensor during a subsequent operation when EGR is on.

6. The method of claim 1, wherein the intake gas composition sensor is positioned downstream of the humidity sensor.

7. A system, comprising:

an exhaust gas recirculation (EGR) system;

a humidity sensor disposed in an engine intake system;

an intake gas composition sensor disposed in the engine intake system downstream of the humidity sensor; and

a controller including instructions to;

when EGR is disabled and if output from the humidity sensor changes by more than a threshold amount, indicate humidity sensor degradation based on the humidity sensor output and output from the intake gas composition sensor.

8. The system of claim 7, wherein the controller is configured to disable EGR during idle engine operation.

9. The system of claim 7, wherein the controller is configured to disable EGR in response to a humidity sensor test cycle.

10. The system of claim 7, wherein if the output from the humidity sensor increases by more than the threshold amount, the controller includes instructions to indicate humidity sensor degradation if output from the intake gas composition sensor is less than a second threshold amount.

11. The system of claim 7, wherein if the output from the humidity sensor decreases by more than the threshold amount, the controller includes instructions to indicate humidity sensor degradation if output from the intake gas composition sensor is greater than a second threshold amount.

12. The system of claim 7, wherein the intake gas composition sensor measures intake air oxygen concentration.

13. The system of claim 7, wherein the controller includes instructions to, when EGR is enabled, adjust an amount of EGR directed to the engine intake system based on the output of the humidity sensor.

14. The system of claim 7, wherein the humidity sensor is located in a first intake passage of the engine intake system, and further comprising a positive crankcase ventilation conduit coupling a crankcase of an engine to a second intake passage of the engine intake system.

15. A method comprising:

when exhaust gas recirculation (EGR) is enabled, adjusting an amount of EGR directed to an engine intake based on intake air humidity measured by a humidity sensor; and

when EGR is disabled, indicating humidity sensor degradation if measured intake air humidity does not correlate to measured intake air oxygen concentration.

16. The method of claim 15, wherein indicating humidity sensor degradation further comprises, if the measured intake air humidity increases and the measured intake air oxygen concentration does not decrease, indicating humidity sensor degradation.

17. The method of claim 15, wherein indicating humidity sensor degradation further comprises, if the measured intake air humidity decreases and the measured intake air oxygen concentration does not increase, indicating humidity sensor degradation.

18. The method of claim 15, wherein adjusting the amount of EGR based on intake air humidity includes decreasing the amount of EGR as intake air humidity increases.