Humidity sensor diagnostic method using condensation clearing heater

• US 9,329,160 B2
• Filed: 04/05/2013
• Issued: 05/03/2016
• Est. Priority Date: 04/05/2013
• 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, Kim, Yong-Wha
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): Siwoku, Yusuf O
• Application Number:
  US13/857,884
• Publication Number:
  US 20140298880A1
• Time in Patent Office: 1,124 Days
• Field of Search: 73/10.6, 73/10.2, 734/321, 738/659, 733/350.1, 374/141, 374/142, 374/144, 361/286, 701 291- 312
• US Class Current: 1/1
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 41/04 Introducing corrections for particular operating conditions F02D41/14 takes precedence
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: F02M 26/04 with a single turbocharger
• CPC Class Codes: F02M 26/47 the characteristics being temperatures, pressures or flow rates
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: F02M 26/52 Systems for actuating EGR valves
• CPC Class Codes: F02M 35/10393 for characterising a multi-component mixture, e.g. for the composition such as humidity, density or viscosity
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers
• CPC Class Codes: G01N 33/0008 Details concerning storage of calibration data, e.g. in EEPROM
• CPC Class Codes: G01N 33/007 Arrangements to check the analyser calibrating G01N33/0006
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A diagnostic method for a capacitive humidity sensor comprising a heater, and a capacitance-sensing element that individually identifies heater, temperature-sensing element, or capacitance-sensing element degradation. By this method, individual elements of the sensor may be replaced or compensated for to allow for further operation.

Claims

1. A method, comprising

operating a sensor in an engine intake, a passage of the sensor including a temperature-sensing element, a heater, and a capacitance-sensing element;

and

individually distinguishing between each of heater, temperature-sensing element, and capacitance-sensing element degradation.

2. The method of claim 1 wherein an order of diagnostics among the heater, temperature-sensing element, and capacitance-sensing element degradation includes first determining whether overall degradation is present, and second determining temperature-sensing element degradation.

3. The method of claim 2 wherein the distinguishing is based on the first and second determination, and further includes indicating capacitance-sensing element degradation if overall degradation is present and temperature-sensing element degradation is not present, indicating temperature-sensing element degradation if overall degradation is not present and temperature-sensing element degradation is present, and indicating heater degradation if overall degradation is present and temperature-sensing element degradation is present.

4. The method of claim 3 wherein the overall sensor degradation is based on whether relative humidity is within a range.

5. The method of claim 3 wherein the overall sensor degradation is based on different absolute humidity determined at different temperatures.

6. The method of claim 3 wherein the overall sensor degradation is based on specific humidity.

7. A method for an engine system, comprising;

indicating capacitance-based humidity sensor degradation, the sensor including a temperature sensor, in response to a measured humidity of the sensor; and

indicating degradation within a component of the humidity sensor in response to temperature sensor degradation.

8. The method of claim 7, wherein the measured humidity is one or more of relative humidity, specific humidity, or absolute humidity.

9. The method of claim 8, further comprising indicating humidity sensor degradation if an error between a modeled humidity and the measured humidity exceeds a threshold.

10. The method of claim 8, further comprising determining a relative humidity based on a measured humidity and indicating humidity sensor degradation if the relative humidity falls above a predetermined relative humidity maximum or below a predetermined relative humidity minimum.

11. The method of claim 10, wherein the predetermined relative humidity maximum is between 90% and 100% and the predetermined relative humidity minimum is between 15% and 30%.

12. The method of claim 8, further comprising:

at a first condition, measuring a temperature within the humidity sensor and measuring an absolute humidity;

at a second condition, measuring the temperature within the humidity sensor and measuring the absolute humidity; and

indicating humidity sensor degradation if a change in absolute humidity is not within a predetermined error range determined by a change in temperature.

13. The method of claim 8, further comprising:

at a first condition, measuring a temperature, measuring an absolute humidity, and calculating a relative humidity or specific humidity;

at a second condition, measuring the temperature, measuring the absolute humidity, and determining the relative humidity or specific humidity; and

indicating humidity sensor degradation if a change in specific humidity is greater than a threshold.

14. The method of claim 13, wherein determining the threshold includes determining a vapor pressure, ambient pressure, partial pressure, or saturated pressure within the humidity sensor.

15. The method of claim 8, further comprising, during a first condition allowing the engine to equilibrate following a vehicle-off event, measuring a temperature within the humidity sensor using the temperature sensor, and measuring the temperature in one or more locations within the engine system using additional temperature sensors;

and indicating temperature sensor degradation if the temperature sensor measurement does not fall between a range of values determined by the additional temperature sensors.

16. The method of claim 8, further comprising indicating temperature sensor degradation if the temperature sensor measures a temperature above 150 degrees Fahrenheit during a vehicle cruising condition.

17. The method of claim 8, further comprising indicating capacitance sensor degradation if humidity sensor degradation is indicated and temperature sensor degradation is not indicated.

18. The method of claim 8, further comprising indicating temperature sensor degradation if humidity sensor degradation is indicated and temperature sensor degradation is indicated.

19. A method, comprising

operating a sensor in an engine intake of an engine coupled in a road vehicle, a passage of the sensor including a temperature-sensing element, a heater, and a capacitance-sensing element;

and

individually distinguishing between each of heater, temperature-sensing element, and capacitance-sensing element degradation; and

indicating identified degradation by setting a diagnostic code.

20. The method of claim 19 wherein an order of diagnostics among the heater, temperature-sensing element, and capacitance-sensing element degradation includes first determining whether overall degradation is present, and second determining temperature-sensing element degradation, wherein the distinguishing is based on the first and second determination, and further includes indicating capacitance-sensing element degradation if overall degradation is present and temperature-sensing element degradation is not present, indicating temperature-sensing element degradation if overall degradation is not present and temperature-sensing element degradation is present, and indicating heater degradation if overall degradation is present and temperature-sensing element degradation is present.