Humidity sensor diagnostic method using condensation clearing heater

Patent metadata

Field	Value
Publication number	US-2016245240-A1
Application number	US-201615143254-A
Country	US
Kind code	A1
Filing date	Apr 29, 2016
Priority date	Apr 5, 2013
Publication date	Aug 25, 2016
Grant date	—

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.

First claim

1 . A method, comprising
operating a sensor in an engine intake of an engine having a turbocharger including a compressor and a turbine, a passage of the sensor including a temperature-sensing element, a heater, and a capacitance-sensing element; individually distinguishing between each of heater, temperature-sensing element, and capacitance-sensing element degradation; and setting a diagnostic code indicating the distinguished degradation.

2 . The method of claim 1 , wherein sensor provides an indication of humidity.

3 . The method of claim 2 , wherein the humidity is based on the capacitance-sensing element output.

4 . The method of claim 3 , wherein the indication of humidity is one or more of relative humidity, specific humidity, or absolute humidity.

5 . 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.

6 . The method of claim 5 , 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.

7 . The method of claim 1 , wherein the distinguishing is based at least on different absolute humidity readings determined at different temperatures.

8 . The method of claim 1 , wherein the distinguishing is based at least on specific humidity.

9 . A system, comprising:
an engine having a compressor in an engine intake system; a sensor coupled in the engine intake system having a condensation heater, a capacitance sensor, and a temperature sensor; a control system with sensors and actuators, including the sensor coupled in the engine intake, and actuators responsive to humidity including an exhaust gas recirculation actuator adjusted responsive to the humidity, to indicate capacitance-based humidity sensor degradation in response to a measured humidity of the sensor; and indicate degradation within a component of the humidity sensor in response to temperature sensor degradation.

10 . The system of claim 9 , wherein the sensor is coupled in an exhaust gas recirculation (EGR) passage.

11 . The system of claim 10 , wherein the control system increases an amount of EGR gas recirculated into the engine intake if the measured humidity increases.

12 . The system of claim 11 , wherein the control system further adjusts engine torque.

13 . The system of claim 9 , wherein the measured humidity is one or more of relative humidity, specific humidity, or absolute humidity.

14 . The system of claim 9 , wherein humidity sensor degradation is indicated if an error between a modeled humidity and the measured humidity exceeds a threshold.

15 . The system of claim 9 , wherein the control system determines a relative humidity based on the measured humidity and indicates humidity sensor degradation if the relative humidity falls above a predetermined relative humidity maximum or below a predetermined relative humidity minimum.

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

17 . The system of claim 9 , wherein during a first condition allowing the engine to equilibrate following a vehicle-off event, the control system measures a temperature within the humidity sensor using the temperature sensor, and measures the temperature in one or more locations within the engine system using additional temperature sensors; and indicates temperature sensor degradation if the temperature sensor measurement does not fall between a range of values determined by the additional temperature sensors.

18 . The system of claim 9 , wherein the control system indicates capacitance sensor degradation if humidity sensor degradation is indicated and temperature sensor degradation is not indicated.

19 . The system of claim 9 , wherein the control system indicates temperature sensor degradation if humidity sensor degradation is indicated and temperature sensor degradation is indicated.

Assignees

• Ford Global Tech Llc

Inventors

• Pursifull Ross Dykstra
• Makki Imad Hassan
• Clark Timothy Joseph
• Uhrich Michael James
• Kumar Pankaj
• Kim Yong-Wha

Classifications

• F02M26/04

  with a single turbocharger · CPC title

• G01N27/223

  for determining moisture content, e.g. humidity (rain detectors on vehicle windows B60S1/0825) · CPC title

• G01N33/007

  Arrangements to check the analyser (calibrating gas analysers G01N33/0006) · CPC title

• F02M26/52

  Systems for actuating EGR valves · CPC title

• F02M26/49 Primary

  Detecting, diagnosing or indicating an abnormal function of the EGR system · CPC title