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US 8,505,371 B2Granted
Methods for an exhaust fluid sensor
AssigneeFord Global Technologies, LLC
InventorsBret Alan Zimmerman, John Paul Bogema, Timothy L. Jenkins, Michiel J. Van Nieuwstadt
Life of this patent
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Abstract
Various methods are provided for diagnosing an exhaust fluid sensor disposed in an exhaust fluid passage. By monitoring the sensor during conditions when it is in contact with the exhaust fluid and when it is not in contact with the exhaust fluid, an expected change in the sensor output can be monitored to identify whether the sensor is generating sufficiently accurate readings.
Claims19
A method, comprising:
- indicating degradation of an exhaust fluid sensor positioned upstream of an exhaust injector based on a first reading when exhaust fluid is present at the sensor and a second reading after exhaust fluid is evacuated away from the sensor, wherein evacuating the exhaust fluid includes opening an injector after engine shutdown and reversing a pump direction to clear an exhaust fluid passage in which the sensor is positioned.
A method for diagnosing an exhaust fluid sensor, comprising:
- sensing a first exhaust fluid concentration in an exhaust fluid passage between a pump and an injector;
- responsive to a decrease in pump pressure, actuating a reverting valve to reverse pump flow, opening an injector for a threshold duration, and sensing a second exhaust fluid concentration in the exhaust fluid passage;
- and
- indicating degradation of the exhaust fluid sensor based on a difference between the first exhaust fluid concentration and the second exhaust fluid concentration.
1 more element
A method for diagnosing an exhaust fluid sensor, comprising:
- indicating degradation of the exhaust fluid sensor based on a first exhaust fluid concentration obtained when an exhaust fluid passage between a pump and injector is full relative to a second exhaust fluid concentration obtained when the exhaust fluid passage is empty;
- and
- decreasing a pump pressure, actuating a reverting valve to reverse pump flow, and opening an injector for a threshold duration to empty the exhaust fluid passage.
Dependencies are inferred from the claim text.