Dual mode oxygen sensor
AssigneeFord Global Technologies, LLC
InventorsJames M. Kerns, Harry Burleson
Life of this patent
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Abstract
A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor is provided. The method may comprise pumping a current in a pumping cell during; reducing said pumping during a set of operating conditions; and adjusting a fuel injection amount or an air amount into the engine to maintain a desired air-fuel ratio based on the sensor. In this way, a reference voltage can be driven by chemical reactions to equilibrate and provide an accurate indication of stoichiometry, similar to a HEGO sensor. Likewise, outside of stoichiometry, the reference voltage is controlled in a one-sided fashion via positive and negative pumping current at respective voltage limits to provide an indication of air-fuel ratio over a wide range.
Claims18
A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor, the sensor having a pumping cell and a reference cell, the method comprising:
- pumping a current in the pumping cell during at least a first set of operating conditions;
- reducing said pumping during at least a second set of operating conditions;
- providing a signal from the sensor during at least the first and second sets of operating conditions;
- adjusting at least one of a fuel injection amount and an air amount into the engine to maintain a desired air-fuel ratio based on the signal during at least the first and second sets of operating conditions;
- and
- further comprising measuring a reference voltage, turning off the current to the pumping cell to allow the reference voltage to float within a voltage range, and applying the current to the pumping cell if the reference voltage is outside the voltage range.
A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor, the sensor having a pumping cell and a reference cell, the method comprising:
- pumping a current in the pumping cell to maintain a voltage across the reference cell at a limit of a first voltage region;
- reducing said pumping if the voltage across the reference cell is within the first voltage region;
- providing a signal indicative of an exhaust air-fuel ratio based on the current and the voltage across the reference cell;
- and
- adjusting a fuel injection amount into the engine based on the signal at least during feedback air-fuel ratio operation, at least when said pumping is reduced.
A method for sensing an air-fuel ratio of exhaust gasses from an engine of a vehicle using a sensor, the sensor having a pumping cell and a reference cell, the method comprising:
- pumping a current in the pumping cell during at least a first set of operating conditions;
- reducing said pumping during at least a second set of operating conditions;
- providing a signal from the sensor during at least the first and second sets of operating conditions;
- adjusting at least one of a fuel injection amount and an air intake amount into the engine to maintain a desired air-fuel ratio based on the signal during at least the first and second sets of operating conditions;
- determining degradation of the sensor based on an operating condition;
- and
- further comprising measuring a reference voltage, turning off the current to the pumping cell to allow the reference voltage to float within a voltage range, and applying the current to the pumping cell if the reference voltage is outside the voltage range.
Dependencies are inferred from the claim text.