Oxygen sensor monitoring arrangement
First Claim
1. A method for detecting proper functioning of an oxygen sensor mounted in an engine exhaust stream of a vehicle and in communication with an engine controller, the method comprising the steps of:
- initiating the method at the engine controller only when at least one engine operating condition satisfies a predetermined criterion whereunder the method will not intrude upon the engine controller'"'"'s ability to minimize undesirable exhaust emissions;
determining at least one mathematical characteristic from a sequence of readings of an output of the sensor over a predetermined time interval;
comparing the at least one characteristic to a corresponding standard; and
determining proper functioning of the sensor whenever the at least one characteristic compares favorably to its corresponding standard.
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Accused Products
Abstract
A non-intrusive method and arrangement for detecting the aging of an oxygen sensor, without increasing tailpipe emissions, is provided. The method detects an aging oxygen sensor, located between a motor vehicle engine and a catalytic converter, by sampling a series of oxygen level signals taken over a calibratable time block only when at least one engine operating condition. satisfies a predetermined criterion whereunder the method will not intrude upon the engine controller'"'"'s ability to minimize undesirable exhaust emissions. After a series of signal processing, the samplings are then compared to calibratable thresholds in order to determine the aging degree of the oxygen sensor.
9 Citations
19 Claims
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1. A method for detecting proper functioning of an oxygen sensor mounted in an engine exhaust stream of a vehicle and in communication with an engine controller, the method comprising the steps of:
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initiating the method at the engine controller only when at least one engine operating condition satisfies a predetermined criterion whereunder the method will not intrude upon the engine controller'"'"'s ability to minimize undesirable exhaust emissions;
determining at least one mathematical characteristic from a sequence of readings of an output of the sensor over a predetermined time interval;
comparing the at least one characteristic to a corresponding standard; and
determining proper functioning of the sensor whenever the at least one characteristic compares favorably to its corresponding standard. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for detecting proper functioning of an oxygen sensor mounted in an engine exhaust stream of a vehicle and in communication with an engine controller, the method comprising the steps of:
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initiating the method at the engine controller only when engine operating conditions satisfy a predetermined set of criteria whereunder the method will not intrude upon the engine controller'"'"'s ability to minimize undesirable exhaust emissions;
determining a plurality of mathematical characteristics from a sequence of readings of an output of the sensor over a predetermined diagnostic time interval;
comparing at least one of the characteristics to a corresponding test standard; and
determining the sensor is functioning properly whenever the at least one characteristic compares favorably to its corresponding standard. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A non-intrusive method for detecting aging of an oxygen sensor mounted in an engine exhaust stream of a vehicle and in communication with an engine controller, the method comprising the steps of:
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initiating the method at the engine controller only when engine operating conditions satisfy a predetermined set of criteria whereunder the method will not intrude upon the engine controller'"'"'s ability to minimize undesirable exhaust emissions;
obtaining from the oxygen sensor a series of consecutive sensor output signals taken over a plurality of time blocks;
summing the series of output signals for each block;
determining a maximum and a minimum value of the series of output signals for each block;
determining an absolute value of the difference between each pair of consecutive output signals (delta signals) in the series for each block;
obtaining an average flow rate within each block;
storing, for each block, the sum of the series of output signals, a sum of the delta signals, the maximum output signal and the minimum output signal;
compensating the sum of the delta signals for each block in accordance with the average exhaust flow rate of the block;
determining, from all blocks, an average value of the sensor output signals, an average value of compensated delta signals, an average maximum value and an average minimum value;
comparing each average value determined in the preceding step to an associated test standard; and
determining acceptable aging of the sensor whenever each average value compares favorably with its associated test standard. - View Dependent Claims (17, 18)
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19. An arrangement for detecting the aging of an oxygen sensor mounted in an engine exhaust stream of a motor vehicle, the arrangement comprising:
an engine control module coupled for receipt of output signals from the oxygen sensor and operable to determine at least one mathematical characteristic from a sequence of readings of sensor output signals over a predetermined time interval only if at least one engine operating condition satisfies a predetermined criterion, the engine control module further operative to compare the at least one characteristic to a corresponding standard and to determine acceptable sensor aging whenever the at least one characteristic compares favorably to its corresponding standard.
Specification