| 摘要 |
A fault detection and response system having particular applicability for use with oxygen sensors and closed loop control systems. The system includes a confidence measuring unit as part of a fault control unit (26) that maintains a measure of confidence with respect to the recent operating history of the oxygen sensor. This measure of confidence is increased upon detecting state changes of the oxygen sense signal through use of a state change detector (24), and decreased upon detecting that an integrated form of the oxygen sense signal has attained a predetermined limit as sensed by a limit detector (22). Based upon this measure of confidence, the system can respond to perceived fault conditions in various ways. In general, with a high measure of confidence being present, the system will favor closed loop control even in the presence of a perceived oxygen sensor fault. Similarly, with a low measure of confidence, the system will favor open loop control. During such open loop control, however, occasional attempts at closed loop control will still be made, as the system ultimately favors closed loop control over open loop control.
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