Method to detect loss of fluid or blockage in a hydraulic circuit using exponentially weighted moving average filter

摘要

Method for detecting a fault condition in a vehicular hydraulic circuit during a drive cycle using an electric pump includes monitoring an actual pump torque and monitoring a desired pump torque. A current confidence factor is determined based on the actual pump torque and the desired pump torque. An average confidence factor is iteratively calculated based on the current confidence factor and previously determined confidence factors. The average confidence factor is compared to a fault condition threshold. An absence of the fault condition in the hydraulic circuit is detected when the average confidence factor is at least the fault condition threshold, and a presence of the fault condition in the hydraulic circuit is detected when the average confidence factor is less than the fault condition threshold.

主权项

1. Method for detecting a fault condition in a vehicular hydraulic circuit during a drive cycle using an electric pump comprising:
within a control module:
monitoring an actual electric pump torque and a desired electric pump torque;controlling the electric pump to achieve the desired electric pump torque; and within a hydraulic circuit failure determination controller comprising a computerized processor imbedded in the control module, operating programming configured to:
iteratively determine a current confidence factor based on the actual electric pump torque and the desired electric pump torque;diagnose through the iteratively determined confidence factors the fault condition comprising one of a blocked hydraulic line and a low hydraulic fluid level, comprising:
applying a statistical filter comprising a weighted factor increasing statistical weight of recent confidence factor values, wherein the statistical filter is calibrated to:
filter out anomalous confidence factor values; andcalculate an average confidence factor;comparing the average confidence factor to a fault condition threshold;detecting a fault condition when the average confidence factor is less than the fault condition threshold; anddiagnosing the detected fault condition as one of the blocked hydraulic line fault condition and the low hydraulic fluid level fault condition based upon a comparison of the actual electric pump torque and the desired electric pump torque; andexecute a control action in response to the determined failure condition comprising at least one of,
recording a diagnostic trouble code corresponding to the determined failure condition, anddisplaying a message corresponding to the determined failure condition.