MISFIRE DETECTION USING ION CURRENT INTEGRATION AND RPM ADAPTATION

摘要

An ignition system controlled by a powertrain controller via a dwell line carrying a dwell signal has a state machine to monitor a dwell period between consecutive dwell signals and to adjust a rate of a variable clock signal accordingly. A multi-bit counter is clocked by the adjusted clock signal. The counter has a first set of bits to establish an integration period and a second set of bits coupled to a resistive ladder generating a stair step signal. A current sensor provides a current signal proportional to the ion current. A comparator compares the current signal to the stair step signal. An ion current counter is incremented during the integration period whenever the current signal indicates an ion current magnitude greater than the stair step signal. The accumulated count at the end of the integration period is reported to the powertrain controller as a measure of the ion current.

主权项

1. An ignition system controlled by a powertrain controller via a dwell line carrying a dwell signal, comprising:
a state machine monitoring a dwell period between consecutive dwell signals and adjusting a rate of a variable clock signal according to the dwell period; a multi-bit counter clocked by the adjusted clock signal, the counter having a first set of bits used by the state machine to establish an integration period, and a second set of bits coupled to a resistive ladder generating a stair step signal having a plurality of cycles during the integration period; a current sensor providing a current signal proportional to the ion current; a comparator comparing the current signal to the stair step signal; an ion current counter incremented during the integration period whenever the current signal indicates an ion current magnitude greater than the stair step signal, wherein an accumulated count at the end of the integration period is reported to the powertrain controller as a measure of the ion current.