Apparatus for diagnosing individual cylinder performance by estimated instantaneous engine speeds

摘要

An engine equipped with a low resolution crankshaft rotation encoder is diagnosed by measuring the average speeds for each encoder period, deriving estimated instantaneous speeds for top dead center (TDC) positions for each cylinder and for the points midway between TDCs. Speed changes calculated from the estimated speeds for the compression and combustion phases of each cylinder provide measures of the compression and power output of each cylinder. An engine speed signature trace derived from the estimated speeds is displayed to reveal speed changes and a composite display of several consecutive signatures provides further information.