Engine cylinder bank-to-bank torque imbalance correction

摘要

An engine bank-to-bank airflow balancing technique includes calculating current and offset volumetric efficiencies of the engine and calculating a slope representing (i) a difference between the offset and current volumetric efficiencies and (ii) a difference between offset and current intake camshaft positions. Based on the respective exhaust gas oxygen concentrations, the technique involves calculating a volumetric efficiency correction corresponding to each cylinder bank and based on the slope and the volumetric efficiency corrections, calculating target intake camshaft position shifts. The technique further involves controlling offsets of the intake camshafts based on the target intake camshaft position shifts. After a predetermined number of target intake camshaft position shifts are determined and stored with respect to various combinations of engine speed and a ratio of intake manifold pressure to barometric pressure, final intake camshaft position shifts may be determined and utilized when determining the intake camshaft positions.

主权项

1. A control system for an engine having two banks of cylinders associated with two intake camshafts, the system comprising:
intake camshaft position sensors each configured to measure a current position of a respective intake camshaft; exhaust gas oxygen concentration sensors each configured to measure an oxygen concentration of an exhaust gas produced by a respective cylinder bank; and a controller configured to detect a precondition for performing engine airflow balancing and, in response to detecting the precondition:
based on the current intake camshaft positions and offset intake camshaft positions, calculate current and offset volumetric efficiencies of the engine, the offset intake camshaft positions being a calibratable offset from the current intake camshaft positions;calculate a slope representing a ratio of (i) a difference between the offset and current volumetric efficiencies and (ii) a difference between the offset and current intake camshaft positions;based on the respective exhaust gas oxygen concentrations, calculate a volumetric efficiency correction corresponding to each cylinder bank;based on the slope and the volumetric efficiency corrections, calculate target intake camshaft position shifts; andbased on the target intake camshaft position shifts, control offsets of the intake camshafts.