Real time model predictive idle speed control of ultra-lean burn engines: experimental results

Idle speed control of ultra-lean burn engines continues to be a major focus of automotive engineers owing to the benefits offered in terms of fuel economy and emissions reduction. This paper applies a recently proposed linear time varying model predictive approach for the idle speed control of ultra-lean burn internal combustion engines. Unlike conventional gasoline engines, the approach uses fuel flow as the primary control variable to compensate for sudden fluctuations in engine load resulting in a fuel assisted idle speed control strategy. Simultaneously, the spark angle is maintained at a value so as to yield maximum brake torque while the emissions are reduced to negligibly low levels by constraining the engine operation to ultra-lean burn mode. The technique is demonstrated on an inline prototype 4-litre, 6-cylinder hydrogen fuelled internal combustion engine.