Physically a four cycle spark ignition engine operates on the basis of four engine processes or events: intake, compression, ignition (or expansion) and exhaust. These events each occupy approximately 180° of crank angle. In conventional engine controllers, it is an accepted practice to sample the engine variables synchronously with these events (or submultiples of them). Such engine controllers are often called event-based systems. Unfortunately the main system noise (or disturbance) is also synchronous with the engine events: the engine pumping fluctuations. Since many electronic engine controllers are event sampled systems, the sampling frequency is thus also frequency locked to the main system disturbances. This creates a signal analysis problem which has, to the authors' knowledge, not been treated in detail in the literature. This paper concerns itself with the impact of this and related problems on accurate air/fuel ratio control of a spark ignition (SI) engine.
|Title of host publication||Proceedings of the American Control Conference|
|Publication status||Published - 1994|
|Event||1994 American Control Conference - Baltimore, MD, United States|
Duration: 29 Jun 1994 → 1 Jul 1994
|Conference||1994 American Control Conference|
|Period||29/06/1994 → 01/07/1994|