Internal combustion engine control with model-based barometric pressure estimator

摘要

An improved engine control utilizes a model-based technique to obtain an accurate estimate of barometric pressure with significantly reduced calibration time and effort. A mathematical model (Fig 3) of mass air flow through the engine intake system is used to estimate the pressure ratio across the intake system as a function of mass air flow, the effective intake area, and the intake air pressure and temperature. The barometric pressure is then determined from the estimated ratio, and used in the calculation of various gas flows for control purposes. The mass air flow information may be provided by a mass air flow sensor, or alternatively, may be determined based on engine flow rate estimations. Because the estimation is model-based, no special calibration is needed to ensure accuracy at high altitudes.