Intake Charge Measurement And Control Strategies Of A Gasoline Engine Equipped With Variable Valve System

Variable valve technology is one of the most applicable measures to improving fuel economy, power performance and emissions of conventional SI engines. But this technology also has poised a higher demand for measurement and control strategies of engine mass air flow. This paper investigated on the accurate measurement of the intake mass and the control strategy for a Gasoline Engine which equipped with fully variable valve systems and this engine has been taken out the throttle body.Both of the simulation and experiment method is introduced in this research, the eigenvalue of the waveform from the hot film flowmeter which is effected by the pulsant airflow has been analyzed. The response characteristic and how the airflow is effected by the parameters of the valves the response characteristic is also studied on the full operation range.The results show that, compared to the traditional SI combustion mode, the intake air waveform is much more fluctuant on the combustion mode, and the traditional collection method cannot satisfy the requirement. A measuring window is found in every cycle in the intake airflow waveform on the combustion mode which depends on the parameters of the valves. The average value of the intake airflow waveform in this window has liner relationship with the intake air mass flow. The position of the window is effected by the structure and the operation mode of the engine, so the calibration is needed.Both the simulation and the experiment method is used to study the SI combustion which is controlled by the variable valve. The multidimensional fitting is introduced to modeling the simulation data which is validated by the experiment data. After the fitting, we found a formula which can be used on the feedforward control.We found that when the engine speed is increased slowly, the fuel economy is also good when the airflow is controlled by the valves. When the engine speed is increased fleetly, the dynamics is the most important. We also found a fastest route to adjust the parameters of the valves by compare the adjust response of the intake airflow on different combination of the parameters of the valves, which can fulfill the requirement of the usual drive.