A Knock Onset Predicting Model for Low Pressure Cooled EGR Boosted Gasoline Engines

作者：Chen, Longhua; Cheng, Qiang; Xu, Min; Gao, Yi

来源：Transactions of CSICE, 2017, 35(2): 142-148.

DOI：10.16236/j.cnki.nrjxb.201702021

• Effects of temperature
• Engine performance
• Gasoline engines
• Image processing
• methods
• Intake temperature
• Specific heat ratio
• Turbocharged gasoline engines
• Variable specific-heat

In considering the knock constrain when dealing with the one-dimensional engine performance simulation during the concept design stage, a predictive knock model was developed based on the integration of ignition delay of end mixture. The new model introduces the effects of temperature, pressure, EGR and air-fuel ratio. Knock experiments were conducted using a turbocharged gasoline engine, equipped with cooled EGR(exhaust gas recirculation) system. Knock characteristics are captured with signal filtering and image processing method. End gas temperature of each knock cycle is calculated with the isotropic compressing equation, considering the impact of parameters on specific heat ratio, and the impact of specific heat ratio solving method on end gas temperature. The new model was calibrated with multi-island generic algorithm. The predicting accuracy of the new model was compared with the classical model. Both increases in intake temperature and enrichment of charge decrease the specific heat ratio of the mixture, while cooled EGR increases the specific heat ratio. Large error occurs when solving the end gas temperature using constant specific heat ratio, instead of using variable specific heat ratio. The predicting error does not meet the requirements for the Hoepke model even if the model is recalibrated, while the new model can obtain a good performance and adaptability under different engines.

• 出版日期2017
• 单位上海交通大学