Abstract
In recent years, fuel economy regulations for automobiles have been strengthened. Engine stop technology (idling stop / electric power run) is an effective method for improving vehicle fuel economy. Engine stop technology reduces the fuel consumption of the internal combustion engine, but restarting the internal combustion engine causes body vibration. This body behaviour contributes to a feeling of discomfort for passengers. Therefore, the formulation of a prediction technology that includes both the powertrain and the body is required in order to clarify a method of suppressing body vibration. In this study, authors focused on body vibration at engine restart generated by the transfer of engine vibration to the body. The authors used an engine control simulator, a combustion simulator, an engine vibration generation simulator and a body vibration simulator. These simulation tools were chosen through an investigation of prediction methods for in-cylinder pressure fluctuation in chamber, transmission and motor vibrations. The engine controller was made by MATLAB/Simulink. GT-SUITE was used as the chamber simulator. Thus, combustion simulator was original model included several mount model. In addition, CarMaker was used as the body vibration simulator. Finally, the authors created a prediction technology that worked cooperatively in the above-mentioned simulators. The prediction technology produced the correct results for an experiment inspection result (in-cylinder pressure, engine block acceleration, engine mount acceleration and seat vibration). Therefore, this prediction technology realized the prediction of body vibration during engine stop/restart, and enabled the optimal design for engine control, combustion and mounts. In this study, we focused on a vibration of relatively low frequency. The prediction of highfrequency body vibrations may require more detailed modelling. In addition, vehicle specifications are not decided just by vibration requirements. Therefore, this prediction technology should be extended to a prediction method for trade-off performance (i.e. fuel consumption, emissions, vehicle dynamics and thermal management). The formulation of a prediction technology including both the powertrain and the body is a new approach as a prediction method for body vibration. In addition, this prediction technology has the possibility to extend to application as a predictor of vehicle performance. The formulation of a prediction technology that included both the powertrain and the body was performed. This technology combined an engine control model, a combustion model and a mount model to suppress body vibration.