Experimental Study on the Relationship between Combustion and Vibration in a Gasoline Engine Part 2 Characteristics of Structure’s Exciting Force and Overall Research Summary

Following Part 1 of the previous study, this paper reports the structure’s exciting force and summarize the overall research results. An experimental study was conducted to clarify the relationship between engine combustion and vibration, and to establish technology to suppress it. This study focused on the vehicle interior noise caused by combustion in which vibration transmission is the main component at high speed and high load region. A phenomenon in which both the combustion’s exciting force and the structure’s exciting force are combined is defined as vehicle interior noise caused by combustion. Conventionally, combustion and vibration are often discussed in terms of the average cycle, but considering the nonstationary property of vibration, in this paper analyzed the structure’s exciting force characteristics for vibration in cycle-by-cycle. Analysis was conducted using the combustion indicators clarified in the previous study. The engine vibration is affected by piston specifications even with the same heat release characteristics. Based on the analysis results, the piston rotation angle and translational displacement are defined as indicators of the structure’s exciting force. In this paper, after discussing the piston motion characteristics as the structure’s exciting force and the indicators of vibration suppression, the results clarified by the research combined with the previous study are summarized.