Experimental Study on the Relationship between Combustion and Vibration in a Gasoline Engine Part1 Study Overview and the Characteristics of Combustion’s Exciting Force

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 combustion characteristics for cycle-by-cycle and investigated indicators for the combustion’s exciting force. The engine vibration is affected by heat release characteristics even with the same engine structure specifications. The heat release characteristics were determined as indicators for the combustion’s exciting force. Transfer Path Analysis (TPA) revealed that there is piston transmission in the target frequency band. Through eigenvalue analysis, it was found that there was no resonance with the eigenvalue of the structures in the target frequency band. Even with the same combustion characteristics, the engine vibration is affected by piston specifications. Piston motion characteristics were determined as indicators for the structure’s exciting force. In this paper, after overview the impact of each exciting force on vibration, the heat release characteristics of the combustion’s exciting force and the indicators for vibration suppression are mainly discussed.