| Small gasoline engine is a kind of widely used power equipment. Vibration andnoise produced by the body is very outstanding as it usually has only one cylinder. Soreducing vibration and noise is particularly important. Combining the actual conditionsof enterprise product development, generating mechanism of vibration and noise andpropagation characteristics was researched systematically in this dissertation.(1) The mechanism of engine body vibration noise was analyzed.The frequency spectrum characteristic of vibration and noise sources was analyzedby the simulation models of crank-connecting rod mechanism, valve timing mechanism,cylinder side knocking, which were established using AVL software. The frequencyrange of all kinds of vibration and noise sources was determined.(2) Mode analysis was used in the body’s main partsFrom two aspects of experiment and simulation, the body vibration mode wasanalyzed to identify the weak part of body structure. Then, the weak parts wereoptimized according to referring to frequency range of the vibration and noise.(3) The effect of reducing vibration and noise was predicted through the simulationmethod in optimized major parts.Research results show that: the frequency of noise sources is different in the body’sdifferent parts, but they are basically in the range of0~3000Hz; there are multiplemodes in the frequency rang of vibration and noise sources in the body side covers, soresonance phenomenon is easily occurred when engine normal works. They are themain vibration and noise radiation surfaces, requiring to be optimized. At last, Theprediction results reveal that the structure optimization is reasonable, and noise radiationintensity of the side covers surface is decreased obviously. |
