Control And Analysis On Noise Vibration Of Single-cylinder Gasoline Engine

Due to the more stringent legislations of vehicle noise and emission as well as the increasing expectation by the consumers, researches on the noise, vibration and harshness (NVH) have become more important in recent years. With the development of industry and transportation, engine's noise and vibration have become more critical. Noise index is an important aspect in evaluating engine's performance. It's important to Analysis and control the engine noise today.By integrating of experiment and theory analysis, the vibration and noise of single-cylinder gasoline engine of JL125 are tested by applying the vibration noise test device of B&K. The noise source is identified by using measuring sound intensity technique. It indicates that induction noise and exhaust noise are the main source, the cylinder body is second. The separate test of noise is done with method of individual operating. It obtains that the burner noise is the main part when engine is at low speed; whereas the piston slaps noise is dominant when the engine is at the high speed. The experiment of noise and vibration for gasoline body noise is done, and the sound energy of each noise source is obtained. The analysis of frequency characteristic and vibration signal of the noise for piston slaps noise, valve train noise and primary gear noise is researched. It indicates that It obtains that the slaps noise of valve clearance is the main source of admission gear when engine is at low speed; whereas the knock noise which the valve drops bed is dominant part when the engine is at the high speed. The frequency signals of valve acceleration and cylinder body acceleration are regular. The energy are focus on the several given frequency in the range of low frequency. The noise caused by primary gear mechanism increases as the torque enlarges. It can be seen from the acceleration spectrum that the vibration and noise can be reduced when the gear is widened, the modification coefficient for gear is modified and the machining precision is improved. The control mechanism of machine noise is studied. The surface emissive noise of the gasoline engine body is analyzed lastly.