Analysis And Optimization Of Engine Noise

With the continuous improvement of user demand for the vehicle comfort, vehicle noise control level has become the focus of each manufacturer in the future competit ion. Foreign developed countries since the late 1960 s and early 1970 s in the form of regulations and standards to control the noise of the vehicle. Noise, Vibration and acoustic Vibration roughness (Noise, Vibration and Harshness, Harshness (NVH)) is a comprehensive measure of vehicle manufacturing quality problems, it gives the user th e feeling is the most direct and most surface. Statistics show, the vehicle around a thi rd of failure problem is related to the vehicle’s harshness (NVH) problems, and nearly 20% of the r&d companies use to deal with the problem of harshness (NVH) of the vehicle.At present, the execution engine noise limit standards:GB 14097-1999, the standa rd according to the regulations of the power and the calibration speed of medium and small power engine noise limit. We this project intends to adopt the engine is 4 a31p-T76, the power of 70 kw model calibration, calibration speed is 2300 RPM. Accor ding to the engine noise limit standard can find 4 a31p-T76 model of sound power level limit is 113 db (A), and through nine point method to test the aircraft noise sou nd power levels of 114 db (A), which explains the research of subject project is urge nt.In order to the noise control, and governance, it is necessary to analyze the acou stic characteristics of the noise, the noise spectrum. The amount of physical measurem ents and subjective evaluation of noise noise including sound pressure, sound intensity, sound power, sound pressure level and sound intensity level and sound power level a nd loudness and loudness level, etc.In this paper, through the use of noise source localization testing system of B&K, respectively from the engine front end, inlet side and the exhaust side scattering nois e test of engine is in three aspects:the focus position, through the analysis, it is cone luded that noise reducing vibration of the main parts in order for the gear train-gea r chamber cover optimization-sound-supercharger return pipe inlet-oil sump opti mize the fuel injection pump shell optimization and noise elimination---biaxial bal ance design optimization; Combining the reality of our work, we decided to priority t o optimize the gear chamber cover and the two oil pan thin-wall parts.By modal analysis to determine the natural frequency, engine parts inherent frequency and frequency response and determine the main optimization frequency, respectively through the topology optimization model for gear chamber cover and oil sump structure optimization, generate a new model, and test samples, test, to determine the correctness of the optimization direction, so as to achieve the purpose of the engine noise control.