| Under the project of XCMG Research Institute for specialist technique: Study on noise control for ZL50G wheel loader, taking ZL50G wheel loader as the research object, aiming at improving ability for the vibration and noise testing analysis of the wheel loader, aiming at meliorating the Noise status of the wheel loader, this dissertation is the research of pure theory and experiment.1: mainly elaborated the Problem and development condition for The Power-Train of the wheel loader, at the same time elaborated the purpose and content of this article.It is a widespread problem on the vibration and noise of the wheel loader. Noise control level of construction vehicle directly related to the product performance quality and market competition ability. Now the manufacturer of the wheel loader put a lot of attention on the research of vibration and Noise control. With the quick development of construction machine industry, People's request on comfort for construction vehicle is more and more strict. Nation standard《construction machine noise limit》(GB16710.1-1996) rule Present stage Lowest index sign for the domestic construction machine.The purpose of this article is meliorating vibration and noise status of The Wheel loader, by studying on the Main parts of ZL50G Wheel Loader and putting forward suggestion of vibration and Noise control and actualizing effective projects. Studying on the vibration and Noise control of the domestic construction machine has important meaning to develop the new generation environmental-protection product. Application of this technique could bring obvious economic performance and social performance.2: Analyzed creation mechanism and control path of the vibration and noise for the power-train of the wheel loader.The main factors of the wheel loader noise are the air motive, the machine transmission, the hydraulic pressure and the brake system. The noise comes from the power-train of the wheel loader and its parts have above 1/2 of all. Reduce vibration and decline noise for the power-train is the key to control of the wheel loader noise.Basis the mechanism of noise creation and spread, the technique for the noise control is divided into three sorts altogether: controlling to the origin of noise, controlling to the spread path of noise and protecting the acceptor. Noise and vibration control level of construction vehicle directly related to the product performance quality and manufacturing cost, the manufacturer must give attention to product hot equilibrium, dynamics, economy, dependability.3: The vibration and noise testing analysis of the wheel loaderTaking ZL50G wheel loader as the research object, this paper make noise and vibration experiment, obtain the noise and vibration spectrum. Through theory computation and analysis, the source of noise and transfer paths corresponding to every noise peak value are reconfirmed, the main aim to decreasing noise is pointed out. According as the nation standard (GB16710.1-1996), six points have been tested for the wheel loader noise. At the same time collected the vibration signal come from the engine, the transmission box, the radiator, the batholiths and the keep-air cylinder. Obtain the noise and vibration spectrum. Through analysis, Find out the source of noise.Taking noise as the break down symptom, through frequency spectrum, power spectrum and wavelet analysis, frequency spectrum is also analyzed and the main source and cause identified. By testing, build up a relation between the noise and vibration is testified. Taking as a kind of traditional analytical means, frequency spectrum analysis have important meaning in the actual engineering application for noise break down diagnosis.4: Basis the result of vibration and noise testing analysis, declined ZL50G Wheel Loader noise by actualizing effective reduce vibration and decline noise projects.(1) Reduce vibration projectsParts witch related to the low frequency Structure Borne Noise include the engine system and transmission system and carriage system. This is the main source of vibration. Key for this problem is optimizing the reduce-vibration mat of the power-train and the cab. So that, Main means of decline noise is using appropriation damping mounting for allied connect place.(2) Seal and sound absorption projectsAs far as possible Seal noise source, because the noise dissemination penetrates everywhere. See from the result of the test, noise data of the back obviously big in which of the frontal. The reason is that engine and fan been lay the back of the Wheel Loader. One of the important measures is sealing the main noise source by the engine cover and sound-absorption material.(3) Initiative decline noise projects: low-noise fan applicationCooling fan is one of the main noise sources for the wheel loader radiate noise. Fan noise could be declined by analyzing the structure parameter of old fan and changing the diameter of the fan, number of the leaf, material of leaf, at the same time, raising the static pressure and efficiency of fan.(4) Other measureOne of the important sources for the air-backset noise is the fan lead-breeze cover. Channels between the fan and the cover should be smooth, to improve the fluxion appearance of breeze. Decline the air-backset noise by re- designing the cover. at the same time, Decline machine noise because of resonance by changing structure and quality of the fan cover.One important component of the wheel loader radiate noise is the exhaust noise of engine that controlled mainly by re- matching a calculation and installing exhaust muffler. Design the high-efficiency exhaust muffler is the key for decline exhaust noise of engine.Cautiously analyzed the place of shortage of the reduce vibration and decline noise measure of ZL50G wheel loader. By knowing and using for reference Vibration and noise control technique of domestic and international Wheel loader. Through theory computation and testing analysis, Comprehensive usage noise and vibration of control method, actualizing effective projects. Through verification, the wheel loader noise condition had an obvious improvement. Radiate noise Lowered a 5 dB(A); Driver position noise Lowered a 5 dB(A), Come to an anticipant effect.
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