The Vibration Study Of Wheel Loader

With the development of the society, construction machineries have been widely applied. People pay more attention to driving comfort as well as product function. But the drastic vibration not only makes driver feel discomfort, but also has an influence on the product life. Thus reducing the vibration of construction machineries have become the research focus. The vibration of the wheel loader is researched in this paper mainly. The power system of wheel loader is the mainly vibration source. And the vibration damping of cab directly affect the driving comfort. The reasonable design of them could not only reduce the vibration, improve the driving comfort, but also enhance improve the service life of the machine. It is studied in this thesis for the problem of vibration damping of 5 ton wheel loader.The research status of mounting system at home and abroad was first described in the paper. The existing problem in construction machinery vibration and control method were introduced. According to the problems of wheel loader vibration, the mathematical models of power mounting system and cab mounting system was established. Through analyzing the mathematical model, the vibration transmissibility curve was obtained. The author analyzed the excitation frequency of the dynamic system and arrangement mode of the mounting system, discussed the relationship between rubber hardness and rubber stiffness, and summarized the basic requirements and criterion of the designing mounting system.The vibration measurement of dynamic system and cab system was carried out through LDS test system. And the isolation effect was analyzed and summarized. It was studied on the coincidence frequency among the whole machine vibration frequency, frame frequency and cab frequency by testing the natural frequency and vibration signal of wheel loader cab and rear frame. Through modal test of the rear frame, it’s found that the first-order and the second-order natural frequency of the frame were close to the excitation frequency of the engine, which would be easy to occur resonance. And the conclusion from the modal test also provided the direction for making further improvement.Finally, according to the damping theory and the improving-direction method from experiment, the dynamic assembly mounting system was redesigned, the shape and hardness of the mounting components were improved and the installation position of mounting system was changed in this paper. The add of U structure in the rear frame could reduce the mounting components hardness of the cab mounting system. It was verified through experiment again that the transmissibility of the improved dynamic system with the cab system decreased. And the natural frequency of the rear frame was far from the excitation frequency of the engine. Thus the isolation effect of wheel loader was improved.