| Encased differential planetary train have been widely used in aerospace, wind power system, automotive, mine equipment and other fields due to their excellent drive characteristics. With the development of machinery products, power drive is increasingly required have to be high-quality, high precision and high reliability. In addition, the development of science and technology promote planetary transmission heading to the direction of’high, fine and sharp’, which has continually improved design and construction of planetary transmission as well as reliability. Because of manufacturing and assemble error of encased differential planetary gear box leads uneven load distribution during planet gears. How to more equally distribute load and improve the reliability is an important research subject that researcher.This thesis was written in seven chapters, and main research objectives and outcomes of each chapter are briefly described as following:In chapter one, an introduction of the background of this research was given, From the manufacture error, assemble error and load sharing method, the central member floating, flexible pin and flexible ring were described. A literature review of load sharing for the encased differential planetary transmission was delivered. The reliability of the encased differential planetary transmission was elaborated and the research contents and the significance of this thesis were outlined.In chapter two, Based on the characteristics of the encased differential planetary transmission, The Monte Carlo method was presented to build the load sharing model of the encased differential transmission which repeatedly stochastic sample in the range of manufacture and assemble error. The probability distribution of the load sharing coefficient and the sun floating for the encased differential system were investigate. Then an sensitivity analysis about the influence of tooth frequency error range, manufacture and assemble error range on the load sharing and the sun floating distribution for both encased and differential stages was put up.In chapter three, the dynamic load sharing model of an encased differential planetary gearbox, using the floating sun, flexible pin and flexible ring simultaneously, was build with the Monte Carlo method to stochastic repeatedly. The influence of tooth thichness error range and manufacture error range on the load sharing and the sun floating distribution for both encased and differential stages was researched, and then the unequal planet load was computed and counted.In chapter four, An encased differential planetary gearbox of MW wind turbine was tested to investigate the dynamic load sharing performance with multi load sharing measurements. A load sharing coefficient tackle method was proposed according to the tested tooth root bending strain, and then the varying of the dynamic load sharing characteristic for the gearbox was studied under different load condition. The mean load sharing coefficient and standard deviation for both the encased and differential stages were calculated and counted.In chapter five, an improved flexible load sharing structure for the ring is proposed based on that the tooth fails for too flexible ring and load sharing is bad for rigid ring, the stiffness models for parts and the system are built. The stress of the elastic pin and bolt were analysis according to the force status, and then structure optimization was made. The finite element model was used with orthogonal test to optimize the structure parameters and investigate their influence on system flexibility and part stess.In chapter six, based on the theory of interference for stress-strength distribution, this paper established reliability models of important parts in planetary transmission. Whole system reliability for the encased differential planetary transmission is formulated on the combination with system reliability theory and characteristic of hybrid system of planetary train. The system reliability considering unequal planet load was calculated.In chapter seven, the contents of this thesis were briefly summarized, and potential future work was also discussed.From the methods of theoretical analysis, experimental investigation as well as numerical simulation in this thesis, the load sharing characteristic of encased differential planetary transmission was researched, the result shows that the load sharing performance can be improved by control the manufacture and assemble error range of the planet. The flexible load sharing structure for the ring can help improve the flexibility of the ring and the load sharing characteristics to obtain the best system reliability. |
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