Study On Design Technology And Load Sharing For High Reliability Planetary Gear Transmission

The planetary gear transmission equipment is the key device of the large-scale energy equipment, such as nuclear power and wind power etc.. It is also an important part of technology research and development for the large-scale energy equipment in China. The reliability of its operation is directly related to the whole unit's performance. At present, the gear transmission equipments used in nuclear power, wind power and other large-scale energy equipments in China rely largely on import, especially nuclear power gearboxes need to import totally. Our gear design and manufacturing technology is still difficult to meet the needs of the large energy equipment, especially in nuclear power and wind power equipments. Therefore, The researches on the planetary gear transmission equipment will take a great advantage for improving gear industry's technical level, speeding up the development of the large-scale energy equipments in China, and realizing localization of the transmission device as soon as possible in the large-scale energy equipment, such as nuclear power, wind power etc..In this dissertation, the vertical planetary gearbox for the million-kilowatts-class nuclear power circulating pump is taken as the research object. The parameters design, reliability and load sharing in dual-floating planetary transmission system are studied. The analysis theory and methods of the gear system with high reliability are improved. The major research works and conclusions in the paper are as follows:1. According to the importance of the high reliability, high power density in the planetary gear transmission for large-scale energy equipments, such as the nuclear power, wind power energy equipments etc., the fuzzy and random parameters are introduced in the design model. And taking the maximum power density and the smallest outer diameter of ring gear as the design objectives, the mathematical model of multi-objective fuzzy reliability optimization design is established. Examples show that the method can flexibly get design scheme according to the reliability that the designers give, the design purpose of high reliability and high power density is achieved. At the same time, the method is also applicable to the design of other mechanical products, and has a wide range of practicality.2. The effect of center distance, modulus, limit stresses and other factors to fuzzy reliability of the gear bending strength and pitting resistance in the planetary gear transmission is studied. The curves of the relationship between fuzzy reliability and safety factor of the gear bending strength and pitting resistance are founded. These are of great guiding significance for high-reliability design of gear transmission.3. For the thin-shell crown gear coupling that has important influence on the load sharing performance, finite element analysis and theoretical analysis are carried out; and the effects of the geometric parameters on deformation and stress are analyzed. At the same time, the comparative study of theoretical analysis and finite element analysis is done, some instructive conclusions are obtained. Finally, the stiffness of thin-shell crown gear coupling is analyzed and calculated.4. The statics physical and mathematical models of the dual-floating planetary transmission system are established. The calculation method of the load sharing coefficient on dual-floating planetary transmission system is studied. The effects of floating structures type, stiffness, the number of planetary gear and speed on the load sharing performance of system are discussed.5. The nonlinear dynamics model of dual-floating planetary transmission system is established. The non-linear differential equations of multi-clearance, variable parameters and the multi-degree of freedom are deduced. To deal with the problem that the original differential equations are not easy to analyze and solve, the appropriate coordinate transformation is selected, and a unified equation of analysis model of non-linear and dimensionless is established.6. According to the nonlinear dynamics model and equations of dual-floating planetary transmission system, The calculation method of the load sharing coefficient under the conditions of dynamics is derived. Numerical integration method is used to calculate the time history of the nonlinear dynamics model in dual-floating planetary transmission system. The effects of planetary gear eccentric error, time-varying mesh stiffness, gear backlash, speed, the number of planetary gear and floating structures type on the load sharing performance of system are analyzed. The relationship between the main influence factors and floating displacement of center gears are studied.