| Cycloid planetary gear drive is applied extensively in micro-mechanical devices, robots, and test devices due to its advantages of high transmission precision, large transmission ratio, compact structure and a long service life. The study of cycloid drives mainly focuses on tooth profile modification, innovative structure and advanced manufacturing technology, while the lubrication performance of the cycloid drive has been mentioned not quite so much. The lubrication performance of cycloid drives in the meshing process affects the transmission precision, the contact fatigue, the transmission efficiency and the dynamic behavior of the system, so carring out analysis of lubrication characteristics of the cycloid drive will provide a good reference for tribological design.The main contents of this dissertation are shown as follows:① A time-varying thermal elastohydrodynamic lubrication line contact model is developed for the cycloid drive with newtonian fluid, Eyring fluid or Ostwald fluid. According to the meshing characteristics of cycloid drives, the equivalent radius, the rolling speed, the contact force, as well as other parameters within a whole meshing period can be achieved.② Research on lubrication characteristics of cycloid drives. The study of effect of different fluids on the friction coefficient and frictional power loss in the meshing process is conducted. The influence of the non-newtonian characteristics of Eyring fluid and Ostwald fluid and the working condition on lubriaction characteristics during the meshing process of the cycloid drive is discussed.③ The influence of design parameters on lubrication characteristics. The film thickness, friction coefficient and frictional power loss are selected to evaluate lubrication performance. The effect of the short width coefficient, the radius of pin gear and the modified parameters of tooth profile on lubrication characteristics is achieved.④ Study on starved lubrication performance of the cycloid drive. A numerical thermo-starved-elastohydrodynamic lubrication model is built, in which the parameter of the inlet oil film thickness is chosen to represent the starved degree. Effects of the inlet film thickness on the central film thickness, the starting position of the effective film thickness, the friction coefficient and the frictional power loss are investigated. The influence of working conditions and non-newtonian characteristics on the inlet film thickness is discussed.⑤ The effect of variation of oil-supply Layer on starved lubrication characteristics. The influence of variation of oil-supply Layer in the width direction on pressure and film thickness distribution is studied. Effect of different distribution of oil-supply Layer during the meshing process on lubrication characteristics is investigated. Finally, according to the different optimum objective, the optimum inlet oil-supply Layer during meshing process of a cycloid drive are calculated. |
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