Transmission performance analysis of non-circular gear hydraulic motor

The non-circular planetary gear train is a critical component of the hydraulic motor. It consists of internal and external noncircular gears with variable centre distance and several planetary gears. Transmission performance of the planetary gear train is considerable important to the overall structure analysis. In this research, two kinds of design methods are used for 6-8 type non-circular gear hydraulic motor. The high-order ellipse and double circular arc non-circular planetary gear train pitch curves are designed respectively. The influence of different modelling methods on the transmission performance of the whole planetary gear train are discussed. The results show that in the transmission process of the non-circular gear motor planetary gear train, the abrupt change of the planetary gear speed and the abrupt change of the rotational angular velocity of the planetary gear are located at the largest and smallest direction of the inner ring gear. The volume of each closed chamber of the motor changes at different times, resulting in the overall displacement pulsation. Under the same conditions, double arc type non-circular gear hydraulic motor than higher-order ellipse non-circular gear hydraulic motor in the same chamber work cycle can be in and out of more volume of oil, with better transmission smoothness.