Study of the influence mechanism of pitch deviation on cylindrical helical gear meshing stiffness and vibration noise

To analyze the influence mechanism of pitch deviation on cylindrical helical gear meshing stiffness and vibration noise, the calculation methods about meshing stiffness and engaging vibration of helical gear which consider actual pitch deviations are proposed. The numbering rules of gear meshing teeth in LTCA (Load Tooth Contact Analysis) were rearranged according to the contact ratio and tooth pitch deviation, and the time-varying meshing stiffness and the axial degree of freedom were considered in the helical gear vibration model. A numerical simulation of example based on helical gears with the given pitch deviation is performed, which proves that load transmission error and RMS (root mean square) value of meshing vibration acceleration with tooth pitch deviation are bigger than that with standard pitch. The percent deviation of meshing stiffness increased with the increase in contact ratio, but decreased gradually with increase in load. The resonant frequency of vibration acceleration with pitch deviation becomes smaller comparing to the frequency with standard pitch. This study provides evidence that it is essential to consider the influence of pitch deviation when we design the parameters and predict vibration of cylindrical helical gear transmission system.