Transmission Error Prediction Method of Planetary Gears Taking Account of Alignment Error

The features of the support structures of the sun gear, carrier and ring gear that are the components of a planetary gear set result in large alignment error in the form of eccentricity or inclination. Such error causes the relative tooth flank error to vary periodically at each pinion position. The side band phenomenon modulated by the rotation of the rotating elements appears around the mesh order components of transmission error. With the conventional method of calculating transmission error, it is not possible to evaluate the side band phenomenon because of the inability to treat the periodical variation in the relative tooth flank error. Therefore, we have developed a new method of simulating the transmission error of planetary gear sets taking into account such periodical variation of the eccentricity and inclination direction of each element. The predicted values are then input into the calculation, making it possible to evaluate the side band phenomenon as well. Periodical variation in the relative tooth flank error due to alignment error returns to the original state when the relative rotation between the rotating elements has completed one revolution. Accordingly, by repeating the calculation until the relative rotation between the sun gear and the carrier or between the carrier and the ring gear has completed one revolution, the new method makes it possible to analyze transmission error taking into account the periodical characteristic of the shape of the tooth flank error due to alignment error. This new calculation method was applied to analyze the transmission error of an actual transmission, and the results showed that the side band phenomenon was also evaluated with relatively good accuracy.