Method of setting optimum number of teeth of helical gear, and helical gear

TLDR: In this article, the authors proposed a method of setting the optimum number of teeth of a helical gear which can reduce gear noise more effectively by taking into consideration the hearing characteristics of a human.

Abstract: PROBLEM TO BE SOLVED: To provide a method of setting the optimum number of teeth of a helical gear which can reduce unpleasant gear noise more effectively by taking into consideration the hearing characteristics of a human. SOLUTION: A gear ratio, a distance between centers, a pressure angle, and a torsion angle between a pair of helical gears are determined, and the relationship between the number Z of teeth of each of the pair of helical gears and the engagement rate eof the pair of helical gears are calculated based on the values. Then the sound pressure level L G of the gear sound at the engagement frequency of the pair of helical gears is calculated from the relationship, and the sound pressure level of the gear sound is compared to a sound pressure level at the audibility limit with respect to the engagement frequency of the pair of helical gears of the vehicle, on which the pair of helical gears are mounted, at a predetermined vehicle speed. Then a frequency range is selected where the sound pressure level of the gear sound is relatively lower than that of the audibility limit, and the number of teeth which corresponds with the selected frequency range is set as the optimum number of teeth. COPYRIGHT: (C)2007,JPO&INPIT