Patent ID: 7810238

Claim:
A manufacturing method for a helical gear pair, comprising: determining a gear ratio of the helical gear pair, an inter-center distance between centers of the helical gear pair, a pressure angle of the helical gear pair, and a helix angle of the helical gear pair; calculating a relationship between a contact ratio of the helical gear pair and a number of teeth of each helical gear of the helical gear pair on the basis of the determined gear ratio, inter-center distance, pressure angle, and helix angle; calculating a sound pressure level of a gear sound of the helical gear pair at a meshing frequency of the helical gear pair from the relationship between the number of teeth of each helical gear of the helical gear pair and the contact ratio; comparing the calculated sound pressure level of the gear sound with the sound pressure level of an audible limit with respect to the meshing frequency of the helical gear pair at a predetermined vehicle speed of an automotive vehicle in which the helical gear pair is mounted to select a frequency region in which the calculated sound pressure of the gear sound is low compared to the sound pressure level of the audible limit; and setting the number of teeth of each helical gear of the helical gear pair corresponding to the selected frequency region to an optimum number of teeth of each helical gear of the helical gear pair; and manufacturing the helical gear pair on the basis of the set optimum number of teeth of each helical gear of the helical gear pair.