The mechanism of generation of noise was analyzed and research on noise reduction was conducted in pinion shift-type starters for idle stop systems. Both pinion shift noise and cranking noise are components of the noise generated during engine start; vehicle tests demonstrated that cranking noise is produced for a longer period and causes greater discomfort to driver and passengers, and countermeasures were therefore devised against this form of noise. Bench tests revealed that gear whine was a more significant factor in cranking noise than gear rattle, and countermeasures therefore targeted this source of noise. The spur gears conventionally used in pinion shifttype starters were replaced by helical gears and the contact ratio was increased, reducing noise by 7dB. When establishing gear specifications, analyses of stress in the sections making contact were conducted to enable judgment of the ease with which damage occurs to gear end faces during pinion gear shifting. The relation between angle and stroke of the pinion gears during shifting was optimized to achieve superior shift performance.
Article of Honda R&D Technical Review Vol.15 No.1 (151 - 158)