Tooth Profile Calculation of a Cylindrical Gear Pair to Achieve a Non-constant Ratio

Mechanical vibration and acoustic noise of gear mechanism due to fabrication and elastic deformation is prevented by purposely given fluctuation of meshing contact cycle. The authors came up with the idea that the pinion and variable rack that achieve non-constant transmission ratio is applied to cylindrical gear pair, and have derived equations of a spur variable gear called “cylindrical variable ratio gear” and showed numerical example previously. In this paper, equations for helical gear pair is newly derived, and consider the constraint to achieve a continuum and periodic fluctuation of transmission. Next, the authors considered evaluation conditions of contact ratio and tip thickness, and show the numerical example that meets those conditions. After that, the numerical example is validated by experiment measuring angular displacement. The result showed that the gear pair fabricated for the experiment achieved a target angular displacement, and was demonstrated the feasibility of proposed calculation method.