| 摘要 |
PURPOSE:To prevent the stress cracking of a gear by providing a tooth form having bottom parts indented with a radius of at least 0.5 R. CONSTITUTION:An internal gear 10 is constructed with bottoms between teeth, indented with a full radius of at least 0.5 R. The action of this gear 10 is to disperse the driving stress in the radius form of 0.5 R without having said driving stress concentrated in a specific position of a bottom part 14 even if said driving stress is applied to a tooth form 12 by allowing planetary gears to engage with the internal gear. Further, even if repetitive stress is applied to the bottom part 14 due to the engagement of the internal gear with the planetary gear, durable time until a stress crack occurs is greatly prolonged. Moreover, even if a pressure angle is taken large to obtain a bottom size to raise the rigidity of the tooth form 12, the durability of the internal gear can be greatly improved. |
