PROBLEM TO BE SOLVED: To limit rotation of a power transmission device without degrading transmission efficiency.SOLUTION: The power transmission mechanism includes a first carrier member 23 rotatable around the axis of a ring gear member 10, a second carrier member 33 rotating around the axis of the ring gear member 10, a first planetary gear member 20 meshed with the ring gear member 10, and a second planetary gear member 30 meshed with the first planetary gear member 20. The first planetary gear member 20 and second planetary gear member 30 are meshed at a position where faces including each axis and the axis of the ring gear member 10 intersect with each other, and a rotation regulation means 25 to regulate relative rotation in such a direction that the axes of the first planetary gear member 20 and the second planetary gear member 30 are separated, and to allow rotation in such a direction that the axes of the first planetary gear member 20 and the second planetary gear member 30 approximate is configured, thus relatively rotating the ring gear member 10 and the second carrier member 33.COPYRIGHT: (C)2011,JPO&INPIT【課題】伝達効率を低下させることなく動力伝達要素の回転を制限する。【解決手段】リングギヤ部材10の軸心を中心として回転可能な第1キャリヤ部材23と、リングギヤ部材10の軸心を中心として回転可能な第2キャリヤ部材33と、リングギヤ部材10に歯合する第1プラネタリギヤ部材20と、第1プラネタリギヤ部材20に歯合する第2プラネタリギヤ部材30とを備え、第1プラネタリギヤ部材20及び第2プラネタリギヤ部材30を、個々の軸心とリングギヤ部材10の軸心とを含む面が互いに交差する位置で歯合させ、第1プラネタリギヤ部材20及び第2プラネタリギヤ部材30の軸心が離隔する方向へ相対的に回転するのを規制する一方、第1プラネタリギヤ部材20及び第2プラネタリギヤ部材30の軸心が近接する方向へ回転するのを許容する回転規制手段25を構成し、リングギヤ部材10と第2キャリヤ部材33とを相対回転させている。【選択図】図1
