PROBLEM TO BE SOLVED: To provide a power transmission unit, in which deterioration of a power transmission shaft is suppressed.SOLUTION: The power transmission unit 100, which is fitted to a power transmission shaft 15 rotatable in a predetermined direction and moderates non-constant velocity of the power transmission shaft 15, includes: an input side rotator (clutch 50) provided with an input side locking part (input side clutch pawl 53) at a cylindrical part 51 fitted to the power transmission shaft 15 and rotating together with the power transmission shaft 15 an output side rotator (sprocket 60) fitted with the cylindrical part 51 so that the cylindrical member 51 of the input side rotator as a rotation shaft can be freely rotated and provided with an output side locking part (output side clutch pawl 63) capable of meshing with the input side locking part and a biasing member (torsional coil spring 70) for biasing the output side rotator in the rotation direction. The input side rotator and the output side rotator are capable of relatively rotating within a predetermined angle range.COPYRIGHT: (C)2013,JPO&INPIT【課題】動力伝達軸の劣化を抑制する動力伝達ユニットを提供すること。【解決手段】所定方向に回転可能な動力伝達軸15に嵌合され、動力伝達軸15の不等速回転を緩和する動力伝達ユニット100であって、動力伝達軸15に対して嵌合され動力伝達軸15とともに回転する円筒状部51に入力側係止部(入力側クラッチ爪53)が設けられた入力側回転体(クラッチ50)と、入力側回転体の円筒状部51を回転軸として回転自在となるように円筒状部51が挿嵌され、入力側係止部に噛合可能な出力側係止部(出力側クラッチ爪63)が設けられた出力側回転体(スプロケット60)と、前記出力側回転体を回転方向に付勢する付勢部材(捩りコイルバネ70)と、を備え、前記入力側回転体と前記出力側回転体とは、所定の角度の範囲で相対的に回転可能であること。【選択図】図9
