POWER TRANSMISSION SHAFT

To enhance strength of a power transmission shaft.SOLUTION: A power transmission shaft comprises: a fixed type constant velocity universal joint 1 comprising an outside joint member 6, an inside joint member 7, and a ball 8; a sliding type constant velocity universal joint 2 comprising an outside joint member 10, an inside joint member 11, and a roller 12; and a shaft 3 inserted into inner peripheries of the inside joint members 7 and 11 of the constant velocity universal joints 1 and 2. Female splines 20 formed in inner peripheral surfaces of the inside joint members 7 and 11 and male splines 4 formed in outer peripheral surfaces of the shaft 3 are fitted together. In cross sections orthogonal to an axial direction, contact points P between tooth surfaces 4a of the male splines 4 and tooth surfaces 20a of the female splines 20 are arranged closer to an outside diameter side than tooth height direction center parts M of the male splines 4.SELECTED DRAWING: Figure 2 【課題】動力伝達シャフトの強度を高める。【解決手段】動力伝達シャフトは、外側継手部材６、内側継手部材７、及びボール８を有する固定式等速自在継手１と、外側継手部材１０、内側継手部材１１、及びローラ１２を有する摺動式等速自在継手２と、両等速自在継手１、２の内側継手部材７、１１の内周に挿入されたシャフト３とを備える。内側継手部材７、１１の内周面に形成された雌スプライン２０と、シャフト３の外周面に形成された雄スプライン４とが嵌合している。軸方向と直交する断面において、雄スプライン４の歯面４ａと雌スプライン２０の歯面２０ａとの接触点Ｐが、雄スプライン４の歯丈方向中央部Ｍよりも外径側に配される。【選択図】図２