Patent ID: 7513507

Claim:
A flexible boot for a constant velocity universal joint, comprising: a smaller-diameter mounting portion provided at one end and adapted to be mounted on a shaft member of the constant velocity universal joint; a larger-diameter mounting portion provided at the other end and adapted to be mounted on an outer ring of the constant velocity universal joint; and a bellows portion having one or more crests and valleys being provided between both of said mounting portions, wherein said larger-diameter mounting portion and said bellows portion are connected to each other by a straight portion constructed by an inclined cylindrical portion which is rectilinear in section and has a diameter continuously and gradually reduced from said larger-diameter portion to said bellows portion, wherein said smaller-diameter mounting portion and said bellows portion are connected to each other by a straight portion constructed by an inclined cylindrical portion which is rectilinear in section and has a diameter continuously and gradually reduced from said bellows portion to said smaller-diameter mounting portion, wherein an axial distance of each of said straight portions is equal to or larger than 20% of an entire axial distance from a boundary between the larger-diameter mounting portion and the adjacent straight portion to a boundary between the smaller-diameter mounting portion and the adjacent straight portion, so that said bellows portion is located substantially centrally in an axial direction between both of said straight portions, and wherein an axial distance of said bellows portion is in a range of 20% to 60% of said entire axial distance.