Patent ID: 7363835

Claim:
A ball screw apparatus, comprising: a screw shaft having a screw groove in a spiral shape at an outer peripheral face thereof; a nut having a screw groove in a spiral shape in correspondence with the screw groove of the screw shaft at an inner peripheral face thereof and screwed to the screw shaft, the nut having holes formed at an outer peripheral portion thereof; a number of balls rollably charged into a rolling passage that is defined by the screw groove of the screw shaft and the screw groove of the nut; and a ball circulating member formed substantially in a U-like shape and having end portions to be fitted to the holes to infinitely circulate the balls by scooping up the balls rolling on the rolling passage at a middle thereof and returning the balls to the rolling passage; wherein the ball circulating member comprises a side cap which includes leg portions at both end portions thereof to be fitted into the holes, each of the leg portions containing at least one of a scooping up path for scooping up the balls and a returning path for returning the balls, the scooping up path and the retuning path being inclined with respect to respective outer peripheral faces of the leg portions; the holes include a slot substantially in parallel with directions of the screw grooves of the screw shaft and the nut; and the scooping up path and the returning path are directed substantially in a tangential direction of the screw shaft and inclined substantially toward a lead angle direction of the screw grooves of the screw shaft and the nut.