ELECTRIC POWER STEERING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent outflow of a ball to the track outside of a ball screw track in a ball screw mechanism. SOLUTION: First hole 13a and second hole 13b for inserting a circulator are punched in mid-way of a spiral groove 12 formed on an inner periphery 7b of a ball nut 7. An intermediate groove passage 12a between the first hole 13a and the second hole 13b becomes a range of the ball screw track L1 for circulating the ball. Other ranges become first track outside L2 and second track outside L3. By making a groove depth of the intermediate groove passage 12a deeper than those of a first groove passage 12b of the first track outside L2 and a second groove passage 12c of the second track outside L3, the outflow of the ball to the groove passages 12b and 12c of each of the track outsides L2 and L3 from the intermediate groove passage 12a is prevented. COPYRIGHT: (C)2005,JPO&NCIPI