| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a reduction gear couple capable of reducing the space and sharing a worm wheel for a right-hand-drive car and a left-hand-drive car, in an electric power steering device employing reduction gears of worm gears.SOLUTION: A first reduction gear 4 includes: a worm wheel 41 which is processed by a hob with a left twist direction and of which the lead angle is 0°; and a first worm 42 with a left twist direction, and an angle at which a worm axial line (n) of the first worm 42 crosses a worm wheel axial line (m) is defined as 90°+α°. A second reduction gear 104 includes the worm wheel 41 and a second worm 1042 with a right twist direction and an angle at which a worm axial line (n) of a second worm crosses the worm wheel axial line (m) is defined as 90°-β°. The angleβ° is set to a value smaller than that of the angleα° in order to prevent interference in a meshing part of the second worm 1042 and the worm wheel 41.</p> |
