Sensor magnet device, gear mechanism and speed reducing electric motor

摘要

In a speed reducing electric motor (10), a speed reducing gear unit (14) has a sensor magnet device (100), which is fixed to a worm wheel (22) and includes an inner ring magnet (102), an outer ring magnet (104) and connecting portions (106). The inner ring magnet (102) is placed along a predetermined first imaginary circle. The outer ring magnet (104) is placed along a predetermined second imaginary circle, which is coaxial with the first imaginary circle and has a diameter that is smaller or larger than that of the first imaginary circle. The connecting portions (106) connect between the inner ring magnet (102) and the outer ring magnet (104). The sensor magnet device (100) is fixed to.the worm wheel (22) by a magnet fixing structure (50, 72).