| 摘要 |
PURPOSE:To obtain the magnetic shield cover very small in a torque ripple and large in a magnetic shield effect by a method wherein an opening angle of a notch formed on the peripheral side surface of the shield cover is made nonintegral multiples of a magnetic pole divided angle of a rotor magnet. CONSTITUTION:A notch opening 81 for inserting a printed substrate 11 is formed on the peripheral side surface of the cup-shaped magnetic shield cover 8. The opening angle psis of the opening 81 is set to (n+3/4) times the magnetic pole divided angle psin of the rotor magnet 1. Thus, a reluctance force working between the opening 81 and the rotor magnet 1 can extremely be decreased by setting the opening angle psis of the opening 81 to a value satisfying the angle of [n+(2/3-3/4)] times the magnetic pole divided angle psin, [n-(1/4-1/3)] times, (n=1, 2, 3...), or nearly similar to the angle psin. Thereby contriving the decrease of the magnetic shield effect. |
