Stepping motor and intake control apparatus therewith

摘要

An intake air quantity control apparatus for use in a motor vehicle for controlling an intake air quantity introduced into an engine of the motor vehicle by controlling the opening degree of a throttle valve provided in an air intake passage of the engine. The intake air quantity control apparatus includes a stepping motor connected to the throttle valve and operatively coupled to an accelerating pedal of the motor vehicle so that the stepping motor drives the throttle valve in response to depression of the accelerating pedal. The stepping motor is arranged to be further controllable in response to a control signal from a control unit of the motor vehicle and thus comprising a stator having a plurality of magnetic poles and a plurality of windings respectively wound around the magnetic poles and excited by the control signal, a first rotor rotatable with respect to the stator in response to excitation of said windings of said stator, and a second rotor disposed between the stator and the first rotor. The second rotor is arranged so as not to receive a rotational torque with respect to the stator in response to the excitation of the windings and to allow transmission of magnetic fluxes from the stator to the first rotor.