| 摘要 |
PURPOSE:To achieve a high accurate control by previously specifying an initial conductive phase, first conducted with a current at the time of starting, with positioning of a stator in a step motor possible in the direction of rotation of a rotor, in the case of the step motor which drives a control valve for controlling an engine operative condition. CONSTITUTION:A throttle valve 3, provided in an intake system of an engine, is rotatably supported by a shaft 5 and urged in a fully-closing direction by a return spring 7. While the shaft 5 is connected, in the other end, to a rotary shaft 11 of a step motor 9. The step motor 9 is constituted of a rotor 19, comprising an iron core 21 and a permanent magnet 23, and a stator 25, comprising an iron core 27 and four layers of excitation windings 29, and driven by a phase-classified excitation current given to the excitation winding 29 from a control circuit 31. Now when the step motor 9 is started, for instance, the first and second phases are specified to the initial conduction phase, thus from a condition that the rotor 19 is returned to a stable point, a control can be started. |
