| 摘要 |
An electronically-controlled throttle body includes a throttle valve having a valve disc, fixed on a valve shaft rotatably supported in a body inside which an air-intake passage is formed, for varying an opening area of the air-intake passage; a reduction gear mechanism connected to the valve shaft of the throttle valve; and a motor connected to the reduction gear mechanism; rotational drive power from the motor is transmitted to the valve shaft via the reduction gear mechanism, and the opening area of the air-intake passage is varied by rotatably moving the valve disc. The reduction gear mechanism includes a planetary gear mechanism and a spur gear reduction gear mechanism, rotational drive power from the motor is decelerated by the planetary mechanism, and the decelerated rotational drive power is further decelerated by the spur gear reduction gear mechanism, and then transmitted to the valve shaft.
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