Throttle valve opening and closing device

A motor driving type throttle valve device comprising:

• a throttle body for constructing an intake air passage of an internal combustion engine;
• a throttle shaft supported rotatably at said throttle body;
• a throttle valve provided at said throttle shaft, for rotating in said intake air passage and varying an opening area of said intake air passage;
• a motor for rotating and driving said throttle valve;
• a reduction mechanism constructed and included a motor gear provided at an output shaft of said motor and a throttle gear provided at said throttle shaft;
• a spring for biasing said throttle valve from a rotating end position of said throttle valve toward a rotating start position;
• and
• a stopper for limiting a movement of said throttle valve at said rotating start position;
• wherein a sectional area of said intake air passage which is determined by said throttle valve and said intake air passage at a position of said stopper is formed as a sectional area of said intake air passage for being able to secure a necessary air amount for a self run of a vehicle.