Throttle valve opening and closing apparatus for a vehicle, and vehicle internal combustion engine using the apparatus

摘要

When the power source of a motor is turned off, a cam connected to the motor is held at an initial default stopping position by a return spring generating a torque in one direction and a throttle valve connected to a cam via an arm, and a valve gear is held at a corresponding default opening position. When the motor rotates and generates its torque, the arm first closes the throttle valve to a prescribed minimum opening and then opens the throttle valve in the fully open direction.