Patent ID: 6843223

Claim:
A tandem valve type throttle body comprising: a throttle valve which is attached to a throttle valve shaft, and opens and closes an intake passage interlocking with an accelerator operation; a throttle valve lever which is attached to the throttle valve shaft, and is energized in a closing direction of the throttle valve by a throttle valve return spring; a sub throttle valve which is attached to a sub throttle valve shaft, and opens and closes the intake passage in an upstream side from the throttle valve; a motor (M) which operates so as to open and close the sub throttle valve on the basis of a signal output from an ECU in response to an output signal from an opening degree sensor (T) for detecting a rotation angle of the sub throttle valve shaft; and a transmission member constituted by a link arm, a link lever and the like, which opens throttle valve toward a first idle opening degree at a high opening degree of the sub throttle valve, wherein a rotor spring (TC) which presses and engages the sub throttle valve shaft and a sensor rotor (TA) of the opening degree sensor (T) in a rotational direction is energized in an opening direction of the sub throttle valve, and a link lever spring which presses the transmission member to one direction is energized in a closing direction of the sub throttle valve, whereby a torque is set in such a manner as to cancel spring forces applied to the sub throttle valve shaft with each other.