To reduce noise by generating turbulence downstream of a throttle valve when the throttle valve is abruptly opened.
A throttle body 15 is attached to an engine through an intake manifold. A throttle valve 19 provided in an internal space 16 in the throttle body 15 is composed of a shaft 18 rotatably attached to the body 15, and a disc-like valve element 17 fixed to the shaft 18. A shoulder 32 is formed in the inner peripheral wall of the throttle body 15 over the entire periphery of the latter at a position which is downstream of the shaft 18 by a distance L1 from the center axis of the shaft 18. By forming the shoulder 32 over the entire periphery, an enlarged bore part 21 having an enlarged flow passage area can be formed in the throttle body 15. The distance L1 is set to be a half of the radius R of the valve element 17.
KATAHIRA NATSUHIKO
HASHIOKA HITOSHI
MOROTA KENJIRO
MIYAJI YOSHIHIRO
Next Patent: INTAKE DEVICE