| 摘要 |
PROBLEM TO BE SOLVED: To reduce flowing resistance of idle air without increasing processing and working man-hours while satisfying flow rate control characteristics required of an idle adjusting valve. SOLUTION: In this throttle system, an idle adjusting valve is mounted on a throttle body 151, comprising an upstream-side bypass passage 391 communicating with an intake passage on the upstream side of a throttle valve 18, a valve hole 42 with one end communicating with the upstream-side bypass passage, a valve chamber 371 communicating with the other end of the valve hole, a valve seat surrounding an opening of the other end of the valve hole, and a downstream-side bypass passage connecting the valve chamber with the intake passage at the downstream of the throttle valve 18. A cored hole 661 and a valve hole guide portion 69 are formed by a casting mold, during cast molding of the throttle body 151, from the a contact surface 15a1 side of the throttle body 15 to an intake tube member. The cored hole 661 forms at least part of the upstream bypass passage 391, Further, the valve hole guide portion 69 is constructed such that the distance from the center of the valve hole 42 is gradually decreased in a direction from the cored hole 661 to the valve chamber 371 along the opening edge of the valve hole 42 to the cored hole 661. |
