Patent ID: 6912993

Claim:
A throttle system, having a throttle body, wherein a through hole is formed to receive one end of the shaft of a throttle valve to be inserted there-through, a bearing recession, with a diameter larger than the through hole, for installing a bearing that supports the shaft, to allow the shaft to rotate, is formed outside the through hole, and an enlarged recession, that is larger than the through hole, is formed between the through hole and bearing recession; a bearing that is installed in the recession so as to support the shaft to allow the shaft to rotate; and a seal structure, which is provided at an area including the through hole or an area including the boundary between the enlarged recession and the through hole, wherein said seal structure forms a doughnut shape having the through hole therein of which a diameter is equal to or larger than, but nearly equal to, a diameter of said shaft of said throttle valve to prevent air leakage between an upstream and a downstream side of said throttle valve.