Throttle body module having improved blade to ledge sealing

摘要

A throttle body (11) has a through-bore (18), a circular throttle blade (20) of nominal uniform thickness is disposed within the through-bore and on a cylindrical shaft (22). The through-bore has two generally semi-circular ledges (56, 58) spaced upstream and downstream respectively from an imaginary flat plane that contains the shaft axis, each at a distance substantially equal to one-half the blade thickness. One ledge occupies essentially one semi-circumference of the through-bore for sealing with one of the opposite semi-circular perimeters of the throttle blade when the blade is closed, and the other occupies essentially an opposite semi-circumference of the through-bore for sealing with the other semi-circular perimeter of the blade when the blade is closed. The downstream ledge (56) has an upstream facing surface that is flat and perpendicular to the longitudinal axis, and the upstream ledge (58) has a downstream facing surface that departs slightly from a planar one that is flat and perpendicular to the longitudinal axis so as to conform the upstream ledge to a like slight departure in shape of the corresponding semi-circular perimeter of the blade due to engine intake vacuum when the blade (20) is closed. <IMAGE>