Intake air control apparatus for internal combustion engine

An intake air control apparatus for an internal combustion engine, said apparatus comprising:

• a throttle valve for adjusting an amount of intake air introduced into the combustion chamber of the internal combustion engine;
• a rotary drive member for driving the throttle valve in the directions toward a full-open position and a closed-up position;
• a coil spring for activating the throttle valve in the directions toward the closed-up position and the full-open position;
• a throttle bore for accommodating the throttle valve rotatably, and a throttle body having a recessed housing adjacent to the throttle bore;
• a housing cover forming a space for accommodating the rotary drive member and the coil spring with the housing, the housing cover having a coupling end surface adapted to be coupled to the opening-side end surface of the housing;
• and
• a throttle opening degree adjustment mechanism for adjusting the throttle opening degree corresponding to the rotational angle of the throttle valve to a set opening degree associated with predetermined operating conditions of the internal combustion engine;
• wherein the housing and the housing cover are formed of resin;
• wherein a selected one of the rotary drive member and the coil spring has a contact portion rotated integrally with the throttle valve;
• wherein the throttle opening degree adjustment mechanism includes a sleeve nut having an internal female screw hole along the axial line and fixedly held between the opening-side end surface of the housing and the coupling end surface of the housing cover, and a throttle opening degree adjustment screw screwed retractively into the female screw hole of the sleeve nut and coming into direct contact with the contact portion when the throttle opening degree is located within a set opening degree range thereby to restrict the rotation of the throttle valve to the set opening degree.