| 摘要 |
PURPOSE:To reduce a magnitude of forces necessary for operating a carburettor, by allowing a negative pressure chamber and an atmospheric pressure chamber to communicate each other via an air passage having a throttle section therein, in a carburettor adapted to utilize an external means in controlling an opening amount of a sliding throttle valve which rises upwardly in opposition against a negative pressure in a suction air tube. CONSTITUTION:A constant vacuum type carburettor is partitioned into a negative pressure chamber 4 and an atmospheric pressure chamber 5 by means of a pressure receiving section 3 provided above a sliding throttle valve 2 which is caused to rise upwardly via the pressure receiving section 3 by a negative pressure in a suction air tube 6, the negative pressure being introduced from a passage 7 into a negative pressure chamber 4. An upper limit of this throttle valve 2 is defined by a control board 8 which is operated from an external means. In such an arrangement as mentioned above, the negative pressure chamber 4 and the atmospheric pressure chamber 5 are communicated each other by an air passage 11 having a throttle section therein. At a time of the throttle valve 2 raising upwardly under such a condition that a negative pressure is so high as to suck the throttle valve 2 onto the control board 8, an air contained inside the negative pressure chamber 4 is caused to shift into the atmospheric pressure chamber 5 via the air passage 11. Reversely, when the throttle valve 2 lowers downwardly, the air is caused to shift from the atmospheric air chamber 5 into the negative pressure chamber 4 via the air passage 11. |
