| 摘要 |
PURPOSE:To reduce the effect on an air flow volume caused by the irregularity in a metering valve by a method wherein an adjusting opening is formed in such a way that an adjusting of throttling is made to be increased or decreased in inverse proportion to a throttling clearance of a throttle valve at a closing position of the throttling valve. CONSTITUTION:A damper 7 occupies a position (d) under its open condition and occupies a position (a) under its closed condition. In case that the damper is not closed completely by an angle of theta1, a throttling clearance t1 between the damper 7 and a damper barrel 3 becomes larger than a throttling clearance t0 at a predetermined position, resulting in making a large volume of passing air. However, an adjusting clearance A1 for the adjusting opening 10 becomes smaller than A0 when it is set at its predetermined position, a volume of adjusting air passing through the adjusting clearance A1 becomes low and a volume of suction air at the suction port 12 in a blower 1 is made equal to that of the predetermined position (a). With this arrangement, an effect on air volume caused by the irregularity of the throttling valve is reduced.
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