| 摘要 |
PURPOSE:To make the operation of a throttle valve smooth by forming a pressure receiving chamber between a disklike main throttle valve and a disklike subthrottle valve both of which move integrally up and down, and introducing the negative pressure at the downstream side of the throttle valve into the pressure receiving chamber, and further making the pressure receiving area of the pressure receiving chamber equal to that on the intake negative pressure receiving side. CONSTITUTION:A subthrottle valve 6 which is moved integrally up and down together with a main throttle valve 5 which is moved up and down from the outside is provided on the intake downstream side of the main throttle valve 5. The subthrottle valve 6 is always pressed toward the intake downstream side by a spring 9 placed inside a pressure receiving chamber 8 which is formed between the main throttle valve 5 and itself, and the pressure receiving chamber 8 is communicated with the intake passage on the downstream side of the throttle valve via a hole 6c on the subthrottle valve 6. Although the subthrottle valve 6 is attracted by the negative pressure at the downstream side of the throttle valve, said pressure is introduced into the pressure receiving chamber 8 so as to exert equal force in the opposite direction on the subthrottle valve 6, thus the subthrottle valve 6 can be moved up and down against the sliding friction caused by only the force of the spring 9.
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