| 摘要 |
PURPOSE:To precisely control intake air, by coupling a motor to the rear side of a piston valve which is slidable transversely of an engine intake-air passage, through a removable intermediate member which may be magnetically coupled to the rear side of the piston valve, thereby the atmospheric air is introduced into the rear side of the intermediate member to close the valve upon failure of the device. CONSTITUTION:An intermediate member 14 having a permanent magnet 18 at its front end is slidably fitted in the rear side of a piston valve 14 which is in turn slidably fitted in a cylinder part 13 opened to an intake-air passage 12 in an engine, and is coupled with a drive motor 16 to slide the piston valve for controlling the opening area of the intake air passage. A pressure chamber 25 formed between the piston valve 14 and the intermediate member 15 is communicated with an auxiliary pressure chamber 23 at the rear of the intermediate member 15 through a communication hole 21. Upon failure of the device, when a solenoid valve 26 is energized to open an atmospheric air introduction passage 15, the atmospheric air is introduced into the auxiliary pressure chamber 25 and the pressure chamber 20, and therefore, the piston valve 14 projects into the intake-air passage due to the pressure differential across a venturi section 12B and a spring 17, thereby the intake-air passage is fully closed. |
