| 摘要 |
PURPOSE:To improve drivability in restoring fuel cutout for speed reduction and prevent a rise in engine speed and the like in a cold condition by closing a control valve located in an air introduction passage through turning 'ON' an idle switch and the like in a non-fuel cutout condition. CONSTITUTION:A supercharger comprising a Roots vacuum pump is so arranged as to be freely rotatable, with the rotor shafts 22 and 23 of two rotors 21 and 40 supported on a bearing 28 within housings 50 and 51. In the aforesaid constitu tion, a circular space part 47 formed around the rotor shafts 22 and 23 and between the end surfaces of the rotors 21 and 40 and the sealed part 27 of the bearing 28, is made continuous to the atmosphere via air introduction passages 7, 8 and 48, and a control valve 9 is provided in way of said passages 7, 8 and 48. And when an idle switch is 'ON' or the number of engine revolutions is under a predetermined value in a non-fuel cutout condition, the control valve 9 is closed. According to the aforesaid constitution, drivability is improved at the restoration of fuel cutout for speed reduction and a rise in engine speed is prevented in a cold condition.
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