| 摘要 |
PURPOSE:To reduce noise due to combustion, by providing a delay mans for delaying the formation of swirl at least when a low load high rotation region is shifted to a low load low rotation region where a swirl variable means for forming swirl in the low load low rotation region is provided. CONSTITUTION:An air intake passage 7 for supplying intake air to the combustion chamber 2 of an engine 1 is divided into first and second passages 7a, 7b in the vicinity of an intake port 3 and the first passage 7a is provided with a shutter valve 8. The second passage 7b has a cross-sectional area smaller than that of the first passage 7a and has an opening at its downstream end opened toward the circumferential direction of the combustion chamber 2. In the air intake device with such an arrangement, a delay unit 11 comprising an orifice 13 and a check valve 14 disposed in parallel are interposed in a passage 12 for introducing the negative pressure of the intake air into the negative pressure chamber 9b of a diaphragm unit 9 for actuating the shutter valve. With this arrangement, when a low load high rotation region is shifted to a low load low rotation region, swirl is formed gradually for preventing an abrupt increase in noise due to combustion.
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