摘要 |
PURPOSE:To enable to control the maximum supercharging pressure with ease and effectively in an apparatus comprising a plurality of turbochargers disposed in parallel with each other, by forming an exhaust by-pass passage by-passing all of turbines of each supercharger, and providing a supercharging pressure control valve in said exhaust by-pass passage. CONSTITUTION:A low-speed turbocharger 8 and a high-speed turbocharger 9 are constituted respectively by blowers 8a, 9a diposed in a first and a second branch intake passages 5, 6 formed in an intake passage 2 between an air-flow meter 4 and a throttle valve 7 in parallel with each other and turbines 8b, 9b disposed in a first and a second branch exhaust passages 10, 11 branched from an intermediate portion of an exhaust passage 3. In such an arrangement, a by-pass passage 21is formed for communicating an exhaust passage 3u located on the upstream side of the portion 3a where the two branch exhaust passages 10, 11 are branched with an exhaust passage 3d located on the downstream side of the same. Further, a supercharging pressure control valve 22 is provided at an intermediate portion of the by-pass passage 21. With such an arrangement, the maximum supercharging pressure is limited by opening the control valve 22 when the supercharging pressure becomes higher than a prescribed value. |