| 摘要 |
PURPOSE:To secure such a variable displacement turbocharger that is low cost and high performance by installing a fixed type swirl generating device which gives such a rotational swirl as getting away from a turbine rotor in and around an outlet to a nozzle part. CONSTITUTION:At time of low engine speed, an expansion ratio before and behind a throat part 7 or an inlet of a scroll chamber 3 is small as well as a turning pitch of a swirl locus D1 of the gas generated at a fixed type swirl generating device (helical passage 6) is small. A speed component in a direction of getting away from a turbine rotor 5 is large and thereby it becomes like the swirl locus E1 crushed in a radial outward direction in a nozzle part 2. At time of high engine speed, a gas swirl locus D2 is large in its turning pitch, whereby such an effect as crushing a flow of gas in the radical outward direction inside the nozzle part 2 becomes smaller so that it becomes like a swirl locus E2.
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