Turbine and turbocharger having the same

A turbine comprising:

• a turbine rotor which has turbine blades;
• a housing which accommodates the turbine rotor and whose cross-sectional area of a scroll portion formed between the housing and the turbine rotor gradually decreases;
• a plurality of fixed vanes which are fixed along a curved line dividing the scroll portion into an inner scroll part and an outer scroll part;
• communicating parts which are formed between the adjacent fixed vanes and communicate between the inner scroll part and the outer scroll part;
• and a switch valve which switches a flow path in the housing either to the inner scroll part or to both the inner scroll part and the outer scroll part, wherein flow path areas of the communicating parts are reduced in a downstream direction of the scroll portion, wherein chord lengths of the fixed vanes are increased in the downstream direction of the scroll portion.

A turbine comprising:

• a turbine rotor which has turbine blades;
• a housing which accommodates the turbine rotor and whose cross-sectional area of a scroll portion formed between the housing and the turbine rotor gradually decreases;
• a plurality of fixed vanes which are fixed along a curved line dividing the scroll portion into an inner scroll part and an outer scroll part;
• communicating parts which are formed between the adjacent fixed vanes and communicate between the inner scroll part and the outer scroll part;
• and
• a switch valve which switches a flow path in the housing either to the inner scroll part or to both the inner scroll part and the outer scroll part,
• wherein an absolute value of a rate of change of A/R with respect to a fluid flow direction at a first position is made larger than an absolute value of a rate of change of A/R with respect to the fluid flow direction at a second position located at a downstream side of the first position, where A indicates a flow path area of the outer scroll part and R indicates a distance from a flow path center of the outer scroll part to a rotation center of the turbine rotor.