The present invention relates to a turbocharger.
Conventionally, turbochargers have been used, which utilizes kinetic energy of exhaust gas discharged by internal combustion engines to supercharge air to the engines. A typical turbocharger includes a turbine located in the exhaust system of an internal combustion engine and a compressor located in the intake system of the engine. When drawn into the turbine, exhaust gas discharged by the engine rotates the turbine impeller in the turbine. The turbine impeller is coupled to a compressor impeller located in the compressor. Thus, rotation of the turbine impeller rotates the compressor impeller. When the compressor impeller rotates, air drawn in through the compressor inlet is compressed and then delivered to the diffuser passage arranged outward of the compressor impeller. The air is subsequentlysurface. Accumulation of oil and the like reduces the area of the diffuser passage, reducing the performance and operating characteristics of the turbocharger.
Japanese Patent No. 5359403 discloses a configuration in which a cooling passage is provided in the wall of a compressor housing member. Fluid that flows through the cooling passage cools the diffuser surface, thereby lowering the temperature of the diffuser surface. Accordingly, the temperature of the diffuser surface is kept lower than the temperature at which oil and the like are solidified. This limits solidification of oil and the like on the diffuser surface.
In the above described conventional configuration, when blow-by gas is drawn into the intake passage, water vapor in the blow-by gas freezes depending on the temperature of the air drawn into the compressor,