| 摘要 |
PROBLEM TO BE SOLVED: To provide a turbine housing with a water-cooling jacket capable of preventing degradation of supercharging efficiency by minimizing reduction of thermal or kinetic energy due to excessive cooling of an exhaust gas flowing in an exhaust gas flow channel, and reducing an amount of cooling water circulated in the water-cooling jacket.SOLUTION: A turbine housing includes a scroll body portion 10 forming an exhaust gas flow channel inside thereof, and shells 21, 22 disposed outside of the scroll body portion 10 and defining and forming a water-cooling jacket 23 with an outer wall surface of the scroll body portion. The scroll body portion 10 is composed as a casting composed of an iron-based material. Surface texture of the outer wall surface 15 of the scroll body portion facing the water-cooling jacket 23 is determined to be rougher than surface texture of an inner wall surface 17 of the scroll body portion facing the exhaust gas flow channel 12. Preferably, the surface texture of the outer wall surface 15 of the scroll body portion is determined to be arithmetic average roughness Ra=25 μm or more.SELECTED DRAWING: Figure 7 |
