EXHAUST GAS PASSAGE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust gas passage for an internal combustion engine has an exhaust gas throttle valve, a bypass passage, and a waste gate valve. The exhaust gas throttle valve is a butterfly type exhaust gas throttle valve pivotable to change the cross-sectional area of the exhaust gas passage. The bypass passage connects that portion of the exhaust passage which is on the upstream side, in the direction of exhaust gas flow, of the exhaust gas throttle valve to that portion of the exhaust gas passage which is on the downstream side. The waste gate valve is provided in the bypass passage and can change the cross-sectional area of the bypass passage.When the exhaust gas throttle valve is in a specific operation state, the waste gate valve opens the bypass passage. A downstream side opening end of the bypass passage is opened only at that portion of the inner wall face of the exhaust gas passage which circumferentially corresponds to a point intersecting with the axis of a pivot shaft. The width of the opening end, which width is measured in the direction intersecting the direction of exhaust gas flow perpendicularly, is smaller on the downstream side than on the upstream side.