| 摘要 |
An exhaust gas throttle valve disposed in the exhaust system of an engine, wherein the center axis of rotation of a valve shaft 5 is set at a position deviated from the center axis of the exhaust gas passage, and two recessed portions 11 are symmetrically formed in the circumferential portion of a valve body 4 by cutting the surface thereof. The positions where the recessed portions 11 are formed are on the side of the center axis of the exhaust gas passage beyond the center axis 12 of rotation, and at where the peripheral portion of the valve body 4 faces the edge portions 9 where insertion holes 8 for the valve shaft 5 are opened in the exhaust gas passage. At these positions, the distance is a minimum between the peripheral portion of the valve body 4 and the edge portions 9 . The recessed portions 11 work to increase the gap relative to the edge portions 9 at that positions. It is therefore made possible to approximate the peripheral portion of the valve body 4 to the tubular wall of the exhaust gas passage 2 when the exhaust gas throttle valve is closed preventing the valve body 4 and the edge portions 9 from coming in contact together despite of the thermal expansion. |
