| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust control valve that complies with both requirement for reduction of noises required at low speed engine operation and requirement for reduction of low back pressure required at high speed engine operation, without having a valve seat portion enlarged in radial directions. SOLUTION: On a contact surface of a body 21 at a valve element 2 serving as a point of application of pressing force from a coil spring 4, a protrusion 6 is formed in a substantial angle shape, having an upwardly inclined surface 6a that guides and moves the point of application of the pressing force from the coil spring 4 on the body 21 in a direction of increasing the apparent pre-torque of the coil spring 4 against the body 21 of the valve element 2 in the early stage of opening an exhaust control valve A, and having a downwardly inclined surface 6b, reversely after climbing over the upwardly inclined surface 6a, that guides and moves the point of application of the pressing force by the coil spring 4 on the body 21 in the direction of lowering the apparent pre-torque of the coil spring 4 against the body 21. COPYRIGHT: (C)2005,JPO&NCIPI
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