Patent ID: 8256570

Claim:
An exhaust flow control device for an exhaust muffler, comprising: a short-cut hole provided in an intermediate portion in a longitudinal direction of a downstream exhaust pipe connected to a muffler body, the downstream exhaust pipe having one end portion communicating with an inside of the muffler body and having an opposite end portion opened to atmospheric air, the short-cut hole allowing communication between the inside of the muffler body and an inside of the intermediate portion of the downstream exhaust pipe; and an exhaust flow control valve appended to the downstream exhaust pipe and configured to close the short-cut hole when a pressure in the muffler body is lower than a predetermined value, and open the short-cut hole when the pressure is at the predetermined value or higher, wherein the exhaust flow control valve comprises: a valve plate hinged to the downstream exhaust pipe in such a manner as to be pivotable, inside the downstream exhaust pipe, between a fully closed position where the short-cut hole is closed and a fully open position where the short-cut hole is opened, the valve plate having a tip end directed toward a downstream side of the downstream exhaust pipe when at the fully open position; a spring receiving member provided to the downstream exhaust pipe in such a manner as to traverse the short-cut hole; and a valve spring having one end portion fastened to a tip end portion of the valve plate, the tip end portion being located on the downstream side of the downstream exhaust pipe with respect to the spring receiving member, and having an opposite end side being in pressure contact with the spring receiving member in a slidable manner, thereby generating a repulsive force to bias the valve plate toward the fully closed position.