Patent ID: 7451854

Claim:
An exhaust flow rate control valve comprising: an exhaust pipe which is provided in an exhaust system for an engine and which includes an inner pipe member through which exhaust gas is passed and an outer pipe member surrounding the inner pipe member; an on-off valve provided in the inner pipe member and switched between a closed state in which a flow passage sectional area of the inner pipe member is decreased, and an opened state in which the flow passage sectional area is increased; and a resilient member disposed between the inner pipe member and the outer pipe member so as to bias the on-off valve in a closing direction, the on-off valve being switched from the closed state to the opened state by an increase in pressure of the exhaust gas acting on the on-off valve against a biasing force of the resilient member, wherein a notch is formed in the on-off valve; a recess is formed in the inner pipe member to correspond to the notch; and the resilient member is disposed in a space formed between the recess and the outer pipe member.