Pressure relief valve for blood pressure measuring instrument

Claim 1

A pressure relief valve for a blood pressure measuring instrument comprising a valve housing having a hollow space forming an air passage, a discharge mechanism on the housing for selectively discharging a small or large amount of compressed air through the air passage, the discharge mechanism including a valve seat consisting of an outwardly converging tapered hole providing communication between the air passage in the valve housing and the outside thereof, a valve member shiftable between a position in contact with the valve seat and a position apart therefrom, a head portion of the valve member protruding above a lower surface of said valve housing, a valve closing spring interposed between an upper surface forming a hollow space in the valve housing and the valve member, a recess formed in the valve housing, an adjustment screw plug threadedly interengaged with the recess and having exhaust holes formed therein, a push button disposed in the adjustment screw plug in a manner that the push button is permitted to move upward and downward for a restricted distance and can open or close the valve member in cooperation with the spring in contact with the head portion of the valve member, the adjustment screw plug being rotatable to push the push button downwardly thereby making it possible to automatically discharge small amounts of compressed air at the decrease during the measurement of blood pressure, and direct pushing of the push button causing the remaining cuff pressure to quickly discharge after the measurement of blood pressure.