To provide a normal pressure valve mechanism 30 capable of simplifying a manufacture of a case body 12 and preventing an abnormal noise accompanying a slight vibration at a stable opening/closing characteristic.
The normal pressure valve 30 is provided with a flow passage formed in a case body 12; a seal projection 28c at a normal pressure side formed facing to this flow passage; a normal pressure valve element 34 for closing the flow passage by seating on the seal projection 28c at a normal pressure side; and a normal pressure spring 31 for urging it to the direction of seating on the normal pressure valve element 34. A flexible contact piece 34h projected provided at a smaller thickness than that of an annular projection 34c and contacted with the case body 12 side is provided on an outer periphery of the normal pressure valve element 34. This contact piece 34h is contacted with a support edge 28g near a valve open pressure of the normal pressure valve element 34 to prevent a slight vibration.
NISHI HIROSHI
NAKAGAWA MASAYUKI
