| 主权项 |
1. A flow direction restriction valve mechanism unit attachable to a valve device including a flow path in which a fluid passes and an open/close valve switching an open state to a close state or vice versa at a middle portion of the flow path, the flow direction restriction valve mechanism unit being attachable to a restriction valve attachment space formed on the side of a fluid inlet/outlet portion with respect to the open/close valve in the flow path so as to prevent the fluid from flowing in an unintended direction, the flow direction restriction valve mechanism unit comprising:
a first flow direction restriction valve that is located to be freely advance or retract to a first valve close position or a first valve open position in the restriction valve attachment space and retracts toward the first valve open position by a pressure of the fluid flowing in the flow path; a second flow direction restriction valve that is located to be freely advance or retract to a second valve close position or a second valve open position with respect to the first flow direction restriction valve and retracts toward the second valve open position by a pressure of the fluid flowing in the flow path; an acting gas flow path formed to cause the fluid of a predetermined pressure to flow to act on the first flow direction restriction valve such that the first flow direction restriction valve moves in an advancing direction from the first valve open position toward the first valve close position; a safety flow path that is connected with a middle part of the acting gas flow path and is in communication with the outside of the valve device; a safety valve located to be freely advance or retract to a third valve open position at which the acting gas flow path and the safety flow path are in communication with each other or to a third valve close position at which the acting gas flow path and the safety flow path are blocked against each other; a first urging portion having a spring force that urges the first flow direction restriction valve in a valve opening direction from the first valve close position toward the first valve open position and moves the first flow direction restriction valve from the first valve open position toward the first valve close position against the urging in the valve opening direction by a pressure, higher than, or equal to, a first predetermined pressure, of the fluid flowing in the acting gas flow path and acting on the first flow direction restriction valve; a second urging portion having a spring force that urges the second flow direction restriction valve in a valve closing direction from the second valve open position toward the second valve close position and moves the second flow direction restriction valve from the second valve close position toward the second valve open position against the urging in the valve closing direction by a pressure higher than, or equal to, a second predetermined pressure, which is lower than the first predetermined pressure; and a third urging portion having a spring force that urges the safety valve in a valve closing direction from the third valve open position toward the third valve close position and moves the safety valve from the third valve close position toward the third valve open position against the urging in the valve closing direction by a pressure higher than, or equal to, a third predetermined pressure, which is higher than the first predetermined pressure. |
