Valves are used in myriad systems and environments, and may be operated in numerous and varied ways. Some valves are manually operated, others are operated via electrical, hydraulic, pneumatic, or various other types of actuators. In one particular implementation, a flow control valve is installed in an aircraft environmental control system. In such an implementation, the flow control valve is operated via a pneumatic actuation device that will open the flow control valve upon receipt of pressurized air upstream of the flow control valve. It may additionally be desirable, in such implementations, that the flow control valve include a shut-off mechanism that prevents downstream flow ducts from reaching or exceeding a particular pressure.
There is presently a desire for a control valve, which may be used in an aircraft environmental control system, that is normally-closed, is capable of being opened with pressure from either upstream or downstream of the control valve, is capable of being closed upon receipt of a suitable electrical signal, implements a backup means of closing if the electrical signal is not received, and is able to in the event that upstream pressure exceeds the electrical or backup closing setpoint. Unfortunately, there is no known valve that implements all of these functions.
Hence, there is a need for a flow control valve that implements the functionality described above. The present invention addresses at least this need.