Fluid supply apparatus

A fluid feeding apparatus comprising:

• first and second fluid passages each having a pressure flow controller therein for regulating fluid flow rate therethrough, said first and second fluid passages being joined at a downstream extent and connected to a consumer;
• first and second fluid changeover valves, disposed in said first and second fluid passages, respectively, in a downstream direction from the pressure flow controllers, for selectively opening and closing said fluid passages;
• said pressure flow controllers each including,
• an orifice,
• a control valve disposed on an upstream side of said orifice, said orifice being disposed in the fluid passage in an upstream direction from the fluid changeover valve,
• a pressure detector disposed between the control valve and the orifice, and,
• a calculation control unit for producing a control signal Qy for controlling the control valve, said calculation control unit calculating the control signal Qy according to the equation Qy=Qc−Qs, where Qc is a flow rate signal for the fluid passage in which one flow controller is located and Qs is a flow rate specifying signal for the fluid flow passage in which said one flow controller is located,
• a calculation control unit calculating the flow rate signal Qc for a given one of the fluid passages according to the equation Qc=KP1, where K is a constant, and P1 is a pressure in said given one fluid flow passage detected by the pressure detector;
• and,
• a fluid feeding control unit for applying the signals Qs to said first and second calculation control units and applying actuation signals to said first and second fluid changeover valves to open or close said fluid changeover valves, said fluid feeding control unit applying a signal Qs=0 to said first or second calculation control unit and concurrently applying an actuation signal to close said first or second fluid changeover valve,
• whereby the control valve in said first or second fluid passage is closed when the fluid changeover valve in the first or second passage, respectively, is closed.

A fluid feeding apparatus comprising:

• at least three pressure flow controllers arranged in parallel fluid passages to regulate fluid flow rates through said passages,
• fluid changeover valves provided to open and close respective fluid passages on the secondary sides of respective pressure flow controllers, and
• a fluid feeding control unit for controlling actuation of the pressure flow controllers and the fluid changeover valves,
• said pressure flow controllers each including:
• an orifice, a control valve disposed on an upstream side of said orifice, a pressure detector disposed between the control valve and said orifice, and a calculation control unit which inputs a drive for said control valve a difference between a flow rate signal Qc and a flow rate specifying signal Qs as a control signal Qy, said flow rate signal Qc calculated with the flow rate Qc=KP1, where K is a constant, on the basis of a pressure P1 detected by the pressure detector,
• wherein the flow rates on downstream sides of the orifices are controlled by regulating the pressures P1 on the upstream sides of the orifices through the opening and closing of the control valves,
• wherein said fluid passages are connected with each other and connected to a fluid consumer at downstream sides of said fluid changeover valves, and,
• wherein different kinds of fluids are fed to primary sides of said pressure flow controllers.