Recirculation systems for engine intake air are disclosed having a turbocharger compressor with an inlet and an outlet, a recirculation pathway connecting fluid flow from the outlet of the turbocharger compressor to fluid flow into the inlet of the turbocharger compressor, and a recirculation valve assembly controlling fluid flow through the recirculation pathway. The recirculation valve assembly includes an actuator operating a valve coupled to an aspirator assembly that produces vacuum when the fluid flows through the recirculation pathway from the inlet to the outlet and when fluid flows through the recirculation pathway from the outlet to the inlet. Fluid flows through the recirculation pathway from the outlet to the inlet when the turbocharger generates boost. The vacuum generated by the aspirator assembly is in fluid communication with the actuator to move the valve between two or more positions.

An air control valve for a fuel cell vehicle includes: a valve housing formed with air flow paths; valve members configured to selectively open or close the air flow paths; and a drive unit configured to rectilinearly operate the valve members so that the valve members rectilinearly move from a first position at which the air flow paths are closed to a second position at which the air flow paths are opened, such that it is possible to obtain an advantageous effect of improving sealing performance and improving stability and reliability.

An air control valve for a fuel cell vehicle includes: a valve housing formed with air flow paths; valve members configured to selectively open or close the air flow paths; and a drive unit configured to rectilinearly operate the valve members so that the valve members rectilinearly move from a first position at which the air flow paths are closed to a second position at which the air flow paths are opened, such that it is possible to obtain an advantageous effect of improving sealing performance and improving stability and reliability.

A pressure type flow rate control apparatus is provided wherein flow rate of fluid passing through an orifice is computed as Qc=KP1 (where K is a proportionality constant) or as Qc=KP2.sup.m (P1-P2).sup.n (where K is a proportionality constant, m and n constants) by using orifice upstream side pressure P1 and/or orifice downstream side pressure P2. A fluid passage between the downstream side of a control valve and a fluid supply pipe of the pressure type flow rate control apparatus comprises at least 2 fluid passages in parallel, and orifices having different flow rate characteristics are provided for each of these fluid passages, wherein fluid in a small flow quantity area flows to one orifice for flow control of fluid in the small flow quantity area, while fluid in a large flow quantity area flows to the other orifice for flow control of fluid in the large flow quantity area.

A double port regulator assembly includes a first fluid port and a second fluid port. A fixed valve seat assembly is disposed proximate the first fluid port and a floating valve seat assembly is disposed proximate the second fluid port. A first valve plug cooperates with the fixed valve seat assembly to open and close the first fluid port and a second valve lug cooperates with the floating valve seat assembly to open and close the second fluid port. The floating valve seat assembly includes a floating valve seat that is movable with respect to the fixed valve seat.