Flow regulating apparatus for a fluid, in particular a pneumatic choke valve

A flow regulating apparatus for a fluid, in particular a pneumatic choke valve, comprising:

• a housing having an inlet port and an outlet port fluidly connected by a passageway;
• and
• a throttling piston disposed in the passageway for movement in longitudinal direction between an initial position and an end position, said throttling piston including a curved tapered section to define with the passageway an overflow passage whose cross section is dependent on a position of the throttling piston, wherein the tapered section is configured such that a movement of the throttling piston from the initial position to the end position results in a progressive increase of the cross section of the overflow passage, wherein the throttling piston has three length portions which are defined by a leading cylindrical portion having an outer diameter, which is smaller than an inner diameter of the passageway to thereby bound an annular gap to form the overflow passage in the area of the initial position, a central portion adjoining the cylindrical portion and including an initial zone of a curved tapered section define the progressively increasing cross section of the overflow passage, and an end portion having a conical configuration defined by a steep cone angle for utilization a greatest possible pressure drop between the inlet port and the outlet port.