Flow control valve with venturi

A device for controlling flow through a conduit, the device comprising:

• a venturi meter disposed in the conduit and having a cross-section in the plane that is perpendicular to fluid flow, wherein the area of the cross-section gradually decreases and then gradually increases, the venturi meter also having first and second static pressure ports, the first port being located at a relatively wide portion of the venturi meter, and the second port being located at a narrower portion of the venturi meter;
• an adjustable valve for variably impeding flow through the conduit;
• means for measuring the static pressure at first and second ports and adjusting the valve based on the static pressure measured at the first and second static pressure ports;
• and
• a movably mounted piston having frontal and distal faces, the distal face being exposed to a reference pressure an the frontal face being exposed to the flow in the conduit, the piston being so mounted so as to variably restrict flow through the conduit, wherein exerted on the piston are fluid pressures on the piston's frontal and distal faces and a restoring force that tends to lessen the amount the piston restricts flow through the conduit,
• wherein the adjustable valve is mounted upstream of and adjacent to the piston, and
• wherein the frontal face of the piston has a central area and a perimeter, and the adjustable valve is a modulator that redirects flow so that fluid flows across the frontal face of the piston away from the central area radially outward towards the piston's perimeter.

A device for controlling flow through a conduit, the device comprising:

• a venturi meter disposed in the conduit and having a cross-sectional area that decreases and then increases, the venturi meter also having first and second static pressure ports, the first port being located at a relatively wide portion of the venturi meter, and the second port being located at a narrower portion of the venturi meter;
• an adjustable valve for variably impeding flow through the conduit;
• a movably mounted piston mounted downstream from the valve and having frontal and distal faces, the distal face being exposed to a pressure of the flow upstream of the piston and the frontal face being exposed to the flow in the conduit, the piston being so mounted so as to variably restrict flow through the conduit, wherein exerted on the piston are fluid pressures on the piston's frontal and distal faces and a restoring force that tends to lessen the amount the piston restricts flow through the conduit;
• and
• means for measuring the static pressure at first and second ports and adjusting the valve based on the static pressure measured at the first and second static pressure ports;
• wherein the venturi meter and the valve are disposed in the conduit such that substantially all of the flow that passes through the valve also passes through the venturi meter.

A device for controlling flow through a conduit, the device comprising:

• a venturi meter disposed in the conduit and having a cross-sectional area that decreases and then increases, the venturi meter also having first and second static pressure ports, the first port being located at a relatively wide portion of the venturi meter, and the second port being located at a narrower portion of the venturi meter;
• an adjustable valve for variably impeding flow through the conduit;
• a movably mounted piston mounted just downstream from the valve and having frontal and distal faces, the distal face being exposed to a reference pressure and the frontal face being exposed to the flow in the conduit, the piston being so mounted so as to variably restrict flow through the conduit, wherein exerted on the piston are fluid pressures on the piston's frontal and distal faces and a restoring force that tends to lessen the amount the piston restricts flow through the conduit;
• and
• means for measuring the static pressure at first and second ports and adjusting the valve based on the static pressure measured at the first and second static pressure ports;
• wherein the frontal face of the piston has a central area and a perimeter, and the adjustable valve is a modulator that redirects flow so that fluid flows across the frontal face of the piston away from the central area radially outward towards the piston's perimeter.

A device for controlling flow through a conduit, the device comprising:

• a piston having a frontal face exposed to the fluid in the path, the frontal face of the piston forming part of a venturi disposed in the conduit such that the conduit has a cross-sectional area that decreases and then increases, the piston being movably mounted so that the piston may move in a direction tranverse to the flow so as to narrow or widen the venturi;
• first and second static pressure ports, the first port being located at a relatively wide portion of the conduit, and the second port being located at a narrower portion of the conduit;
• position measurement means for determining the position of the piston;
• pressure measurement means for measuring the static pressure at first and second ports;
• displacement means for adjusting the position of the piston;
• and
• control means, in communication with the pressure measurement means, the position measurement means and the displacement means, for controlling the displacement means so as to position the piston based on the static pressure measured at the first and second static pressure ports.