| CPC F16K 31/406 (2013.01) [F02C 7/232 (2013.01); F02C 9/263 (2013.01); F02C 9/32 (2013.01)] | 20 Claims |

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1. A metering valve, comprising:
a valve body having an inner surface that defines a valve chamber, the valve body further including at least a fluid inlet port, a fluid outlet port, a metering valve control pressure inlet port, a servo control pressure inlet port, and a servo control pressure outlet port, the metering valve control pressure inlet port in fluid communication with the servo control pressure inlet port;
a valve element movably disposed within the valve chamber and defining therein at least a control pressure chamber and a return pressure chamber, the valve element responsive to fluid pressure in the control pressure chamber to move between a closed position, in which the fluid inlet port is fluidly isolated from the fluid outlet port to prevent fluid flow from the fluid inlet port to the fluid outlet port, and a plurality of open positions, in which the fluid inlet port is in fluid communication with the fluid outlet port to allow fluid flow from the fluid inlet port to the fluid outlet port;
a rotary servo rotationally disposed within the return pressure chamber, the rotary servo rotatable about a rotational axis to a plurality of servo positions to thereby vary fluid pressure in the control pressure chamber, whereby the valve element is moved between the closed position and the plurality of open positions; and
a stepper motor coupled to the rotary servo, the stepper motor responsive to commands to rotate the rotary servo to a commanded servo position, whereby the valve element is moved to a commanded valve element position.
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