Patent ID: 6786702
Filing Date: 2004-09-07
Classification: F04C,Y10T

Abstract:
A fuel metering unit comprising:a) a variable displacement pump including: i) a rotor having a plurality of radially extending vane slots; ii) a cam ring coaxially arranged with respect to the rotor and pivotally movable between a maximum stop position and a minimum stop position with respect to the rotor; and iii) a plurality of vanes slideably disposed in the radially extending vane slots for maintaining contact with the cam ring during movement thereof; b) a servovalve including: i) a torque motor having an armature with opposite ends that move in opposed lateral directions in response to the torque motor receiving an electrical current from an electronic engine controller, ii) first and second nozzles operatively connected to an output of the variable displacement pump such that increased fluid flow through the first nozzle causes the cam ring of the variable displacement pump to pivot toward the maximum stop position while increased fluid flow through the second nozzle causes the cam ring to pivot toward minimum stop position, and iii) an elongated arm extending between the first and the second nozzles and mounted to vary fluid flow therethrough, the elongated arm secured at a first end to the armature of the torque motor such that the elongated arm moves in response to the torque motor receiving an electrical current from the electronic engine controller; and c) a flow meter connected to a high pressure outlet of the variable displacement pump and operatively connected to a second end of the elongated arm for variably applying a force against the elongated arm in response to the output of the variable displacement pump to assist in maintaining the position of the elongated arm.