Claims
- 1. A fuel metering unit for controlling a fuel pump comprising:
a) a servovalve having a torque motor for applying a force, a first nozzle in fluid communication with the fuel pump and a second nozzle in fluid communication with the fuel pump; b) an elongated arm disposed between the first and the second nozzles so as to vary fluid flow through the first and the second nozzles and operatively mounted to the torque motor, such that actuation of the torque motor controls output of the fuel metering unit; and c) a flow meter in fluid communication with an output of the fuel pump and operatively connected to the elongated arm for variably applying a biasing force against the elongated arm in response to the output of the fuel pump so as to schedule fuel flow accurately.
- 2. The fuel metering unit as recited in claim 1, further comprising a LVDT operatively associated with the flow meter for indicating a fuel flow rate output from the fuel pump.
- 3. The fuel metering unit as recited in claim 1, further comprising a LVDT operatively associated with the elongated arm for indicating a fuel flow rate output from the fuel pump.
- 4. The fuel metering unit as recited in claim 1, further comprising a strain gauge operatively associated with the elongated arm for indicating a flow rate through the flow meter.
- 5. The fuel metering unit as recited in claim 1, wherein the flow meter defines a primary inlet and an outlet in fluid communication with an internal chamber and further comprises a valve member slidingly engaged within the internal chamber for varying a flow of fuel through the flow meter.
- 6. The fuel metering unit as recited in claim 5, wherein the flow meter defines a secondary inlet in fluid communication with the internal chamber for receiving a portion of flow passing through the outlet.
- 7. The fuel metering unit as recited in claim 5, wherein the valve member is operatively connected to the elongated arm.
- 8. The fuel metering unit as recited in claim 5, further comprising a spring for biasing the valve member against a flow of fuel output from the fuel pump.
- 9. The fuel metering unit as recited in claim 5, further comprising a LVDT attached to the valve member for indicating a fuel flow rate of the fuel pump.
- 10. A system for indicating an output of a fuel pump comprising:
a) an elongated arm for controlling the output of a pump; b) a motor coupled to a first end of the elongated arm for moving the elongated arm to a desired position; c) a housing defining an internal chamber, a primary inlet for receiving the output of the fuel pump, an outlet in fluid communication with the primary inlet, and a secondary inlet for receiving a scavenged portion of the output as fluid passing through the outlet; and d) a valve member slidingly received within the internal chamber such that the output and the scavenged portion of the fluid exert a force on the valve member, wherein the valve member is coupled to a second end of the elongated arm for transmitting the force to the arm to assist the motor in positioning the elongated arm.
- 11. A system as recited in claim 10, further comprising a spring for coupling the valve member and the second end of the elongated arm.
- 12. A system as recited in claim 10, further comprising a second spring between the valve member and the housing for applying a biasing force to the valve member.
- 13. A system as recited in claim 10, wherein the elongated arm connects to a LVDT for indicating the output of the fuel pump.
- 14. A system as recited in claim 10, wherein the elongated arm connects to a strain gauge for indicating the output of the fuel pump.
- 15. A system as recited in claim 10, further comprising a boost pump in fluid communication with a middle inlet of the housing to provide a reference pressure in the internal chamber.
- 16. 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 vane 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 vane 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 vane pump to assist in maintaining the position of the elongated arm.
- 17. A fuel metering unit as recited in claim 16, further comprising an axial spacer coaxially arranged with respect to the cam ring for eliminating friction on the cam ring.
- 18. A fuel metering unit as recited in claim 16, wherein the first and second nozzles have an orifice for reducing flow therethrough.
- 19. A fuel metering unit as recited in claim 16, further comprising a LVDT coupled to the elongated arm for indicating output of the fuel metering unit.
- 20. A fuel metering unit as recited in claim 16, further comprising a strain gauge coupled to the elongated arm for indicating output of the fuel metering unit.
- 21. A fuel metering unit as recited in claim 16, wherein the flow meter has a valve slidably mounted therein.
- 22. A fuel metering unit as recited in claim 21, wherein the valve is coupled to the elongated by a spring.
- 23. A fuel metering unit as recited in claim 21, further comprising a LVDT coupled to the valve for indicating an output of the fuel metering unit.
- 24. A fuel metering unit as recited in claim 21, further comprising a conduit to scavenge a portion of flow so as to dampen an effect of transient disturbances on movement of the valve.
- 25. A fuel metering unit as recited in claim 16, further comprising a spring for applying a minimum biasing force upon the elongated arm.
- 26. A flow meter for indicating an output of a pump comprising:
a) a housing defining an internal chamber, a primary inlet for receiving the output of the pump, an outlet in fluid communication with the primary inlet, and a secondary inlet for receiving a scavenged portion of the output passing through the outlet; and b) a valve member slidingly received within the internal chamber such that the output of the pump and the scavenged portion each exert a force on the valve member, wherein a first force exerted by the scavenged portion is a downstream reference pressure opposing a second force exerted by the output of the pump.
- 27. A flow meter as recited in claim 26, further comprising a spring for coupling the valve member to an elongated arm.
- 28. A flow meter as recited in claim 26, further comprising a spring between the valve member and the housing for applying a biasing force to the valve member.
- 29. A flow meter as recited in claim 26, further comprising an elongated arm operatively connected to the valve member and a LVDT operatively connected to the elongated arm for indicating the output of the fuel pump.
- 30. A flow meter as recited in claim 26, further comprising a sensor operatively connected to the valve member for indicating the output of the pump.
- 31. A flow meter as recited in claim 26, further comprising a boost pump in fluid communication with a middle inlet of the housing to provide a reference pressure in the internal chamber.
- 32. A flow meter as recited in claim 26, further comprising an elongated arm operatively connected to the valve member and a strain gauge operatively connected to the elongated arm for indicating the output of the pump.
- 33. A fuel metering unit comprising:
a variable displacement vane pump having,
a rotor including a plurality of radially extending vane slots, a cam ring coaxially arranged with respect to the rotor, said cam ring being pivotally movable with respect to the rotor, and a plurality of vane elements slidably-received within the vane slots of the rotor, such that outer tips of the vane elements contact a radially inward surface of the cam ring upon rotation of the rotor; a servovalve having,
a torque motor including an armature having opposite ends that move in opposed lateral directions in response to the torque motor receiving an electrical current, first and second nozzles operatively connected to the variable displacement vane pump such that increased fluid flow through the first nozzle pivots the cam ring of the vane pump in a first direction while increased fluid flow through the second nozzle pivots the cam ring in a second direction, and an elongated flapper extending between the first and the second nozzles for alternately increasing fluid flow through the first and the second nozzles upon lateral movement of a second end of the elongated flapper, said flapper secured at a first end to the armature of the torque motor so that the flapper extends substantially normal to the armature, whereby the second end of the flapper moves laterally upon the torque motor receiving an electrical current; and a flow meter connected to a high pressure outlet of the vane pump and operatively connected to the second end of the elongated flapper for variably applying a lateral force against the second end of the flapper in response to the output of the vane pump.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation-in-part of U.S. patent application Ser. No. 09/506,465 filed Feb. 17, 2000, the disclosure of which is herein incorporated by reference in its entirety.
Divisions (1)
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Number |
Date |
Country |
Parent |
09867359 |
May 2001 |
US |
Child |
10338550 |
Jan 2003 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
09506465 |
Feb 2000 |
US |
Child |
09867359 |
May 2001 |
US |