Fluid control system

• US 3,995,800 A
• Filed: 06/18/1975
• Issued: 12/07/1976
• Est. Priority Date: 08/24/1973
• Status: Expired due to Term

• Current Assignee: LTV Aerospace and Defense Company
• Original Assignee: Vought Corp.
• Inventors: Swogger, Emery C.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Barefoot, Galen L.
• Application Number:
  US05/588,127
• Time in Patent Office: 538 Days
• Field of Search: 244/78, 91/33, 91/31, 91/363 A, 91/445, 91/411 A
• US Class Current: 244/78.2
• CPC Class Codes: B64C 13/38 with power amplification
• CPC Class Codes: B64C 13/42 having duplication or stand-by provisions

Abstract

A fluid-powered control system of a type employing redundant control channels and multiple fluid signal amplifiers. Each fluid amplifier has two fluid outlets having communication with respective portions of a movable, force summing structure but having no communication with the other amplifiers. A respective, differential pressure monitoring device is connected between a source of fluid under pressure and each fluid amplifier and is operative to shut off fluid flow to the respective, associated, fluid amplifier upon the occurrence, across the outlets of the fluid amplifier, of a differential pressure exceeding a predetermined level.

Claims

1. An aircraft servo control system responsive to a plurality of redundant electrical command signals and operative to position a movable airfoil, the control system comprising:

a plurality of electro hydraulic transducers each responsive to a respective one of the electrical command signals and each operative to produce a differential pressure fluid output signal corresponding to the respective electrical command signal;

means summing the outputs of the electro hydraulic transducers by means of a movable piston structure having a respective pair of piston faces corresponding to each pair of transducer outlets whereby the position of the piston structure corresponds to the net electrical command signal applied to the transducers;

means monitoring the differential pressure across the fluid outlets of each transducer and shutting off any transducer upon the differential pressure across its outlets exceeding a predetermined amount;

fluid powered actuator means operable to translate the airfoil and having a movable piston structure operatively connected to the airfoil;

force amplifying means comprising a flow control valve having a valve element to which the movable piston structure is operatively connected, the flow control valve having fluid outlets connected to drive the actuator;

the force amplifying means and the summing means comprising a means controlling the velocity of movement of the actuator piston structure; and

position feedback means connected between the actuator and the respective transducers for generating a position correction signal for each transducer.

2. An aircraft servo control system responsive to a plurality of redundant electrical command signals and operative to position a movable airfoil, the control system comprising:

a plurality of electrohydraulic transducer each responsive to a respective one of the electrical command signals and each having two fluid outlets and being operative to produce a differential pressure fluid output signal corresponding to the respective electrical command signal;

means summing the outputs of the electrohydraulic transducers by means of a movable piston structure having a respective pair of piston faces corresponding to each pair of transducer outlets whereby the position of the piston structure corresponds to the net electrical command signal applied to the transducers;

means monitoring the differential pressure across the fluid outlets of each transducer and shutting off any transducer upon the differential pressure across its outlets exceeding a predetermined amount;

fluid powered actuator means operable to translate the airfoil and having a movable piston structure operatively connected to the airfoil;

force amplifying means comprising a flow control valve having a valve element to which the movable piston structure of the means summing the outputs of the electrohydraulic transducers is operatively connected, the flow control valve having fluid outlets connected to drive the actuator;

the force amplifying means and the summing means comprising a means controlling the velocity of movement of the actuator piston structure; and

position feedback means connected between the actuator and the respective transducers for generating a position correction signal for each transducer.

3. The apparatus of claim 2, the movable piston structure of the means summing the outputs of the electrohydraulic transducers comprising means movable independently of the airfoil and free of mechanical connection with the airfoil.

4. The apparatus of claim 2, including mechanical position feedback means, comprising respective mechanical elements connected between respective ones of the transducers and the piston structure of the summing means, for generating position correction signals for each transducer.

5. The apparatus of claim 2, the means monitoring the differential pressure across the fluid outlets of each transducer comprising, for each respective transducer:

a valve housing having a chamber and having, in communication with the chamber, first, second, and third ports and at least one drain opening, the third and fourth ports having communication with the resepective outlets of the corresponding, associated transducer, the first port communicating with a source of fluid under pressure and the second port communicating with the fluid inlet of the respective transducer;

a valve member slideably mounted within the valve housing chamber and movable therein within first, second, third, fourth, and fifth position ranges, the valve member having a passageway which communicates between the first and second ports upon the valve member being positioned within its third positional range, the valve member having valving means for shutting off fluid flow between the first and second ports upon the valve member being positioned within its first positional range and, alternatively, upon the valve member being positioned within its fifth positional range;

pressure responsive means, responsive to any differential pressure between the first and second fluid outlets of the respective, associated transducer, for constraining the valve member within its third positional range when any difference between the pressure level within the fluid amplifier first outlet and the second outlet below a predetermined amount, for moving the valve member from its third to its second positioned range upon the pressure in the first outlet falling below that in the second outlet by the predetermined amount, and for moving the valve member from its third to its fourth positional range upon the pressure within the second outlet falling below that in the first outlet by the predetermined amount; and

latching means, for moving the valve member from its second to its first positional range upon the valve member entering its second positional range, and for moving the valve member from its fourth to its fifth positional range upon the valve member entering its fourth positional range.

6. The apparatus of claim 5, the pressure responsive means including means for moving the valve member from its first to its third positional range and, alternatively, from its fifth to its third positional range, upon fluid flow into the valve through the first port being shutoff.

7. An aircraft servo control system responsive to a plurality of redundant electrical command signals and operative to position a movable airfoil, the control system comprising:

a source of fluid under pressure;

a plurality of electrohydraulic transducers each responsive to a respective one of the electrical command signals and each operative to produce a differential pressure fluid output signal corresponding to the respective electrical command signal;

means summing the outputs of the electrohydraulic transducers by means of a movable piston structure having a respective pair of piston faces corresponding to each pair of transducer outlets whereby the position of the piston structure corresponds to the net electrical command signal applied to the transducers;

a plurality of means, each fluidly connected in series between the source of fluid under pressure and a respective one of the electrohydraulic transducers, for monitoring the differential pressure across the fluid outlets of each transducer, and for shutting off fluid flow to a respective transducer upon the differential pressure across its outlets exceeding a predetermined amount;

fluid powered actuator means operable to translate the airfoil and having a movable piston structure operatively connected to the airfoil;

force amplifying means comprising a flow control valve having a valve element to which the movable piston structure is operatively connected, the flow control valve having fluid outlets connected to drive the actuator;

the force amplifying means and the summing means comprising a means controlling the velocity of movement of the actuator piston structure; and

position feedback means connected between the actuator and the respective transducers for generating a position correction signal for each transducer.