Patent Description:
High pressure fuel systems are used in a variety of applications to provide fuel flow and pressure sufficient to operate gas turbine engines. This can include providing high pressure fuel to actuators that operate to control a variable area engine nozzle portion of the engine.

Fuel systems also may be designed to provide excess fuel capacity, e.g., to assist main fuel pumps, to meet fuel demands during operation conditions. If fuel is supplied from such systems too rapidly, a rich mixture may cause a surge. The documents <CIT> and <CIT> disclose each an adjustable axial piston pump with a swash plate which inclination is to be varied by a control piston.

Disclosed is a direct metering control variable displacement piston <NUM>. pump as defined by the accompanying claims, including: a pump housing defining a housing cavity, a pivot assembly configured to pivot within the pump housing between minimal and maximum pivot angles; a pump cover disposed against the pump housing, the pump cover defining an actuator bore, an actuator piston in the actuator bore, an actuator arm extending from the actuator piston to the pivot assembly; and an electronic control unit (ECU) operationally coupled to the pump, the ECU including: a pump controller, a linear variable differential transducer (LVDT) operationally coupled to the pump controller and the actuator piston, and an electrohydraulic solenoid valve (EHSV) operationally coupled to the pump controller, wherein the ECU is configured to: determine a pivot differential for the pivot assembly between a target pivot angle and a current pivot angle; determine a position differential for the actuator piston, corresponding to the pivot differential of the pivot assembly; control the EHSV to thereby move the actuator piston by the position differential; and determine, from the LVDT, that the actuator piston moved by the position differential.

The ECU is further configured to: monitor to identify pressure perturbations in the pump resulting from pressure changes to a fluid flow; and react to pressure perturbations in the pump with controlled metered movement of the actuator piston.

In addition to one or more aspects of the pump, or as an alternate: the pump cover further includes: an inlet port and an inlet passage that extends from the inlet port to the pump housing; an outlet port and an outlet passage that extends from the outlet port to the EHSV and to the pump housing; a return passage that extends from the EHSV to the pump housing; and a coupling passage that extends between the actuator bore and the EHSV.

In addition to one or more aspects of the pump, or as an alternate, the pump further includes: sensors operationally connected to the ECU, the sensors including: an inlet pressure sensor, disposed in the return passage, configured to sense pump inlet pressure; and an outlet pressure sensor, disposed in the outlet passage, configured to sense pump outlet pressure, wherein the ECU is configured to monitor to identify pressure perturbations in the pump resulting from pressure changes to the fluid flow by sensed pressure fluctuations at the inlet and outlet during movement of the pivot assembly.

In addition to one or more aspects of the pump, or as an alternate, the actuator bore defines a top end and a bottom end, wherein the bottom end is disposed against the pump housing, and the pump further includes: a biasing member configured to bias the pivot assembly toward a maximum pivot angle; an actuator pressure sensor, disposed in the coupling passage, configured to sense pressure at the actuator piston, wherein the ECU is configured to control the EHSV by: increasing pressure against the actuator piston to move the actuator piston toward the bottom end of the actuator bore, countering a biasing force that biases the pivot assembly toward the maximum pivot angle; or reducing pressure against the actuator piston, thereby enabling the biasing force to move the pivot assembly toward the maximum pivot angle, and thereby moving the actuator piston toward the bottom end of the actuator bore.

In addition to one or more aspects of the pump, or as an alternate, the pump is configured so that: when the actuator piston is disposed at the top end of the actuator bore, the pivot assembly is disposed at the maximum pivot angle; and when the actuator piston is disposed at the bottom end of the actuator bore, the pivot assembly is disposed at a minimum pivot angle.

In addition to one or more aspects of the pump, or as an alternate, the pump further includes: a pivot base defining a pivot base cavity, and a coupler shaft seated in the pivot base cavity, the coupler shaft defines piston seats and a coupler shaft bore; a cylinder barrel configured to slide within the pivot assembly, the cylinder barrel defines piston bores and a universal shaft bore; and pistons that extend from the piston seats in the coupler shaft into the piston bores in the cylinder barrel, and a universal shaft that extends from the coupler shaft bore in the coupler shaft to the universal shaft bore in the cylinder barrel.

In addition to one or more aspects of the pump, or as an alternate, the pump is a bent axis pump.

Further disclosed is a gas turbine engine, including: a fuel supply; a pump having one or more of the above disclosed aspects; an engine pressure regulator configured to receive fuel from the pump; and an engine controller operationally coupled to the ECU and configured to communicate parameters to the ECU indicative of the target pivot angle for the pivot assembly.

In addition to one or more aspects of the engine, or as an alternate, the pressure regulator is configured to direct a pressure controlled fuel flow to the engine.

Further disclosed is a method of controlling a variable displacement piston pump, the method including a: determining, via a pump electronic control unit (ECU) that is operationally coupled to the pump, a pivot differential for a pivot assembly of the pump between a target pivot angle and a current pivot angle; determining, by the ECU, a position differential for an actuator piston of the pump, corresponding to the pivot differential for the pivot assembly; controlling an electrohydraulic solenoid valve (EHSV) of the ECU, to thereby move the actuator piston by the position differential; and determine, by a linear variable differential transducer (LVDT) of the ECU, that the actuator piston moved by the position differential.

The method further includes monitoring to identify pressure perturbations in the pump resulting from pressure changes to a fluid flow; and reacting to pressure perturbations in the pump with controlled, metered movement of the actuator piston.

In addition to one or more aspects of the method, or as an alternate, the method further includes: sensing pump inlet pressure via an inlet pressure sensor operationally coupled to the ECU and located in a return passage that is fluidly coupled to the EHSV; sensing pump outlet pressure via an outlet pressure sensor operationally coupled to the ECU and located in an outlet passage of the pump; monitoring to identify pressure perturbations in the pump resulting from pressure changes to the fluid flow by sensed pressure fluctuations at the inlet and outlet during movement of the pivot assembly.

In addition to one or more aspects of the method, or as an alternate, the method further includes sensing pressure at an actuator bore via an actuator pressure sensor operationally coupled to the ECU and located in a coupling passage between the actuator bore and the EHSV, and wherein controlling the EHSV includes: increasing pressure against the actuator piston to move the actuator piston toward a bottom end of the actuator bore, countering a biasing force that biases the pivot assembly toward a maximum pivot angle; or reducing pressure against the actuator piston, thereby enabling the biasing force to move the pivot assembly toward the maximum pivot angle, and thereby moving the actuator piston toward the bottom end of the actuator bore; and determining a pressure required to move the actuator piston toward the bottom end of the actuator bore as a difference between and pressure in the actuator bore.

In addition to one or more aspects of the method, or as an alternate, the method further includes the ECU causing movement of the actuator piston between: a top end of the actuator bore to position the pivot assembly at the maximum pivot angle; and the bottom end of the actuator bore to position the pivot assembly at a minimum pivot angle.

In addition to one or more aspects of the method, or as an alternate, the method further includes: the ECU receiving a communication from an engine controller of a gas turbine engine with parameters indicative of the target pivot angle for the pivot assembly.

Aspects of the disclosed embodiments will now be addressed with reference to the figures. Aspects in any one figure is equally applicable to any other figure unless otherwise indicated. Aspects illustrated in the figures are for purposes of supporting the disclosure and are not in any way intended on limiting the scope of the disclosed embodiments. Any sequence of numbering in the figures is for reference purposes only.

Turning to <FIG>, disclosed is an engine <NUM> that includes a direct metering control variable displacement piston pump <NUM> (for simplicity, a pump <NUM>). While shown in an engine, it shall be understood that embodiments herein can be applied to pump that are not part of an engine as well.

In one embodiment, the pump <NUM> can be any type of pump including a bent axis pump or a vane pump. The pump <NUM> may be installed in an aircraft system such as a gas turbine engine <NUM> having, for example, a full authority digital engine control (FADEC) <NUM> and component <NUM> of FMU and EEC that are operationally coupled to the pump <NUM> via communication lines 120A. The FADEC <NUM> is a system consisting of a digital computer that is called an electronic engine controller (EEC) or engine control unit (EEU), and its related accessories that control all aspects of aircraft engine performance.

In the engine <NUM>, the pump <NUM> may be a high pressure (HP) pump, an actuator pump or a main fuel pump (MFP). An engine component, which may be a fuel pressure regulator otherwise referred to as a fuel manager unit (or FMU and EEC <NUM>), may be configured to receive fuel from a fuel supply <NUM> via the pump <NUM> though passage 120C. Outlet of the FMU and EEC <NUM> may be a pressure-controlled fuel flow <NUM>, which may be directed to the engine <NUM>. The FMU and EEC <NUM> may be operationally coupled to the FADEC via a communication path 120B. The FMU and EEC <NUM> may be fluidly coupled to the pump via passage 120D, which may be utilized as a bypass return to the pump inlet. The FADEC <NUM> may receive input from a pilot-controlled system <NUM>, such as an instrument Computer-Aided-Diagnosis (CAD) panel, that is indicative of a need for an increase or decrease in thrust and vector control. From this, the FADEC <NUM> would send instructions to component <NUM> via the communication lines 120A to the pump <NUM> to change its internal configuration as discussed in greater detail below.

Turning to <FIG>, the pump <NUM> includes a pump housing <NUM>. The pump housing <NUM> defines a housing cavity <NUM>. A pivot assembly <NUM> (or pivot upper housing) is configured to pivot (or swing) within the pump housing <NUM> to an optimized pivot (or tilting or swing) angle <NUM>. The pivot tilting angle <NUM> is measured relative to a drive shaft axis <NUM> of a drive shaft <NUM> having a drive shaft gearbox end <NUM>, and ranges between minimal (along the drive shaft) and maximum (offset from the drive shaft) pivot tilting angles <NUM> to <NUM>. A biasing member <NUM> is configured to bias the pivot assembly <NUM> toward the maximum pivot angle <NUM>, to prevent a circumstance in which the pivot assembly <NUM> is locked at the minimum pivot angle <NUM>. A plate retainer <NUM> prevents pivot assembly <NUM> tilting rotation in the direction that is stopped at minimum tilting angle <NUM>.

The pivot assembly <NUM> includes a pivot arm <NUM> that is supported to pivot at a pivot base <NUM> defines a base cavity <NUM>. A coupler shaft <NUM> is seated in the pivot base cavity <NUM>. The coupler shaft <NUM> has a piston flange <NUM> that defines a piston retainer <NUM> and a coupler shaft bore <NUM>. The coupler shaft <NUM> is operationally connected to the drive shaft <NUM>. A cylinder barrel <NUM> is configured to slide within the pivot assembly <NUM> and defines piston bores <NUM>.

Pistons <NUM> extend from the piston retainer <NUM> in the coupler shaft <NUM> into the piston bores <NUM> in the cylinder barrel <NUM>. A port plate <NUM> may be disposed at the cylinder head (or upper end). A universal shaft (or link) <NUM> extends from the coupler shaft bore <NUM> in the coupler shaft <NUM> to the cylinder barrel <NUM>. According to embodiments, there may be an odd number of pistons <NUM>, such as seven, nine, or eleven pistons, disposed in the cylinder barrel <NUM>. The pistons <NUM> may be configured to reciprocate moving to either a suction or discharge function within the cylinder barrel <NUM>. A cylinder cover <NUM>, at a top end of the pivot assembly <NUM>, includes a bottom portion of a slip guide 346A, which is a track member that prevent the pivot assembly <NUM> from spinning by rotation of the drive shaft <NUM>.

A pump cover <NUM> (or rear cover) is disposed against the pump housing <NUM>. The pump cover <NUM> includes the top portion of the slipper guide 356B to operationally couple with the bottom portion of the slipper guide 346A. The pump cover <NUM> defines an actuator bore <NUM>. An actuator piston <NUM> is disposed in the actuator bore <NUM>. An actuator arm <NUM> (or rod) extends from the actuator piston <NUM> to the pivot assembly <NUM>. The actuator bore <NUM> defines a top end 360A and a bottom end 360B. The bottom end 360B of the actuator bore <NUM> is disposed against the pump housing <NUM>. The pump <NUM> is configured so that when the actuator piston <NUM> is disposed at the top end 360A of the actuator bore <NUM>, the pivot assembly <NUM> is disposed at the maximum pivot angle <NUM>. When the actuator piston <NUM> is disposed at the bottom end 360B of the actuator bore <NUM>, the pivot assembly <NUM> is disposed at the minimum pivot angle <NUM>. In one embodiment, the pump cover <NUM> or ECU <NUM> may be magnetically coupled to the pump housing <NUM>.

As shown in <FIG> and <FIG>, according to an embodiment, an electronic control unit (ECU) <NUM> is operationally coupled to the pump <NUM> and may be within the cover <NUM>. The ECU <NUM> includes a pump controller <NUM> for controlling the pump <NUM> in a direct metering technique. The ECU <NUM> includes a linear variable differential transducer (LVDT) <NUM> that is operationally coupled to the controller <NUM> and the actuator piston <NUM>. The ECU <NUM> also includes an electrohydraulic solenoid valve (EHSV) <NUM> with a supply port 420A, a control (or actuation) port 420B and a return port 420C. The EHSV <NUM> is operationally coupled to the controller <NUM>. The ECU <NUM> may be operationally connected to the FADEC <NUM>, e.g., via the communication lines 120A through component <NUM> by 120B.

The pump cover <NUM> includes an inlet port <NUM> and an inlet passage <NUM> that extends from the inlet port <NUM> to the pump housing <NUM>. The pump cover <NUM> also includes an outlet port <NUM> and an outlet passage <NUM> that extends from the outlet port <NUM> to the pump housing <NUM>. A branch of the outlet passage forms a supply passage <NUM> for the EHSV <NUM>. The pump cover <NUM> further includes a return passage <NUM> that extends from the EHSV <NUM> to the pump housing <NUM>. A coupling passage <NUM> extends between the actuator bore and the EHSV <NUM>.

According to an embodiment, sensors <NUM> are operationally connected to the ECU <NUM>. The sensors <NUM> include an inlet (or return passage) pressure sensor 500A disposed in the return passage <NUM>. The inlet sensor 500A is configured to sense pump inlet pressure. An outlet (or discharge) pressure sensor 500B is disposed in the outlet passage <NUM>. The outlet sensor 500B is configured to sense pump outlet pressure. An actuator (or charge passage) pressure sensor 500C is disposed in the coupling passage <NUM>. The actuator pressure sensor 500C is configured to sense pressure at the actuator piston <NUM>, and more specifically on a top end 370A of the actuator piston <NUM>. Also shown in <FIG> is a schematic representation the spring force 220A from the biasing members <NUM> that the actuator piston <NUM> must overcome to move the pivot assembly <NUM> toward the minimum pivot angle <NUM>.

Turning to <FIG>, a flowchart shows a method of direct metering and controlling the pump <NUM>. As shown in block <NUM>, the method may include determining, via the ECU <NUM>, a pivot differential for the pivot assembly <NUM> through LVDT <NUM> to meet a target pivot angle for it. For example, in an aircraft engine system such as a gas turbine engine <NUM>, the ECU <NUM> may receive a communication from the FADEC <NUM> with parameters indicative of a target pivot angle for the pivot assembly <NUM>, e.g., in order to achieve a desired output change in thrust and vector control. The pivot differential of the pivot assembly <NUM> can be determined as a difference between the current pivot angle and the target pivot angle for the pivot assembly <NUM>. As can be appreciated, a magnitude of the pivot differential may be positive or negative (e.g., representing bidirectional movement in the actuator bore <NUM>), depending on whether the output pressure is required to be increased or reduced.

As shown in block <NUM>, the method may include determining, by the ECU <NUM>, a position differential for the actuator piston <NUM>, corresponding to the pivot differential for the pivot assembly <NUM>. The position differential would be, e.g., moving the actuator piston <NUM> toward the bottom end 360B of the actuator bore <NUM> to decrease the pivot angle and thus the output pressure, or moving the actuator piston <NUM> toward the top end 360A of the actuator bore <NUM> to increase the pivot angle and thus the output pressure. As can be appreciated when the actuator piston <NUM> is at the top end 360A of the actuator bore <NUM>, the pivot assembly <NUM> is positioned at the maximum pivot angle <NUM>. When the actuator piston <NUM> is at the bottom end 360B of the actuator bore <NUM>, the pivot assembly <NUM> is at the minimum pivot angle <NUM>.

As shown in block <NUM>, the method may include controlling the EHSV <NUM> to control flow into or out of the actuator bore <NUM>, and thereby move the pivot assembly <NUM> to the targeted pivot angle, e.g., at or between the minimum and maximum angles <NUM> to <NUM> within a stroke rate to meet dynamic response rise time and slew rate requirement. For example, in aircraft STOVL transient condition, if the target pivot angle is shallower than the current angle, the EHSV <NUM> would direct flow from the pump outlet passage <NUM>, via the EHSV supply passage <NUM>, to the coupling passage <NUM>, and into the actuator bore <NUM>. This direct metering control would increase pressure rapidly against the actuator piston <NUM> until the pressure overcomes the biasing force 220A from the biasing member <NUM>. As a result, the actuator piston <NUM> would move quickly within expected stroke rate toward the bottom end 360B of the actuator bore <NUM>, and the pivot angle of the pivot assembly <NUM> would be reduced, which would decrease output pressure.

On the other hand, if the target pivot angle is greater than the current angle, the EHSV <NUM> would direct flow from the coupling passage <NUM> to the EHSV return passage <NUM>. This would reduce the pressure against the actuator piston <NUM> to enable the biasing forces 220A from the biasing member <NUM> to cause the actuator piston <NUM> to move toward the top end 360A of the actuator bore <NUM>. As a result, the pivot angle of the pivot assembly <NUM> would increase, which would increase output pressure.

With the disclosed embodiments, the actuator pressure sensor 500C can be utilized to sense pressure at the actuator bore <NUM>, and therefore utilized to control the EHSV <NUM>. A pressure required to move the actuator piston <NUM> toward the bottom end 360B of the actuator bore <NUM> would be greater than both the current pressure in the bore <NUM> and the biasing force 220A from the biasing member <NUM>. On the other hand, pressure required to move to move the actuator piston <NUM> toward the top end 360A of the actuator bore <NUM> would be less than the current pressure in the actuator bore <NUM>, e.g., between the top end 360A of the bore and the top end 370A of the actuator piston <NUM>.

As shown in block <NUM>, the method includes determining, by the LVDT <NUM>, that the actuator piston <NUM> moved transposition and stroke rate by the position differential. As shown in block <NUM>, during movement of the actuator piston <NUM>, the process includes monitoring feedback from the pressure sensors 500A, 500B to identify pressure perturbations in the pump <NUM>, e.g., based on the pressure rise between the pump input and output, resulting from pressure changes to the fluid flow. As shown in block <NUM>, the method includes reacting to pressure perturbations in the pump <NUM> with controlled, metered movement of the actuator piston <NUM>, thus controlled, metering movement of the pivot assembly <NUM>. This feedback loop enables direct metering control of the actuator piston <NUM>, and thus the pivot assembly <NUM>, to reduce the potential of damaging reactions to flow changes in the pump <NUM>.

The above embodiments enable a steady and metered motion of the pivot assembly <NUM> by providing steady and metered motion of the actuator piston <NUM> in the actuator bore <NUM>. Metered control occurs by the EHSV <NUM> providing a controlled flow of the fluid into and out of the actuator bore <NUM>, and the LVDT <NUM> providing feedback as to the position of the actuator piston <NUM> in the actuator bore <NUM>. Thus, the ECU <NUM> minimizes pressure waves (e.g., ripple energy) in the hydraulic system by providing a rapid response to such waves via metered control of the actuator piston <NUM>.

The FMU and EEC <NUM> contains pressure sensor for sensing required forces for actuating an engine thrust vectoring control, and flow meter for measuring the engine thrust burning flow prerequisite. The pressure sensor of the FMU and EEC <NUM> detects the system required pressure and provides feedback to the digital control <NUM> and EHSV <NUM> to adjust the titling angle <NUM> of the pivot assembly <NUM> through the LVDT <NUM>, which measures the stroke of the actuator piston <NUM> to determine proper delivery flow rate and responsively modulates the system pressure changes.

With the disclosed embodiments, the metered control actuator piston <NUM> can prevent the actuator piston <NUM>, and thus the pivot assembly <NUM>, from moving too quickly or slowly to a targeted position, or from moving too far or not far enough. The metered control of the actuator piston <NUM> can also rapidly account for fluctuations in fluid pressure by enabling a rapid response by it.

Benefits of the embodiments include a relatively quick and accurate direct metering control of the actuator piston <NUM>, and therefore the pivot assembly <NUM> of the pump <NUM>, to thereby provide a target flow rate and pressure rise. The embodiments provide a stable, fast, and precise control of the pivot angle of the pivot assembly <NUM> to reduce the likelihood of a hydraulic system pressure spike. The embodiments provide an increasing mean time before failure (MTBF) by lowering the pressure ripple to reduce the structure stress fluctuation for the fatigue life and improve reliability. Further, the embodiments utilize the EHSV <NUM> and LVDT <NUM> instead of, for example, a more complex conventional hydraulic compensator, to provide for a relatively light weight pump <NUM> having a relatively simplified flow path configuration in the pump cover <NUM>.

As described above, embodiments can be in the form of processor-implemented processes and devices for practicing those processes, such as a processor utilized in Unmanned Aerial Vehicle (UAV).

Claim 1:
A direct metering control variable displacement piston pump, comprising:
a pump housing (<NUM>) defining a housing cavity, a pivot assembly configured to pivot within the pump housing (<NUM>) between minimal and maximum pivot angles;
a pump cover (<NUM>) disposed against the pump housing (<NUM>), the pump cover (<NUM>) defining an actuator bore, an actuator piston in the actuator bore, an actuator arm extending from the actuator piston to the pivot assembly; and
an electronic control unit "ECU" (<NUM>) operationally coupled to the pump, the ECU comprising: a pump controller, a linear variable differential transducer "LVDT" operationally coupled to the pump controller and the actuator piston, and an electrohydraulic solenoid valve "EHSV" operationally coupled to the pump controller,
wherein the ECU is configured to:
determine a pivot differential for the pivot assembly between a target pivot angle and a current pivot angle;
determine a position differential for the actuator piston, corresponding to the pivot differential of the pivot assembly;
control the EHSV to thereby move the actuator piston by the position differential; and
determine, from the LVDT, that the actuator piston moved by the position differential; and characterized by
monitoring to identify pressure perturbations in the pump resulting from pressure changes to a fluid flow; and
reacting to pressure perturbations in the pump with controlled metered movement of the actuator piston.