Fuel system with reduced bypass flow

Abstract

A flow system (10) includes a flow source device (12) configured to receive fluid from a first flow line (14) and output fluid on a second flow line (16). An outlet (18) is in fluid communication with the flow source device on the second flow line. An actuation system (22) is in fluid communication with the second flow line through the third flow line (20). A flow meter (28) measures the flow in the second flow line without diverting any fluid to the first flow line. A controller (26) is in fluid communication with the flow source device and the flow meter. The controller adjusts the flow source device to achieve a desired flow rate at the outlet based on a state of the flow source device and the flow rate measured by the flow meter.

Description

Technical Field

[0001] The present invention relates generally to a fluid flow system, and more particularly to a fluid flow system with reduced bypass flow. Background Art

[0002] Conventional commercial aircraft fuel systems use fixed displacement fuel pumps where the pump speed (and therefore pump flow) is proportional to engine speed. However, depending on the current operating conditions (e.g., acceleration, deceleration, or steady state), the engine may require very different amounts of fuel at the same speed. Likewise, even at maximum metered flow requirements, a pump sized to provide the required flow at a certain speed is typically oversized at other speeds. Excess pump flow is diverted back to the inlet side of the pump. Diverting the flow in this way increases the temperature of the fuel. Hotter fuel is undesirable because it reduces the amount of heat that the fuel can absorb from the fuel / oil heat exchange, thereby reducing engine system efficiency.

[0003] Attempts have been made to provide low bypass flow systems. For example, variable displacement pumps have been used instead of fixed displacement pumps to reduce bypass flow. In such systems, an electronic controller determines the required pump displacement. A linear variable displacement transformer (LVDT) from a flow sensing valve in the metering flow path provides a feedback input to the controller. A variable stator vane actuator piston also provides a feedback input to the controller. Based on these inputs, the controller sends a signal to a two-stage electrohydraulic servo valve (EHSV), which positions a servo valve mechanically associated with the pump. This scheme requires variable bypass flow in excess of system demand to meet dynamic performance requirements (e.g., to accommodate external disturbances and metering flow demand tracking). Although this system provides improved dynamics, this improvement comes at the expense of introducing bypass flow into the metering system.

[0004] In view of the foregoing, applicants have discovered that there is a need in the art for a flow system that provides variable flow depending on operating conditions without the need to divert fuel back to the inlet side of the pump. Summary of the invention

[0005] Embodiments of the present disclosure relate to a flow system having reduced bypass flow while maintaining the responsiveness required to meet dynamic performance requirements. These and other advantages of the disclosed flow system, as well as additional inventive features, will be apparent from the description of embodiments of the flow system provided herein.

[0006] According to one approach, an embodiment of the present disclosure relates to a flow system. The flow system includes a flow source device configured to receive a fluid from a first flow line at a first energy and output a fluid on a second flow line at a second energy. The second energy is different from the first energy. A first outlet is in fluid communication with the flow source device on the second flow line. A first actuation system is in fluid communication with the second flow line through a third flow line, and the first actuation system has an outlet in fluid communication with the first flow line. An actuator is coupled to the flow source device, and the actuator is configured to adjust the second energy of the flow source device. A first flow meter is arranged on the second flow line, and the first flow meter is configured to measure a first flow in the second flow line without diverting any fluid to the first flow line. A controller communicates with the flow source device, the first flow meter, and the actuator. The controller is configured to actuate the actuator to adjust the flow source device so as to achieve a desired flow at the first outlet based at least in part on the state of the flow source device and the first flow measured by the first flow meter.

[0007] In one or more embodiments, the first actuation system includes at least one servo actuator. The controller is in communication with the at least one servo actuator, and the controller calculates an estimated flow through the at least one servo actuator based on an actuation position of the servo actuator. The controller is configured to actuate the actuator to adjust the flow source device so as to achieve a desired flow at the first outlet based at least in part on the estimated flow.

[0008] In one or more embodiments, the flow system further comprises a second flow meter disposed on the third flow line. The second flow meter is configured to measure a second flow rate in the third flow line without diverting any fluid to the first flow line. The controller is configured to actuate the actuator to adjust the flow source device so as to achieve a desired flow rate at the first outlet also based at least in part on the second flow rate measured by the second flow meter.

[0009] In one or more such embodiments, the flow system further comprises a second actuation system in fluid communication with the second flow circuit via the third flow circuit. The second flow rate measured by the second flow meter is the total flow rate of the fluid flowing to the first actuation system and the fluid flowing to the second actuation system.

[0010] In one or more other embodiments, the flow system further comprises a second actuation system in fluid communication with the second flow line and a third flow meter configured to measure a third flow rate of the fluid flowing through the second actuation system. The second flow rate measured by the second flow meter belongs only to the fluid flowing through the first actuation system. The controller is configured to actuate the actuator to adjust the second flow rate of the flow source device so as to achieve a desired flow rate at the first outlet also based at least in part on the flow rate measured by the second flow meter and the third flow rate measured by the third flow meter.

[0011] In more than one embodiment, the first flow meter is an ultrasonic flow meter, a Coriolis flow meter, a turbine flow meter, a momentum flow meter, an angular momentum flow meter, an orifice flow meter, a strain gauge flow meter, an optical flow meter, a thermal diffusion flow meter, a volumetric flow meter, an electromagnetic flow meter, a flow sensing valve, a vortex flow meter, an oscillating jet flow meter, and a differential head flow meter.

[0012] In one or more embodiments, the first flow meter has a bandwidth of at least 10 Hz.

[0013] In one or more embodiments, the controller is configured to sample the flow rate measured by the first flow meter every 0.1 seconds or faster.

[0014] In one or more embodiments, the actuator is an electromagnetic actuator.

[0015] In one or more embodiments, the flow system includes a second outlet in fluid communication with the flow source device, and the first flow rate measured by the first flow meter is a total flow rate of the fluid flowing to the first outlet and the second outlet.

[0016] In one or more other embodiments, the flow system includes a second outlet in fluid communication with the flow source device and a second flow meter configured to measure a second flow rate of the fluid flowing to the second outlet. The first flow rate measured by the first flow meter belongs only to the fluid flowing to the first outlet. The controller is configured to actuate the actuator to adjust the flow source device so as to achieve a desired flow rate at the first outlet and the second outlet based at least in part on the first flow rate measured by the first flow meter and the second flow rate measured by the second flow meter.

[0017] In one or more embodiments, the controller comprises an open loop gain margin of at least 6 dB.

[0018] In one or more embodiments, the controller comprises an open loop phase margin of at least 45°.

[0019] In one or more embodiments, the flow source device is a rotary displacement pump, a reciprocating displacement pump, a centrifugal pump, a jet pump, an electromagnetic pump, an accumulator, or a potential energy pump.

[0020] In more than one embodiment, the controller adjusts the flow source device based on the following states of the flow source device: rotational speed, axial speed, rotational position, axial position, inlet pressure, outlet pressure, cam position, swash plate position, displacement, fluid temperature at the inlet of the flow source device and / or fluid temperature at the outlet of the flow source device.

[0021] In one or more embodiments, the first outlet is a fuel manifold of an aircraft, and the first actuation system controls an end effector of the aircraft.

[0022] According to another embodiment, an embodiment of the present disclosure relates to a method for controlling a flow system. In the method, the energy of a fluid flowing to an outlet through a flow source device is changed. The fluid enters the flow source device through a first flow line, and flows out of the flow source device through a second flow line to the outlet. A portion of the fluid on the second flow line is guided through a first actuation system on a third flow route. The first actuation system has an outlet connected to the first flow line fluid. A first flow meter is used to monitor a first flow rate of the fluid flowing through the second flow line. During monitoring, the first flow meter does not divert the fluid from the second flow line to the first flow line. At least partially based on the first flow rate monitored by the first flow meter and the state of the flow source device, the desired flow rate at the outlet is controlled by adjusting the flow source device using an actuator.

[0023] In one or more embodiments, the monitoring further comprises monitoring a second flow rate of the fluid flowing through the third flow line using a second flow meter. During the monitoring period, the second flow meter does not divert the fluid from the third flow line to the first flow line. In addition, the controlling further comprises controlling the desired flow rate based at least in part on the second flow rate monitored by the second flow meter.

[0024] In one or more embodiments, controlling further involves sampling the first flow rate every 0.1 seconds or faster using a controller. In one or more embodiments, controlling further involves sampling the second flow rate every 0.1 seconds or faster using a controller.

[0025] In one or more embodiments, controlling further involves electromagnetically actuating the actuator to adjust the flow source device.

[0026] Other aspects, objects and advantages of the disclosed flow system will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and form a part of this patent specification, illustrate several aspects of the present disclosure and, together with the description, are used to explain the principles of the disclosed flow system. In the drawings:

[0028] Figure 1 is a schematic representation of a flow system according to an exemplary embodiment of the present disclosure;

[0029] Figure 2 including a graph of gain and phase shift as a function of frequency for a flow system using closed loop frequency response analysis according to an exemplary embodiment of the present disclosure;

[0030] Figure 3 including a graph of gain and phase shift as a function of frequency for a flow system using an open loop frequency response analysis according to an exemplary embodiment of the present disclosure;

[0031] Figure 4 is a schematic representation of a flow system having multiple outputs and multiple actuation systems according to an exemplary embodiment of the present disclosure;

[0032] Figure 5 is a schematic representation of a flow system having an actuation system in which flow through the actuation system is estimated based on a position of a servo-actuator within the actuation system according to an exemplary embodiment of the present invention; and

[0033] Figure 6 A graph depicting a flow rate measured when changing from a first desired flow rate to a second desired flow rate according to an exemplary embodiment of the present disclosure.

[0034] Although the flow system will be described in conjunction with certain preferred embodiments, it is not intended to be limited to those embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents included within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION

[0035] Figure 1 An embodiment of a flow system 10 such as a fuel control system (e.g., for an aircraft) is depicted. The flow system 10 includes a flow source device 12 that receives a fluid at a first energy on a first flow line 14, and the flow source device 12 ejects a fluid at a second energy on a second flow line 16. The first energy is different from the second energy. For example and as Figure 1 As shown, the fluid at the first energy is a low-pressure fluid P B , and the fluid in the second energy is a high-pressure fluid P SIn one or more other embodiments, the fluid at the first energy has a flow rate different from the fluid at the second energy. In one or more embodiments, the flow source device 12 is a rotary displacement pump (such as a screw pump, a screw pump, a gear pump, or a vane pump), a reciprocating displacement pump (such as a piston pump, a plunger pump, or a diaphragm pump), a centrifugal pump (such as an axial centrifugal pump, a hybrid centrifugal pump, or a peripheral / regenerative centrifugal pump), a jet pump, an electromagnetic pump, an accumulator, or a potential energy pump.

[0036] In the depicted embodiment, the fluid at the second energy (high pressure fluid P S ) is provided to an outlet 18 through which the fluid is provided to downstream processes, such as a fuel manifold and a combustion chamber (not shown) of an exemplary embodiment of a fuel system. In such an embodiment, the pressure P of the fluid S It may be set by the nozzles of the fuel manifold that inject the fuel into the combustion chamber. In an embodiment, the downstream process may require a fluid with variable energy (eg, pressure or flow), and the flow source device 12 adjusts the energy of the fluid.

[0037] In addition, the fluid at the second energy (depicted as high-pressure fluid P) ejected from the flow source device 12 S ) flows on a third flow line 20 to an actuation system 22 to control a mechanical device. In one or more embodiments, the actuation system 22 includes a servo valve, such as an electrohydraulic servo valve (EHSV). In one or more embodiments, the servo valve is configured to actuate an end effector, such as a flight control surface of an aircraft. The actuation system 22 has a drain port that returns fluid to the input side of the flow source device 12.

[0038] The flow source device 12 is electrically, mechanically, electromechanically or electromagnetically coupled to an actuator 24 controlled by a controller 26. In particular, the controller 26 receives a request for a desired flow rate at the outlet 18, and the controller 26 actuates the actuator 24 to adjust the flow source device 12 to meet the desired flow rate. For example, the flow source device 12 can be a variable displacement vane pump (VDVP), and the actuator 24 can be a linear actuator configured to position a reaction ring within the VDVP to control the flow output in response to a command from the controller 26. In one or more embodiments, the actuator is a linear actuator or a rotary actuator. In one or more embodiments, the actuator is a linear electric actuator or a motor, such as a stepper motor.

[0039] like Figure 1As shown, the first flow meter 28 is positioned on the second flow line 16 to monitor the flow to the outlet 18. According to an embodiment of the present disclosure, the first flow meter 28 monitors the flow to the outlet 18 without diverting any fluid to the input side of the flow source device 12. In one or more embodiments, the first flow meter 28 is an ultrasonic flow meter, a Coriolis flow meter, a turbine (single turbine or twin turbine) flow meter, a momentum flow meter, an angular momentum flow meter, an orifice flow meter, a strain gauge flow meter, an optical flow meter, a thermal diffusion flow meter, a volumetric flow meter, an electromagnetic flow meter, a flow sensing valve, a vortex flow meter, an oscillating jet flow meter, and a differential head flow meter. In one or more embodiments, the first flow meter 28 has a bandwidth of at least 10 Hz, more specifically at least 50 Hz, more specifically at least 75 Hz, and specifically at least 100 Hz. In one or more embodiments, the first flow meter 28 has a bandwidth of up to 500 Hz, more specifically up to 1000 Hz, and specifically up to 2000 Hz. In one or more embodiments, the bandwidth of the first flow meter 28 is selected based on expected transients in flow generated by flow to the actuation system 22. That is, a first flow meter 28 with a relatively high bandwidth may be used in conjunction with an actuation system 22 that generates more frequent transients in flow.

[0040] In one or more embodiments, the flow system 10 further includes a second flow meter 30 on the third flow line 20 to monitor the flow to the actuation system 22. According to an embodiment of the present disclosure, the second flow meter 30 monitors the flow to the actuation system 22 without diverting the fluid to the input side of the flow source device 12. In one or more embodiments, the second flow meter 30 is an ultrasonic flow meter, a Coriolis flow meter, a turbine (single turbine or twin turbine) flow meter, a momentum flow meter, an angular momentum flow meter, an orifice flow meter, a strain gauge flow meter, an optical flow meter, a thermal diffusion flow meter, a volumetric flow meter, an electromagnetic flow meter, a flow sensing valve, a vortex flow meter, an oscillating jet flow meter, and a differential head flow meter. In one or more embodiments, the second flow meter 30 has a bandwidth of at least 10 Hz, more specifically at least 50 Hz, more specifically at least 75 Hz, and specifically at least 100 Hz. In one or more embodiments, the second flow meter 30 has a bandwidth of up to 500 Hz, more specifically up to 1000 Hz, and specifically up to 2000 Hz. As mentioned above with respect to the first flow meter 28 , the bandwidth of the second flow meter 30 may be selected based on the expected transients of the flow rate generated by the flow to the actuation system 22 .

[0041] In one or more embodiments, the flow rates measured by the first flow meter 28 and the second flow meter 30 are transmitted to the controller 26. The state of the flow source device 12 is also transmitted to the controller 26. Depending on the type of flow source device 12 used in the flow system 10, various states of the flow source device 12 can be transmitted to the controller 26. In one or more embodiments, the state of the flow source device 12 is at least one of speed (rotational speed and / or axial speed), position (rotational position and / or axial position), pressure (inlet pressure and / or outlet pressure), displacement (e.g., cam position or swash plate position), or fluid temperature (at the inlet and / or outlet). For example, if the flow source device 12 is a VDVP, the radial velocity of the VDVP is transmitted to the controller 26. In another example, if the flow source device 12 is a valve, the position of the valve is transmitted to the controller 26.

[0042] Therefore, in the control scheme of the flow system 10, the controller 26 receives the instruction input 32 regarding the ideal state of the outlet 18, and measures the flow rate of the second flow line 16 using the first flow meter 28, thereby measuring the current state of the outlet 18, and confirming when the ideal state of the outlet 18 is reached. In addition, since the actuation system 22 is connected to the second flow line 16 via the third flow line 20, the state of the flow to the actuation system 22 is related to achieving the ideal state of the outlet 18, and the flow rate of the third flow line 16 measured by the second flow meter 30 is fed back to the controller 26. In addition, the controller 26 monitors the state of the flow source device 12 based on the flow information from the first flow meter 28 and the second flow meter 30, and adjusts the state of the flow source device 12 using the actuator 24. In this way, despite the potential interference with the flow rate on the second flow line 16 caused by supply fluctuations when the actuation system 20 is actuated, the ideal state of the outlet 18 can still be achieved and maintained.

[0043] In one or more embodiments, the controller 26 samples the flow rate every 0.1 seconds or faster, every 0.05 seconds or faster, every 0.01 seconds or faster, every 0.005 seconds or faster, or every 0.003 seconds or faster. In one or more embodiments, the controller 26 samples the flow rate approximately every 0.002 seconds.

[0044] According to an embodiment of the present disclosure, the structure of the controller 26 is not particularly limited, and can be any of various structures known in the art, for receiving flow information, the state of the flow source device and the required flow, and implementing programming instructions to enable the flow source device 12 to achieve the flow requirements. In one or more embodiments, the controller 26 is a microcontroller (MCU) or a system on a chip (SoC). In one or more embodiments, the controller 26 includes a processor such as a microprocessor and a memory such as a system memory and a program memory, wherein the processor is configured to implement program instructions stored in the memory. In one or more embodiments, the controller 26 is a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0045] Figure 2 and Figure 3 Graphs of the modeled closed-loop frequency response of the flow system 10 and the modeled open-loop frequency response of the flow system 10 are provided. The flow system 10 is modeled for an aircraft fuel system in three states: idle, cruise, and takeoff. Figure 2 and Figure 3 As shown in the graph, the idle condition provides the lower bound for the frequency response, while the takeoff condition provides the upper bound. Based on the frequency of the + / -3% closed loop frequency response, Figure 2 The gain (ratio of modeled flow at the outlet to the required flow) and phase shift are plotted separately. Based on the frequency of the + / -3% open loop frequency response, Figure 3 The gain and phase shift are plotted respectively. Figure 2 As can be seen, a 45° phase shift corresponds to a frequency of 5.6 Hz at idle and 13.1 Hz at takeoff. Compared to conventional systems, the cutoff frequency is in the range of 2 Hz to 3 Hz. Thus, the disclosed flow system has a greater bandwidth for system stability and efficient operation.

[0046] If you can Figure 3 As can be seen, the open-loop phase margin is in the range from 48° to 59°, which is an indication of a stable control system, and the open-loop gain margin is at least 8 dB (i.e., the gain is less than 0.40 at a phase shift of 180°), which is also an indication of a stable control system. In one or more embodiments, the open-loop gain margin is at least 6 dB and / or the open-loop phase margin is at least 45°.

[0047] The embodiments described thus far have discussed a flow system 10 with a single outlet 18 and a single actuation system 22. However, in other embodiments, the flow system 10 includes multiple outlets 18, multiple actuation systems 22, or multiple outlets 18 and actuation systems 22. Figure 4 An embodiment of a flow system 10 having multiple outlets 18 and multiple actuation systems 22 is depicted.

[0048] like Figure 4 As shown, the second flow line 16 carrying the fluid from the flow source device 12 provides the fluid to the plurality of outlets 18-1, 18-2, ..., 18-N. For example, in the flow system 10 as an aircraft, the plurality of outlets 18-1, 18-2, ..., 18-N may correspond to the pilot manifold, the secondary manifold, and the afterburner manifold, among other possibilities. In one or more embodiments, the flow system 10 includes up to ten outlets 18. Figure 4 As shown, in one or more embodiments, each outlet 18-1, 18-2, ..., 18-N includes a flow divider control valve 34-1, 34-2, ..., 34-N configured to adjust the flow rate of fluid delivered to each outlet 18-1, 18-2, ..., 18-N. In addition, in one or more embodiments, the first flow meter 28 can be located on the second flow line 16 upstream of the branch between the outlets 18-1, 18-2, ..., 18-N, so that the measured flow rate is based on the total flow rate of all outlets 18-1, 18-2, ..., 18-N. Figure 4 In one or more other embodiments of the illustrated embodiments, a first flow meter 28-1, 28-2, ..., 28-N is located on each flow line leading to each outlet 18-1, 18-2, ..., 18-N so that the flow to each outlet 18-1, 18-2, ..., 18-N is measured. The flow measured by the first flow meter 28 or the plurality of first flow meters 28-1, 28-2, ..., 28-N is fed back to the controller 26.

[0049] Figure 4 Also shown is a third flow line 20 that carries fluid from the flow source device 12 to a plurality of actuation systems 22-1, 22-2, ..., 22-N. For example, in the flow system 10 as an aircraft, each actuation system 22-1, 22-2, ..., 22-N can be used to control a corresponding end effector of the aircraft, such as a flight control surface. In one or more embodiments, the flow system 10 includes up to ten actuation systems 22. In one or more embodiments, a second flow meter 30 can be located on the third flow line 20 upstream of a branch between the actuation systems 22-1, 22-2, ..., 22-N, so that the flow measured by the second flow meter 30 is based on the total flow of all the actuation systems 22-1, 22-2, ..., 22-N. In the embodiment including Figure 4In one or more other embodiments of the illustrated embodiment, a second flow meter 30-1, 30-2, ... 30-N is located on each flow line leading to each actuation system 22-1, 22-2, ... 22-N. The flow measured by the second flow meter 30 or the plurality of second flow meters 30-1, 30-2, ... 30-N is fed back to the controller 26.

[0050] Figure 5 Another embodiment of the flow system 10 is depicted in which only the outlet 18 has a flow meter (i.e., the first flow meter 28). In one or more embodiments, the actuator system 22 does not include a flow meter. Applicants have discovered that in most aircraft engine systems, only one or two actuator systems 22 have a servo actuator loop that is capable of producing a large servo flow disturbance on the second flow line 16 leading to the outlet 18. In such an embodiment, the flow through the actuator system 22 is estimated based on the position of the actuator 36 within the actuator system 22. Therefore, the position actuator 36 or actuators 36 within the actuator system 22 are fed back to the controller 26 for adjusting the flow source device 12 based on the required flow. Although Figure 5 A single outlet 18 and a single actuation system 22 are depicted, but the flow system 10 can include multiple outlets 18 and multiple actuation systems 22. In addition, in more than one embodiment with multiple actuation systems 22, a second flow meter 30 can be provided consistent with any actuation system 22 having a large flow rate, and the flow rates of the remaining actuation systems can be estimated based on the position of the actuator 36 in the actuation system.

[0051] Figure 6 A diagram showing the variation of the flow rate required by the flow system of an aircraft is depicted. Three operating states are considered: idle, cruise and take-off. Figure 6 As can be seen in the flow diagram, until the first moment T1, the flow rate is at the first flow rate F1. At the first moment T1, the required flow rate increases by 10% to reach the second flow rate F2. The flow system is able to quickly stabilize at the second flow rate F2, which demonstrates the ability of the flow system to dynamically respond to system requirements despite the exclusion of bypass flow from the flow system.

[0052] The flow system according to the present disclosure reduces the amount of bypass flow in the system, thereby reducing the temperature of the fluid in the system. In this way, the flow system operates more efficiently, and the fluid can be used to provide cooling of system components. By replacing various flow sensing valves with flow meters such as ultrasonic flow meters, bypass flow is avoided. In addition, the response time is improved by electronically controlling the actuator that changes the flow of the flow source device. In addition, the controller can sample the flow of the flow meter at a higher rate than before using a traditional flow sensing valve.

[0053] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference in its entirety and were set forth herein.

[0054] The use of the terms "a" (indefinite article "a" or "an") and "the" and similar references in describing the present invention (especially in the following claims) is interpreted to cover the singular and the plural, unless otherwise stated herein or clearly contradicted by the context. The terms "comprising", "having", "including" and "containing" are interpreted as open terms (i.e., meaning "including, but not limited to"), unless otherwise noted. The statement of numerical ranges herein is intended only to be used as a shorthand for individually referring to each individual numerical value falling within the range, unless otherwise stated herein, and each individual numerical value is incorporated into this specification as if it were individually stated herein. All methods described herein can be performed in any suitable order, unless otherwise stated herein or clearly contradicted by the context. Any and all examples provided herein, or the use of exemplary language (e.g., "such as") are intended only to better illustrate the present invention and do not cause limitation on the scope of the present invention, unless otherwise required. No language in the specification should be interpreted as indicating any unclaimed element as necessary for the practice of the present invention.

[0055] Preferred embodiments of the present invention are described herein, including the best modes known to the inventors for carrying out the present invention. Variations of these preferred embodiments may become apparent to those skilled in the art upon reading the foregoing description. The inventors expect that skilled persons will appropriately adopt such variations, and the inventors intend to practice the present invention in a manner different from that specifically described herein. Therefore, as permitted by applicable law, the present invention includes all variations and equivalents of the subject matter recorded in the appended claims. Moreover, the present invention is included in any combination of the above elements in all possible variations, unless otherwise stated herein or clearly contradicted by the context.

Claims

1. A flow system comprising: a flow source device configured to receive fluid from a first flow circuit at a first energy and output fluid on a second flow circuit at a second energy, the second energy being different from the first energy; a first outlet in fluid communication with the flow source device on the second flow line; a first actuation system in fluid communication with the second flow circuit via a third flow circuit, the first actuation system having an outlet in fluid communication with the first flow circuit; an actuator coupled to the flow source device, the actuator configured to adjust the second energy of the flow source device; a first flow meter disposed on the second flow line, the first flow meter being configured to measure a first flow rate in the second flow line without diverting any fluid to the first flow line; a controller in communication with the flow source device, the first flow meter, and the actuator; The controller is configured to actuate the actuator to adjust the flow source device to achieve a desired flow at the first outlet based at least in part on a state of the flow source device and the first flow measured by the first flow meter.

2. A flow system according to claim 1, wherein the first actuation system includes at least one servo actuator, wherein the controller communicates with the at least one servo actuator, wherein the controller calculates an estimated flow through the at least one servo actuator based on an actuation position of the servo actuator, and wherein the controller is configured to actuate the actuator to adjust the flow source device so as to achieve a desired flow at the first outlet based at least in part on the estimated flow.

3. The flow system of claim 1 , further comprising a second flow meter disposed on the third flow line, the second flow meter being configured to measure a second flow rate in the third flow line without diverting any fluid to the first flow line; The controller is configured to actuate the actuator to adjust the flow source device to achieve a desired flow rate at the first outlet based also at least in part on the second flow rate measured by the second flow meter.

4. The flow system of claim 3, further comprising a second actuation system in fluid communication with the second flow circuit via the third flow circuit; The second flow rate measured by the second flow meter is the total flow rate of the fluid flowing to the first actuation system and the fluid flowing to the second actuation system.

5. The flow system of claim 3, further comprising a second actuation system in fluid communication with the second flow circuit and a third flow meter configured to measure a third flow rate of fluid flowing through the second actuation system; wherein the second flow rate measured by the second flow meter belongs only to the fluid flowing through the first actuation system; The controller is configured to actuate the actuator to adjust the second flow rate of the flow source device so as to achieve a desired flow rate at the first outlet based at least in part on the flow rate measured by the second flow meter and the third flow rate measured by the third flow meter.

6. The flow system of claim 1 , wherein the first flow meter is an ultrasonic flow meter, a Coriolis flow meter, a turbine flow meter, a momentum flow meter, an angular momentum flow meter, an orifice flow meter, a strain gauge flow meter, an optical flow meter, a thermal diffusion flow meter, a positive displacement flow meter, an electromagnetic flow meter, a flow sensing valve, a vortex flow meter, an oscillating jet flow meter, and a differential head flow meter.

7. The flow system of claim 1, wherein the first flow meter has a bandwidth of at least 10 Hz.

8. The flow system of claim 1, wherein the controller is configured to sample the flow rate measured by the first flow meter every 0.1 seconds or faster.

9. The flow system of claim 1, wherein the actuator is an electromagnetic actuator.

10. The flow system of claim 1, further comprising a second outlet in fluid communication with the flow source device; The first flow rate measured by the first flow meter is the total flow rate of the fluid flowing to the first outlet and the second outlet.

11. The flow system of claim 1 , further comprising a second outlet in fluid communication with the flow source device and a second flow meter configured to measure a second flow rate of the fluid flowing to the second outlet; wherein the first flow rate measured by the first flow meter belongs only to the fluid flowing to the first outlet; The controller is configured to actuate the actuator to adjust the flow source device to achieve desired flow rates at the first outlet and the second outlet based at least in part on the first flow rate measured by the first flow meter and the second flow rate measured by the second flow meter.

12. The flow system of claim 1, wherein the controller comprises an open loop gain margin of at least 6 dB.

13. The flow system of claim 1, wherein the controller comprises an open loop phase margin of at least 45°.

14. The flow system of claim 1, wherein the flow source device is a rotary displacement pump, a reciprocating displacement pump, a centrifugal pump, a jet pump, an electromagnetic pump, an accumulator, or a potential energy pump.

15. A flow system according to claim 1, wherein the state of the flow source device is at least one of a rotational speed, an axial speed, a rotational position, an axial position, an inlet pressure, an outlet pressure, a cam position, a swash plate position, a displacement, a fluid temperature at the inlet of the flow source device, or a fluid temperature at the outlet of the flow source device.

16. The flow system of claim 1, wherein the first outlet is a fuel manifold of an aircraft, and wherein the first actuation system controls an end effector of the aircraft.

17. A method of controlling a flow system, comprising: changing the energy of a fluid flowing through a flow source device toward an outlet, the fluid entering the flow source device through a first flow path and flowing out of the flow source device through a second flow path toward the outlet; directing a portion of the fluid on the second flow line through a first actuation system on a third flow path, the first actuation system having an outlet in fluid communication with the first flow line; monitoring a first flow rate of fluid flowing through the second flow line using a first flow meter, wherein the first flow meter does not divert fluid from the second flow line to the first flow line during monitoring; A desired flow rate at the outlet is controlled by adjusting the flow source device using an actuator, the control being based at least in part on the first flow rate monitored by the first flow meter and a state of the flow source device.

18. The method of claim 17, wherein the monitoring further comprises: monitoring a second flow rate of the fluid flowing through the third flow line using a second flow meter, wherein the second flow meter does not divert the fluid from the third flow line to the first flow line during the monitoring period; and The control also includes: The desired flow rate is also controlled based at least in part on the second flow rate monitored by the second flow meter.

19. The method of claim 17, wherein controlling further comprises sampling the first flow rate every 0.1 seconds or faster using a controller.

20. The method of claim 17, wherein controlling further comprises electromagnetically actuating the actuator to adjust the flow source device.

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