Fuel regulation system

Abstract

This presentation relates to a fuel regulation system (2) for a turbomachine (1), the system (2) comprising: a main pumping device (22); and a transmission device (3) comprising: a mechanical differential (31); an electric motor (32); and an electrical power supply (33). Figure for the abstract: Fig. 3

Description

Title of the invention: Fuel regulation system technical field

[0001] The present exposition relates to the field of aeronautics. More specifically, the present exposition relates to fuel regulation within an aircraft engine. STATE OF THE ART

[0002] An aircraft engine generally includes a control system configured to respond, sometimes strictly, to the fuel supply requirements of the engine's combustion chamber and, possibly, of an afterburner circuit and / or variable engine geometries, regardless of the engine's operating speed.

[0003] The efficiency, safety and service life of the fuel regulation system depend, in particular, on the properties of the pumps which compose it and their drive method.

[0004] Fuel regulation systems employing a volumetric pump, or a centrifugal pump, driven directly, or via transmission devices, by the engine accessory housing, have been proposed, but do not provide complete satisfaction. GENERAL STATEMENT

[0005] One aim of the present presentation is to increase the service life and improve the efficiency, particularly thermal, of a fuel regulation system of a turbomachine, in a simple and inexpensive way, without increasing its mass.

[0006] To this end, according to one aspect of this description, a fuel regulation system for a turbomachine is proposed, the system comprising: a main pumping device comprising a discharge suitable for connection to a combustion chamber and to a variable geometry of the turbomachine in order to ensure a fuel supply, the main pumping device comprising a first main centrifugal pump comprising a rotor part and a stator part; a transmission device configured to modulate the drive speed of the rotor part of the first main centrifugal pump relative to the stator part of the first main centrifugal pump, the transmission device comprising: an epicyclic gear train comprising a sun pinion, a ring gear, a series of satellites meshed by the sun pinion and the ring gear, and a satellite carrier on which the series of satellites is mounted, in which: The crown is connected to the rotor section of the first main centrifugal pump and configured to drive the rotor section of the first main centrifugal pump in rotation relative to the stator section of the first main centrifugal pump; and The planet carrier is suitable for connection to an accessory gearbox of the turbomachine to be driven in rotation by the accessory gearbox, so that the drive speed of the first main centrifugal pump is modulated according to the operating regime of the turbomachine; and an electric machine connected to the solar pinion of the epicyclic train and configured to drive the solar pinion in rotation, so that the drive speed of the first main centrifugal pump is further modulated according to a regime of the electric machine; an auxiliary pumping device comprising a discharge; and a switching device configured to connect the discharge of the auxiliary pumping device to the combustion chamber and variable geometry according to a fuel pressure at the discharge of the main pumping device.

[0007] Advantageously, but optionally, the system may include at least one of the following features, taken alone or in any combination: - the switching device is configured to connect the discharge of the auxiliary pumping device to the combustion chamber and variable geometry when the fuel pressure at the discharge of the main pumping device is below a threshold; - within the system: The auxiliary pumping device includes a piston pump comprising a discharge adapted to be connected to a nozzle of the turbomachine in order to supply it with fuel; and The switching device includes: an auxiliary conduit connecting the piston pump discharge to the combustion chamber and variable geometry; and a valve arranged on the auxiliary conduit and configured to allow fluid flow from the piston pump discharge to the combustion chamber and with variable geometry depending on the fuel pressure at the discharge of the main pumping device; - the piston pump further comprises a rotor part and a stator part, the rotor part of the piston pump being able to be connected to the accessory housing to be driven in rotation, by the accessory housing, relative to the stator part of the piston pump; - the main pumping device further includes a second main centrifugal pump mounted in series with the first main centrifugal pump and comprising a rotor part and a stator part, the ring of the mechanical differential being further connected to the rotor part of the second main centrifugal pump and configured to drive the rotor part of the second main centrifugal pump in rotation relative to the stator part of the second main centrifugal pump, so that a drive speed of the rotor part of the second main centrifugal pump relative to the stator part of the second main centrifugal pump is modulated according to the operating speed of the turbomachine and the speed of the electric machine; - the system also includes: a direct current power supply; and a converter connecting the direct current power supply to the electrical machine; and - the system further includes a centrifugal afterburner pump comprising a rotor part, a stator part and a discharge, the rotor part of the centrifugal afterburner pump being able to be connected to the accessory housing to be driven in rotation, by the accessory housing, relative to the stator part of the centrifugal afterburner pump, the discharge of the centrifugal afterburner pump being able to be connected to an afterburner chamber of the turbomachine in order to supply it with fuel.

[0008] According to another aspect, a turbomachine comprising: is proposed a combustion chamber; variable geometry; and a system such as previously described, in which the discharge of the first main centrifugal pump is connected to the combustion chamber and variable geometry in order to ensure the supply of fuel.

[0009] According to another aspect, a method for controlling a system as previously described is proposed, the method comprising controlling the electrical machine and the switching device as a function of the fuel pressure at the discharge of the main pumping device. DESCRIPTION OF THE FIGURES

[0010] Other features, purposes and advantages will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0011] Fig. 1 illustrates an aircraft schematically.

[0012] Fig. 2 is a schematic cross-sectional view of an aircraft engine.

[0013] Figure [Fig. 3] schematically illustrates a fuel regulation system.

[0014] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION Aircraft

[0015] An aircraft 100 is a device configured to rise and move through the air, and may, for example, be a civil or military airplane, or even a helicopter. An aircraft 100 comprises an airframe which, in the case of an airplane, consists of a fuselage, a wing comprising two wings, tail assemblies, flight controls, and landing gear. Propulsion system

[0016] A propulsion system 1 (or turbomachine) has a principal direction extending along a longitudinal axis XX. The propulsion system 1 is configured to be fixed to the airframe of an aircraft 100, for example under its wings, in the case of an airplane, by means of a pylon (or mast). The propulsion system 1 can also be mounted on the wing of the airplane or at the rear of its fuselage, or even be integrated into its fuselage.

[0017] The propulsion system 1 may be a twin-body, twin-flow, direct-drive, afterburning turbojet, as described below, but may also have a different number of bodies and / or flows, and / or be another type of turbojet, such as a geared turbojet or a turboprop, with or without afterburning.

[0018] Unless otherwise specified, the terms "upstream" and "downstream" refer to the overall direction of airflow through the propulsion system 1 in operation. Similarly, an axial direction corresponds to the direction of the longitudinal axis XX, and a radial direction is a direction perpendicular to the longitudinal axis XX and intersecting it. Furthermore, an axial plane is a plane containing the longitudinal axis XX, and a radial plane is a plane perpendicular to the longitudinal axis XX. A circumference is understood to be a circle lying on a radial plane and whose center lies on the longitudinal axis XX. A tangential or circumferential direction is a direction tangent to a circumference: it is perpendicular to the longitudinal axis XX but does not pass through it.Finally, the adjectives "interior" (or "internal") and "exterior" (or "external") are used with reference to a radial direction, such that the interior part of an element is, along a radial direction, closer to the longitudinal axis XX than the exterior part of the same element.

[0019] The propulsion system 1 comprises, from upstream to downstream, a blower 10, a compression section 12, comprising a low-pressure compressor 120 and a com high pressure press 122, a combustion chamber 14 and a turbine section 16, comprising a high pressure turbine 162 and a low pressure turbine 160. The propulsion system further comprises an afterburner chamber 18 and a nozzle 19.

[0020] The compressor section 12 comprises a series of stages, each including a rotating impeller (rotor) in front of a stationary impeller (stator). The turbine section 16 also comprises a series of stages, each including a stationary impeller (stator) behind which a rotating impeller (rotor) is located.

[0021] The combustion chamber 14 includes a fuel injection rail and a plurality of ignition injectors. The injection rail and / or the ignition injectors are components of the propulsion system 1 that consume fuel. A dedicated circuit supplies the injection rail and / or the ignition injectors of the combustion chamber 14 to ensure combustion, the different combustion stages determining different levels of fuel injection pressure within this circuit.

[0022] The afterburner chamber 18 includes a channel attached to and fixed to the nozzle 19, extending it axially upstream, with afterburner injectors arranged within the channel. The afterburner injectors are other components of the propulsion system 1 that consume fuel. A dedicated circuit supplies the afterburner injectors to ensure afterburning, the different stages of afterburning determining different levels of fuel injection pressure within this circuit.

[0023] The nozzle 19 can have a variable cross-section and thus comprise a plurality of flaps 191, 192, distributed circumferentially around the longitudinal axis XX. A control device 190, such as a ring of hydraulic cylinders, is then connected to the flaps 191, 192 to actuate them so that they adjust the opening of the airflow they delimit. The actuating fluid for the hydraulic cylinders can be fuel. A dedicated circuit supplies, if necessary, the control device 190 to ensure its actuation, the different levels of actuation of the control device 190 determining different levels of activation pressure of the fluid within this circuit.

[0024] The blower 10, the rotor portion of the low-pressure compressor 120, and the rotor portion of the low-pressure turbine 160 are connected by a low-pressure shaft 170 extending along the longitudinal axis XX, the blower 10, the low-pressure compressor 120, the low-pressure shaft 170, and the low-pressure turbine 160 thus forming a low-pressure unit 10, 120, 160, 170. The rotor portion of the high-pressure compressor 122 and the rotor portion of the high-pressure turbine 162 are connected together by a high-pressure shaft 172 extending along the longitudinal axis XX, the high-pressure compressor 122, the high-pressure shaft 172 and the high-pressure turbine 162 then form a high-pressure body 122,162,172. The low-pressure shaft 170 is generally housed, over a section of its length, in the high-pressure shaft 172 and is coaxial with the high-pressure shaft 172.

[0025] The high-pressure compressor 122, the combustion chamber 14 and the turbine section 16 are surrounded by a first housing 151, while the blower 10, the low-pressure compressor 120 and the afterburner chamber 18 are surrounded by a second housing 152. The second housing 152 also surrounds the first housing 151, that is to say, it extends radially outside the first housing 151, all around the longitudinal axis XX. The second casing 152 can be brought and fixed to the airframe of the aircraft 100, for example by being integrated into the fuselage, the first casing 151 being connected to the second casing 152 in a fixed manner, the stator parts of the compression section 12 and the turbine section 16, the combustion chamber 14 and the afterburner chamber 18 also being connected to the first casing 151 in a fixed manner.

[0026] The longitudinal axis XX forms the axis of rotation for the blower 10, the rotor part of the compression section 12 and the rotor part of the turbine section 16, which are capable of being driven in rotation around the longitudinal axis XX relative to each of the first casing 151 and the second casing 152.

[0027] The propulsion system 1 also includes at least one accessory gearbox 30, called AGB (for "Accessory gear box" in Anglo-Saxon terminology), which can be fixedly mounted relative to the second casing 152. The accessory gearbox 30 includes a set of rotating elements, such as gears, for driving a plurality of shafts in rotation around their own axis, accessories being mounted on these shafts to derive useful mechanical power from their rotation. The gear set is itself driven by means of a power take-off shaft connecting, possibly via a transfer case, the accessory case 30 to at least one of the high-pressure body 122, 162, 172, and the low-pressure body 10, 120, 160, 170, typically by being meshed with at least one of the high-pressure shaft 172 and the low-pressure shaft 170.In this way, mechanical power is likely to be taken from at least one of the high-pressure body 122, 162, 172, and the low-pressure body 10, 120, 160, 170, to be delivered to at least one of the accessories via the accessory box 30.

[0028] The propulsion system 1 comprises a number of components (or equipment) configured to be actuated by means of fuel. More specifically, these components are hydraulically actuated and it is intended to use pressurized fuel. to ensure their operation. These components are usually referred to as "variable geometry equipment (or accessories) 14'" or, more simply, "variable geometries 14'". Examples of variable geometries 14' include: variable pitch vanes (e.g., stator vanes of the high-pressure compressor 122), and discharge valves for the primary flow A or secondary flow B (described below). These variable geometries 14' therefore require hydraulic energy linked to fuel pressure to operate. However, unlike an injector in the combustion chamber 14 or the afterburner chamber 18, variable geometries 14' do not consume fuel, as they do not degrade it through combustion.A dedicated circuit powers the 14' variable geometries to ensure their actuation; the different actuation levels of the 14' variable geometries determine different activation pressure levels for each of the 14' variable geometries.

[0029] The circuits dedicated to supplying fuel to the variable geometries 14', the combustion chamber 14, the afterburner chamber 18 and the nozzle 19 (e.g., its control device 190 and / or its flaps 191, 192) can be independent of each other, or be common in whole or in part.

[0030] A controller may also be provided to interface between the propulsion system 1 and the aircraft 100, and also to control the propulsion system 1. Typically, the controller may perform the following functions: regulating the flow of the various fluids necessary for the operation of the propulsion system 1, starting the propulsion system 1, transmitting various measured parameters from the propulsion system 1 to the cockpit of the aircraft 100, managing thrust or reverse thrust, etc. Such a controller may implement digital control and include a computer, memory, and various data exchange channels that interact with each other. Typically, the controller may be of the FADEC type (for "Full Authority Digital Engine Control" in Anglo-Saxon terminology).

[0031] During operation, the blower 10 and the low-pressure compressor 120 draw in an airflow, a portion of which, circulating within a primary stream A that passes through the propulsion system 1, is successively compressed within the high-pressure compressor 122, ignited within the combustion chamber 14 by fuel combustion, and expanded within the turbine section 16 before being transferred to the afterburner chamber 18. Another portion of the airflow circulates within a secondary stream B, which takes an elongated annular shape surrounding the first casing 151 and the afterburner chamber 18. An upstream portion of the second casing 152 defines an air inlet through which the blower 10 and the low-pressure compressor 120 draw in the airflow circulating through the propulsion system 1. A downstream portion of the second casing 152 defines, with the first crankcase 151 and the afterburner chamber 18, then the nozzle flaps 191, 192, and the secondary flow B. Between the turbine section 16 and the afterburner chamber 18, the flow from the primary flow A can mix with the flow from the secondary flow B, typically to enrich it with oxygen. Within the afterburner chamber 18, air can flow before being ejected from the propulsion system 1 to generate thrust, or fuel can be vaporized into the airflow. This is because the air circulating within the afterburner chamber 18 has a high velocity and still contains enough oxygen to cause combustion. The flames created by the afterburner stabilize a little further downstream in one or more toroidal channels of the afterburner chamber 18, called flame catchers, which retain gas recirculation nuclei in their wake. A boost of thrust due to this new combustion can thus be obtained.The nozzle 19 guides the airflow downstream of the propulsion system 1 to enhance thrust. The variable nature of the nozzle 19 allows for a thrust increase regardless of the operating regime of the propulsion system 1, i.e., with or without the use of afterburner. The resulting thrust can, for example, be used to benefit the aircraft 100 to which the propulsion system 1 is attached. Fuel regulation system

[0032] In order to manage the fuel supply to fuel-consuming components, such as the injectors of the combustion chamber 14 and the afterburner chamber 18, the variable geometries 14' and the nozzle 19, which is as close as possible to their need, the propulsion system 1 includes a fuel regulation system 2. Insofar as the fuel regulation system 2 is configured to meet the strict fuel supply requirement, its thermal rejections are reduced, or even eliminated, which improves its efficiency, particularly when it is connected to a heat exchanger system of the propulsion system 1.

[0033] The fuel regulation system 2 comprises a plurality of pumps 22, 24, 26, 28 connected to each other by a hydraulic circuit 200.

[0034] The fuel regulation system 2 further includes a fuel source 20 intended to supply fuel for the actuation of the variable geometries 14' and the nozzle 19, and for combustion within the combustion chamber 14 and the afterburner chamber 18. The fuel source 20 may be a tank intended to store fuel or a fuel supply circuit.

[0035] Among the plurality of pumps 22, 24, 26, 28, the fuel regulation system 2 includes a lift pump 28, preferably of the centrifugal type, for pressurizing the circuit 200. In this regard, the lift pump 28 is connected to the fuel source 20 and configured to deliver fuel admitted from the fuel source 20 to the circuit 200.

[0036] The fuel regulation system 2 further comprises a main pumping device 22, the inlet of which is connected, where applicable, to the lift pump 28. The outlet of the main pumping device 22 is connected to at least one fuel-consuming component, preferably at least one of the combustion chamber injectors 14 and / or to at least one variable geometry 14', in order to ensure, at least in part, their fuel supply. The main pumping device 22 comprises at least one centrifugal pump and, preferably, two centrifugal pumps mounted in series, which improves the efficiency of the main pumping device 22.The use of centrifugal pumps, rather than positive displacement pumps, particularly in a fuel regulation system designed to meet strict fuel supply requirements, allows for a more compact and lighter system. This is primarily because, unlike positive displacement pumps, centrifugal pumps do not require oversized bearings for low flow rate operation. Indeed, a centrifugal pump does not need to operate at low speeds to deliver a low flow rate, but rather functions as a pressure source. Consequently, the fuel regulation system can be used in propulsion systems requiring a fuel supply with highly variable flow rates, regardless of the propulsion system's operating conditions. Furthermore, a centrifugal pump is more robust than a positive displacement pump.Where applicable, the inlet port of the centrifugal pump, or of the first centrifugal pump, is connected to the outlet port of the fuel pump 28, and the outlet port of the centrifugal pump, or of the second centrifugal pump, is connected to the fuel-consuming component and / or to at least one variable geometry 14', the outlet port of the first centrifugal pump being connected to the inlet port of the second centrifugal pump. In this respect, the supply circuit of the variable geometry 14' may be arranged in parallel with the main pumping device 22 or only with the second centrifugal pump of the main pumping device 22.

[0037] The fuel regulation system 2 includes a valve 36 positioned between the discharge port of the main pumping device 22 and the fuel-consuming component and / or at least one variable geometry 14'. The valve 36 has a pressure drop controlled by a flow meter 37. The valve 36 is controllable and is intended, in particular, to be controlled so as to induce a low pressure drop at the discharge of the main pumping device 22 at propulsion system 1 operating regimes where the flow rate discharged by the main pumping device 22 is low and the pressure requirement of the variable geometries 14' is greater than the pressure requirement of the combustion chamber 14. If the fuel regulation system 2 were not configured to ensure the strict requirement of fuel supply, valve 36 would also be controlled to generate a pressure drop, sometimes significant, and source of thermal rejections, at the operating regimes of the propulsion system 1 where the flow discharged by the main pumping device 22 is greater than the needs of the fuel-consuming component and / or the variable geometries 14'.

[0038] Furthermore, the fuel regulation system 2 includes an auxiliary pumping device to support the main pumping device 22 in order to meet the pressure requirements of the fuel-consuming component and / or at least one of the variable geometries 14', at low propulsion system 1 regimes.

[0039] The auxiliary pumping device may include a piston pump 24, preferably a piston pump with variable displacement and, more preferably, self-regulating in flow and pressure. The discharge port of the piston pump 24 is connected to the nozzle 19 to supply it with fuel and thus ensure the actuation of the flaps 191, 192 of the nozzle 19. The piston pump 24 is mounted in parallel with the main pumping device 22, that is, arranged so that its inlet port is connected to the fuel pump 28.

[0040] Furthermore, the fuel regulation system 2 includes a switching device configured to connect the discharge of the auxiliary pumping device to the fuel-consuming component and / or to at least one variable geometry 14' as a function of the fuel pressure at the discharge of the main pumping device 22. More specifically, the switching device is configured to connect the discharge of the auxiliary pumping device to the fuel-consuming component and / or to at least one variable geometry 14' when the fuel pressure at the discharge of the main pumping device 22 is below a threshold. Thus, at low propulsion system 1 speeds, the auxiliary pumping device is able to support the main pumping device 22 in order to meet the pressure requirements of the fuel-consuming component and / or at least one of the variable geometries 14'.The switching device may include an auxiliary conduit connecting the discharge port of the piston pump 24 to the fuel-consuming element and / or to at least one variable geometry 14', and a valve 38 arranged on the auxiliary conduit and configured to allow fluid flow from the discharge port of the piston pump 24 to the fuel-consuming element and / or to at least one variable geometry 14' depending on the fuel pressure at the discharge of the main pumping device 22, and more specifically when the fuel pressure at the discharge of the main pumping device 22. is below the threshold. The valve 38 can, if necessary, be controlled, preferably by the controller, to regulate the flow of fuel from the discharge port of the piston pump 24 to the fuel-consuming component and / or to at least one variable geometry 14'. More specifically, the valve 38 is then controlled to allow the flow of fuel from the discharge port of the piston pump 24 to the fuel-consuming component and / or to at least one variable geometry 14', when the main pumping device 22 is unable to provide the injection pressure necessary for the operation of the combustion chamber 14 and / or the activation pressure necessary for the actuation of variable geometries 14'.A non-return valve may be provided at the discharge of the main pumping device 22, to protect the centrifugal pumps when, at low propulsion system 1 speeds, the auxiliary pumping device delivers to the fuel-consuming component and / or at least one variable geometry 14'.

[0041] Furthermore, the fuel regulation system may include an afterburner pump 26, preferably of the centrifugal type. The discharge port of the afterburner pump 26 is connected to the injectors of the afterburner chamber 18 in order to ensure, at least in part, its fuel supply at a predetermined pressure.The afterburner pump 26 can be mounted in parallel with the main pumping device 22, where applicable only in parallel with the second centrifugal pump of the main pumping device 22, i.e. arranged so that its inlet port is connected to the feed pump 28, where applicable to the discharge port of the first centrifugal pump of the main pumping device 22, or, alternatively, be mounted in series with the main pumping device 22, i.e. arranged so that its inlet port is connected to the discharge of the main pumping device 22.In the parallel arrangement, the afterburner centrifugal pump 26 independently supplies fuel to the injectors of the afterburner chamber 18, while in the series arrangement, the afterburner centrifugal pump 26 participates in supplying fuel to the injectors of the afterburner chamber 18, in support of the main pumping device 22.

[0042] It should be noted that, in certain cases, the fuel regulation system 2 may not have a centrifugal afterburner pump 26. In such cases, the main pumping device 22 alone supplies fuel to the injectors of the afterburner chamber 18, the discharge from the main pumping device 22 being, where applicable, connected to the injectors of the afterburner chamber 18. Optionally, the piston pump 24 may also contribute to supplying fuel to the injectors of the afterburner chamber 18, the fuel discharged by the piston pump 24 to injectors of the combustion chamber 14 and / or to at least one variable geometry 14' which can then also circulate to the injectors of the afterburner chamber 18.

[0043] Each of the pumps 22, 24, 26, 28 comprises a rotor part and a stator part, the rotor part being mobile in rotation relative to the stator part, the rotational speed of the rotor part relative to the stator part determining a drive regime of the pump 22, 24, 26, 28.

[0044] The rotational drive of the rotor part, relative to the stator part, of each of the pumps 22, 24, 26, 28, is implemented by mechanical extraction.

[0045] To do this, a gear from the accessory housing 30 is connected to the rotor part of the piston pump 24 and another, or the same, gear from the accessory housing 30 is connected to the rotor part of the afterburner pump 26 to drive it in rotation relative to the stator part.

[0046] A transmission device 3 is arranged between the accessory housing 30 and the main pumping device 22, in order to modulate the speed of the centrifugal pumps of the main pumping device 22 according, in particular, to the operating speed of the propulsion system 1. This transmission device 3 thus makes it possible, even at low operating speeds of the propulsion system 1, to ensure the supply of fuel to the fuel-consuming parts, typically for the activation of the variable geometries 14'.

[0047] The transmission device 3 includes a mechanical differential 31, an electric machine 32, an electrical power supply 33 and, where applicable, a converter 34.

[0048] The mechanical differential 31 comprises two inputs 311, 312 and one output 310.

[0049] The first input 311 is connected to the accessory housing 30, more precisely to a gear of the accessory housing 30, to be driven in rotation. Thus, a rotational speed of the first input 311 corresponds to a speed of the body of the propulsion system 1 from which the accessory housing 30 derives mechanical power, possibly corrected by a reduction or multiplication factor introduced by the accessory housing 30 and / or by any type of reducing or multiplying device that can be arranged between the accessory housing 30 and the first input 311.

[0050] The second input 312 is connected to the electric machine 32 to be driven in rotation. Thus, a rotational speed of the second input 312 corresponds to a speed of the electric machine 32, which is configured to inject or extract mechanical power within the mechanical differential 31 by transmitting a given torque, at a given speed, to the second input 312.

[0051] The output 310 is connected to the rotor of each of the centrifugal pumps of the main pumping device 22 and, where applicable, of the feed pump 28, to drive it in rotation relative to its stator. Thus, a rotational speed The output of the mechanical differential 31 corresponds to a regime of the centrifugal pump 22, 28 to which the output 310 of the mechanical differential 31 is connected.

[0052] The mechanical differential 31 is preferably an epicyclic gear train comprising a sun pinion 312, centered on an axis of rotation of the mechanical differential 31, a ring gear 310 coaxial with the sun pinion 312 and a series of planet gears distributed circumferentially around the axis of rotation between the sun pinion 312 and the ring gear 310, each planet gear being internally meshed with the sun pinion 312 and externally with the ring gear 310. The series of planet gears is mounted on a planet carrier 311.

[0053] Each of the solar pinion 312, the ring 310 and the satellite carrier can act as an input 311, 312 or an output 310 of the mechanical differential 31.However, it is preferably the ring 310 which acts as output 310 so that a rotation of the ring 310 around the axis of rotation of the mechanical differential 31 causes a rotation of the rotor part of the centrifugal pump 22, 28 relative to its stator part, the planet carrier 311 which acts as first input 311 so that a rotation of the gear of the accessory case 30 to which the planet carrier 311 is connected causes a rotation of the planet carrier 311 around the axis of rotation of the mechanical differential 31, and the solar pinion 312 which acts as second input 312 so that a rotation of an output shaft of the electric machine 32 to which the solar pinion 312 is connected causes a rotation of the solar pinion 312 around the axis of rotation of the mechanical differential 31.This configuration is indeed the one that best preserves the electric machine 32 and the various rotating parts 310, 311, 312 of the mechanical differential, regardless of the operating regime of the propulsion system 1, that is to say regardless of the drive speed of the accessory gearbox 30 and the speed of the centrifugal pumps 22, 28. Indeed, the maximum speed that can be reached by the accessory gearbox 30 is always lower than the speed of the centrifugal pump 22, 28 to which the output 310 is connected.

[0054] The power supply 33 is configured to exchange electrical power with the electric machine 32. The electric machine 32 is configured to transform electrical power received from the power supply 33 into mechanical power to be injected into the mechanical differential 31, via a torque supplied, at a given speed, by its output shaft to the second input 312 of the mechanical differential 31. The electric machine 32 is also configured to extract mechanical power from the mechanical differential 31, via a braking torque supplied to the second input 312 of the mechanical differential 31 by its output shaft, and to transform this extracted mechanical power into electrical power supplied to the power supply 33, which is capable of storing it. In this way, the main pumping device 22 is able to deliver the strict fuel supply requirement to the fuel-consuming parts and / or to at least one variable geometry 14', in particular thanks to the control of the drive speed of the electric machine 32 as a function of the flow rate recorded by the flow meter 38.

[0055] The power supply 33 may be alternating current or direct current, such as a battery. In the latter case, the transmission device 3 may further include a converter 34 connecting the direct current power supply 33 to the electric machine 32 and configured to convert an electrical signal emitted in direct form by the direct current power supply 33 into an alternating current electrical signal to be transferred to the electric machine 32.

[0056] During operation, when the fuel pressure at the discharge of the main pumping device 22 exceeds the requirement of the fuel-consuming component and / or at least one variable geometry 14', the electric machine 32 is driven in a braking mode to reduce the drive speed of the centrifugal pumps of the main pumping device 22. This reduces the pressure delivered by the main pumping device 22, since the pressure delivered by a centrifugal pump is proportional to the square of its drive speed. Furthermore, when the electric machine 32 is driven at zero speed, the drive speed of the pumps of the main pumping device 22 is directly correlated to the speed of the propulsion system 1, via the reduction gearbox 30 and the transmission device 3.The fuel regulation system 2 is sized so that, when the electric machine 32 is driven at zero speed, the drive speed reached by the pumps of the main pumping device 22 is sufficient to ensure the delivery of a pressure corresponding to the needs of the fuel-consuming component and / or at least one variable geometry 14', and this for all operating regimes of the propulsion system 1, except low regimes where the auxiliary pumping device is provided to provide support.This sizing is achieved taking into account two constraints: the pumps of the main pumping device 22 are chosen so that their maximum drive speed is not reached in order to meet the flow variability required at each of the different drive regimes of the propulsion system 1, and the electric machine 32 and the transmission device 3 are chosen so that the maximum braking speed of the electric machine 32 does not exceed its maximum drive speed. In this operating mode of the fuel regulation system 2, the electric machine 32 operates only in a braking mode, i.e., as an electric generator, with the power supply 33 serving as a storage battery. This is particularly important. advantageous in case of blockage of the transmission device 3 or failure of the electric machine 32. Indeed, the excess pressure is, in this case, released by the valve 36.

[0057] In an operating mode where the auxiliary pumping device is absent, the electric machine 32 is intended to operate in a motor mode at the speeds of the propulsion system 1 at which the pressure delivered by the main pumping device 22 is too low relative to the needs of the fuel-consuming component and / or at least a variable geometry 14'. This operating mode has the advantage of reducing the braking power of the electric machine 32, and therefore its mass and size.

[0058] In any event, it is possible to avoid sizing the fuel regulation system 2 so that, when the electric machine 32 is driven at zero speed, the pressure delivered by the main pumping device 22 is sufficient to meet the needs of the fuel-consuming component and / or at least one variable geometry 14', regardless of the operating speed. Indeed, such sizing would inevitably lead to exceeding the maximum drive speeds of the centrifugal pumps of the main pumping device 22 at high operating speeds of the propulsion system 1 and would therefore require oversizing the electric machine 32 to sufficiently dampen them.

[0059] Thanks to the fuel regulation system 2, it is thus possible to implement a fuel regulation process within the propulsion system 1 in which, regardless of the operating conditions of the body of the propulsion system 1 from which the accessory housing 30 draws mechanical power, the speed of the centrifugal pumps of the main pumping device 22 is adjusted to the correct pressure requirement of the combustion chamber 14 and / or the variable geometries 14', while respecting the braking power limitation of the electric machine 32, but also its maximum drive speed limitation, and the maximum drive speed limitation of the centrifugal pumps of the main pumping device 22, and without penalizing the mass and size of the centrifugal pumps of the main pumping device 22.

Claims

Demands

1. Fuel regulation system (2) for a turbomachine (1), the system (2) comprising: a main pumping device (22) comprising a discharge suitable for being connected to a combustion chamber (14) and to a variable geometry (14') of the turbomachine (1) in order to ensure a supply of fuel, the main pumping device (22) comprising a first main centrifugal pump comprising a rotor part and a stator part; a transmission device (3) configured to modulate the drive speed of the rotor portion of the first main centrifugal pump relative to the stator portion of the first main centrifugal pump, the transmission device (3) comprising: an epicyclic gear train (31) including a sun pinion (312), a ring gear (310), a series of planet gears meshed with the sun pinion (312) and the ring gear (310), and a planet carrier (311) on which the series of planet gears is mounted, in which: The ring gear (310) is connected to the rotor portion of the first main centrifugal pump and configured to drive the rotor portion of the first main centrifugal pump in rotation relative to the stator portion of the first main centrifugal pump; and the planet carrier (311) is adapted to be connected to an accessory gearbox (30) of the turbomachine (1) to be driven in rotation by the accessory gearbox (30), so that the drive speed of the first main centrifugal pump is modulated according to the operating regime of the turbomachine (1); and an electric machine (32) connected to the solar pinion (312) of the epicyclic train (31) and configured to drive the solar pinion (312) in rotation, so that the drive speed of the first main centrifugal pump is further modulated according to a regime of the electric machine (32); an auxiliary pumping device comprising a discharge; and a switching device configured to connect the discharge of the auxiliary pumping device to the combustion chamber (14) and to the variable geometry (14') as a function of a fuel pressure at the discharge of the main pumping device (22).

2. System (2) according to claim 1, wherein the com- mutation is configured to connect the discharge of the auxiliary pumping device to the combustion chamber (14) and to the variable geometry (14') when the fuel pressure at the discharge of the main pumping device (22) is below a threshold.

3. System (2) according to any one of claims 1 and 2, wherein: the auxiliary pumping device comprises a piston pump (24) including a discharge adapted to be connected to a nozzle (19) of the turbomachine (1) for the purpose of supplying it with fuel; and the switching device comprises: an auxiliary conduit connecting the discharge of the piston pump (24) to the combustion chamber (14) and to the variable geometry (14'); and a valve arranged on the auxiliary conduit and configured to allow the circulation of fluid from the discharge of the piston pump (24) to the combustion chamber (14) and to the variable geometry (14') as a function of the fuel pressure at the discharge of the main pumping device (22).

4. System (2) according to claim 3, wherein the piston pump (24) further comprises a rotor part and a stator part, the rotor part of the piston pump (24) being able to be connected to the accessory housing (30) to be driven in rotation, by the accessory housing (30), relative to the stator part of the piston pump (24).

5. System (2) according to any one of claims 1 to 4, wherein the main pumping device (22) further comprises a second main centrifugal pump mounted in series with the first main centrifugal pump and comprising a rotor part and a stator part, the ring (310) of the mechanical differential (31) further being connected to the rotor part of the second main centrifugal pump and configured to drive the rotor part of the second main centrifugal pump in rotation relative to the stator part of the second main centrifugal pump, so that a drive speed of the rotor part of the second main centrifugal pump relative to the stator part of the second main centrifugal pump is modulated according to the operating speed of the turbomachine (1) and the speed of the electric machine (32).

6. System (2) according to any one of claims 1 to 5, including further: a direct current power supply (33); and a converter (34) connecting the direct current power supply (33) to the electrical machine (32).

7. System (2) according to any one of claims 1 to 6, further comprising a centrifugal afterburner pump (26) comprising a rotor part, a stator part and a discharge, the rotor part of the centrifugal afterburner pump (26) being able to be connected to the accessory housing (30) to be driven in rotation, by the accessory housing (30), relative to the stator part of the centrifugal afterburner pump (26), the discharge of the centrifugal afterburner pump (26) being able to be connected to an afterburner chamber (18) of the turbomachine (1) in order to supply it with fuel.

8. Turbomachine (1) comprising: a combustion chamber (14); a variable geometry (14'); and a system (2) according to any one of claims 1 to 7, wherein the discharge of the first main centrifugal pump is connected to the combustion chamber (14) and to the variable geometry (14') in order to supply it with fuel.

9. Method of controlling a system (2) according to any one of claims 1 to 7, the method comprising controlling the electric machine (32) and the switching device as a function of the fuel pressure at the discharge of the main pumping device (22).

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