Fuel control system

Abstract

The present invention relates to a fuel control system (4) for an aircraft engine (2), the system (4) comprising: - a pump (411); - a heat exchanger (413); - a recirculation circuit (42); and - a control device (43).

Description

[0001] Fuel control system

[0002] TECHNICAL FIELD

[0003] This presentation concerns the aeronautical field. More specifically, this presentation concerns fuel regulation within an aircraft engine.

[0004] STATE OF THE ART

[0005] Some components of an aircraft engine are cooled by means of a heat transfer fluid. The heat transfer fluid can be any fluid circulated in the engine to cool or lubricate certain parts of the engine, such as lubricating oil or a coolant, for example, an electrical machine coolant. The heat thus stored by the heat transfer fluid is discharged into the fuel sent to the combustion chamber, typically through a heat exchanger arranged within the fuel control system.

[0006] The ability of the fuel to cool the heat transfer fluid depends on the temperature and flow rate of the fuel circulating within the heat exchanger.

[0007] It is therefore necessary to reduce the temperature of the fuel circulating within the heat exchanger, while increasing its flow rate, regardless of the engine speed, to effectively cool the engine components. More specifically, it is necessary to reduce the fuel temperature when the engine is operating at a speed for which the fuel flow is too low, which limits heat exchange, for example, when idling in flight.

[0008] Furthermore, the Applicant is constantly working to reduce the climate impact of aircraft (minimizing greenhouse gas emissions, reducing the environmental footprint of aircraft operation), which involves improving the efficiency of electrical technologies within engines, particularly hybrid engines.

[0009] It is important to ensure the thermal and energy efficiency of cooling circuits within hybrid architecture engines. The need to optimize heat exchanges at the level of heat transfer fluids is therefore particularly present for aircraft engines comprising at least one electrically assisted machine, typically electrically hybridized turbojets, because the cooling of the electrically assisted machine further heats the heat transfer fluid, which stores more heat. GENERAL STATEMENT

[0010] An aim of this disclosure is to improve the heat absorption capabilities of an aircraft engine fuel control system, so as to increase the fuel's ability to cool the heat transfer fluid.

[0011] To this end, according to one aspect of the present disclosure, there is provided a fuel control system for an aircraft engine, the system comprising:

[0012] - a pump comprising an inlet port and a discharge port, the inlet port being adapted to be connected to a fuel source, the discharge port being adapted to be connected to a combustion chamber of the engine to supply fuel to the combustion chamber;

[0013] - a heat exchanger comprising a primary circuit and a secondary circuit, the primary circuit of the heat exchanger having an inlet intended to be connected to the fuel source and an outlet connected to the intake port of the pump, the secondary circuit of the heat exchanger being intended to be connected to a heat transfer fluid circuit of the engine, the heat exchanger being configured to provide heat transfer between fuel circulating in the primary circuit of the heat exchanger and heat transfer fluid circulating in the secondary circuit of the heat exchanger;

[0014] - a recirculation circuit arranged to take fuel discharged through the discharge port of the pump and reinject the taken fuel into the primary circuit of the heat exchanger, the recirculation circuit comprising a regulating valve configured to modulate a flow rate of the fuel circulating within the recirculation circuit; and

[0015] - a control device configured to control the regulating valve as a function of a temperature of the heat transfer fluid circulating in the secondary circuit of the heat exchanger and / or a fuel flow rate at the inlet of the primary circuit of the heat exchanger, so as to increase the heat transfer between the fuel circulating in the primary circuit of the heat exchanger and the heat transfer fluid circulating in the secondary circuit of the heat exchanger.

[0016] Advantageously, but optionally:

[0017] - the control device is configured to control the regulating valve as a function of a pressure difference across the terminals of the regulating valve;

[0018] - the pump is of the volumetric type; - the pump has a variable displacement, the system further comprising a member for controlling the displacement of the pump;

[0019] - the system further comprises a device for controlling a pump drive speed;

[0020] - the regulating valve is further configured to increase the flow rate of fuel circulating within the recirculation circuit in the event of failure of the control member and / or the control device;

[0021] - the system further comprises an additional heat exchanger comprising a primary circuit and a secondary circuit, the secondary circuit of the additional heat exchanger being provided to be connected to an additional circuit of another heat transfer fluid of the engine, the additional heat exchanger being configured to ensure a heat transfer between fuel circulating in the primary circuit of the additional heat exchanger and the other heat transfer fluid circulating in the secondary circuit of the additional heat exchanger;

[0022] - the primary circuit of the additional heat exchanger has an inlet intended to be connected to the fuel source and an outlet connected to the pump inlet port;

[0023] - the primary circuit of the additional heat exchanger has an inlet connected to the pump discharge port and an outlet intended to be connected to the engine combustion chamber.

[0024] According to another aspect of the present disclosure, there is provided an aircraft engine comprising:

[0025] - a system as previously described;

[0026] - a heat transfer fluid circuit connected to the secondary circuit of the system's heat exchanger.

[0027] Advantageously, but optionally:

[0028] - the engine includes:

[0029] - the system as previously described in which the system further comprises an additional heat exchanger comprising a primary circuit and a secondary circuit, the secondary circuit of the additional heat exchanger being provided to be connected to an additional circuit of another heat transfer fluid of the engine, the additional heat exchanger being configured to ensure a heat transfer between fuel circulating in the primary circuit of the additional heat exchanger and the other heat transfer fluid circulating in the secondary circuit of the additional heat exchanger; and

[0030] - an additional circuit of another heat transfer fluid connected to the secondary circuit of the additional heat exchanger of the system;

[0031] - the heat transfer fluid is lubricating oil or a cooling fluid for an electrical machine;

[0032] - the other heat transfer fluid is lubricating oil or a cooling fluid for an electrical machine.

[0033] According to another aspect of the present disclosure, there is provided an aircraft comprising an airframe and an engine, wherein the engine is attached to the airframe.

[0034] According to another aspect of the present disclosure, there is provided a method of regulating fuel for an aircraft engine, the method comprising:

[0035] - a withdrawal of a portion of fuel discharged by a discharge port of a pump of a fuel control system of the engine, the discharge port being connected to a combustion chamber of the engine to supply it with fuel;

[0036] - an injection of the fuel taken from within a primary circuit of a heat exchanger of the system, the heat exchanger comprising the primary circuit and a secondary circuit, the primary circuit of the heat exchanger having an inlet connected to a fuel source of the system and an outlet connected to an inlet port of the pump, the secondary circuit of the heat exchanger being connected to a heat transfer fluid circuit of the engine, the heat exchanger being configured to ensure a heat transfer between fuel circulating in the primary circuit of the heat exchanger and heat transfer fluid circulating in the secondary circuit of the heat exchanger; and

[0037] - modulation of the flow rate of fuel injected into the primary circuit of the heat exchanger so as to increase the heat transfer between the fuel circulating in the primary circuit of the heat exchanger and the heat transfer fluid circulating in the secondary circuit of the heat exchanger.

[0038] Advantageously, but optionally, the method is implemented by the system as previously described.

[0039] DESCRIPTION OF THE FIGURES Other characteristics, aims and advantages will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the attached drawings in which:

[0040] Figure 1 illustrates an aircraft schematically.

[0041] Figure 2 illustrates a schematic sectional view of an aircraft propulsion assembly.

[0042] Figure 3 schematically illustrates a fuel control system.

[0043] Figure 4 schematically illustrates part of a fuel control system.

[0044] Figure 5 schematically illustrates part of a fuel control system according to another alternative.

[0045] Figure 6 is a flowchart illustrating an aircraft engine fuel control process.

[0046] Throughout the figures, similar elements have identical references.

[0047] DETAILED DESCRIPTION

[0048] Aircraft

[0049] An aircraft 100 is a device configured to rise and move in the air, and may, for example, be an airplane, civil or military, or even a helicopter. An aircraft 100 comprises an airframe which, in the case of an airplane, is composed of a fuselage, a wing structure comprising two wings, empennages, flight control surfaces and landing gear.

[0050] Propulsion unit

[0051] A propulsion unit 1 comprises an engine 2 (or turbomachine) and a nacelle 3, and has a main direction extending along a longitudinal axis XX. The propulsion unit 1 is configured to be fixed to the airframe of the aircraft 100, for example under its wings, in the case of an airplane, and this by means of a pylon (or mast). The propulsion unit 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.

[0052] The engine 2 may be a twin-spool, dual-flow, direct-drive ducted turbojet engine, as described below, but may also have a different number of spools and / or flows, and / or be another type of turbojet engine, such as a geared turbojet engine or a turboprop, with or without afterburner, ducted or unducted. Unless otherwise specified, the terms “upstream” and “downstream” are used with reference to the overall direction of airflow through the propulsion unit 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 the longitudinal axis XX. 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 as a circle belonging to a radial plane and whose center belongs to 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 the longitudinal axis XX. Finally, the adjectives "inner" (or "internal") and "outer" (or "external") are used in reference to a radial direction so that the inner part of an element is, in a radial direction, closer to the longitudinal axis XX than the outer part of the same element.

[0053] The engine 2 comprises, from upstream to downstream, a fan 20, a compressor section 22, comprising a low pressure compressor 220 and a high pressure compressor 222, a combustion chamber 24 and a turbine section 26, comprising a high pressure turbine 262 and a low pressure turbine 260.

[0054] The compressor section 22 comprises a succession of stages each comprising a wheel of moving blades (rotor) rotating in front of a wheel of fixed blades (stator). The turbine section 26 also comprises a succession of stages each comprising a wheel of fixed blades (stator) behind which a wheel of moving blades (rotor) rotates.

[0055] The fan 20, the rotor part of the low-pressure compressor 220, and the rotor part of the low-pressure turbine 260 are connected to each other by a low-pressure shaft 280 extending along the longitudinal axis XX, thus forming a low-pressure body 20, 220, 260, 280. The rotor part of the high-pressure compressor 222 and the rotor part of the high-pressure turbine 262 are connected to each other by a high-pressure shaft 282 extending along the longitudinal axis XX, thus forming a high-pressure body 222, 262, 282. The low-pressure shaft 280 is generally housed, over a section of its length, in the high-pressure shaft 282 and is coaxial with the high-pressure shaft 282.

[0056] The compressor section 22, the combustion chamber 24 and the turbine section 26 are surrounded by a motor casing 23, to which the stator parts of the low pressure compressor 220, the high pressure compressor 222, the high pressure turbine 262 and the low pressure turbine 260 are connected, while the fan 20 is surrounded by a fan casing 25. The motor casing 23 and the fan casing 25 are connected to each other by profiled arms 27 forming rectifiers (or OGV for "Outlet Guide Vanes" in English terminology) distributed circumferentially all around the longitudinal axis XX. At least some of these arms 27 can be provided structural.The longitudinal axis XX defines the axis of rotation for the fan 20, the rotor parts of the compressor section 22 and the rotor parts of the turbine section 26, in other words for the low pressure body 20, 220, 260, 280 and the high pressure body 222, 262, 282, which are each capable of being driven in rotation about the longitudinal axis XX relative to the engine casing 23 and the fan casing 25.

[0057] The nacelle 3 extends radially outside the engine 2, all around the longitudinal axis XX, so as to surround both the fan casing 25 and the engine casing 23, and to define, with a downstream portion of the engine casing 23, a downstream portion of a secondary duct B, the upstream portion of the secondary duct B being defined by the fan casing 25 and an upstream portion of the engine casing 23. The upstream portion of the nacelle 3 further defines an air inlet 29 through which the fan 20 sucks in the air flow circulating through the propulsion unit 1. The nacelle 3 is integral with the fan casing 25 and attached and fixed to the aircraft 100 by means of the mast.

[0058] The engine 2 may also comprise at least one accessory box, called ÀGB (for “Accessory gear box” in English terminology), for example housed in a cavity provided within the nacelle 3. The accessory box comprises a set of rotating elements, such as gears, making it possible to drive 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 assembly is itself driven using a power take-off shaft (or RDS for “Radial Drive Shaft” in English terminology) connecting, possibly via a transfer case, the accessory case to at least one of the high pressure body 222, 262, 282 and the low pressure body 20, 220, 260, 280, typically by being meshed with at least one of the high pressure shaft 282 and the low pressure shaft 280.In this regard, the power take-off shaft may extend inside a longitudinal cavity provided within one of the arms 27. In this way, mechanical power may be taken from at least one of the high-pressure body 222, 262, 282 and the low-pressure body 20, 220, 260, 280 to be delivered to the at least one of the accessories via the accessory housing. The combustion chamber 24 comprises a fuel injection rail and a plurality of ignition injectors. The injection rail and / or the ignition injectors constitute fuel-consuming members of the engine 2.

[0059] The engine 2 further 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)” or, more simply, “variable geometries”. Examples of variable geometries are: variable-pitch vanes (e.g., stator vanes of the high-pressure compressor 222), discharge valves of the primary stream A or of the secondary stream B. These variable geometries therefore require hydraulic energy linked to the fuel pressure to operate. However, unlike an injector (ignition or injection rail) of the combustion chamber, the variable geometries do not consume fuel, because they do not degrade it by combustion.

[0060] A controller may also be provided to provide the interface between the engine 2 and the aircraft 100, but also to control the engine 2. Typically, the controller may perform the functions of: regulating the circulation of the various fluids necessary for the operation of the engine 2, starting the engine 2, transmitting various parameters measured from the engine 2 to the cockpit of the aircraft 100, managing thrust or reverse thrust, etc. Such a controller may implement digital-type regulation and include a computer, a 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 English terminology).

[0061] In operation, the fan 20 draws in an air flow, a portion of which, circulating within a primary vein A passing through the engine casing 23 from one side to the other, is successively compressed within the compressor section 22, ignited within the combustion chamber 24 by combustion of fuel, and expanded within the turbine section 26 before being ejected from the engine 2. Another portion of the air flow circulates within the secondary vein B which takes an elongated annular shape surrounding the engine casing 23, the air drawn in by the fan 20 being straightened by the straighteners 27 and then ejected from the propulsion unit 1. In this way, the propulsion unit 1 generates thrust. This thrust can, for example, be used for the benefit of the aircraft 100 on which the propulsion unit 1 is attached and fixed. Fuel regulation system

[0062] In order to manage the supply of fuel to the fuel-consuming organs, such as the injectors (ignition or injection rail) of the combustion chamber 24, and the variable geometries, the engine 2 comprises a fuel regulation system 4.

[0063] The fuel control system 4 comprises a fuel source 40, such as a tank for storing fuel or a fuel supply circuit, provided to supply the fuel for combustion within the combustion chamber 24 and, optionally, for actuation of the variable geometries. In addition, a supply conduit 400 is connected to the fuel source 40.

[0064] The fuel regulation system 4 comprises a main circuit 41 connected to the fuel source 40 via the supply conduit 400, a recirculation circuit 42, connected to the main circuit 41, and a control device 43.

[0065] Advantageously, a centrifugal booster pump 4000, called a low-pressure pump, is interposed between the fuel source 40 and the main circuit 41, on the supply pipe 400, to pressurize the main circuit 41.

[0066] The main circuit 41 comprises an additional pump 411 designed to ensure, at least in part, or even in full, the supply of fuel to the combustion chamber 24, and / or the variable geometries, at the pressure and / or flow rate required by their operation.

[0067] The pump 411 comprises an inlet port 4111 and a discharge port 4112. The pump 411 is arranged such that its inlet port 4111 is connected to the supply conduit 400 to admit fuel from the fuel source 40, possibly previously pressurized by the centrifugal booster pump 4000. The inlet port 4111 of the pump 411 is connected to the supply conduit 400 by a main conduit 410. The pump 411 also comprises a stator portion and a rotor portion, the rotor portion being intended to be driven relative to the stator portion at a certain drive speed.

[0068] The drive of the pump 411 can be implemented by mechanical tapping on one of the low pressure body 20, 220, 260, 280 and the high pressure body 222, 262, 282, possibly via the accessory box. In this case, the drive speed of the pump 411 is directly linked to the speed of the engine 2.

[0069] Alternatively, a mechanical differential may be interposed between the accessory box and the pump 411, to decouple the drive speed of the pump 411 from the speed of the engine 2. In this case, an external motor / generator, electric or not, is also connected to the differential, to allow modulation of the drive speed of the pump 411.

[0070] Alternatively, the drive of the pump 411 is not implemented by mechanical tapping on one of the low pressure body 20, 220, 260, 280 and the high pressure body 222, 262, 282, but is implemented by means of an electric drive motor, the speed of which can be controlled.

[0071] In any event, the decoupling of the drive speed of the pump 411 from the speed of the engine 2 makes it possible to modulate the fuel flow delivered by the pump 411 independently of the speed of the engine 2. In this regard, the fuel regulation system 4 may comprise a device 4114 for controlling the drive speed of the pump 411, which controls the differential or the electric drive motor, if applicable.

[0072] The pump 411 is preferably a volumetric type pump. The pump 411 may also have a variable displacement. In this regard, the fuel regulation system 4 may comprise a control member 4113 which makes it possible to adjust the displacement of the pump 411 and, thus, to modulate the flow rate of fuel delivered by the pump 411 independently of the drive speed of the pump 411.

[0073] The main circuit 41 further comprises a delivery conduit 412 connected to the delivery port 4112 of the pump 411 and to a fuel-consuming member, such as an injector of the combustion chamber 24, so that the latter receives fuel from the pump 411. Thus, at least a portion of the fuel delivered by the pump 411 can be admitted into the combustion chamber 24 to be mixed with the air from the compressor section 22 in order to be ignited.

[0074] Advantageously, the main circuit 41 comprises a regulator 417 positioned on the delivery duct 412. The regulator 417 operates according to the same principle as a hydromechanical group and comprises a flow meter. The regulator 417 is advantageously connected to the control device 4114 and / or to the control member 4113 to control the flow rate of fuel delivered by the pump 411 according to the strict requirements of the combustion chamber 24.

[0075] Advantageously, the main circuit 41 further comprises a filter 415 positioned on the main conduit 410, between the fuel source 40 and the intake port 4110 of the pump 411. The filter 415 makes it possible to treat the fuel circulating within the fuel regulation system 4 in order to optimize its operation.

[0076] Heat exchanger

[0077] The main circuit 41 further comprises a heat exchanger 413 positioned on the main conduit 410, between the fuel source 40 and the inlet port 4110 of the pump 411. The heat exchanger 413 makes it possible to cool a heat transfer fluid using the fuel. The fuel control system 4 is then considered as a cold source capable of absorbing calories from the heat transfer fluid.

[0078] The heat exchanger 413 comprises a primary circuit 4131 and a secondary circuit 4132. The primary circuit 4131 of the heat exchanger 413 has an inlet 4133 connected to the fuel source 40 and an outlet 4134 connected to the inlet port 4110 of the pump 411, via the main conduit 410.

[0079] The secondary circuit 4132 of the heat exchanger 413 is connected to a heat transfer fluid circuit 210 of the engine 2. The heat transfer fluid can be any fluid circulating in the engine 2 to cool or lubricate certain parts of the engine 2, such as lubricating oil or a cooling fluid, such as for example a cooling fluid for an electrical machine.

[0080] The heat exchanger 413 thus ensures a heat transfer between the fuel circulating in the primary circuit 4131 of the heat exchanger 413 and the heat transfer fluid circulating in the secondary circuit 4132 of the heat exchanger 413.

[0081] Thus, such a fuel regulation system 4 makes it possible, among other things, to cool the heat transfer fluid more efficiently. Indeed, by positioning the heat exchanger 413 upstream of the pump 411, the fuel circulating within the primary circuit 4131 is less hot. The heat transfer between the fuel and the heat transfer fluid is therefore improved.

[0082] Advantageously, the main circuit 41 comprises an additional heat exchanger 414. The additional heat exchanger 414 has the same function of cooling a heat transfer fluid by the fuel as the heat exchanger 413. The additional heat exchanger 414 comprises a primary circuit 4141 and a secondary circuit 4142. The primary circuit 4141 of the additional heat exchanger 414 has an inlet 4143 and an outlet 4144.

[0083] According to one embodiment, the additional heat exchanger 414 is positioned upstream of the pump 411, in the direction of circulation of the fuel within the fuel regulation system 4 when the pump 411 is in operation. In other words, the additional heat exchanger 414 is positioned on the main conduit 410, between the fuel source 40 and the inlet port 4110 of the pump 411. The additional heat exchanger 414 can then be arranged in parallel or in series with the heat exchanger 413, upstream or downstream of the heat exchanger 413. Thus, the inlet 4143 of the primary circuit 4141 of the additional heat exchanger 414 is connected either to the fuel source 40 or to the outlet 4134 of the primary circuit 4131 of the heat exchanger 413.And, the outlet 4144 of the primary circuit 4141 of the additional heat exchanger 414 is connected either to the inlet 4133 of the primary circuit 4131 of the heat exchanger 413 or to the inlet port 4111 of the pump 411.

[0084] According to another embodiment, the additional heat exchanger 414 is positioned downstream of the pump 411, in the direction of circulation of the fuel within the fuel regulation system 4 when the pump 411 is in operation, being arranged on the delivery duct 412. In this regard, the inlet 4143 of the primary circuit 4141 of the additional heat exchanger 414 is connected to the delivery port 4112 of the pump 411, and the outlet 4144 of the primary circuit 4141 of the additional heat exchanger 414 is connected to a fuel-consuming member, such as the combustion chamber 24 and / or a variable geometry.

[0085] The secondary circuit 4142 of the additional heat exchanger 414 is connected to a heat transfer fluid circuit 220 which is separate from the heat transfer fluid circuit to which the secondary circuit 4132 of the heat exchanger 413 is connected.

[0086] The main circuit 41 may comprise several additional heat exchangers 414 positioned on the main conduit 410, between the fuel source 40 and the intake port 4110 of the pump 411 and / or on the delivery conduit 412, between the delivery port 4112 of the pump 411 and a fuel consuming member.

[0087] According to one embodiment, the secondary circuit 4132 of the heat exchanger 413 is connected to a lubricating oil circuit and the secondary circuit 4142 of the additional heat exchanger 414 is connected to a cooling fluid circuit for an electric machine.

[0088] According to another embodiment, the secondary circuit 4132 of the heat exchanger 413 is connected to a cooling fluid circuit for an electric machine and the secondary circuit 4142 of the additional heat exchanger 414 is connected to a lubricating oil circuit. The filter 415 can be positioned on the main conduit 410 upstream of the heat exchanger 413 and the additional heat exchanger 414.

[0089] Advantageously, the main circuit 41 further comprises a restriction 416 arranged at the delivery duct 412 and configured to control the fuel flow rate delivered by the pump 411. More specifically, the restriction 416 is configured to generate line losses (or pressure losses), of a thermal nature, within the delivery duct 412, which makes it possible to adjust the fuel flow rate within the duct connecting the delivery duct 412 to the injectors of the combustion chamber 24. The restriction 416 may be a variable-section valve controlled by a servovalve.

[0090] Recirculation circuit

[0091] The fuel regulation system 4 further comprises a recirculation circuit 42. The recirculation circuit 42 comprises a secondary conduit 421 and a regulating valve 422. The recirculation circuit 42 is arranged to take from the delivery conduit 412, by means of the secondary conduit 421, fuel delivered via the delivery port 4112 of the pump 411 and reinject this taken fuel into the primary circuit 4131 of the heat exchanger 413 and / or into the primary circuit 4141 of the additional heat exchanger 414.

[0092] The regulating valve 422 (or “bypass valve” according to English terminology) is mounted on the secondary conduit 421 of the recirculation circuit 42. The regulating valve 422 is configured to regulate the flow rate of the fuel circulating via the secondary conduit 421 into the primary circuit 4131 of the heat exchanger 413 and / or into the primary circuit 4141 of the additional heat exchanger 414.

[0093] The regulating valve 422 is controlled by the control device 43.

[0094] The regulating valve 422 is further configured to regulate the flow rate of fuel delivered through the delivery port 4112 of the pump 411 in the event of failure of the control member 4113 and / or the control device 4114. The recirculation circuit 42 then operates as an overflow of the delivery conduit 412 in order to prevent too high a flow rate of fuel from supplying the combustion chamber 24.

[0095] The regulating valve 422 therefore preferably has a dual function. On the one hand, it allows modulation of the fuel flow circulating within the primary circuit 4131, 4141, the heat exchanger 413, and / or the additional heat exchanger 414. On the other hand, it preferably allows regulation of the fuel flow circulating within the delivery duct 412 and sent to the combustion chamber 24, in the event of failure of the control member 4113 and / or the control device 4114.

[0096] Thus, such a fuel regulation system 4 makes it possible to cool the heat transfer fluid more efficiently. Indeed, the recirculation circuit 42 makes it possible to increase the flow rate of fuel circulating within the primary circuit 4131, 4141, the heat exchanger 413, and / or the additional heat exchanger 414. Such an increase therefore improves the heat transfer between the fuel and the heat transfer fluid.

[0097] Steering device

[0098] The control device 43 is configured to control the regulating valve 422 as a function of a temperature of the heat transfer fluid circulating in the secondary circuit 4132, 4142, of the heat exchanger 413 and / or of the additional heat exchanger 414, of a fuel flow rate at the inlet 4133, 4143, of the primary circuit 4131, 4141, of the heat exchanger 413 and / or of the additional heat exchanger 414, and / or of a pressure difference across the terminals of the regulating valve 422.

[0099] Advantageously, the control device 43 can also be configured to control the regulating valve 422 as a function of the fuel flow circulating within the delivery conduit 412 and sent to the combustion chamber 24, in the event of failure of the control member 4113 and / or the control device 4114.

[0100] Thus, the presence of the regulating valve 422 in the recirculation circuit 42 makes it possible to modulate the flow rate of fuel circulating within the primary circuit 4131, 4141, the heat exchanger 413, and / or the additional heat exchanger 414 as a function of the thermal cooling requirements of the heat transfer fluid and no longer only as a function of the fuel supply requirements of the combustion chamber 24. Furthermore, controlling the regulating valve 422 as a function of the flow rate of fuel circulating within the delivery duct 412 makes it possible to overcome a failure of the control member and / or the control device 4114 and thus avoid excessive transmission of fuel to the combustion chamber 24.

[0101] Fuel regulation process

[0102] A fuel regulation method can be implemented, in particular using a fuel regulation system 4.

[0103] The method firstly implements a sampling E1 of a portion of the fuel, discharged through the discharge port 4112 of the pump 411, using the recirculation circuit 42. The recirculation circuit 42 carries out, by means of the secondary conduit 421, an injection E2 within the primary circuit 4131, 4141, the heat exchanger 413 and / or the additional heat exchanger 414 of the fuel previously sampled.

[0104] The regulating valve 422 implements a modulation E3 of the flow rate of fuel injected into the primary circuit 4131, 4141 of the heat exchanger 413 and / or the additional heat exchanger 414, so as to increase the heat transfer between, on the one hand, the fuel circulating in the primary circuit 4131, 4141 of the heat exchanger 413 and / or the additional heat exchanger 414 and, on the other hand, the heat transfer fluid circulating in the secondary circuit 4132, 4142 of the heat exchanger 413 and / or the additional heat exchanger 414.

[0105] Furthermore, the regulating valve 422 can implement a step E4 of regulating the flow of fuel circulating within the delivery conduit 414 and sent to the combustion chamber 24, in particular in the event of failure of the control member 4113 and / or the control device 4114.

Claims

CLAIMS 1. Fuel control system (4) for an aircraft engine (2) (100), the system (4) comprising: - a pump (411) comprising an intake port (4111) and a discharge port (4112), the intake port (4111) being provided to be connected to a fuel source (40), the discharge port (4112) being provided to be connected to a combustion chamber (24) of the engine (2) to supply the combustion chamber (24) with fuel; - a heat exchanger (413) comprising a primary circuit (4131) and a secondary circuit (4132), the primary circuit (4131) of the heat exchanger (413) having an inlet (4133) intended to be connected to the fuel source (40) and an outlet (4134) connected to the intake port (4111) of the pump (411), the secondary circuit (4132) of the heat exchanger (413) being intended to be connected to a heat transfer fluid circuit (210) of the engine (2), the heat exchanger (413) being configured to ensure heat transfer between fuel circulating in the primary circuit (4131) of the heat exchanger (413) and heat transfer fluid circulating in the secondary circuit (4132) of the heat exchanger (413); - a recirculation circuit (42) arranged to take fuel discharged through the discharge port (4112) of the pump (411) and reinject the taken fuel into the primary circuit (4131) of the heat exchanger (413), the recirculation circuit (42) comprising a regulating valve (422) configured to modulate a flow rate of the fuel circulating within the recirculation circuit (42); and - a control device (43) configured to control the regulating valve (422) as a function of a temperature of the heat transfer fluid circulating in the secondary circuit (4132) of the heat exchanger (413) and / or a fuel flow rate at the inlet (4133) of the primary circuit (4131) of the heat exchanger (413), so as to increase the heat transfer between the fuel circulating in the primary circuit (4131) of the heat exchanger (413) and the heat transfer fluid circulating in the secondary circuit (4132) of the heat exchanger (413).

2. System (4) according to claim 1, in which the control device (43) is configured to control the regulating valve (422) as a function of a pressure difference across the terminals of the regulating valve (422).

3. System (4) according to any one of claims 1 to 2, in which the pump (411) is of the volumetric type.

4. System (4) according to claim 3, in which the pump (411) has a variable displacement, the system (4) further comprising a control member (4113) for the displacement of the pump (411) and / or a control device (4114) for a drive speed of the pump (411).

5. System (4) according to claim 4, wherein the regulating valve (422) is further configured to increase the flow rate of fuel circulating within the recirculation circuit (42) in the event of failure of the control member (4113) and / or the control device (4114).

6. System (4) according to any one of claims 1 to 5, further comprising an additional heat exchanger (414) comprising a primary circuit (4141) and a secondary circuit (4142), the secondary circuit (4142) of the additional heat exchanger (414) being provided to be connected to an additional circuit (220) of another heat transfer fluid of the engine (2), the additional heat exchanger (414) being configured to ensure a heat transfer between fuel circulating in the primary circuit (4141) of the additional heat exchanger (414) and the other heat transfer fluid circulating in the secondary circuit (4142) of the additional heat exchanger (414).

7. Aircraft engine (2) comprising: - a system (4) according to any one of claims 1 to 6; - a heat transfer fluid circuit (210) connected to the secondary circuit (4132) of the heat exchanger (413) of the system (4).

8. Aircraft engine (2) according to claim 7, comprising: - the system (4) according to claim 6; and - an additional circuit (220) of another heat transfer fluid connected to the secondary circuit (4132) of the additional heat exchanger (414) of the system (4).

9. An aircraft (100) comprising an airframe and an engine (2) according to any one of claims 7 and 8, wherein the engine (2) is attached to the airframe.

10. Method for regulating fuel for an aircraft (100) engine (2), the method comprising: - a sampling (E1) of a portion of fuel discharged by a discharge port (4112) of a pump (411) of a fuel regulation system (4) of the engine (2), the discharge port (4112) being connected to a combustion chamber (24) of the engine (2) to supply it with fuel; - an injection (E2) of the fuel taken from within a primary circuit (4131) of a heat exchanger (413) of the system (4), the heat exchanger (413) comprising the primary circuit (4131) and a secondary circuit (4132), the primary circuit (4131) of the heat exchanger (413) having an inlet (4133) connected to a fuel source (40) of the system (4) and an outlet (4134) connected to an intake port (4111) of the pump (411), the secondary circuit (4132) of the heat exchanger (413) being connected to a heat transfer fluid circuit (210) of the engine (2), the heat exchanger (413) being configured to ensure a heat transfer between fuel circulating in the primary circuit (4131) of the heat exchanger (413) and heat transfer fluid circulating in the secondary circuit (4132) of the heat exchanger (413); and - a modulation (E3) of the flow rate of fuel injected into the primary circuit (4131) of the heat exchanger (413) so as to increase the heat transfer between the fuel circulating in the primary circuit (4131) of the heat exchanger (413) and the heat transfer fluid circulating in the secondary circuit (4132) of the heat exchanger (413).

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