IMPROVED CONTROL SYSTEM FOR AN AIRCRAFT PROPULSION UNIT

Abstract

The invention relates to a system (120) for controlling a propulsion unit (1) for an aircraft, the propulsion unit comprising a turbomachine (2) configured to generate a direct thrust flow (50a), as well as a thrust reverser (30), the control system comprising at least one control member (122, 124) operable by an operator. According to the invention, the control system is configured such that when the taxiing speed of the aircraft is less than or equal to a reference speed, the control member (122, 124) can be moved into a position in which the control system orders the thrust reverser (30) to occupy a partial opening configuration between the closed configuration and the open configuration, so as to generate a counterthrust flow of intensity (50b). Figure for abstract: Fig. 2

Description

Title of the invention: IMPROVED SYSTEM FOR CONTROLLING A PROPULSION UNIT FOR AN AIRCRAFT Technical field

[0001] The invention relates to the field of control systems for a propulsion unit for an aircraft, and more particularly to the control of the rolling of the aircraft at low speed. State of the prior art

[0002] During the taxiing phases of an aircraft, also called "taxi phases", this aircraft is propelled by the direct thrust generated by its propulsion units. When the aircraft must be slowed down, for example to make turns or to reduce its speed at runway intersections, brakes are conventionally used which act on the wheels of the aircraft.

[0003] However, intensive use of the brakes is not desirable, as it reduces their service life, particularly when cold in the case of carbon brakes. However, the turbo-machines used on aircraft, particularly commercial aircraft, have high bypass ratios which induce high direct thrust at engine idle speed. This leads to increased use of the aircraft's wheel brakes, with the harmful consequences described above.

[0004] Furthermore, the use of the brakes during taxiing phases can be a source of discomfort for passengers, given that the braking forces are applied to the wheels of the main landing gear, close to the ground. They thus generate a torque on the aircraft which tends to cause the front wheel of the landing gear to dip. This phenomenon is undesirable because it is perceptible in the cabin, with the sensation of a forward rotation for the passengers.

[0005] To overcome these problems, it has been considered to use thrust reversers as a source of braking during taxiing phases, and as a means of limiting thrust when the engine is idling and the aircraft is stationary on the ground. However, this solution has until now been reserved for small aircraft, i.e. essentially business jets. In the case of aircraft with high bypass ratios encountered on turbomachines of commercial aircraft, thrust reversers are not usually used below a taxiing reference speed, also called the reverser cut-off speed and generally set between 50 and 70 knots. Indeed, even in the position of the throttle which controls a counterthrust flow of minimum intensity, the reverser is placed in its open configuration, i.e. its configuration with maximum opening. Below the cut-off speed, the braking force generated by the counter-thrust flow may prove too high compared to the requirements encountered, even when this counter-thrust flow is of minimal intensity. In addition, always below the cut-off speed, the full opening of the inverter creates a risk of re-injection of the counter-thrust flow, as well as a risk of injection of foreign bodies lifted from the ground by this flow, such as gravel.

[0006] Few solutions have so far been provided to address this problem of aircraft braking when taxiing below the cut-off speed, or of reducing thrust at idle, when stopped. For example, a solution has been provided by document FR 3 093 996 A1, disclosing a thrust reverser capable of generating a slowdown of the aircraft by reducing the direct thrust. To do this, a double-grid system is implemented, with a second set of grids having downstream flow direction members, namely opposite the upstream flow redirection members equipping a first set of grids. The first and second sets of grids are alternately deployed, depending on the desired force. This solution nevertheless remains perfectible, both in terms of performance and simplicity of design. Statement of the invention

[0007] To address the drawbacks relating to the embodiments of the prior art, the invention firstly relates to a system for controlling a propulsion unit for an aircraft, the propulsion unit having a longitudinal central axis and comprising a turbomachine configured to generate a direct thrust flow, as well as a thrust reverser configured to adopt:

[0008] - a closed configuration in which the thrust reverser is inactive; and

[0009] - an open configuration in which the thrust reverser is active, the confi open configuration allowing the reverser to deflect at least part of a flow passing through the turbomachine, in order to form a counter-thrust flow escaping from the propulsion unit with an axial direction opposite to that of the direct thrust flow, the control system comprising at least one control member actuable by an operator.

[0010] According to the invention, the control system is configured so that when the taxiing speed of the aircraft is less than or equal to a reference speed, the control member can be moved into a position in which the control system orders the thrust reverser to occupy a partial opening configuration between the closed configuration and the open configuration, so as to generate a counterthrust flow of lower intensity than that generated in the open configuration.

[0011] The invention thus provides a simple and efficient solution, making it possible to brake the aircraft in the taxiing phase below the reference speed, the order of magnitude of which is preferably that usually retained for the cut-off speed of the reversers. Indeed, instead of prohibiting the use of the reverser in the taxiing phase below the reference speed, the invention advantageously provides for controlling the reverser so that it opens only partially, and that it generates a counter-thrust flow of fairly low intensity, meeting the braking needs, and possibly also the need to reduce the thrust produced at idle, when the speed of the aircraft must be maintained at zero. Indeed, the principle of the invention could also be applied when the aircraft is stationary on the ground, to keep it stationary, in order to counteract the thrust generated during an engine idle speed.This thrust can in fact be significant, particularly on commercial aircraft due to the increase in the bypass ratio of the turbomachines equipping these aircraft.

[0012] This design specific to the present invention is also advantageous in that it makes it possible to limit the wear of the wheel brakes. The wear of the reverser caused by its deployment during the rolling phase at low speed also remains contained, since this deployment may only be partial. This leads to lower forces on the parts usually sized for thrust reversal mode, such as the grilles, the door pivots, and the actuators. The service life of these elements is thus advantageously improved.

[0013] Finally, the use of the inverter during the rolling phase, below the reference speed and as a replacement or in addition to the wheel brakes, also makes it possible to improve passenger comfort during braking.

[0014] The invention preferably provides at least one of the following optional technical features, taken alone or in combination.

[0015] Preferably, the control member is a throttle lever capable of being placed in an engine idle position, and moved in a first direction from this engine idle position, towards a full throttle position, and moved in a second direction still from this engine idle position, in a thrust reversal control zone, towards a maximum counterthrust position. In addition, the control system is configured so that when the taxiing speed of the aircraft is less than or equal to the reference speed, the throttle lever can be moved within the thrust reversal control zone into at least one intermediate counterthrust position in which the control system orders the thrust reverser to occupy said partial opening configuration.

[0016] Alternatively, the control member could be a brake pedal. Its actuation, for example from a certain stroke and / or as a function of a speed movement of this pedal by the action of the operator's foot, could lead the control system to order the same action as that described below in the context of the use of the throttle, as well as all or part of the actions which will be described below.

[0017] Preferably, the control system is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle lever is placed in the engine idle position, the control system orders the thrust reverser to occupy a minimum partial opening configuration, so as to generate the counterthrust flow with a minimum intensity, preferably corresponding to the intensity of the direct thrust flow escaping from the turbomachine, so that the propulsion unit generates zero or substantially zero thrust. Also, the invention advantageously provides that in the low-speed taxiing situation, the engine idle position generates a zero or substantially zero force resultant for the propulsion unit. This improves the ease of piloting the aircraft in this particular situation, and reduces brake wear.

[0018] Alternatively, the control system could be configured so that in the engine idle position, the minimum intensity of the counterthrust flow generated by the reverser remains lower or higher than the intensity of the direct thrust flow escaping from the turbomachine, so that the propulsion unit generates low thrust or low counterthrust.

[0019] Preferably, the control system is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle occupies any first intermediate position within a first part of the reversal control zone located between the engine idle position and an intermediate reference position, the control system orders the thrust reverser to occupy a partial opening configuration, the opening level of which is a function of the first intermediate position within the first part of the reversal control zone, so as to generate the counterthrust flow with an intensity greater than that of the direct thrust flow escaping from the turbomachine, so that the propulsion unit generates counterthrust, preferably while maintaining the idle speed.

[0020] Alternatively, in this first part of the reversing control zone between the engine idle position and the intermediate reference position, in addition to continuing to open the reverser, the control system could simultaneously order an increase in the engine speed, rather than keeping it constant at the idle speed.

[0021] Preferably, in the intermediate reference position of the throttle lever, the control system commands the thrust reverser to occupy a configuration maximum rolling opening, corresponding to a maximum partial opening configuration of the inverter, or to its open configuration.

[0022] Preferably, the control system is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle occupies any second intermediate position within a second part of the reversal control zone located between the reference intermediate position and the maximum counterthrust position, the control system orders the thrust reverser to maintain its maximum taxiing opening configuration, and orders the application of an engine speed which is a function of the second intermediate position within the second part of the reversal control zone, so as to generate the counterthrust flow with an intensity greater than that of the direct thrust flow escaping from the turbomachine, so that the propulsion unit generates counterthrust.

[0023] Preferably, said throttle lever is also used for controlling the engine speed in flight, as well as for controlling the thrust reverser on landing. Also, for the same position of the throttle lever in the reverser control zone, the control of the reverser and / or the engine speed may differ depending on the phase in which the aircraft is located, and in particular differ between the landing phase and the phase of taxiing below the reference speed.

[0024] According to an alternative, said throttle lever is provided in addition to a main throttle lever used for controlling the engine speed in flight, as well as for controlling the thrust reverser on landing, the control system then being configured so that the throttle lever has authority over the main throttle lever as soon as the taxiing speed of the aircraft is less than or equal to the reference speed.

[0025] Preferably, the control system further comprises:

[0026] - an engine regulation system connected to the control member so that the position of the latter is transmitted to the regulation system, the latter being configured to deliver opening / closing instructions to the thrust reverser, as well as to deliver engine speed instructions to the turbomachine;

[0027] - a processing unit connected to the engine control system, the processing unit being configured to receive information relating to the taxiing speed of the aircraft, and to transmit this information to the engine control system, for example FADEC, the English acronym for “Full Authority Digital Engine Control”, and corresponding to a digital control system centered on a computer with two symmetrical, redundant and full authority channels.

[0028] The invention also relates to a method for controlling a propulsion unit for an aircraft using such a control system. When the speed of rolling of the aircraft is less than or equal to a reference speed, the thrust reverser is ordered, in response to the placement of the control member in a given position, to occupy a partial opening configuration between the closed configuration and the open configuration, so as to generate a counterthrust flow of lower intensity than that generated in the open configuration.

[0029] Of course, this method is intended to implement all or part of the actions described above in relation to the control system.

[0030] Finally, the invention also relates to an aircraft comprising at least one propulsion unit as well as such a system for controlling this unit, the propulsion unit comprising a turbomachine configured to generate a direct thrust flow, as well as a thrust reverser configured to adopt:

[0031] - a closed configuration in which the thrust reverser is inactive; and

[0032] - an open configuration in which the thrust reverser is active, the confi open configuration allowing the reverser to deflect at least part of a flow passing through the turbomachine, in order to form a counter-thrust flow escaping from the propulsion unit with an axial direction opposite to that of the direct thrust flow.

[0033] Preferably, the thrust reverser of the propulsion unit comprises flow redirection members for generating the counterthrust flow, the control member being a throttle lever, and the reverser is designed so that these same flow redirection members are used both when the lever is placed in a position in which the control system orders the thrust reverser to occupy a partial opening configuration between the closed configuration and the open configuration, and when this lever is placed in a maximum counterthrust position. More generally, it is these same flow redirection members which are preferentially used in whole or in part when the reverser is active, regardless of the position of the throttle lever, the phase in which the aircraft is located, and its speed.

[0034] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. Brief description of the drawings

[0035] The following detailed description refers to the accompanying drawings in which:

[0036] [Fig.l] is a side view of an aircraft;

[0037] [Fig.2] is a schematic view of a turbomachine equipping the aircraft shown in the previous figure, with its control system which is presented in the form of a preferred embodiment of the invention, the half-view from above representing the thrust reverser in the open configuration, and the half-view from below representing the thrust reverser in the closed configuration;

[0038] [Fig.3] is a perspective view of the turbomachine shown in the preceding figure, with its thrust reverser shown in the open configuration;

[0039] [Fig.4] is a schematic top view of a throttle module, fitted the control system shown in [Fig.2];

[0040] [Fig.5] is a diagram representing the control logic of the control system;

[0041] [Fig.6] is a double graph representing, in the upper part, the control of the engine speed as a function of the position of the throttle lever, and representing, in the lower part, the control of the opening of the reverser, still as a function of the position of the throttle lever;

[0042] [Fig.7] is a schematic view in longitudinal half-section of a part of the tower bomachine, and its inverter shown in the configuration as adopted when the aircraft taxiing speed is less than or equal to a reference speed, and with the throttle lever in the engine idle position;

[0043] [Fig.8] is a schematic view in longitudinal half-section similar to the previous one, with the reverser shown in the configuration as adopted when the taxiing speed of the aircraft is less than or equal to a reference speed, and the throttle occupies an intermediate reference position;

[0044] [Fig.9] is a schematic perspective view of part of the system of order, according to an alternative; and

[0045] [Fig. 10] is a schematic longitudinal sectional view of a turbomachine similar to that of [Fig.2], and equipped with a thrust reverser in the form of an alternative. Detailed description of embodiments

[0046] With reference to [Fig. 1], an aircraft 100 is shown, of the commercial aircraft type. This aircraft comprises a fuselage 102, as well as wings 104 (only one being visible in the side view of [Fig. 1]). One or more propulsion units 1 are mounted on each wing 104, preferably in a suspended manner. Each propulsion unit 1 comprises in particular a turbomachine, and a thrust reverser, as will be detailed later.

[0047] At the front, the aircraft has a cockpit 108, in which there are one or more elements of a control system for the propulsion unit 1, such as a throttle module 110, or a brake pedal module 112.

[0048] [Fig. 2] represents one of the propulsion units 1, accompanied by its control system 120 specific to the invention. All the propulsion units 1 of the aircraft are of identical or similar design, and controlled in the same or similar manner. Also, only one of the units 1 will be described below, with its control system 120.

[0049] The propulsion assembly 1 has a longitudinal central axis A1. Subsequently, the terms “upstream” and “downstream” are defined relative to a general direction 15 of flow of the gases through the propulsion assembly 1, along the axis A1 when the latter generates direct thrust. These terms “upstream” and “downstream” could respectively be substituted by the terms “front” and “rear”, with the same meaning.

[0050] The propulsion unit 1 comprises a turbomachine 2, a nacelle 3 as well as a mast (not shown), intended to connect the propulsion unit 1 to a wing of the aircraft.

[0051] The turbomachine 2 is in this example a double-flow, double-spool turbojet engine comprising, from front to rear, a fan 5, a low-pressure compressor 6, a high-pressure compressor 7, a combustion chamber 8, a high-pressure turbine 9 and a low-pressure turbine 10. The compressors 6 and 7, the combustion chamber 8 and the turbines 9 and 10 form a gas generator. The turbojet engine 2 is provided with a fan casing 11 connected to the gas generator by structural arms 12.

[0052] In operation, an air flow 20 enters the propulsion unit 1 through the air inlet 13, passes through the fan 5 and then divides into a primary flow 20A and a secondary flow 20B. The primary flow 20A flows in a primary gas circulation vein 21A passing through the gas generator. The secondary flow 20B flows in a secondary vein 21B surrounding the gas generator. The secondary vein 21B is delimited radially inwardly by a fixed internal fairing 18 which envelops the gas generator. This fairing 18 is an integral part of a fixed structure of a thrust reverser which will be described below. This same fairing is also called a wall 18 for radially internal delimitation of the secondary vein 21B.

[0053] Radially outwards, the secondary vein 21B is delimited by the fan casing 11, and by one or more reverser cowls 33 forming part of the rear section of the nacelle 3.

[0054] The nacelle 3 therefore comprises a thrust reverser 30 centered on the axis A1 and comprising on the one hand a fixed structure 31 secured to the fan casing 11 and comprising the cowls 33, and on the other hand a structure movable relative to the fixed structure 31. In this preferred embodiment of the invention, the reverser is of the door type, that is to say that the movable structure is formed by several movable doors 29, distributed around the axis A1

[0055] In the bottom half-section of [Fig. 2], the inverter 30 adopts a closed configuration, in which the inverter is inactive. In this closed configuration, each door 29 closes a radial opening 35 through the cover 33, and has a radially internal surface which locally reconstitutes the secondary vein 21B, as well as a radially external surface which locally reconstitutes the external surface of the nacelle.

[0056] In this configuration, the thrust reverser 30 does not generate any counterthrust flow, while the turbomachine generates a direct thrust flow 50a corresponding to the addition of the primary and secondary flows 20A, 20B.

[0057] In the top half-section of [Fig. 2], the reverser 30 adopts an open configuration, in which the thrust reverser is active. In this open configuration, each door 29 is deployed to the maximum, thus releasing its associated opening 35. In this open configuration, the deployed doors 29 make it possible to deflect a large part of the secondary flow 20B, in order to form a counter-thrust flow 50b escaping from the propulsion unit 1 through the openings 35, with an axial direction opposite to that of the direct thrust flow 50a, observed in particular in the closed configuration.

[0058] More precisely, in the open configuration, the rear part of each door 29 is immersed in the secondary flow path 21B, preferably up to the internal wall 18, or close to it. This rear part thus forms a member for closing the flow path, in the open configuration of the reverser. In addition, the front part of each deployed door 29 projects radially outwards and axially towards the front of the reverser cover 33. Due to this particular inclination towards the upstream, the front part of each door 29 forms a member for redirecting the flow, making it possible to generate the counter-thrust flow 50b. Still in this open configuration of the reverser, also shown in [Fig. 3], the counter-thrust flow 50b has a higher intensity than that generated by the direct thrust flow 50a which remains.Thus, the resultant of these flows 50a, 50b is such that in its entirety, the propulsion unit 1 generates a maximum counter-thrust braking the aircraft, essentially implemented during its landing.

[0059] To move from one extreme configuration to the other, the inverter 30 is equipped with one or more actuators 37, preferably electric or hydraulic cylinders. These actuators connect the fixed structure 31 of the inverter to each door 29. The axial deployment of the actuator 37 causes its associated door 29 to pivot and plunge into the secondary vein 21B, using known and conventional kinematics.

[0060] Connected to the propulsion unit 1, the aircraft also comprises the control system 120 of this unit.

[0061] The control system 120 comprises the module 110, with its throttle lever 122 forming a control member that can be manually actuated by the operator, from the cockpit. It also comprises the module 112, with its brake pedal(s) 124 that can be actuated by pressure at their upper end by the operator's feet, also from the cockpit. The pedals 124 have the function of activating the aircraft wheel braking, this braking being carried out here in a known and conventional manner. Nevertheless, it is recalled that the pedals, or more precisely the rudder pedals, primarily control the direction, the braking function being carried out by pressure on the upper end of each pedal.

[0062] The control system 120 further comprises an engine regulation system 128, formed by the FADEC which is connected to the control lever 122, so that the position of the latter is transmitted to the regulation system 128. This system 128 is configured to deliver opening / closing instructions to the actuators 37 of the thrust reverser 30, as well as to deliver engine speed instructions to the turbojet 2.

[0063] The control system 120 is completed by a processing unit 130 also connected to the engine control system 128. This unit is configured to receive, via dedicated inputs 132, 134, information relating to the position of the aircraft relative to the ground, for example via monitoring the compression of the shock absorbers of the main landing gear, as well as its speed, and in particular its taxiing speed when it is on the ground. In addition, the unit 130 is designed to transmit this information to the engine control system 128, which then uses it for controlling the propulsion unit 1.

[0064] With reference now to [Fig. 4], the module 110 will be described, and in particular the different positions that the throttle lever 122 can adopt within this module.

[0065] The throttle lever 122 is housed in a rail 136 of the module 110, preferably in the shape of an arc of a circle. This lever 122 can be articulated at its base on the fixed part 138 of the module. This fixed part 138 also incorporates, along the rail 136 in which the lever 122 slides when it is pivoted by the operator, a visual marking of different key positions of this lever.

[0066] Among these key positions, the engine idle 140b, the full throttle for direct thrust 140a, or the maximum counter-thrust 140d are noted. Along the rail 136, a direct thrust control zone 142 is thus provided between the engine idle position 140b, and the full throttle position 140a, offset from the position 140b in a first direction SI of movement of the lever 122 within its rail 136.

[0067] Along the rail 136, a thrust reversal control zone 144 is also provided between the engine idle position 140b and the maximum counter-thrust position 140d, offset from the position 140b in a second direction S1 of movement of the lever 122 within its rail 136. The first direction S1 is opposite to the second direction S2.

[0068] In the thrust reversal control zone 144, a first part 144a and a second part 144b are provided, separated from each other by a position intermediate reference position 140c, the particularity of which will be described later. Also, the first part 144a of the reversing control zone 144 is located between the engine idle position 140b and the intermediate reference position 140c, while the second part 144b of the zone 144 is located between the intermediate reference position 140c, and the maximum counter-thrust position 140d.

[0069] Referring now to Figures 5 to 8, the operation of the control system 120 will be described.

[0070] It is first detected at a step E1 whether the aircraft is on the ground. If not, at a step E2, the position of the lever 122 is determined, which leads to a conventional command. Indeed, if the engine idle position 140b is detected, the system 120 implements an action A1 consisting of ordering the thrust reverser to occupy its closed configuration intended to make it inactive, and ordering the turbojet engine to apply the idle speed. If the detected position is in the direct thrust control zone 142, the system 120 implements an action A2 consisting of ordering the thrust reverser to maintain its closed configuration, and ordering the turbojet engine to apply a speed according to the position of the lever 122. The further this position is from the engine idle position 140b in the direction S1, the higher the speed will be, and the direct thrust flow will be of significant intensity.Finally, if the detected position is in the thrust reverser control zone 144, the system 120 implements an action A3 consisting of ordering the thrust reverser to occupy its open configuration intended to make it active, and ordering the turbojet engine to apply a speed according to the position of the lever 122. The further this position is from the engine idle position 140b in the second direction S2, the higher the speed will be, and the greater the counterthrust flow intensity.

[0071] This control logic is also adopted when the aircraft is on the ground, and is moving at a taxiing speed greater than a reference speed, for example between 50 and 70 knots.

[0072] Obviously, in the control of the aforementioned phases, conventional safety measures can be implemented to limit / prohibit the opening of the thrust reverser in flight, and / or before the aircraft has touched the ground during landing.

[0073] This conventional control of the propulsion unit 1 is shown diagrammatically on the double graph of [Fig.6], by the dotted curve 150 at the top for what concerns the engine speed, and by the dotted curve 152 at the bottom for what concerns the opening of the reverser.

[0074] It is observed that the control principle described above only provides for a complete opening of the thrust reverser 30, or its complete closing. This principle thus contrasts with the control applied when the ground speed is in- lower than or equal to the reference speed, as will be detailed below.

[0075] Indeed, when at a step E3, the rolling speed of the aircraft is detected to be less than or equal to the reference speed, the position of the lever 122 is determined at a step E4, which leads to a command specific to the present invention, involving partial openings of the reverser. In this regard, it is specified that the principle specific to the present invention applies not only to cases of rolling of the aircraft when it is rolling at a speed less than or equal to the reference speed, and / or to keep the aircraft stationary, when its speed is zero. For this reason, the reference speed can be set to up to the value zero.

[0076] If the engine idle position 140b is detected, the system 120 implements an action A4 consisting of ordering the thrust reverser to occupy a minimum partial opening configuration shown in [Fig.7], so as to generate the counterthrust flow 50b with a minimum intensity, preferably corresponding to the intensity of the direct thrust flow 50a escaping from the turbomachine from the primary stream and the secondary stream. The objective sought here is to ensure that the double component of the direct thrust flow 50a and the component of the counterthrust flow 50b cancel each other out, so that the propulsion unit 1 generates zero or substantially zero thrust. This action A4 also consists of ordering the turbojet 2 to apply the idle speed, in order to obtain the desired result.

[0077] This action A4 then preferentially aims to keep the aircraft stationary despite the thrust generated at engine idle speed.

[0078] In the minimal partial opening configuration of [Fig.7], it is shown that the door 29 only releases a small part of the opening 35, by being slightly inclined, and by penetrating only slightly into the secondary vein 21B.

[0079] If the detected position is in the direct thrust control zone 142, a step A5 is implemented, consisting of maintaining the reverser in the closed configuration, and adapting the engine speed according to the position of the throttle lever position.

[0080] If, on the other hand, the detected position is in the thrust reversal control zone 144, the nature of the command ordered by the system 120 will differ depending on the precise position of the lever 122.

[0081] Indeed, if the detected position is any first intermediate position within the first part 144a of the reversal control zone 144, the system 120 implements an action A6 consisting of ordering the thrust reverser to occupy a partial opening configuration, the opening level of which is a function of the first intermediate position within the first part 142a of the zone 142. The further this first intermediate position is from the engine idle position 140b in the second direction S2, the higher the speed will be, and the flow of counterthrust of significant intensity. Here, the objective is to generate the counterthrust flow 50b with an intensity greater than that of the direct thrust flow 50a escaping from the turbojet, so that the propulsion unit 1 generates a counterthrust braking the taxiing of the aircraft. One of the particularities of this action A6 is that it is preferentially implemented by ordering the turbojet to maintain the idle speed. The intensity of the braking counterthrust, depending on the travel of the lever from the engine idle position 140b, thus depends only on the level of partial opening of the reverser.

[0082] As for action A4 and for all other actions causing a partial opening of the reverser, it is noted that the engine control system 128 is configured to send a partial axial deployment instruction to the actuators 37 of the reverser. This is done very simply with electric actuators, and, for hydraulic actuators, only the addition of valves controlled by feedback from a measurement of the position of the door is sufficient, for example.

[0083] Consequently, the instruction delivered to the inverter is to occupy the partial opening configuration, namely to maintain this configuration until a new instruction is received. This contrasts with the inverter simply passing through this partial opening configuration, transiently, when this inverter moves from its closed configuration to its open configuration, or vice versa. In other words, the system controls the inverter so that it starts from the closed configuration, reaches and maintains the desired partial opening configuration, and returns to the closed configuration without having reached the open configuration, unlike what happens in conventional use of the inverter.

[0084] If the detected position is the first intermediate reference position 140c shown in [Fig. 4], the system 120 implements an action A7 consisting of ordering the reverser 30 to occupy a maximum rolling opening configuration, preferably corresponding to a maximum partial opening configuration of the reverser. Here too, a counter-thrust 160 delivered by the propulsion unit 1 is sought as a result of the flows 50a, 50b. Alternatively, in this control logic, it could be authorized to move the doors 29 of the reverser into their maximum deployment configuration, namely placing the reverser in the aforementioned open configuration. Nevertheless, as indicated above, when the rolling speed is less than or equal to the reference speed, it is avoided to fully open the reverser, the latter being able to adopt only a maximum partial opening configuration, shown in [Fig. 8].This maximum partial opening configuration corresponds, for example, to 50% of the maximum opening capacity of the inverter, this percentage can nevertheless vary depending on the identified driving speed.

[0085] Action A7 also consists of ordering the turbojet 2 to maintain the idle speed. But due to the greater opening of the reverser, the counterthrust flow 50b increases in favor of the dual-component direct thrust flow 50a.

[0086] Finally, if the detected position is any second intermediate position within the second part 144b of the reversal control zone 144, the system 120 implements an action A8 consisting of ordering the thrust reverser to maintain its maximum rolling opening configuration. It also orders the turbojet engine to apply an engine speed which is a function of the second intermediate position within the second part 144b of the zone 144. The further this second intermediate position is from the reference intermediate position 140c in the second direction S2, the higher the speed will be, and the greater the counterthrust flow intensity. Here, the objective is to generate the counterthrust flow 50b with an intensity even greater than that obtained with the implementation of the actions A6 and A7, so that the propulsion unit 1 generates an even higher braking counterthrust.

[0087] It is indicated that when the taxiing speed is less than or equal to the reference speed, the maximum engine speed authorized for the counterthrust is preferably lower than that authorized in the phases where the speed is higher, in particular during the landing phase. The maximum authorized counterthrust speed corresponds for example to 50% of the maximum authorized counterthrust speed at speeds higher than the reference speed, this percentage being nevertheless able to vary according to the identified taxiing speed.

[0088] This control specific to the invention is shown diagrammatically on the double graph of [Fig.6], by the solid line curve 154 at the top for what concerns the engine speed, and by the solid line curve 156 at the bottom for what concerns the opening of the reverser.

[0089] In the control logic, it is provided that the braking force caused by the counter-thrust flow 50b can be added to the braking force caused on the wheels of the aircraft, via the dedicated pedals 124, shown in [Fig. 2]. But preferably, it could be provided that during the implementation of any action among the aforementioned actions A4 to A8, the actuation of at least one of the pedals 124 is considered as a request for emergency braking by the operator. Also, following the detection of such braking at a step E5, the system 120 implements, possibly in addition to the wheel braking, an action A9 consisting of ordering the thrust reverser to increase its opening if this is still possible, and / or to increase the engine speed if this is still possible.Therefore, in this emergency situation, the reverser opening level and / or engine speed will no longer correspond to those directly associated with the throttle position 122 to . within its module.

[0090] The triggering of action A9 may nevertheless be conditioned by the detection of a particular action on one and / or the other of the two pedals 124, such as exceeding a certain pedal travel, and / or the detection of a high pedal movement speed, following the action of the operator's foot.

[0091] Finally, it is noted that whatever the action performed among actions A3, A4 and A6 to A9, it is the same flow redirection members which are used within the inverter 30, namely the gates 29, which does not complicate the design of this inverter.

[0092] In the preferred embodiment which has just been described, it is the same throttle lever 122 which is used for the control of all the phases of the aircraft, whether in flight, on landing, on taxiing, etc. In particular, it therefore allows the specific control of the taxiing phase below the reference speed, but also the control of the engine speed in flight, as well as the control of the thrust reverser on landing.

[0093] According to an alternative partially shown in [Fig.9], the control system additionally comprises a main throttle lever 122 within a main module 110A, also connected to the engine regulation system 128. The main throttle lever 122 is here used for controlling the engine speed in flight, as well as for controlling the thrust reverser on landing, and more generally for all phases of the aircraft other than that of taxiing at a speed less than or equal to the reference speed.

[0094] The control system 120 is then configured so that the throttle 122 has authority over the main throttle 122A, as soon as the taxiing speed of the aircraft is less than or equal to the reference speed.

[0095] [Fig. 10] represents a propulsion unit 1 equipped with a reverser 30 according to another configuration, here comprising thrust reverser grids 32. The grids 32 comprise, in a conventional manner, fins making it possible to redirect the flow forward. Still in a known and conventional manner, the movement of the movable reverser cowls 33 allows at least part of the secondary flow to be redirected forward, to form the counterthrust flow 50b, thanks to the aforementioned fins. This type of reverser with grids, movable or fixed, proves to be perfectly compatible with the principle of the invention set out above, as indeed are all existing types of reversers, capable of being partially opened.

[0096] Furthermore, it is noted that on the joystick module 110, there are usually as many adjacent joysticks 122 as there are engines equipping the aircraft, respectively dedicated to the control of the propulsion units 1 arranged on one and the other of the two wings. These joysticks 122 can be moved simultaneously and identically by the operator, when controlling straight-line taxiing. A differential movement of these two throttle levers 122 leads, in the reversal control zone 144, to providing different braking counter-thrust forces for the propulsion units 1. Advantageously, this makes it possible, for example, to make turns at a particularly low speed, using the braking principle specific to the invention, by implementing a partial opening of the thrust reversers.

[0097] Various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples, and the scope of which is defined by the appended claims. Moreover, it is noted that in all the figures which have been described above, the elements which bear the same numerical references correspond to identical or similar elements.

[0098] Among the alternatives considered, the triggering of the partial opening of the reverser could be carried out by a control member other than the throttle lever, for example by one and / or the other of the brake pedals.

Claims

Claims

1. System (120) for controlling a propulsion unit (1) for an aircraft, the propulsion unit having a longitudinal central axis (Al) and comprising a turbomachine (2) configured to generate a direct thrust flow (50a), as well as a thrust reverser (30) configured to adopt: - a closed configuration in which the thrust reverser is inactive; and - an open configuration in which the thrust reverser is active, the open configuration allowing the reverser (30) to deflect at least a portion of a flow passing through the turbomachine, in order to form a counterthrust flow (50b) escaping from the propulsion unit with an axial direction opposite to that of the direct thrust flow (50a), the control system comprising at least one control member (122, 124) actuable by an operator, characterized in that the control system is configured so that when the taxiing speed of the aircraft is less than or equal to a reference speed, the control member (122, 124) can be moved into a position in which the control system orders the thrust reverser (30) to occupy a partial opening configuration between the closed configuration and the open configuration, so as to generate a counterthrust flow of intensity (50b) lower than that generated in the open configuration.

2. Control system according to claim 1, characterized in that the control member is a throttle lever (122) capable of being placed in an engine idle position (140b), and moved in a first direction (S1) from this engine idle position, towards a full throttle position (140a), and moved in a second direction (S2) still from this engine idle position (140b), in a thrust reversal control zone (144), towards a maximum counterthrust position (140d), and in that the control system is configured so that when the taxiing speed of the aircraft is less than or equal to the reference speed, the throttle lever (122) can be moved within the thrust reversal control zone (144) into at least one intermediate counterthrust position in which the control system orders the thrust reverser to occupy said configuration partial opening.

3. Control system according to claim 2, characterized in that it is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle lever (122) is placed in the engine idle position (140b), the control system orders the thrust reverser (30) to occupy a minimum partial opening configuration, so as to generate the counterthrust flow (50b) with a minimum intensity, preferably corresponding to the intensity of the direct thrust flow (50a) escaping from the turbomachine (2), so that the propulsion unit (1) generates zero or substantially zero thrust.

4. Control system according to claim 3, characterized in that it is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle lever (122) occupies any first intermediate position within a first part (114a) of the reversal control zone (144) located between the engine idle position (140b), and an intermediate reference position (140c), the control system orders the thrust reverser (30) to occupy a partial opening configuration, the opening level of which is a function of the first intermediate position within the first part (144a) of the reversal control zone (144), so as to generate the counterthrust flow (50b) with an intensity greater than that of the direct thrust flow (50a) escaping from the turbomachine, so that the propulsion unit (1) generates a counterthrust (160),preferably while maintaining the idle speed.,

5. Control system according to claim 4, characterized in that in the intermediate reference position of the throttle lever (122), the control system orders the thrust reverser (30) to occupy a maximum rolling opening configuration, corresponding to a maximum partial opening configuration of the reverser, or to its open configuration.

6. Control system according to claim 5, characterized in that it is configured so that when the taxiing speed of the aircraft is less than or equal to said reference speed and the throttle lever (122) occupies any second intermediate position within a second part (144b) of the reversing control zone (144) located between the reference intermediate position (140c), and the position maximum counterthrust (140d), the control system orders the thrust reverser (30) to maintain its maximum rolling opening configuration, and orders the application of an engine speed which is a function of the second intermediate position within the second part (144b) of the reversal control zone (144), so as to generate the counterthrust flow (50b) with an intensity greater than that of the direct thrust flow (50a) escaping from the turbomachine, so that the propulsion unit generates a counterthrust (160).

7. Control system according to any one of claims 2 to 6, characterized in that said throttle lever (122) is also used for controlling the engine speed in flight, as well as for controlling the thrust reverser (30) on landing.

8. Control system according to any one of the preceding claims, characterized in that it further comprises: - an engine control system (128) connected to the control member (122, 124) so that the position of the latter is transmitted to the control system (128), the latter being configured to deliver opening / closing instructions to the thrust reverser (30), as well as to deliver engine speed instructions to the turbomachine (2) - a processing unit (130) connected to the engine control system (128), the processing unit (130) being configured to receive information relating to the taxiing speed of the aircraft, and to transmit this information to the engine control system (128).

9. Method for controlling a propulsion unit (1) for an aircraft using a control system (120) according to any one of the preceding claims, characterized in that when the taxiing speed of the aircraft is less than or equal to said reference speed, the thrust reverser (30) is ordered, in response to the placement of the control member (122, 124) in a given position, to occupy a partial opening configuration between the closed configuration and the open configuration, so as to generate a counterthrust flow (50b) of lower intensity than that generated in the open configuration.

10. Aircraft (100) comprising at least one propulsion unit (1) as well as a control system (120) for this unit, according to any one of claims 1 to 8, the propulsion unit (1) comprising a turbomachine (2) configured to generate a flow of direct thrust (50a), as well as a thrust reverser (30) configured to adopt: - a closed configuration in which the thrust reverser is inactive; and - an open configuration in which the thrust reverser is active, the open configuration allowing the reverser (30) to deflect at least part of a flow passing through the turbomachine, in order to form a counter-thrust flow (50b) escaping from the propulsion unit (1) with an axial direction opposite to that of the direct thrust flow (50a).

11. Aircraft according to claim 10, characterized in that the thrust reverser (30) of the propulsion unit comprises flow redirection members (29, 32) for generating the counterthrust flow (50b), the control member being a throttle lever (122), and in that the reverser (30) is designed so that these same flow redirection members (29, 32) are used both when the lever (122) is placed in a position in which the control system (120) orders the thrust reverser (30) to occupy a partial opening configuration between the closed configuration and the open configuration, and when this lever (122) is placed in a maximum counterthrust position (140d).

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