Method for limiting the vibrations induced by brakes provided on aircraft landing gear wheels

Abstract

The invention relates to a method for limiting the vibrations induced by the friction from discs (2a, 2b) of brakes (1) of two braked wheels (R1.1, R1.2, R2.1, R2.2; R1.1',... R1.4', R2.1',... R2.4'; R1.1'',... R1.6'', R2.1'',... R2.6'') rotatably mounted on an axle of a landing gear (L1, L2; L1', L2'; L1'', L2'') of an aircraft (A; A'; A''), the method comprising, when the aircraft is taxiing at a speed (V; V'; V'') below a predetermined speed and when a pilot of the aircraft actuates the brake of the wheels of the landing gear, the following steps: − acquiring a temperature (T1.1, T1.2, T2.1, T2.2; T1.1',... T1.4', T2.1',... T2.4'; T1.1'',... T1.6'', T2.1'',... T2.6'') of the brake discs of each of the two wheels; − determining, from the acquired temperatures, the wheel whose brake is the least likely to induce vibrations; − activating the brake that is the least likely to induce vibrations.

Description

[0001]METHOD FOR LIMITING VIBRATIONS INDUCED BY BRAKES EQUIPMENT ON AIRCRAFT LANDING GEAR WHEELS The present invention relates to the field of aeronautics and more particularly to vibrations induced by brakes equipping aircraft wheels. BACKGROUND OF THE INVENTION An aircraft landing gear generally comprises a leg having a first end connected to a structure of the aircraft and a second end provided with a shaft or axle on which a wheel is mounted to pivot. The wheel comprises a rim connected by a web to a hub which receives the shaft of the leg and defines with the rim a space in which is arranged a stack of discs comprising alternating stator discs fixed relative to the shaft and rotor discs fixed relative to the rim. The discs are generally made of carbon-carbon material.An actuator, for example a hydraulic or electric cylinder, is arranged to exert a pressing force on the stack of discs via a hydraulic crown. The rim comprises two annular edges or beads between which a tire is mounted. Each braking action carried out by the pilot of an aircraft causes friction of the discs resulting in an instantaneous increase in the temperature of said discs but also the appearance of vibrations whose intensity depends in particular on the pressing force, the temperature of the discs and the rotation speed of the wheel. These vibrations tend to propagate through the landing gear and mechanically stress the structure of the aircraft, which can affect passenger comfort but also damage the structure and therefore compromise the safety of the aircraft. Furthermore, climate change is a major concern for many legislative and regulatory bodies around the world.Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new aircraft types and those currently in operation, requiring the implementation of technological solutions to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change. Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. All stakeholders in the sector are constantly working to improve energy efficiency.The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of air transport. Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible to reduce the environmental footprint of its activity.This sustained research and development work relates to new generations of aircraft engines, the lightening of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, essential complements to technological progress, aeronautical biofuels. OBJECT OF THE INVENTION The invention results from this work and aims to propose a method for limiting the vibrations induced by the brakes fitted to aircraft landing gear wheels. SUMMARY OF THE INVENTION To this end, a method is provided for limiting the vibrations induced by the friction of brake discs of two braked wheels mounted for rotation on an axle of an aircraft landing gear.According to the invention, the method comprises, when the aircraft is rolling at a speed less than or equal to a predetermined speed and a pilot of said aircraft actuates the brake of the wheels of the landing gear, the following steps: − acquisition of a temperature of the brake discs of each of the two wheels; − determination, from the acquired temperatures, of the wheel whose brake has the lowest probability of inducing vibrations; and − activation of the brake having the lowest probability of inducing vibrations. Such a method makes it possible, in particular during taxiing phases which do not require the use of the brakes of the two wheels, to brake only one of the two wheels and to use the brake least subject to vibrations so as to limit their propagation in the landing gear. On the other hand, when the speed is equal to or greater than the predetermined speed, the brakes of all the wheels are activated.According to a particular characteristic, the wheel whose brake has the lowest probability of inducing vibrations is further determined from at least one of the following parameters: the speed at which the aircraft is traveling, the speed at which the wheels rotate, the material from which the brake discs are made, and the desired intensity of friction of the discs. In particular, the wheel whose brake has the lowest probability of inducing vibrations is determined from charts or equations linking, for a given intensity of friction of the discs and a given speed of rotation of the wheel, the temperature of the brake 1 of said wheel to the probability of inducing vibrations. According to a particular characteristic, the predetermined speed is between 15 knots and 25 knots. In particular, the predetermined speed is equal to 20 knots.The invention also relates to an aircraft comprising: − a first main landing gear and a second main landing gear each comprising at least one axle provided with two wheels, each of the wheels being equipped with a brake comprising brake discs, − an electronic brake control unit connected to wheel brake temperature sensors, and receiving a signal representative of a forward speed of the aircraft, the electronic control unit being arranged to implement such a method. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood in the light of the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the appended drawings, among which: [Fig. 1] Figure 1 is a front view of an aircraft comprising main landing gear each provided with two braked wheels; [Fig. 2] Figure 2 is a bottom view of the aircraft illustrated in Figure 1; [Fig.3] Figure 3 is an axial sectional view of one of the braked wheels of the aircraft illustrated in Figure 1; [Fig.4] Figure 4 is a view illustrating an example of charts used to determine, according to the method of the invention, the probability that the brakes of the wheels of the aircraft illustrated in Figure 1 induce vibrations as a function of the temperature of said brakes; [Fig.5] Figure 5 represents the braked wheels of the aircraft illustrated in Figure 1; [Fig.6] Figure 6 is a flowchart illustrating a method for limiting the vibrations induced by the brakes of the braked wheels of the aircraft illustrated in Figure 5, according to a particular embodiment of the invention; [Fig.7A] Figure 7A is a view similar to Figure 2, illustrating a first variant of the main landing gear of the aircraft illustrated in Figure 1; [Fig.7B] Figure 7B is analogous to Figure 5, illustrating the braked wheels of the aircraft illustrated in Figure 7A; [Fig.[Fig. 7C] Figure 7C is a flowchart illustrating a method for limiting the vibrations induced by the brakes of the braked wheels of the aircraft illustrated in Figure 7B, according to a particular embodiment of the invention; [Fig. 8A] Figure 8A is a view similar to Figure 2, illustrating a second variant of the main landing gear of the aircraft illustrated in Figure 1; [Fig. 8B] Figure 8B is similar to Figure 5, illustrating the braked wheels of the aircraft illustrated in Figure 8A; [Fig. 8C] Figure 8C is a flowchart illustrating a method for limiting the vibrations induced by the brakes of the braked wheels of the aircraft illustrated in Figure 8B, according to a particular embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION With reference to Figures 1 and 2, the invention is described in application to an aircraft A comprising a first main landing gear L1 and a second main landing gear L2.The first landing gear L1 and the second landing gear L2 are arranged respectively to the right and left of a median longitudinal plane of the aircraft A. The terms "right" and "left" are to be understood with reference to a usual direction of advance of the aircraft A (i.e. forward). The arrow F to the left in Figure 2 indicates the usual direction of advance of the aircraft A. The first landing gear L1 and the second landing gear L2 are here of the retractable type but the invention is applicable to fixed landing gears. The first landing gear L1 and the second landing gear L2 each comprise a leg J ​​having a first end articulated on a structure of the aircraft A and, opposite, a second end carrying an axle E. Each axle E is provided with two wheels R1.1, R1.2, R2.1, R2.2 each comprising a rim which is connected by a web to a hub mounted to rotate on the axle E about an axis X by means of bearings.The rim here comprises two half-rims which are assembled by bolts and which each comprise a bead in such a way that a tire can be trapped between the beads. The wheels R1.1, R1.2, R2.1, R2.2 of the first and second landing gears L1, L2 are said to be "braked", that is to say equipped with a brake 1 intended to slow down or even stop the aircraft A when it is on the ground. The following description relates to one of the wheels R1.1, R1.2, R2.1, R2.2. The wheels R1.1, R1.2, R2.1, R2.2 are here identical but can also be different. With reference to Figure 3, the brake 1 of the wheel R1.1, R1.2, R2.1, R2.2 comprises, in a manner known per se, stator discs 2a and rotor discs 2b which are stacked alternately against each other on a torque tube 3 fixed to a collar of the axle E.The stator discs 2a and the rotor discs 2b form a stack of friction discs extending inside an annular space delimited by the wheel R1.1, R1.2, R2.1, R2.2. The stator discs 2a comprise axial peripheral notches each receiving a section of a tenon which is attached to an outer surface of the torque tube 3 to ensure rotational coupling of the stator discs 2a with the torque tube 3 around the axis X. The rotor discs 2b comprise axial peripheral notches each receiving a section of a bar which is attached to an inner surface of the rim of the wheel R1.1, R1.2, R2.1, R2.2 to ensure rotational coupling of the rotor discs 2b with said wheel R1.1, R1.2, R2.1, R2.2 around the axis X. The stator discs 2a and the rotor discs 2b are here made of a carbon-carbon composite material.The brake 1 also comprises actuators 4 (here six in number) which are controlled by an electronic braking control unit U of the aircraft A and which are carried by an actuator-carrying ring 5 fixed to one end of the torque tube 3. The actuators 4 are here hydraulic and have central axes, parallel to each other, inscribed on the same circle whose center is located on the axis X of rotation of the wheel R1.1, R1.2, R2.1, R2.2. Each of the actuators 4 comprises a piston 4.1 received in a cylindrical cavity 5.1 of the actuator-carrying ring 5. The cavities 5.1 are distributed equally around the axis X of rotation of the wheel R1.1, R1.2, R2.1, R2.2. The pistons 4.1 are movable in translation along an axis parallel to the X axis of rotation of the wheel R1.1, R1.2, R2.1, R2.2 so as to exert a sufficient pressing force on the stack of discs 2a, 2b to force all of the stator discs 2a and rotor discs 2b to rub against each other and thus generate a braking torque on the rotor discs 2b. The friction of the stator discs 2a and the rotor discs 2b causes an instantaneous increase in the temperature of said stator discs 2a and said rotor discs 2b, but also vibrations whose intensity depends in particular on: − the pressing force exerted by the actuators 4; − the temperature of the stack of discs 2a, 2b; − the rotation speed of the wheel R1.1, R1.2, R2.1, R2.2 around the axis X; and − the material from which the stator discs 2a and the rotor discs 2b are made. Part of the kinetic energy of aircraft A is thus dissipated as heat. Wheel R1.1, R1.2, R2.1, R2.2 is equipped with a heat shield 6 interposed between the inner surface of the rim and the stack of discs 2a, 2b to protect the rim and the tire carried by said rim from this influx of heat. The heat shield 6 extends axially projecting from the rim and is here made up of several very thin metal sheets separated by a thin air gap. The wheel is also equipped with a tachometer (not shown) delivering a signal representative of a rotation speed of the wheel R1.1, R1.2, R2.1, R2.2 around the axis X to the electronic control unit U of the aircraft A. All this is well known and is recalled only to situate the invention. The brake 1 also comprises a temperature sensor 7 arranged to deliver a signal representative of a temperature T1.1, T1.2, T2.1, T2.2 of the stack of discs 2a, 2b of the wheel R1.1, R1.2, R2.1, R2.2 to the electronic control unit U of the aircraft A.The temperature sensor 7 is here a non-contact temperature probe comprising an infrared thermocouple but can also be of other types: RTD (Resistance Temperature Detector), thermistors, etc. The connection between the temperature sensor 7 and the electronic control unit U can be wired or wireless. As illustrated in Figure 3, four different positions P1, P2, P3, P4 of the temperature sensor 7 are envisaged here. The temperature sensor 7 is arranged: - on the actuator-carrying ring 5 of the brake 1, the temperature sensor 7 extending between two neighboring actuators 4 along an axis parallel to the axis X of rotation of the wheel R1.1, R1.2, R2.1, R2.2, projecting from a front surface of the actuator-carrying ring 5 and opposite the first stator disc 2a of the stack of discs (position P1); or - on the rim or heat shield 6 of the wheel R1.1, R1.2, R2.1, R2.2, the temperature sensor 7 extending radially projecting from an inner surface of the rim or the heat shield 6, facing the first stator disc 2a (positions P2.1 and P2.2); or - on the rim or in the heat shield 6 of the wheel R1.1, R1.2, R2.1, R2.2, the temperature sensor 7 extending radially projecting from an inner surface of the rim or the heat shield 6, facing one of the stator discs 2a of the stack of discs, with the exception of the first stator disc 2a (position P3); or - on the torque tube 3, the temperature sensor 7 extending radially projecting from an outer surface of the torque tube 3, facing one of the rotor discs 2b of the stack of discs (position P4). The temperature sensor 7 and the stack of discs 2a, 2b are separated by a sufficient distance to protect said temperature sensor 7 from the heat released by the brake 1 while ensuring a direct and precise reading of the temperature T1.1, T1.2, T2.1, T2.2 of the stack of disks 2a, 2b with little latency. The temperature sensor 7 may be equipped with a shield arranged to protect said temperature sensor 7 from the heat released by the brake 1, and / or a deflector arranged to protect said temperature sensor 7 from dust and braking residues. The electronic control unit U is connected to a rudder bar comprising a first right pedal P1 and a second left pedal P2 moved independently of each other by the feet of the pilot of the aircraft A. The first pedal P1 makes it possible to control, via the electronic control unit U, the brakes 1 of the wheels R1.1, R1.2 of the first landing gear L1 (independently of those of the second landing gear L2). The second pedal P2 allows the brakes 1 of the wheels R2.1, R2.2 of the second landing gear L2 to be controlled via the electronic control unit U (independently of those of the first landing gear L1).The first pedal P1 and the second pedal P2 are each equipped with a displacement sensor delivering respectively, to the electronic control unit U, a signal representative of an angular position of said first pedal P1 and said second pedal P2. The pressing force exerted on the stack of discs 2a, 2b of the wheels R1.1, R1.2 of the first landing gear L1 and of the wheels R2.1, R2.2 of the second landing gear L2 is linked respectively to the angular positions of the first pedal P1 and of the second pedal P2. The electronic control unit U is also arranged to receive a signal representative of a forward speed V of the aircraft A (for example delivered by an inertial unit or an on-board GPS) or at the very least to estimate the forward speed V of the aircraft A from several signals (for example those delivered by the tachometers measuring the rotation speeds of the wheels R1.1, R1.2, R2.1, R2.2 around the axis X).In order to improve passenger comfort and to avoid any damage to the structure that could affect the safety of the aircraft A, the electronic control unit U is arranged to implement a method for limiting the vibrations induced by the friction of the stator discs 2a and the rotor discs 2b generated by the use of the brakes 1, in particular during the taxiing phases. With reference to Figure 6, the different steps of the method will now be detailed. When the speed V of the aircraft A is less than or equal to a predetermined speed here equal to 20 knots, and the pilot presses the first pedal P1, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T1.1, T1.2 of the brakes 1 of the wheels R1.1, R1.2 of the first landing gear L1, then determines among said brakes 1 which one has the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A. Similarly, when the speed V of the aircraft A is less than or equal to the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T2.1, T2.2 of the brakes 1 of the wheels R2.1, R2.2 of the second landing gear L2, then determines among said brakes 1 which one has the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A. The determination of the probability of inducing vibrations can be carried out from predefined charts or equations (or more advanced models) and memorized by the electronic control unit U.Figure 4 illustrates an example of charts used by the electronic control unit U to determine the probability that the brake 1 induces vibrations. This example links, for a given press force and rotational speed of the wheel R1.1, R1.2, R2.1, R2.2, the temperature T1.1, T1.2, T2.1, T2.2 of the brake 1 of said wheel R1.1, R1.2, R2.1, R2.2 to the probability of inducing vibrations.The probability of inducing vibrations evolves here as follows: − between 0 and 65°C (degrees Celsius), the probability is substantially zero; − between 65°C and 150°C, the probability increases substantially linearly until it reaches 100%; − between 150°C and 260°C, the probability decreases substantially linearly until it falls back to 0%; − between 260 and 400°C, the probability is substantially zero; − between 400°C and 475°C, the probability increases substantially linearly again until it reaches 30%; and − between 475°C and 500°C, the probability decreases substantially linearly again until it falls back to 0%. The desired pressing force and the temperature T1.1, T1.2, T2.1, T2.2 can be determined by the electronic control unit U via the pedal displacement sensor and the temperature sensor 7 considered respectively. In the example shown in Figure 5: - the temperature T1.1 of brake 1 of wheel R1.1 is equal to 150°C; - the temperature T1.2 of brake 1 of wheel R1.2 is equal to 95°C; - the temperature T2.1 of brake 1 of wheel R2.1 is equal to 100°C; and - the temperature T2.2 of brake 1 of wheel R2.2 is equal to 98°C. Therefore, when the speed V of aircraft A is less than or equal to the predetermined speed and the pilot presses the first pedal P1, the electronic control unit U activates brake 1 of wheel R1.2 and not that of wheel R1.1: the probability that brake 1 of wheel R1.2 induces vibrations is lower than that of brake 1 of wheel R1.1. Similarly, when the speed V of aircraft A is less than or equal to the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U activates brake 1 of wheel R2.2 and not that of wheel R2.1: the probability that brake 1 of wheel R2.2 induces vibrations is lower than that of brake 1 of wheel R2.1.It is understood that when the speed V of the aircraft A is less than or equal to the predetermined speed and the pilot simultaneously presses the first pedal P1 and the second pedal P2, the electronic control unit U simultaneously activates the brakes 1 of the wheels R1.2, R2.2 and not those of the wheels R1.1, R2.1: the entirety of the brakes 1 is thus not used when the speed V of the aircraft A is less than or equal to the predetermined speed, which makes it possible to significantly improve the longevity of the stator discs 2a and the rotor discs 2b of the brakes 1 of the aircraft A, but also to limit the vibrations induced by the brakes 1. Figures 7A and 7B illustrate an aircraft A' which is none other than a first variant of the aircraft A.Aircraft A' differs from aircraft A in that it comprises a first main landing gear L1' and a second main landing gear L2', each comprising a first axle E1' and a second axle E2', each axle E1', E2' carrying two wheels R1.1', R1.2', R1.3', R1.4', R2.1', R2.2', R2.3', R2.4'. The wheels R1.1', … R1.4', R2.1', … R2.4' are, as for aircraft A, equipped with a brake 1 to slow down or even stop aircraft A' when it is on the ground. The brake 1 comprises a temperature sensor 7 arranged to deliver a signal representative of a temperature T1.1', T1.2', T1.3', T1.4', T2.1', T2.2', T2.3', T2.4' of the stack of discs 2a, 2b of the wheel R1.1', … R1.4', R2.1', … R2.4' to the electronic braking control unit U of the aircraft A'. The electronic control unit U is also arranged to receive a signal representative of a forward speed V' of the aircraft A'.With reference to Figure 7C, when the speed V' of the aircraft A' is less than or equal to a predetermined speed here equal to 20 knots, and the pilot presses the first pedal P1, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T1.1', … T1.4' of the brakes 1 of the wheels R1.1', … R1.4' of the first landing gear L1', then determines for each axle E1', E2' the brake 1 having the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A'. Similarly, when the speed V' of the aircraft A' is less than or equal to the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T2.1', … T2.4' of the brakes 1 of the wheels R2.1', … R2.4' of the second landing gear L2', then determines for each axle E1', E2' the brake 1 having the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A'. In the example illustrated in figure 7B: - the temperature T1.1' of the brake 1 of the wheel R1.1' is equal to 85°C; - the temperature T1.2' of the brake 1 of the wheel R1.2' is equal to 100°C; - the temperature T1.3' of the brake 1 of the wheel R1.3' is equal to 475°C; - the temperature T1.4' of the brake 1 of the wheel R1.4' is equal to 200°C; - the temperature T2.1' of the brake 1 of the wheel R2.1' is equal to 175°C; - the temperature T2.2' of brake 1 of wheel R2.2' is equal to 250°C; - the temperature T2.3' of brake 1 of wheel R2.3' is equal to 150°C; and - the temperature T2.4' of brake 1 of wheel R2.4' is equal to 400°C.Therefore, when the speed V' of the aircraft A' is less than or equal to the predetermined speed and the pilot presses the first pedal P1, the electronic control unit U activates the brake 1 of the wheels R1.1', R1.3', and not those of the wheels R1.2', R1.4'. Similarly, when the speed V' of the aircraft A' is less than or equal to the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U activates the brake 1 of the wheels R2.2', R2.4', and not those of the wheels R2.1', R2.3'. It is understood that when the speed V' of the aircraft A' is less than or equal to the predetermined speed and the pilot simultaneously presses the first pedal P1 and the second pedal P2, the electronic control unit U simultaneously activates the brakes 1 of the wheels R1.1', R1.3', R2.2', R2.4' and not those of the wheels R1.2', R1.4', R2.1', R2.3': the entirety of the brakes 1 is thus not used when the speed V' of the aircraft A' is less than or equal to the predetermined speed, which makes it possible to significantly improve the longevity of the stator disks 2a and the rotor disks 2b of the brakes 1 of the aircraft A', but also to limit the vibrations induced by the brakes 1. Figures 8A and 8B illustrate an aircraft A'' which is none other than a second variant of the aircraft A. The aircraft A'' differs from the aircraft A in that it comprises a first main landing gear L1'' and a second main landing gear L2'' each comprising a first axle E1'', a second axle E2'' and a third axle E3''. Each axle E1'', E2'', E3'' carries two wheels. R1.2'', R1.3'', R1.4'', R1.5'', R1.6'', R2.1'', R2.2'', R2.3'', R2.4'', R2.5'', R2.6''. The wheels R1.1'', … R1.6'', R2.1'', … R2.6'' are, as for aircraft A, equipped with a brake 1 to slow down or even stop aircraft A'' when it is on the ground. The brake 1 comprises a temperature sensor 7 arranged to deliver a signal representative of a temperature T1.1'', T1.2'', T1.3'', T1.4'', T1.5'', T1.6'', T2.1'', T2.2'', T2.3'', T2.4'', T2.5'', T2.6'' of the stack of discs 2a, 2b of the wheels R1.1'', … R1.6'', R2.1'', … R2.6'' to the electronic braking control unit U of the aircraft A''. The electronic control unit U is also arranged to receive a signal representative of a forward speed V'' of the aircraft A''.With reference to Figure 8C, when the speed V'' of the aircraft A'' is less than or equal to a predetermined speed here equal to 20 knots, and the pilot presses the first pedal P1, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T1.1'', … T1.6'' of the brakes 1 of the wheels R1.1'', … R1.6'' of the first landing gear L1'', then determines for each axle E1'', E2'', E3'' the brake 1 having the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A''. Similarly, when the speed V'' of the aircraft A'' is less than or equal to the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U first proceeds, via the temperature sensors 7, to acquire the temperatures T2.1'', … T2.6'' of the brakes 1 of the wheels R2.1'', … R2.6'' of the second landing gear L2'', then determines for each axle E1'', E2'', E3'' the brake 1 having the lowest probability of inducing vibrations and then proceeds to activate it to slow down the aircraft A''. In the example illustrated in figure 8B: - the temperature T1.1'' of the brake 1 of the wheel R1.1'' is equal to 80°C; - the temperature T1.2' of the brake 1 of the wheel R1.2'' is equal to 82°C; - the temperature T1.3'' of the brake 1 of the wheel R1.3'' is equal to 85°C; - the temperature T1.4'' of the brake 1 of the wheel R1.4'' is equal to 100°C; - the temperature T1.5'' of the brake 1 of the wheel R1.5'' is equal to 475°C; - the temperature T1.6'' of brake 1 of wheel R1.6'' is equal to 200°C; - the temperature T2.1'' of brake 1 of wheel R2.1'' is equal to 120°C; - the temperature T2.2'' of brake 1 of wheel R2.2'' is equal to 230°C; - the temperature T2.3'' of brake 1 of wheel R2.3'' is equal to 175°C; - the temperature T2.4'' of brake 1 of wheel R2.4'' is equal to 250°C; - the temperature T2.5'' of brake 1 of wheel R2.5'' is equal to 150°C; and - the temperature T2.6'' of brake 1 of wheel R2.6'' is equal to 400°C. Therefore, when the speed V'' of aircraft A'' is lower than the predetermined speed and the pilot presses the first pedal P1, the electronic control unit U activates brake 1 of wheels R1.1'', R1.3'', R1.5'' and not those of wheels R1.2'', R1.4'', R1.6''. Similarly, when the speed V'' of the aircraft A'' is lower than the predetermined speed and the pilot presses the second pedal P2, the electronic control unit U activates the brake 1 of the wheels R2.2'', R2.4'', R2.6'' and not those of the wheels R2.1'', R2.3'', R2.5''. It is understood that when the speed V'' of the aircraft A'' is lower than the predetermined speed and the pilot presses simultaneously the first pedal P1 and the second pedal P2, the electronic control unit U simultaneously activates the brakes 1 of the wheels R1.1'', R1.3'', R1.5'', R2.2'', R2.4'', R2.6'' and not those of the wheels R1.2'', R1.4'', R1.6'', R2.1'', R2.3'', R2.5'': the entirety of the brakes 1 is thus not used when the speed V'' of the aircraft A'' is lower than the predetermined speed, which makes it possible to significantly improve the longevity of the stator discs 2a and the rotor discs 2b of the brakes 1 of the aircraft A'', but also to limit the vibrations induced by the brakes 1. Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims. Although here the method of the invention is applied here to the two axles E1', E2' of the landing gears L1', L2' of the aircraft A', it can be applied to only one of the two axles E1', E2'.Although here the method of the invention is applied here to the three axles E1'', E2'', E3'' of the landing gears L1'', L2'' of the aircraft A'', it can be applied to only one or two of the axles E1'', E2'', E3''. Although the actuators 4 are hydraulic here, they can be electric, pneumatic, etc. Although the stator discs 2a and the rotor discs 2b are here made of a carbon-carbon composite material, they can be made of another material. The number of charts can be increased, for example by taking into account other parameters (material of the stator discs 2a and rotor discs 2b, use of thrust reversal or "reverse", activation of automatic braking or "autobrake", use of brake cooling fans 1, etc.). Although the predetermined speed here is equal to 20 knots, it can be different and for example be between 15 and 25 knots.

Claims

CLAIMS 1. Method for limiting vibrations induced by the friction of discs (2a, 2b) of brakes (1) of two wheels (R 1.1 , R 1.2 , R 2.1 , R 2.2 ; R 1.1 ', … R 1.4 ', R 2.1 ', … R 2.4 ' ; R 1.1 '', … R 1.6 '', R 2.1 '', … R 2.6 '') braked wheels mounted for rotation on an axle of a landing gear (L1, L2; L1', L2'; L1'', L2'') of an aircraft (A; A'; A''), the method comprising, when the aircraft is rolling at a speed (V; V'; V'') less than or equal to a predetermined speed and a pilot of said aircraft actuates the brake of the wheels of the landing gear, the following steps: − acquisition of a temperature (T 1.1 , T 1.2 , T 2.1 , T 2.2 ; T 1.1 ', … T 1.4 ', T 2.1 ', … T 2.4 ' ; T 1.1 '', … T 1.6 '', T 2.1 '', … T 2.6'') of the brake discs of each of the two wheels; − determination, from the acquired temperatures, of the wheel whose brake has the lowest probability of inducing vibrations; − activation of the brake having the lowest probability of inducing vibrations.

2. Method according to claim 1, in which the wheel (R 1.1 , R 1.2 , R 2.1 , R 2.2 ; R 1.1 ', … R 1.4 ', R 2.1 ', … R 2.4 ' ; R 1.1 '', … R 1.6 '', R 2.1 '', … R 2.6'') whose brake (1) has the lowest probability of inducing vibrations is further determined from at least one of the following parameters: the speed (V; V'; V'') at which the aircraft is traveling, the speed at which the wheels rotate, the material from which the brake discs (2a, 2b) are made, and the desired intensity of friction of the discs (2a, 2b).

3. Method according to claim 2, in which the wheel whose brake has the lowest probability of inducing vibrations is determined from charts or equations linking, for an intensity of friction of the discs (2a, 2b) and a rotation speed of the wheel R 1.1 , R 1.2 , R 2.1 , R 2.2 data, temperature (T 1.1 , T 1.2 , T 2.1 , T 2.2 ) of the brake (1) of said wheel (R 1.1 , R 1.2 , R 2.1 , R 2.2 ) to the probability of inducing vibrations.

4. Method according to any one of the preceding claims, wherein the predetermined speed is between 15 knots and 25 knots.

5. Method according to claim 4, wherein the predetermined speed is equal to 20 knots.

6. Aircraft (A; A'; A'') comprising: − a first main landing gear (L1; L1'; L1'') and a second main landing gear (L2; L2'; L2'') each comprising at least one axle (E; E1', E2'; E1'', E2'', E3'') provided with two wheels (R1.1, R1.2, R2.1, R2.2; R1.1', … R1.4', R2.1', … R2.4'; R1.1'', … R1.6'', R2.1'', … R2.6''), each of the wheels being equipped with a brake (1) comprising brake discs (2a, 2b), − an electronic control unit (U) for the brakes connected to temperature sensors (7) for the wheel brakes, and receiving a signal representative of a forward speed (V) of the aircraft, the electronic control unit (U) being arranged to implement the method according to any one of the preceding claims for each of the axles.

Images