CN112407259A - System for controlling the braking of an aircraft equipped with a thrust reversal system - Google Patents

Abstract

The invention relates to a method for controlling the braking of an aircraft equipped with an undercarriage having braking wheels, the aircraft being driven by a jet engine and equipped with a thrust reversal system, the method comprising estimating the grip/adhesion of the braking wheels on the basis of the estimated grip/adhesion and activating the counterthrust system or regulating the counterthrust generated by the counterthrust system (if the system has been activated).

Description

System for controlling the braking of an aircraft equipped with a thrust reversal system

Technical Field

The invention relates to a method and a system for braking an aircraft equipped with one or more turbojet engines and with a thrust reversal system.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Most aircraft comprise landing gear whose basic function consists, on the one hand, of absorbing most of the kinetic energy due to the vertical component of the speed of the aircraft when landing, and, on the other hand, of allowing the aircraft to move on the ground, in particular during the braking phase.

Aircraft braking systems include a brake actuator (hydraulic or electromechanical) that is controlled to apply a braking torque to the wheels of the aircraft to reduce the speed.

The control of the braking system typically includes a brake assist system, such as an anti-skid system or an automatic braking system (often referred to as an "autobrake" system).

An anti-skid system or anti-skid protection system allows the braking force applied to each braking wheel to be automatically adjusted to prevent any wheel from becoming blocked or slipping. For this purpose, each braked wheel is equipped with a rotation speed sensor, the data measured by these sensors allowing the detection of the slip of one or more wheels.

The automatic braking system allows to obtain automatically the deceleration of the aircraft, the necessary braking force being calculated and controlled by the system, in particular depending on the braking distance preselected by the pilot. When the automatic braking system is activated, the driver no longer needs to monitor the braking via the brake pedal (or rudder pedal).

When the aircraft is driven by turbojet engines, some or all of these turbojet engines are usually equipped with a thrust reverser system. The thrust reverser functions to improve the braking capacity of the aircraft during landing by advancing at least part of the thrust generated by the turbojet engine. At this stage, the thrust reverser directs at least part of the jet of the turbojet forward, generating a thrust reaction which is added to the braking of the wheels and of the airlock of the aircraft.

For a bypass turbojet engine that produces both a hot (primary) and a cold (secondary) air stream, the thrust reverser may act on both streams, or only on the cold stream.

In general, thrust reversers are devices subject to high mechanical stresses, which must meet strict specifications, in particular with respect to operational reliability. The design of the device therefore also has a corresponding negative impact on the quality and cost of the propulsion system.

Furthermore, when the reverse thrust system of the turbojet is activated, the reverse thrust will be more pronounced due to the higher engine speed. Thus, the use of thrust reversers typically occurs at higher motor speeds, such as around 75% of the maximum speed. In some cases, such as an emergency landing or a take-off disruption, the motor speed may be higher. This directly results in a large load on the motor, which affects its service life.

Disclosure of Invention

The invention relates to a control method which allows limiting the load on the thrust reverser, in particular in order to reduce the consumption and wear of the electric motor.

To this end, the invention provides a method for controlling the braking of an aircraft equipped with an undercarriage having a braking wheel, the aircraft being driven by a turbojet engine and equipped with a thrust reverser system, the method comprising the following steps:

evaluating the adhesion of the braked wheels, an

Based on the estimated adhesion, the thrust reverser system is activated, or the thrust reverser generated by the thrust reverser system is adjusted (if already activated).

Thus, by allowing automatic activation of the thrust reverser when poor adhesion conditions are detected, the method of the invention allows to keep using the thrust reverser in case of emergency or in case of polluting the track, while limiting the reaction time. In fact, the automatic activation of the thrust reverser does not depend on the reaction time of the pilot. This reduces the response time of the aircraft to an accident event, thereby improving the safety of the aircraft maneuvering on the ground. On the premise of not influencing landing safety, the fuel consumption, especially the abrasion of the motor is reduced.

In one form, the thrust reverser system is activated if the estimated adhesion is less than a predetermined threshold.

In another form, the adhesion is estimated based on the slip rate of the wheel.

In another form, the slip rate of the wheel is dependent upon a measure of the speed of rotation of the braked wheel.

The invention also relates to a braking control system for an aircraft equipped with a braked wheel and one or more turbojet engines equipped with a thrust reverser system, the system comprising: a processing unit capable of determining the slip rate of a wheel and capable of generating a signal representative of insufficient adhesion when the slip rate is greater than a predetermined threshold; and the control unit can receive the signal generated by the processing unit and control the start of the reverse thrust system after receiving the signal.

The system according to the invention thus allows the coupling of the braking system and the thrust reversal system of the aircraft. According to the invention, the system retrieves information relating to the braking quality and deduces therefrom the automatic actuation sequence of the thrust reverser if the braking is determined to be insufficient to meet the command given by the pilot or automatic braking.

In one form, the control unit is connected to a turbojet regulation system, or FADEC (full authority digital engine instructions).

In another form, the control unit is integrated into a regulation system of a turbojet engine (FADEC).

In another form, the slip rate of the wheel is dependent upon information returned by the wheel speed sensor.

The invention also relates to an aircraft equipped with a braked wheel and one or more turbojet engines equipped with a thrust reversal system, the aircraft being able to implement the above method and/or comprising the above system.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

For the purposes of promoting an understanding of the disclosure, various forms thereof will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagram showing components of a brake control system consistent with the present invention;

FIG. 2 is a simplified logic diagram of a thrust reversal function in an implementation of a system and/or method according to the present disclosure; and

FIG. 3 is a logic diagram of a landing procedure with or without a thrust reverser in the context of an implementation of a system and/or method according to the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

Detailed Description

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

FIG. 1 illustrates components of a brake control system consistent with the present invention. These components allow the implementation of the method according to the invention, in particular on a subset of aircraft, comprising at least one landing gear 1 and at least one turbojet nacelle 2 (only the rear part of which is shown).

The brake control system of an aircraft comprises a wheel 10 mounted on a landing gear 1, at least a portion of the wheel 20 being braked (that is to say equipped with brakes). Two wheels 10 shown in fig. 1 are braked and are provided with brakes 11 for this end. The brake 11 is electromechanical or hydraulic.

In the example, each braking wheel (two wheels 10) is also equipped with a rotation speed sensor 12. The sensor 12 is connected to an input 13A of a processing unit 13. Thus, the data measured by all the sensors 12 are transmitted to the processing unit 13. The processing unit 13 is able to detect the slipping of one or more braked wheels, in particular depending on the data returned by the rotation speed sensor 12. When the processing unit 13 detects one or more wheel slip, the latter generates a signal representative of the wheel slip or slip, which activates the anti-slip protection. The braking is therefore adjusted to limit or eliminate any slip of the wheels, according to the slip signal issued by the processing unit 13.

In the system of the present disclosure, the processing unit 13 comprises an output 13b connected to an input 14a of the control unit 14. The output 13b allows a copy of the sliding signal to be sent to the control unit 14 if required. Thus, when the processing unit 13 detects a slip of one or more wheels, the corresponding slip signal is transmitted directly to the control unit 14. The control unit 14 comprises an output 14b ("full authority digital engine control" or digital regulation calculator with full authority of the motor) directly connected to the motor regulation system 15 or to a first input 15a of the FADEC 15. The FADEC 15 also comprises a second input 15B connected to the output 16A of the throttle lever 16, this link allowing the transmission of information relating to the position of the throttle lever 16. The FADEC 15 comprises an output 15C which output 15C is connected to an input 20A of the control system 20 of the inverse thruster 21.

Therefore, with the above-described structure, when the processing unit 13 issues a slide signal, the control unit 14 receives the signal. From this signal, the control unit 14 determines the activation sequence or, if necessary, the modulation sequence of the thrust reverser 21. This command is transmitted to FADEC 15, FADEC 15 transmits it to control system 20 of thrust reverser 21. In the case where the processing unit 13 identifies the skid 20, the control unit 14 therefore replaces the action of the pilot on the throttle stick 16 and sends an activation command of the thrust reverser 21 to the FADEC 15. Thus, the reverse thrust system may be automatically activated when one or more wheels are detected to slip. Such automatic activation allows to trigger the thrust reverser urgently, in particular when the state of the track, in particular its adhesion, proves to be inferior to that expected and has a significant impact on the braking capacity of the aircraft. Automatic actuation allows valuable seconds to be saved relative to manual actuation, depending on pilot reaction time. Systems and methods according to the present invention allow for automatic activation when one or more wheels skid, thereby providing the required safety while encouraging the pilot to provide a landing without initiating thrust reversals. Conversely, if the braking conditions are correct, the counterthrust system is not executed. The invention therefore allows to reserve the use of the counterthrust system mainly in emergency situations, thus limiting the consumption, in particular the wear of the electric machine.

If the measured slip rate (of the braked wheels) is greater than a threshold value, the system will determine the automatic activation of the thrust reverser. The threshold value should take into account in particular the deformation of the mechanical or braking forces caused by partial or complete taxiing (resultant forces and moments of force on the aircraft). The torque can be calculated in real time based on the slip signal delivered by each wheel. Two factors will be specifically considered: stability of the path and lengthening of the path. In addition, the processing unit analyzes the distance traveled and the slip rate of the aircraft, as well as the lengthening of the path. This will lead to the system making deployment decisions, especially in the case of autobraking (autobraking), if excessive distortion with respect to the path instructions is observed.

As shown in fig. 2, the control unit 14 merely overrides the activation of the throttle lever 16. Therefore, it does not change the configuration of the thrust reverser control line to prevent improper deployment, including the logical and mechanical locks being located downstream of the FADEC or in a planar system that directly controls the third lock 24 (or TLS of the "third lock system"), independent of the rest of the system.

On board an aircraft equipped with a system according to the invention and/or capable of implementing a method according to the invention, the control of the thrust reversal system at the throttle lever 16 can be replaced or carried out by an emergency trigger button of the thrust reversal system.

In a system variant described in fig. 1, it may be provided that the control unit 14 is connected to the throttle lever 16 (connecting rod 16B) and receives information therefrom about the position of the throttle lever. This information may allow the control unit 14 to identify aborted takeoffs of the emergency landing box.

Fig. 2 shows a simplified logic diagram of the activation function of the thrust reverser system according to the invention. In fig. 2, the processing unit 13, the control unit 14, the FADEC 15 and the control system 20 of the thrust reverser 21 are schematically shown. In the example of fig. 3, the control unit 14 is connected to the processing unit 13 and the throttle lever 16. Thus, if the control unit 14 receives a corresponding signal (function "or", corresponding to the boolean operator "or") from the processing unit 13 or the throttle lever 16, the control unit 14 will issue an activation sequence of the thrust reverser system. This command is transmitted to the FADEC 15, and if other conditions are met, in particular the motor speed 22 is in idle condition, the wheels 23 are in contact with the ground and the tertiary lock 24 is deactivated, the FADEC 15 transmits it to the control system 20.

Fig. 2 further shows that the management system of thrust reversal (i.e., the members located in dashed box 25) need not be modified to integrate systems in accordance with the present disclosure. In fact, the members of the dashed box 25 in fig. 2 remain unchanged when implementing the invention, the system according to the invention only replacing the action of the pilot on the throttle stick. It should therefore be noted that the present invention does not alter the authentication process of the thrust reverser system.

Fig. 3 is a logic diagram of a landing procedure for an aircraft equipped with a system previously activated by the pilot in flight according to the present invention. In fact, it is recalled that the pilot may choose to deactivate the system according to the invention, which fig. 3 does not deal with.

The landing process shown in FIG. 3 begins with the approach phase (step 40). At this stage, the pilot is ready to land, including pre-selecting or not activating the automatic braking system or automatic braking (step 41).

If the pilot activates the automatic braking system (step 42), then the next step is landing (step 43). During landing, the pilot selects whether to activate or deactivate the thrust reverser (step 44). If the pilot chooses to activate the system, a thrust reverser is deployed (step 45). In this case, braking is provided by a combination of an automatic braking system and a thrust reverser system (step 46).

Of course, the pilot remains in motion possibility throughout the braking phase (step 47). If the pilot estimates that a braking-related action is required (step 48), the pilot may select between two different actions (step 49).

The first type of action (step 50) is a pilot action on the throttle lever that causes the automatic braking system to be deactivated (alternatively, the pilot action may be to directly deactivate the automatic braking system via a dedicated control button). In this case, the end of the braking phase is accomplished by manual actuation of the gas (management of the counterthrust system) and braking of the wheels (step 51). The following step is the end of the braking phase and thus the landing procedure (step 52).

The second type of action (step 53) includes a driver's action on a rudder pedal, which is a manual control of the wheel brakes. The two cases can then be distinguished according to the intensity of the pressure exerted on the rudder pedal by the driver (step 54). If the pressure is deemed high, that is, it is greater than a predetermined threshold (step 55), then the pilot's action may disable the automatic braking system 15 (step 56). The following step is the end of the braking phase and thus the landing procedure (step 52).

If the pressure applied by the pilot is deemed not to be strong, i.e., less than the predetermined threshold (step 57), then the action of the pilot will not cause the automatic braking system to be deactivated. The end of braking of the wheel brakes is then automatically managed, and the system according to the present disclosure may act on gas management when a slip is detected, i.e. when an alarm is issued by the anti-slip system (step 58). The following step is the end of the braking phase and thus the landing procedure (step 52).

If the pilot has not performed any action on the braking or thrust reversal control means (step 59) in step 47, braking is automatically performed. In particular, the motor speed is controlled by the automatic braking system and the anti-skid system (step 60). It is to be noted that within the scope of the invention, the system may act on the gas control to modify the intensity of the counterthrust, even if no slip is detected. The following step is the end of the braking phase and thus the landing procedure (step 52).

When in step 44 the pilot chooses not to activate the thrust reverser (step 61), then braking is provided by the automatic braking system alone, without the aid of the thrust reverser (step 62). Thus, at least at the beginning of the braking sequence (step 63), only wheel braking is applied. Indeed, according to the invention, the wheel braking system comprises an anti-slip system capable of detecting the slip of one or more wheels (between the braked wheels). If the anti-skid system sends a signal (step 64) representative of the occurrence of such a slip, this signal generates the activation of the thrust reverser (step 65) at the end of the process described above in relation to figure 1. Similar to step 46, the pilot retains the possibility of taking action on the control means, and therefore the following step is step 47 already described. If there is no slip (step 66), braking is performed by the automatic braking system, and only wheel braking is performed (step 67) until the braking phase is over. The following step is the end of the braking phase and thus the landing procedure (step 52).

If, in step 41, the pilot SI does not activate the automatic braking system (step 68), two cases are distinguished (step 69) according to whether the pilot has previously selected the activation of a "touch" thrust reverser system. If the pilot chooses to pre-select automatic deployment (step 70), the thrust reverser will automatically deploy to touch (step 71), i.e., when the aircraft lands. The braking phase is therefore performed by means of the activated counterthrust system (step 72).

However, the pilot may still control the intensity of the thrust reversals by manipulating or not manipulating the throttle lever (step 73).

If the pilot is acting on the throttle lever (step 74), braking is manually controlled by the pilot, including wheel braking and thrust reversal (step 75). The following step is the end of the braking phase and thus the landing procedure (step 52).

If the pilot is not acting on the throttle lever (step 76), the braking is manually controlled by the pilot and is limited to only wheel braking (step 77). However, if the anti-skid system detects one or more wheels slipping, the system according to the invention may act on gas monitoring to vary the intensity of the counter-thrust. The following step is the end of the braking phase and thus the landing procedure (step 52).

If in step 69 the pilot chooses not to pre-select automatic deployment of the thrust reverser (step 78), then the landing will proceed without automatic action (step 79), whether wheel braking or thrust reverser. However, the pilot remains on the possibility of activating or not activating the thrust reverser (step 80).

If the pilot has started the thrust reversal system (step 81), the following step is step 72, which has already been described.

If the pilot has not activated the thrust reverser system (step 82), braking is therefore only performed without thrust reverser assistance (step 83). Thus, at least at the beginning of the braking sequence (step 84), only the wheel brakes are applied (manually). If the anti-skid system sends a signal representing one or more wheels slipping (step 85), the signal will cause the thrust reverser system to activate (step 86) as described above. The next step is step 73, which has already been described. If the antiskid system (step 87) does not detect slip, braking is applied by wheel braking, only the wheel brakes are applied (step 88) until the end of the braking phase. The following step is the end of the braking phase and thus the landing procedure (step 52).

Claims (10)

1. A method of controlling the braking of an aircraft equipped with a landing gear having a braked wheel, the aircraft being driven by a turbojet engine and equipped with a thrust reverser system, the method comprising: estimating an adhesion of the brake wheel; and activating the thrust reverser system or modulating the thrust reverser generated by the thrust reverser system (if the thrust reverser system is already activated), depending on the estimated adhesion.

2. The method of claim 1, wherein if the estimated adhesion is less than a predetermined threshold, activating a thrust reversal system.

3. The method of claim 1, wherein estimating the tackiness is dependent on a slip rate of the braked wheel.

4. The method of claim 3, wherein a slip rate of the headblock is determined based on a rotational speed measurement of the headblock.

5. An aircraft equipped with a braked wheel and one or more turbojet engines equipped with a thrust reversal system, wherein the braking is controlled by the method of claim 1.

6. A brake control system for an aircraft equipped with a braked wheel and one or more turbojet engines equipped with a thrust reverser system, the brake control system comprising: a processing unit operable to determine a slip rate of a braked wheel and to generate a signal representative of an under-adhesion when the slip rate is greater than a predetermined threshold; a control unit can receive signals generated by a processing unit and control a reverse-thrust system according to the received signals.

7. The brake control system of claim 6, wherein the control unit activates the thrust reverser system when the determined slip rate is greater than the determined threshold.

8. The brake control system according to claim 6, wherein the control unit is connected to a regulation system of the turbojet or a FADEC (full authority digital engine control).

9. The brake control system according to claim 6, wherein the control unit is integrated into a turbojet regulation system or a FADEC (full authority digital engine control).

10. The brake control system of claim 6, wherein the slip rate of the braked wheel is determined based on information received by a speed sensor of the braked wheel.

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