Wheel braking device

Abstract

The present invention relates to a device (10) for braking a wheel (R), comprising: · - a brake which at least comprises a first actuator (11.1) and a second actuator (11.2), which are designed to apply a braking torque to the wheel (R); · - a control system (13), which is designed to control the first actuator and the second actuator respectively according to a required braking value; · - at least a first braking torque sensor (15.1), which is designed to provide a first measured value of the braking torque applied to the wheel by the brake to a control unit. According to the invention, the control system is designed to interrupt the control of the first actuator (11.1) or the control of the second actuator (11.2) when the braking torque measured by the first sensor (15.1) exceeds a pre-determined braking torque limit value.

Description

Technical Field

[0001] The present invention relates to the field of braking, and more particularly to a device for braking the wheels of a vehicle. The present invention is particularly applicable to the braking of the wheels of an aircraft landing gear. Background Art

[0002] To decelerate, stop or keep a vehicle stationary, pressure is usually applied to a brake pedal to cause the operation of a braking system. The braking system generally includes brakes that are mounted on the wheels of the vehicle and utilize the principle of friction between two surfaces that come into contact under pressure.

[0003] For a given depression or rotation of the pedal, the pressure is generally the same on each brake of the vehicle first, and then each brake is adjusted independently to generate an optimal braking torque on each wheel without locking them.

[0004] Such braking systems are reliable and effective, but they have the drawback of causing a large difference between the generated braking torque and the pressure applied to each wheel, especially between the start and the end of a braking operation, between a new brake and a worn brake, between one brake and another...

[0005] It is also recognized that this type of braking system is much more effective at low speeds than at high speeds, although braking performance is most critical at high speeds. Thus, the low-speed response of the braking system appears disproportionate and causes greater stress, which requires increasing the size of the structure supporting the brakes.

[0006] However, the lightweighting of aircraft has become an unavoidable goal for all aircraft manufacturers, especially in order to reduce the fuel consumption of aircraft. In particular, environmental standards require reducing pollutant emissions, especially reducing carbon dioxide (CO 2 ) emissions.

[0007] Very effective braking devices are disclosed in documents FR-A-3044432 and FR-A-3044296. Summary of the Invention

[0008] The object of the present invention is to propose a simple braking system that is at the same time robust and reliable and that can at least partially eliminate the above-mentioned drawbacks.

[0009] To this end, the present invention provides a braking device for braking a wheel, the device comprising:

[0010] - a brake that at least comprises a first actuator and a second actuator that are arranged to apply a braking torque to the wheel;

[0011] - A control system, which is arranged to control a first actuator and a second actuator respectively according to a required braking value; and

[0012] - At least a first braking torque sensor, which is arranged to provide a first measured value of the braking torque applied by the brake to the wheel to a control unit.

[0013] According to the present invention, the control system is arranged to interrupt the control of the first actuator or the control of the second actuator when the braking torque measured by the first sensor exceeds a predetermined braking torque limit.

[0014] Such a braking device enables protection to be provided in a simple manner against excessive braking torque, for example due to a failure of one of the actuators.

[0015] In a first embodiment, the control system includes an electronic control unit, which is arranged to deliver a first control signal to the first actuator and a second control signal to the second actuator. An electronic monitoring unit is arranged to prevent the delivery of the first control signal or the second control signal when the braking torque measured by the first sensor exceeds a predetermined braking torque limit value.

[0016] The monitoring unit can thus limit the braking torque actually applied to the wheel. This arrangement is particularly advantageous because it enables the impact of a control unit failure (for example due to an error in the computer program determining the control signal) to be limited.

[0017] In a second embodiment, the control system includes a first independent control unit arranged to deliver a first control signal to the first actuator and a second independent control unit arranged to deliver a second control signal to the second actuator.

[0018] This arrangement enables the control system to limit the braking torque applied by the brake to the wheel by interrupting the control of the first actuator or the second actuator according to whether the first control unit or the second control unit has failed. In the case of excessive torque, each individual electronic control unit can very quickly release the force generated by the actuator it controls, for example due to the failure of another control unit, thereby limiting the excessive torque applied by the braking device as a whole.

[0019] In particular, the control system includes a servo control loop for applying a control relationship based on both the required braking value and the braking torque measured by the first sensor to control the first actuator and the second actuator.

[0020] The servo control loop can thus finely control the braking torque applied by the brake to the wheel and thus, in particular, ensure a better distribution of the energy dissipated during braking among the various wheels of a vehicle provided with such a braking device.

[0021] In particular, the braking value represents the movement amplitude of the braking control instrument, such as the movement amplitude of the brake pedal.

[0022] In particular, the first actuator and the second actuator are electromechanical.

[0023] In a variant, the first actuator and the second actuator are hydraulic actuators.

[0024] In particular, the second torque sensor is arranged to provide a second measurement of the braking torque applied by the brake to the wheel to the control system.

[0025] Two braking torque sensors are used to make the device more reliable by doubling the measurement of the braking torque applied to the wheel.

[0026] Advantageously, in this case, the first braking torque sensor and the second braking torque sensor are of different technologies.

[0027] This limits the sensitivity of the two braking torque sensors to the same interference or the risk of suffering the same type of failure, such that the probability of the two braking torque sensors failing simultaneously is low. This improves the safety of the braking device of the present invention.

[0028] The present invention also relates to a landing gear comprising at least one wheel provided with such a braking device.

[0029] The present invention also relates to an aircraft comprising such a landing gear, and more particularly to a passenger aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be better understood in view of the following description, which is illustrative only and not restrictive, and must be read in conjunction with the accompanying drawings, in which:

[0031] Figure 1 Figure 1 is a simplified schematic view of an aircraft with a landing gear, the landing gear having wheels provided with the braking device of the present invention;

[0032] Figure 2 Figure 2 is a block diagram of the braking device in the first embodiment of the present invention; and

[0033] Figure 3 Figure 3 is a block diagram of the braking device in the second embodiment of the present invention. DETAILED DESCRIPTION

[0034] As Figure 1 ​​​​​​As shown, the aircraft A has two main landing gears L, each of which carries a so-called "braking" wheel R, i.e., equipped with a corresponding brake for braking the aircraft A when the aircraft A is on the ground. This specification relates to a single braking wheel R, but of course the invention applies in the same way to all or some of the braking wheels R of the aircraft A.

[0035] Referring Figure 2 And in a first embodiment of the invention, the braking device 10 for braking the wheel R includes a brake for braking the aircraft A. The brake includes, in a known manner, at least a first actuator 11.1 and a second actuator 11.2, which are arranged to press a stack of brake discs in order to apply a braking torque to the wheel R and thus slow down the rotation of the wheel. In this example, the first actuator 11.1 and the second actuator 11.2 are hydraulic actuators with the same capacity. The maximum braking torque is obtained when the first actuator 11.1 and the second actuator 11.2 simultaneously apply the maximum pressure they can generate on the brake discs.

[0036] The first actuator 11.1 is connected to the output of the first hydraulic servo valve 12.1 and the second actuator 11.2 is connected to the output of the second hydraulic servo valve 12.2. The first servo valve 12.1 and the second servo valve 12.2 respectively deliver pressurized fluid from the hydraulic unit to the first actuator 11.1 and the second actuator 11.2, so as to be able to control the respective positions of the first actuator 11.1 and the second actuator 11.2.

[0037] The first servo valve 12.1 and the second servo valve 12.2 are connected to the control system 13. Generally, the control system 13 includes an electronic control unit 13.1, which is arranged to deliver a first control signal S1 and a second control signal S2 to the first servo valve 12.1 and the second servo valve 12.2 respectively. The electronic control unit 13.1 is arranged to prepare the first signal S1 and the second signal S2 according to the pilot of the aircraft pressing the brake pedal 14, such that the first signal S1 and the second signal S2 represent the pressing of the brake pedal 14. To this end, the electronic control unit 13.1 includes in its memory one or more control relationships that relate the signals S1, S2 to the depression of the brake pedal.

[0038] The control system 13 is connected to a first brake torque sensor 15.1 and it includes an electronic monitoring unit 13.2 which is arranged to acquire a first measured value C1 provided by the first sensor 15.1 and continuously compare it with a pre - defined brake torque limit value. When the electronic monitoring unit 13.2 detects that the first measured value C1 provided by the first sensor 15.1 exceeds the pre - defined brake torque limit value, the electronic monitoring unit 13.2 is arranged to prevent the delivery of a first control signal S1 to a first servo - valve 12.1 or prevent the delivery of a second control signal S2 to a second servo - valve 12.2.

[0039] Thus, the electronic monitoring unit 13.2 is able to interrupt any untimely control of the first actuator 11.1 or the second actuator 11.2 and thus provides protection against any excessive torque, especially due to a failure of the electronic control unit 13.1.

[0040] Optionally, in a manner similar to the first sensor 15.1, the control system 13 may be connected to a second brake torque sensor 15.2 which is arranged on the brake to provide a second measured value C2 of the brake torque applied by the brake on the wheel R to the control system 13. The addition of the second sensor 15.2 serves to ensure better availability of the brake torque measurement by the electronic monitoring unit 13.2, especially in the case of a failure of the first sensor 15.1. The addition of the second sensor 15.2 also serves to ensure better reliability of the system by enabling it to detect drift in one of the sensors.

[0041] Advantageously, the first sensor 15.1 and the second sensor 15.2 are dissimilar, i.e., they are of different technologies so that they are not sensitive to the same interferences or do not undergo the same type of failures. Advantageously, the electronic monitoring unit 13.2 is arranged to monitor the sensors 15.1, 15.2 and optionally determine which of the first sensor 15.1 and the second sensor 15.2 provides an incorrect measurement of the brake torque. As an example, the method may include comparing the first measured value C1 provided by the first sensor 15.1 with the second measured value C2 provided by the second sensor 15.2 and analyzing the variations of the first measured value C1 and the second measured value C2 according to the depression of the brake pedal 14.

[0042] Furthermore, the electronic control unit 13.1 is advantageously arranged to execute a servo - control loop for delivering the first control signal S1 and the second control signal S2 in accordance with a control relationship based on the depression of the brake pedal 14 and the first brake torque measurement value C1 provided by the first sensor 15.1 and / or the second brake torque measurement value C2 provided by the second sensor 15.2.

[0043] Thus, the control system is arranged to convert the depression value of the brake pedal into a brake torque set value, and the electronic control unit 13.1 uses this set value to generate signal S1 and signal S2. The measurement of the brake torque is used both to modify the brake torque set value to deliver a brake torque corresponding to the depression value of the brake pedal and to apply a torque limit by stopping the fluid fed to one of the actuators if the measured brake torque value is greater than a predetermined threshold.

[0044] The servo control loop is used to control the brake torque applied by the brake to the wheel and, for example, ensures a better distribution of the energy dissipated during braking between the various wheels R of the brake provided with the braking device 10.

[0045] It should be noted that the control system 13 can be in the form of a computer processing unit, which generally includes at least one processor and a memory that contains a control program and a monitoring program executed by the processor to perform the above functions. Alternatively, the control system 13 can include two separate electronic circuits, each electronic circuit having its own computing and storage devices, namely one electronic circuit arranged to form a control unit and another electronic circuit arranged to form a monitoring unit.

[0046] Figure 3 The braking device 20 in the second embodiment of the present invention is shown.

[0047] As described above, the braking device 20 has a brake that has a first actuator 21.1 and a second actuator 21.2, and the first actuator 21.1 and the second actuator 21.2 are arranged to apply a brake torque to the wheel R. The first actuator 21.1 is connected to the output of the first hydraulic servo valve 22.1 and the second actuator 21.2 is connected to the output of the second hydraulic servo valve 22.2. The first servo valve 22.1 and the second servo valve 22.2 are connected to the control system 23, and the control system 23 is arranged to deliver a first control signal S11 to the first servo valve 22.1 and a second control signal S12 to the second servo valve 22.2. The signals S11, S12 represent the depression of the brake pedal 24. The control system 23 is also connected to a first brake torque sensor 25.1 arranged on the brake to provide a first measured value C11 of the brake torque applied by the brake to the wheel R to the control system 23.

[0048] The braking device 20 differs from the braking device 10 in that the control system 23 simultaneously includes a first electronic control unit 23.1 arranged to deliver the first control signal S11 and a second electronic control unit 23.2 arranged to deliver the second control signal S12.

[0049] In the case where a first measured value C11 of the braking torque provided by the first sensor 25.1 exceeds a predetermined braking torque limit value, the first electronic control unit 23.1 and the second electronic control unit 23.2 can each act to interrupt the delivery of the first control signal S11 and the second control signal S12.

[0050] Accordingly, the control system 23 serves to interrupt the control of the first actuator 11.1 or the second actuator 11.2 and thus provides protection against any excessive torque that may be caused by the failure of the first electronic control unit 23.1 or the second electronic control unit 23.2. In the case of excessive torque, each electronic control unit 23.1, 23.2 can very quickly release the force generated by the actuator 11.1, 11.2 it controls, e.g., due to the failure of the other control unit 23.2, 23.1, thereby limiting the excessive torque applied by the braking system as a whole.

[0051] In a manner similar to the braking device 10, the device 20 may optionally include a second braking torque sensor 25.2 arranged on the brake to provide a second measured value C12 of the braking torque applied by the brake to the wheel R to the control system 23.

[0052] Similarly, the first electronic control unit 23.1 and the second electronic control unit 23.2 may optionally include respective servo control loops for delivering the first control signal S11 and the second control signal S12 based on both the depression of the brake pedal 24 and the measured value of the braking torque. The implementation manner and advantages of the servo control of the two values are the same as those of the first embodiment.

[0053] Of course, the present invention is not limited to the described embodiments, but covers any variations that fall within the scope of the present invention defined by the claims.

[0054] Although in this example the first actuators 11.1, 21.1 and the second actuators 11.2, 21.2 are hydraulic, they may be electromechanical. Then preferably a control unit is provided that is connected to two power units, each power unit being connected to a respective one of the actuators.

[0055] The first actuators 11.1, 21.1 and the second actuators 11.2, 21.2 may be of different types.

[0056] The first actuators 11.1, 21.1 and the second actuators 11.2, 21.2 do not have to have the same capacity.

[0057] The number of actuators may be greater than two.

[0058] The number of braking torque sensors may be greater than two.

[0059] Although the two embodiments described above are described independently of each other, they can also be combined.

[0060] Although in this example the braking device is described with respect to an aircraft wheel, it can also be applied to the braking wheels of an automobile and, more generally, to the braking wheels of a means of transportation.

[0061] The braking setpoint can originate from depressing the brake pedal or even from activating any other control member, or even from a computer. Thus, the braking setpoint can be due to the pilot selecting the "autobrake" braking mode, which ensures a constant deceleration of the aircraft.

Claims

1. A braking device (10, 20) for braking a wheel (R), said braking device comprises: - a brake, said brake comprising at least a first actuator (11.1, 21.1) and a second actuator (11.2, 21.2), said first actuator and said second actuator being arranged to apply a braking torque to the wheel; - a control system (13, 23), said control system being arranged to control said first actuator and said second actuator respectively according to a required braking value; and - at least a first torque sensor (15.1), said first torque sensor being arranged to provide a first measured value (C1, C11) representative of the braking torque applied by said brake to said wheel to said control system; - said control system being arranged to interrupt the control of said first actuator or the control of said second actuator in the case where said first measured value (C1, C11) exceeds a predetermined braking torque limit.

2. The braking device (10) according to claim 1, characterized in that said control system (13) comprises: an electronic control unit (13.1), said electronic control unit (13.1) being arranged to deliver a first control signal (S1) to said first actuator (11.1) and a second control signal (S2) to said second actuator (11.2); and an electronic monitoring unit (13.2), said electronic monitoring unit (13.2) being arranged to prevent the delivery of said first control signal or said second control signal when said first measured value (C1, C11) exceeds said predetermined braking torque limit.

3. The braking device (10, 20) according to claim 1, characterized in that said control system (23) comprises a first independent electronic control unit (23.1) and a second independent electronic control unit (23.2), said first independent electronic control unit (23.1) being arranged to deliver a first control signal (S11) to said first actuator (21.1), said second independent electronic control unit (23.2) being arranged to deliver a second control signal (S12) to said second actuator (21.2).

4. The braking device (10, 20) according to claim 1, characterized in that said control system (13, 23) comprises a servo control loop for applying a control relationship according to both a required braking value and a first measured value (C1, C11) to control said first actuator (11.1, 21.1) and said second actuator (11.2, 21.2).

5. The braking device (10, 20) according to claim 1, characterized in that said braking value represents the movement amplitude of a braking control instrument (14, 24).

6. The braking device (10, 20) according to claim 1, characterized in that said first actuator (11.1, 21.1) and said second actuator (11.2, 21.2) are electromechanical.

7. The braking device (10, 20) according to any one of claims 1 to 5, characterized in that The first actuator (11.1, 21.1) and the second actuator (11.2, 21.2) are hydraulic actuators.

8. The braking device (10, 20) according to claim 1, characterized in that it includes a second torque sensor (15.2, 25.2), which is arranged to provide a second measurement value (C2, C12) of the braking torque applied by the brake to the wheel to the control system.

9. The braking device (10, 20) according to claim 8, characterized in that the first torque sensor (15.1, 25.1) and the second torque sensor (15.2, 25.2) have different technologies.

10. A landing gear (L) including at least one wheel (R), wherein the at least one wheel (R) is provided with the braking device (10, 20) according to any one of claims 1 to 9.

11. An aircraft (A) including the landing gear (L) according to claim 10.

Images