Eddy current magnetic brake device, vehicle brake wheel and aircraft landing gear, aircraft equipped with such wheel

Abstract

The invention relates to a magnetic braking device for a vehicle wheel, the device comprising: at least one stator element (2) arranged to be rotatably connected to a vehicle supporting a portion of the wheel; a rotor element (3) arranged to be rotatably connected to the wheel; a magnet for generating a magnetic flux between the elements, the magnetic flux being capable of generating an eddy current in one of the elements when the wheel rotates; and a brake control unit (11) that receives the brake command as an input to apply a braking force in accordance with the brake command. The magnet comprises at least one electromagnet (9), and the device comprises at least one anti-lock control unit (16) which receives as input a vehicle speed signal and a wheel rotation speed signal and provides as output a signal controlling the electromagnet as a function of a comparison of the speeds from the signals received as input. The invention also relates to an aircraft wheel and a landing gear comprising such a device.

Description

Technical Field

[0001] This invention relates to the field of braking for vehicle wheels, such as aircraft wheels. Background Technology

[0002] Aircraft wheels typically consist of a rim surrounded by a tire and connected by a web to a hub mounted to rotate on a wheel support axle (wheel axle or spindle).

[0003] Known friction braking devices include a stack of brake discs housed in an annular space extending between a rim and a hub. This stack comprises alternating rotor discs rotatably connected to the wheel and stator discs fixed relative to a wheel support shaft. The braking device also includes a hydraulic or electromechanical actuator mounted on an actuator carrier and arranged to apply a clamping force to the stack of discs, thereby generating a braking torque to brake the rotation of the wheel.

[0004] Many vehicles equipped with friction brakes have an anti-lock braking (or anti-skid) wheel system associated with the friction brakes. In practice, if the braking torque is too high relative to the vehicle's speed and the coefficient of friction between the wheel / tire and the ground, the brakes lock the wheels, causing them to slip on the ground. This slippage reduces the vehicle's maneuverability and leads to tire wear and rapid heating, which can cause a tire blowout. To prevent wheel lock-up, the anti-lock braking system compares the wheel's rotational speed with the vehicle's speed and controls the actuators to release the clamping force when the speed ratio exceeds a threshold (roughly corresponding to the wheel's circumference). For effective anti-lock braking, the clamping force must be released within a response time of 50 to 100 milliseconds, a response time compatible with most friction brakes.

[0005] Eddy current magnetic braking devices are further known for braking vehicle wheels, and more specifically, for braking aircraft wheels. Document FR-A-3122405 describes such a device comprising: a rotor rotatably connected to the wheel; two stators surrounding the rotor, the stators being rotatably connected to a wheel support shaft and freely translatable relative to said shaft; a magnet for generating axial magnetic flux between the stators and the rotor; and a linear actuator for axially moving the stator between a maximum braking position near the rotor and a free rotation position away from the rotor.

[0006] In eddy current magnetic braking devices, the generated braking torque increases with the relative rotational speed of the rotor relative to the stator, and decreases along with the relative rotational speed. Therefore, no anti-lock braking system is designed for the wheels. However, using eddy current braking devices also appears to carry the risk of wheel lock-up.

[0007] Therefore, it was envisioned that the actuator be driven to move the rotor and stator apart, as in the anti-lock braking system of a friction brake. However, it has been determined that the actuator stroke required to sufficiently reduce the braking torque to avoid wheel lock-up is five times greater in a magnetic brake than in a friction brake. Consequently, the response time of a conventional magnetic brake is too high, rendering it ineffective for anti-lock braking. Summary of the Invention

[0008] The present invention is particularly intended to provide a braking device that at least partially overcomes the above-mentioned disadvantages.

[0009] Therefore, according to the present invention, an eddy current magnetic braking device for a vehicle wheel is provided, comprising: at least one stator element arranged rotatably connected to a portion of the vehicle supporting the wheel; a rotor element arranged rotatably connected to the wheel; a magnet for generating magnetic flux between the elements, the magnetic flux generating eddy currents in one of the elements when the wheel rotates; and a brake control unit for receiving a braking command or brake control as input, and for applying a braking force according to the brake control. The magnet includes at least one electromagnet, and the device includes at least one anti-lock braking control unit that receives a vehicle speed signal and a wheel rotation speed signal as input, and provides a signal for controlling the electromagnet as output based on a comparison of the speeds derived from the received input signals.

[0010] The comparison of speeds derived from the received input signal allows the anti-lock braking control unit to detect wheel lock-up and provide a control signal to the electromagnet at the output to correct it. By driving the electromagnet, the generated magnetic flux can be canceled very quickly, thereby canceling the braking torque. Therefore, it has been found that anti-lock braking using an electromagnet is several times faster than anti-lock braking using modified stator / rotor air gaps to increase or decrease braking torque in eddy current braking devices. Specifically, when the air gap increases, the time required to decrease braking torque is longer than when the electromagnet current decreases. The same phenomenon is observed when the air gap decreases: the time required to increase braking torque is longer than when the electromagnet current increases. Therefore, the anti-lock response time by modifying the electromagnet current is relatively short: modifying the electromagnet's supply current allows the change in braking torque to be equivalent to the rapid release of clamping force in a friction brake. Furthermore, the anti-lock control circuit can have a fast dynamic response.

[0011] Preferably, the anti-lock braking control unit is arranged to control the electromagnet to generate a decrease in braking torque when wheel lock-up is detected, and then to generate an increase in braking torque when wheel lock-up is eliminated, wherein the anti-lock braking control unit controls the electromagnet so that the increase in braking torque is slower than the decrease in braking torque.

[0012] This allows for limiting the risk of rapid wheel jamming when braking force is applied.

[0013] The present invention also relates to a brake wheel equipped with such a device; a landing gear including a strut, one end of which carries a shaft, the hub of such a wheel being mounted on the shaft, the stator element of the braking device being rotatably connected to the strut via the shaft; and an aircraft equipped with such a landing gear.

[0014] Other features and advantages of the invention will become apparent when reading the following description of specific and non-limiting embodiments. Attached Figure Description

[0015] Please refer to the attached diagram, in which:

[0016] [ Figure 1 ] Figure 1 This is a partial schematic front view of an aircraft equipped with landing gear according to the present invention;

[0017] [ Figure 2 ] Figure 2 This is a partial schematic view of the wheel according to the present invention in an axial half-section;

[0018] [ Figure 3 ] Figure 3 This is a partial schematic perspective view of the stator and rotor of the braking device used for this wheel;

[0019] [ Figure 4 ] Figure 4 It is a curve that correlates the slip ratio (equal to 1 minus the ratio of the product of the wheel's angular velocity and the wheel's radius to the vehicle's speed) and the coefficient of friction (Mu) for a given state of the runway used by the aircraft (in this case, a dry runway);

[0020] [ Figure 5 ] Figure 5 The modification of the electromagnet supply current is shown, along with the superposition of the target current and the electromagnet supply current.

[0021] [ Figure 6 ] Figure 6 The curves representing the braking torque response time after air gap correction and the curve representing the braking torque response time after electromagnet power supply current correction are superimposed.

[0022] [ Figure 7 ] Figure 7 The diagram shows the change in braking torque over time obtained by modifying the electromagnet power supply current.

[0023] [ Figure 8 ] Figure 8 This is a schematic diagram of the logic circuit for controlling braking according to the present invention. Detailed Implementation

[0024] refer to Figures 1 to 3The braking system according to the invention is carried by an aircraft 100 including landing gear 101. Each landing gear 101 includes a strut with two coaxial shafts 102 at one end, each shaft having a wheel 103 mounted for pivoting. Each wheel 103 includes, in a manner known per se, a hub 104 mounted on the shaft 102 for pivoting and a rim 105 connected to the hub 104 via a web 106. The rim 105 and the hub 104 define an annular space between them, one end of which is closed by the web 106 and the other end open toward the outside of the wheel 103. The rim 105 is surrounded by a tire (not shown).

[0025] According to the invention, wheel 103 is equipped with a magnetic braking device (generally marked as 1), which extends into the annular space defined by rim 105 and hub 104.

[0026] The magnetic braking device 1 includes a fixed element or stator 2 and a movable element or rotor 3.

[0027] More specifically, in this case, the stator 2 and rotor 3 are disc-shaped and coaxial with the wheel 103, thus having collinear central axes. The rotor 3 is arranged between the two stators 2 and has two opposing principal surfaces 3.1, each facing one of the principal surfaces 2.1 of the stator 2. Principal surfaces 2.1 and 3.1 are parallel to each other.

[0028] The stator 2 is rotatably connected to the strut of the shaft 102 or the landing gear 101, hereby by means of a ribbed torsion tube 4 fixed to the outer flange of the shaft 102: the stator 2 is engaged with the torsion tube 4. The rotor 3 is rotatably connected to the wheel 103, in this case by means of a rod protruding toward the inside of the wheel rim 105. Thus, the rotor 3 rotates about its central axis relative to the stator 2 surrounding it: during the circumferential movement of the rotor 3, the main surface 3.1 remains opposite to and parallel to the main surface 2.1.

[0029] Each stator 2 is mounted to slide (without rotation) above the torsion tube 4, and is movable in the axial direction of the torsion tube 4 between a first position or maximum braking position and a second position or free rotation position. In the first position or maximum braking position, the rotor 3 and stator 2 are close to each other, their main surfaces 3.1, 2.1 separated by a predetermined first air gap. In the second position or free rotation position, the rotor 3 and stator 2 are spaced apart from each other, their main surfaces 3.1, 2.1 separated by a predetermined second air gap larger than the predetermined first air gap. Each stator 2 is connected to at least one electromechanical actuator, designated 6, via a mechanism designated 5, which can be controlled by the aircraft pilot in a manner known per se to actuate the mechanism 5 to move the stator 2 between the two positions. For example, the actuator may be a linear actuator, and the mechanism may be a direct connection between the movable element of the actuator and the stator or include one or more intermediate levers; the actuator may be rotatable, and the mechanism may be a screw / nut system. An axial abutment, of the type of bearing abutment or needle roller abutment, is provided and inserted between the rotor 3 and the stator 2 (or between the components connected to them) to ensure that the stator 2 cannot move close to the rotor 3 beyond the first air gap.

[0030] Each stator 2 includes a plurality of permanent magnets 7, the magnetic field of which can generate eddy currents in the rotor 3 when the stator 2 is in a first position and the rotor 3 pivots in front of the stator 2. The permanent magnets 7 in this case are rare earth based and are preferably fixed to a support member 8, for example, made of magnetic steel.

[0031] Each stator 2 also includes a plurality of electromagnets 9, which are alternately fixed to the support 8 along with permanent magnets 7. The electromagnets 9 include coils connected to a current source and are sized to generate a magnetic field that cancels out the magnetic field generated by the permanent magnets 7 or even reverses the magnetic field emitted by the stator 2.

[0032] Rotor 3 is made of copper or any other conductive material. Each rotor 3 has a thickness such that a skin effect (otherwise called the epidermal effect or Kelvin effect) is generated from each face 3.1 of rotor 3, covering more than half of the thickness of rotor 3, and at least covering the possible range of relative speeds of rotor 1 relative to stator 2. Therefore, eddies generated from both faces 3.1 will circulate in the central portion of each rotor 3, which will increase braking torque. Thus, a “superposition of skin effects” is achieved, with the thickness of rotor 3 being low enough to achieve this effect while satisfying both thermal and mechanical stresses. In one example, this effect improves performance by approximately 60%.

[0033] Now we will examine braking control in more detail.

[0034] It should be understood that, in order to induce braking, the control electromechanical actuator 6 brings the stator 2 to the first position, and in order to interrupt braking, the control electromechanical actuator 6 brings the stator 2 to the second position, in which the permanent magnet 7 is not allowed to generate sufficient eddy currents in the rotor 3 to induce braking of the rotor 3.

[0035] It should be noted that below a certain rotational speed of rotor 3, the braking torque is negligible regardless of the stator position. Therefore, additional braking may be necessary.

[0036] It should also be understood that braking can be interrupted by supplying power to the electromagnet 9 to counteract the magnetic field generated by the permanent magnet 7.

[0037] Now refer to Figure 8 The control circuit 10 describes the electromechanical actuator 6 and the electromagnet 9.

[0038] The brake control circuit 10 defines a brake servo loop and includes a brake control unit 11 (or BCU), which has:

[0039] - A first input, which is connected to a braking control instrument actuated by the pilot of the aircraft 100.

[0040] - A second input, which is connected to the return path of the braking circuit.

[0041] - First output, which is connected to the first input of the first adder 12.

[0042] - Second output, which is connected to the first input of the second adder 13.

[0043] The first adder 12 has an output that is connected to the input of an actuator control unit 14 (or ACU) that has an output connected to the actuator 6.

[0044] The second adder 13 has an output that is connected to the input of an electromagnet control unit 15 (or CCU) that has an output connected to an electromagnet 9.

[0045] The braking control circuit 10 also includes an anti-lock braking control unit 16, which has:

[0046] - A first input, which is connected to the communication bus of the aircraft 100, to receive the speed of the aircraft 100, in particular, provided by the sensors of the aircraft 100, such as the speed relative to the ground (inertial, GNSS or hybrid) provided by the navigation unit of the aircraft 100.

[0047] - A second input, which is connected to an angular velocity sensor 17 arranged to determine the rotational speed of wheel 103;

[0048] - First output, which is connected to the second input of the first adder 12;

[0049] - Second output, which is connected to the second input of the second adder 13.

[0050] Units 11, 14, 15, and 16 are electronic units whose structure is known in itself. They may include one or more integrated circuits, microcontrollers, FPGAs, or other components.

[0051] The brake control unit 11 includes, for example, a computer in the form of an integrated circuit, which is programmed to process signals from its inputs to generate:

[0052] - Brake actuator control signal sent to the first output;

[0053] - Electromagnetic braking control signal sent to the second output.

[0054] The anti-lock braking control unit 16 includes, for example, a computer in the form of an integrated circuit, which is programmed to process signals from its inputs to generate:

[0055] - Actuator anti-lock control signal sent to the first output;

[0056] - Electromagnetic anti-lock control signal sent to the second output.

[0057] The first adder 12 outputs an actuator control signal (corresponding to an actuator braking control signal or an actuator anti-lock control signal, as will be seen below).

[0058] The second adder 13 outputs an electromagnet control signal (corresponding to an electromagnet braking control signal or an electromagnet anti-lock control signal, as will be seen below).

[0059] The actuator control unit 14 includes, for example, a computer in the form of an integrated circuit, which is programmed to process actuator control signals arriving at its input to generate actuator power signals for powering the actuator 6 via power circuitry associated with the control circuitry.

[0060] The electromagnet control unit 15 includes, for example, a control circuit in the form of an integrated circuit, programmed to process electromagnet control signals arriving at its input to generate an electromagnet power signal for powering the electromagnet 9 via a power circuit associated with the control circuit. Figure 5 As shown, the electromagnet power signal supplying electromagnet 9 can vary between positive and negative values ​​as needed.

[0061] During operation, the anti-lock braking control unit 16 stores the radius of the tires used by the aircraft 100 in its memory, and can calculate the slip ratio based on this radius, the rotational angular velocity provided by the tachometer 17, and the speed of the aircraft 100 provided by the communication bus, and compare it with a threshold, which is set to 0.12 in the case of a dry runway (see [link to relevant documentation]). Figure 4 The threshold here corresponds to the optimal slip ratio: as long as the slip ratio is less than or equal to this threshold, the tire is in a stable region, and braking is considered to be performed without wheel lock-up. If the slip ratio exceeds the threshold, slippage is detected.

[0062] Provided no slippage is detected, electromagnet 9 and actuator 6 are controlled solely by brake control unit 11, without intervention from anti-lock braking unit 16, to transmit braking torque proportional to the pilot's braking control. Brake control unit 11 sends control signals to actuator control unit 14 to correct the air gap value between stator 2 and rotor 3, and / or to electromagnet control unit 15 to modify the magnetic field generated by electromagnet 9 according to the pilot's required braking force. Correcting the air gap via actuator 6 and modifying the magnetic field via electromagnet 9 will increase or decrease the braking torque, thereby changing the speed of aircraft 100. Correcting the air gap via actuator 6 affects the magnetic flux transmitted to rotor 3 by permanent magnet 7 and electromagnet 9 (under constant supply current). Modifying the supply current of electromagnet 9 affects the magnetic flux transmitted to rotor 3 by electromagnet 9, and also affects the magnetic flux transmitted by permanent magnet 7, because electromagnet 9 can cancel the magnetic field transmitted by permanent magnet 7.

[0063] Using this example, the brake control unit 11 can be configured as follows:

[0064] - Only applies to actuator 6, provided that the rate of change of braking force requested by the pilot (e.g., determined based on the amplitude of movement of the control instruments he manipulates) is less than a threshold; and

[0065] - When the rate of change of braking force required by the pilot (e.g., determined based on the amplitude of movement of the control instruments he manipulates) exceeds a threshold, it works in conjunction with actuator 6 and electromagnet 9.

[0066] In the second case, it should be understood that the braking torque is distributed between the permanent magnet 7 and the electromagnet 9. This distribution can vary over time during braking:

[0067] - At the start of braking, by modifying the forces acting on actuator 6 and electromagnet 9, for example, by the same magnitude, but with the increase in magnetic flux of electromagnet 9 being much faster than that of permanent magnet 7, electromagnet 9 contributes a larger share to the increase in braking torque.

[0068] As braking continues and the air gap between rotor 3 and stator 2 decreases, the braking control unit 11 can reduce the power supply current to electromagnet 9 to balance the contributions of permanent magnet 7 and electromagnet 9 to braking torque, and even ensure that the contribution of permanent magnet 7 gradually replaces the contribution of electromagnet 9.

[0069] The brake control unit 11 can be configured in the same manner to release the braking force. Of course, other strategies for controlling the actuator 6 and the electromagnet 9 are also possible for applying or releasing the braking force.

[0070] Once slippage is detected, the anti-lock braking control unit 16 sends an interruption signal to the brake control unit 11. The output of the brake control unit 11 is blocked, and the anti-lock braking control unit 16 takes over control of the braking circuit. Based on the difference between the aircraft speed calculated from the wheel's rotational speed and the aircraft speed from the communication bus, the anti-lock braking control unit 16 then sends a control signal to the electromagnet control unit 15 to modify the magnetic field generated by the electromagnet 9, and possibly to the actuator control unit 14 to correct the air gap value between the stator 2 and the rotor 3. The actuator control unit 14 sends voltage to the actuator 6 to correct the air gap value. The electromagnet control unit 15 sends voltage to the electromagnet 9 to modify the current in the electromagnet 9. These actions are designed to reduce braking torque and release / unlock wheel 103 to stop slippage.

[0071] Once the anti-lock braking control unit 16 detects a stop in slippage, the torque is gradually increased (adjusted by means of an electromagnet and / or air gap) according to the actual conditions (dry, wet, or icy track) to a value that roughly corresponds to the theoretically optimal slip ratio between the tire and the ground (the anti-lock braking control unit 16 stores such values ​​in its memory). Figure 4 (The curves or tables corresponding to different runway conditions). Information on actual conditions is provided to the aircraft, for example, by the airport control tower and transmitted to the anti-lock control unit 16 via a communication bus.

[0072] Since anti-lock braking using electromagnet 9 is several times faster than anti-lock braking using actuator 6 to adjust the air gap to increase or decrease torque, it is preferable to modify the supply current of electromagnet 9 to perform the anti-lock function and reduce the braking torque. Specifically, the braking torque must be reduced abruptly to minimize the duration of wheel lock-up. Figure 6 The diagram illustrates the difference in response time between anti-lock braking by modifying the air gap and anti-lock braking by modifying the current of electromagnet 9 (it is illustrative because it does not represent the actual behavior of the brakes, and the actual variation in the amplitude of the electromagnet torque depends on the arrangement of magnets 7 and 9).

[0073] If necessary, and if a greater torque variation is required, the air gap can be corrected (via actuator 6) while modulating the current of electromagnet 9. This combination improves the anti-lock braking efficiency of the eddy current brake.

[0074] Although the braking torque must decrease as quickly as possible, it is necessary to ensure that the braking torque gradually increases after a rapid decrease, the opposite of a sudden decrease in braking torque. Figure 7 As shown. Therefore, the anti-lock braking control unit 16 is arranged to control the electromagnet 9 to reduce the braking torque when wheel lock-up is detected, and then to increase the braking torque when wheel lock-up disappears. The anti-lock braking control unit 16 controls the electromagnet 9 so that the increase in braking torque is slower than the decrease in braking torque. From Figure 7 As can be seen, the increase in braking torque follows a curve that varies with time, with an initial straight line segment that is approximately vertical (about 80°) and a final segment where the slope gradually decreases to zero when the maximum braking force is applied. Figure 7 The curves show that the anti-lock braking system responds very quickly when applied to the electromagnet 9, and is faster in any case than when applied only to the air gap.

[0075] The electromagnet allows the braking torque to increase gradually while avoiding instability in the anti-lock braking circuit.

[0076] Therefore, according to the first control mode, the electromagnet is controlled between three states: a first positive intensity value, a second zero intensity value, and a third intensity value that is the opposite of the first value.

[0077] The second control mode involves directly modifying the time constant of the control electromagnet 9 in the anti-lock braking control unit 16 according to the required braking torque. Thus, by way of example, the supply current of the electromagnet is controlled in 1% steps between two extreme values ​​corresponding to +100% and -100% of the maximum current value. Therefore, the braking torque is actively modulated.

[0078] The third control mode includes a combination of air gap control and electromagnet 9 current control, for example, according to one of the first two control modes.

[0079] Naturally, the present invention is not limited to the embodiments described, but includes any variations that fall within the scope of the invention as defined in the claims.

[0080] In particular, the structure of the device may differ from the structure described above.

[0081] The magnet can be supported by the rotor instead of the stator, with two rotors connected to one stator on the side.

[0082] The shape, arrangement, and size of the magnets may differ from those described. For example, the magnets may have different sizes and / or be arranged according to a Halbach pattern.

[0083] The number of rotors and / or stators may differ from the stated number.

[0084] Although the rotor and stator are described as parallel discs facing each other, the stator and rotor can have other forms. The device is axial flow, but the invention is applicable to radial flow operation or a hybrid operation combining axial and radial flow. Therefore, the stator can, for example, be arranged as an outer drum and an inner drum, with a central drum forming the rotor extending between the outer and inner drums, such that the central drum has an outer surface opposite the inner surface of the outer drum and an inner surface opposite the outer surface of the inner drum. Magnets are carried by the outer surface of the inner drum and the inner surface of the outer drum.

[0085] The magnetic braking device according to the invention can be associated with a conventional friction braking device, which includes a friction element, such as a carbon disc stack, and a plurality of electromechanical actuators carried by an actuator carrier. Each electromechanical actuator includes an electric motor and a push rod movable by the electric motor to press the disc stack. Thus, the electromechanical actuators are intended to generate a controlled braking force on the disc stack. A method for controlling a braking device is known, for example, from document FR-A-2953196.

[0086] Alternatively, the magnets can be directly fixed to the rotor or stator discs of the friction brake, or the magnets can be covered by friction linings, such that the braking device ensures magnetic braking to slow the wheel speed when the discs are separated from each other by a suitable air gap, and friction braking when the discs abut against each other. Therefore, in this embodiment, there are no longer axial abutments between the discs.

[0087] For the mechanical actuation of magnetic braking devices, actuators can be used that act on several stators, which slide in the same direction to approach adjacent rotors, rather than one actuator per stator. A single actuator can also act on two stators to make them move in opposite directions.

[0088] Electromagnets 9 are controlled here to generate braking torque together with the permanent magnets. They may only be used to counteract the magnetic field of the permanent magnets in the event of lockup. However, preferably, the electromagnets are driven to operate together with the permanent magnets, thereby supplementing the magnet array and, consequently, the magnetic field, allowing it to operate in an optimal manner. This is especially true in Halbach arrays, where the interaction between adjacent magnets in the magnet array is significant.

[0089] The device may consist of only an electromagnet.

[0090] Figure 8 The logic example shown is only one possible solution, and other logic arrangements can be envisioned to incorporate one or both of the anti-slip control means of eddy current braking: for example, by using both air gap control and electromagnet control, or by using only electromagnet control.

[0091] The control mode can be determined, for example, based on a combination of external information, such as runway conditions or atmospheric conditions, to establish a first, second, and third external condition. In the first external condition, coarse control of the electromagnet is sufficient (first control mode); in the second condition, fine control is required (second control mode); and in the third condition, even finer control is needed (third control mode). Any useful parameters (aircraft speed, wheel speed, torque, etc.) can be used to create servo or feedback loops in the control of the braking system.

[0092] Other actuation modes of the magnetic brake can be envisioned: for example, using only coils that generate a magnetic field to counteract the magnetic field of the permanent magnet, with the rotor and stator axially fixed.

[0093] Alternatively, the first adder 12 can output the actuator control current obtained by subtracting the actuator anti-lock control signal from the actuator braking control signal. In the same manner, the second adder 13 can output the electromagnet control current obtained by subtracting the electromagnet anti-lock control signal from the electromagnet braking control signal.

[0094] Support 8 may be made of non-magnetic material.

[0095] This invention can be used in any type of vehicle, such as air, land or amphibious vehicles, or for applications other than vehicles, such as for any industrial or transport mobile equipment that requires braking.

Claims

1. An eddy current magnetic braking device for vehicle wheels, comprising: At least one stator element (2) is arranged to be rotatably connected to a portion of the vehicle that supports the wheel; Rotor element (3) arranged to be rotatably connected to the wheel; A magnet for generating magnetic flux between the elements, the magnetic flux generating eddy currents in one of the elements when the wheel rotates; and a brake control unit (11) for receiving brake control as input to apply braking force according to the brake control, characterized in that the magnet includes at least one electromagnet (9), and the device includes at least one anti-lock braking control unit (16) that receives a vehicle speed signal and a wheel rotation speed signal as input, and provides a control signal for the electromagnet as output based on a comparison of the speeds derived from the received input signals.

2. The apparatus according to claim 1, characterized in that, The anti-lock braking control unit (16) is arranged to control the electromagnet (9) to cause a decrease in braking torque when wheel lock-up is detected, and then to cause an increase in braking torque when the lock-up is removed. The anti-lock braking control unit (16) controls the electromagnet (9) so that the increase in braking torque is slower than the decrease in braking torque.

3. The apparatus according to claim 2, characterized in that, The increase in braking torque follows a curve that changes over time, with a straight initial segment having a substantially vertical slope and a final segment where the slope gradually decreases to zero.

4. The apparatus according to any one of the preceding claims, characterized in that, The comparison is based on calculating the slip ratio of the wheel relative to the ground, and the anti-lock braking control unit (16) operates when the calculated slip ratio is greater than the optimal slip ratio.

5. The apparatus according to any one of the preceding claims, characterized in that, The magnet includes a permanent magnet (7) carried by one of the elements, and the device includes at least one actuator (6) for correcting the air gap between the elements, the anti-lock control unit (16) being connected to the actuator to correct the air gap based on a comparison of the speed derived from the received signal as input.

6. The device according to claim 5, comprising a plurality of electromagnets (9), each of the electromagnets being inserted between two of the permanent magnets (7).

7. The apparatus according to claim 5 or 6, characterized in that, The brake control unit (11) and the anti-lock braking control unit (16) each have a first output and a second output. The first output is connected to a first adder (12), which is connected to the control unit (14) of the actuator (6). The second output is connected to a second adder (13), which is connected to the control unit (15) of the electromagnet (9).

8. A braked vehicle wheel (103) comprising a rim (105) and a hub (104) connected by a web (106), the web defining an annular space for receiving a braking device according to any one of the preceding claims.

9. A landing gear (101) comprising a strut (102) at one end of the strut carrying a shaft (102), wherein the hub of a wheel (103) according to claim 8 is mounted on the shaft (102), and the stator element (2) of the braking device is rotatably connected to the strut (102).

10. An aircraft comprising at least one landing gear as claimed in claim 9.

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