Aircraft braking system

Abstract

A routine maintenance procedure performed on a wheel 116 of an aircraft landing gear. The wheel is integrated with a consumable brake lining material. As part of the routine maintenance procedure, the retreading or replacement of the tire (1014 in FIG. 4) and the inspection or replacement of the consumable brake lining material of the tire (1016 in FIG. 4) are performed at the same continuous intervals (1012, 1018, 1020, etc. in FIG. 4). This can reduce the overall volume and total mass of the brake material present on the aircraft. The brake material provided to meet the requirements of a maximum energy rejected takeoff (e.g., the brake material located on the stator 150 and / or rotor 152 of the outboard brake kit) can be provided separately (e.g., separately from the brake material on the stator 120 and / or rotor 122 integrated with the wheel). The wheel can be made of a carbon fiber composite material as one or two components. At least some of the brake material can be disposed on the outward-facing flat surface of the wheel.

Description

Technical Field

[0001] The present invention relates to an aircraft braking system and an aircraft wheel having an integrated braking assembly. More specifically but not exclusively, the present invention relates to a particular arrangement of an aircraft wheel and an associated braking assembly and a method of maintaining the same. The present invention also relates to a braking method and other subjects described and claimed herein. Background Art

[0002] It is known in the prior art to provide a braking assembly as part of an aircraft wheel. Many such proposals have been made, including for example those disclosed in US2,854,098 and US2,672,220. Wheels of such systems tend to be heavy. There is a general desire to reduce unnecessary mass on an aircraft in order to, for example, increase fuel efficiency. In many prior art solutions, the braking assembly integrated with the wheel is complex. There is also a general desire to be able to perform efficient maintenance on an aircraft during its service life.

[0003] The present invention is intended to solve one or more of the above problems. Alternatively or additionally, the present invention is intended to provide, for example, an improved aircraft wheel and / or a braking system associated with such a wheel that allows for a reduction in mass. Alternatively or additionally, the present invention is intended to provide, for example, an improved aircraft wheel and / or a braking system associated with such a wheel that allows for more efficient maintenance. Alternatively or additionally, the present invention is intended to provide an improved method for performing maintenance on an aircraft wheel and / or a braking system associated with such a wheel. Summary of the Invention

[0004] According to a first aspect, the present invention provides a method of performing a routine maintenance procedure on a wheel of an aircraft landing gear. The wheel includes a tire and a consumable brake lining material (i.e., as part of the wheel). The method includes resurfacing or replacing the tire at successive intervals as part of the routine maintenance procedure. The method also includes inspecting or replacing the consumable brake lining material of the tire at the same successive intervals. Thus, in certain embodiments of the present invention, the routine maintenance of the tire is synchronized with the routine maintenance of the brake lining material on the wheel. In embodiments of the present invention, this eliminates the need for a separate, potentially independent and asynchronous maintenance schedule for the brake material. In embodiments of the present invention, the required routine maintenance of the aircraft can be reduced and / or at least partially replaced by performing maintenance on the wheel when the wheel is removed from the aircraft, thereby improving operational efficiency. In addition to the need to replace or replenish the brake material, the frequency of brake inspections can be increased, enabling early detection of maintenance problems.

[0005] It will be understood that the following is within the scope of the present invention: At the end of a single maintenance interval, only one retread or replacement of the tire is performed while inspecting and subsequently replacing at least some of the consumable brake lining material tires.

[0006] It will be understood that the routine maintenance of the wheels and / or brake linings, brake assemblies, etc. is maintenance performed at a set minimum period or operating cycle, etc. Other non-routine maintenance can be performed when needed in response to special circumstances or as required, for example, after a certain emergency. The consecutive intervals can be determined by the maximum number of periods allowed between consecutive maintenance procedures. The consecutive intervals can be set by requiring actual maintenance as soon as possible after a certain number of periods. The number of periods can be set to achieve uninterrupted operation between predetermined maintenance cycles. In an embodiment of the present invention, the number of aircraft operating cycles between one routine maintenance and the next can be at least 100. The number of aircraft operating cycles between one routine maintenance and the next can be greater than 200 and can optionally be less than 500.

[0007] The mass of the consumable brake lining material carried by each landing gear can be reduced. The mass of the consumable brake lining material used between successive inspections of the consumable brake lining material can be reduced. The mass of the consumable brake lining material carried by each wheel can correspond to the amount set by a shorter interval between successive maintenance procedures. At least a quarter, preferably at least a third, and possibly a majority of the consumable brake lining material can be used within five successive intervals (the used consumable brake lining material can be considered, for example, as the difference in mass between the consumable brake lining material forming part of the wheel at the initial, peak level and the mass just prior to the fifth retread / replacement of the tyre on the wheel as part of a routine maintenance procedure). The routine maintenance procedure can be carried out for a plurality of wheels, each wheel including a tyre and the consumable brake lining material forming part of the wheel. The method can be carried out such that for a sample of fifty steps of replacing the consumable brake lining material (the fifty steps being optionally a series of steps carried out successively at the same location and / or for the same fleet of aircraft, but optionally a random sample), at least five of these steps correspond to a situation where a majority of the consumable brake lining material has been used within the aforementioned five successive intervals (or optionally, if the brake lining material is replaced earlier than within five successive intervals, at least five of these steps correspond to the situation where a majority of the consumable brake lining material has been used since the previous replacement of the brake material). A majority of the consumable brake lining material can be used for approximately 10% of the time (within five successive maintenance intervals). The replacement frequency of the consumable brake lining material can be lower than each routine maintenance procedure and optionally lower than each other routine maintenance procedure. On average, the replacement frequency of the consumable brake lining material can be higher than once every twenty routine maintenance procedures and optionally higher than once every ten routine maintenance procedures. The mass of the consumable brake lining material used during five successive intervals (i.e. five tyre retreads / replacements) can be in the range of 3 kg to 20 kg (optionally 4 kg to 15 kg) per wheel and may be greater than 5 kg. The mass of the used consumable brake lining material can be in the range of 3 kg to 20 kg per wheel and may be greater than 5 kg before replacing the consumable brake lining material. Immediately after the step of replacing the consumable brake lining material, the mass of the consumable brake lining material can be in the range of 5 kg to 25 kg per wheel, optionally greater than 10 kg and possibly in the range of 12 kg to 20 kg.

[0008] The aircraft braking mechanism may include a stator-rotor arrangement. At least a portion of the consumable brake lining material of the wheel may form part of the stator and / or rotor in the stator-rotor arrangement. For example, the rotor and / or stator may be lined with brake material. The braking force may be applied to the wheel by pushing the stator-rotor arrangement together. This may be caused by the activation of a brake actuator. The wheel may be configured such that the consumable brake lining material of the wheel forms only a part of the aircraft braking mechanism for the wheel. Other parts of the aircraft braking mechanism may be provided at locations other than on the wheel. For example, the brake actuator may be mounted on an upper member of the landing gear structure, such as on a landing gear structural member adjacent to the wheel. A housing associated with the brake (e.g., a brake actuator housing) may be mounted on a landing gear structural member.

[0009] The consumable brake lining material that is part of the wheel itself may not have sufficient heat capacity to meet the requirements of a Maximum Energy Rejected Take-Off (MERTO). This may result in a reduction in the mass of the brake material on the wheel, but may thus require additional brake material at other locations on the aircraft. Additional brake lining material may be provided on the braking mechanism or a part of the braking mechanism mounted on a landing gear structural member adjacent to the wheel. The additional brake lining material may be configured to meet the MERTO requirements by whether it is combined with the consumable brake lining material provided as part of the wheel. The additional brake lining material may have different maintenance intervals. For example, while the brake material on the wheel may need to undergo frequent routine maintenance in synchronization with the retreading / replacement of the tire, the brake material provided to meet the MERTO requirements may rarely need maintenance and / or may only need maintenance after a MERTO event. The additional brake lining material may be larger, having a greater mass and / or volume compared to the mass and / or volume of the consumable brake lining material provided as part of the wheel, preferably greater than 150% of the mass and / or volume of the consumable brake lining material provided as part of the wheel.

[0010] The consumable brake lining material that is part of the wheel may be configured to have sufficient heat capacity (e.g., given the thermal characteristics of the wheel and / or the rest of the braking device) to meet the requirements of a maximum energy rejected take-off. When the wheel is used on the aircraft, substantially all of the brake lining material required to provide braking to the wheel may be provided as part of the wheel. This may be achieved by fully integrating the brake kit into the wheel structural member. It should be understood that such a brake kit may be removably fixed in the wheel to allow for routine maintenance. The brake kit is mounted in the wheel such that when the wheel is removed from the axle of the landing gear, the brake kit integrated into the wheel is also removed. The wheel may have internal structural members that assist in fixing at least a portion of the integrated brake kit.

[0011] In certain embodiments of the present invention, the consumable brake lining material is directly attached to or integrally formed with the surface of the wheel body. For example, the outward-facing, preferably substantially flat surface of the wheel may be lined with or formed from the brake material.

[0012] The wheel typically has a hub arranged to rotate about a wheel axis and a rim connected to the hub by a structural member. The rim is shaped and configured to receive a tire, and the structural member located between the hub and the rim extends radially between the hub and the rim. There may be a first end structural member extending radially from the hub and a second end structural member extending radially from the hub, the second end structural member being spaced from the first end structural member in a direction along the wheel axis. In this case, the tire, when mounted on the wheel, occupies at least a portion of the space between the first end structural member and the second end structural member. At least some of the consumable brake lining material may be attached to the outward-facing surface of one or both of the first end structural member and the second end structural member.

[0013] The consumable brake lining material in or on the wheel may be flat (i.e., planar) for more than two-thirds of the surface area it covers (or alternatively for most of the surface area it covers). Preferably, such consumable brake lining material is substantially flat on its outward-facing surface for substantially the entire surface area it covers. In the case where the brake material is directly disposed on the surface of the wheel and there is a well-defined boundary between the brake material and the wheel, it is preferred that most (optionally more than two-thirds and possibly substantially the entire) of the surface defined by the boundary is substantially flat. It will be understood that there may be some areas of the wheel and / or the brake material that are not strictly flat, for example to allow the brake material to be keyed into the wheel surface. In this case, the outward-facing shape of the aircraft wheel will have a significantly different appearance from that of a conventional aircraft wheel shape in order to provide the dual function of the wheel and the supporting brake material.

[0014] It will be understood that the body of the wheel includes a hub, a rim, and a structural member connecting the rim to the hub. The body of the wheel typically does not include any nuts, bolts, inserts, hub caps, etc. The wheel or a part of the wheel, such as the body, can be made of a composite material. For example, most of the volume of the material making up the body of the wheel can be a composite material. Such a composite material can be in the form of a carbon fiber composite material, such as CFRP (carbon fiber reinforced polymer). Alternatively, most of the volume of the material making up the body of the wheel can be an aluminum alloy material, such as a lightweight aluminum alloy material suitable for aerospace applications. The main structure of the wheel can be made of a small number (e.g., one or two) of monolithic components. For example, at least 75% (optionally, substantially the entire volume) of the volume of the body of the wheel can be formed by one or two monolithic wheel parts. The main structure of the wheel can be in the form of a single monolithic carbon fiber wheel body.

[0015] According to a second aspect of the present invention, there is also provided an aircraft wheel and brake assembly. The aircraft wheel and brake assembly may be configured or adapted for use in the method of the first aspect of the present invention claimed or described herein. The wheel may be provided with or without a tyre. The aircraft wheel and brake assembly may include a first part and a second part, the first and second parts being configured such that the first part of the brake assembly is provided as part of the wheel and the second part of the brake assembly is provided for mounting on a landing gear structural member adjacent to the wheel. In such a case, the first part may be operable, for example, separable from the second part, to provide braking and dissipate energy at a first level. Both the first and second parts may additionally operate together to provide braking and dissipate energy at a second level, the second level being higher than the first level. For example, the first part can operate during normal braking demands, while the first and second parts can meet the demands of a MERTO event, such an event requiring braking beyond the level that the first part can provide alone. The first part of the brake assembly may be lighter than the second part of the brake assembly. The first part of the brake assembly may have a consumable brake lining material of a first mass, the mass being, for example, at least 1 kg (optionally greater than 5 kg). The second part of the brake assembly may have a consumable brake lining material of a second mass, the second mass being greater than the first mass, for example, greater than 150% of the first mass. The aircraft wheel and brake assembly may be arranged to apply braking in response to a received braking demand such that when the braking demand is below a first threshold level, the first part applies braking to the wheel and the second part does not apply braking to the wheel or applies a lower level of braking. It may be possible that when the braking demand is greater than a second threshold level and the second threshold level is equal to or higher than the first threshold level, the first part applies braking to the wheel and the second part applies more braking to the wheel. For example, when the braking demand is below the first threshold level, the first part applies braking to the wheel but the second part does not apply braking to the wheel, and when the braking demand is above the same threshold level (i.e., the second threshold level is equal to the first threshold level), both the first and second parts apply braking to the wheel. A device may be provided that transmits pressure in a manner that actuates the second part of the brake assembly when the braking pressure is above a threshold, and in a manner that actuates the first part rather than the second part of the brake assembly when below the threshold. A pressure transmission mechanism may be provided to achieve this function or a similar function. The pressure transmission mechanism may be at least partially provided as part of the second part. The first part may include at least one stator and at least one rotor. The second part may include at least one stator and at least one rotor. The rotors and stators of the first and second parts may be arranged in series. The first and second parts of the brake assembly may be arranged to be enabled by the same actuator.

[0016] According to a third aspect of the present invention, there is provided a method of braking in response to a rejected take-off of an aircraft. Such a method may include using a wheel and brake assembly as claimed or described herein. The method includes applying brakes to wheels on the landing gear of the aircraft using a brake kit that forms an integrated part of the wheel and a brake kit that is mounted on the landing gear but does not form an integrated part of the wheel. It will be understood that the brake kit that forms an integrated part of the wheel is configured such that when the wheel is removed from the landing gear, the brake kit remains part of the wheel, while the brake kit on the landing gear remains on the landing gear when the wheel is so removed. The brake kit that forms part of the wheel can be inspected while the tyre of the wheel undergoes routine maintenance, while the brake kit on the landing gear will typically be inspected in situ. The first brake kit may have less brake material than the second brake kit. The first brake kit and the second brake kit may be arranged such that braking of the wheel is provided only by the first brake kit (i.e., the first brake assembly is enabled and the second brake assembly is disabled).

[0017] According to a fourth aspect of the present invention, there is provided an aircraft wheel that includes a consumable brake lining material that is directly attached to or integrally formed with an outward-facing surface of the wheel. For example, the consumable brake lining material may be located on an outward-facing surface of an end structural member of the wheel, where the end structural members are those that extend radially outward from the hub and the tyre is located between the end structural members. The brake material may be on one or both of the outward-facing surfaces of the two end structural members of the wheel. The aircraft wheel and the integrated brake lining material may be provided with an integrated brake assembly structure, or a braking force may be applied to the wheel by frictionally engaging with the brake lining material on the wheel. At least a portion of the wheel, such as a majority (optionally, substantially all) of the wheel body, may be provided in only one or two monolithic parts. The brake material attached to or forming part of the wheel may be directly mechanically attached to the body of the wheel.

[0018] According to a fifth aspect of the present invention, there is provided an aircraft wheel and brake assembly, wherein the brake assembly includes a first part and a second part that are positioned and configured such that the wheel is directly disposed between the first part and the second part. For example, the first part may include at least one of a brake material disk and a disk-shaped pressure plate. The second part may include a brake material disk. Braking of the wheel can be achieved by pushing the first part towards the second part to directly cause braking friction between the wheel and at least the second part. In an embodiment of the present invention, at least one of the brake material disks is directly attached to or integrally formed with an outward-facing surface of the body of the wheel.

[0019] The present invention also provides an aircraft landing gear assembly and / or an aircraft, the aircraft landing gear assembly and / or the aircraft including a wheel and an associated braking assembly as described or claimed herein. The aircraft may be a commercial airliner, for example an aircraft capable of carrying more than fifty passengers, such as more than one hundred passengers. The aircraft may be a single-aisle aircraft. Certain embodiments of the present invention have specific applications related to aircraft having a maximum take-off weight (MTOW) of less than 140 tons, optionally less than 120 tons and possibly less than 100 tons. Such aircraft may generally have a low enough MTOW such that the weight of the aircraft can be supported by only three landing gears each carrying two wheels, typically a nose landing gear and two symmetrically arranged main landing gears. For example, such a six-wheel arrangement can be found on the Airbus A320 aircraft.

[0020] Of course, it should be understood that features described with respect to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the present invention may incorporate any of the features described with reference to the apparatus of the present invention, and the apparatus of the present invention may also incorporate any of the features described with reference to the method of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic diagrams, in which:

[0022] Figure 1 is a side view of an aircraft including a wheel located on a main landing gear according to a first embodiment of the present invention.

[0023] Figure 2 is a cross-sectional side view (omitting the tire) of the wheel of the first embodiment.

[0024] Figure 3 is Figure 2 a cross-sectional side view of the wheel of, but showing two separated parts of the wheel.

[0025] Figure 4 is a flow chart representing the steps of a maintenance method performed with respect to the first embodiment of the present invention.

[0026] Figure 5 is a cross-sectional side view of a wheel according to a second embodiment of the present invention.

[0027] Figure 6 is Figure 5 a cross-sectional side view of the wheel of, but showing two separated parts of the wheel.

[0028] Figures 7 to 9 shows the wheel according to the second embodiment during various braking / non-braking states.

[0029] Figure 10 is a cross-sectional side view of a wheel according to a third embodiment of the present invention.

[0030] Figure 11 is Figure 10 a partial exploded perspective view of the wheel; and

[0031] Figure 12 is a cross-sectional side view of a wheel according to a third embodiment of the present invention. Detailed Embodiment

[0032] The first embodiment of the present invention relates to a method of performing routine maintenance on the wheels of the main landing gear of an aircraft. As will now be described with reference to Figures 1 to 3 each of the wheels is equipped with its own integrated braking kit. Figure 1 shows an aircraft 10 having a nose landing gear 12 and two main landing gears 14 (only one main landing gear 14 is visible in Figure 1 ). Each main landing gear 14 includes two wheels 16, one of the two wheels 16 being shown in cross-section in Figure 2 . The aircraft thus has a total of six wheels. Figure 2 The wheel 16 of Figure 1 includes a rim 18 on which a tire is mounted (the tire is shown in Figure 2 but not shown in Figure 2 ). The braking kit includes a set of stators 20 and a set of interleaved rotors 22. The stators 20 are keyed to a torque tube 24 which remains stationary during wheel rotation in use. The rotors 22 are keyed to the wheel (and thus rotate with the wheel). One end of the torque tube 24 has a reaction plate 26 which is located at the end where the stators 20 and rotors 22 are arranged. A brake retaining plate 28 is provided at the opposite end to the end where the stators 20 and rotors 22 are arranged. The braking kit is arranged to provide braking to the rotating wheel by means of a brake piston 30 (equipped with a housing 32) which pushes a thrust plate 34 against the brake retaining plate 28 which in turn pushes the stators 20 and rotors 22 together against the reaction force provided by the reaction plate 26. In this case, each stator 20 is lined on both sides with a consumable brake lining material. The wheel is shown in

[0033] As Figure 3As shown, the wheel and brake assembly has two different sub-assemblies: a first sub-assembly 40 and a second sub-assembly 42. The first sub-assembly 40 is mounted on the landing gear and includes a brake piston housing 32 and a thrust plate 34. The second sub-assembly 42 is mounted on the axle and includes the wheel 16, the integrated torque tube 24 of the wheel, and the brake components (including the stator 20 and the rotor 22).

[0034] Figure 4 is a diagram according to the first embodiment for maintenance Figures 1 to 3Flowchart of process 1000 employed by the wheel shown. In the initial stage 1010, the wheel is started to be used on the aircraft, and the wheel has an integrated brake kit with a new tire and a new lining (with brake material). When used on the aircraft, all the brake lining materials required for braking the wheel are set as part of the wheel. After an interval (represented by arrow 1012) of multiple operating cycles of the aircraft wheel (each cycle including takeoff, flight, and subsequent landing), the tire is retreaded 1014 and the brake lining is inspected and updated / replaced 1016 if necessary. The number of cycles can be a set number, such as 400 cycles, or alternatively can be the number of cycles reached when the tire is sufficiently worn to require wheel replacement. This embodiment assumes the interval is 400 cycles, but it should be understood that many other maintenance intervals are possible, and when performing routine maintenance, the number of cycles need not be exactly the same between consecutive wheel replacements. The brake kit is inspected by removing the rotor and stator from the inside of the wheel / torque tube. If there is insufficient remaining brake lining, a new brake lining is replaced and / or the stator / rotor coated with sufficient brake material is replaced. After consecutive intervals 1018, 1020, 1022 of another 400 cycles, the same steps of retreading the tire 1014 and inspecting / updating the brake lining 1016 are implemented. (It can be understood that when the wheel is removed from the aircraft, it is usually replaced with a different wheel, and the wheel that has been repaired again is usually subsequently used on a different aircraft.) Thus, there is a routine maintenance procedure through which the inspection and replacement of the consumable brake lining material are synchronized with the retreading of the tire. This is achieved to some extent by increasing the inspection frequency of the brake material, which is usually only inspected every about 2000 cycles, and the inspection of the brake material is usually at a different time and / or location from the tire retreading. Due to the increased frequency of brake lining maintenance, less brake material is provided for each wheel. In this case, the quality of the initially provided brake material can be about 20 kg per wheel (compared to the usual amount of 35 kg), thus saving about 60 kg of mass (4 brake devices per aircraft). The usual wear of the brake material averages about 8 kg per 2000 cycles (during five routine maintenance cycles, less than half of the available brake material is used). The mass of the brake material used can vary according to the type of aircraft operation plan. Of course, it is generally desired to provide sufficient brake material so that there is no risk of all the brake material being used between routine maintenance intervals (assuming standard operation of the aircraft and no abnormal operations), but still reduce the mass of the brake material required / provided. Most of the consumable brake lining material may be used for at least 10% of the time (during five consecutive routine maintenance cycles).After approximately 2000 cycles (the fifth consecutive interval arrow 1024), the tire is replaced (box 1030), and a comprehensive inspection of the braking kit is carried out (box 1032). Then the cycle repeats. It is possible that the brake material is replaced approximately once in ten times (i.e., 10% of such cases), and the replacement of the brake material can occur as frequently (or not less frequently) as the tire replacement (i.e., not only retreading), and more than half of the mass of the brake material is used. Of course, depending on the geometry and shape of the brake material, this may correspond to a wear of approximately 60 mm. This wear can be judged by sampling 50 times for the event of replacing the brake material and finding at least 5 such events that correspond to having consumed more than half of the mass of the brake material.

[0035] Providing the following wheels allows reducing the mass of the brake material on the entire aircraft: compared with a conventional braking system, the wheels themselves have the mass of the brake material that is inspected more frequently. This also means that the aircraft operator does not need to frequently inspect the braking system on the aircraft - the main inspection can be carried out during the workshop maintenance of the wheels. Such an inspection can include, for example, a wear pin inspection. Thus, the operating costs can be reduced. The brakes can also be inspected each time the wheels are replaced, which can also identify problems with the brakes earlier, otherwise, if not discovered for a long time, it may lead to an operation interruption.

[0036] Figures 5 to 9 Illustrated is a wheel and an associated braking assembly according to a second embodiment. Like parts are denoted by like reference numerals with the last two digits being the same. Similar to the first embodiment, the wheel 116 is provided with its own integrated braking kit, which includes a set of stators 120 keyed to the torque tube 124 and a set of staggered rotors 122 keyed to the wheel. However, in this embodiment, the braking kit integrated with the wheel is lighter than that in the first embodiment, but is thus provided with an additional braking kit separated from the wheel. The braking kit of the wheel will be referred to as the inner braking kit, while the additional braking kit will be referred to as the outer braking kit. The outer braking kit forms part of a subassembly mounted on the landing gear. The stators 120 and rotors 122 of the inner braking kit are sandwiched between the torque tube reaction plate 126 and the brake retaining plate 128. The outer braking kit includes a pair of larger stators 150, and a single larger rotor 152 is disposed between the pair of stators. The larger stators 150 are keyed to the torque tube 124 via an intermediate structural member. The single larger rotor 152 is keyed to the wheel. The rotor-stator group of the outer braking kit is arranged between the intermediate reaction plate 156 and the thrust plate 134. The rotor-stator group of the outer braking kit is arranged in series with the rotor-stator group of the inner braking kit.

[0037] The external braking kit further includes a pressure transmission device 160, which is arranged parallel to the rotor and stator of the external braking kit. When the braking pressure is below a first threshold braking pressure applied by the brake piston 130, the compression amount of the pressure transmission device 160 can be negligible, so that the applied braking pressure is basically all transmitted to the internal braking kit. When the braking pressure is above a second higher threshold braking pressure, the pressure transmission device 160 undergoes significant compression, so that the applied braking pressure is also transmitted to the rotor and stator of the external braking kit. The internal braking kit and the external braking kit are configured such that the external braking kit is rarely used during the normal operation of the aircraft. The internal braking kit is sized to meet all normal braking requirements except for a maximum energy rejected takeoff. The braking required in the case of a maximum energy rejected takeoff needs to dissipate a large amount of heat energy, and usually a larger volume of braking material is required to handle the generated heat. The combination of the braking material of the external braking kit and the internal braking kit provides sufficient heat capacity to meet the requirements of a maximum energy rejected takeoff (MERTO). The mass of the braking material in the internal braking kit is about 8 kg, while the mass of the braking material in the external braking kit is about 15 kg (i.e., approximately twice). In this embodiment, the consumable brake lining material of the internal braking kit itself does not have sufficient heat capacity to meet the requirements of MERTO. In the first embodiment, the braking material that is part of the wheel is configured to have sufficient heat capacity to meet the requirements of MERTO. Under specific braking requirements, the internal braking kit will apply braking to the wheel, while the external braking kit will apply minimal braking if present. In the case of MERTO (i.e., under higher braking requirements), the external braking kit will apply significantly greater braking (in terms of the energy consumption rate of the braking kit) compared to the internal braking kit.

[0038] Routine maintenance of the tires and the braking material carried by the wheel itself can be carried out in a manner almost identical to the method shown in Figure 4 (since the braking material is inspected at each tire retread interval). MERTO is a rare event, and usually non-routine maintenance inspections must be carried out as soon as possible after such an event occurs. If MERTO does not occur, the regular maintenance of the external braking kit can be carried out less frequently compared to the maintenance (interval) usually adopted by a regular braking kit sized and configured for normal braking and additional braking in the case of MERTO. Given that the regular replacement / inspection of the braking material is provided as part of the routine maintenance of the internal braking kit, the replacement of the braking material on the external braking kit can be less frequent, for example.

[0039] In Figure 6Two different sub - assemblies of the second embodiment are shown. There is a first sub - assembly 140 that is mounted on the landing gear and includes an external brake kit (including a stator 150 and a rotor 152), a brake piston housing 132, and a thrust plate 134. There is also a second sub - assembly 142 that includes a wheel 116 and an internal brake kit (including a stator 120 and a rotor 122).

[0040] Now, the operation of the wheel and brake assembly will be described with reference to Figures 7 to 9 Figure Figure 7 Figure shows a situation where the actuator 130 is not applying a brake. The internal brake kit on the wheel (including the stator 120 and the rotor 122 shown in Figure 5 and Figure 6 ) is denoted by reference numeral 170. The external brake kit on the landing gear (including the stator 150 and the rotor 152 shown in Figure 5 and Figure 6 ) is denoted by reference numeral 172. In Figure 8 Figure, a normal level of braking applied by the actuator 130 is shown. In this case, the internal brake kit 170 is engaged (schematically shown by arrow 174), the pressure transfer device 160 is not actually enabled, and thus the external brake kit 172 is not enabled. During emergency braking (such as in the case of MERTO), as shown in Figure 9 Figure, an increased pressure is applied by the actuator 130. The increased pressure applied by the actuator 130 causes the pressure transfer device 160 to allow pressure to be delivered to the external brake kit 172 (schematically shown by arrow 176). Both the internal brake kit 170 and the external brake kit 172 are fully engaged.

[0041] Figure 10 and Figure 11 Figures illustrate a wheel and an associated brake assembly according to the third embodiment. Similar components are labeled with the same reference numerals having the last two digits the same. Figure 10 is a cross - sectional view, while Figure 11 is a schematic exploded view. Similar to the first embodiment, the wheel 216 is provided with its own integrated brake lining material set. However, in this embodiment, the consumable brake lining material 280 is directly attached to the surface of the wheel body, in this case on the inner side of the wheel. The wheel body itself is a monolithic carbon fiber composite structural member and can thus act as a radiator when the brake lining material 280 heats up due to friction. The wheel 216 has a hub 238 that is mounted to rotate about an axle 236 about a wheel axis (labeled A in Figure 10 Figure). Figure 10The hubcap 284 is also shown. The wheel has an outer end of the rim 218 that extends radially from the hub to the outer end, and an inner end of the rim 218 that extends radially from the hub to the inner end. A tire is mounted between the inner end and the outer end of the wheel on the rim 218 (the tire is not shown in Figure 10 ). The rim 218 is provided with a heat insulator 286 to protect the tire when the wheel gets hot. The wheel assembly includes a splined torque tube 224 that remains fixed during wheel rotation in use. Braking is provided to the rotating wheel 216 by means of a set of brake pistons 230 (mounted to the landing gear via a housing 232), which push a pressure plate 234 against a brake lining 280 formed as part of the wheel (the brake material is provided as a component of the outward-facing surface of the inner end of the wheel). The pressure plate 234 is also lined with brake material 282. It can be observed that both brake linings 280 and 282 are completely flat (i.e., the brake lining is flat for all surfaces of the wheel covered by the brake material), and the surface area of the brake linings 280 and 282 is greater than 50% of the available surface area of the flat outward-facing surface of the inner end of the wheel.

[0042] When the piston 230 is actuated, the rotating brake lining 280 and the non-rotating brake lining 282 are pressed against each other, and the force from the pressure plate 234 reacts against a disc-shaped reaction plate 226 on the outer side of the wheel. The wheel is shown in Figure 10 and Figure 11 as mounted on an axle 236. By utilizing the heat capacity of the carbon wheel as a radiator, the amount of carbon brake material required can be reduced. The mass of the carbon brake lining can be significantly reduced while still being able to provide effective braking in the event of a MERTO. All of the brake material required for 100% braking of the wheel is provided as a component of the wheel. This simplifies and synchronizes the routine maintenance procedures for the tire and the brake.

[0043] The wheel and associated brake assembly according to the fourth embodiment are illustrated by Figure 12 which can be compared and contrasted with the wheel and associated brake assembly according to the third embodiment as shown in Figure 10 . Similar components are labeled with the same reference numerals with the last two digits the same. Similar to the third embodiment, there is a consumable brake lining material 380 directly attached to the surface of the inner end structure of the carbon wheel. The main difference is that the outer end structure of the wheel is also lined with brake material 390. This increases the braking force and reduces excessive heat accumulation in any of the sets of brake discs. The brake material on the wheel is also formed by directly mechanically attaching the brake material to the body of the wheel.

[0044] The torque tube 324 has an outer reaction plate 326 at its outer end and an inner reaction plate 327 at its inner end. When braking is applied, the inner pressure plate 334, which is keyed to the torque tube and lined with brake material 392, engages a brake material disc 380 on the inner end of the wheel. When braking is applied, the outer reaction plate 326 of the torque tube 324, which is lined with brake material 394, engages a brake material disc 390 on the outer end of the wheel. Braking is provided to the rotating wheel 316 by means of a set of brake pistons 330 (mounted to the landing gear via the inner reaction plate 327 of the torque tube 324), which push the brake linings 380, 392 together and the brake linings 390, 394 together. The braking force is reacted in a closed-loop mechanical linkage provided by the end plates 326, 327 of the torque tube such that the braking force is not transmitted to the axle through the wheel as Figure 10 in the option.

[0045] The following clauses define the subject matter of the present disclosure:

[0046] Clause A. An aircraft wheel comprising

[0047] a wheel axis;

[0048] a hub;

[0049] a first end structure member extending radially from the hub, and

[0050] a second end structure member extending radially from the hub, the second end structure member being spaced from the first end structure member in a direction along the wheel axis;

[0051] at least a portion of the space between the first end structure member and the second end structure member defines an area for receiving a tire, and

[0052] a consumable brake lining material directly attached to or integrally formed with the outward-facing surface of the first end structure member.

[0053] Clause B. The aircraft wheel according to Clause A, wherein

[0054] additional consumable brake lining material is directly attached to or integrally formed with the outward-facing surface of the second end structure member.

[0055] Clause C. An aircraft wheel and brake assembly, wherein the brake assembly includes a first part and a second part, the first part includes at least one of a brake material disc and a disc-shaped pressure plate, the second part includes a brake material disc, and the body of the wheel is disposed between the first part and the second part of the brake assembly.

[0056] Clause D. The aircraft wheel and brake assembly according to Clause C, wherein at least one of the brake material discs is directly attached to or integrally formed with the outward-facing surface of the body of the wheel.

[0057] Clause E. An aircraft wheel and brake assembly including an aircraft wheel according to Clause A or Clause B.

[0058] Clause F. The aircraft wheel and brake assembly according to Clause D or Clause E, wherein the brake material attached to the outward-facing surface is flat so as to cover more than half of the surface area.

[0059] Clause G. The aircraft wheel and brake assembly according to any one of Clauses C to F, wherein most of the volume of the material forming the body of the wheel is a composite material.

[0060] Clause H. The aircraft wheel and brake assembly according to Clause G, wherein the composite material is a carbon fiber composite material.

[0061] Clause I. The aircraft wheel and brake assembly according to any one of Clauses C to F, wherein most of the volume of the material forming the body of the wheel is an aluminum alloy material.

[0062] Clause J. The aircraft wheel and brake assembly according to any one of Clauses C to I, wherein at least 75% of the volume of the body of the wheel is formed by one or two monolithic wheel parts (e.g., as a radiator during braking).

[0063] Clause K. The aircraft wheel and brake assembly according to Clause J, wherein the body of the wheel is formed as a single monolithic structural member.

[0064] Although the invention has been described and illustrated with reference to specific embodiments, those of ordinary skill in the art will understand that the invention is applicable to many different variations that are not specifically illustrated herein. Certain possible variations will now be described, which are for example only.

[0065] More braking material can be provided within the wheel, which means that the brake lining does not need to be replaced every time the tire is changed / refurbished. Such a design does not significantly reduce the mass, but still saves time because the brake inspection, which is part of the routine maintenance of the tire, can be carried out in the workshop (instead of having to perform the brake inspection when the brake assembly is in the position on the aircraft landing gear as is conventional in the art).

[0066] Some of the rotors in the brake kit can be provided with braking material. The stators may not be lined with braking material at all.

[0067] Figures 10 to 12 The wheel body can be formed by two monolithic parts (two-part wheel body). Directly attached to Figure 10 and Figure 11 The brake lining material of the wheel body can be integrally formed with the wheel body. The brake lining material can be directly mechanically attached to the surface of the wheel body.

[0068] The function of the above-mentioned pressure transmission device can be performed by means of a compressible member, which is arranged to be compressed in a substantially linear manner. The pressure transmission device is compressed in a direction parallel to the wheel axis and parallel to the axes of the rotor and stator under the action of a hydraulic brake actuator. The pressure transmission device effectively includes two push plates: an inner push plate and an outer push plate. In the non-activated state, the inner push plate is positioned directly adjacent to the inner brake kit, while the outer push plate is set to face away from the outer brake kit. When any non-negligible braking pressure is applied, the inner push plate pushes against the inner brake kit, which provides normal braking. As the pressure increases, the inner push plate continues to push against the inner brake kit, while the outer push plate gradually approaches the outer brake kit. At a certain braking pressure threshold, the outer push plate will contact and start to push against the outer brake kit, so that combined braking by means of both the inner brake kit and the outer brake kit begins. Alternatively, the pressure transmission device can be a simple spring-type mechanism, which gradually engages the outer brake kit as the braking pressure increases, so as to perform combined braking by means of the inner brake kit and the outer brake kit before an emergency braking requirement.

[0069] In the foregoing description, when referring to a whole or an element having known, obvious or foreseeable equivalents, then these equivalents are incorporated herein as if set forth separately. The true scope of the present invention should be determined with reference to the claims, and the true scope of the present invention should be construed as covering any such equivalent forms. The reader will also realize that the wholes or features of the present invention described as being preferred, advantageous, convenient, etc. are optional and do not limit the scope of the independent claims. In addition, it should be understood that although these optional wholes or features may be beneficial in some embodiments of the present invention, they may be undesirable in other embodiments and may therefore be absent.

[0070] Unless the context otherwise requires, the term "or" shall be construed as "and / or".

Claims

1. An aircraft landing gear assembly, the aircraft landing gear assembly including a braking assembly and a wheel, the braking assembly including a first part and a second part, the first part and the second part being configured such that the first part of the braking assembly is a first braking kit and the second part of the braking assembly is a second braking kit, the first braking kit including one or more rotors and one or more stators and being provided as an integral part of the wheel, the second braking kit including one or more rotors and one or more stators and being provided for mounting on a landing gear structural member adjacent to the wheel, and the second braking kit not forming an integral part of the wheel, The first part is operable independently of the second part so as to provide braking and dissipate energy at a first level, Both the first part and the second part are operable together so as to provide braking and dissipate energy at a second level, the second level being higher than the first level, and The rotor-stator set of the first braking kit is arranged in series with the rotor-stator set of the second braking kit.

2. The aircraft landing gear assembly according to claim 1, wherein, The first part of the braking assembly has a consumable brake lining material of a first mass, the mass being at least 1 kg, and the second part of the braking assembly has a consumable brake lining material of a second mass, the second mass being greater than the first mass.

3. The aircraft landing gear assembly according to claim 1, wherein, The braking assembly is arranged to apply braking in response to a received braking demand such that at a first threshold level below the braking demand, the first part applies braking to the wheel, but the second part either does not apply braking to the wheel or applies braking at a lower level, and such that at a second threshold level above the braking demand, the first part applies braking to the wheel and the second part applies greater braking to the wheel, the second threshold level being equal to or higher than the first threshold level.

4. The aircraft landing gear assembly according to claim 3, wherein, The second part is configured to apply braking to the wheel in the case of a maximum energy interrupted takeoff.

5. The aircraft landing gear assembly according to claim 1, wherein, The first part and the second part of the braking assembly are arranged to be actuated by the same actuator.

6. The aircraft landing gear assembly according to claim 5, wherein, The same actuator is configured to enable the braking provided by the first part of the braking assembly via a compressible pressure transfer device that compresses above a threshold pressure in a manner that actuates the second part of the braking assembly.

7. The aircraft landing gear assembly according to claim 2, wherein, The heat capacity of the consumable brake lining material of the first part that is part of the wheel is insufficient to meet the requirements of a maximum energy interrupted takeoff.

8. The aircraft landing gear assembly according to claim 2 or 7, wherein, The consumable brake lining material of the second part for mounting on a landing gear structural member adjacent to the wheel is configured to meet the requirements of the maximum energy interrupted takeoff.

9. The aircraft landing gear assembly according to claim 2, wherein, The consumable brake lining material of the first part is directly attached to or integrally formed with the surface of the body of the wheel.

10. The aircraft landing gear assembly according to claim 2, wherein, The wheel has: a wheel axis, a hub, a first end structure member radially extending from the hub, and A second end structure member extending radially from the hub, the second end structure member being spaced apart from the first end structure member in a direction along the wheel axis, and a tire, the tire occupying at least a portion of the space between the first end structure member and the second end structure member, and wherein at least some of the consumable brake lining material of the first portion is attached to the outward-facing surface of the first end structure member.

11. The aircraft landing gear assembly according to claim 10, wherein at least some of the consumable brake lining material of the first portion is attached to the outward-facing surface of the second end structure member.

12. The aircraft landing gear assembly according to claim 10, wherein, The consumable brake lining material attached to the outward-facing surface of the wheel is flat for covering more than two-thirds of the surface area of the surface.

13. The aircraft landing gear assembly according to claim 1, wherein, Most of the volume of the material for manufacturing the body of the wheel is aluminum alloy material or carbon fiber composite material.

14. The aircraft landing gear assembly according to claim 10, wherein, Most of the volume of the material forming the body of the wheel is carbon fiber composite material.

15. The aircraft landing gear assembly according to claim 1 or 14, wherein, At least 75% of the volume of the body of the wheel is formed by one or two monolithic wheel parts.

16. A braking method in response to a rejected takeoff of an aircraft, the braking method comprising applying brakes to the wheel by using a first braking kit that forms an integrated part of the wheel on the landing gear of the aircraft and by using a second braking kit that is mounted on the landing gear but does not form an integrated part of the wheel, Among them, the first braking kit includes one or more rotors and one or more stators, the second braking kit includes one or more rotors and one or more stators, wherein the first braking kit can operate independently of the second braking kit to provide braking and dissipate energy at a first level, both the first braking kit and the second braking kit can operate together to provide braking and dissipate energy at a second level, the second level being higher than the first level, and the rotor-stator set of the first braking kit is arranged in series with the rotor-stator set of the second braking kit.

17. The braking method according to claim 16, wherein, The first braking kit has less braking material than the second braking kit.

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