Brake monitoring device

Abstract

Apparatus and methods are disclosed for determining a thermal oxidation state of a brake of an aircraft landing gear. Determining the thermal oxidation state of the brake includes determining the thermal oxidation state of the brake after a braking event based on an initial thermal oxidation state prior to the braking event and a temperature profile of the brake as a function of time using a thermal oxidation model.

Description

TECHNICAL FIELD

[0001] The present invention relates to determining thermal oxidation of brakes of an aircraft landing gear. BACKGROUND

[0002] When an aircraft is parked on the ground between flights, the brakes of the aircraft landing gear are typically inspected. In particular, the amount of wear of the brakes and the thermal oxidation of the brakes can be inspected and maintenance or replacement of the brakes can be performed or scheduled based on the inspection. SUMMARY

[0003] A first aspect of the present invention provides an apparatus for determining a thermal oxidation state of a brake of an aircraft landing gear, the apparatus comprising a processor configured to determine, using a thermal oxidation model, a thermal oxidation state of the brake after a braking event based on an initial thermal oxidation state before the braking event and a temperature profile of the brake over time.

[0004] Optionally, the initial thermal oxidation state is updated using the determined thermal oxidation state after the braking event and the processor is configured to determine a thermal oxidation state after a subsequent braking event based on the updated initial thermal oxidation state. In an example, using the determined thermal oxidation state after the braking event can mean that the initial thermal oxidation state is updated to be equal to or approximately equal to the determined thermal oxidation state after the braking event. In other examples, the initial thermal oxidation state can be made equal to a function of the determined thermal oxidation state after the braking event (e.g. the initial thermal oxidation state can be made equal to the determined thermal oxidation state multiplied by a factor of 1.05 so as to include a 5% margin, other factors and margins can alternatively be used).

[0005] Optionally, the temperature profile of the brake is for a usage cycle of the aircraft and the processor is configured to determine a respective updated thermal oxidation state after each braking event within the usage cycle of the aircraft.

[0006] Optionally, the processor is configured to determine an amount of wear of the brake caused by the braking event using a brake wear model based on an amount of energy absorbed by the brake as a result of the braking event and a density parameter of the brake.

[0007] Optionally, the processor is configured to determine the density parameter of the brake based on the initial thermal oxidation state before the braking event.

[0008] Optionally, the processor is configured to: (i) predict a future heat oxidation state and a future brake wear amount after a predicted future usage cycle; and (ii) if one of the heat oxidation threshold and the brake wear threshold is reached, determine a number of good future usage cycles, otherwise repeat (i) and (ii) for a next predicted future usage cycle, wherein: each predicted future usage cycle comprises a plurality of braking events; and for each predicted future usage cycle, the prediction is made based on a respective predicted temperature profile of the brake, the current heat oxidation state, a predicted amount of energy absorbed by the brake during the respective braking event, and a respective predicted density parameter of the brake for the respective braking event.

[0009] Optionally, the processor is configured to predict a future brake wear amount after a second plurality of predicted future usage cycles, wherein the second plurality of future usage cycles is a plurality of cycles after which the brake wear threshold is substantially reached; each predicted future usage cycle comprises a plurality of braking events; and for each predicted future usage cycle, the prediction is made based on a predicted amount of energy absorbed by the brake during the respective braking event and a respective predicted density parameter of the brake for the respective braking event.

[0010] Optionally, the processor is configured to predict a future heat oxidation state after a first plurality of predicted future usage cycles, wherein the first plurality of future usage cycles is a plurality of cycles after which the heat oxidation threshold is reached; each predicted future usage cycle comprises a plurality of braking events; and for each predicted future usage cycle, the prediction is made based on a respective predicted temperature profile of the brake and the current heat oxidation state.

[0011] Optionally, the processor is configured to determine the heat oxidation state after the braking event based on the high temperature interval, the initial heat oxidation state, and a heat oxidation rate parameter using a heat oxidation model.

[0012] Optionally, the processor is configured to: compare the temperature profile to a set of temperature criteria; and if one or more criteria from the set of temperature criteria is met, identify a high temperature event corresponding to the braking event based on the comparison, and determine a time interval occupied by the high temperature event as the high temperature interval.

[0013] Optionally, the processor is configured to: determine a high temperature event value for the high temperature interval; and determine an oxidation rate parameter based on the determined temperature value and physical characteristic information of the brake.

[0014] Optionally, the processor is configured to select the heat oxidation model based on the initial heat oxidation state.

[0015] A second aspect of the application provides a method for determining a thermal oxidation state of a brake of an aircraft landing gear, the method comprising: inputting a temperature profile of the brake as a function of time and an initial thermal oxidation state of the brake prior to a braking event; and determining a thermal oxidation state of the brake after the braking event using a thermal oxidation model based on the initial thermal oxidation state and the temperature profile.

[0016] Optionally, the method according to the second aspect comprises: updating the initial thermal oxidation state using the determined thermal oxidation state after the braking event; and determining a thermal oxidation state after a subsequent braking event based on the updated initial thermal oxidation state. In an example, using the determined thermal oxidation state after the braking event can mean updating the initial thermal oxidation state to be equal or approximately equal to the determined thermal oxidation state after the braking event. In other examples, the initial thermal oxidation state can be made equal to a function of the determined thermal oxidation state after the braking event (e.g. the initial thermal oxidation state can be made equal to the determined thermal oxidation state multiplied by a factor of 1.05 so as to include a 5% margin in the calculation, other factors and margins can alternatively be used).

[0017] Optionally, the method according to the second aspect comprises: determining an amount of brake wear caused by the braking event using a brake wear model based on an amount of energy absorbed by the brake as a result of the braking event and a density parameter of the brake.

[0018] Optionally, the method according to the second aspect comprises: (i) predicting a future thermal oxidation state and a future amount of brake wear after a predicted future cycle of use; (ii) if one of a thermal oxidation threshold and a brake wear threshold is reached, determining a number of good future cycles of use, otherwise repeating (i) and (ii) for a next predicted future cycle of use, wherein: each predicted future cycle of use comprises a plurality of braking events; and for each predicted future cycle of use, the prediction is made based on a respective predicted temperature profile of the brake, the current thermal oxidation state, a predicted amount of energy absorbed by the brake during the respective braking events, and a respective predicted density parameter of the brake for the respective braking events.

[0019] A third aspect of the application provides an apparatus for determining a thermal oxidation level of a brake of an aircraft landing gear, the apparatus comprising a processor configured to determine an updated thermal oxidation level of the brake after a braking event using a thermal oxidation evolution model of the brake based on an initial thermal oxidation level prior to the braking event and temperature data of the brake as a function of time. BRIEF DESCRIPTION OF DRAWINGS

[0020] Embodiments of the present application will now be described, by way of example only, with reference to the accompanying drawings in which:

[0021] Figure 1 is a schematic diagram of an aircraft on which examples can be deployed;

[0022] Figure 2 is a schematic diagram of a brake and wheel of an aircraft landing gear according to an example;

[0023] Figure 3 is a flowchart of a first example method of determining a thermal oxidation state of a brake of an aircraft landing gear;

[0024] Figure 4 is a flowchart of a second example method of determining a thermal oxidation state of a brake of an aircraft landing gear;

[0025] Figure 5 is a plot illustrating a temperature of a brake against time;

[0026] Figure 6 is a plot illustrating a thermal oxidation state of a brake against time for a particular temperature;

[0027] Figure 7 is a flowchart of a method of determining an amount of wear of a brake according to an example;

[0028] Figure 8 is a flowchart of a method of predicting a number of good future use cycles in relation to an aircraft brake according to an example; and

[0029] Figure 9 is a schematic diagram of a computing device. DETAILED DESCRIPTION

[0030] Figure 1 is a simplified schematic diagram of an aircraft 100. The aircraft 100 comprises a plurality of landing gear assemblies 102. Each landing gear assembly 102 comprises a brake assembly for providing braking when the aircraft 100 is on the ground. The aircraft 100 comprises a computing system 104 which may, for example, comprise one or more processors and one or more computer-readable storage media. The aircraft 100 can also comprise instruments 106, such as measurement instruments for measuring characteristics or parameters in relation to the aircraft, and instruments for measuring environmental characteristics. The aircraft 100 can also comprise indication devices 108 for providing various indications in relation to the aircraft, examples of which will be described herein. The indication devices can comprise screens to display text and / or graphics, dials, light indicators, sound indicators to emit a sound to provide an indication, and the like.

[0031] Figure 2 is a simplified schematic of an aircraft brake assembly 200 of the landing gear assembly 102. In this example, the brake assembly 200 includes a plurality of brake discs 202 including a pressure plate 204, a reaction plate 206, and a plurality of rotors and stators such as rotor 208 and stator 210. In this example, the brake discs 202 include a plurality of rotors and stators, and thus, the brake assembly 200 is a multi-disc brake. In other examples, the brake assembly 200 can not be a multi-disc brake. In Figure 2 , the brake assembly 200 is shown as being associated with a wheel 214 of the landing gear assembly 102. It will be understood that the type of brake used in an aircraft landing gear depends on the characteristics of the aircraft in question, such as size, carrying capacity, etc., and there can be more than one wheel associated with any one landing gear assembly.

[0032] When the aircraft 100 supported by the landing gear assembly 102 is travelling along the ground, the rotors rotate with the wheel 214, while the stators, pressure plate 202 and reaction plate 204 do not rotate with the wheel 214. When braking is applied, the pressure plate 204 is forced towards the reaction plate 206 so that the brake discs 202 begin to contact each other (as shown in block 216 of Figure 2 ) and frictional forces act to inhibit the rotational action of the rotors, resulting in a braking force.

[0033] Any one or more of the rotors, stators, pressure plate 204 and reaction plate 206 can comprise carbon-carbon (CC) composite material. A brake comprising brake discs with CC composite material can be referred to as a carbon brake. For example, the brake discs 202 can comprise a graphite matrix reinforced with carbon fibres. The methods disclosed herein can be suitable for any type of brake that uses CC composite material or carbon ceramic as a friction material for braking. Examples include racing car brakes (e.g. Formula One racing car brakes), other high performance automotive brakes. The methods disclosed herein can also be suitable for other industrial applications of CC composite material or carbon ceramic, for example applications where lubrication of the components is more important than friction.

[0034] To monitor the temperature of the brake discs 202, a temperature sensor 212 can be provided. For example, the temperature sensor 212 can be provided in thermal contact with the brake disc that is likely or known to reach the highest temperature during braking. In Figure 2In the example of FIG. 2, a temperature sensor 212 is disposed on the stator 210. The temperature sensor 212 can be any type of temperature sensor suitable for use in an aircraft brake assembly. For example, the temperature sensor 212 can be capable of functioning properly at a temperature range that the brake disc 202 can reach. For example, the temperature sensor 212 can be a thermocouple, a surface acoustic wave (SAW) sensor, an eddy current sensor, a thermal resistance sensor, a strain gauge, or the like.

[0035] The temperature sensor 212 can measure the temperature of the stator 210 at a given measurement interval, for example, during a period of time when the brake assembly 200 is expected to be used. The length of the given measurement interval can vary, for example. The given measurement interval can be regular, irregular, or regular for one period of time and irregular for another period of time. For example, the temperature sensor 212 can measure the temperature such that a temperature profile of the stator 210 as a function of time is captured. In other words, the temperature sensor 212 measures the temperature of the stator 210 at a given measurement interval such that temperature information as a function of time is captured. For example, a processor of the computing system 104 can control the operation of the temperature sensor 212 based on instructions stored in a computer-readable storage medium of the computing system 104. The temperature measurements captured by the temperature sensor 212 can be stored in the storage medium of the computing system 104, for example, along with associated time data.

[0036] During use of the brake assembly 200, the CC composite material of the brake disc 202 can oxidize. More specifically, during a brake application, the brake disc 202 can oxidize thermally due to the brake disc 202 reaching high temperatures for a significant period of time. A measure of thermal oxidation can be proportional to, for example, a mass loss of the brake due to thermal oxidation. During a thermal oxidation reaction, oxygen and carbon of the brake disc 202 react with each other, causing carbon atoms to be removed from the brake disc 202 due to the generation of carbon dioxide and / or carbon monoxide. Thus, a thermal oxidation state of the brake, which can also be referred to as a thermal oxidation level, can be expressed as an amount of mass loss due to thermal oxidation. Thermal oxidation of the CC composite material of the brake disc 202 can occur, for example, at temperatures above 400°C. In addition, for example, wear of the brake disc 202 can occur due to friction during braking. After a period of use, the brake assembly 200 or components thereof can require repair or replacement. Typically, aspects of the aircraft brakes are inspected by ground crew personnel when the aircraft, such as the aircraft 100, is on the ground. The ground crew personnel can determine, through individual visual inspection, whether the brake assembly 200 is in a condition suitable for further use or whether repair or replacement is required. If it is determined that repair or replacement with respect to the brake assembly 200 is required at a time other than a time scheduled for repair or similar treatment, the aircraft 100 to which the brake assembly 200 belongs can be "grounded" until the repair or replacement is performed. Here, the term "grounded" means that the aircraft 100 is not allowed to fly, for example, while carrying passengers. Such inspection by ground crew personnel ensures safe operation of the aircraft 100.

[0037] Figure 3 A method 300 of determining a thermal oxidation state of a brake, such as the brake assembly 200, of the aircraft landing gear assembly 102 according to embodiments of the present application is summarized. The method 300 includes determining a thermal oxidation state of the brake assembly 200 after a brake event based on an initial thermal oxidation state, which can also be referred to as an initial thermal oxidation level, prior to the brake event and a temperature profile of the brake with respect to time using a thermal oxidation model. The determined thermal oxidation state of the brake assembly 200 after the brake event can be referred to as an updated thermal oxidation state. This is because the thermal oxidation state of the brake assembly 200 after the brake event takes into account a change in the initial thermal oxidation state due to the brake event.

[0038] A braking event is an event related to an application of the brake assembly 200. For example, a braking event can include one or more applications of the brake assembly 200 to slow or stop the aircraft 100. In some examples, a braking event can be a portion of time during which the brake assembly 200 is continuously applied. Whenever the brake assembly 200 is applied, the temperature of the brake assembly 200 can increase. This is because when the brake assembly 200 is applied to reduce the speed of the aircraft 100, some kinetic energy of the aircraft 100 is absorbed into the brake assembly 200 as heat, causing the temperature of the brake assembly 200 to increase. Thus, it can be determined whether the brake assembly 200 has been applied based on changes in the temperature of the brake assembly 200.

[0039] At block 302 of the method 300, a temperature profile of the brake assembly 200 and an initial thermal oxidation state are input. As explained above, the temperature profile represents a change in temperature over time. The input temperature profile may, for example, be related to a usage cycle of the aircraft 100. For example, the temperature profile can be for an entire usage cycle of the aircraft 100, such as from a time when the aircraft 100 is at a departure gate before a flight to a time when the aircraft 100 is at an arrival gate after a flight. In particular, the temperature profile can indicate a change in temperature over time for all braking events that occur during one cycle. In other examples, the temperature profile can not be for an entire usage cycle of the aircraft 100. For example, the temperature profile can be for a single braking event, or a portion of a cycle with multiple braking events. In some examples, multiple temperature profiles belonging to a particular usage cycle can be used to determine a thermal oxidation state of the brake assembly 200 after the usage cycle.

[0040] The temperature profile may, for example, be related to a usage cycle that has already occurred. In other words, the temperature profile can include actual data from the temperature sensor 212 of the aircraft 100 during a previous usage cycle. In such examples, the temperature profile is related to actual data. On the other hand, in some examples, the temperature profile can be a predicted temperature profile for a predicted future usage cycle of the aircraft 100. In this case, the braking events can be predicted future braking events.

[0041] The initial thermal oxidation state of the brake assembly 200 is the thermal oxidation state of the brake assembly 200 prior to the braking event for which the updated thermal oxidation state is determined. For example, for a new brake assembly 200 installed in the aircraft 100, the initial oxidation state can represent no oxidation. In some examples, the initial oxidation state of a newly installed brake assembly 200 can be set by aircraft maintenance personnel at the time of installation and can represent no oxidation or some oxidation assessed by the personnel performing the installation. In examples where the brake assembly 200 is not new, the initial oxidation state can be the oxidation state calculated at a previous instance of the method 300 being performed. In some examples, a non-new brake or brake component can be installed on the aircraft 100. If temperature profile information for all previous braking events involving the brake or brake component is available, the thermal oxidation state at the time of installation can be determined using the method 300 or by other methods disclosed herein utilizing the available temperature profile information.

[0042] At block 304 of the method 300, the thermal oxidation state after the braking event (the updated thermal oxidation state) is determined using a thermal oxidation model. For example, the thermal oxidation model is applied based on the input temperature profile and the initial thermal oxidation state of the brake assembly 200. The thermal oxidation model, for example, indicates how the thermal oxidation state is expected to change over time within various temperature ranges starting from the initial thermal oxidation state. The thermal oxidation model is a model of the thermal oxidation evolution of the brake. Which thermal oxidation model is used can depend, for example, on the initial thermal oxidation state. Details and selection of suitable thermal oxidation models will be further described below. In some examples, the method 300 can be performed in real-time during a usage cycle of the aircraft 100. Where the method 300 is performed in real-time (i.e., in real-time or near real-time), the temperature profile used can be, for example, from temperature data obtained by the temperature sensor 212 up to that point. Thus, at block 304, what is determined is how the oxidation state changes from the initial oxidation state due to the temperature rise associated with the braking event in question.

[0043] After the updated thermal oxidation state has been determined, the initial thermal oxidation state can be set to the updated thermal oxidation state. In this way, the initial thermal oxidation state is kept up to date with all previous braking events. In examples where the temperature profile relates to more than one braking event, the method 300 can be performed again to determine an updated thermal oxidation state after a subsequent braking event. Updating the initial thermal oxidation state in this way can ensure that the initial thermal oxidation state used for the subsequent braking event takes into account all previous braking events.

[0044] In the example where the temperature profile is for the entire usage cycle of the aircraft 100, the method 300 can be performed to determine a respective updated thermal oxidation state after each braking event within the usage cycle. It will be understood that the process can be performed sequentially with respect to the chronological order of the braking events. This makes the determination of the updated thermal oxidation state for each of the braking events a starting point (initial thermal oxidation state) that takes into account all previous braking events.

[0045] In the method 300, the updated thermal oxidation state after a braking event can be determined based on the high temperature interval, the initial thermal oxidation state, and the thermal oxidation rate parameter, for example, with a suitable thermal oxidation model.

[0046] Figure 4 is a flowchart of a method 400 that illustrates actions that can be performed as part of the method 300. For example, the method 400 relates to a more specific example of block 304 of the method 300. Block 402 is the same as block 302 of the method 300 in that the temperature profile of the brake with respect to time and the initial thermal oxidation state of the brake assembly 200 are input. At block 404, the temperature profile is compared to a set of temperature criteria. The set of temperature criteria can include a set of temperature thresholds. For example, the set of temperature criteria can include a first temperature threshold of 400°C and a second temperature threshold of 750°C. In other examples, different temperature thresholds can be used depending on the physical characteristics of the brake assembly 200. The comparison of the temperature profile can be performed sequentially, for example, in the chronological order of the temperature data contained in the temperature profile. For example, a temperature value can be compared to the set of temperature thresholds and subsequently, the next real-time temperature value can be compared to the set of temperature thresholds.

[0047] At box 406, it is determined whether one or more temperature criteria are met. If, for example, no temperature threshold is exceeded, method 400 ends. It will be understood that the thermal oxidation of the CC composite material of the brake disc 202 is a relatively long process at high temperatures. Therefore, the comparison of the temperature profile with this set of temperature thresholds indicates a high-temperature event corresponding to a braking event that may lead to thermal oxidation. As mentioned above, a braking event is, for example, the application of the brake assembly 200. However, a high-temperature event is an event in which the temperature of the brake assembly exceeds at least one of the temperature thresholds due to the braking event. For example, if the temperature of the brake assembly 200 remains below all temperature thresholds during the braking event (i.e., braking application), a high-temperature event will not occur during that braking event. On the other hand, if the temperature of the brake assembly exceeds one temperature threshold during the braking event, the portion of the braking event exceeding the temperature threshold can be referred to as a high-temperature event. If more than one temperature threshold is exceeded, a high-temperature event may be the portion of the braking event exceeding the highest temperature threshold.

[0048] The temperature thresholds can be set based on temperatures above which significant thermal oxidation is expected. Therefore, method 400 terminates if none of the temperature thresholds are exceeded. This is because, in this example, no braking event occurs at a sufficiently high temperature to cause thermal oxidation. In this example, the updated thermal oxidation state after the braking event can simply be set to the initial thermal oxidation state before the braking event in question.

[0049] On the other hand, if at least one of the temperature thresholds is exceeded, a high-temperature event corresponding to the braking event discussed is identified at block 408 of method 400. The high-temperature event corresponds to the portion of the temperature curve that exceeds the highest exceeded temperature threshold. This is because the portion of the temperature curve that exceeds the highest exceeded threshold corresponds to the portion of the braking event that exceeds the highest temperature threshold. (See also...) Figure 5 The identification of high-temperature events is described. Figure 5 This is a graph illustrating a portion of an example temperature curve. Figure 5 In the graph, the vertical axis represents the temperature of the brake assembly 200, and the horizontal axis represents time. In this example, curve portion 502 represents the point where the temperature of the brake assembly 200 exceeds a first temperature threshold 504 and a second temperature threshold 506. In this example, a high-temperature event is identified as the portion of curve 502 above the second temperature threshold 506, because the second temperature threshold 506 is the highest temperature threshold exceeded.

[0050] For a given time interval, the amount of thermal oxidation occurring above the second temperature threshold 506 can be significantly greater than thermal oxidation above the first temperature threshold 504 but below the second temperature threshold 506. Thus, in this example, the portion of the temperature profile below the second temperature threshold 506 is not considered. In other examples, such as when the method 400 is used for real-time oxidation state monitoring as will be further described below, the portion of the temperature profile between the two temperature thresholds can be considered. It will be appreciated that, Figure 5 The graph of FIG. 4 is merely an illustration of an example for purposes of explanation.

[0051] At block 410, the time interval occupied by the high temperature event is determined as a high temperature interval. As noted above, the updated thermal oxidation state can be determined based on the high temperature interval, among other factors. In the example of FIG. 4, Figure 5 In the example of FIG. 4, the high temperature interval is determined as the time interval 508.

[0052] At block 412, a high temperature event value for the brake assembly 200 is determined for the high temperature interval. The high temperature event value is a value of the temperature reached as a result of the high temperature event. In some examples, the high temperature event value is an average temperature during the high temperature interval. Alternatives to the high temperature event value as an average temperature in the context of real-time oxidation monitoring are described below.

[0053] At block 414, an oxidation rate parameter is calculated based on the high temperature event value and physical property information for the brake. For example, the oxidation rate parameter for the thermal oxidation reaction can be determined based on the Arrhenius equation shown as Equation 1 below:

[0054]

[0055] In Equation 1, k(T) is the thermal oxidation rate, A is a pre-exponential factor, E A is the activation energy of carbon atoms of the CC composite component of the brake assembly 200, R is the universal gas constant and T is the temperature. In this example, for a particular high temperature event, the temperature T in Equation 1 is set to the high temperature event value for purposes of block 414. In this example, the thermal oxidation rate k(T) is the oxidation parameter determined at block 414. The value of the activation energy E A and the pre-exponential factor A can depend on the physical properties of the CC composite component of the brake assembly 200 (in this example, the brake disc 202). For example, the values of these parameters can depend on the density, porosity, manufacturing process, contaminants present in the CC composite structure, surface finish of the components, and surface coating of the brake assembly 200. The activation energy E Aand the pre-exponential factor A can also depend on the high temperature event value and the initial thermal oxidation state. Thus, in order to determine the oxidation parameters, the activation energy E A Suitable values of the activation energy E

[0056] For example, the activation energy E A may be inversely proportional to the temperature. The activation energy E A may become lower at temperatures at which oxygen molecules are able to penetrate the surface of the brake disc 202 and oxidation of carbon deeper in the brake disc 202 can occur. The activation energy E A Suitable values of the activation energy E

[0057] Figure 6 is a graph of an example of the evolution of the thermal oxidation of the brake disc of the brake assembly 200 for a particular temperature over time. Figure 6 The vertical axis of the graph in represents a measure of the thermal oxidation, which is represented by the thermal oxidation state Ox. For example, the thermal oxidation state Ox can be proportional to the mass loss of the brake assembly 200 due to thermal oxidation of the brake disc 202. The evolution curve 602 shows how the ratio of the mass loss due to thermal oxidation at a particular temperature changes over time. It should be noted that different evolution curves would represent the change of the thermal oxidation state Ox over time for different temperature values.

[0058] In this example, the thermal oxidation state Ox changes over time below the thermal oxidation state level 604 in a different way than it changes above the thermal oxidation state level 604. In this example, the thermal oxidation state Ox (i.e. the mass loss due to thermal oxidation) is shown to increase non-linearly over time below the oxidation state level 604 and to change approximately linearly over time above the oxidation state level 604. In this example, the thermal oxidation state increases at an accelerating rate over time before the thermal oxidation state level 604 is reached. After the thermal oxidation state level 604 has been reached, the rate of change of the thermal oxidation state Ox over time remains approximately constant. Figure 6 The part of the graph of below the thermal oxidation state level 604 can for example be considered a first thermal oxidation region, i.e. region 1, and Figure 6 The part of the graph of above the thermal oxidation state level 604 can for example be considered a second thermal oxidation region, i.e. region 2.

[0059] In some examples, different values of the activation energy E and the pre-exponential factor A can be used depending on which thermal oxidation zone the brake assembly 200 is in as indicated by the initial thermal oxidation state A .

[0060] At block 416, a thermal oxidation model is selected based on the initial thermal oxidation state prior to the braking event. The thermal oxidation model describes the evolution of the thermal oxidation state Ox of the brake assembly 200 for different temperature values. When the initial thermal oxidation state is in zone 1, a thermal oxidation model can be selected that describes the evolution of the thermal oxidation state Ox in zone 1. When the initial thermal oxidation state is in zone 2, a thermal oxidation model can be selected that describes the evolution of the thermal oxidation state Ox in zone 2. For example, a first thermal oxidation model, model 1, can be selected for zone 1, and a second thermal oxidation model, model 2, can be selected for zone 2. Model 1 for zone 1, which describes a non-linear change of the thermal oxidation state Ox over time, can be represented by equation 2. Model 2 for zone 2, which describes a linear change of the thermal oxidation state Ox over time, can be represented by equation 3 below.

[0061] Ox = 1 - [1 - {k(T) x t eq (1 - n)} 1 / 1-n ] (2)

[0062] Ox = k(T) x t eq (3)

[0063] In equations 2 and 3 above, k(T) is the thermal oxidation rate defined by equation 1. The parameter t eq is an equivalent time, which is the time it would take at temperature T to reach the thermal oxidation state Ox. The parameter n refers to the order of the equation and the parameter n depends on the properties of the CC composite material used in the brake assembly 200. The parameter n can be determined experimentally, for example, for a brake using a particular CC composite material.

[0064] In some examples, different thermal oxidation models than the ones described by equations 2 and 3 can be used. In some examples, a single thermal oxidation model can be used that describes the evolution of the thermal oxidation state Ox for all thermal oxidation states Ox related to the brake assembly 200. In some examples, more than two thermal oxidation models can be used for respective ranges of thermal oxidation states Ox. The method 400 can be modified as appropriate to utilize such alternative thermal oxidation models. For example, a different set of inputs can be applied to the thermal oxidation model as appropriate than the ones described in this particular example of the method 400.

[0065] It will be appreciated that once block 402 has been executed, block 416 can be executed at any stage of method 400, as block 416 requires the initial thermal oxidation state.

[0066] At block 418, the updated thermal oxidation state for the high temperature event is determined using a selected thermal oxidation model based on the high temperature interval, the initial thermal oxidation state, and the determined thermal oxidation rate parameter. For example, the thermal oxidation model determines the time from zero to the initial thermal oxidation state at the high temperature value, and adds the high temperature interval to the time to determine the value of t eq from the selected thermal oxidation model. The value of t eq determined therefrom and the thermal oxidation parameter are input into the equation selected from equations 2 and 3 above to yield as output the updated thermal oxidation state of brake assembly 200 after the high temperature event.

[0067] The updated thermal oxidation state can be set as a new initial thermal oxidation state for subsequent use in method 400 for subsequent high temperature events in the temperature profile.

[0068] In some examples, method 300 and / or method 400 can be performed in real time during a use cycle in which a brake event occurs. In such examples, for example, a portion of method 400 can be modified to allow for real time brake oxidation monitoring, and the temperature profile can correspond to real time measured temperature values. For example, the temperature information provided by temperature sensor 212 can be continuously compared to the set of temperature criteria according to block 404 of method 400, and a high temperature event can be identified as it occurs. It will be appreciated that even though this type of oxidation state monitoring is described as being real time, the extent to which this type of oxidation state monitoring is performed in real time will depend on various hardware and software (e.g., processing speed) limitations. For example, there can be a time delay between the temperature values measured by temperature sensor 212 corresponding to a high temperature event, and these values ultimately yield an updated thermal oxidation state of brake assembly 200.

[0069] For example, a high temperature event can be identified as a smaller portion of a temperature profile than the examples described above. Again with reference to Figure 5A portion of the curve portion 502 occurring within a time interval denoted by 510 can be considered a high temperature event, and the interval 510 can be considered a high temperature interval. In this example, the high temperature event value can be considered, for example, the temperature value measured at the beginning or end of the high temperature interval 510, or an average of the two temperature values. Unlike the example above, in the case of real-time monitoring, portions of the temperature curve between the first and second temperature thresholds can be taken into account even when the temperature exceeds the second temperature threshold 506. In the case of real-time monitoring, any portion of the temperature curve above at least one of the temperature thresholds, such as the portion denoted by interval 510, can be identified as a high temperature event. It will be understood that this modification can allow the thermal oxidation state of the brake assembly 200 to be updated as high temperature events corresponding to brake events are occurring. In some examples, a high temperature event can be identified based on a time between subsequent temperature measurements obtained by the temperature sensor 212. For example, the interval 510 can be a time interval between subsequent temperature measurements obtained by the temperature sensor 212.

[0070] The method 300 and the method 400 can be used to determine the thermal oxidation state of the brake assembly 200 after an actual usage cycle of the aircraft 100 or in real-time during the actual usage cycle. In such examples, this can be done based on one or more temperature curves encompassing brake events within the usage cycle. As mentioned above, in some examples, the thermal oxidation state of the brake assembly 200 in relation to an actual usage cycle that has already occurred is determined using temperature curve information collected by the temperature sensor 214.

[0071] On the other hand, in some examples, the method 300 or the method 400 can be used to predict a future thermal oxidation state of the brake assembly 200 after a first plurality of predicted future usage cycles of the aircraft 100. The first plurality of future usage cycles can be a plurality of cycles after which a thermal oxidation threshold is reached. Each predicted future usage cycle can include a respective plurality of brake events. For each predicted future usage cycle, the prediction can be made based on a respective predicted temperature curve of the brake assembly 200 and a current thermal oxidation state. The current thermal oxidation state is, for example, an oxidation state taking into account all previous brake events experienced by the brake assembly 200.

[0072] For example, a predicted temperature profile can be input into the method 300 or method 400, for example in a time sequence, to determine a future thermal oxidation state of the brake assembly 200. This predicted temperature profile, which predicts a future usage cycle, can be predicted based on a previous temperature profile for a previous actual usage cycle of the aircraft 100. For example, a portion of the previous temperature profile that is related to a landing phase can be utilized to predict a landing phase portion of the temperature profile for the future usage cycle. The high temperature intervals, high temperature event values, etc. can be stored in a computer-readable storage medium for purposes of predicting the future thermal oxidation state when the method 300 or method 400 is performed for an actual usage cycle of the aircraft 100.

[0073] In some examples, data from previous cycles can not be available, for example because the brake assembly 200 can be new. In some examples, there can not be enough data available to reliably predict a temperature profile for a predicted future usage cycle. In such examples, a predetermined temperature profile can be used. The predetermined temperature profile can be a profile that is generally expected for future usage cycles of the aircraft 100.

[0074] The predicted temperature profile can take into account, for example, a future flight plan of the aircraft 100. For example, the aircraft 100 can be expected to land at an aircraft field that has a short runway, thereby requiring high energy (i.e., high temperature) braking at landing for some of the predicted future usage cycles of the aircraft. For those predicted future usage cycles, the predicted temperature profile can indicate high energy braking at landing. It will be understood that various other factors can be taken into account when predicting the temperature profile, such as taxi times at various phases of the predicted future usage cycle, wait times between taxi phases and previous landing phases, etc.

[0075] As mentioned above, the first plurality of predicted future use cycles can be a plurality of predicted future use cycles after which a predicted future thermal oxidation state reaches a thermal oxidation threshold. For example, predictions of future thermal oxidation state can cease after a cycle in which the thermal oxidation threshold is reached. In some examples, predictions of future thermal oxidation state can cease as soon as the thermal oxidation threshold is reached. The thermal oxidation threshold can be an oxidation state at which the brake assembly 200 or a component of the brake assembly 200 requires repair or replacement. For example, the brake assembly 200 can require repair when the mass of the brake assembly has been reduced by between 4% and 6.5%, for example by 5.7%, where the selected percentage threshold can vary, for example, depending on the density of the original manufactured disc. In this example, the first plurality of predicted future use cycles is the number of cycles in which the proportion of mass loss due to thermal oxidation reaches or exceeds, for example, 5.7% (i.e. within the range of 4% to 6.5%).

[0076] On the other hand, in some examples, predictions of future thermal oxidation state can cease at the end of one predicted future use cycle during which the future thermal oxidation state is nearly close to the thermal oxidation threshold, such that the future thermal oxidation state can be expected to reach the thermal oxidation threshold during the next predicted future use cycle. In such examples, the thermal oxidation threshold can be considered to have been reached within the first plurality of predicted future use cycles. This is because, in practice, an aircraft 100 having a brake assembly 200 that is expected to reach the thermal oxidation threshold in the next cycle in a strict sense would not be allowed to fly, and repair or replacement in relation to the brake assembly 200 can be carried out at this time.

[0077] With the first plurality of predicted future use cycles, an indication can be given as to how many use cycles can occur before the brake assembly 200 or a component of the brake assembly 200 requires repair or replacement due to thermal oxidation. In examples in which the thermal oxidation threshold is reached or exceeded strictly during the last of the first plurality of future cycles, the number of cycles before repair or replacement due to thermal oxidation can be predicted to be one less than the number of cycles in the first plurality of future cycles. In examples in which predictions of future thermal oxidation state cease when the thermal oxidation threshold is expected to be reached in the next cycle after the first plurality of future cycles, the number of the first plurality of future cycles is considered to be the number of cycles before repair and replacement due to thermal oxidation.

[0078] Figure 7is a flowchart of a method 700 that utilizes a brake wear model to determine an amount of brake wear caused by a braking event based on an amount of energy absorbed by a brake assembly 200 due to the braking event and a density parameter of the brake assembly 200. The amount of brake wear can be determined for all braking events in which energy is input into the brake assembly 200 in a process that involves friction that will cause surface wear of a brake disc. For example, the wear of a brake disc due to friction can cause a length (L shown) of the brake disc 202 to decrease as the brake disc material is lost due to the friction. Figure 2

[0079] For example, the amount of brake wear can be determined for those braking events that do not involve any high-temperature events. For the method 700, a braking event can be identified as an event in which the temperature of the brake assembly 200 increases, for example, based on a temperature profile. In some examples, a braking event can simply be identified based on an indication that the brake assembly 200 has been applied. For example, the computing system 104 of the aircraft 100 can detect when the brake assembly 200 is applied and when it is released.

[0080] At block 702 of the method 700, an amount of energy input into the brake assembly 200 during a braking event is determined. The amount of energy input into the brake assembly 200 can be determined during the braking event based on characteristics of the aircraft, such as a mass of the aircraft 100, a speed of the aircraft 100 during the braking event, and the like, for example. The amount of energy absorbed by the brake assembly 200 can be calculated based on such characteristics of the aircraft 100 by determining the kinetic energy of the aircraft 100. For example, a proportion of the kinetic energy of the aircraft 100 can be absorbed by the brake assembly 200 to reduce the kinetic energy of the aircraft 100. In some examples, the amount of energy input into the brake assembly 200 can be determined based on measurements obtained by the instruments 106 of the aircraft 100. For example, the instruments 106 can include a tachometer associated with a wheel 214 associated with the brake assembly 200. In such an example, the tachometer measures a rotational speed of the wheel 214, and the amount of energy absorbed by the brake assembly 200 can be determined using a change in the rotational speed over time.

[0081] In other examples, if the mass of the brake assembly 200 is known, the amount of energy absorbed can be determined based on an increase in the temperature of the brake assembly 200 and accounting for the specific heat of the brake assembly 200. In some examples, the mass of the brake assembly 200 can be determined based on the thermal oxidation state of the brake assembly 200 determined according to the method described above, as the thermal oxidation state can be represented as an amount of mass loss of the brake assembly 200 due to thermal oxidation, as described above.

[0082] ​At block 704 of the method 700, a density parameter of the brake assembly 200 is determined. The density parameter is, for example, a parameter that indicates that the density of the brake assembly 200 has decreased compared to an original density and takes into account a loss of mass. The density of the brake assembly 200 can have decreased, for example, due to thermal oxidation. It will be appreciated that thermal oxidation results in a loss of mass because carbon atoms react with oxygen to form carbon dioxide or carbon monoxide and thus carbon atoms are removed from the brake disc 202. However, thermal oxidation can not necessarily change the volume of the brake disc 202. This is because thermal oxidation can act non-uniformly on specific surfaces of the brake disc and can proceed to a certain depth inside the brake disc.

[0083] The density parameter can be represented as (1 - Ox), where the thermal oxidation state Ox is represented as a number between 0 and 1. For example, the density of the brake assembly 200 has decreased by a factor of (1 - Ox) compared to an initial density before thermal oxidation occurred (i.e., when the brake assembly 200 was new). Thus, the density parameter can be determined based on an initial oxidation state before a braking event.

[0084] In some examples, the decreased density of the brake assembly 200 can be determined based on measurements taken by an instrument included in the instrument 106. For example, the mass of the brake assembly 200 can be calculated based on the amount of energy absorbed by the brake assembly 200 (e.g., based on measurements from a tachometer) and a subsequent temperature increase of the brake assembly 200 (e.g., based on measurements from the temperature sensor 212). The decreased density of the brake assembly 200 can be determined based on the calculated mass of the brake assembly 200. The aircraft 100 can include a wear pin associated with the brake assembly 200. Typically, the wear pin provides an indication of a decrease in the length L of the brake and thus an indication of brake wear. The wear pin can be, for example, inspected between cycles by ground crew and an updated volume value of the brake assembly 200 can be obtained. In some examples, there can be other ways to measure changes in the length L of the brake assembly 200. For example, a length sensor can be provided to the brake assembly 200 and / or an electrically actuated brake can be used. The updated volume value can be determined based on the decreased length L and can be used to determine the decreased density from the mass. During a single cycle, the change in volume of the brake assembly 200 can be insignificant for the purposes of calculating the density parameter, and the updated volume can be obtained after multiple cycles. The density parameter can be determined from the decreased density.

[0085] At block 706 of the method 700, the amount of brake wear caused by the brake event is determined using a brake wear model based on the energy absorbed by the brake assembly 200 and the density parameter from block 704. For example, the mass loss due to wear by the brake assembly 200 during the wear event is determined using the brake wear model of equation 4 below:

[0086]

[0087] In equation 4 above, m 磨损 is the mass loss due to wear during the brake event, E 制动器 is the energy absorbed by the brake assembly 200, and W, X, Y, and Z are constants. The constants W, X, Y, and Z can be pre-determined, for example, through experimentation, and the constants W, X, Y, and Z can vary depending on the characteristics of the brake assembly 200. The amount of brake wear for the brake event can be determined as a reduction in the length L of the brake assembly 200 based on the amount of mass reduction due to brake wear during the brake event.

[0088] As mentioned above, in some examples, the initial thermal oxidation rate is used to determine the density parameter. In these examples, when a brake event occurs in which a high temperature event also occurs during the brake event, the initial thermal oxidation state can be used for the determination of block 706. This is because the time period in which brake wear occurs is shorter than the time period in which thermal oxidation occurs.

[0089] The amount of brake wear determined for the brake event can be added to the amount of brake wear from all previous brake events of the brake assembly 200 in order to determine the total amount of brake wear.

[0090] Method 700 can be executed in real time, for example, during a period of time when a braking event occurs, or in real time with respect to a usage cycle that has already occurred, utilizing relevant data from that usage cycle. Method 700 can also be used to predict the future brake wear of the brake assembly 200 after a second plurality of predicted future usage cycles of the aircraft 100. The second plurality of predicted future usage cycles can be a plurality of cycles after which a brake wear threshold is reached. Each predicted future usage cycle can include a corresponding plurality of braking events. For example, method 700 can be executed for each braking event within the second plurality of predicted future usage cycles. The wear amount of each braking event can be summed to predict the future brake wear of the second plurality of predicted future usage cycles. For each predicted future usage cycle, the prediction can be based on the predicted amount of energy absorbed by the brake during the corresponding braking event and the corresponding predicted density parameter of the brake for the corresponding braking event. For example, a braking event can be identified, and the energy absorbed by the brake assembly 200 for that braking event can be determined based on a predicted temperature profile. In other examples, the predicted amount of absorbed energy can be based on data from previous cycles. If the brake assembly 200 is new or there is not enough prior data available, the predicted amount of energy can be determined in advance.

[0091] For the purpose of predicting future brake wear, method 700 can be used in conjunction with method 300 or method 400. In these examples, only the most recent initial thermal oxidation state prior to each predicted braking event (e.g., a predicted future braking event) is known. In this way, the mass of brake assembly 200 can be determined using the initial thermal oxidation state prior to the future braking event in question, and therefore, the density parameter can be determined using the initial thermal oxidation state prior to the future braking event in question.

[0092] As mentioned above, the second plurality of predicted future use cycles can be a plurality of predicted future cycles after which the predicted future brake wear amount reaches a brake wear threshold. For example, the prediction of future brake wear amount can stop after a cycle that reaches the brake wear threshold. In some examples, the prediction of future brake wear amount can stop as soon as the total brake wear amount reaches the brake wear threshold. The brake wear threshold can be the total amount of brake wear when brake assembly 200 or a component of brake assembly 200 requires maintenance or replacement. For example, the brake assembly, such as Figure 2The brake assembly 200 in the example of FIG. 1 can require servicing if its length L has been reduced, for example, by 22% to 24% from the density of the disc according to the type of disc and the original manufacture of the disc. For an exemplary disc having an original length L of approximately 221 mm, a reduction in length of approximately 50 mm can result in servicing or replacement. In this example, the second plurality of predicted future usage cycles is the number of cycles (again, for an original disc having a length L of approximately 221 mm) that the brake assembly 200 occupies for a total brake wear amount to reach or exceed, for example, 50 mm.

[0093] On the other hand, in some examples, the prediction of future brake wear can stop at the end of one predicted future usage cycle during which the total brake wear amount is nearly approaching the brake wear threshold, such that the total brake wear amount can be expected to reach the brake wear threshold during the next predicted future usage cycle. In such an example, the brake wear threshold can be considered to be reached within the second plurality of predicted future usage cycles. This is because, in practice, an aircraft 100 having a brake assembly 200 that is expected to reach the brake wear threshold in the next cycle in the strict sense would not be allowed to fly, and servicing or replacement related to the brake assembly 200 can be performed at that time.

[0094] With the second plurality of predicted future usage cycles, an indication can be given as to how many usage cycles can occur before the brake assembly 200 or components of the brake assembly 200 need to be serviced or replaced due to brake wear. In examples in which the brake wear threshold is strictly reached or exceeded during the last of the second plurality of future cycles, the number of cycles before servicing or replacement due to brake wear can be predicted to be one less than the number of cycles in the second plurality of future cycles. In examples in which the prediction of future brake wear is stopped when the brake wear threshold is expected to be reached in the next cycle after the second plurality of future cycles, the number of the second plurality of future cycles is considered to be the number of cycles before servicing and replacement due to brake wear.

[0095] Figure 8is a flowchart of a method 800 for determining a number of good future use cycles before one of a thermal oxidation threshold and a brake wear threshold is reached. The number of good future use cycles is a remaining number of future use cycles before one of the thermal oxidation threshold or the brake wear threshold is reached. The method 800 can be performed for a plurality of predicted future use cycles until the thermal oxidation threshold of the thresholds is reached. The method 800 comprises predicting a future thermal oxidation state and a future brake wear amount after a predicted future use cycle, and if one of the thermal oxidation threshold and the brake wear threshold is reached, determining a number of good future use cycles before any of the thresholds is reached. If one of the thresholds is not reached, the prediction is performed for a next predicted future use cycle. As in the example above, each predicted future use cycle comprises a plurality of braking events. For each predicted future use cycle, the prediction is based on a respective predicted temperature profile of the brake, the current thermal oxidation state, a predicted amount of energy absorbed by the brake during the respective braking events, and a respective predicted density parameter of the brake for the respective braking events.

[0096] The number of good future use cycles is a number of cycles after which a repair or replacement of the brake assembly 200 or components of the brake assembly 200 is needed. It will be understood that the repair or replacement related to the brake assembly 200 can be performed when one of the thermal oxidation threshold or the brake wear threshold is first reached. Which threshold is reached first can for example depend on the way the aircraft 100 is maneuvered during use and the flight plan of the aircraft. For example, if the plan of the aircraft 100 involves mainly flying to airports with long runways, short taxi paths, etc., it can be that the brake wear threshold is reached first. This is because the temperatures of the brake assembly 200 can typically not exceed any of the temperature thresholds related to thermal oxidation in this example. On the other hand, the aircraft 100 can typically experience high energy braking (e.g. due to short runways), resulting in temperatures above the thresholds related to thermal oxidation. In this example, it can be that the thermal oxidation threshold is reached first.

[0097] At block 802 of the method 800, a future thermal oxidation state after a predicted future use cycle is predicted. The prediction of this future thermal oxidation state is performed in a manner as described above, for example based on the predicted temperature profile of the predicted future use cycle in question, using a suitable thermal oxidation model. At block 804 of the method 800, a future brake wear amount after the same predicted future use cycle is predicted. This prediction is performed as described above in the part of the method 700.

[0098] At block 806 of the method 800, it is determined whether the thermal oxidation threshold and / or the brake wear threshold is reached. For example, if the thermal oxidation threshold is reached, the method 800 continues to block 808 where a number of good future usage cycles before either the thermal oxidation threshold or the brake wear threshold is reached is determined, and the method 800 ends. For example, if the thermal oxidation threshold is strictly reached or exceeded after a given number of predicted future usage cycles, the number of good future usage cycles is one less than the given number. For example, if the thermal oxidation threshold is expected to be reached in the next predicted future usage cycle, the number of good future usage cycles is determined to be the number of predicted future usage cycles that the method 800 has performed so far.

[0099] On the other hand, if it is determined that the brake wear threshold is reached, the method continues to block 808 where the number of good future usage cycles is determined, and the method 800 ends. For example, if the brake wear threshold is strictly reached or exceeded after a given number of predicted future usage cycles, the number of good future usage cycles is one less than the given number. For example, if the brake wear threshold is expected to be reached in the next predicted future usage cycle, the number of good future usage cycles is determined to be the number of predicted future usage cycles that the method 800 has performed so far.

[0100] If, for example, both of the thresholds are reached, the method 800 continues to block 808 where the number of remaining good future usage cycles before either the thermal oxidation threshold is reached or the brake wear threshold is reached is determined, and the method 800 ends. In this example, if at least one of the thresholds is strictly reached or exceeded after a given number of predicted future usage cycles, the number of good future usage cycles is one less than the given number. Otherwise, the number of good future usage cycles is determined to be the number of predicted future usage cycles that the method 800 has performed so far.

[0101] If the brake wear threshold is not reached, the method 800 continues to block 810, and blocks 802-810 are repeated for the next predicted future usage cycle.

[0102] In this way, the number of good future usage cycles can be predicted based on which of the thermal oxidation threshold or the brake wear threshold is first reached. This is because: once the thermal oxidation threshold of the thresholds is reached, the brake assembly 200 can need to be serviced or replaced, or a component of the brake assembly 200 can need to be serviced or replaced. For example, it will be appreciated that if the thermal oxidation threshold is reached but the brake wear threshold is not reached, then the brake assembly 200 will not continue to be used. It will also be appreciated that the blocks in the method 800 can be performed in any suitable order. For example, block 804 can be performed before block 802, and / or block 810 can be performed before block 806.

[0103] One or more of the above-described methods - i.e. the method 300, the method 400, the method 700, and the method 800 - or any of the variants of the above-described methods (e.g. real-time determination of oxidation or brake wear, or prediction of future thermal oxidation state or future brake wear, etc.) can be performed by the processor of the computing system 104 of the aircraft 100, e.g. based on instructions stored in a computer-readable storage medium of the computing system 104. For example, monitoring of the thermal oxidation state (after a usage cycle or in real-time) can be performed by the processor of the computing system 104. Alternatively, or in addition, monitoring of the brake wear (after a usage cycle or in real-time) can be performed by the processor of the computing system. Alternatively, or in addition to any of these examples, prediction relating to future thermal oxidation state and / or future brake wear state can be performed by the processor of the computing system 104. The method can be performed, e.g. using data from the instrumentation 106. For example, temperature data measured by the temperature sensor 212 can be utilised. In the case of making a prediction, future temperature profiles and / or other prediction data can be predicted by the processor of the computing system 104. Alternatively, data for the prediction can be determined on a computing system that is not on-board the aircraft 100 and can be stored in a computer-readable storage medium of the computing system 104.

[0104] The indication device 108 of the aircraft 100 can be used to provide indications to the pilot and / or ground crew regarding the thermal oxidation state, the brake wear amount, the number of cycles before the thermal oxidation threshold is reached, the number of cycles before the brake wear threshold is reached, and / or the number of good future use cycles. For example, these indications can allow the ground crew to assess aspects of the brake assembly 200 in a more rapid manner than a visual inspection or other physical inspection alone. These indications can also allow for proper scheduling of maintenance and replacement related to the brake assembly 200. This can prevent delays due to each time the aircraft 100 is grounded without scheduling of maintenance or replacement, as the ground crew determines issues with the brake assembly 200 that can not have been known earlier without making predictions related to thermal oxidation and / or brake wear.

[0105] Indications to the pilot related to thermal oxidation and / or brake wear can, for example, assist the pilot in indicating to the ground crew when maintenance or replacement related to the brake assembly 200 can be needed. Indications of the state of the brake assembly 200 for previous cycles can also assist the pilot of the aircraft 100 in assessing the pilot’s brake application behavior. For example, the indications can show that a particular change in brake behavior can result in less thermal oxidation per cycle and a greater number of good future use cycles. This can occur, for example, in a situation in which the thermal oxidation threshold is predicted to be reached first. When one or more of the above-described methods are being performed in real-time by the processor of the computing system 104, the indications related to thermal oxidation and / or brake wear of the brake assembly 200 can allow the pilot to make substantial adjustments to brake application behavior in real-time in order to protect the brake assembly 200. For example, the pilot can not immediately begin taxiing the aircraft 100 after a high-energy landing that allowed for a high-energy landing, such that the temperature of the brake assembly 200 does not remain above the temperature threshold related to thermal oxidation.

[0106] One or more of the above-described methods, i.e., the method 300, the method 400, the method 700, and the method 800, or any variation of the above-described methods (e.g., making real-time determinations of oxidation or brake wear, or making predictions of future thermal oxidation states or future brake wear, etc.) can be performed by a computing device, such as, for example Figure 9The computing device 900 can be external to the aircraft 100. The computing device 900 can include a processor 902 and a computer-readable storage medium 904. The processor 902 can be configured to execute instructions stored on the storage medium 904. The storage medium 904 can store instructions for performing all or part of any of the methods described above. Data such as temperature profile information can be provided to the computing device 900 for use in performing the methods disclosed herein. In the case of real-time monitoring, data from the aircraft can be transmitted to the computing device 900. For example, any of the methods described above can be performed by the computing device 900 and the resulting indications reported to personnel responsible for the maintenance and / or use of the aircraft 100.

[0107] All or part of the instructions for performing the methods described above can be generated using any suitable software or combination of software, and / or the methods can be performed using any suitable software or combination of software. In one example, "MATLAB" can be used to generate all or part of the instructions for a processor, such as the processor 902, or a processor of the computing system 104, to perform any of the methods described above. In other examples, other software packages can be used. For example, any suitable programming language, development environment, software package, etc. can be used. Other examples of programming languages include PYTHON, C++, C, JAVASCRIPT, FORTRAN, etc.

[0108] It will be appreciated that the methods disclosed herein allow for monitoring of the thermal oxidation state and / or brake wear state (either in real-time or after a cycle of use). The methods also allow for making predictions related to future thermal oxidation state and brake wear of the brake assembly 200.

[0109] It should be noted that the term "or" as used herein is to be interpreted as "and / or", unless expressly stated otherwise. Although the present application has been described with reference to one or more preferred embodiments, it will be understood that various changes and modifications can be suggested by those skilled in the art without departing from the scope of the application as defined in the appended claims.

Claims

1. An apparatus for determining the thermal oxidation state of a brake on an aircraft landing gear, the apparatus comprising: A processor configured to determine the thermal oxidation state of the brake after the predicted future braking event using a thermal oxidation model based on the initial thermal oxidation state prior to the predicted future braking event and the brake's predicted temperature profile over time.

2. The device according to claim 1, wherein, The initial thermal oxidation state is updated using the determined thermal oxidation state following the predicted future braking event; and The processor is configured to determine the thermal oxidation state after a subsequently predicted future braking event based on the updated initial thermal oxidation state.

3. The device according to claim 2, wherein, The predicted temperature profile of the brake is used for the predicted future use cycle of the aircraft, and the processor is configured to determine the corresponding updated thermal oxidation state after each predicted future braking event within the predicted future use cycle of the aircraft.

4. The device according to any of the preceding claims, wherein, The processor is configured to use a brake wear model to determine the amount of brake wear caused by the predicted future braking event based on the amount of energy absorbed by the brake due to the predicted future braking event and the density parameter of the brake.

5. The device according to claim 4, wherein, The processor is configured to determine the density parameter of the brake based on the initial thermal oxidation state prior to the predicted future braking event.

6. The device according to claim 4 or claim 5, wherein, The processor is configured to: (i) Predicting the future thermal oxidation state and future brake wear after predicted future use cycles; and (ii) If either the thermal oxidation threshold or the brake wear threshold is reached, then determine the number of good future use cycles; otherwise, repeat (i) and (ii) for the next predicted future use cycle. in, Each predicted future uses a loop that includes multiple predicted future braking events; and For each predicted future use cycle, the prediction is based on the corresponding predicted temperature profile of the brake, the current thermal oxidation state, the predicted amount of energy absorbed by the brake during the corresponding predicted future braking event, and the corresponding predicted density parameter of the brake for the corresponding predicted future braking event.

7. The device according to claim 4 or claim 5, wherein, The processor is configured to predict future brake wear after a second plurality of predicted future use cycles, wherein the second plurality of future use cycles are a plurality of cycles after which a brake wear threshold is reached; Each predicted future uses a loop that includes multiple predicted future braking events; and For each predicted future use cycle, the prediction is based on the predicted amount of energy absorbed by the brake during the corresponding predicted future braking event and the corresponding predicted density parameter of the brake for the corresponding predicted future braking event.

8. The device according to any one of claims 1 to 5, wherein, The processor is configured to predict the future thermal oxidation state after a first plurality of predicted future use cycles, wherein the first plurality of future use cycles are a plurality of cycles after which a thermal oxidation threshold is reached; Each predicted future uses a loop that includes multiple predicted future braking events; and For each predicted future use cycle, the prediction is based on the corresponding predicted temperature profile of the brake and the current thermal oxidation state.

9. The device according to any one of the preceding claims, wherein, The processor is configured to use the thermal oxidation model to determine the thermal oxidation state after the predicted future braking event based on the high temperature interval, the initial thermal oxidation state, and the thermal oxidation rate parameter.

10. The device according to claim 9, wherein, The processor is configured to: The predicted temperature curve is compared with a set of temperature standards; and If one or more of the temperature criteria from the set of standards are met, then: Based on the comparison, high-temperature events corresponding to the predicted future braking events are identified; as well as The time interval occupied by the high-temperature event is defined as the high-temperature interval.

11. The device according to claim 10, wherein, The processor is configured to: Determine the high-temperature event value for the aforementioned high-temperature interval; and The oxidation rate parameter is determined based on the determined temperature value and the physical characteristics of the brake.

12. The device according to any one of claims 1 to 11, wherein, The processor is configured to select the thermal oxidation model based on the initial thermal oxidation state.

13. A method for determining the thermal oxidation state of a brake on an aircraft landing gear, the method comprising: The temperature profile of the input brake over time and the initial thermal oxidation state of the brake prior to the predicted future braking event; as well as The thermal oxidation state of the brake after the predicted future braking event is determined using a thermal oxidation model based on the initial thermal oxidation state and the predicted temperature curve.

14. The method of claim 13, comprising: The initial thermal oxidation state is updated using the determined thermal oxidation state after the predicted future braking event; as well as The thermal oxidation state following a predicted future braking event is determined based on the updated initial thermal oxidation state.

15. The method according to claim 13 or claim 14, comprising: The amount of brake wear caused by the predicted future braking event is determined using a brake wear model based on the amount of energy absorbed by the brake due to the predicted future braking event and the density parameter of the brake.

16. The method of claim 15, comprising: (i) Predict the future thermal oxidation state and future brake wear after the predicted future use cycle; (ii) If either the thermal oxidation threshold or the brake wear threshold is substantially reached, then determine the number of good future use cycles; otherwise, repeat (i) and (ii) for the next predicted future use cycles. in, Each predicted future uses a loop that includes multiple predicted future braking events; and For each predicted future use cycle, the prediction is based on the corresponding predicted temperature profile of the brake, the current thermal oxidation state, the predicted amount of energy absorbed by the brake during the corresponding predicted future braking event, and the corresponding predicted density parameter of the brake for the corresponding predicted future braking event.

17. An apparatus for determining the thermal oxidation level of a brake on an aircraft landing gear, the apparatus comprising: A processor configured to use a thermal oxidation evolution model of the brake to determine an updated thermal oxidation level of the brake after the braking event, based on an initial thermal oxidation level prior to the braking event and temperature data of the brake as a function of time.

Images