Device, method and computer program product for setting minimum value of shock absorber size and system for indicating shock absorber size status

Abstract

An apparatus for setting a size parameter associated with a value of a shock absorber size of a shock absorber of an aircraft landing gear is disclosed, the shock absorber size indicating an extension of the shock absorber. The apparatus includes a processor configured to: identify a corresponding range of values ​​associated with each of a plurality of operating characteristics under which the shock absorber can operate; and identify a corresponding probability distribution of values ​​for each of the operating characteristics within the identified range. The processor is further configured to perform a generation process for generating a plurality of shock absorber size values ​​by repeatedly performing the following operations: selecting a value of each of the operating characteristics as an input to a computer-implemented model for determining a value of the shock absorber size based on the corresponding probability distribution; and determining a given value of the shock absorber size using the selected value and the computer-implemented model. The processor is further configured to set the size parameter based on the generated plurality of shock absorber size values.

Description

Technical Field

[0001] The invention relates to a method for setting dimensional parameters related to a shock absorber of an aircraft landing gear. Background Art

[0002] Typically, the landing gear is inspected at an appropriate time when the aircraft is on the ground between flights to check whether the landing gear needs maintenance. Specifically, the size of the shock absorber of the landing gear can be checked, and the size of the shock absorber of the landing gear indicates the extension of the shock absorber. The size of the shock absorber indicating the extension of the shock absorber can be called the H dimension.

[0003] Check the H dimension of the landing gear and compare it to the minimum H label. If the measured H dimension of the landing gear shock absorber is greater than the minimum H dimension for the relevant condition group shown on the H label, it indicates that the landing gear does not require repair. On the other hand, if the measured H dimension is less than the minimum H dimension for the relevant condition shown on the H label, it indicates that the landing gear may require repair.

[0004] Based on the results of the landing gear inspection, engineers may ground the aircraft so that the landing gear can be repaired.

[0005] The H-tag for the landing gear may be produced and provided, for example, by the manufacturer of the landing gear. Summary of the invention

[0006] A first aspect of the present invention provides an apparatus for setting a size parameter associated with a value of a shock absorber size of a shock absorber of an aircraft landing gear, the shock absorber size indicating an extension of the shock absorber. The apparatus includes a processor configured to: identify a corresponding range of values ​​associated with each of a plurality of operating characteristics under which the shock absorber can operate; identify a corresponding probability distribution for values ​​of each of the operating characteristics in the identified range; perform a generation process for generating a plurality of values ​​of the shock absorber size by repeatedly performing the following operations: (i) selecting a value of each of the operating characteristics based on the corresponding probability distribution as an input to a computer-implemented model for determining a value of the shock absorber size; and (ii) determining a given value of the shock absorber size using the selected value and the computer-implemented model; and setting the size parameter based on the generated plurality of shock absorber size values.

[0007] Optionally, the computer implemented model includes a model of shock absorber size as a function of load on the shock absorber, the plurality of operating characteristics include an aircraft mass and a location of an aircraft center of gravity, and the generating process includes determining the shock absorber loads using the computer implemented model based on a selected aircraft mass and a selected aircraft center of gravity.

[0008] Optionally, the generating process includes selecting a value for the mass of the aircraft and a value for the centre of gravity of the aircraft based on a predetermined relationship between the mass of the aircraft and the centre of gravity of the aircraft.

[0009] Optionally, the plurality of operating characteristics includes temperature, and the generating process includes determining a first value for a shock absorber size based on the determined shock absorber load and the selected temperature.

[0010] Optionally, the plurality of operating characteristics includes an amount of fluid lost from a shock absorber, and the generating process includes determining a given value for the shock absorber size based on a selected value for the amount of fluid lost from the shock absorber and the determined first shock absorber size value.

[0011] Optionally, the plurality of operating characteristics include a gas absorption factor related to absorption of gas contained in the shock absorber into liquid contained in the shock absorber, and the generating process includes: determining an internal pressure of the shock absorber and an internal temperature of the shock absorber based on selected values ​​of the operating characteristics; determining an amount of absorption of gas entering the liquid when the liquid is fully saturated in the liquid at the determined internal pressure and the determined internal temperature; modifying the determined absorption based on the gas absorption factor to determine the gas absorption; and determining a given value for the shock absorber size based on the determined gas absorption and a first value for the determined shock absorber size.

[0012] Optionally, the processor is configured to: perform a first iteration of the generation process based on a first determined shock absorber load value, including determining a first value for gas absorption; and perform a second iteration of the generation process based on a second determined shock absorber load value and the first value for gas absorption, the second determined shock absorber load value being greater than the first determined shock absorber load value.

[0013] Optionally, the processor is configured to compare the given value of the shock absorber size generated in the second iteration with a predetermined value indicative of a limit of the shock absorber range of motion.

[0014] Optionally, the processor is configured to generate a probability distribution of shock absorber sizes based on the generated plurality of shock absorber size values, and to set the size parameter based on the generated probability distribution.

[0015] Optionally, the processor is configured to determine a probability that a value of a shock absorber dimension is below a given value and to set said dimension parameter based on the comparison.

[0016] Optionally, the size parameter comprises a minimum value for the size of the shock absorber.

[0017] Optionally, the processor is configured to set a plurality of minimum values ​​for respective sets of values ​​of at least some of the operating characteristics.

[0018] A second aspect of the present invention provides a system for indicating a state of a shock absorber fitted to an aircraft, the system comprising an apparatus according to the first aspect, and the system further comprising: a computer-readable storage medium having stored thereon a plurality of minimum values ​​of shock absorber dimensions for the corresponding plurality of sets of values; a shock absorber dimension measuring device for obtaining a current value of the shock absorber dimension; one or more instruments for measuring the current values ​​of at least some of the operating characteristics; and an indication device for providing an indication that the current measured value of the shock absorber dimension is less than a minimum value for a first set of values ​​in the plurality of sets of values. The system is configured to: identify a first set of values ​​in the plurality of sets of values ​​based on the current measured values ​​of at least some of the operating characteristics; and determine whether the measured shock absorber dimension is less than the minimum value of the identified first set of values, and if the measured shock absorber dimension is less than the minimum value of the identified first set of values, cause the indication device to provide an indication.

[0019] Optionally, the damper dimension measuring device is one of a potentiometer, an electromechanical device, a laser device, and an ultrasonic device.

[0020] Optionally, the processor is configured to update one or more of the probability distributions using current measurements of the set of the plurality of operating characteristics.

[0021] A third aspect of the present invention provides a method for setting a size parameter associated with a value of a shock absorber size of a shock absorber of an aircraft landing gear, the shock absorber size indicating the extension of the shock absorber. The method comprises: identifying a corresponding range of values ​​associated with each of a plurality of operating characteristics under which the shock absorber can operate; identifying a corresponding probability distribution for the value of each of the operating characteristics within the determined range; performing a generation process for generating a plurality of shock absorber size values ​​by repeatedly performing the following operations: (i) selecting a value of each of the operating characteristics based on the corresponding probability distribution as an input to a computer-implemented model for determining a value of the shock absorber size; and (ii) determining a given value of the shock absorber size using the selected value and the computer-implemented model; and setting the size parameter based on the generated plurality of shock absorber size values.

[0022] Optionally, the computer implemented model includes a model of shock absorber size as a function of load on the shock absorber, the plurality of operating characteristics include an aircraft mass and a location of an aircraft center of gravity, and the generating process includes determining the shock absorber loads using the computer implemented model based on a selected aircraft mass and a selected aircraft center of gravity.

[0023] Optionally, the generating process includes selecting a value for the mass of the aircraft and a value for the centre of gravity of the aircraft based on a predetermined relationship between the mass of the aircraft and the centre of gravity of the aircraft.

[0024] Optionally, the plurality of operating characteristics includes temperature, and the generating process includes determining a first value for a shock absorber size based on the determined shock absorber load and the selected temperature.

[0025] Optionally, the plurality of operating characteristics includes an amount of fluid lost from a shock absorber, and the generating process includes determining a given value for the shock absorber size based on a selected value for the amount of fluid lost from the shock absorber and the determined first shock absorber size value.

[0026] Optionally, the plurality of operating characteristics include a gas absorption factor related to absorption of gas contained in the shock absorber into liquid contained in the shock absorber, and the generating process includes: determining an internal pressure of the shock absorber and an internal temperature of the shock absorber based on selected values ​​of the operating characteristics; determining an amount of absorption of gas entering the liquid when the liquid is fully saturated in the liquid at the determined internal pressure and the determined internal temperature; modifying the determined absorption based on the gas absorption factor to determine the gas absorption; and determining a given value for the shock absorber size based on the determined gas absorption and a first value for the determined shock absorber size.

[0027] Optionally, the method includes performing a first iteration of the generation process based on a first determined shock absorber load value, including determining a first value for gas absorption; and performing a second iteration of the generation process based on a second determined shock absorber load value and the first value for gas absorption, the second determined shock absorber load value being greater than the first determined shock absorber load value.

[0028] Optionally, the method comprises comparing a given value of the shock absorber size generated in the second iteration with a predetermined value indicative of a limit of the range of motion of the shock absorber.

[0029] Optionally, the method comprises generating a probability distribution of shock absorber sizes based on the generated plurality of shock absorber size values, and setting the size parameter based on the generated probability distribution.

[0030] Optionally, the method comprises determining a probability that a value of a shock absorber dimension is less than a given value, and setting said dimension parameter based on the comparison.

[0031] Optionally, the size parameter comprises a minimum value for the shock absorber size.

[0032] Optionally, the method comprises setting a plurality of minimum values ​​for respective sets of values ​​of at least some of the operating characteristics.

[0033] Optionally, the method includes measuring current values ​​for at least some of the operating characteristics of the shock absorbers fitted to the aircraft; identifying a first set of values ​​from the plurality of sets of values ​​based on the identified current values; performing a measurement of a size of the shock absorber on the aircraft; and determining whether the measured size of the shock absorber is less than a minimum value of the identified first set of values, and if the measured size of the shock absorber is less than the identified minimum value of the first set of values, providing an indication that the measured size of the shock absorber is less than the identified minimum value of the first set of values.

[0034] Optionally, the method includes performing the measurement of the damper dimensions using at least one of a potentiometer, an electromechanical device, a laser device, and an ultrasonic device.

[0035] Optionally, the method comprises updating one or more of said probability distributions using a current measurement of the operating characteristic.

[0036] A fourth aspect of the present invention provides a computer program product, which, when executed by a processor, causes the processor to perform the method according to the first aspect.

[0037] A fifth aspect of the present invention provides a device for setting a minimum value of a shock absorber size of a shock absorber of an aircraft landing gear, the shock absorber size indicating the extension of the shock absorber. The device includes a processor configured to: determine a corresponding range of values ​​associated with each of a plurality of operating characteristics, wherein the shock absorber can operate under the conditions of the plurality of operating characteristics; determine a corresponding probability distribution of values ​​for each of the plurality of operating characteristics, wherein the shock absorber can operate under the conditions of the plurality of operating characteristics; perform a Monte Carlo simulation process by iteratively performing the following operations to generate a plurality of values ​​of the shock absorber size: (i) selecting a value of each of the operating characteristics based on the corresponding probability distribution as an input to a computer-implemented model for determining a value of the shock absorber size; and (ii) determining a given value of the shock absorber size using the selected value and the computer-implemented model; and setting a minimum value based on the generated plurality of shock absorber size values. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which

[0039] In the figure:

[0040] Figure 1a A schematic diagram of an aircraft is shown;

[0041] Figure 1b Shows Figure 1a A schematic diagram of the landing gear of an aircraft;

[0042] Figure 2An example of a label indicating a size parameter of a shock absorber size is shown;

[0043] Figure 3 is a flow chart of a method for setting dimensional parameters for shock absorber size;

[0044] Figure 4 showing probability distributions of operational characteristics associated with the aircraft;

[0045] Figure 5 is a flow chart illustrating a method of determining the size of a shock absorber;

[0046] Figure 6 shows a graph indicating the relationship between the travel and load of the shock absorber;

[0047] Figures 7a to 7c is a schematic diagram showing different extensions of the shock absorber; and

[0048] Figure 8 An example of a computing device is shown. DETAILED DESCRIPTION

[0049] Figure 1a 1 is a simplified schematic diagram of an aircraft 100. Aircraft 100 includes a plurality of landing gears 101. Landing gears 101 may include main landing gear and nose landing gear that may be extended during takeoff and landing. Aircraft 100 also includes a computing system 103 and instruments 105, such as measuring instruments for measuring environmental or other conditions such as temperature. Computing system 103 may, for example, include one or more processors and one or more computer-readable storage media. Aircraft 100 may also include an indication device 107 for providing various indications and operating characteristics related to aircraft 100.

[0050] Figure 1b 1 is a simplified schematic diagram of a nose landing gear 101 of an aircraft in a configuration when the aircraft is stationary on the ground. Although the following description is about the nose landing gear 101, the present invention is equally applicable to other types of landing gear, such as main landing gear, for example. The landing gear can include a main fitting 102 that attaches the landing gear 101 to the fuselage of the aircraft 100. The landing gear 101 includes a shock absorber 102. The landing gear 101 can be configured to be retracted into the fuselage of the aircraft when the landing gear 101 does not need to be extended. The shock absorber 102 includes a main fitting 104. A connecting structure 110 connects the shock absorber 102 to wheels 112a, 112b that contact the ground when the aircraft is on the ground.

[0051] exist Figure 1bIn the example of , the shock absorber 102 includes a chamber 106, which can contain a liquid 106a and a gas 106b that are in fluid communication with each other. The liquid 106a contained in the chamber 106 can be, for example, oil, and the gas 106b contained in the chamber 106 can be, for example, an inert gas, such as nitrogen (N2). Any liquid and gas suitable for use in a shock absorber of an aircraft landing gear can be used. The shock absorber 102 also includes a sliding member 108, which can also be referred to as a piston 108. The piston 108 translates into the main assembly 104 as shown by arrow 114 against the pressure of the gas 106b and liquid 106a in the chamber 106.

[0052] exist Figure 1b In the example of , a portion of the piston 108 having a dimension indicated by arrow 116 extends downward from the main fitting 104 to the connecting structure 110. The shock absorber 102 may include a shock absorber dimension measuring device 118 for performing measurements of the shock absorber dimension 116. This dimension - referred to herein as the "H dimension" - indicates the extension of the shock absorber as it changes depending on the degree of extension. The H dimension can indicate the amount of remaining travel of the shock absorber, for example, the length of the piston 108 that can be slid into the main fitting 104. For example, depending on the manufacturer, different definitions of the H dimension may be used; in other words, the points between which the H dimension will be measured may be changed. For example, a manufacturer of the landing gear may provide markings on certain components of the shock absorber, between which the H dimension is measured.

[0053] Figure 2 An example of a label 200 indicating a dimension parameter related to the value of the shock absorber dimension is shown. The dimension parameter indicated in the label 200 is compared with the measured shock absorber 102 parameters to determine whether the landing gear 101 requires maintenance. Figure 2In the example of FIG. 1 , the dimension parameter is the minimum value of the shock absorber dimension. Specifically, in this example, the dimension parameter is the minimum shock absorber H dimension 116 value. Therefore, the label 200 is an example of a minimum H label. The illustrated minimum H label 200 is a table in which each column represents a range of aircraft masses and each row represents a range of ambient temperatures. Aircraft masses and ambient temperatures are examples of operating characteristics under which the shock absorber 101 can operate. For each combination of an aircraft mass range and an ambient temperature range, the minimum H label 200 indicates the minimum H dimension value in units of length. The H dimension 116 of the landing gear 101 can be measured during an inspection of the landing gear 101 and compared with the relevant value provided in the minimum H label 200. For example, for a case where the ambient temperature is greater than 40° C. and the aircraft weight is less than 175 tons, the minimum H dimension measurement value is indicated as 102 mm in the minimum H label 200. If the measured H dimension 116 value for these operating characteristics is greater than 102 mm, it can be determined that the landing gear 101 does not require maintenance. On the other hand, if the measured H dimension 116 for these operating characteristics is less than 102 mm, then it may be determined that the landing gear 101 is in need of repair.

[0054] If it is determined that the landing gear 101 requires maintenance, the aircraft 100 to which the landing gear 101 belongs may be "grounded" until maintenance of the landing gear 101 can be performed. Here, the term "grounded" means that the aircraft in question is not allowed to fly, for example, despite carrying passengers. In some examples, the aircraft 100 may be sent to a suitable location for maintenance of the landing gear 101 of the aircraft 100.

[0055] To generate the minimum H label, such as Figure 2 , the manufacturer of the landing gear 101 conventionally performs a deterministic calculation using values ​​for various operating characteristics of the landing gear 101 that do not require maintenance, and this will produce a minimum value for the H dimension. Thus, the minimum H dimension for which the landing gear 101 does not require maintenance can be calculated for certain operating characteristics, such as various aircraft mass ranges and ambient temperature ranges, and provides, for example, Figure 2 The minimum H tag in .

[0056] Figure 3 The steps of an iterative method 300 for setting a dimension parameter associated with a minimum value of a shock absorber dimension of a shock absorber of an aircraft landing gear according to an embodiment of the present invention are summarized, the dimension being indicative of an extension of the shock absorber 102. For example, the method 300 involves setting a minimum value for an H dimension of the shock absorber 102 such that a measured H dimension value 116 below the set minimum value indicates that the landing gear 101 requires maintenance, while a measured H dimension value 116 above the minimum value set using the method 300 indicates that the landing gear 101 does not require maintenance. Thus, the method 300 may be used to generate, for example, Figure 2 The minimal H tag is shown in .

[0057] The method 300 includes executing a generation process for generating a plurality of values ​​for a shock absorber dimension, such as the H dimension 116 , and setting a minimum value for the H dimension based on the generated plurality of H dimension values.

[0058] Step 302 of method 300 involves identifying a respective range of values ​​associated with each of a plurality of operating characteristics at which the shock absorber 102 may operate. For example, the plurality of operating characteristics may include the mass of the aircraft, the location of the center of gravity of the aircraft, the ambient temperature, the amount of oil lost from the shock absorber 102, and / or a gas absorption factor associated with absorption of the gas 106b contained in the shock absorber 102 into the oil 106a contained in the shock absorber 102. It will be appreciated from the above description that the oil 106a and the gas 106b contained in the shock absorber 102 are contained in the chamber 106 in the example of the shock absorber 102 shown in FIG.

[0059] Some operating characteristics, such as, for example, the amount of oil lost from shock absorber 102 and the gas absorption factor of gas 106b in chamber 106, are indicative of the state of landing gear 101. Other operating characteristics, such as, for example, the mass of aircraft 100, may be operating characteristics related to the state in which landing gear 101 is expected to operate.

[0060] For example, corresponding ranges of values ​​for operating characteristics related to conditions under which landing gear 101 is expected to operate may be based on data collected regarding conditions under which the aircraft is used. For example, a range of values ​​for aircraft mass may be identified as a range of aircraft masses that takes into account the number of passengers, the amount of luggage, the amount of fuel, etc., and under which aircraft 100 is expected to operate. The corresponding ranges of values ​​are such that each range of values ​​corresponds to an expected range of values.

[0061] The corresponding range of values ​​for the operating characteristic indicating the state of the landing gear 101 may be a range in which the shock absorber 102 is expected to operate normally. In other words, each corresponding range of values ​​indicating the state of the landing gear 101 may be such that the landing gear 101 is expected to not require maintenance. For example, a range of values ​​for the oil loss from the chamber 106 may be such that the landing gear 101 may not require maintenance. For example, the corresponding range of values ​​for the operating characteristic indicating the state of the landing gear 101 may be identified as a range centered around a nominal value of the operating characteristic. For example, a range of values ​​for the oil loss may be identified based on an appropriate range of the amount of oil 106a in the shock absorber 102 within which the shock absorber 102 is expected to operate normally, and the range of values ​​for the oil loss is centered around the rated / recommended amount of oil 106a in the shock absorber 102. For example, for an operating characteristic such as a gas absorption factor, a range of values ​​may be identified based on the amount of time that the landing gear 101 will be under a specific load corresponding to a specific gas pressure in the chamber 106. Such an amount of time may be related to gas absorption factors, because the gas 106b in the chamber 106 may be expected to be absorbed into the oil 106a in the chamber 106 at a certain rate under the gas pressure conditions in the chamber 106. To set the minimum H dimension 116, a range may be selected around worst-case conditions, such as maximum oil loss, maximum gas absorption, minimum temperature, and most adverse mass and center of gravity conditions, in order to focus on conditions that are most likely to produce a low H dimension 116.

[0062] At step 304 of method 300, a respective probability distribution for values ​​of each of the operating characteristics within the identified range is identified. For example, probability distributions for aircraft mass, location of the aircraft center of gravity, ambient temperature, oil loss from shock absorbers, and / or gas absorption factors may be identified.

[0063] Figure 4 An example of a probability distribution that can be identified is shown in . Figure 4 Graph 400 shows the probability density as a function of aircraft mass.

[0064] At step 306 of method 300, a value for each of the operating characteristics is selected based on the corresponding probability distribution. The value for each of the operating characteristics is selected as an input to a computer-implemented model for determining a value of the H dimension of shock absorber 102. The computer-implemented model may be, for example, a mathematical model. More details of the computer-implemented model for determining H dimension 116 are described in detail below.

[0065] In step 308 , a given value for the shock absorber H dimension 116 is determined using the selected value and the computer implemented model.

[0066] In step 310, it is checked whether the desired number of values ​​of the damper H dimension has been generated. In other words, in step 310, it is checked whether a specified number of iterations of steps 306 to 308 have been performed. If the specified number of iterations has not been performed, and therefore the desired number of values ​​of the damper H dimension 116 has not been generated, the process proceeds to step 306 and steps 306 to 310 are repeated. Thus, the generation process generates a desired plurality of values ​​of the damper H dimension 116. Thus, the generation process for generating a plurality of values ​​of the damper H dimension is performed by repeatedly performing steps 306 to 308 of the method 300. The method 300 may be considered to include a Monte Carlo (MC) simulation.

[0067] The specified number of iterations may be specified by a user of the method 300, for example, when the user initiates the method. For example, the number of iterations may be selected based on the amount of computing resources available to perform the method.

[0068] In step 314, a minimum value of the damper H dimension 116 is set based on the generated plurality of damper H dimension 116 values. For example, for a given aircraft mass and ambient temperature range, different minimum H dimension 116 values ​​may be selected to generate a minimum H tag, such as Figure 2 100. In one example, for each combination of aircraft mass and ambient temperature shown in minimum H-tag 200, the minimum H dimension value generated during the generation process for that range of combinations of aircraft mass and ambient temperature can be set as the minimum value of H dimension 116. In one example, the range of values ​​identified for the operating characteristic indicative of the condition of landing gear 101 can be such that landing gear 101 is not expected to require maintenance. Thus, multiple minimum values ​​of damper H dimension 116 can be set for corresponding multiple sets of values ​​for at least some of the operating characteristics.

[0069] The plurality of operating characteristics for which corresponding ranges of values ​​are identified in step 302 of method 300 may include some or all of the operating characteristics considered in the computer-implemented model. The computer-implemented model may consider at least the following operating characteristics: vehicle mass, location of the vehicle center of gravity, ambient temperature, amount of oil lost from the shock absorber 102, and a gas absorption factor related to absorption of gas 106b contained in the shock absorber 102 into oil 106a contained in the shock absorber 102. In some examples, in step 302, ranges of values ​​may be identified for all of the operating characteristics considered in the computer-implemented model. However, in other examples, the values ​​of some of the operating characteristics may be fixed to specific values ​​as inputs in the computer-implemented method. For example, the amount of oil loss and the gas absorption rate may be fixed.

[0070] Now refer to Figure 5 The computer implemented model mentioned above is described in further detail and as an example, wherein respective ranges of values ​​for all operating characteristics considered in the computer implemented model are identified in step 302. In this example, the computer implemented model considers the mass of the aircraft, the location of the center of gravity of the aircraft, the ambient temperature, the amount of oil loss from the shock absorber 102, and a gas absorption factor related to the absorption of the gas 106b contained in the shock absorber 102 in the oil 106a contained in the shock absorber 102.

[0071] Figure 5 is a flow chart of method 500, which shows steps that can be performed as part of steps 306 to 308 of method 300. Step 502 of method 500 is a specific example of step 306 of method 300. In step 502, the values ​​of some of the operating characteristics can be selected based on specific criteria. For example, the value of the aircraft mass and the value of the aircraft center of gravity can be selected based on a predetermined relationship between the aircraft mass and the position of the aircraft center of gravity. The predetermined relationship can limit the combination of the aircraft mass and the position of the aircraft center of gravity, so that the combination of the actual aircraft mass and the position of the aircraft center of gravity is selected. For example, the combination of the actual aircraft mass and the position of the aircraft center of gravity can be a combination that, for the selected aircraft mass, the position of the aircraft center of gravity will not cause the aircraft 100 to be unstable when on the ground. For example, according to the predetermined relationship, the following combination will be excluded: for the selected aircraft mass, the position of the aircraft center of gravity is toward the tail of the aircraft 100, which will cause the risk of the aircraft 100 tilting backwards. In one example, the predetermined relationship may also limit the combinations of aircraft mass values ​​and aircraft center of gravity values ​​to those within a “take-off envelope.” The take-off envelope may define the combinations of aircraft mass values ​​and aircraft center of gravity values ​​expected prior to take-off.

[0072] In step 504 of method 500, the values ​​of the selected operating characteristics are input into a computer-implemented model for determining a value for the shock absorber H dimension 116. The computer-implemented model may, for example, include determining shock absorber loads and determining the shock absorber H dimension 116 based on the determined loads. The computer-implemented model may also account for oil loss and gas absorption factors from the shock absorber.

[0073] During the generation process, the computer-implemented model is used to determine the loads on the shock absorber 102 based on the selected values ​​of the aircraft mass and the aircraft center of gravity position in step 506. More specifically, in step 506, a static balance calculation using the selected aircraft mass and the selected aircraft center of gravity is performed to determine the ground reaction loads on the landing gear 101. The ground reaction loads may be defined as the loads on the landing gear 101 due to the reaction forces from the ground in response to the weight of the aircraft 100 supported by the landing gear 101. The ground reaction forces are resolved into the axis of the shock absorber 102 based on the front angle 119 of the shock absorber 102 shown in FIG. 1 .

[0074] The computer implemented model includes a model of the variation of the shock absorber H dimension 116 with the load on the shock absorber 102 (hereinafter referred to as the spring force curve model). In step 508, a set of spring force curves associated with the shock absorber 102 are selected from the spring force curve model. Figure 6 An example of a set of spring force curves 600 is shown in FIG. Figure 6 The spring force curve 600 shows the relationship between the shock absorber load "SA load" in deca Newtons (daN) and the shock absorber travel "SAT" in millimeters for different temperatures. Figure 6 In the example of FIG. 6 , elastic force curve 602 shows the relationship between load and SAT when the temperature is 30° C., elastic force curve 604 shows the relationship between load and SAT when the temperature is 0° C., and elastic force curve 606 shows the relationship between load and SAT when the temperature is −30° C. The elastic force curve group for each temperature may include a ratio of Figure 6 The elasticity curve shown in the figure is more or less elasticity curve.

[0075] Refer again Figure 5 In step 510, a particular spring force curve is selected from the set of selected spring force curves based on the ambient temperature selected in step 306. A first value for the shock absorber H dimension 116 is determined using the selected spring force curve and based on the determined load on the shock absorber. Thus, in step 406, a first value for the shock absorber H dimension 116 is determined based on the determined shock absorber load and the selected temperature.

[0076] In step 512 , the first value of the shock absorber H dimension 116 is adjusted based on the selected value of the amount of oil loss from the shock absorber.

[0077] In step 514, the first value of the shock absorber H dimension 116 is also adjusted based on the gas absorption amount. Figures 7a to 7c Step 514 is described in more detail. Figure 7aThe components of the shock absorber 102 are shown when the shock absorber 102 is fully extended - in other words, when the piston 108 is at its maximum extension from the self-fitting member 104 (not shown). Figures 7a to 7c Oil 106a and gas 106b in chamber 106 are shown.

[0078] exist Figure 7a In, V a , P a 、T a are the volume, inflation pressure and inflation temperature of the gas 106b when the shock absorber 102 is fully extended. The relationship between the gas pressure in the shock absorber of the aircraft landing gear and the amount of gas 106b absorbed into the oil 106a is determined using an experimental relationship obtained from the experiment. a The amount of gas 106b that saturates the oil 106a is X a ——The quantity X a The unit may be, for example, the number of moles of gas 106b absorbed per liter of oil 106a, and the number of moles may be calculated using the following equation 1:

[0079] n 油a =X a × Volume of Oil 602 (1)

[0080] In Equation 1 above, n 油a For the pressure P a and temperature T a In this example, step 514 includes determining an internal pressure of the shock absorber 102 and an internal temperature of the shock absorber 102 based on the selected value of the operating characteristic. For example, the internal pressure and temperature can be determined based on the selected ambient temperature and the determined shock absorber load. Figure 7b FIG. 1 shows the extension of the shock absorber 102 when the determined shock absorber load is applied and taking into account the selected amount of oil loss. The internal volume of the gas 106b in the shock absorber 102 when the determined shock absorber load is applied can be based on the shock absorber from Figure 7a The full extension of Figure 7b In this example, due to the determined damper load, it is determined that the gas 106b has a determined volume V b , the determined internal pressure P b And the determined internal temperature T b , pressure P b depends on the load. However, due to the pressure P a To P b As the pressure increases, the number of moles of gas 106b absorbed into the oil may increase. Figure 7b A situation is shown in which the increase in absorption of the gas 106b into the oil 106a is not taken into account.

[0081] Step 514 also includes determining the amount of gas 106b absorbed into oil 106a when gas 106b is fully saturated in oil 106a. Then, using the experimental relationship obtained by applicant mentioned above, it is determined that at pressure P b and temperature T b In the case of b Then, the pressure P is modified according to the selected gas absorption factor. b and temperature T b The absorption saturation amount in the case of , to determine the gas absorption amount using the following equation 2:

[0082] n 油c = selected gas absorption factor × X b × Volume of Oil 602 (2)

[0083] In Equation 2 above, n 油c is the determined gas absorption. Then, the following equation 3 is used to determine the gas absorption amount (n 油c -n 油a ) changes in the shock absorber H dimension 116:

[0084]

[0085] In the above Equation 3, A represents the surface area of ​​the piston 108 in contact with the oil 106a, and R represents an ideal gas constant. Figure 7c The change ΔH in the shock absorber H dimension 116 is shown in FIG. The change ΔH in the shock absorber H dimension 116 is used to adjust the H dimension 116 calculated in the step before step 514. Therefore, in this example, in step 516, based on the determined gas absorption amount n 油c The set value of the shock absorber H dimension 116 is determined by combining the adjusted shock absorber H dimension 116 first value from step 512 .

[0086] In some examples, the adjustment value determined in step 512 taking into account the oil loss is determined as the given amount of the shock absorber H dimension 116 in step 516, and step 514 is eliminated. Thus, in some examples, the given value of the shock absorber H dimension 116 is determined based on the selected value of the amount of oil loss from the shock absorber 102 and the determined first value of the shock absorber H dimension 116. In other examples, the method 500 proceeds to step 514 before determining the given value of the shock absorber H dimension 116 in step 516.

[0087] In some examples, as shown above, Figure 5 7 , the adjustment value from step 408 is further adjusted based on the gas absorption amount to determine the given value of the shock absorber H size in step 516. In these examples, the given value of the shock absorber H size 116 is determined based on the gas absorption amount, the selected oil loss amount, and the determined first value of the shock absorber H size 116. However, in some examples, step 512 is removed, and the first value of the shock absorber H size 116 is adjusted based on the gas absorption amount. More specifically, in these examples, the given value of the shock absorber H size 116 is determined based on the gas absorption amount and the determined first value of the shock absorber H size 116.

[0088] Refer again Figure 3 It will be appreciated that step 312 of setting the minimum value of the damper H dimension 116 of method 300 may be performed after performing method 500. As described above, in step 312, a plurality of minimum values ​​of the damper H dimension 116 for respective sets of values ​​of at least some of the operating characteristics may be set. In one example, when the range of values ​​indicative of the state of the landing gear 101 identified for the operating characteristic may be such that it is anticipated that no maintenance of the landing gear 101 is required, for each combination of aircraft mass and ambient temperature shown in the minimum H label 200, the minimum H dimension value generated during the generation process for that combination of aircraft mass and ambient temperature range may be set as the minimum value of the H dimension 116.

[0089] In some examples, based on the multiple values ​​of the shock absorber H dimension 116 generated in the above-described generation process, a probability distribution of the shock absorber H dimension 116 may be generated. A minimum value of the shock absorber H dimension 116 may be set based on the generated probability distribution of the H dimension. For example, the probability distribution of the H dimension may indicate the probabilities of various H dimension values ​​occurring when the shock absorber 102 is expected to operate normally, in other words, the corresponding range of values ​​of the operating characteristic used to generate the probability distribution of the H dimension makes the shock absorber 102 expected to operate normally. The minimum H dimension value may be set based on a probability threshold and using the generated probability distribution of the H dimension. For example, the minimum H dimension value may be set to be greater than the minimum H dimension value having a probability of occurrence less than the probability threshold when the shock absorber 102 is operating normally.

[0090] In other examples, other criteria may be used to set the minimum value of the damper H dimension 116. In one example, a "rolling over a bump" criterion may be used. In this example, the above reference is performed based on a 20% increase in the load on the damper, or other suitable values ​​that simulate the damper load when the wheels 112a, 112b roll over a bump or other topological feature. Figure 3 and Figure 5The MC simulation described herein is described. A modified damper H dimension value is then generated, and a determination is made as to whether the modified damper H dimension value represents "bottoming" of the damper 102 (i.e., the damper 102 has exhausted its range of travel). The determination may include comparing the determined modified H dimension value to a "bottoming" value, i.e., a predetermined value indicating the limit of the range of motion of the damper 102 (i.e., the range of travel of the damper 102). The bottoming value depends on factors including the geometry of the damper 102 and the amount of fluid in the damper 102.

[0091] In this case, in addition to the above reference Figure 3 and Figure 5 In addition to the described process, an MC simulation may also be performed. That is, for each iteration of steps 306 to 308 performed using a given damper load value, a corresponding iteration using an increased load (e.g., an increase of 20%) is performed. However, in the latter case, it should be noted that the gas absorption amount used in the computer-implemented model is set to the same value as in the previous case, rather than being recalculated using the increased load value. This is in view of the fact that the increased load as a result of the simulation is instantaneous (due to a sudden impact such as the aircraft 100 sliding over a bump), and therefore the amount of gas absorbed due to any increase in pressure during the load increase is not expected to be significant.

[0092] Thus, the probability that a properly functioning shock absorber 102 will have an H dimension value below the given H dimension may be determined first (hereinafter referred to as the "first probability"), and secondly, the probability that a properly functioning shock absorber 102 with a given H value will "bottom out" - i.e., use up its range of travel - may be determined (the "second probability"). In general, the higher the given H dimension value, the greater the first probability, and the less the second probability. Since low values ​​for the first probability (in order to avoid unnecessarily grounding the aircraft) and low values ​​for the second probability (in order to avoid bottoming out situations) are generally desirable, a value may be selected to be set as the minimum H value that balances these two conflicting requirements. For example, a value may be set that produces a 10 for both the first probability and the second probability. -6 or lower value.

[0093] For example, the probability distribution of the H dimension may be used to evaluate the value specified in the minimum H label provided by the manufacturer. For example, the probability that the shock absorber H dimension 116 has a value below a given minimum H dimension from the manufacturer's minimum H label may be determined, and the minimum value of the shock absorber H dimension 116 may be set based on the determination of the probability.

[0094] As described above, comparison of the probability distribution of H dimensions generated using the above method with the minimum H tags provided by the manufacturer and modification of those minimum H tags by setting new minimum H dimension values ​​may be advantageous in situations where the manufacturer minimum H tag values ​​are too conservative. For example, in some cases, the manufacturer minimum H tag may indicate a certain minimum value, and it may be the case that the landing gear 101 does not actually require maintenance when the H dimension 116 is below that particular minimum value. In such an example, the aircraft 100 may be grounded when it is not actually necessary to ground the aircraft 100. Therefore, modifying the minimum H tag as described above may avoid unnecessary grounding of the aircraft 100.

[0095] In some examples, where a probability distribution of H dimensions is generated for operational characteristics that are not expected to require maintenance of the landing gear, if the non-zero probability of the shock absorber H dimension 116 being less than a particular minimum value on the manufacturer's minimum H label, an updated minimum H label may be generated, where the minimum value in question is reduced according to an acceptable probability tolerance.

[0096] As described above, corresponding minimum values ​​of H dimension 116 may be set for corresponding sets of values ​​for at least some of the operating characteristics, such as, for example, those sets of values ​​shown in minimum H tag 200. In other words, minimum H tags such as minimum H tag 200 may be generated using the above method.

[0097] For example, one can use Figure 8 The computing device 800 shown in the figure can be used to perform the above-mentioned methods and MC simulations. The computing device 800 can include a processor 802 and a computer-readable storage medium 804. The processor 802 can be configured to execute instructions stored on the storage medium 804. The storage medium 804 can store instructions for performing all or part of any of the above-mentioned methods and MC simulations. In some examples, the computing device 800 for performing the above-mentioned methods can be included in the computing system 103 of the aircraft 100. In other examples, the computing device 800 can be an external device.

[0098] All or part of the instructions for performing the above methods and simulations can be generated and / or executed using any suitable software or software combination. In one example, "MATLAB" can be used to generate all or part of the instructions for a processor such as processor 802 to perform any of the above methods and simulations, and / or a processor such as processor 802 can be used to perform all or part of the above methods and simulations. In other examples, other software packages can be used. For example, any suitable programming language, development environment, and software package, etc. can be used. Other examples of programming languages ​​include PYTHON, C++, C, JAVASCRIPT, and FORTRAN, etc.

[0099] For example, an indication of a dimensional parameter related to the size of the shock absorber, such as the minimum H label 200, may be provided in the form of a hard copy label, such as a sticker, etc. The label indicating the dimensional parameter may also be provided in electronic form. In some examples, a minimum H label, such as the minimum H label 200, may be provided in electronic form and stored in a computer-readable storage medium. In some examples, the electronic minimum H label may be stored in a computer-readable storage medium maintained in the aircraft. For example, the electronic minimum H label may be stored in a computer-readable storage medium included in the computing system 103 of the aircraft 100.

[0100] In some examples, current values ​​of operating characteristics of the shock absorber 102 shown in the generated minimum H tag may be measured, wherein the shock absorber 102 is mounted to the landing gear 101 of the aircraft 100. For example, using the instrument 105 included in the aircraft 100, the current aircraft mass and the current ambient temperature value may be measured. In other examples, one or more current measured values ​​of the operating characteristics may be transmitted to the computing system 103 of the aircraft 100. For example, a user may input the one or more current measured values ​​of the operating characteristics into the computing system 103 using an input device such as a keyboard. Based on these measurements, a first set of values ​​in a plurality of sets of values ​​may be identified based on the identified current values. For example, based on the measurements from the instrument 105 on the aircraft 100, it may be determined that the aircraft mass is less than 175 tons and the ambient temperature is greater than 40° C. In response to these determinations, a first set of values ​​associated with a generated minimum H tag, such as the minimum H tag 200, may be identified as “<175” aircraft mass in tons and “40+” ambient temperature in ° C. For example, the comparison may be performed using computing system 103 of aircraft 100 and using the minimum H-tag generated in electronic form.

[0101] In these examples, the aircraft 100 may include an instrument, such as, for example, a shock absorber dimension measuring device 118 disposed on the shock absorber 102, for performing a measurement of the shock absorber H dimension 116. Examples of these measuring devices include potentiometers, electromechanical devices, laser devices, and ultrasonic devices, among others. The measured value of the H dimension 116 may then be compared to a minimum H tag value, for example, based on an electronic minimum H tag, for the identified first set of values. For example, similar to the minimum H tag 200, the generated minimum H tag for the first set of values ​​may indicate a minimum H dimension of 102 mm. If the measured H dimension value is less than 102 mm, an indication that the measured value is less than the minimum value for the identified first set of values ​​may be provided. For example, the indication may be provided by an indication device 107 included in the aircraft 100. The indication may be provided, for example, using any suitable means, for example, using a warning light on a device for controlling the aircraft 100, a warning sound, a visual indication on a display screen, and the like.

[0102] Thus, the devices included in the aircraft 100 and the computing device 800 may, for example, form part of a system for indicating the state of a shock absorber fitted to the aircraft.

[0103] In some examples, the current value of the measured operating characteristic may be used to update one or more of the probability distributions mentioned with respect to method 300. This allows for the generation of a minimum H-tag that is more appropriate for a particular aircraft or airline.

[0104] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A device for setting a minimum value of a damper size of a damper of an aircraft landing gear, the damper size indicating an extension of the damper, the device comprising: A processor, the processor being configured to: identifying a respective range of values ​​associated with each of a plurality of operating characteristics at which the shock absorber is operable; identifying, for each of the operating characteristics, a corresponding probability distribution for values ​​within the identified range; The generation process for generating multiple damper size values ​​is performed by repeatedly performing the following operations: (i) selecting, based on the corresponding probability distribution, a value for each of the operating characteristics as an input to a computer-implemented model for determining a value for the shock absorber size; and (ii) determining a given value for the shock absorber size using the selected value and the computer implemented model; and The minimum value is set based on the generated plurality of damper size values.

2. The device according to claim 1, wherein: The computer implemented model includes a model of the shock absorber size as a function of load on the shock absorber, the plurality of operating characteristics include an aircraft mass and a location of an aircraft center of gravity, and the generating process includes determining the shock absorber loads using the computer implemented model based on a selected aircraft mass and a selected aircraft center of gravity.

3. The device according to claim 2, wherein: The generating process includes selecting a value for the vehicle mass and a value for the vehicle center of gravity based on a predetermined relationship between the vehicle mass and the vehicle center of gravity.

4. The device according to claim 2 or claim 3, wherein: The plurality of operating characteristics includes temperature, and the generating process includes determining a first value for the shock absorber size based on the determined shock absorber load and the selected temperature.

5. The device according to claim 4, wherein: The plurality of operating characteristics includes an amount of fluid lost from the shock absorber, and the generating process includes determining a given value for the shock absorber size based on a selected value for the amount of fluid lost from the shock absorber and the determined first shock absorber size value.

6. The device according to claim 4, wherein: The plurality of operating characteristics includes a gas absorption factor related to absorption of gas contained in the shock absorber into liquid contained in the shock absorber, and the generating process includes: determining an internal pressure of the shock absorber and an internal temperature of the shock absorber based on the selected value of the operating characteristic; determining an absorption amount of the gas into the liquid when the liquid is fully saturated in the liquid at the determined internal pressure and the determined internal temperature; modifying the determined absorption amount based on the gas absorption factor to determine the gas absorption amount; and A given value for the shock absorber size is determined based on the determined gas absorption amount and the determined first value for the shock absorber size.

7. The device according to claim 6, wherein: The processor is configured to: performing a first iteration of the generating process based on the first determined damper load value, including determining a first value for the gas absorption amount; and A second iteration of the generating process is performed based on a second determined damper load value and the first value of the gas absorption amount, the second determined damper load value being greater than the first determined damper load value.

8. The device according to claim 7, wherein: The processor is configured to: The given value of the shock absorber size generated in the second iteration is compared to a predetermined value indicative of a limit of a range of motion of the shock absorber.

9. The device according to any one of claims 1 to 3, wherein: The processor is configured to generate a probability distribution of the shock absorber size based on the generated plurality of shock absorber size values, and to set the minimum value based on the generated probability distribution.

10. The device according to claim 9, wherein: The processor is configured to determine a probability that the value of the damper size is below a given value and to set the minimum value based on the determination of the probability.

11. The device according to any one of claims 1 to 3, wherein: The processor is configured to set a plurality of minimum values ​​for respective sets of values ​​for at least some of the operating characteristics.

12. A system for indicating the status of a shock absorber fitted to an aircraft, the system comprising the device according to claim 11, and the system further comprising: a computer-readable storage medium having stored thereon the plurality of minimum values ​​for the shock absorber size for the corresponding plurality of sets of values; A shock absorber size measuring device, the shock absorber size measuring device is used to obtain a current value of the shock absorber size; one or more instruments for measuring current values ​​of said at least some of said operating characteristics; as well as an indicating device for providing an indication that a current measured value of the shock absorber dimension is less than a minimum value for a first set of values ​​in the plurality of sets of values, wherein The system is configured as follows: identifying the first of the plurality of sets of values ​​based on current measured values ​​of the at least some of the operating characteristics; and A determination is made as to whether the measured damper size is less than a minimum value for the identified first set of values, and the indicating device is caused to provide the indication if the measured damper size is less than the minimum value for the identified first set of values.

13. The system according to claim 12, wherein: The damper dimension measuring device is one of a potentiometer, an electromechanical device, a laser device, and an ultrasonic device.

14. A system according to claim 12 or claim 13, wherein: The processor is configured to update one or more of the probability distributions using current measurements of the set of the plurality of operating characteristics.

15. A method for setting a minimum value of a damper size of a damper of an aircraft landing gear, the damper size indicating an extension of the damper, the method comprising: identifying a respective range of values ​​associated with each of a plurality of operating characteristics at which the shock absorber is operable; identifying a corresponding probability distribution for values ​​of each of the operating characteristics within the identified range; The generation process for generating multiple damper size values ​​is performed by repeatedly performing the following operations: (i) selecting, based on the corresponding probability distribution, a value for each of the operating characteristics as an input to a computer-implemented model for determining a value for the shock absorber size; and (ii) determining a given value for the shock absorber size using the selected value and the computer implemented model; and The minimum value is set based on the generated plurality of damper size values.

16. The method according to claim 15, wherein: The computer implemented model includes a model of the shock absorber size as a function of load on the shock absorber, the plurality of operating characteristics include an aircraft mass and a location of an aircraft center of gravity, and the generating process includes determining the shock absorber loads using the computer implemented model based on a selected aircraft mass and a selected aircraft center of gravity.

17. The method according to claim 16, wherein: The generating process includes selecting a value for the vehicle mass and a value for the vehicle center of gravity based on a predetermined relationship between the vehicle mass and the vehicle center of gravity.

18. The method according to claim 16 or claim 17, wherein: The plurality of operating characteristics includes temperature, and the generating process includes determining a first value for the shock absorber size based on the determined shock absorber load and the selected temperature.

19. The method according to claim 18, wherein: The plurality of operating characteristics includes an amount of fluid lost from the shock absorber, and the generating process includes determining a given value for the shock absorber size based on a selected value for the amount of fluid lost from the shock absorber and the determined first shock absorber size value.

20. The method according to claim 18, wherein: The plurality of operating characteristics includes a gas absorption factor related to absorption of gas contained in the shock absorber into liquid contained in the shock absorber, and the generating process includes: determining an internal pressure of the shock absorber and an internal temperature of the shock absorber based on the selected value of the operating characteristic; determining an absorption amount of the gas into the liquid when the liquid is fully saturated in the liquid at the determined internal pressure and the determined internal temperature; modifying the determined absorption amount based on the gas absorption factor to determine the gas absorption amount; and A given value for the shock absorber size is determined based on the determined gas absorption amount and the determined first value for the shock absorber size.

21. The method according to claim 20, comprising: performing a first iteration of the generating process based on the first determined damper load value, including determining a first value for the gas absorption amount; and A second iteration of the generating process is performed based on a second determined damper load value and the first value of the gas absorption amount, the second determined damper load value being greater than the first determined damper load value.

22. The method according to claim 21, comprising: The given value of the shock absorber size generated in the second iteration is compared to a predetermined value indicative of a limit of a range of motion of the shock absorber.

23. A method according to any one of claims 15 to 17, comprising generating a probability distribution of shock absorber sizes based on the generated plurality of shock absorber size values, and setting the minimum value based on the generated probability distribution.

24. The method of claim 23, comprising determining a probability that the value of the shock absorber size is less than a given value, and setting the minimum value based on the determination of the probability.

25. A method according to any one of claims 15 to 17, comprising setting a plurality of minimum values ​​for respective sets of values ​​of at least some of the operating characteristics.

26. The method according to claim 25, comprising: measuring current values ​​of at least some of the operating characteristics for a shock absorber fitted to the aircraft; identifying a first set of values ​​in the plurality of sets of values ​​based on the identified current value; performing measurement of dimensions of the shock absorber on the aircraft; and A determination is made as to whether the measured damper size is less than a minimum value for the identified first set of values, and if the measured damper size is less than the minimum value for the identified first set of values, an indication is provided that the measured damper size is less than the minimum value for the identified first set of values.

27. The method of claim 26, comprising performing the measuring of the damper dimensions using at least one of a potentiometer, an electromechanical device, a laser device, and an ultrasonic device.

28. A method according to claim 26 or claim 27, comprising updating one or more of the probability distributions using a current measurement of the operating characteristic.

29. A computer program product which, when executed by a processor, causes the processor to perform the method according to any one of claims 15 to 28.

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