A method for calculating the landing load of a swing arm landing gear

Abstract

The application relates to a method for measuring and calculating the parking load of a swing arm type landing gear, and belongs to the field of airplane landing gear ground load calculation. The function relationship formula of the ground load, the buffer axial load and the swing arm rotation angle is derived, a few parameters including the measured internal air pressure of the landing gear buffer, the angle between the swing arm and the strut, the landing gear geometric parameters under the full extension state of the buffer are taken as the basis, the landing gear parking load under different airplane weights and gravity centers can be obtained through rapid conversion, and the problems of high difficulty, high cost and long time in the prior art for measuring the parking load are solved.

Description

Technical Field

[0001] This invention relates to the field of aircraft landing gear ground load calculation, and more particularly to a method for calculating the ground stopping load of rocker arm landing gear. Background Technology

[0002] Landing gear stopping load refers to the ground-based support reaction force that the landing gear bears when the aircraft is stationary. Aircraft typically have multiple landing gears, and the stopping load of each landing gear is related to parameters such as the aircraft's weight and center of gravity. Therefore, obtaining the measured stopping load of each landing gear is of significant value and importance for understanding the actual aircraft weight, center of gravity position, and load distribution of each landing gear.

[0003] Landing gear structures include frame-type landing gear, strut-type landing gear, rocker arm-type landing gear, and trolley-type landing gear. Frame-type landing gear is gradually being phased out by modern aircraft because it cannot be retracted. Trolley-type landing gear is mainly used in large transport aircraft. Most modern aircraft typically use strut-type or rocker arm-type landing gear with hydraulic shock absorbers.

[0004] The load transfer path of a strut-type landing gear is clear and has a constant load transfer coefficient, making the calculation of its stopping load simple and clearly defined in various documents and regulations. However, the calculation of the stopping load for a rocker-arm landing gear differs from that of a strut-type landing gear. Its load transfer coefficient changes with the amount of shock absorber compression, and currently there are no relevant standards or regulations specifying this, nor are there any publicly available patents or papers introducing related calculation methods.

[0005] Existing conventional methods for measuring landing gear parking loads mainly involve jacking and weighing or using a weighbridge. This involves using a jack combined with a load sensor or a towing vehicle to move the aircraft to a ground-based weighbridge for weighing. Both methods have stringent requirements: firstly, they require a large open space (such as a hangar or large factory building); secondly, they require specialized equipment (such as load sensors and data acquisition and processing systems, or towing vehicles and large, dedicated weighbridges for aircraft weighing). This results in the high difficulty, cost, and time required for implementing conventional measurement methods. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method for calculating the ground stopping load of a rocker arm landing gear, in order to solve the problem of difficulty in measuring the stopping load of existing landing gears.

[0007] On one hand, embodiments of the present invention provide a method for calculating the stopping load of a rocker arm landing gear, the method comprising:

[0008] Obtain the landing gear geometry parameters in the fully extended state of the buffer;

[0009] The functional relationship between ground load, buffer axial load and rocker arm rotation angle under landing gear shutdown state is obtained based on the torque balance principle.

[0010] In the stopped state, the internal air pressure of the buffer is measured, and then the axial load of the buffer is calculated. The angle between the rocker arm and the vertical line and the angle between the rocker arm and the support are measured. Based on the angle between the rocker arm and the vertical line and the angle between the rocker arm and the support, the rotation angle of the rocker arm is obtained.

[0011] The axial load of the buffer is calculated by substituting the axial load of the buffer and the rotation angle of the rocker arm into the functional relationship, which is the stopping load.

[0012] Based on a further improvement to the above method, the landing gear geometric parameters in the fully extended state of the buffer include:

[0013] The length of the distance from the hinge point of the buffer and the support to the center of rotation of the rocker arm.

[0014] The length of the distance from the hinge point of the buffer and the rocker arm to the center of rotation of the rocker arm.

[0015] Rocker arm length,

[0016] The angle between the line connecting the hinge point of the buffer and the support and the center of rotation of the rocker arm, and the angle between the line connecting the hinge point of the buffer and the center of rotation of the rocker arm.

[0017] Based on a further improvement of the above method, the method of obtaining the landing gear geometry parameters in the fully extended state of the buffer includes: measuring with a measuring tool or reading preset parameters.

[0018] Based on a further improvement of the above method, the "stopping state" refers to the landing gear rocker arm reaching a state of torque balance around the strut's rotation center, expressed as the following relationship:

[0019] F w ·L w -F s ·L s =O, where,

[0020] F W For ground load,

[0021] L W For ground load lever arm,

[0022] F S For the axial load of the buffer,

[0023] L S This is the axial load arm of the buffer.

[0024] Based on a further improvement of the above method, the ground load lever arm is expressed as:

[0025]

[0026] Point O is the center of rotation of the rocker arm around the support.

[0027] C′ is the center point of the wheel axle on the rocker arm when the machine is stopped.

[0028] OC′ is the length of the rocker arm.

[0029] The angle between the rocker arm and the vertical line when the buffer is fully extended.

[0030] This represents the rotation angle of the rocker arm.

[0031] Based on a further improvement of the above method, the axial load arm of the buffer is expressed as:

[0032]

[0033] Point A is the hinge point between the buffer and the support.

[0034] Point B is the hinge point between the buffer and the rocker arm.

[0035] OA is the length of the distance from the hinge point between the buffer and the support to the center of rotation of the rocker arm.

[0036] OB is the distance from the hinge point of the buffer and the rocker arm to the center of rotation of the rocker arm.

[0037] Based on a further improvement of the above method, the functional relationship between the ground load, the buffer axial load, and the rotation angle of the rocker arm is expressed as:

[0038]

[0039] Based on a further improvement of the above method, the calculation of the buffer axial load is expressed as the formula:

[0040] F s =p×A, where,

[0041] P represents the internal air pressure of the buffer, which is measured by a pressure sensor.

[0042] A represents the compressed air area of ​​the buffer.

[0043] Based on a further improvement of the above method, the angle between the rocker arm and the vertical line, and the angle between the rocker arm and the support column, are obtained by measuring the angle displacement sensor.

[0044] Based on a further improvement to the above method, the specific method for obtaining the rocker arm rotation angle based on the angle between the rocker arm and the vertical line and the angle between the rocker arm and the support is as follows:

[0045] The rocker arm rotation angle is obtained by subtracting the angle between the rocker arm and the support column from the angle between the rocker arm and the vertical line when the buffer is in its fully extended state.

[0046] Compared with the prior art, the present invention can achieve at least the following beneficial effects:

[0047] This invention is not limited by site conditions, requires no complex tooling or equipment, and does not require lifting or towing the aircraft. Instead, it directly uses sensing and measuring devices equipped on the landing gear to measure parameters such as the internal air pressure of the landing gear and the rocker arm angle of the strut. Then, through simple conversion relationships, the parameters can be converted to quickly obtain the landing gear stopping load under different aircraft weights and centers of gravity. The calculation process is simple and reliable, and the calculation results are detailed and accurate, which can truly reflect the actual stopping load of the landing gear.

[0048] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0049] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0050] Figure 1 Schematic diagram of the installation position of the sensing and measuring device on the rocker arm landing gear

[0051] Figure 2 Schematic diagram of signal acquisition and processing principle for rocker arm landing gear stopping load calculation system

[0052] Figure 3 Schematic diagram of rocker arm landing gear geometry

[0053] Figure 4 Flowchart of rocker arm landing gear parking load calculation

[0054] Figure 5 Schematic diagram of a rocker arm landing gear structure for a certain type of aircraft

[0055] Figure label:

[0056] 1-Support strut; 2-Damper; 3-Rocker arm; 4-Tire; 5-Angular displacement sensor; 6-Pressure sensor; 7-Aircraft fuselage; A-Hinge point between damper 2 and support strut 1; B-Hinge point between damper 2 and rocker arm 3; C-Center point of the wheel axle on rocker arm 3; O-Rocker arm 3 rotation center. Detailed Implementation

[0057] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0058] A specific embodiment of the present invention discloses a method for calculating the stopping load of a rocker arm landing gear, the method comprising:

[0059] Obtain the landing gear geometry parameters in the fully extended state of the buffer;

[0060] The functional relationship between ground load, buffer axial load and rocker arm rotation angle under landing gear shutdown state is obtained based on the torque balance principle.

[0061] In the stopped state, the internal air pressure of the buffer is measured, and then the axial load of the buffer is calculated. The angle between the rocker arm and the vertical line and the angle between the rocker arm and the support are measured. Based on the angle between the rocker arm and the vertical line and the angle between the rocker arm and the support, the rotation angle of the rocker arm is obtained.

[0062] Substituting the axial load of the buffer and the rotation angle of the rocker arm into the functional relationship, the ground load is calculated, which is the shutdown load.

[0063] Compared with the prior art, the method for calculating the parking load of the rocker arm landing gear provided in this embodiment does not require traditional jacking or weighbridge measurement methods and auxiliary equipment. It can measure and output data in real time when the aircraft is parked, which is convenient and fast.

[0064] like Figure 1 As shown, in a specific embodiment of the present invention, a typical structure of a rocker-arm landing gear is included, specifically comprising: a strut 1, a buffer 2, a rocker arm 3, and a tire 4. The strut 1 is hinged to the buffer 2 and the rocker arm 3, respectively. The rocker arm 3 is connected to the tire 4 and is capable of rotating and displacing around its respective hinge point as the load changes.

[0065] Specifically, a pressure sensor 6 is installed on the buffer 2 to measure the air chamber pressure inside the buffer 2, and an angular displacement sensor 5 is installed between the support 1 and the rocker arm 3 to measure the angle between the rocker arm 3 and the support 1.

[0066] like Figure 2 As shown, the measurements obtained by the sensors are processed by the onboard data acquisition and processing module to calculate the landing gear stopping load, and the results are finally transmitted to the flight control system and the onboard maintenance system for use. The principle of signal acquisition and processing is as follows: Figure 2 As shown.

[0067] Figure 3 A schematic diagram of the geometry of a rocker-arm landing gear is shown.

[0068] like Figure 4As shown, when the landing gear is in a stopped state, the specific process for calculating the stop load is as follows:

[0069] Step S1: Obtain the landing gear geometry parameters in the fully extended state of the buffer.

[0070] Furthermore, the landing gear geometry parameters in the fully extended state of the buffer include:

[0071] The length of the distance from the hinge point between the buffer and the support to the center of rotation of the rocker arm.

[0072] The length of the distance from the hinge point of the buffer and the rocker arm to the center of rotation of the rocker arm.

[0073] Rocker arm length,

[0074] The initial angle between the line connecting the hinge point of the buffer and the support and the center of rotation of the rocker arm, and the line connecting the hinge point of the buffer and the center of rotation of the rocker arm.

[0075] Specifically, such as Figure 3 As shown, point O is the rotation center of rocker arm 2, point A is the hinge point between buffer 2 and support 1, point B is the hinge point between buffer 2 and rocker arm 3, and point C is the center point of the wheel axle on rocker arm 3.

[0076] B′ and C′ are the hinge point between the buffer 2 and the rocker arm 3 and the center point of the wheel axle on the rocker arm 3, respectively, when the machine is stopped.

[0077] Specifically, the stopped state indicates the new position of the hinge point A between the buffer 2 and the rocker arm 3, and the center point of the wheel axle on the rocker arm 3 after rotational displacement following a change in the landing gear load;

[0078] AB and AB′ represent the lengths of buffer 2, OA represents the distance from the hinge point A between buffer 2 and support 1 to the rotation center O of the rocker arm, OB and OB′ represent the distance from the hinge point B between buffer 2 and rocker arm 3 to the rotation center O of the rocker arm, and OC and OC′ represent the lengths of rocker arm 3. The angle between the rocker arm 3 and the vertical line when the buffer 2 is fully extended. Let F be the rotation angle of rocker arm 3. w For ground load, F s The axial load of buffer 2 is in the stopped state.

[0079] Furthermore, the values ​​of OA, OB, OC, and ∠AOB can be obtained through the landing gear preset parameters, which can be obtained from the landing gear factory parameters; or they can be obtained by measuring tools, preferably such as laser rangefinders, protractors, and rangefinder rulers.

[0080] Step S2: Based on the torque balance principle, obtain the functional relationship between the ground load, the axial load of the buffer, and the rocker arm rotation angle when the landing gear is stopped.

[0081] Furthermore, the aforementioned shutdown state refers to the landing gear rocker arm reaching torque equilibrium around the strut's rotation center, expressed as the following formula:

[0082] F w ·L w -F s ·L s =O, where,

[0083] F W For ground load,

[0084] L W For ground load lever arm,

[0085] F S For the axial load of the buffer,

[0086] L S This is the axial load arm of the buffer.

[0087] Specifically, a force analysis is performed on the landing gear, and the torque is balanced at point O, i.e.

[0088] F w ·L w -F s ·L s =O.

[0089] Furthermore, the ground load lever arm lever arm L s =h′;

[0090] In ΔAOB′,

[0091] According to geometric relationships, OC = OC′, OB = OB′

[0092] Furthermore,

[0093] Furthermore, in the shutdown state, the relationship between the shutdown load and the axial load of buffer 2 is as follows:

[0094]

[0095] Substituting the values ​​of OA, OB, OC, and ∠AOB under the fully extended state of buffer 2 into the above formula, it simplifies to the axial load F of buffer 2. W With ground load F S Rotation angle of rocker arm 3 The functional relationship.

[0096] Step S3: In the stopped state, measure the internal air pressure of the buffer, and then calculate the axial load of the buffer. Measure the angle between the rocker arm and the vertical line, and the angle between the rocker arm and the support column. Based on the angle between the rocker arm and the vertical line, and the angle between the rocker arm and the support column, obtain the rocker arm rotation angle.

[0097] Specifically, the axial load of buffer 2 is calculated, expressed as the formula: F s =P×A, where,

[0098] P represents the internal air pressure of buffer 2, which is obtained by measuring a pressure sensor.

[0099] A represents the air pressure area of ​​buffer 2, which is obtained by reading preset parameters.

[0100] Specifically, the method of obtaining the rotation angle of the rocker arm 3 based on the angle between the rocker arm 3 and the vertical line and the angle between the rocker arm 3 and the support column 1 is as follows:

[0101] The rotation angle of the rocker arm 3 is obtained by subtracting the angle between the rocker arm 3 and the support column 1 from the angle between the rocker arm 3 and the vertical line when the buffer 2 is in its fully extended state.

[0102] Specifically, the angle between the rocker arm 3 and the vertical line when the buffer 2 is in its fully extended state. And the angle between rocker arm 3 and support column 1 when the machine is stopped. Subtracting the two gives the rotation angle of the rocker arm.

[0103] Furthermore, the angles between the rocker arm and the vertical line, and between the rocker arm and the support column, are measured using an angular displacement sensor.

[0104] Specifically, the rocker arm 3 rotation angle is obtained by measuring the angle between the rocker arm 3 and the support column 1 using the angular displacement sensor 5 when the machine is stopped.

[0105] Step S4: Substitute the axial load of the buffer and the rotation angle of the rocker arm into the functional relationship to calculate the ground load, which is the shutdown load.

[0106] Specifically, the axial load F of the buffer S Rotation angle of load rocker arm Substituting into the functional relationship ξ1, we obtain the shutdown load F. W .

[0107] Figure 5 A specific embodiment of the present invention using a rocker arm landing gear of a certain type of aircraft is shown. The geometric parameters of the landing gear are measured in the fully extended state of the buffer, and the measurement results are recorded as shown in Table 1. The fully extended state of the buffer refers to the initial state of the buffer 2 without any compression.

[0108] Table 1 Summary of landing gear geometric parameters

[0109]

[0110]

[0111] Substituting the above parameter values ​​into the formula, we can obtain the functional relationship. for:

[0112]

[0113] With the system shut down, pressure sensor 6 measured the internal air pressure P of buffer 2 to be 5.43 MPa, and the compressed air area A of buffer 2 was 0.0053 m². 2 .

[0114] Then, the axial load F of buffer 2 s =P×A=6.11×10 6 ×0.0053=32383N.

[0115] With the machine stopped, the angle between the rocker arm 3 and the vertical line is measured using the angular displacement sensor 5, and its value is compared with... Subtracting the two, we get the rocker arm's 3-angle rotation. It is 27.4°.

[0116] F s and Substituting the value into the functional relationship ξ1, we get

[0117]

[0118] The ground load of the landing gear was measured to be 19868.9 N using a weighing scale. The ground load obtained by the technical solution of this invention differs from the conventional measured value by only 0.4%. This shows that the ground load value obtained by this method is accurate and reliable, and can truly reflect the actual stopping load of the landing gear.

[0119] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0120] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the stopping load of a rocker arm landing gear, characterized in that, The method includes: Obtain the landing gear geometry parameters in the fully extended state of the buffer, including: The length of the distance from the hinge point of the buffer and the support to the center of rotation of the rocker arm. The length of the distance from the hinge point of the buffer and the rocker arm to the center of rotation of the rocker arm. Rocker arm length, The angle between the line connecting the buffer and the hinge point of the support column and the rotation center of the rocker arm, and the angle between the line connecting the buffer and the hinge point of the rocker arm and the rotation center of the rocker arm. Methods for obtaining the landing gear geometry parameters in the fully extended state of the buffer include measuring with gauges or reading preset parameters; Based on the principle of torque balance, the functional relationship between ground load, buffer axial load, and rocker arm rotation angle in the landing gear shutdown state is obtained. Here, the shutdown state refers to the rocker arm reaching torque balance around the strut's rotation center, expressed as the following relationship: In the formula, F W For ground load, L W The ground load lever arm is represented as: In the formula, Point O is the center of rotation of the rocker arm around the support column. The center point of the wheel axle on the rocker arm when the machine is stopped. The length of the rocker arm, The angle between the rocker arm and the vertical line when the buffer is fully extended. The rotation angle of the rocker arm. F S For the axial load of the buffer, L S The axial load arm of the buffer is expressed as: In the formula, Point A is the hinge point between the buffer and the support. Point B is the hinge point between the buffer and the rocker arm. OA is the length of the distance from the hinge point between the buffer and the support to the center of rotation of the rocker arm. OB is the distance from the hinge point of the buffer and the rocker arm to the center of rotation of the rocker arm; The functional relationship between the ground load, the axial load of the buffer, and the rotation angle of the rocker arm is expressed as: ； With the machine stopped, the internal air pressure of the buffer is measured, and then the axial load of the buffer is calculated. The angles between the rocker arm and the vertical line, and between the rocker arm and the support are measured. Based on the angles between the rocker arm and the vertical line, and between the rocker arm and the support, the rotation angle of the rocker arm is obtained. The calculation of the axial load of the buffer is expressed as the formula: In the formula, P represents the internal air pressure of the buffer, which is measured by a pressure sensor. A represents the compressed air area of ​​the buffer; The specific method for obtaining the rocker arm rotation angle based on the angle between the rocker arm and the vertical line and the angle between the rocker arm and the support column is as follows: The rocker arm rotation angle is obtained by subtracting the angle between the rocker arm and the support column from the angle between the rocker arm and the vertical line when the buffer is in its fully extended state. The ground load, calculated by substituting the axial load of the buffer and the rotation angle of the rocker arm into the functional relationship, is the shutdown load.

2. The method for calculating the stopping load of a rocker arm landing gear according to claim 1, characterized in that, The angles between the rocker arm and the vertical line, and between the rocker arm and the support column, are measured by an angular displacement sensor.

Images