Aircraft landing gear cabin door inner profile modification method and aircraft landing gear cabin door

Abstract

The invention discloses an aircraft landing gear cabin door inner profile modification method and an aircraft landing gear cabin door, and belongs to the technical field of aircraft equipment. The aircraft landing gear cabin door inner profile modification method comprises the following steps: firstly, analyzing a resultant force action direction of a tire on a cabin door inner profile, and determining a critical clamping stagnation point and a critical resultant force action direction of the tire on the cabin door inner profile; establishing a rectangular coordinate system, dividing the inner cabin door into a first side line and a second side line, and determining a first function analytic expression according to the first side line; establishing a solving equation of the second function analytic expression, and solving the second function analytic expression according to the first function analytic expression; and finally obtaining the shape of the inner profile of the cabin door by combining the first function analytic expression and the second function analytic expression. According to the aircraft landing gear cabin door inner shape surface modification method and the aircraft landing gear cabin door, the inner shape surface of the cabin door can be smoother, the cabin door can be smoothly jacked open by the landing gear and tires through gravity, and the following actions are completed.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft equipment, and particularly relates to a method for modifying the inner surface of an aircraft landing gear door and an aircraft landing gear door. Background Art

[0002] The main landing gear door of an aircraft is located in the middle fuselage area and at the bottom of the wing-body fairing. It mainly wraps the tires on the main landing gear of the aircraft to prevent the main landing gear and the tires on the main landing gear from being exposed outside the aircraft fuselage and maintain the aerodynamic shape of the aircraft during flight. During the process of the aircraft preparing to land, the main landing gear door needs to be opened, and the main landing gear and the tires on the main landing gear are exposed to complete the landing. Under normal circumstances, the door is driven to open and the main landing gear moves by actuators on the main landing gear and the door. However, in the case of the failure of the actuators on the main landing gear and the door, the main landing gear needs to rely on gravity to push open the door and complete the subsequent actions. In the prior art, referring to Figure 1 , due to the curvature problem of the inner surface of the door 1, the tire 2 on the main landing gear may get stuck during the sliding process along the inner surface of the door 1, causing a series of subsequent problems.

[0003] In the prior art, to address the above problem, a slide rail 11 is usually added at the position where the tire 2 on the main landing gear gets stuck during the sliding process along the inner surface of the door 1. Referring to Figure 2 , the setting of the slide rail 11 makes the position where the tire 2 on the main landing gear gets stuck during the sliding process along the inner surface of the door 1 smoother, so as to achieve the smooth sliding of the tire 2 on the main landing gear along the inner surface of the door 1. However, the setting of the slide rail 11 adds a protrusion to the aerodynamic surface during the landing process of the aircraft and increases the weight additionally, which is not conducive to the landing of the aircraft. In addition, the installation method between the slide rail 11 and the door 1 is generally to install the slide rail 11 after the door 1 is formed. During the later installation process, operations such as potting and inserts are involved, and the process manufacturability is poor.

[0004] Therefore, it is urgent to study a method for modifying the inner surface of an aircraft landing gear door and an aircraft landing gear door to avoid the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for modifying the inner surface of an aircraft landing gear door and an aircraft landing gear door, which can make the inner surface of the door smoother, and then enable the landing gear to smoothly push open the door by relying on gravity in the case of the failure of the actuators on the landing gear and the door, and complete the subsequent actions.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] A method for modifying the inner surface of an aircraft landing gear door. A tire is installed on the aircraft landing gear, and the door is hinged between the aircraft housing. The tire can contact the inner surface of the door and cause the door to rotate relatively. The method for modifying the inner surface of the aircraft landing gear door includes:

[0008] Analyze the forces exerted by the tire on the inner surface of the door, and determine the direction of the resultant force of the forces exerted by the tire on the inner surface of the door.

[0009] Determine the critical jamming point of the tire on the inner surface of the door and the critical resultant force direction.

[0010] Establish a rectangular coordinate system. Set the inner surface on the side where the tire at the critical jamming point on the inner surface of the door can smoothly slide as the first inner surface, and the side line of the first inner surface as the first side line. Set the functional analytic expression of the first side line on the rectangular coordinate system as the first functional analytic expression. The first side line is a known curve, and determine the first functional analytic expression from the first side line.

[0011] Set the inner surface on the side where the tire at the critical jamming point on the inner surface of the door fails to smoothly slide as the second inner surface, and the side line of the second inner surface as the second side line. The functional analytic expression of the second side line on the rectangular coordinate system is the second functional analytic expression. Establish an equation for solving the second functional analytic expression, and solve the second functional analytic expression according to the first functional analytic expression.

[0012] Combine the first functional analytic expression and the second functional analytic expression to obtain the shape of the side line of the inner surface of the door in the rectangular coordinate system, and obtain the shape of the inner surface of the door.

[0013] Preferably, the forces exerted by the tire on the inner surface of the door include:

[0014] The extrusion normal pressure of the tire on the door. The direction of the extrusion normal pressure is along the normal line at the contact point between the tire and the inner surface of the door and points to the side of the door away from the tire.

[0015] The reaction force of the tire on the door. The direction of the reaction force is along the tangent at the contact point between the tire and the inner surface of the door and points to the sliding direction of the tire.

[0016] Set the coefficient of friction between the tire and the inner surface of the door as μ0, set the extrusion normal pressure as F N , set the reaction force as F f , then there is F f = μ0 × F N, set the resultant force of the extrusion normal pressure and the reaction force to be represented as F, the included angle between the acting direction of the resultant force and the normal line at the contact point between the tire and the inner surface of the hatch is the friction angle, and the friction angle is represented as θ, then θ = arctan(F f / F N ) = arctan(μ0).

[0017] Preferably, set the safety factor to be K, then the friction angle θ0 = arctan(KF f / F N ) = arctan(Kμ0).

[0018] Preferably, the critical jamming point is determined by several experiments, and the acting direction of the critical resultant force points to the hinge point between the hatch and the aircraft fuselage along the line connecting the critical jamming point and the hinge point between the hatch and the aircraft fuselage.

[0019] Preferably, the solution equation of the second function analytic formula is established by means of the relationship between the trigonometric function relation and the function and its derivative.

[0020] Preferably, define the hinge point between the hatch and the aircraft fuselage as point M, then the coordinates of point M in the rectangular coordinate system are represented as (x M , y M ), define the critical jamming point as point B, define the first function analytic formula as y = f(x), define the second function analytic formula as y = g(x), take a point E on the second function analytic formula, then the coordinates of point E in the rectangular coordinate system are represented as (x, g(x)), the included angle between the straight line EM and the horizontal line is represented as α, then the slope of the straight line EM, tanα = (g(x) - y M ) / (x - x M );

[0021] The acting direction of the critical resultant force at point E is the same as that of the straight line EM, that is, the included angle between the straight line EM and the normal line at point E is θ0, the included angle between the normal line at point E and the horizontal line is represented as γ, then there is γ = α + θ0, the included angle between the tangent line at point E and the horizontal line is represented as ε, then there is Then there is the slope of the tangent line at point E Combined with tanγ = tan(α + θ0) = (tanα + tanθ0) / (1 - tanαtanθ0),

[0022] The solution equation of the second function analytic formula is established as follows:[[]]

[0023] g′(x) = ((g(x) - y M ) / (x - x M) + Kμ0) / (1 - Kμ0(g(x) - y M ) / (x - x M ))

[0024] The coordinates of point B are obtained from the first function analytical formula, and the second function analytical formula is solved by numerical fitting through point B.

[0025] An aircraft landing gear door is manufactured by the method for modifying the inner surface of the aircraft landing gear door described above. The aircraft landing gear door includes a door, the door has an inner surface, and the function analytical formula of the side line of the inner surface of the door in the rectangular coordinate system is spliced by the first function analytical formula and the second function analytical formula.

[0026] Advantages of the present invention:

[0027] In the present invention, through a method for modifying the inner surface of an aircraft landing gear door, the inner surface of the door is modified and designed. By trimming the part with a larger curvature on the inner surface of the door, the inner surface of the door becomes smoother. Subsequently, in the case where the actuators on the landing gear and the door fail, the landing gear can smoothly push open the door by gravity and complete the subsequent actions. Through the above method, only the second function analytical formula needs to be calculated and determined at the initial stage of design to obtain the shape of the inner surface of the door. Compared with the traditional slide rail design scheme, the inner surface modification design will not add protrusions on the aerodynamic surface and will not increase the weight additionally. In addition, it is integrally formed during the manufacturing process of the door, without involving operation process steps such as potting and inserts, and has good process manufacturability. Description of the drawings

[0028] Figure 1 is a schematic diagram showing the jamming between the door and the tire in the background art of the present invention;

[0029] Figure 2 is a schematic diagram showing the door and the slide rail in the background art of the present invention;

[0030] Figure 3 is the first force analysis diagram of the method for modifying the inner surface of the aircraft landing gear door provided by the present invention;

[0031] Figure 4 is the second force analysis diagram of the method for modifying the inner surface of the aircraft landing gear door provided by the present invention.

[0032] In the figure:

[0033] 1. Door; 11. Slide rail;

[0034] 2. Tire. Detailed implementation manners

[0035] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0036] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0037] Unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] Unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature not being in direct contact but being in contact through other features between them. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature is at a lower horizontal height than the second feature.

[0039] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments.

[0040] As Figure 3 and Figure 4 shown, the present invention provides a method for modifying the inner surface of an aircraft landing gear door and an aircraft landing gear door, which can make the inner surface of the door smoother, and then enable the landing gear to smoothly push open the door by gravity in the case of the failure of the actuators on the landing gear and the door, and complete the subsequent actions.

[0041] In the present invention, a tire 2 is installed on the aircraft landing gear. The cabin door 1 is hinged to the aircraft shell. The tire 2 can contact the inner surface of the cabin door 1 and cause the cabin door 1 to rotate relatively. Specifically, the method for modifying the inner surface of the aircraft landing gear cabin door includes the following steps.

[0042] First, analyze the forces exerted by the tire 2 on the inner surface of the cabin door 1, and determine the direction of the resultant force of the forces exerted by the tire 2 on the inner surface of the cabin door 1.

[0043] Second, determine the critical jamming point of the tire 2 on the inner surface of the cabin door 1 and the direction of the critical resultant force.

[0044] Third, establish a rectangular coordinate system. Set the inner surface on the side where the tire 2 at the critical jamming point on the inner surface of the cabin door 1 can smoothly slide over as the first inner surface, and the side line of the first inner surface as the first side line. Set the function analytical formula of the first side line on the rectangular coordinate system as the first function analytical formula. The first side line is a known curve, and the first function analytical formula is determined from the first side line.

[0045] Fourth, set the inner surface on the side where the tire 2 at the critical jamming point on the inner surface of the cabin door 1 fails to smoothly slide over as the second inner surface, and the side line of the second inner surface as the second side line. The function analytical formula of the second side line on the rectangular coordinate system is the second function analytical formula. Establish an equation for solving the second function analytical formula, and solve the second function analytical formula according to the first function analytical formula.

[0046] Fifth, combine the first function analytical formula and the second function analytical formula to obtain the shape of the side line of the inner surface of the cabin door 1 in the rectangular coordinate system, and obtain the shape of the inner surface of the cabin door 1.

[0047] In the present invention, through a method for modifying the inner surface of the aircraft landing gear cabin door, the inner surface of the cabin door 1 is modified and designed. By cutting the part with a larger curvature on the inner surface of the cabin door 1, the inner surface of the cabin door 1 becomes smoother. Subsequently, in the case where the actuators on the landing gear and the cabin door 1 fail, the landing gear and the tire 2 on the landing gear can smoothly push open the cabin door 1 by gravity and complete the subsequent actions. Through the above method, only the second function analytical formula needs to be calculated and determined at the initial design stage to obtain the shape of the inner surface of the cabin door 1. Compared with the traditional slide rail design scheme, the inner surface modification design will not add protrusions to the aerodynamic surface and will not increase the weight additionally. In addition, it is integrally formed during the manufacturing process of the cabin door 1, and does not involve operation process steps such as potting and inserts, and has good process manufacturability.

[0048] The force exerted by the tire 2 on the inner surface of the hatch door 1 includes the positive extrusion pressure exerted by the tire 2 on the hatch door 1 and the reaction force exerted by the tire 2 on the hatch door 1, wherein the direction of the positive extrusion pressure is along the normal line at the contact point between the tire 2 and the inner surface of the hatch door 1 pointing to the side of the hatch door 1 away from the tire 2, and the positive extrusion pressure generates a door-opening torque. During the sliding process of the tire 2, the direction of the sliding friction force exerted by the hatch door 1 on the tire 2 is along the tangent line at the contact point between the tire 2 and the inner surface of the hatch door 1 away from the sliding direction of the tire 2. According to the relationship between the action force and the reaction force, the direction of the reaction force exerted by the tire on the hatch door 1 is along the tangent line at the contact point between the tire 2 and the inner surface of the hatch door 1 pointing to the sliding direction of the tire 2, and the reaction force exerted by the tire 2 on the hatch door 1 generates a door-closing torque. See. Figure 3 , the friction coefficient between the tire 2 and the inner surface of the hatch 1 is set to μ0, the friction coefficient can be measured by multiple experiments, and the extrusion positive pressure is set to F N , set the reaction force to be expressed as F f , then F f =μ0×F N , the resultant force of the extrusion positive pressure and the reaction force is expressed as F, the angle between the direction of the resultant force and the normal line at the contact point between the tire and the inner surface of the hatch 1 is the friction angle, and the friction angle is expressed as θ, then θ=arctan(F f / F N )=arctan(μ0).

[0049] In this embodiment, the safety factor is set to K, and the friction angle with the safety factor can be expressed as θ0 = arctan (KF f / F N )=arctan(Kμ0).

[0050] The critical stuck point can be determined by several experiments. For the critical resultant force direction, for each point A on the downward trajectory of the tire 2 on the edge of the inner surface of the cabin door 1, a normal line is drawn at point A, and a straight line with an angle of θ0 with the normal line is drawn, which is the resultant force direction of the reaction force and the positive pressure of the extrusion between the tire 2 and the inner surface of the cabin door 1. For example, when it is at point A, the resultant force direction is offset from the hinge point, and the resultant force produces a door-opening torque, so the tire 2 is not stuck at this point; when it is at point C, the resultant force direction is offset from the hinge point, that is, the resultant force produces a door-closing torque, and it is stuck; when it is at point B, it is a critical situation, and the resultant force direction passes through the hinge point. Therefore, the critical resultant force direction points to the hinge point between the cabin door 1 and the aircraft shell along the line connecting the critical stuck point and the hinge point between the cabin door 1 and the aircraft shell.

[0051] In this embodiment, the solution equation for the analytical expression of the second function is established by means of a trigonometric function relationship and a relationship between a function and a derivative function.

[0052] Specifically, refer to Figure 3 and Figure 4 . Define the hinge point between the hatch 1 and the aircraft fuselage as point M. Then the coordinates of point M in the rectangular coordinate system are expressed as (x M , y M ). Define the critical jamming point as point B, define the first function analytic formula as y = f(x), define the second function analytic formula as y = g(x). Take a point E on the second function analytic formula. Then the coordinates of point E in the rectangular coordinate system are expressed as (x, g(x)). The angle between the straight line EM and the horizontal line is expressed as α. Then the slope tanα of the straight line EM = (g(x) - y M ) / (x - x M ).

[0053] The direction of the critical resultant force at point E is consistent with the straight line EM. That is, the angle between the straight line EM and the normal line at point E is θ0. The angle between the normal line at point E and the horizontal line is expressed as γ. Then there is γ = α + θ0. The angle between the tangent line at point E and the horizontal line is expressed as ε. Then there is Then there is the slope of the tangent line at point E Combined with tanγ = tan(α + θ0) = (tanα + tanθ0) / (1 - tanαtanθ0), then establish the following solution equation for the second function analytic formula:

[0054] g′(x) = (((g(x) - y M ) / (x - x M ) + Kμ0) / (1 - Kμ0(g(x) - y M ) / (x - x M )),

[0055] Obtain the coordinates of point B from the first function analytic formula, and solve the second function analytic formula by numerical fitting through point B. Then combine the first function analytic formula and the second function analytic formula to obtain the shape of the inner surface side line of the hatch 1 in the rectangular coordinate system, and obtain the shape of the inner surface of the hatch 1.

[0056] The aircraft landing gear hatch provided by the present invention is obtained by the above-mentioned aircraft landing gear hatch inner surface modification method. The aircraft landing gear hatch includes a hatch 1. The hatch 1 has an inner surface. The function analytic formula of the side line of the inner surface of the hatch 1 in the rectangular coordinate system is spliced by the first function analytic formula and the second function analytic formula. For the aircraft landing gear hatch provided by the present invention, the shape is determined according to the first function analytic formula and the second function analytic formula, so that the inner surface of the hatch 1 is smoother. Then, in the case where the actuators on the landing gear and the hatch 1 fail, the landing gear can smoothly push open the hatch 1 by gravity and complete the subsequent actions.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A method for modifying the inner surface of an aircraft landing gear door. A tire (2) is installed on the aircraft landing gear. The door (1) is hinged between the aircraft housing. The tire (2) can contact the inner surface of the door (1) and cause the door (1) to rotate relatively. It is characterized in that, The method for modifying the inner surface of the aircraft landing gear door includes: Analyze the forces exerted by the tire (2) on the inner surface of the door (1), and determine the direction of the resultant force of the forces exerted by the tire (2) on the inner surface of the door (1); Determine the critical jamming point of the tire (2) on the inner surface of the door (1) and the critical resultant force direction; Establish a rectangular coordinate system. Set the inner surface on the side where the tire (2) at the critical jamming point on the inner surface of the door (1) can smoothly slide as the first inner surface, and the side line of the first inner surface as the first side line. Set the functional analytic expression of the first side line on the rectangular coordinate system as the first functional analytic expression. The first side line is a known curve, and determine the first functional analytic expression from the first side line; Set the inner surface on the side where the tire (2) at the critical jamming point on the inner surface of the door (1) fails to smoothly slide as the second inner surface, and the side line of the second inner surface as the second side line. The functional analytic expression of the second side line on the rectangular coordinate system is the second functional analytic expression. Establish the solving equation of the second functional analytic expression, and solve the second functional analytic expression according to the first functional analytic expression; Combine the first functional analytic expression and the second functional analytic expression to obtain the shape of the side line of the inner surface of the door (1) in the rectangular coordinate system, and obtain the shape of the inner surface of the door (1).

2. The method for modifying the internal profile of the aircraft landing gear door according to claim 1, characterized in that, The forces exerted by the tire (2) on the inner surface of the door (1) include: The extrusion normal pressure of the tire (2) on the door (1), and the direction of the extrusion normal pressure is along the normal line at the contact point between the tire (2) and the inner surface of the door (1) and points to the side of the door (1) away from the tire (2); The reaction force of the tire (2) on the door (1), and the direction of the reaction force is along the tangent at the contact point between the tire (2) and the inner surface of the door (1) and points to the sliding direction of the tire (2); Set the coefficient of friction between the tire (2) and the inner surface of the hatch (1) as μ0, and set the extrusion normal pressure as F N , and set the reaction force as F f , then there is F f = μ0 × F N , set the resultant force of the extrusion normal pressure and the reaction force as F, and the angle between the acting direction of the resultant force and the normal line at the contact point between the tire (2) and the inner surface of the hatch (1) as the friction angle, and the friction angle is expressed as θ, then θ = arctan(F f / F N ) = arctan(μ0).

3. The method for modifying the internal profile of the aircraft landing gear door according to claim 2, characterized in that Set the safety factor as K, then the friction angle θ0 = arctan(KF f / F N ) = arctan(Kμ0).

4. The method for modifying the inner surface of the aircraft landing gear door according to claim 3, characterized in that The critical jamming point is determined by several experiments, and the critical resultant force direction points to the hinge point between the door (1) and the aircraft shell along the connection line between the critical jamming point and the hinge point between the door (1) and the aircraft shell; 5. The method for modifying the inner surface of the aircraft landing gear door according to claim 4, characterized in that The solving equation of the second functional analytic expression is established by means of the trigonometric function relation and the relationship between the function and the derivative function; 6. The method for modifying the inner surface of an aircraft landing gear door according to claim 5, characterized in that Define the hinge point between the hatch (1) and the aircraft fuselage as point M. Then the coordinates of point M in the rectangular coordinate system are expressed as (x M , y M ). Define the critical jamming point as point B, define the first function analytic expression as y = f(x), define the second function analytic expression as y = g(x). Take a point E on the second function analytic expression. Then the coordinates of point E in the rectangular coordinate system are expressed as (x, g(x)). The angle between the straight line EM and the horizontal line is expressed as α. Then the slope tanα of the straight line EM = (g(x) - y M ) / (x - x M ); The acting direction of the critical resultant force at point E is consistent with the straight line EM, that is, the angle between the straight line EM and the normal line at point E is θ0. The angle between the normal line at point E and the horizontal line is denoted as γ, then γ = α + θ0. The angle between the tangent line at point E and the horizontal line is denoted as ε, then Then there is the slope of the tangent line at point E Combined with tanγ = tan(α + θ0) = (tanα + tanθ0) / (1 - tanαtanθ0), The solving equation of the second functional analytic expression is as follows: g′(x) = ((g(x) - y M ) / (x - x M ) + Kμ0) / (1 - Kμ0(g(x) - y M ) / (x - x M )) Obtain the coordinates of point B from the first functional analytic expression, and solve the second functional analytic expression by numerical fitting through point B; 7. An aircraft landing gear door, characterized in that, The aircraft landing gear door is manufactured by the method for modifying the inner surface of the aircraft landing gear door according to any one of claims 1-6. The aircraft landing gear door includes a door (1), the door (1) has an inner surface, and the functional analytic expression of the side line of the inner surface of the door (1) in the rectangular coordinate system is spliced by the first functional analytic expression and the second functional analytic expression.

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