Undercarriage, design method thereof and aircraft

Abstract

The invention discloses an undercarriage and a design method thereof, and an aircraft, and relates to the technical field of undercarriages, the undercarriage comprises at least two skids, at least two buffer beams and at least two mounting brackets, the two skids are oppositely arranged, the buffer beams are connected with the two skids and are upwards convexly arranged, each buffer beam is provided with a transverse straight beam section and two bent beam sections, and the transverse straight beam sections and the two bent beam sections are oppositely arranged. The bent beam section is connected between the transverse straight beam section and the skid; the installation supports are used for being connected with an aircraft body, the two installation supports are arranged at the two opposite ends of one transverse straight beam section respectively, the distance between the two installation supports is d, the width of the undercarriage in the distribution direction of the installation supports is D, and d / D is larger than or equal to 0.3 and smaller than or equal to 0.7. According to the technical scheme, the buffering and energy absorbing effects of the undercarriage can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of landing gears, and in particular to a landing gear and a design method thereof, and an aircraft. Background Art

[0002] As a buffering and energy-absorbing structure of an aircraft, the structural stability and mechanical properties of the landing gear play a key role. A skid-type landing gear usually includes two skids and two arched beams distributed at the front and rear ends of the skids. The arched beams are usually arranged to protrude upward, and the middle part is connected to the aircraft body through a mounting bracket, and the ends are connected to the skids. However, the arched beams usually only play the role of transferring loads and cannot effectively absorb energy. Therefore, how to improve the buffering and energy-absorbing effect of the arched beams and the mounting brackets is a problem that urgently needs to be solved in this field. Summary of the invention

[0003] The main purpose of the present invention is to provide a landing gear and a design method thereof, and an aircraft, aiming to improve the buffering and energy absorption effect of the landing gear.

[0004] To achieve the above object, the landing gear proposed by the present invention comprises:

[0005] There are at least two slides, and the two slides are arranged opposite to each other;

[0006] at least two buffer beams are provided, the buffer beams connect the two slides and protrude upward, the buffer beams have a transverse beam section capable of elastic deformation and two curved beam sections, the curved beam sections are connected between the transverse beam section and the slide; and

[0007] At least two mounting brackets are used to connect the aircraft body, the two mounting brackets are arranged at opposite ends of a horizontal beam section, and the spacing between the two mounting brackets is d, the width of the landing gear in the distribution direction of the mounting brackets is D, 0.3≤d / D≤0.7.

[0008] In one embodiment, 0.45≤d / D≤0.5.

[0009] In one embodiment, at least two of the buffer beams include a front beam and a rear beam, and the transverse and vertical beam sections of the front beam and the rear beam are each provided with at least two mounting brackets, the rear beam is close to the center of gravity of the aircraft, and the d / D value on the rear beam is smaller than the d / D value on the front beam.

[0010] In one embodiment, at least two of the buffer beams include a front beam, and a curved beam section of the front beam is bent and extended outwardly toward the rear and butts against the front end of the slide.

[0011] In one embodiment, a front warping section is extended from the front end of the slide toward the upper front side, and the front warping section protrudes outward and is connected to the curved beam section of the front beam.

[0012] In one embodiment, a rear warping section is extended from the rear end of the slide toward the rear and upward side, and the radii of the rear warping section, the front warping section and the curved beam section are configured to be the same.

[0013] In one embodiment, the rear warping section, the front warping section and the curved beam section are formed and arranged by a bending machine, and the bending radius is configured to be the same.

[0014] In one embodiment, the landing gear further includes a first joint, the front beam and the slide are respectively inserted at opposite ends of the first joint, and the front beam and / or the slide are fixedly connected to the first joint via a connecting member.

[0015] In one embodiment, the ratio of the depth of the front beam inserted into the first joint to the diameter of the front beam ranges from 1 to 2.

[0016] In one embodiment, the ratio of the depth of the slide inserted into the first joint to the diameter of the slide ranges from 1 to 2.

[0017] In one embodiment, the buffer beam is made of spring steel, and the slide is made of deformed aluminum alloy.

[0018] In one embodiment, the buffer beam and / or the skid is a tubular structure, and the cross-section is circular, elliptical or polygonal.

[0019] In one embodiment, the landing gear further comprises an anti-wear sheet, and the anti-wear sheet is arranged on the lower side of the skid.

[0020] In one embodiment, at least two of the buffer beams include a rear beam, and the landing gear also includes a second joint, the second joint is provided with a socket and a buckle groove, the end of the rear beam is inserted into the socket and fixed by bolts, and the buckle groove is buckled on the upper side of the skid and fixed by rivets.

[0021] In one embodiment, the mounting bracket includes a mounting seat and a stop structure, the mounting seat is connected to the aircraft body, and the stop structure connects the mounting seat and the buffer beam to limit the mounting seat from detaching from the buffer beam in the up and down directions.

[0022] In one embodiment, the side wall of the mounting seat is provided with a downwardly notched yielding groove, and the anti-slip structure includes an anti-slipping boss, an installation boss and a locking member, the anti-slipping boss is extended outward from the notch edge of the yielding groove, the installation boss is installed on the buffer beam, the yielding groove can be sleeved on the installation boss from top to bottom, and the locking member is detachably installed on the installation boss and abuts against the upper side of the anti-slipping boss.

[0023] In one embodiment, the mounting boss is a stud, and the locking member includes a nut and an anti-slip washer. The nut is locked on the mounting boss, and the anti-slip washer is clamped on the mounting seat, and the anti-slip washer abuts against the upper side of the anti-slip boss.

[0024] In one embodiment, the nut is a slotted nut, and the slotted nut is fixed relative to the stud in the circumferential direction by a cotter pin.

[0025] In one embodiment, the connection gap between the nut and the stud is filled with protective glue.

[0026] In one embodiment, the mounting bracket also includes a clamp, which includes a first clamp body and a second clamp body connected to each other, the first clamp body and the second clamp body jointly clamp the buffer beam and enable the clamp to rotate around an axis extending in the left and right directions; the first clamp body is arranged above the second clamp body and is used to connect the aircraft body.

[0027] In one embodiment, the mechanical strength of the first hoop body is greater than that of the second hoop body.

[0028] In one embodiment, the first hoop body and the second hoop body are provided with reinforcing ribs, and the reinforcing ribs surround the outer circumference of the clamp along the front-rear direction of the landing gear. The number of reinforcing ribs on the first hoop body is greater than the number of reinforcing ribs on the second hoop body, and the multiple reinforcing ribs on the first hoop body are arranged along the left-right direction of the landing gear.

[0029] In one embodiment, the landing gear further includes a limit bracket, which is disposed on the buffer beam and cooperates with the mounting bracket to limit the lateral displacement of the mounting bracket.

[0030] In one embodiment, two limiting brackets are provided and are located at the interval between two mounting brackets on the same buffer beam, and the limiting bracket abuts against the end surface of the mounting bracket close to the other mounting bracket.

[0031] In one embodiment, the limiting bracket is configured as a clamp and is arranged on the peripheral side surface of the buffer beam.

[0032] In one embodiment, the mounting bracket has a mounting channel, the buffer beam is inserted into the mounting channel, and the landing gear further includes an elastically deformable shock-absorbing pad, which is arranged between the side wall surface of the mounting channel and the peripheral side surface of the buffer beam.

[0033] In one embodiment, a stop flange extends inwardly from the end surface of the installation channel, and the inner end surface of the stop flange abuts against the end surface of the shock-absorbing pad.

[0034] In one embodiment, the mounting bracket has a mounting channel, the buffer beam is inserted into the mounting channel, a stop flange is extended inwardly from the end surface of the mounting channel, and the outer end surface of the stop flange abuts against the limit bracket.

[0035] The present invention also provides a landing gear design method, comprising the steps of:

[0036] Constructing an initial wireframe model of the landing gear; wherein the initial wireframe model includes two skids of the landing gear and a buffer beam connected between the two skids, the buffer beam includes a transverse beam section and a curved beam section, the curved beam section is connected between the transverse beam section and the skid, two fuselage mounting points are respectively arranged at opposite ends of the transverse beam section, and the distance between the two fuselage mounting points is d;

[0037] Constructing a primary simulation model of the landing gear according to the initial wireframe model, and performing mechanical analysis and modal analysis;

[0038] If the results of the mechanical analysis and modal analysis of the primary simulation model meet the requirements, the primary simulation model is judged to be qualified;

[0039] If not, the primary simulation model is optimized and iterated until the analysis result meets the requirements;

[0040] The value of the distance d is determined according to a qualified primary simulation model.

[0041] In one embodiment, the landing gear design method further comprises the steps of:

[0042] The landing gear design method further comprises the steps of:

[0043] According to the primary simulation model and the connection structure connecting the skid and the buffer beam, a secondary simulation model of the landing gear is constructed; wherein the bending radius of the bending beam section of the secondary simulation model is R G ;

[0044] Perform a drop simulation analysis on the secondary simulation model to determine the minimum bending radius R of the curved beam segment. Gm ; Wherein, the bending radius R G Greater than the minimum bending radius RGm .

[0045] In one embodiment, the skid of the secondary simulation model is provided with a rear warping section at the rear end, and the bending radius of the rear warping section is R R ;

[0046] The step of performing a drop shock simulation analysis on the secondary simulation model is also used to determine the minimum unyielding radius R of the rear warping section of the landing gear when the landing gear is flipped over at a later angle. Rm ; Wherein, the bending radius R R Greater than the minimum unyielding radius R Rm .

[0047] In one embodiment, the slide of the secondary simulation model is provided with a front warping section at the front end, and the bending radius of the front warping section is R F ;

[0048] The step of performing drop simulation analysis on the secondary simulation model is also used to determine the minimum bending radius R of the front warping section. Fm ; Wherein, the bending radius R F Greater than the minimum bending radius R Fm .

[0049] In one embodiment, the bending radius R G , bending radius R R and bending radius R F The value of is the same and is greater than the minimum bending radius R Gm , minimum unyielding radius R Rm and minimum bending radius R Fm The largest one among them.

[0050] In one embodiment, the step of performing a drop shock simulation analysis on the secondary simulation model is also used to obtain stress results of the landing gear and absorption results of the multi-stage energy absorption structure, and determine whether the secondary simulation model is qualified according to the stress results and the absorption results;

[0051] Among them, the multi-level energy absorption structure includes a first-level absorption structure formed by the bending deformation of the horizontal beam section, a second-level absorption structure formed by the bending deformation of the curved beam section, and a third-level absorption structure formed by the bending deformation of the front warping section. The energy absorption amount of the first-level absorption structure is E1, the energy absorption amount of the second-level absorption structure is E2, and the energy absorption amount of the third-level absorption structure is E3.

[0052] The present invention further provides an aircraft, comprising an aircraft body and the aforementioned landing gear, wherein the landing gear is arranged on the lower side of the aircraft body.

[0053] In the technical solution of the present invention, firstly, in addition to transmitting the load, the buffer beam can also absorb the impact load through the elastic deformation of the horizontal and vertical beam sections and the curved beam sections, thereby playing an effective energy absorption role, thereby improving the buffering and energy absorption effect of the landing gear. Secondly, by maximizing the distance between the two mounting brackets located on the same buffer beam, on the one hand, the length of the deformable part in the middle of the buffer beam (i.e., the horizontal and vertical beam sections) can be increased, which is beneficial to improving the buffering and energy absorption effect of the landing gear; on the other hand, it can also reduce the vibration amplitude of the aircraft body, thereby making the posture of the aircraft body more stable, and it is also beneficial to avoid resonance between the landing gear and the fuselage. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0055] Figure 1 A schematic structural diagram of an embodiment of a landing gear provided by the present invention;

[0056] Figure 2 for Figure 1 An exploded view of the parts of the structure shown at the mounting bracket;

[0057] Figure 3 for Figure 2 The schematic diagram of the assembly relationship of the structure shown is after the mounting base is hidden;

[0058] Figure 4 for Figure 1 a top view of the structure shown;

[0059] Figure 5 for Figure 1 a side view of the structure shown;

[0060] Figure 6 for Figure 1 A front view of the structure shown;

[0061] Figure 7 for Figure 1 A partial enlarged view of the structure shown at the second joint;

[0062] Figure 8 for Figure 7 A schematic diagram of the structure of the second joint in FIG.

[0063] Fig. 9 for Figure 1 Another side view of the structure shown.

[0064] Description of Figure Numbers:

[0065] 10. Sled; 11. Front warping section; 12. Rear warping section;

[0066] 20, buffer beam; 201, horizontal and vertical beam section; 202, curved beam section; 21, front beam; 22, rear beam;

[0067] 30. Mounting bracket; 301. Mounting channel; 31. Hoop; 311. First hoop body; 312. Second hoop body; 313. Stop flange; 314. Reinforcement rib; 32. Mounting seat; 321. Make way slot; 33. Anti-slip structure; 331. Anti-slip boss; 332. Mounting boss; 333. Locking piece; 334. Anti-slip gasket;

[0068] 40. Limiting bracket; 41. Third hoop body;

[0069] 51, first connector; 52, second connector; 521, jack; 522, buckle slot;

[0070] 61. Rivet; 62. Nut; 63. Split pin;

[0071] 70. Shock-absorbing pad; 80. Anti-wear pad.

[0072] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0075] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0076] The landing gear is an energy-absorbing structure for aircraft, and its structural stability and mechanical properties play a key role. A skid-type landing gear usually includes two skids and two buffer beams distributed at the front and rear ends of the skids. The middle of the buffer beam is connected to the aircraft body through a mounting bracket, and the ends of the buffer beam are connected to the skid. However, during the take-off or landing phase of the aircraft, the load on the landing gear changes significantly. Therefore, the mounting bracket located on the buffer beam is prone to lateral slip during these processes, which may cause uneven force on the left and right side structures of the landing gear and cause the structure on one side to fail first. Therefore, how to improve the installation stability of the mounting bracket and reduce the probability of lateral slip is a problem that needs to be solved in this field.

[0077] In view of this, the present invention provides a landing gear, which can improve the installation stability of the mounting bracket and reduce the probability of lateral slippage.

[0078] See also Figure 1 In one embodiment of the present invention, the landing gear includes at least two skids 10 and at least two buffer beams 20, wherein the at least two skids 10 are arranged opposite to each other, the buffer beam 20 connects the two skids 10, and the at least two buffer beams 20 are protruded upward and spaced apart along the extension direction of the skid 10, and are used to be installed with the aircraft body. Specifically, the buffer beam 20 protruding upward is generally in an arched structure, so that the elastic deformation of the arched structure itself can be used to absorb the impact energy received by the landing gear.

[0079] Without loss of generality, the aircraft body includes a fuselage and a propeller arranged on the fuselage. The fuselage is installed above the buffer beam and has a crew cabin for a pilot and passengers.

[0080] See also Figure 1 and Figure 4Optionally, the buffer beam 20 has a transverse beam section 201 capable of elastic deformation and two curved beam sections 202, and the curved beam section 202 is connected between the transverse beam section 201 and the skid 10. In this way, in addition to transmitting the load, the buffer beam 20 in this embodiment can also absorb the impact load through the elastic deformation of the transverse beam section 201 and the curved beam section 202, thereby playing an effective energy absorption role, thereby improving the buffering and energy absorption effect of the landing gear.

[0081] See also Figure 1 and Figure 2 Furthermore, the landing gear further includes at least two mounting brackets 30 disposed on the buffer beam 20, and the mounting brackets 30 are used to connect the aircraft body. In this way, the mounting brackets 30 can facilitate the installation of the landing gear and the aircraft body. Of course, in other embodiments, the mounting brackets 30 may not be provided.

[0082] Optionally, at least two buffer beams 20 include a front beam 21 and a rear beam 22, and the transverse and vertical beam sections 201 of the front beam 21 and the rear beam 22 are each provided with at least two mounting brackets 30. Optionally, in this embodiment, two mounting brackets 30 are each provided on the front beam 21 and the rear beam 22, that is, the landing gear is provided with a total of four mounting brackets 30. In this way, on the one hand, the installation stability of the aircraft body can be ensured, and on the other hand, the load transfer path between the landing gear and the aircraft body can be increased, thereby facilitating the improvement of the energy absorption and buffering effect of the landing gear.

[0083] It should be noted that during the design of the landing gear, deformation coordination analysis will be conducted on the landing gear structure that meets the static strength requirements, that is, within the range of the front and rear limits of the center of gravity of the aircraft, the front beam 21 and the rear beam 22 will be subjected to shutdown and overload static strength simulation analysis under gravity and overload loads to ensure that the deformation of the front beam 21 and the rear beam 22 of the landing gear is coordinated and consistent, so that the front and rear deformation and the left and right deformation of the landing gear are consistent, and the rollover moment (such as the rollover moment or the back rollover moment) is smaller than the restoring moment, so as to avoid the overturning and tipping of the aircraft. In other words, the deformation of the front beam 21 and the rear beam 22 in the vertical direction is required to be as consistent as possible, so that the vertical (i.e., vertical direction) displacement of the four mounting brackets 30 (i.e., the fuselage mounting points) thereon is consistent, so that the aircraft can land in a relatively stable posture to avoid the aircraft from tipping and tipping.

[0084] The deformation of the buffer beam 20 in the vertical direction is mainly determined by the deformation of the curved beam section 202, and the curved beam section 202 also plays a major role in buffering and absorbing energy. Therefore, the length of the curved beam section 202 (i.e., its width in the left-right direction of the landing gear) is usually designed to be large. In this embodiment, since the buffer beam 20 as a whole can be elastically deformed, the horizontal beam section 201 can also be elastically deformed to absorb energy. However, if the length of the curved beam section 202 is set to be large, the length of the horizontal beam section 201 will be very small, which is not conducive to the horizontal beam section 201 fully exerting its deformation and energy absorption function.

[0085] Therefore, while the length of the curved beam section 202 is usually designed to be very large in the prior art, the present invention specifically increases the length of the horizontal beam section 201 and increases the distance between the two mounting brackets 30 so that the horizontal beam section 201 can fully exert its deformation energy absorption function. Figure 4 Optionally, two mounting brackets 30 are disposed at opposite ends of a horizontal beam section 201, and the distance between the two mounting brackets 30 is d, and the width of the landing gear in the distribution direction of the mounting brackets 30 is D, 0.3≤d / D≤0.7. It can be understood that the value of the distance d is positively correlated with the length of the horizontal beam section, that is, the longer the horizontal beam section is, the larger the value of the distance d is allowed to be, and vice versa.

[0086] In this embodiment, the structure of the horizontal beam section 201 located between the two mounting brackets 30 can be elastically deformed to absorb energy. In this way, by maximizing the distance between the two mounting brackets 30 located on the same buffer beam 20, on the one hand, the length of the deformable part in the middle of the buffer beam 20 (i.e., the horizontal beam section 201) can be increased, which is beneficial to improving the buffering and energy absorption effect of the landing gear; on the other hand, the vibration amplitude of the aircraft body can be reduced, thereby making the posture of the aircraft body more stable, and it is also beneficial to avoid resonance between the landing gear and the fuselage.

[0087] Of course, the distance d between the two mounting brackets 20 cannot be excessively increased, and it is also necessary to consider that the curved beam section 202 can also play a sufficient role in buffering and absorbing energy. Therefore, preferably, 0.45≤d / D≤0.5, for example, d / D is 0.45, 0.47 or 0.5. In this way, the curved beam section 202 can also have a sufficient length to play its deformation energy absorption role, and it can also ensure that the deformation of the buffer beam 20 in the vertical direction is large enough when the aircraft lands, so that the center of gravity of the aircraft can be lowered and its landing safety can be improved.

[0088] Optionally, the material of the buffer beam 20 is a metal material with excellent elastic properties, such as spring steel, etc., and the material of the skid 10 is a metal material with low density, high specific strength, and high specific stiffness, such as deformed aluminum alloy, etc. Specifically, the buffer beam 20 and the skid 10 are respectively manufactured using spring steel and deformed aluminum alloy, and the two are physically coupled to form a landing gear, wherein the buffer beam 20 made of spring steel has sufficient strength and toughness to meet the impact load, and the skid 10 made of deformed aluminum alloy has sufficient strength and low modulus, so that the material deformation energy absorption utilization rate of the landing gear is significantly increased.

[0089] In this way, on the one hand, the total weight of the landing gear can be reduced as much as possible while meeting the strength requirements, and on the other hand, the overall deformation energy absorption function of the landing gear can be fully utilized so that the landing gear can absorb the impact load well, thereby improving the safety of the aircraft. Of course, in other embodiments, the material of the buffer beam 20 and the skid 10 can also be set to aluminum alloy or spring steel, or other materials.

[0090] Optionally, the buffer beam 20 and the skid 10 are tubular structures, and the cross-sectional shape is circular, elliptical or polygonal. For example, the buffer beam 20 and the skid 10 are both round tubes. In this way, the structure is stable and has good mechanical properties, which is beneficial to the structural stability and buffering energy absorption of the landing gear. Of course, in other embodiments, only the buffer beam 20 or the skid 10 can be configured as a round tube, or the buffer beam 20 and the skid 10 can be configured as an elliptical tube or a square tube, etc. In other embodiments, the buffer beam 20 and the skid 10 can also be configured as a solid rod-shaped structure.

[0091] In order to avoid the problem of easy wear of the skid 10, optionally, the deformed aluminum alloy in this embodiment adopts an ultra-hard deformed aluminum alloy. Of course, other means can also be used to solve this problem at the same time. For example, in one embodiment, the landing gear further includes an anti-wear sheet 80, and the anti-wear sheet 80 is arranged on the lower side of the skid 10. Optionally, the material of the anti-wear sheet 80 is a high-hardness metal, such as stainless steel, titanium alloy or tungsten steel, and can be fixed to the skid 10 by rivets 61. In this way, the anti-wear sheet 80 can prevent the lower side of the skid 10 from directly contacting the ground, and can avoid the problem of easy wear of the skid 10 due to direct contact with the ground, and improve the service life of the skid 10. Of course, in other embodiments, the anti-wear sheet 80 may not be provided.

[0092] Optionally, a plurality of anti-wear sheets 80 are provided on the same skid 10, wherein one anti-wear sheet 80 is provided at the front ground contact point of the skid 10, another anti-wear sheet 80 is provided at the rear ground contact point of the skid 10, and another anti-wear sheet 80 is provided at the middle of the skid 10. The front ground contact point and the rear ground contact point are common knowledge of landing gears in the art, so they are not described in detail here. In this way, the ground contact surface of the skid 10 can be suspended as a whole relative to the ground through the plurality of anti-wear sheets 80, thereby further reducing the risk of wear of the skid 10.

[0093] See also Figures 4 to 6 In one embodiment, at least two buffer beams 20 include a front beam 21, and the end of the front beam 21 has a curved beam section 202, which is bent and extended outward toward the side and rear, and is connected to the front end of the skid 10. That is, the center of the curved beam section 202 is located on the side where the center of the landing gear is located, and the distance between the two curved beam sections 202 gradually increases from the front to the rear. In this way, on the one hand, the curved beam section 202 can also be bent and deformed to absorb the impact load, thereby improving the buffering and energy absorption effect of the landing gear. On the other hand, the curved beam section 202 is bent and extended outward toward the side and rear, which can increase the distance between the two skids 10, thereby making the overall width of the landing gear larger and ensuring that the aircraft has a sufficient anti-rollover angle, and can also reduce air resistance and improve the aerodynamics of the landing gear, thereby reducing the wind resistance of the landing gear during the flight stage. Of course, in other embodiments, the structural form of the front beam 21 can also be other, for example, the end of the front beam 21 can be bent and extended downward, but not extended obliquely toward the side and rear.

[0094] See also Figures 4 to 6 Optionally, the front end of the sled 10 extends to the front and upward with a front warp section 11, which protrudes outward and is connected to the curved beam section 202. In this way, the front warp section 11 and the curved beam section 202 form a smoothly transitioned arc structure, which can continuously transfer the impact energy borne by the buffer beam 20 to the sled 10 on the one hand, so that the sled 10 can also play an energy absorption role; on the other hand, the front warp section 11 itself can also be elastically deformed and absorb the impact energy.

[0095] See also Fig. 9 In this embodiment, the rear beam is arranged close to the center of gravity of the aircraft, and the d / D value on the rear beam is smaller than the d / D value on the front beam. For example, if the d / D value on the rear beam is 0.45, the d / D value on the front beam may be 0.46, 0.47, 0.48, 0.49 or 0.5, etc.

[0096] Specifically, in this embodiment, in the front-rear direction of the landing gear, the center of gravity of the aircraft is closer to the rear beam 22, so when the aircraft lands, the rear beam 22 needs to bear and transfer more load. Therefore, on one hand, by setting the length of the curved beam section 202 of the rear beam 22 to be larger, the rear beam 22 can bear and absorb more impact energy.

[0097] On the other hand, since the curved beam section 202 of the front beam 21 is connected to the front warping section 11 of the sled 10, the vertical displacement of the mounting bracket 30 on the front beam 21 is affected by both the curved beam section 202 and the front warping section 11. That is, under the same load condition, the deformation of the curved beam section 202 and the front warping section 11 of the front beam 21 will increase the vertical displacement of the mounting bracket 30 on the front beam 21. In order to meet the goal of keeping the vertical displacement of the four mounting brackets 30 on the front beam 21 and the rear beam 22 consistent, in particular, by setting the length of the curved beam section 202 of the rear beam 22 to be larger (that is, the d / D value on the rear beam 22 is set to be smaller), the vertical displacement of the mounting bracket 30 on the rear beam 22 can be increased. That is, in this embodiment, considering the particularity of the structural form that the curved beam section 202 of the front beam 21 is connected to the end of the sled 10, the d / D value on the rear beam 22 is set to be smaller than that of the front beam 21.

[0098] Optionally, a rear warping section 12 is extended from the rear end of the sled 10 toward the rear and upward, and the radii of the rear warping section 12, the front warping section 11, and the curved beam section 202 are configured to be the same. In this way, by unifying the curved radii on the buffer beam 20 and the sled 10, the parameter design of the factors to be considered in the design method steps can be simplified, and the design efficiency can be improved and the design cost can be reduced.

[0099] In order to reduce the production cost of the landing gear, in one embodiment, optionally, the bending beam section 202 and the front warping section 11 are formed by a bending machine, and the bending radius of the bending beam section 202 and the front warping section 11 are configured to be the same. That is, the buffer beam 20 and the skid 10 are formed into the bending beam section 202 and the front warping section 11 by a bending machine and a bending mold, respectively. In this way, the bending beam section 202 and the front warping section 11 can share the same set of bending molds, thereby reducing the bending molds required for production and reducing the production cost of the landing gear. Of course, in other embodiments, the bending radius of the bending beam section 202 and the front warping section 11 can be set to be different, or the bending process is not used for forming.

[0100] Optionally, the rear end of the skid 10 extends upward and rearward with a rear warping section 12, and the bending radius of the rear warping section 12 is also configured to be the same as the bending radius of the front warping section 11; the bending radius of the front beam 21 and the rear beam are also configured to be the same. That is, in this embodiment, the rear warping section 12, the front warping section and the curved beam section are formed by a bending machine, and the bending radius is configured to be the same, and the positions that need to be bent in the main structure of the landing gear are all bent and formed by the same bending mold, so that the bending mold can be further saved.

[0101] It is worth mentioning that in the embodiment of the present invention, the main structure of the landing gear is formed by adopting a buffer beam 20 made of spring steel and a skid 10 made of deformed aluminum alloy, and the longitudinal rotation freedom of the mounting bracket 30 on the buffer beam 20 is released. At the same time, a curved beam section 202 and a front warping section 11 are also provided, so that the overall elastic deformation of the landing gear is more sufficient, so as to achieve a multi-stage energy absorption effect of the landing gear.

[0102] Specifically, after the landing gear is subjected to the impact load, part of the energy can be absorbed by the middle part of the buffer beam 20 by releasing its bending freedom and undergoing elastic deformation, and another part of the energy can be absorbed by the bending deformation of the curved beam section 202 of the buffer beam 20, and another part of the energy can be absorbed by the bending deformation of the front warping section 11 of the skid 10, and another part of the energy can be absorbed by the friction between the anti-wear plate 80 and the ground.

[0103] It is understood that there are many ways to achieve physical coupling between the buffer beam 20 and the sled 10, for example, see Figure 1 In one embodiment, the landing gear further comprises a first joint 51, the front beam 21 and the skid 10 are respectively inserted at opposite ends of the first joint 51, and the front beam 21 and / or the skid 10 are fixedly connected to the first joint 51 through a connecting member. Optionally, the connecting member is a rivet 61, and the first joint 51 is a tubular structure, and can be sleeved on the front beam 21 and the skid 10. In this way, the structure is simple and easy to implement. Of course, in other embodiments, the front beam 21 can also be directly welded and fixed to the skid 10, or the connecting member can be a screw.

[0104] In order to improve the installation reliability of the front beam 21, the slide 10 and the first joint 51, optionally, the ratio of the depth of the front beam 21 inserted into the first joint 51 to the diameter of the front beam 21 is in a range of 1 to 2, such as 1.3, 1.5 or 1.7; the ratio of the depth of the slide 10 inserted into the first joint 51 to the diameter of the slide 10 is in a range of 1 to 2, such as 1.3, 1.5 or 1.7.

[0105] See also Figure 5 , Figure 7 and Figure 8, further, at least two buffer beams 20 include a rear beam 22, and the landing gear also includes a second joint 52, the second joint 52 is provided with a plug hole 521 and a buckle groove 522, the end of the rear beam 22 is inserted into the plug hole 521 and fixed by bolts, and the buckle groove 522 is buckled on the upper side of the skid 10 and fixed by rivets 61. Optionally, the second joint 52 is a roughly T-shaped structure, that is, the extension direction of the plug hole 521 and the extension direction of the buckle groove 522 are arranged to intersect. In this way, the structure is simple and easy to implement. Of course, in other embodiments, the rear beam 22 can also be directly welded and fixed on the skid 10.

[0106] It is worth mentioning that the landing gear of the present invention uses different types of rivets 61 according to different forces. High-strength rivets are used at connection positions with large forces, while ordinary-strength rivets, such as ordinary stainless steel rivets, are used at connection positions with small forces. Specifically, the rivets used in the first joint 51 and the second joint 52 are high-strength rivets, while the rivets used in the anti-wear sheet 80 are ordinary-strength rivets. In this way, the production cost of the landing gear can be reduced while satisfying the rivet connection strength. Of course, in other embodiments, the rivets on the landing gear can also be of the same type and specification.

[0107] It is understood that the mounting bracket 30 has various structural forms, for example, see Figure 2 and Figure 3 In one embodiment, the mounting bracket 30 includes a clamp 31, and the clamp 31 includes a first clamp body 311 and a second clamp body 312 connected to each other. The first clamp body 311 and the second clamp body 312 clamp the buffer beam 20 together, and enable the clamp 31 to rotate around an axis extending in the left-right direction. In this way, by releasing the rotational freedom of the clamp 31 in the longitudinal direction, that is, enabling the clamp 31 to rotate around the transverse axis, when the landing gear is subjected to an impact load, the buffer beam 20 can generate sufficient bending deformation to absorb energy, thereby improving the buffering energy absorption effect of the landing gear. That is, since the clamp 31 can rotate around the axis extending in the left-right direction, the rotation constraint along the heading caused by the deformation of the buffer beam 20 can be released, so that the horizontal beam section 201 of the buffer beam 20 can be deformed together with the curved beam section 202, thereby increasing the buffering capacity of the landing gear. Of course, in other embodiments, the mounting bracket 30 may also be of other structural forms. For example, the mounting bracket 30 includes an arc-shaped plate and a straight plate. The arc-shaped plate covers the upper side of the buffer beam 20 and is fixed by bolts or rivets 61. The straight plate is arranged on the upper side of the arc-shaped plate and is fixed to the aircraft body by bolts or rivets 61.

[0108] See also Figure 2Furthermore, the mounting bracket 30 includes a mounting seat 32 and a stop structure 33, the mounting seat 32 is connected to the aircraft body, and the stop structure 33 connects the mounting seat 32 and the buffer beam 20 to limit the mounting seat 32 from being separated from the buffer beam 20 in the up and down direction. In this way, the anti-falling design is realized by the stop structure 33, which can effectively prevent the mounting seat 32 from being separated from the buffer beam 20 in the up and down direction during the flight phase of the aircraft or when the landing gear is subjected to a downward load, thereby preventing the landing gear from being separated from the aircraft body. Of course, in other embodiments, the stop structure 33 may not be provided, and the mounting seat 32 may be directly welded and fixed to the buffer beam 20.

[0109] Optionally, the side wall of the mounting seat 32 is provided with a yielding groove 321 with a notch facing downward, and the anti-slip structure 33 includes an anti-slip boss 331, a mounting boss 332 and a locking member 333. The anti-slip boss 331 extends outward from the notch edge of the yielding groove 321, and the mounting boss 332 is installed on the buffer beam 20. The yielding groove 321 can be sleeved on the mounting boss 332 from top to bottom, and the locking member 333 is detachably installed on the mounting boss 332 and abuts against the upper side of the anti-slip boss 331.

[0110] Optionally, the first hoop body 311 is disposed above the second hoop body 312 and is used to connect to the aircraft body, and the mounting boss 332 is fixedly disposed on the first hoop body 311 .

[0111] Specifically, see Figure 2 and Figure 3 When the locking cam 331 is in the unlocking state, the locking cam 332 is in the unlocking state, and the locking cam 332 is in the unlocking state.

[0112] See also Figure 2 Optionally, the mounting boss 332 is a stud, and the locking member 333 includes a nut 62 and an anti-slip washer 334. The nut 62 is locked on the mounting boss 332, and the anti-slip washer 334 is clamped on the mounting seat 32. The anti-slip washer 334 abuts against the upper side of the anti-slip boss 331. In this way, the structure is simple, and the mounting seat 32 and the first hoop body 311 are easy to install, disassemble and maintain.

[0113] It should be noted that the landing load of the landing gear is transmitted by extrusion, that is, the landing gear's own gravity and the downward inertial load on the landing gear caused by flight will be transmitted to the aircraft body through the anti-slip pad 334 on the mounting boss 332.

[0114] Of course, in other embodiments, the mounting boss 332 may not be provided with an external thread, and the locking member 333 may be a sheet-like structure and can be sleeved on the mounting boss 332 . When the locking member 333 abuts against the anti-slip boss 331 , it is welded and fixed on the mounting boss 332 .

[0115] Optionally, the nut 62 in the locking member 333 is a slotted nut, which is fixed circumferentially relative to the stud by a cotter pin 63. In this way, the problem of the nut 62 loosening or even coming off can be avoided, thereby improving the installation reliability of the mounting seat 32.

[0116] Optionally, the connection gap between the nut 62 and the stud is filled with protective glue (not shown in the drawings). Optionally, the protective glue is a waterproof glue, such as epoxy resin waterproof sealant, anaerobic glue or pre-coated thread locker. In this way, the protective glue can not only prevent the nut 62 from loosening, but also effectively prevent the corrosion and failure of the thread structure on the nut 62 and the stud. Of course, in other embodiments, the protective glue may not be provided.

[0117] Optionally, the stop flange 313 is provided on the first hoop body 311 and / or the second hoop body 312, for example, see Figure 2 , the stop flange 313 may be provided only on the second hoop body 312 .

[0118] Optionally, the mechanical strength of the first hoop body 311 is greater than that of the second hoop body 312. It should be noted that the mechanical strength of the first hoop body 311 is greater than that of the second hoop body 312, which means that the structural strength of the first hoop body 311 is greater than that of the second hoop body 312, and the strength difference can be achieved by using materials with different strengths or by using different structural parameters (such as material thickness).

[0119] See also Figure 4 Optionally, the first hoop body 311 and the second hoop body 312 are provided with reinforcing ribs 314, and the reinforcing ribs 314 surround the outer circumference of the clamp 31 along the front-rear direction of the landing gear. The number of reinforcing ribs 314 on the first hoop body 311 is greater than the number of reinforcing ribs 314 on the second hoop body 312, and the multiple reinforcing ribs 314 on the first hoop body 311 are arranged along the left-right direction of the landing gear.

[0120] Specifically, in this embodiment, the first hoop body 311 is provided with three reinforcing ribs 314 and the second hoop body 312 is provided with one reinforcing rib 314. It can be understood that since the first hoop body 311 is mainly subjected to the impact load when the aircraft lands, it needs to withstand a large shear force and has a high strength requirement, so it is made of ultra-high strength steel and has multiple reinforcing ribs 314; while the second hoop body 312 is only subjected to the gravity of the landing gear itself after the aircraft takes off, and the force is relatively small, so it is made of ordinary structural steel and has only one reinforcing rib 314. In this way, this embodiment can reduce weight and cost to the greatest extent while meeting the strength and impact resistance of the landing gear.

[0121] Of course, in other embodiments, the number of reinforcing ribs 314 of the first hoop body 311 and the second hoop body 312 may be the same, or the mechanical strength of the first hoop body 311 may be less than or equal to that of the second hoop body 312 .

[0122] Please also read Figure 2 and Figure 3 Furthermore, the landing gear also includes a limit bracket 40, which is arranged on the buffer beam 20 and cooperates with the mounting bracket 30 to limit the lateral displacement of the mounting bracket 30. In this way, since the limit bracket 40 is designed to better maintain its installation position on the buffer beam 20, the lateral displacement of the mounting bracket 30 on the buffer beam 20 can be prevented by the limit bracket 40, so that the relative position of the mounting bracket 30 on the buffer beam 20 remains unchanged, so that the relative position of the aircraft body and the landing gear in the lateral direction remains unchanged, and then in different stages such as the take-off stage or the landing stage, the landing gear can maintain a state of balanced force on the left and right side structures, and avoid the problem of the structure of one side of the landing gear failing first. In this way, the installation stability of the mounting bracket 30 can be improved, and the probability of its lateral slip can be reduced, thereby improving the safety of the aircraft.

[0123] It should be noted that, in the embodiment of the present invention, the lateral direction refers to the left-right direction of the aircraft, the longitudinal direction refers to the front-back direction of the aircraft, and the vertical direction refers to the up-down (vertical) direction of the aircraft. Without loss of generality, the aircraft body and the landing gear are distributed vertically, and the landing gear is arranged on the lower side of the aircraft body, the skid 10 of the landing gear extends approximately in the longitudinal direction, and the middle part of the buffer beam 20 extends approximately in the lateral direction.

[0124] It can be understood that there are many ways for the limiting bracket 40 to achieve the limiting cooperation with the mounting bracket 30, for example, see Figure 4In one embodiment, two mounting brackets 30 are arranged at intervals on the same buffer beam 20, and two limiting brackets 40 are correspondingly arranged and located at the intervals between the two mounting brackets 30, and the limiting bracket 40 abuts against the end face of the mounting bracket 30 close to the other mounting bracket 30. That is, the limiting bracket 40 on the left abuts against the right end face of the mounting bracket 30 on the left, and the limiting bracket 40 on the right abuts against the left end face of the mounting bracket 30 on the right. When the mounting bracket 30 has a tendency to slide to the left, the limiting bracket 40 on the right can prevent the sliding from occurring; when the mounting bracket 30 has a tendency to slide to the right, the limiting bracket 40 on the left can prevent the sliding from occurring.

[0125] In this way, on the one hand, the installation of the landing gear is achieved through two spaced-apart mounting brackets 30, which is conducive to improving the installation reliability of the landing gear and increasing the load transfer path so that the landing gear can better absorb energy and play a better shock-absorbing and buffering role. On the other hand, only two limit brackets 40 are needed to limit the sliding of the mounting bracket 30 to the left or to the right. The structure is simple and easy to implement, and the manufacturing cost of the landing gear can be reduced. Of course, in other embodiments, four limit brackets 40 can be provided, and two opposite end faces of a mounting bracket 30 are each abutted against a limit bracket 40.

[0126] In other embodiments, only one limiting bracket 40 may be provided, and the limiting bracket 40 is mounted on the mounting bracket 30 by means of bolts, rivets 61 or snap-fit ​​structures, so as to achieve the limiting cooperation between the limiting bracket 40 and the mounting bracket 30. In this case, one limiting bracket 40 can simultaneously restrict the sliding tendency of the mounting bracket 30 to the left and to the right.

[0127] See also Figure 2 The limit bracket 40 is configured as a clamp and is arranged around the peripheral side of the buffer beam 20. Specifically, the clamp includes two third hoop bodies 41, which are locked and fixed by bolts and nuts 62, and are together arranged around the peripheral side of the buffer beam 20. Specifically, the limit bracket 40 simply holds the buffer beam 20, so a clamp type with a larger friction coefficient can be selected to make it difficult to be disturbed by external forces and displaced laterally after holding the buffer beam 20, so as to ensure that the limit bracket 40 can limit the lateral displacement of the mounting bracket 30. In this way, the limit bracket 40 has a simple structure and is easy to install and disassemble, and the limit bracket 40 is installed and fixed on the buffer beam 20 by holding, so there is no need to open holes in the buffer beam 20, so that the good structural strength and mechanical properties of the buffer beam 20 can be maintained.

[0128] Optionally, the nuts 62 used in the two third hoop bodies 41 are slotted nuts, and are fixed circumferentially relative to the bolts using cotter pins 63 to avoid the nut 62 from loosening or even coming off, thereby improving the installation reliability of the clamp.

[0129] Of course, in other embodiments, the limiting bracket 40 may also be an L-shaped bracket, one side wall of the L-shaped bracket is directly locked on the buffer beam 20 by bolts, and the other side wall abuts against the end surface of the mounting bracket 30 .

[0130] It can be understood that there are many ways to install the mounting bracket 30 and the buffer beam 20. For example, see Figure 2 and Figure 3 In one embodiment, the mounting bracket 30 has a mounting channel 301, the buffer beam 20 is disposed in the mounting channel 301, and the landing gear further includes a shock-absorbing pad 70 capable of elastic deformation, and the shock-absorbing pad 70 is disposed between the side wall surface of the mounting channel 301 and the peripheral side surface of the buffer beam 20. That is, the mounting bracket 30 is indirectly mounted on the buffer beam 20 through the shock-absorbing pad 70. In this way, the shock-absorbing pad 70 can play multiple roles. The first is the buffering and energy absorption role. The second is to increase the friction between the buffer beam 20 and the mounting bracket 30 to reduce the risk of lateral displacement of the mounting bracket 30. The third is to prevent the buffer beam 20 from being worn due to direct rigid contact with the mounting bracket 30 when the landing gear is deformed and rotated under load, resulting in relative rotation between the buffer beam 20 and the mounting bracket 30. This protects the buffer beam 20 from wear and improves the integrity of the main structure of the landing gear. Fourth, when manufacturing tolerances and assembly tolerances cause assembly gaps between multiple buffer beams 20 and the aircraft body, the assembly gap can be tolerated to facilitate assembly and molding of the landing gear and the aircraft body.

[0131] Optionally, the shock-absorbing pad 70 is made of rubber or silicone, and its buffering performance and supporting stiffness can be adjusted and optimized by adjusting the thickness and material selection of the shock-absorbing pad 70 .

[0132] Of course, in other embodiments, the shock-absorbing pad 70 may not be provided, and the mounting bracket 30 may be directly sleeved on the buffer beam 20 .

[0133] See also Figure 2 The end surface of the installation channel 301 extends inwardly with a stop flange 313, and the inner end surface of the stop flange 313 abuts against the end surface of the shock absorbing pad 70. That is, the stop flange 313 is provided at the channel opening of the installation channel 301, and the shock absorbing pad 70 is provided in the installation channel 301 and abutted by the stop flange 313, thereby preventing the shock absorbing pad 70 from falling out of the installation channel 301. Of course, in other embodiments, the stop flange 313 may not be provided.

[0134] Optionally, a limiting protrusion is provided outside the installation channel 301, and the limiting protrusion abuts against the limiting bracket 40. Figure 2 , further optionally, the limiting protrusion and the stop flange 313 are configured as the same structure, that is, the outer end surface of the stop flange 313 abuts against the limiting bracket 40. In this way, this embodiment is conducive to simplifying the structure of the landing gear and reducing its manufacturing cost by reusing the stop flange 313 as a structure for the limiting bracket 40 to abut. Of course, in other embodiments, other structures can also be used to abut against the limiting bracket 40, that is, the limiting protrusion and the stop flange 313 are different structures.

[0135] It is understood that the mounting bracket 30 has various structural forms, for example, see Figure 2 In one embodiment, the mounting bracket 30 includes a clamp 31, and the clamp 31 includes a first clamp body 311 and a second clamp body 312 connected to each other. The first clamp body 311 and the second clamp body 312 clamp the buffer beam 20 together, and enable the clamp 31 to rotate around an axis extending in the left-right direction. In this way, by releasing the rotational freedom of the clamp 31 in the longitudinal direction, that is, enabling the clamp 31 to rotate around the transverse axis, when the landing gear is subjected to an impact load, the buffer beam 20 can generate sufficient bending deformation to absorb energy, thereby improving the buffering energy absorption effect of the landing gear. Of course, in other embodiments, the mounting bracket 30 can also be other structural forms, for example, the mounting bracket 30 includes an arc plate and a straight plate, the arc plate covers the upper side of the buffer beam 20 and is fixed by bolts or rivets 61, and the straight plate is arranged on the upper side of the arc plate and is fixed to the aircraft body by bolts or rivets 61.

[0136] Without loss of generality, during the installation of the aircraft body and the landing gear, the first hoop body 311 is usually installed on the lower side of the aircraft body in advance. Then, when the aircraft body is suspended in the air, the landing gear is lifted to be close to the lower side of the aircraft body, and the first hoop body 311 is aligned with its installation position area on the buffer beam 20. Then, the second hoop body 312 is buckled on the lower side of the buffer beam 20 and aligned with the first hoop body 311. Finally, the second hoop body 312 is locked to the first hoop body 311 using a pair of bolts and nuts 62, thereby realizing the installation and fixing operation of the landing gear on the aircraft body.

[0137] It can be understood that how to prompt the first hoop body 311 to quickly and accurately align its installation position area on the buffer beam 20 can be achieved in a variety of ways, for example, a positioning line segment or a positioning wire frame can be engraved on the buffer beam 20, or during the alignment process of the first hoop body 311, the area can be located on the buffer beam 20 by irradiating a laser beam.

[0138] It is worth mentioning that in the embodiment where two limiting brackets 40 are provided and respectively abut against the inner end faces of the two mounting brackets 30 (i.e., the end faces of the two mounting brackets 30 facing each other), before the hoop 31 is assembled, since the limiting bracket 40 has been accurately installed on the buffer beam 20 in advance, the limiting bracket 40 can play a positioning role. Specifically, in the process of assembling the main structure of the landing gear (including the skid 10 and the buffer beam 20) using a jig, the limiting bracket 40 can be further accurately installed on the buffer beam 20 by means of laser positioning and the like. When the subsequent aircraft body and the first hoop body 311 thereon fall on the buffer beam 20, the first hoop body 311 is placed on the edge of the limiting bracket 40, so that the first hoop body 311 can be quickly and accurately aligned with its installation position area on the buffer beam 20.

[0139] It can be seen that the embodiment of the present invention plays the role of installing and positioning the clamp 31 through the limiting bracket 40. On the one hand, compared with the method of engraving the positioning line segment or the positioning wire frame on the buffer beam 20, it can save the production process of engraving the positioning line segment or the positioning wire frame on the buffer beam 20, and it is easier to identify the positioning area with the naked eye. On the other hand, compared with the method of irradiating the buffer beam 20 with a laser beam during the alignment process of the first clamp body 311, the laser alignment operation can be saved at this stage, thereby simplifying the assembly operation of the landing gear and the aircraft body, and overcoming the problem of poor positioning accuracy caused by changes in the positioning reference.

[0140] It is worth mentioning that the clamp 31, limit bracket 40 and anti-wear plate 80 of the landing gear of the present invention are all replaceable units to achieve the design purpose of LRU (Line Replaceable Unit), thereby making the maintenance of the landing gear more convenient and the maintenance cycle shorter.

[0141] The present invention also provides an aircraft, which includes an aircraft body and a landing gear. The specific structure of the landing gear refers to the above embodiment. Since the present aircraft adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the landing gear is arranged on the lower side of the aircraft body.

[0142] Optionally, the aircraft may be an eVTOL (Electric Vertical Take off and Landing) electric vertical take-off and landing aircraft, or a helicopter, etc., and this application does not make any specific limitations on this.

[0143] The present invention further provides a landing gear design method, which includes steps S110 to S140, which are specifically as follows:

[0144] Step S110: constructing an initial wireframe model of the landing gear.

[0145] First, formulate an initial plan for the overall layout of the landing gear. You can first determine the external constraints of the landing gear design, determine the position of the landing gear skid according to the aircraft take-off, landing and parking requirements, and determine the height position of the buffer beam and its relative position on the skid according to the position area on the aircraft body for connection with the landing gear.

[0146] In this embodiment, the initial wireframe model of the landing gear includes two skids and two buffer beams, wherein the buffer beam is connected between the two skids and is protruding upward, the two buffer beams are distributed along the front-to-back direction, and the two skids are distributed along the left-to-right direction; the buffer beam includes a transverse beam section and a curved beam section, and the curved beam section is connected between the transverse beam section and the skids.

[0147] Without loss of generality, the overall layout parameters of the landing gear are mainly:

[0148] (a) Parking angle φ: the angle between the longitudinal axis of the aircraft and the parking surface when the aircraft is parked;

[0149] (b) Longitudinal span b: the longitudinal length of the line formed by all the ground contact points of the skid;

[0150] (c) Lateral span B: the lateral distance between the left and right skids;

[0151] (d) Minimum distance of structure from the ground h0: the distance from the ground at the lowest point of the aircraft fuselage;

[0152] (e) Height of centre of gravity above the ground, h: the distance above the ground of the centre of gravity of the aircraft when the landing gear is in contact with the ground and not compressed;

[0153] (f) Rear cowl angle β: the angle between the plane formed by the center of gravity of the aircraft and the rear contact points of the left and right skids and the vertical plane of the center of gravity when the aircraft is parked;

[0154] (g) Front cowl angle γ: the angle between the plane formed by the center of gravity of the aircraft and the front contact points of the left and right skids and the vertical direction of the center of gravity when the aircraft is parked;

[0155] (h) Side cover angle ε: when the machine is stopped, the angle between the plane formed by the center of gravity and the front and rear ground contact points of the skid and the vertical to the center of gravity;

[0156] (i) Autorotation landing angle θ: The angle between the plane through the rear contact point of the skid and the tail strut and the parking ground when the landing gear is not compressed.

[0157] Among them, in order to make the aircraft's fuselage posture basically horizontal when flying forward, the aircraft's propeller plane is often not parallel to the fuselage horizontal line, but tilted forward at a certain angle γ. However, when the aircraft lands on the ground, the forward tilt angle of the propeller shaft generates a forward pulling force, causing the aircraft to have a tendency to slide forward. To avoid this phenomenon, the fuselage is tilted back at a certain angle when parking to reduce or even offset the forward pulling force generated by the propeller. The angle at which the fuselage tilts back when parking is the parking angle. The parking angle φ has a value range of 0≤φ≤γ. Too large a backward tilt angle will cause the horizontal component of the propeller pulling force to be directed backward, causing the aircraft to slide backward. For example, the parking angle φ can be 2°.

[0158] The greater the minimum distance h0 of the structure from the ground, the greater the distance between the lowest point of the fuselage and the ground when the aircraft contacts the ground, which can effectively ensure that the fuselage of the aircraft does not contact or even collide with protrusions on the ground. However, the minimum distance h0 of the structure from the ground also affects the values ​​of other overall layout parameters (such as the rear shroud angle β, the side shroud angle ε, and the longitudinal span b). Therefore, h0 should not be too large, otherwise it will lead to the adverse effects of excessive height of the landing gear and excessive weight. For example, the value range of h0 can be 150mm<h0<500mm.

[0159] The position of the center of gravity of the aircraft has a profound impact on the overall layout of the landing gear. The center of gravity position is marked on the fuselage. The height of the center of gravity above the ground h = the minimum distance of the structure from the ground h0 + the height of the center of gravity from the lowest point of the fuselage h1.

[0160] See also Fig. 9 According to the design specifications of the skid landing gear, the range of the front shroud angle γ and the rear shroud angle β is 30° to 40°. Therefore, two lines L1 and L2 can be drawn through the center of gravity of the aircraft, which are 30° and 40° from the vertical direction, and then a circle with a diameter of 150mm can be drawn through the point where the tail support touches the ground when the aircraft flips backward (such as Figure 8 (As shown by the thin dotted circle above the rear side of the landing gear), two tangent lines are drawn through the intersection of L1 and L2 with the ground and this circle, and the range of the autorotation landing angle θ can be obtained. Due to the weight control requirements of the aircraft, it is hoped that the skid is as short as possible, so the initial value of the autorotation landing angle θ can be set to 30° for layout.

[0161] See also Figure 6 Another constraint on the landing gear design is the value of the side cover angle ε. To avoid the aircraft from rolling over, the side cover angle ε of the aircraft cannot be too small. Take the left rollover as an example. At the moment of rollover, the right skid just leaves the ground and only the left skid touches the ground. At this time, the force on the aircraft is as follows: the gravity G of the aircraft, the support force N, friction force f, and inertia force P provided by the ground at the left skid. The inertia force P and the friction force f constitute the rollover moment, and the gravity G and the support force N constitute the restoring moment. In order to prevent the aircraft from rolling over, it is necessary to ensure that the restoring moment is greater than the rollover moment, that is, the following equations ① and ② need to be satisfied:

[0162] Gx>fh formula ①

[0163]

[0164] Among them, x refers to the distance from the center of gravity of the aircraft to the point where the main wheels touch the ground, and this distance affects the restoring moment of the aircraft. The size of the side cover angle ε represents the level of the aircraft's anti-rollover capability. From the above formula, it can be seen that the lower the center of gravity of the aircraft, the larger the lateral spacing between the left and right skids, the larger the side cover angle ε, and the better the anti-rollover capability. The coordinates of the center of gravity of the aircraft are given by the aircraft as a whole, and major changes cannot be made during the design of the landing gear; and due to the drag and weight restrictions of the aircraft fuselage, the lateral span B between the left and right skids should not be too large, and the smallest possible lateral span should be selected within the range of anti-rollover requirements. Normally, the side cover angle ε is 30° to 40°, from which the value range of the lateral span B can be obtained, and usually to ensure weight and wind resistance, the lateral span B can be taken as 30° for calculation.

[0165] After determining the values ​​of the front hood angle γ and the rear hood angle β, the longitudinal span b can be determined.

[0166] After the initial overall layout plan of the landing gear is drawn up, the position of the fuselage mounting point on the buffer beam needs to be drawn up. Without loss of generality, two fuselage mounting points are usually arranged at intervals on the same buffer beam, and these two fuselage mounting points are usually arranged at opposite ends of the horizontal and vertical beam section of the buffer beam. That is, in this embodiment, two fuselage mounting points are arranged at opposite ends of the horizontal and vertical beam section, and the distance between the two fuselage mounting points is d. It can be understood that the value of the distance d is positively correlated with the length of the horizontal and vertical beam section, that is, the longer the horizontal and vertical beam section is, the larger the value of the distance d is allowed to be, and vice versa.

[0167] It should be noted that the aircraft body usually includes a fuselage and a propeller arranged on the fuselage. The fuselage is installed above the buffer beam and has a crew cabin for the pilot and passengers. The fuselage mounting point in this embodiment refers to the installation position of the fuselage on the buffer beam, and the landing gear mounting bracket mentioned above is installed at the location of the fuselage mounting point.

[0168] Step S120: constructing a primary simulation model of the landing gear according to the initial wireframe model, and performing mechanical analysis and modal analysis.

[0169] The mechanical analysis includes static analysis and dynamic simulation analysis to respectively verify the static performance and dynamic performance of the primary simulation model of the landing gear, wherein the static analysis can be performed before the dynamic simulation analysis.

[0170] It is worth mentioning that when constructing the primary simulation model of the landing gear, the connection between the skid and the buffer beam can be simulated as a common node connection, which can significantly reduce the amount of calculation of computer simulation analysis, quickly clarify the design optimization ideas of the landing gear, and thus shorten the design cycle of the landing gear.

[0171] It is understandable that when a skid-type landing gear is subjected to an impact dynamic load from an aircraft, the skid and the buffer beam work together to absorb the landing energy. Considering the energy absorption, it is hoped that the landing gear deformation is as large as possible. However, due to the limitation of the elastic modulus of the material, when the material deformation exceeds a certain limit, irreversible plastic deformation will occur. Therefore, it is hoped that the deformation of the material is within the elastic deformation range. In this way, it is necessary to find a boundary condition for the deformation of the landing gear so that the deformation of the material is maximized without plastic deformation. This goal can be achieved by iterative optimization based on the results of mechanical analysis.

[0172] Among them, the transverse and vertical beam sections and the curved beam sections of the buffer beam can both be elastically deformed to play an energy absorption role, and the elastic deformation and energy absorption effect of the transverse and vertical beam sections and the curved beam sections are closely related to the positions of the fuselage installation points on them. That is, the arrangement of the fuselage installation points determines the energy absorption distribution ratio and elastic deformation of the transverse and vertical beam sections and the curved beam sections of the buffer beam, and in order to make the energy absorption responsibility of one of the transverse and vertical beam sections and the curved beam section significantly greater than that of the other, it is not advisable to set the length of the transverse and vertical beam sections too large or too small.

[0173] Secondly, if the curved beam section of the buffer beam accounts for a large proportion, that is, when the bending radius of the curved beam section is large, the length of the horizontal and vertical beam section in the middle of the buffer beam will be correspondingly shorter, and the distance d between the two fuselage mounting points will be shorter, which will increase the resonance risk of the fuselage. Therefore, in this embodiment, modal analysis is also added to avoid the vibration frequency of the landing gear and the vibration frequency of the fuselage being too close, so as to ensure that the fuselage and the landing gear will not resonate at the same frequency when the aircraft lands. That is, the value of the distance d is reasonably determined by the results of the modal analysis to reduce the risk of resonance of the fuselage.

[0174] If the results of the mechanical analysis and modal analysis of the primary simulation model meet the requirements, step S121 is executed: determining that the primary simulation model is qualified.

[0175] If not, that is, if any one of the drop simulation analysis result and the static performance of the secondary simulation model of the landing gear does not meet the requirements, step S122 is executed: optimizing and iterating the primary simulation model until the analysis result meets the requirements.

[0176] Step S130: determining the value of the distance d according to a qualified primary simulation model.

[0177] After analysis, it is found that the ratio of the spacing d to the width D of the landing gear is more reasonable at 30% to 70%, and more preferably at 45% to 50%. That is, 0.3≤d / D≤0.7, for example, d / D is 0.45 or 0.5.

[0178] In this way, by maximizing the spacing d, that is, maximizing the distance between the two mounting brackets 30 located on the same buffer beam 20, on the one hand, the length of the deformable portion in the middle of the buffer beam 20 (that is, the horizontal and vertical beam sections) can be increased, which is beneficial to improving the buffering and energy absorption effect of the landing gear; on the other hand, it can also reduce the vibration amplitude of the aircraft body, thereby making the posture of the aircraft body more stable, and it is also beneficial to avoid resonance between the landing gear and the fuselage.

[0179] In the second embodiment of the design method, based on the solution of the first embodiment of the design method, the landing gear design method further includes step S140 and step S150:

[0180] Step S140: constructing a secondary simulation model of the landing gear according to the primary simulation model and the connection structure connecting the skid and the buffer beam; wherein the bending radius of the bending beam section of the secondary simulation model is R G ;

[0181] Step S150: Performing a drop simulation analysis on the secondary simulation model to determine the minimum bending radius R of the curved beam segment. Gm ; Wherein, the bending radius R G Greater than the minimum bending radius R Gm .

[0182] As mentioned above, the horizontal and vertical beam sections and the curved beam sections of the buffer beam can elastically deform to absorb energy. On the basis of the spacing d (equivalent to the length of the horizontal and vertical beam sections), the bending radius R of the curved beam section needs to be further determined. G .

[0183] The bending radius R G As long as the value is greater than the minimum bending radius R Gm , it can ensure that the curved beam section can still maintain structural effectiveness when the landing gear is subjected to maximum load, and on this basis, it can play its role of elastic deformation and energy absorption.

[0184] That is, the minimum bending radius R Gm , which means that under the premise that other structural parameters are the same, when the bending radius of the curved beam segment is less than or equal to the minimum bending radius R Gm When the landing gear is subjected to the impact of the impact, it is unable to maintain the effectiveness of the structure during the drop simulation analysis phase, for example, structural failure occurs at the bending beam section.

[0185] In addition to the above-mentioned drop shock simulation analysis steps, a deformation coordination analysis can also be performed. Specifically, a deformation coordination analysis is performed on the landing gear structure that meets the static strength requirements, that is, within the range of the front and rear limits of the center of gravity of the aircraft, the front and rear beams are subjected to shutdown and overload static strength simulation analysis under gravity and overload, and the vertical deformation of the landing gear at the four fuselage mounting points remains consistent. If the parameter design of the front and rear beams does not meet the load-deformation coordination constraint conditions, the design parameters (including geometric parameters) of the landing gear structure can be adjusted and the above-mentioned deformation coordination analysis can be repeated until the landing gear structure meets the goal of coordinated deformation of the front and rear beams.

[0186] In this way, it can be ensured that the deformation of the front beam and the rear beam of the landing gear is coordinated while meeting the static strength requirements, so that the front and rear deformations and the left and right deformations of the landing gear are consistent, and the rollover moment (such as the side rollover moment or the rear rollover moment) is smaller than the restoring moment, thereby avoiding the overturning of the aircraft.

[0187] In the third embodiment of the design method, the rear end of the sled has a rear warping section, and based on the solution of the second embodiment of the design method, the sled of the secondary simulation model is provided with a rear warping section at the rear end, and the bending radius of the rear warping section is R R ;

[0188] The step of performing a drop shock simulation analysis on the secondary simulation model is also used to determine the minimum unyielding radius R of the rear warping section of the landing gear when the landing gear is flipped over at a later angle. Rm ; Wherein, the bending radius R R Greater than the minimum unyielding radius R Rm .

[0189] The bending radius R R As long as the value is greater than the minimum unyielding radius R Rm , it can ensure that when the rear end of the skid is subjected to the maximum load, for example, when the landing gear is turned over at a later angle for landing, the structural effectiveness can still be maintained, and on this basis, its elastic deformation energy absorption function can be exerted.

[0190] That is, the minimum unyielding radius R Rm , which means that under the premise that other structural parameters are the same, when the bending radius of the post-warping section is less than or equal to the minimum unyielding radius R Rm When the landing gear is subjected to the impact of the impact, it is unable to maintain the effectiveness of the structure during the drop simulation analysis phase, for example, structural failure occurs at the rear warping section.

[0191] In this embodiment, considering that the rear end of the skid should touch down at a point where the aircraft's backflip angle is smaller than the rear cover angle, in order to prevent the aircraft from backflipping when landing, and in order to prevent the tail support of the aircraft from being damaged when the aircraft lands at the maximum backflip angle, the rear warping section (i.e., the rearward bending section of the skid's rear end) coincides with the anti-backflip angle line, and the bending radius R of the rear warping section is R It must be larger than the minimum unyielding radius R obtained by the drop shock simulation when the aircraft is flipped over and landing. Rm .

[0192] In the fourth embodiment of the design method, the front end of the slide has a front warping section, and based on the solution of the third embodiment of the design method, the slide of the secondary simulation model is provided with a front warping section at the front end, and the bending radius of the front warping section is R F ;

[0193] The step of performing drop shock simulation analysis on the secondary simulation model is also used to determine the minimum bending radius R of the front warping section. Fm ; Wherein, the bending radius R F Greater than the minimum bending radius R Fm .

[0194] The bending radius R F As long as the value is greater than the minimum bending radius R Fm , it can ensure that when the front end of the skid is subjected to the maximum load, for example, when the landing gear lands at a forward flip angle, the structural effectiveness can still be maintained, and on this basis, its elastic deformation energy absorption function can be exerted.

[0195] That is, the minimum bending radius R Fm , which means that under the premise that other structural parameters are the same, the bending radius of the current warping segment is less than or equal to the minimum bending radius R Fm When the landing gear is subjected to the impact of the impact, it is unable to maintain the effectiveness of the structure during the drop simulation analysis phase, for example, structural failure occurs at the front warping section.

[0196] In this embodiment, the bending radius of the front warping section of the skid and the bending beam section of the buffer beam are determined by the drop shock simulation method. The landing gear should first meet the overall layout requirements, and then the minimum bending radius (including R Gm and R Fm ).

[0197] On this basis, in order to facilitate the docking of the front warping section of the sled and the curved beam section of the front beam, a first joint is set between the two, and a straight pipe section is provided corresponding to the first joint. That is, a straight pipe section is extended from the front end of the front warping section and the rear end of the curved beam section, and these two straight pipe sections are inserted and fixed in the first joint. Therefore, in the process of confirming the bending radius of the front warping section and the curved beam section of the front beam, the length of the straight pipe sections at the ends of the two also needs to be considered synchronously to ensure that the connection between the sled and the front beam has enough straight distance to install the first joint.

[0198] It can be understood that the structural form of the slide and the buffer beam can be basically determined through the above steps. For example, taking the slide as an example, the longitudinal span b of the slide can be determined through the overall layout step, and then the bending radius of the front warping section of the slide can be determined through the step of performing a drop shock simulation analysis on the secondary simulation model. The front end boundary of the front warping section can be determined through the height of the front beam from the ground and the joint length of the first joint. In this way, the starting position, end position and bending radius of the front warping section can be determined one by one.

[0199] The structure corresponding to the bending radius in the above-mentioned design method embodiment can be realized by a bending process, or by a stamping, die-casting or other process.

[0200] Of course, in the embodiment where the structures of the buffer beam or the slide corresponding to the above-mentioned multiple bending radii are all implemented by the bending process, optionally, the bending radius is R G , bending radius R R and bending radius R F The value configuration is the same.

[0201] That is, specifically and optionally, in the fifth embodiment of the design method, based on the solution of the fourth embodiment of the design method, the bending radius R G , bending radius R R and bending radius R F The value of is the same and is greater than the minimum bending radius R Gm , minimum unyielding radius R Rm and minimum bending radius R Fm That is, the minimum bending radius R calculated in the above steps is Gm , minimum unyielding radius R Rm and minimum bending radius R Fm Finally, any one of the three needs to be smaller than the value of the bending radius of the buffer beam and the slider, so that the bending structures on the buffer beam and the slider can meet the performance requirements.

[0202] In this way, by unifying the bending radius on the buffer beam and the slide, on the one hand, in embodiments where these bending structures are realized by a bending process, the development cost of the bending mold can be reduced; on the other hand, the parameter design of the factors that need to be considered in the design method steps can be simplified, and the design efficiency can be improved and the design cost can be reduced.

[0203] Furthermore, by making the bending radius of all the bending structures of the skid and the buffer beam consistent, the low-cost design purpose can be further achieved. The above-mentioned design steps can be configured to be performed based on this design principle.

[0204] In a sixth embodiment of the design method, based on the solution of the fourth embodiment of the design method, the step of performing a drop shock simulation analysis on the secondary simulation model is also used to obtain the stress result of the landing gear and the absorption result of the multi-stage energy absorption structure, and determine whether the secondary simulation model is qualified according to the stress result and the absorption result;

[0205] Among them, the multi-level energy absorption structure includes a first-level absorption structure formed by the bending deformation of the horizontal beam section, a second-level absorption structure formed by the bending deformation of the curved beam section, and a third-level absorption structure formed by the bending deformation of the front warping section. The energy absorption amount of the first-level absorption structure is E1, the energy absorption amount of the second-level absorption structure is E2, and the energy absorption amount of the third-level absorption structure is E3.

[0206] In this embodiment, the landing gear has a multi-stage energy absorption structural characteristic, such as Figure 1 As shown, the horizontal and vertical beam sections of the buffer beam absorb the first level of energy E1 by releasing the bending freedom and deformation, the bending deformation of the curved beam section of the buffer beam absorbs the second level of energy E2, the bending deformation of the front warping section of the slide absorbs the third level of energy E3, and the friction between the anti-wear plate and the ground absorbs the fourth level of energy E4, wherein E1, E2 and E3 are interrelated.

[0207] Optionally in this embodiment, the landing gear further includes an anti-wear plate provided on the lower side of the skid, and the friction between the anti-wear plate and the ground can form a fourth-level absorption structure, and the energy absorption amount of the fourth-level absorption structure is E4.

[0208] In this embodiment, after the static strength analysis meets the deformation coordination conditions, a drop shock simulation analysis is performed to obtain the landing gear stress, energy absorption of each level (including E1 to E4), and overload analysis results, so as to provide a basis for judging the performance of the landing gear, thereby determining whether the design of the landing gear meets the requirements. If it does not meet the requirements, repeated analysis and verification can be performed by adjusting relevant structural parameters.

[0209] Among them, if the energy absorption capacity of the first-level absorption structure needs to be adjusted, the spacing d, the tube diameter and tube wall thickness of the buffer beam, etc. can be adjusted; if the energy absorption capacity of the second-level absorption structure needs to be adjusted, the tube diameter and tube wall thickness of the buffer beam, the bending radius and length of the bending beam section, etc. can be adjusted; if the energy absorption capacity of the third-level absorption structure needs to be adjusted, the tube diameter and tube wall thickness of the front warping section of the slide, the bending radius and length of the front warping section, etc. can be adjusted; if the energy absorption capacity of the fourth-level absorption structure needs to be adjusted, the material, wall thickness, contact area with the ground, etc. of the anti-wear plate can be adjusted.

[0210] It can be understood that as a multi-parameter coupling process, the landing performance of the landing gear depends on multiple objectives of the kinematic and dynamic performance of the mounting bracket, buffer beam, skid, etc. These objectives are generally contradictory, and it is very challenging to achieve the best of each indicator at the same time. The multi-objective optimization of the landing gear landing process requires the coordination of each indicator so that each indicator is at the most optimized level as possible, the optimization of the objective function setting and problem solving, and the consideration of the comprehensive benefits of the landing gear landing performance under multiple objectives.

[0211] In the field of multi-objective optimization design, a large number of studies have shown that when dealing with multi-objective optimization problems, the most direct and effective method is to set importance weights for each objective and transform it into a single-objective problem, but the choice of weights has a great influence on the final optimization results.

[0212] The method of converting multiple objectives into a single objective by linear weighting can be adopted to make the objective decision more biased. The landing performance of the landing gear is optimized based on the genetic algorithm. First, the dynamic model of the landing gear is established, and then the sensitivity of each model parameter to each optimization index is calculated. The landing gear design parameters are determined according to the sensitivity, and the multi-objective model of the landing gear parameters is established by using the comprehensive weighting method and the subjective and objective combined weighting method. The comprehensive benefit is used as the fitness function in the genetic algorithm, and finally the landing gear parameter combination that achieves the best comprehensive benefit is determined.

[0213] The parameters involved in the multi-objective optimization of the present invention include, but are not limited to, the wind resistance, weight, strength, stiffness, energy absorption efficiency, and overall layout of the landing gear, and iterative design is performed accordingly to obtain the optimal solution. The relevant design analysis is relatively mature, so it will not be elaborated here.

[0214] In the seventh embodiment of the design method, based on the solution of the first embodiment of the design method, step S120 specifically includes steps S121 to S127:

[0215] Step S121, constructing a one-dimensional beam unit model of the landing gear according to the initial wireframe model of the landing gear, and performing static performance analysis;

[0216] If the static performance of the one-dimensional beam element model does not meet the requirements, perform the following steps:

[0217] Step S122, optimizing and iterating the one-dimensional beam unit model until the one-dimensional beam unit model meets the static performance requirements;

[0218] If the static performance of the one-dimensional beam element model meets the requirements, perform the following steps:

[0219] Step S123, performing dynamic simulation analysis on the one-dimensional beam unit model;

[0220] If the dynamic performance of the one-dimensional beam element model does not meet the requirements, perform the following steps:

[0221] Step S124, optimizing and iterating the one-dimensional beam unit model until the one-dimensional beam unit model meets the dynamic performance requirements;

[0222] If the dynamic performance of the one-dimensional beam element model meets the requirements, the following steps are performed:

[0223] Step S125, constructing a two-dimensional shell element model of the landing gear according to the one-dimensional beam element model, and performing static analysis;

[0224] If the static performance of the two-dimensional shell element model does not meet the requirements, perform the following steps:

[0225] Step S126, optimizing and iterating the two-dimensional shell element model until the two-dimensional shell element model meets the static performance requirements;

[0226] If the static performance of the two-dimensional shell element model meets the requirements, perform the following steps:

[0227] Step S127: output the corresponding two-dimensional shell unit model as a qualified landing gear primary simulation model.

[0228] In this embodiment, when constructing the primary simulation model of the landing gear, two versions of finite element models are successively used, which are used for scheme design and parameter design respectively. Specifically, the scheme design model is composed entirely of one-dimensional beam units, and the connection between parts adopts the common node method, which can carry out rapid iteration and change, and has high calculation efficiency. The parameter design model is based on the preliminary structural model to establish a more detailed two-dimensional shell unit model, and the connection between parts still adopts the common node method. Among them, when the one-dimensional beam unit model is optimized and iterated based on the static analysis results until it meets the requirements, the force transmission path of the structure can be optimized and the structural stress concentration can be reduced; when the one-dimensional beam unit model is optimized and iterated based on the dynamic simulation results until it meets the requirements, it is necessary to pay attention to the natural mode and impact response of the structure; when the two-dimensional shell unit model is optimized and iterated based on the static analysis results, it is necessary to pay attention to the stress distribution of the parts under the working conditions, and determine the structural detail parameters such as the diameter of the round tube, the wall thickness, etc.

[0229] In this embodiment, by simplifying the connection structure of the skid and the buffer beam (including the first joint and the second joint, etc.) into a common node connection mode in the primary simulation model of the landing gear, a preliminary simulation analysis is performed to clarify the structural form of the landing gear; if the mechanical properties of the primary simulation model of the landing gear meet the requirements, the connection structure is further refined and further simulated and analyzed to clarify the specific structure of the connection structure. In this way, the amount of calculation of the computer simulation analysis can be significantly reduced, and the design optimization ideas of the landing gear can be quickly clarified, thereby shortening the design cycle of the landing gear.

[0230] It should be pointed out that the above-mentioned design steps including static strength analysis, drop simulation analysis, etc. can be implemented through software but are not limited to it.

[0231] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A landing gear, characterized in that: include: There are at least two slides, and the two slides are arranged opposite to each other; at least two buffer beams are provided, the buffer beams connect the two slides and protrude upward, the buffer beams have a transverse beam section capable of elastic deformation and two curved beam sections, the curved beam sections are connected between the transverse beam section and the slide; and At least two mounting brackets are used to connect the aircraft body, the two mounting brackets are arranged at opposite ends of a horizontal beam section, and the spacing between the two mounting brackets is d, the width of the landing gear in the distribution direction of the mounting brackets is D, 0.3≤d / D≤0.

7.

2. The landing gear according to claim 1, characterized in that At least two of the buffer beams include a front beam, and a curved beam section of the front beam is bent and extended outwardly toward the rear side and butted against the front end of the slide.

3. The landing gear according to claim 2, characterized in that: The front end of the slide has a front warping section extending upward toward the front, the front warping section protrudes outward and is connected to the curved beam section of the front beam; the rear end of the slide has a rear warping section extending upward toward the rear, and the radii of the rear warping section, the front warping section and the curved beam section are configured to be the same.

4. The landing gear according to claim 2, characterized in that: The landing gear also includes a first joint, and the front beam and the slide are respectively inserted at opposite ends of the first joint; the front beam and / or the slide are fixedly connected to the first joint through a connecting piece, and / or the ratio of the depth of the front beam inserted into the first joint to the diameter of the front beam is in a range of 1 to 2, and / or the ratio of the depth of the slide inserted into the first joint to the diameter of the slide is in a range of 1 to 2.

5. The landing gear according to claim 1, characterized in that: The material of the buffer beam is spring steel, and the material of the slide is deformed aluminum alloy; And / or, the buffer beam and / or the skid is a tubular structure, and the cross-sectional shape is circular, elliptical or polygonal; And / or, the landing gear further comprises an anti-wear sheet, and the anti-wear sheet is arranged on the lower side of the skid; And / or, at least two of the buffer beams include a rear beam, and the landing gear also includes a second joint, the second joint is provided with a socket and a buckle groove, the end of the rear beam is inserted into the socket and fixed by bolts, and the buckle groove is buckled on the upper side of the skid and fixed by rivets.

6. The landing gear according to claim 1, characterized in that The mounting bracket includes a mounting seat and a stop structure, wherein the mounting seat is connected to the aircraft body, and the stop structure connects the mounting seat and the buffer beam to limit the mounting seat from being separated from the buffer beam in the up and down direction; The side wall of the mounting seat is provided with a yielding groove with a notch facing downwards, and the anti-slip structure includes an anti-slip boss, an installation boss and a locking piece. The anti-slip boss extends outward from the notch edge of the yielding groove, and the installation boss is installed on the buffer beam. The yielding groove can be sleeved on the installation boss from top to bottom, and the locking piece can be detachably installed on the installation boss and abut against the upper side of the anti-slip boss.

7. The landing gear according to claim 6, characterized in that The mounting boss is a stud, and the locking member includes a nut and an anti-slip washer, the nut is locked on the mounting boss, and the anti-slip washer is clamped on the mounting seat, and the anti-slip washer abuts against the upper side of the anti-slip boss; And / or, the nut is a slotted nut, and the slotted nut is fixed in the circumferential direction relative to the stud by a cotter pin; And / or, a connecting gap between the nut and the stud is filled with protective glue.

8. The landing gear according to claim 1, characterized in that The mounting bracket further includes a hoop, the hoop including a first hoop body and a second hoop body connected to each other, the first hoop body and the second hoop body jointly clamp the buffer beam and enable the hoop to rotate around an axis extending in the left-right direction; the first hoop body is arranged above the second hoop body and is used to connect the aircraft body; and / or, the mechanical strength of the first hoop body is greater than that of the second hoop body; And / or, the first hoop body and the second hoop body are provided with reinforcing ribs, and the reinforcing ribs surround the outer circumference of the clamp along the front-rear direction of the landing gear, the number of reinforcing ribs on the first hoop body is greater than the number of reinforcing ribs on the second hoop body, and the multiple reinforcing ribs on the first hoop body are arranged along the left-right direction of the landing gear.

9. The landing gear according to claim 1, characterized in that: The landing gear further comprises a limit bracket, which is arranged on the buffer beam and cooperates with the mounting bracket to limit the lateral displacement of the mounting bracket; The limit brackets are provided with two and are located at the interval between the two mounting brackets on the same buffer beam, and the limit bracket abuts against the end face of the mounting bracket close to the other mounting bracket; and / or the limit bracket is configured as a clamp and is arranged on the peripheral side surface of the buffer beam.

10. The landing gear according to claim 9, characterized in that The mounting bracket has a mounting channel, the buffer beam is passed through the mounting channel, a stop flange is extended inwardly from the end surface of the mounting channel, and the outer end surface of the stop flange abuts against the limit bracket.

11. A landing gear according to any one of claims 1 to 10, characterized in that The mounting bracket has a mounting channel, the buffer beam is arranged in the mounting channel, and the landing gear also includes a shock-absorbing pad capable of elastic deformation, the shock-absorbing pad is arranged between the side wall surface of the mounting channel and the peripheral side surface of the buffer beam; a stop flange extends inwardly from the end surface of the mounting channel, and the inner end surface of the stop flange abuts against the end surface of the shock-absorbing pad; And / or, at least two of the buffer beams include a front beam and a rear beam, the transverse and vertical beam sections of the front beam and the rear beam are each provided with at least two of the mounting brackets, the rear beam is arranged close to the center of gravity of the aircraft, and the d / D value on the rear beam is smaller than the d / D value on the front beam; And / or, 0.45≤d / D≤0.

5.

12. A landing gear design method, characterized in that: Includes steps: Constructing an initial wireframe model of the landing gear; wherein the initial wireframe model includes two skids of the landing gear and a buffer beam connected between the two skids, the buffer beam includes a transverse beam section and a curved beam section, the curved beam section is connected between the transverse beam section and the skid, two fuselage mounting points are respectively arranged at opposite ends of the transverse beam section, and the distance between the two fuselage mounting points is d; Constructing a primary simulation model of the landing gear according to the initial wireframe model, and performing mechanical analysis and modal analysis; If the results of the mechanical analysis and modal analysis of the primary simulation model meet the requirements, the primary simulation model is judged to be qualified; If not, the primary simulation model is optimized and iterated until the analysis result meets the requirements; The value of the distance d is determined according to a qualified primary simulation model.

13. The landing gear design method according to claim 12, characterized in that: The landing gear design method further comprises the steps of: According to the primary simulation model and the connection structure connecting the skid and the buffer beam, a secondary simulation model of the landing gear is constructed; wherein the bending radius of the bending beam section of the secondary simulation model is R G ; Perform a drop simulation analysis on the secondary simulation model to determine the minimum bending radius R of the curved beam segment. Gm ; Wherein, the bending radius R G Greater than the minimum bending radius R Gm .

14. The landing gear design method according to claim 13, characterized in that: The skid of the secondary simulation model is provided with a rear warping section at the rear end, and the bending radius of the rear warping section is R R The step of performing a drop shock simulation analysis on the secondary simulation model is also used to determine the minimum unyielding radius R of the rear warping section of the landing gear when the landing gear is later turned over and landed. Rm ; Wherein, the bending radius R R Greater than the minimum unyielding radius R Rm ; And / or, the slide of the secondary simulation model is provided with a front warping section at the front end, and the bending radius of the front warping section is R F The step of performing a drop simulation analysis on the secondary simulation model is also used to determine the minimum bending radius R of the front warping section. Fm ; Wherein, the bending radius R F Greater than the minimum bending radius R Fm .

15. The landing gear design method according to claim 14, characterized in that: The bending radius R G , bending radius R R and bending radius R F The value of is the same and is greater than the minimum bending radius R Gm , minimum unyielding radius R Rm and minimum bending radius R Fm The largest one among them.

16. The landing gear design method according to claim 14, characterized in that: The step of performing a drop shock simulation analysis on the secondary simulation model is also used to obtain the stress result of the landing gear and the absorption result of the multi-stage energy absorption structure, and determine whether the secondary simulation model is qualified according to the stress result and the absorption result; Among them, the multi-level energy absorption structure includes a first-level absorption structure formed by the bending deformation of the horizontal beam section, a second-level absorption structure formed by the bending deformation of the curved beam section, and a third-level absorption structure formed by the bending deformation of the front warping section. The energy absorption amount of the first-level absorption structure is E1, the energy absorption amount of the second-level absorption structure is E2, and the energy absorption amount of the third-level absorption structure is E3.

17. An aircraft, characterized in that: The invention comprises an aircraft body and a landing gear according to any one of claims 1 to 11, wherein the landing gear is arranged on the lower side of the aircraft body.

Images