Aircraft seat vibration reduction system and design method thereof

Abstract

The invention discloses an aircraft seat vibration reduction system and a design method thereof, and belongs to the technical field of aircraft structure dynamic strength. The system comprises two shock absorbers which are distributed left and right, and each shock absorber is composed of a shell, a spring piston rod system, a wear-resisting system, a movement connecting piece and a fastening screw. The spring piston rod system is contained in the shell and keeps a radial gap of 1-2 mm with the inner wall of the shell, a piston rod of the spring piston rod system is coaxial with the shell, and an upper spring and a lower spring are connected in parallel and pre-compressed. The design method comprises the following steps: determining a vibration isolation target frequency based on a seat joint PSD curve; calculating system design frequency and total rigidity; calculating single-spring rigidity according to the parallel structure and determining geometric parameters of the single-spring rigidity; the sizes of all parts are designed in a coordinated mode, and interference inspection is conducted; and finally manufacturing and installing. The system is compact in structure, adjustable in rigidity, high in vibration isolation rate and scientific in design method, vibration transmitted from an aircraft body to the seat can be effectively attenuated, and the problems that the vibration environment of the aircraft seat is difficult to predict, and later optimization is difficult are solved.

Description

Technical Field

[0001] This invention belongs to the field of aircraft structural dynamic strength technology, and specifically relates to an aircraft seat vibration reduction system and its design method. Background Technology

[0002] When an aircraft is in flight, it inevitably vibrates due to aerodynamic loads, engines, and onboard equipment. These vibrations are transmitted through the fuselage structure to the pilot's seat, causing discomfort and affecting the pilot's piloting skills and precise control of weapon systems. In severe cases, they may even induce flight accidents.

[0003] Traditional aircraft seat design typically focuses on the static and dynamic characteristics of the seat itself, lacking effective means to predict vibration transmission from fuselage joints after installation. Vibration problems often only become apparent during flight testing. However, by this time, the aircraft has already entered or completed its airworthiness certification phase, and any minor modifications to the aircraft structure or seat system can trigger a recertification process, resulting in significant workload and cost. Furthermore, the dynamic coupling between the aircraft structure and the seat system is complex, making its optimization design itself a challenge.

[0004] Therefore, there is an urgent need for a vibration reduction system and supporting design method that is simple in structure, highly efficient in vibration isolation, easy to install and does not affect the original performance of the aircraft, so as to effectively attenuate the vibration transmitted to the seat in the later stage of aircraft design or modification, and ensure the safety and comfort of the pilot. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies, such as the difficulty in predicting aircraft seat vibration and the challenges in subsequent vibration reduction optimization, by providing an aircraft seat vibration reduction system and its design method. This system can be directly installed at existing seat joints, utilizing its single-frequency vibration isolation characteristics to significantly reduce the vibration level transmitted from the aircraft to the seat. Its design method is based on measured vibration environments, is scientific and efficient, and enables rapid customization of the system design.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an aircraft seat vibration damping system, which includes two dampers that are symmetrically or asymmetrically distributed.

[0007] Each shock absorber includes a housing, a spring-piston rod system, a wear-resistant system, a moving connector, and fastening screws.

[0008] The housing includes a straight cylinder and left and right connecting lugs located on the sides of the straight cylinder. The top of the straight cylinder has a pre-drilled internal thread, a pre-drilled groove for a retaining spring is machined on the top end face, and a bottom hole is opened at the bottom. The left and right connecting lugs have mounting holes for connection to an aircraft seat connector via bolts; their specific shape and size can be adjusted according to the position of the seat connector connection hole and the supporting surface. The spring piston rod system and the wear-resistant system are housed within the straight cylinder of the housing; The spring piston rod system includes a piston rod and an upper spring and a lower spring coaxially mounted on the piston rod. The piston rod is coaxially arranged with the straight cylinder of the housing. The lower end of the piston rod is machined with external threads and extends out of the bottom hole at the bottom of the housing for threaded connection with the moving connecting parts. The wear-resistant system includes an upper washer, a lower washer, a wear-resistant ring, and a wear-resistant block, which are used to reduce wear between moving parts; The fastening screw is connected to the reserved internal thread on the top of the housing through its external thread, and its lower end face is used to compress the spring piston rod system downward; the reserved groove of the retaining ring is used to install the retaining ring after the fastening screw is tightened to the design position, so as to axially lock the fastening screw and prevent it from loosening.

[0009] Preferably, the piston rod is a one-piece molded structure, including an upper connecting rod, an intermediate platform, and a lower connecting rod. The outer diameter of the intermediate platform is larger than the outer diameters of the upper and lower springs to radially limit the springs; the diameters of the upper and lower connecting rods are smaller than the inner diameters of the springs to ensure that the springs can be smoothly fitted; an annular groove may also be provided on the intermediate platform for installing a wear-resistant ring, the outer ring of which slides in contact with the inner wall of the housing, serving as a guide and providing wear resistance.

[0010] Preferably, there is a radial gap of 1 mm to 2 mm between the outermost radial end of the spring piston rod system and the inner wall of the housing. This gap design avoids direct friction between the spring and the inner wall of the housing, preventing unnecessary dissipation of vibration energy and ensuring vibration isolation efficiency; on the other hand, it provides the necessary guiding space for assembly, ensuring efficient installation.

[0011] Preferably, the upper spring and the lower spring have the same stiffness and geometric dimensions, and are both in a pre-compressed state under the action of the fastening screw. Together, they form a parallel spring structure, which makes the stiffness of a single shock absorber double.

[0012] Preferably, the wear-resistant block in the wear-resistant system has a first boss, a second boss, and a third boss that are nested together; the first boss is positioned in conjunction with the bottom hole of the housing; the second boss is used to avoid the rounded corners of the inner wall of the housing; and the third boss provides a reliable support surface for the lower spring.

[0013] Secondly, the present invention provides a design method for an aircraft seat vibration damping system, comprising the following steps: Obtain the vibration environment power spectral density (PSD) curve at the aircraft seat joint, and extract the frequency of energy concentration as the target frequency for vibration isolation. ; Based on the single-degree-of-freedom vibration isolation theory, the damping ratio and target vibration isolation rate of the seat system are set (usually required to be greater than 80%). The required frequency ratio is then calculated based on the damping ratio and target vibration isolation rate, and subsequently, the target vibration isolation frequency is determined. The design frequency of the vibration reduction system is determined by the frequency ratio. ; Based on the total mass of the seating system (including ejection tubes, seat, and pilot) and design frequency Using the formula Calculate the total stiffness required by the system .

[0014] Based on the structure of the vibration reduction system consisting of two vibration dampers connected in parallel, and each vibration damper containing two parallel springs, calculate the design stiffness of a single spring. Taking into account the constraints of the installation space, determine the geometric parameters of the spring (such as outer diameter, wire diameter, number of effective coils, etc.) that meet this stiffness according to the spring design standards. Based on the above spring geometry parameters, coordinate the design of all relevant dimensions of the shock absorber housing, spring piston rod system, wear-resistant system, moving parts and fastening screws. This process requires the use of 3D modeling software for virtual assembly and interference checks to ensure that the designed shock absorption system does not collide with the structure behind and around the seat. Manufacture all parts according to the final design dimensions, assemble the shock absorbers, and install the assembled shock absorption system at the aircraft seat joint. During assembly, pre-compress the upper and lower springs in the spring piston rod system to the design pre-compression amount by tightening the fastening screws, and then install the snap ring in the snap ring pre-reserved slot of the housing to fix the fastening screws and lock it in place.

[0015] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The vibration reduction system and design method of the present invention provide a brand-new equipment and technical approach for aircraft seat vibration control, avoiding the huge engineering difficulties caused by directly optimizing complex airframe or seat structures. Moreover, the vibration reduction system is stable, has a high vibration isolation rate, and can effectively attenuate seat vibration, ensuring the pilot's safe flight.

[0016] 2. The shock absorber of the present invention achieves four levels of stiffness amplification through the ingenious design of internal double spring parallel pre-compression and external double shock absorber parallel connection, so that the miniaturized structure can provide the required high stiffness, which is particularly suitable for the limited space behind the aircraft seat.

[0017] 3. The design method of this invention is based on measured vibration data, and the design is carried out by reverse engineering starting from the vibration isolation target. The process is clear and the parameters are scientifically determined. The key structural dimensions of the system (such as the shape of the connecting lug, the length of the piston rod, the spring stiffness, etc.) can be adjusted in a coordinated manner according to the specific model and seat environment, which has strong versatility and adaptability.

[0018] 4. The vibration reduction system of the present invention is lightweight and can move in tandem with the seat, without affecting the original core functions and safety margins of the seat such as ejection escape, and has minimal impact on the overall operation of the aircraft. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the aircraft seat vibration reduction system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a single vibration damper in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the breakdown of each subsystem of a single vibration damper in an embodiment of the present invention; Figure 4 This is a schematic diagram of the shell structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the spring piston rod system in an embodiment of the present invention; Figure 6 This is a schematic diagram of the piston rod structure in an embodiment of the present invention; Figure 7 This is a schematic diagram of the wear-resistant system structure in an embodiment of the present invention; Figure 8 This is a schematic diagram of the motion connector structure in an embodiment of the present invention; Figure 9 This is a schematic diagram of the fastening screw structure in an embodiment of the present invention; Figure 10 The diagram shows a variation of the vibration damping system with different left and right connecting lug shapes and piston rod lengths. Detailed Implementation

[0020] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] like Figures 1 to 10 As shown, the core of the aircraft seat vibration reduction system provided by the embodiment of the present invention is that it includes two vibration dampers installed in parallel at the seat joint.

[0023] like Figure 2 and Figure 3 As shown, a single shock absorber mainly consists of five parts: housing 1, spring piston rod system 2, wear-resistant system 3, moving connecting parts 4, and fastening screws 5.

[0024] like Figure 4 As shown, housing 1 is the support and enclosure structure of the shock absorber. For example, housing 1 is a metal housing. Its main body is a straight cylinder 102, and the side of the straight cylinder 102 is provided with left and right connecting ears 101. The connecting ears 101 have mounting holes for fixing to the aircraft seat connector using standard bolts. The shape, size, and included angle of the left and right connecting ears 101 can be customized according to the specific location of the connecting holes and the supporting plane of the aircraft seat connector to ensure a good fit and force distribution.

[0025] The top of the straight cylinder 102 is machined with a reserved internal thread 103 for connecting the fastening screw 5. A retaining ring groove 105 is also machined on the top end face of the straight cylinder 102. Its position is such that after the fastening screw 5 is fully tightened, the groove is located above the screw head for installing the retaining ring for locking. The top of the straight cylinder 102 also includes a top thickened area 104 extending downwards from the top to completely cover the reserved internal thread 103. The bottom of the straight cylinder 102 has a bottom hole 106, the centerline of which coincides with the centerline of the straight cylinder 102, for the extension of the lower end of the piston rod 203 and the positioning of the wear-resistant block 304.

[0026] like Figure 5 and Figure 6 As shown, the spring-piston rod system 2 is the core component that provides stiffness and achieves vibration reduction. The spring-piston rod system 2 includes an upper spring 201, a lower spring 202, and a piston rod 203, and is housed within the straight cylinder 102 of the housing 1.

[0027] The piston rod 203 is preferably integrally machined to ensure coaxiality and strength. Its structure consists of three sections: an upper connecting rod 20301, an intermediate platform 20302, and a lower connecting rod 20303. The outer diameter of the intermediate platform 20302 is designed to be larger than the outer diameters of the upper spring 201 and the lower spring 202, serving to radially limit the springs and prevent excessive bending or displacement during compression. The diameters of the upper connecting rod 20301 and the lower connecting rod 20303 are designed to be smaller than the inner diameter of the springs to allow for smooth assembly.

[0028] The piston rod 203 is strictly coaxial with the straight cylinder 102 of the housing 1, which is crucial to ensuring the smooth operation and uniform force distribution of the shock absorber. The lower connecting rod 20303 of the piston rod 203 has external threads machined at its end.

[0029] The upper spring 201 and the lower spring 202 have identical geometric dimensions, including stiffness, material, outer diameter, and free length. They are coaxially mounted on the piston rod 203, located on the upper and lower sides of the intermediate platform 20302, respectively. After the entire spring-piston rod system 2 is installed inside the housing 1, a uniform gap of 1mm to 2mm is maintained between its outermost radial end (i.e., the outer surface of the spring) and the inner wall of the straight cylinder 102. This gap design has significant effects: firstly, it avoids direct dry friction between the spring and the metal housing, preventing vibration energy from being converted into heat energy and dissipating, thus ensuring vibration isolation efficiency; secondly, it provides necessary guidance and tolerance space for the assembly process, allowing the piston rod system to be smoothly installed into the straight cylinder, improving assembly efficiency and quality. At the same time, the end of the lower connecting rod 20303 extends out of the bottom hole 106, and the external thread on it is used to connect the motion connecting part 4.

[0030] like Figure 7 As shown, the wear-resistant system 3 is used to reduce wear on various contact surfaces during operation and extend service life. It includes an upper washer 301, a wear-resistant ring 302, a lower washer 303, and a wear-resistant block 304. The centerline of the entire wear-resistant system 3 coincides with the centerline of the piston rod 203.

[0031] The upper washer 301 and the lower washer 303 are the same size and are located at the top of the upper spring 201 and the bottom of the lower spring 202, respectively, providing a flat pressure surface for the spring.

[0032] The wear-resistant ring 302 is made of wear-resistant material (such as polytetrafluoroethylene, wear-resistant nylon, etc.) and is installed in a specially machined annular groove on the intermediate platform 20302 of the piston rod 203. The outer ring of the wear-resistant ring 302 protrudes slightly from the intermediate platform 20302 and forms a sliding fit with the inner wall of the straight cylinder 102 of the housing 1. Its function is to guide the piston rod to move along the axis and withstand any small lateral forces that may be generated, protecting the piston rod and the inner wall of the housing from wear.

[0033] The wear-resistant block 304 is a composite part with multiple layers of bosses, located below the lower washer 303. The wear-resistant block 304 includes a first boss 30401, a second boss 30402, and a third boss 30403 nested together. Each of the three bosses has a through hole of the same size in its center, serving as the central hole of the wear-resistant block 304, through which the piston rod 203 passes. The first boss 30401 is installed within the bottom hole 106 of the housing 1, precisely fitting with the bottom hole 106 to achieve radial positioning. The diameter of the second boss 30402 is larger than that of the first boss 30401, used to avoid interference by accommodating the rounded corner at the transition between the inner surface of the straight cylinder 102 of the housing 1 and the bottom. The diameter of the third boss 30403 is between the outer diameter of the spring and the inner diameter of the housing, and its top surface serves as the support surface for the lower washer 303 and the lower spring 202. The function of the wear-resistant block 304 is to provide stable and reliable support for the lower spring and to isolate the piston rod from metal contact with the bottom of the housing.

[0034] like Figure 8 As shown, the motion connector 4 is a connecting conversion component. Its top has an internal thread 401, which connects to the threaded connection at the lower end of the piston rod 203. Its left and right planes are perpendicular to the connection plane of the seat connector. A circular through hole 402 is provided in the middle, which aligns with the through hole at the bottom of the ejector tube and the O-ring hole of the seat connector. A long screw passes through this hole to connect them, thereby achieving linkage between the shock absorber, the seat, and the ejector tube.

[0035] like Figure 9 As shown, the fastening screw 5 has an internal hexagonal hole 501 at its top for easy operation with an internal hexagonal wrench. Its shank is machined with external threads for screwing into the pre-drilled internal thread 103 at the top of the housing 1. During tightening, the lower end face of the screw ultimately presses against the upper washer 301, thereby compressing the entire spring piston rod system 2.

[0036] The overall shape of the shock absorber and the extension length of the piston rod 203 can be adjusted according to the space behind the seat, the number and position of connection points, to prevent collisions. Figure 10 As shown, it illustrates a schematic diagram of a variation of the vibration damping system with different left and right connecting lug shapes and piston rod lengths compared to the aforementioned left and right connecting lugs and piston rods.

[0037] Installation and working principle of the vibration reduction system described in this embodiment of the invention: The assembly sequence of the shock absorber is as follows: First, the first boss of the wear-resistant block 304 is inserted into the bottom hole 106 of the housing 1. Next, the wear-resistant ring 302 is installed in the annular groove of the intermediate platform of the piston rod 203. The lower spring 202 is then installed onto the lower connecting rod 20303 of the piston rod, with its top contacting the bottom of the intermediate platform 20302. The lower washer 303 is then installed, contacting the bottom of the lower spring 202. This assembly is then placed into the housing 1, allowing the lower connecting rod 20303 to pass through the center hole of the wear-resistant block 304, leaving it in a free state. Finally, the upper spring 201 and the upper washer 301 are inserted into the straight cylinder 102 from the top of the housing. Then, the fastening screw 5 is rotated into the reserved internal thread 103 of the housing 1. Because of the reserved thread length, the lower end of the fastening screw 5 does not initially contact the upper washer 301. After rotating a certain length, the fastening screw 5 begins to contact the upper washer 301, thereby compressing the upper spring 201. The force is transmitted through the piston rod, and the lower spring 202 is also compressed. The entire spring-piston rod system changes from a free state to a pre-compressed state. The lower connecting rod 20303 of the piston rod moves downward, extending more length beyond the bottom hole 106 of the housing. The pre-compression amount is determined according to design calculations to ensure that the system is at its optimal operating point after the pilot sits on it. After pre-compression is in place, the retaining circlip is installed in the retaining circlip groove 105, and the fastening screw 5 is locked. The other shock absorber is assembled following the same steps.

[0038] Finally, install the vibration damping system: use bolts to fix the two shock absorbers to both sides of the seat joint through the pre-drilled holes in the left and right connecting lugs 101. Using the original long screws of the seat system, pass them sequentially through the left O-ring hole of the seat joint, the through hole of the motion connector of the left shock absorber, the through hole of the ejector tube, the through hole of the motion connector of the right shock absorber, and the right O-ring hole of the seat joint, and finally tighten the nuts.

[0039] Once the pilot is seated, the vibration damping system activates. Vibrations from the fuselage are transmitted through the seat joint, attempting to move the damper housing 1. However, due to the inertia and elasticity of the spring-piston rod system 2, most of the vibration energy is offset, significantly reducing the vibration transmitted to the moving connector 4 and the seat body, thereby protecting the pilot.

[0040] This invention also provides a design method for an aircraft seat vibration reduction system, which is used to design the above-mentioned vibration reduction system, and specifically includes the following steps: S1. Determine the target frequency for vibration isolation.

[0041] This step obtains the vibration environment PSD curve at the aircraft seat joint and extracts the energy concentration frequency as the target frequency for vibration isolation. .

[0042] Specifically, flight test data of the target aircraft model is collected, with a focus on analyzing the vibration environment at the seat joint mounting location to obtain the vibration environment power spectral density (PSD) curve. The frequency range in the curve where vibration energy is most concentrated is identified, and the center frequency of this range is taken as the target vibration isolation frequency that needs to be isolated. .

[0043] S2. Determine the design frequency of the vibration reduction system.

[0044] This step, based on single-degree-of-freedom vibration isolation theory, sets the damping ratio and target isolation rate of the seat system, calculates the required frequency ratio based on the damping ratio and target isolation rate, and then determines the target isolation frequency. The design frequency of the vibration reduction system is determined by the frequency ratio. .

[0045] Specifically, the seating system (ejector-seat-pilot) is simplified into a single-degree-of-freedom system. Based on engineering experience, the damping ratio of this system is... A damping ratio typically ranges from 0.03 to 0.1. This is a dimensionless parameter representing the degree of energy dissipation in the vibrating system. It sets the target vibration isolation rate that the system needs to achieve. According to the vibration isolation ratio formula for a single-degree-of-freedom system:

[0046] It can be seen that only when the frequency is greater than... hour, Only with proper vibration isolation can vibration be achieved. To ensure the vibration reduction effect, the vibration isolation rate must be... Typically, a vibration isolation rate greater than 80% is required when determining the target vibration isolation rate. Then, by substituting the values ​​into the above formula, the desired frequency ratio can be obtained. Furthermore, based on the target vibration isolation frequency... Ratio to frequency Determine the design frequency of the vibration reduction system itself. The calculation formula is: , It should be much smaller .

[0047] S3. Calculate the total stiffness of the vibration reduction system.

[0048] This step is based on the total mass of the seating system. and design frequency Using the formula Calculate the total stiffness required for the vibration reduction system .

[0049] Specifically, estimate or measure the total mass of the seating system (ejector, seat, and pilot). Using the frequency calculation formula The total stiffness required for the vibration reduction system can be determined. . S4. Determine the design stiffness of a single spring. and geometric parameters This step calculates the design stiffness of a single spring based on the structure of the vibration reduction system, which consists of two vibration dampers connected in parallel, and each vibration damper containing two parallel springs. The geometric parameters of the spring are determined based on the installation space constraints and stiffness requirements.

[0050] Specifically, since the vibration damping system uses two dampers connected in parallel, and each damper contains two springs working in parallel, the design stiffness of a single spring is... .

[0051] According to the calculation And the allowable installation space for the shock absorber behind the seat (roughly determining the spring's installation height and outer diameter range), referring to national standards such as GB / T 2089-2009 "Dimensions and Parameters of Ordinary Cylindrical Helical Compression Springs" and GB / T 1239.6-2009 "Design Calculation of Cylindrical Helical Springs," etc., determine a set of suitable spring geometric parameters through calculation or table lookup, including spring wire diameter, spring inner diameter, spring outer diameter, effective number of coils, free length, etc., so that the spring stiffness is equal to... Based on this, springs that meet the requirements can be manufactured.

[0052] S5. Coordinate the design of part dimensions and perform interference checks. This step uses the geometric parameters of the aforementioned spring as a benchmark to coordinate the design of the dimensions of the shock absorber housing 1, spring piston rod system 2, wear-resistant system 3, moving connector 4, and fastening screw 5, and performs interference checks to ensure that the shock absorption system does not collide with the structure behind the seat.

[0053] Specifically, using the spring dimensions determined in the previous step as the design origin, we can then proceed with the detailed design of all other parts: The diameter of the piston rod 203 (upper and lower connecting rods) is determined based on the inner diameter of the spring and must be slightly smaller than the inner diameter of the spring. The inner diameters of the upper washer 301, lower washer 303, and wear-resistant block 304 are designed to match the piston rod 203. For example, the inner diameters of the upper washer 301, lower washer 303, and wear-resistant block 304 can be designed to be equal to the diameter of the piston rod 203.

[0054] Based on the outer diameter of the spring, the inner diameter of the housing cylinder 102 is determined, and it must be larger than the outer diameter of the spring with a 1-2mm gap. The outer diameters of the upper washer 301, lower washer 303, piston rod intermediate platform 20302, and wear-resistant block third boss 30403 are designed to be between the outer diameter of the spring and the inner diameter of the cylinder 102.

[0055] Based on the inner diameter of the housing cylinder 102, the outer diameter of the wear-resistant ring 302 is designed so that it can make good contact with the inner wall of the cylinder 102; based on the size of the annular groove on the piston rod intermediate platform 20302, the inner diameter of the wear-resistant ring 302 is designed so that the inner ring of the wear-resistant ring 302 is tightly fitted into the annular groove.

[0056] A bottom hole 106 is designed at the bottom of the housing 1. The inner diameter of the bottom hole 106 is larger than the diameter of the piston rod 203. This ensures that the diameter of the first boss 30401 of the wear-resistant block is equal to the inner diameter of the bottom hole, and the height is equal to the thickness of the bottom of the housing 1. The diameter of the second boss 30402 is smaller than the minimum diameter of the rounded corner of the inner wall of the straight cylinder 102. The diameter of the third boss 30403 is smaller than the inner diameter of the straight cylinder 102.

[0057] The top of the housing is designed with a reserved internal thread 103, the inner diameter of which is larger than the inner diameter of the straight cylinder 102. The external thread of the fastening screw 5 is designed in coordination. The length of the reserved internal thread 103 must be greater than the external thread of the fastening screw 5. At the same time, the vertical height from the upper washer 301 to the top of the reserved internal thread 103 must be greater than the height of the external thread of the fastening screw 5. The length of the thickened area at the top must be greater than the length of the reserved internal thread 103. The top of the fastening screw 5 is designed with an internal hexagonal hole according to the relevant standards in the mechanical manual, which facilitates installation with a hexagonal wrench.

[0058] A retaining ring groove 105 is designed on the top of the housing 1 to ensure that when the fastening screw 5 is fully tightened, the retaining ring groove 105 is located above the fastening screw 5. An external thread is designed at the bottom of the piston rod 203, and the internal thread 401 of the motion connector 4 is designed in coordination to ensure that the thread depths of the two are consistent. The inner diameter of the circular through hole 402 of the motion connector 4 is equal to the inner diameter of the through hole at the bottom of the ejection tube.

[0059] Model all the above parts in 3D modeling software (such as CATIA, UG, etc.) and perform virtual assembly. Using the software's interference check function, simulate the state of the shock absorber after installation onto the specific model's seat joint, checking for spatial interference with the rear structure of the seat, ejection cylinder, pipelines, etc. If a collision occurs, return to step S4, readjust the spring parameters or part contour dimensions, and perform coordination design and interference checks again until all interferences are eliminated. Simultaneously, ensure that the center line of the circular through hole 402 of the moving connector 4 is aligned with the center line of the O-ring hole of the seat joint after assembly.

[0060] S6. Manufacturing, Assembly and Installation This step involves manufacturing and assembling the shock absorber according to the above design dimensions, and then installing the assembled shock absorption system onto the aircraft seat joint.

[0061] Specifically, based on the final 3D model that has passed interference inspection, 2D engineering drawings of all parts are generated for processing and manufacturing. Then, the shock absorber is assembled according to the aforementioned assembly sequence. During the assembly process, a key step is to pre-compress the upper spring 201 and lower spring 202 in the spring-piston rod system 2 by tightening the fastening screws 5 until the pre-compression amount required by the design calculation (i.e., the change in piston rod elongation) is reached. satisfy (where g is the acceleration due to gravity), and then the retaining circlip is installed in the retaining circlip groove 105 of the housing 1 to fix the fastening screw 5 and lock it in place. Finally, the two fully assembled shock absorber systems are installed at the aircraft seat joint.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aircraft seat vibration damping system, characterized in that, It includes two shock absorbers distributed on the left and right sides; the shock absorber includes a housing (1), a spring piston rod system (2), a wear-resistant system (3), a motion connector (4), and a fastening screw (5); The housing (1) includes a straight cylinder (102) and left and right connecting ears (101) provided on the side of the straight cylinder (102). The top of the straight cylinder (102) is provided with a reserved internal thread (103), the top end face of the straight cylinder (102) is provided with a reserved groove for a snap ring (105), and the bottom is provided with a bottom hole (106). The spring piston rod system (2) and the wear-resistant system (3) are housed within the straight cylinder (102) of the housing (1); The spring piston rod system (2) includes an upper spring (201) and a lower spring (202) coaxially mounted on the piston rod (203). The piston rod (203) is coaxially arranged with the straight cylinder (102). The lower end of the piston rod (203) is provided with an external thread and extends out of the bottom hole (106) to connect with the motion connector (4). The fastening screw (5) is connected to the reserved internal thread (103) through its external thread, and the lower end face of the fastening screw (5) is used to compress the spring piston rod system (2); the retaining ring reserved groove (105) is used to accommodate the retaining ring to achieve axial locking after the fastening screw (5) is tightened.

2. The aircraft seat vibration damping system according to claim 1, characterized in that, The piston rod (203) is an integrally formed structure, including an upper connecting rod (20301), an intermediate platform (20302) and a lower connecting rod (20303); the outer diameter of the intermediate platform (20302) is larger than the outer diameter of the upper spring (201) and the lower spring (202), and the diameter of the upper connecting rod (20301) and the lower connecting rod (20303) is smaller than the inner diameter of the upper spring (201) and the lower spring (202).

3. The aircraft seat vibration damping system according to claim 2, characterized in that, The intermediate platform (20302) is provided with an annular groove for installing the wear-resistant ring (302).

4. The aircraft seat vibration damping system according to claim 1, characterized in that, The outermost radial end of the spring piston rod system (2) has a radial gap of 1 mm to 2 mm between it and the inner wall of the straight cylinder (102).

5. The aircraft seat vibration damping system according to claim 1 or 4, characterized in that, The upper spring (201) and the lower spring (202) have the same stiffness and geometric dimensions, and are both in a pre-compressed state, together forming a parallel spring structure.

6. The aircraft seat vibration damping system according to claim 1 or 4, characterized in that, The wear-resistant system (3) includes a wear-resistant block (304), which has a first boss (30401), a second boss (30402) and a third boss (30403) nested together; wherein the first boss (30401) cooperates with the bottom hole (106) and the third boss (30403) provides a support surface for the lower spring (202).

7. A design method for an aircraft seat vibration damping system, characterized in that, Includes the following steps: Obtain the vibration environment PSD curve at the aircraft seat joint and extract the energy concentration frequency as the target frequency for vibration isolation. ; Based on the single-degree-of-freedom vibration isolation theory, the damping ratio and target vibration isolation rate of the seat system are set. The required frequency ratio is then calculated based on the damping ratio and target vibration isolation rate, and finally, the target vibration isolation frequency is determined. The design frequency of the vibration reduction system is determined by the frequency ratio. ; Based on the total mass of the seating system and the design frequency Using the formula Calculate the total stiffness required for the vibration reduction system ; Based on the structure of the vibration reduction system consisting of two vibration dampers connected in parallel, and each vibration damper containing two parallel springs, the design stiffness of a single spring is calculated. And according to the design stiffness Determine the geometric parameters of the spring based on installation space constraints and stiffness requirements; Based on the geometric parameters of the spring, coordinate the design of the dimensions of the shock absorber housing (1), spring piston rod system (2), wear-resistant system (3), motion connector (4) and fastening screw (5), and conduct interference checks to ensure that the shock absorption system does not collide with the structure behind the seat; The shock absorbers are manufactured and assembled according to the design dimensions, and the assembled shock absorption system is installed at the aircraft seat joint.

8. The design method according to claim 7, characterized in that, The target vibration isolation rate is greater than 80%.

9. The design method according to claim 7, characterized in that, According to the formula Calculate the design stiffness of a single spring .

10. The design method according to claim 7, characterized in that, When assembling the shock absorber, the upper spring (201) and lower spring (202) of the spring piston rod system (2) are pre-compressed by tightening the fastening screw (5) to reach the pre-compression amount determined according to the design. Then, a retaining ring is installed in the retaining ring reserved groove (105) of the housing (1) to fix the fastening screw (5).

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