An ISD-based landing gear bumper

Abstract

The application discloses an ISD-based landing gear buffer, which comprises an outer cylinder, an inner cylinder sleeved in the outer cylinder and movable in the outer cylinder, and a plunger assembly arranged in the outer cylinder. The application realizes the introduction of the built-in spiral pipe type hydraulic inertial container into the landing gear buffer by means of the spiral groove formed on the outer wall surface of the plunger head and matched with the inner wall surface of the inner cylinder, so as to form a spiral pipe, thereby forming an ISD (inertial-spring-damping) landing gear buffer. Since the inertial container has the vibration absorption characteristics of passing high frequency and resisting low frequency, and the spring has the vibration absorption characteristics of passing low frequency and resisting high frequency, the two can absorb vibration energy in the full frequency domain through reasonable layout, and meanwhile, part of the vibration energy is dissipated in the form of heat energy through the damping effect of the high-speed flow of the hydraulic oil through the damping hole. The landing gear buffer disclosed by the application can realize full-frequency-domain shock absorption.

Description

Technical Field

[0001] This invention relates to the field of aircraft landing gear technology, and in particular to a landing gear buffer based on ISD. Background Technology

[0002] Landing gear buffers, as a crucial component of aircraft landing gear, play roles in load bearing, shock absorption, and energy dissipation during aircraft parking, takeoff, and landing. To improve the buffering performance of landing gear buffers, their structural forms have been continuously improved, resulting in solid spring buffers, fluid spring buffers, and hydrant-pneumatic buffers. Among these, hydrant-pneumatic buffers offer the highest buffering efficiency and the strongest energy absorption capacity, and are therefore widely used in landing gear and remain in use today.

[0003] Although the landing gear damper structure has been continuously improved, its basic damping mechanism has remained unchanged. It still relies on springs to absorb energy and hydraulic oil flowing at high speed through damping orifices to dissipate energy. Because springs have the vibration absorption characteristics of blocking high frequencies and passing low frequencies, the traditional SD damping mechanism is insufficient in suppressing low-frequency vibrations.

[0004] To address the aforementioned problems, this invention provides a landing gear damper based on ISD, which solves the problem of poor shock absorption performance of previous landing gear dampers. Summary of the Invention

[0005] The purpose of this invention is to provide a landing gear buffer based on ISD, so as to improve the shock absorption effect of the landing gear buffer.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] An ISD-based landing gear buffer includes an outer cylinder, an inner cylinder fitted inside the outer cylinder and movable within the outer cylinder, and a plunger assembly disposed within the outer cylinder. The upper sidewall of the outer cylinder has a first threaded hole for installing an oil injection assembly, and the lower sidewall of the outer cylinder has a second threaded hole for installing an oil discharge assembly. The upper end face of the outer cylinder has a third threaded hole for connecting to the plunger assembly, and the outer wall of the lower end face of the outer cylinder has an external thread for engaging with a cap nut. The plunger assembly includes a plunger mounting head for connecting to the third threaded hole, a plunger tube connected to the plunger mounting head, and a plunger head connected to the plunger tube. The tube wall has several first through holes, and the outer wall of the plunger head has a helical groove that contacts the inner wall of the inner cylinder. A spiral channel is formed. The lower end face of the plunger head is provided with several damping holes. The upper outer wall of the inner cylinder is provided with a first annular groove, and the lower outer wall of the inner cylinder is provided with a second annular groove. An upper support with a second through hole is provided in the first annular groove, and a throttling component is provided in the second annular groove. A lower support is provided near the lower part of the throttling component. The area formed by the outer cylinder, plunger assembly, inner cylinder and upper support forms a gas chamber. The plunger head and the inner cylinder form a main oil chamber. The area between the outer cylinder, inner cylinder, upper support and throttling component forms a transition chamber. The outer cylinder, inner cylinder, throttling component and lower support form a return oil chamber. The main oil chamber is connected to the gas chamber through the spiral channel, several damping holes and several first through holes. The gas chamber is connected to the transition chamber through several second through holes. The transition chamber is connected to the return oil chamber through several throttling holes.

[0008] Preferably, O-rings are provided at the positions where the oil injection assembly and the oil discharge assembly are connected to the first threaded hole and the second threaded hole, respectively.

[0009] Preferably, the sealing nut has a groove inside for installing the skeleton dustproof ring, and the inner diameter of the lip at the lowest end of the skeleton dustproof ring is smaller than the outer diameter of the inner cylinder.

[0010] Preferably, the upper support is a two-part split structure, with several second through holes evenly opened on its end face for hydraulic oil to flow between the air chamber and the transition chamber.

[0011] Preferably, the lower support includes a lower bushing, a bushing, and a support bushing.

[0012] Preferably, the O-ring is arranged between the inner wall of the outer cylinder and the outer wall of the lower bushing, and a Yx-type shaft seal and a retaining ring are arranged between the inner wall of the lower bushing and the outer wall of the inner cylinder.

[0013] Preferably, the throttling assembly includes a brake sleeve and a piston expansion ring. The brake sleeve is fixedly installed in a second annular groove opened on the outer wall of the inner cylinder, and the piston expansion ring is movably installed in an annular groove opened on the outer wall of the brake sleeve. The upper and lower flanges of the brake sleeve are respectively provided with a plurality of grooves, and the piston expansion ring and the plurality of grooves opened on the lower and upper flanges respectively form a plurality of throttling holes.

[0014] Preferably, the number and size of the grooves on the upper flange of the brake sleeve are less than the number and size of the grooves on the lower flange.

[0015] The present invention achieves the following technical effects compared to the prior art:

[0016] 1. This invention introduces a built-in helical tube-type hydraulic inertial container into the traditional SD landing gear buffer structure by creating a helical groove on the outer wall of the plunger head, which mates with the inner wall of the inner cylinder to form a helical tube, thus constituting an ISD landing gear buffer. Since the inertial container has the vibration absorption characteristics of passing high frequencies and blocking low frequencies, while the spring has the vibration absorption characteristics of passing low frequencies and blocking high frequencies, their reasonable arrangement can absorb vibration energy across the entire frequency range. Simultaneously, the damping effect of the hydraulic oil flowing at high speed through the damping orifice dissipates some of the vibration energy as heat, thereby achieving vibration reduction across the entire frequency range.

[0017] 2. Compared to traditional SD landing gear dampers, this invention can suppress low-frequency vibrations, thus reducing wear on related components caused by low-frequency vibrations and improving service life. Furthermore, this invention can, to some extent, prevent loosening of certain mechanical connections in the aircraft due to low-frequency vibrations, thereby reducing maintenance costs and improving safety and reliability.

[0018] 3. The spiral grooves on the outer wall of the plunger head reduce the weight of the landing gear buffer to some extent. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a landing gear buffer based on ISD in its fully extended state according to the present invention;

[0021] Figure 2 This is a schematic diagram of the operation of a landing gear buffer based on ISD under positive stroke compression state according to the present invention;

[0022] Figure 3This is a schematic diagram of the operation of a landing gear buffer based on ISD in the reverse extension state according to the present invention;

[0023] Figure 4a This is a schematic diagram of the throttling assembly structure of a landing gear buffer based on ISD in the positive stroke compression state according to the present invention;

[0024] Figure 4b This is a bottom view of a throttling assembly of a landing gear buffer based on ISD in the positive stroke compression state according to the present invention;

[0025] Figure 5a This is a schematic diagram of the throttling component structure of a landing gear buffer based on ISD in the reverse extension state according to the present invention;

[0026] Figure 5b This is a top view of a throttling assembly of a landing gear buffer based on ISD in the reverse extension state according to the present invention;

[0027] Figure 6 This is a schematic diagram of a plunger head structure for a landing gear buffer based on ISD according to the present invention;

[0028] Wherein: 1-Outer cylinder; 2-Plunger mounting head; 3-O-ring seal; 4-Plunger tube; 5-Screw; 6-First through hole; 7-Upper support; 8-Second through hole; 9-Plunger head; 10-Helical channel; 11-Damping hole; 12-Inner cylinder; 13-Brake sleeve; 14-Piston expansion ring; 15-Upper flange groove; 16-Lower flange groove; 17-Lower flange throttling hole; 18-Upper flange throttling hole; 19-O-ring seal; 20-Oil drain assembly; 21-O-ring seal; 22-Lower bushing; 23-Yx type shaft seal; 24-Retaining ring; 25-Bushing; 26-Support bushing; 27-Cap nut; 28-Skeleton dustproof ring; 29-O-ring seal; 30-Oil filling assembly; Ⅰ-Air chamber; Ⅱ-Main oil chamber; Ⅲ-Transition chamber; Ⅳ-Return oil chamber. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The purpose of this invention is to provide a landing gear buffer based on ISD, so as to improve the shock absorption effect of the landing gear buffer.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] refer to Figures 1 to 6 A landing gear damper based on ISD includes an outer cylinder 1, an inner cylinder 12 sleeved within the outer cylinder 1 and movable within the outer cylinder 1, and a plunger assembly disposed within the outer cylinder. The upper sidewall of the outer cylinder has a first threaded hole for installing an oil injection assembly, the lower sidewall of the outer cylinder has a second threaded hole for installing an oil discharge assembly, and the upper end face of the outer cylinder has a third threaded hole for connecting to the plunger assembly. The lower end face of the outer cylinder has an external thread for engaging with a cap nut 27. The plunger assembly includes a plunger mounting head for connecting to the third threaded hole, a plunger tube 4 connected to the plunger mounting head 2, and a plunger head connected to the plunger tube 4. The plunger tube has several first through holes 6 on its wall, and the plunger head 9 has a helical groove on its outer wall. The helical groove contacts the inner wall of the inner cylinder and forms a helical channel 10. The lower end face of the plunger head has several damping holes. The upper outer wall of the inner cylinder has... The inner cylinder has a first annular groove and a second annular groove on its lower outer wall. An upper support 7 with a second through hole 8 is located within the first annular groove. A throttling assembly is located within the second annular groove, and a lower support is located below the throttling assembly. The area formed by the outer cylinder, plunger assembly, inner cylinder, and upper support forms a gas chamber I. The plunger head and inner cylinder form a main oil chamber II. The area between the outer cylinder, inner cylinder, upper support, and throttling assembly forms a transition chamber III. The outer cylinder, inner cylinder, throttling assembly, and lower support form a return oil chamber IV. The main oil chamber communicates with the gas chamber through a spiral channel, several damping holes 11, and several first through holes. The gas chamber communicates with the transition chamber through several second through holes. The transition chamber communicates with the return oil chamber through several throttling holes. This invention, by creating a spiral groove on the outer wall of the plunger head, which mates with the inner wall of the inner cylinder to form a spiral tube, introduces a built-in spiral tube-type hydraulic inertial container into the traditional SD landing gear buffer structure, thus constituting an ISD landing gear buffer. Since the inertial container has the vibration absorption characteristics of passing high frequencies and blocking low frequencies, while the spring has the vibration absorption characteristics of passing low frequencies and blocking high frequencies, the two can absorb vibration energy in the whole frequency range through reasonable arrangement. At the same time, the damping effect of hydraulic oil flowing through the damping orifice at high speed dissipates some vibration energy in the form of heat energy, thereby achieving vibration reduction in the whole frequency range.

[0033] refer to Figure 1 The plunger head 9 is connected to the plunger tube by screw 5.

[0034] refer to Figure 1O-rings 3 are provided at the positions where the oil injection assembly 30 and the oil discharge assembly 20 are connected to the first threaded hole and the second threaded hole, respectively; wherein, nitrogen is injected into the air chamber and hydraulic oil is injected into the main oil chamber through the oil injection assembly, and oil is discharged through the oil discharge assembly.

[0035] refer to Figure 1 The cap nut 27 has a groove inside for installing the skeleton dust ring. The inner diameter of the lip at the lowest end of the skeleton dust ring 28 is smaller than the outer diameter of the inner cylinder, so that it can fit tightly against the outer wall of the inner cylinder. During the operation of the landing gear buffer, it can scrape off the dust and other dirt exposed on the outer surface of the inner cylinder, preventing the hydraulic oil from being contaminated and the surface of the parts from being scratched.

[0036] Furthermore, the upper support is a two-part split structure, with several second through holes evenly opened on its end face for hydraulic oil to flow between the air chamber and the transition chamber.

[0037] refer to Figure 1 The lower support includes a lower bushing 22, a bushing 25, and a support bushing 26.

[0038] refer to Figure 1 An O-ring seal 3 is arranged between the inner wall of the outer cylinder and the outer wall of the lower bushing 22, and a Yx-type shaft seal 23 and a retaining ring 24 are arranged between the inner wall of the lower bushing 22 and the outer wall of the inner cylinder.

[0039] refer to Figure 4a , Figure 4b , Figure 5a and Figure 5b The throttling assembly includes a brake sleeve 13 and a piston expansion ring 14. The brake sleeve is fixedly installed in a second annular groove on the outer wall of the inner cylinder, and the piston expansion ring is movably installed in the annular groove on the outer wall of the brake sleeve, allowing it to move freely up and down. The upper and lower flanges 16 of the brake sleeve are respectively provided with several grooves. During the compression-elongation process of the inner cylinder, the piston expansion ring and the grooves on the lower and upper flanges respectively form several lower flange throttling holes 17 and upper flange throttling holes 18, through which hydraulic oil flows at high speed, generating damping.

[0040] refer to Figure 4a , Figure 4b , Figure 5a and Figure 5b The number and size of the grooves on the upper flange 15 of the brake sleeve should be less than the number and size of the grooves on its lower flange, so as to ensure that the total cross-sectional area of ​​the throttling holes formed by the piston ring and the grooves on the upper flange is less than the total cross-sectional area of ​​the throttling holes formed by the piston ring and the grooves on the lower flange, thereby preventing the buffer from elongating too quickly.

[0041] The method of using this invention is as follows:

[0042] The compression process during landing and takeoff: The aircraft experiences impact loads with the ground during landing, forcing the inner cylinder to move rapidly upwards relative to the outer cylinder. The landing gear buffer enters the compression phase, and the main oil chamber volume decreases rapidly. A portion of the hydraulic oil within the chamber is forced to flow at high speed through the spiral grooves on the outer wall of the plunger head and into the air chamber. During this process, the linear motion of the inner cylinder is partially converted into the inertial motion of the hydraulic oil within the spiral grooves, thus achieving energy absorption by the inertial container. Simultaneously, a portion of the hydraulic oil in the main oil chamber is forced to flow at high speed through several damping orifices on the plunger head end face and into the plunger tube cavity, then through several first through-holes into the air chamber. During this process, the damping generated by the high-speed flow of hydraulic oil through the damping orifices dissipates some of the impact energy as heat. As the inner cylinder moves upwards, the air chamber volume decreases and the amount of hydraulic oil within the chamber increases, causing the gas within the air chamber to be compressed, thereby converting some of the impact energy into elastic potential energy. Hydraulic oil in the air chamber flows to the transition chamber through several second through holes opened on the upper support end face. Under its own weight and the impact of the hydraulic oil in the transition chamber, the piston expansion ring is pressed tightly against the upper surface of the lower flange of the brake sleeve, thereby forming several lower flange throttling holes, which allows the hydraulic oil in the transition chamber to flow through at high speed and generate damping, and finally flows to the return oil chamber. In this process, some of the impact energy is dissipated again in the form of heat energy.

[0043] Reverse extension process: When the gas in the air chamber is compressed to a certain extent, the pressure inside the chamber exceeds the external impact load borne by the inner cylinder. The inner cylinder begins to move downward relative to the outer cylinder, and the landing gear buffer begins to enter the extension stage. The volume of the return oil chamber decreases, and the bottom of the chamber is sealed. Therefore, the hydraulic oil in the chamber begins to flow from bottom to top, pushing the piston expansion ring to press tightly against the lower surface of the upper flange of the brake sleeve, thus forming several upper flange throttling orifices. This allows the hydraulic oil in the return oil chamber to flow in reverse at high speed and generate damping, and then flows to the transition chamber. In this process, some of the impact energy is dissipated again in the form of heat. The hydraulic oil in the transition chamber flows in reverse to the air chamber through several second through holes opened on the upper support end face. A portion of the hydraulic oil in the air chamber flows in reverse to the main oil chamber through the spiral groove opened on the outer wall of the plunger head at high speed. In this process, the linear motion of the inner cylinder is partially converted into the inertial motion of the hydraulic oil in the spiral groove, thus achieving energy absorption by the inertial container again. At the same time, a portion of the hydraulic oil in the air chamber flows in the reverse direction to the inner cavity of the plunger tube through several first through holes, and then flows at high speed through several damping holes and generates damping, and finally flows to the main oil chamber. In this process, some of the impact energy is dissipated again.

[0044] After multiple compression and elongation phases, the landing gear buffer eventually dissipates the remaining impact energy.

[0045] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0046] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An ISD-based landing gear bumper, characterized by, The application relates to a hydraulic oil pump, which comprises an outer cylinder, an inner cylinder sleeved in the outer cylinder and movable in the outer cylinder, and a plunger assembly arranged in the outer cylinder, a first threaded hole for mounting an oil injection assembly is arranged on the upper end side wall of the outer cylinder, a second threaded hole for mounting an oil discharge assembly is arranged on the lower end side wall of the outer cylinder, a third threaded hole for connecting with the plunger assembly is arranged on the upper end face of the outer cylinder, an outer thread for cooperating with a cover nut is arranged on the lower end face outer wall of the outer cylinder, the plunger assembly comprises a plunger mounting head for connecting with the third threaded hole, a plunger tube connected with the plunger mounting head, and a plunger head connected with the plunger tube, a plurality of first through holes are arranged on the tube wall of the plunger tube, a spiral groove is arranged on the outer wall of the plunger head, the spiral groove is in contact with the inner wall of the inner cylinder and forms a spiral channel, a plurality of damping holes are arranged on the lower end face of the plunger head, a first annular groove is arranged on the upper end outer wall of the inner cylinder, a second annular groove is arranged on the lower end outer wall of the inner cylinder, an upper support provided with a second through hole is arranged in the first annular groove, and a throttling assembly is arranged in the second annular groove; the throttling assembly comprises a brake sleeve and a piston expansion ring, the brake sleeve is fixedly arranged in the second annular groove arranged on the outer wall of the inner cylinder, the piston expansion ring is movably arranged in the annular groove arranged on the outer wall of the brake sleeve, a plurality of grooves are arranged on the upper and lower flanges of the brake sleeve respectively, and the piston expansion ring forms a plurality of throttling holes with the grooves arranged on the upper and lower flanges respectively. A lower support is arranged below the throttling assembly, an air cavity is formed in the region formed by the outer cylinder, the plunger assembly, the inner cylinder and the upper support, a main oil cavity is formed by the plunger head and the inner cylinder, a transition cavity is formed in the region between the outer cylinder, the inner cylinder, the upper support and the throttling assembly, and an oil return cavity is formed by the outer cylinder, the inner cylinder, the throttling assembly and the lower support, the main oil cavity is communicated with the air cavity through the spiral channel, the plurality of damping holes and the plurality of first through holes, the air cavity is communicated with the transition cavity through the plurality of second through holes, and the transition cavity is communicated with the oil return cavity through the plurality of throttling holes.

2. An ISD-based landing gear damper according to claim 1, wherein, O-shaped sealing rings are arranged at the positions where the oil injection assembly and the oil discharge assembly are connected with the first threaded hole and the second threaded hole respectively.

3. An ISD-based landing gear damper according to claim 1, wherein, A groove for mounting a skeleton dustproof ring is arranged in the cover nut, and the inner diameter of the lip at the lowermost end of the skeleton dustproof ring is smaller than the outer diameter of the inner cylinder.

4. An ISD-based landing gear damper according to claim 1, wherein, The upper support is a two-half split structure, and a plurality of second through holes are uniformly arranged on the end faces of the upper support for the flow of hydraulic oil between the air cavity and the transition cavity.

5. An ISD-based landing gear damper according to claim 2, wherein, The lower support comprises a lower shaft sleeve, a bushing and a support shaft sleeve.

6. An ISD-based landing gear damper according to claim 5, wherein, The O-shaped sealing ring is arranged between the inner wall of the outer cylinder and the outer wall of the lower shaft sleeve, and a Yx-shaped shaft sealing ring and a check ring are arranged between the inner wall of the lower shaft sleeve and the outer wall of the inner cylinder.

7. An ISD-based landing gear damper according to claim 1, wherein, The number and size of the grooves arranged on the upper flange of the brake sleeve are smaller than those of the grooves arranged on the lower flange.

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