A dual-chamber hydropneumatic shock absorber and aircraft landing gear

Abstract

This invention provides a dual-chamber hydraulic damper and an aircraft landing gear. The dual-chamber hydraulic damper includes an upper cam, a lower cam, an outer cylinder, a piston rod extending axially along the outer cylinder, an outer plunger, an inner plunger, and an end cap. One end of the outer plunger is located inside the outer cylinder and connected to it via the end cap, while the other end extends into the piston rod and connects to the lower cam. A partition is provided inside the outer plunger, dividing its interior into a first chamber and a second chamber. The inner plunger is placed in the first chamber and connected to the partition. An inflation valve is installed on the outer side of the end cap of the inner plunger. The second chamber and the interior of the inner plunger communicate to form a low-pressure chamber. The first chamber, separated by the inner plunger, forms a high-pressure chamber. A floating piston is fitted onto the inner plunger. This invention utilizes an internal plunger structure built into the plunger itself, with the filling channel VIII of the low-pressure chamber located at the top of the inner plunger, thus overcoming the shortcomings of existing technologies.

Description

Technical Field

[0001] This invention relates to the field of aircraft landing gear technology, and in particular to the design of a dual-chamber hydraulic damper and an aircraft landing gear. Background Technology

[0002] Dual-chamber hydrant-pneumatic buffers are important functional components in aircraft landing gear. Existing dual-chamber hydrant-pneumatic buffers are generally dual-chamber hydrant-pneumatic type, which have advantages such as high buffering efficiency, low landing overload, and good adaptability to runway surfaces. For example... Figure 17 As shown, the existing dual-chamber oil-gas buffer consists of four chambers: low-pressure air chamber I, main oil chamber V, return oil chamber II, and high-pressure air chamber VII. It mainly comprises an outer cylinder, plunger, piston rod, and floating piston.

[0003] The working principle of the aforementioned dual-chamber hydropneumatic damper is as follows: When the aircraft landing gear lands, the ground load is transmitted from the wheels and tires to the piston rod. The piston rod is pressed into the outer cylinder, reducing the volume of the main oil chamber V. Oil flows at high speed through the main oil hole IV on the plunger to the low-pressure air chamber I and through the return oil hole III on the plunger to the return oil chamber II, generating damping and dissipating energy. Simultaneously, the volume of the low-pressure air chamber I is compressed, absorbing energy. When the ground load further increases, and the pressure in the low-pressure air chamber I equals the pressure in the high-pressure air chamber VII, the floating piston in the high-pressure air chamber begins to work, compressing the high-pressure air chamber VII. Oil from the main oil chamber further flows at high speed through the main oil hole IV on the plunger to the low-pressure air chamber I and through the return oil hole III on the plunger to the return oil chamber II, generating damping and dissipating energy. Simultaneously, the volumes of the high-pressure and low-pressure air chambers further decrease, and the gas is compressed, absorbing energy and generating very high pressure. The above process is reversible when the piston rod extends. The high-pressure gas in high-pressure chamber VII and low-pressure chamber I releases energy and expands in volume. Oil in return chamber II flows at high speed back to main oil chamber V through return oil hole III, and oil in low-pressure chamber I flows at high speed back to main oil chamber V through main oil hole IV on the plunger, generating damping to further dissipate energy and prevent aircraft rebound. The high-speed flow of hydraulic oil inside the buffer through damping holes (main oil hole IV and return oil hole III) generates damping to dissipate the impact and jolt energy generated during landing or taxiing, reducing the impact load on the landing gear and aircraft fuselage and improving aircraft comfort during landing and taxiing.

[0004] like Figure 17 As shown, considering the needs of ground maintenance of aircraft landing gear, the filling channel IX of the high-pressure air chamber needs to be designed at the top of the outer cylinder or plunger. There are two existing technologies for the filling channel of the low-pressure air chamber. Option 1: The filling channel VIII of the low-pressure air chamber is designed on the side of the piston rod near the main oil chamber V. Option 2: The filling channel VIII of the low-pressure air chamber is designed at the bottom of the piston rod near the main oil chamber V and along the piston rod axis.

[0005] When using Option 1, since the piston rod is the main load-bearing component of the landing gear, and aircraft generally use ultra-high strength steel, the small hole or threaded hole in the filling channel VIII of the low-pressure air chamber is a weak point of ultra-high strength steel. The impact load during landing causes stress concentration around the hole, significantly affecting the fatigue life of the piston rod and severely reducing the service life of the buffer. Furthermore, the filling valve of the low-pressure air chamber is close to the ground, and on complex runways, there is a risk of high-speed flying debris impact, causing buffer leakage and rendering the buffer inoperable, potentially leading to aircraft destruction and loss of life.

[0006] When using Scheme 2, although this structural design avoids the stress concentration area of ​​the piston rod, the filling channel VIII of the low-pressure air chamber is often inside the piston rod cavity, making ground maintenance of the aircraft landing gear difficult. Summary of the Invention

[0007] The purpose of this invention is to provide a dual-chamber hydrophilic shock absorber and aircraft landing gear, which adopts an internal plunger structure built inside the plunger and sets the filling channel VIII of the low-pressure air chamber at the top of the internal plunger, thus overcoming the defects of the prior art.

[0008] The technical solution of the present invention is: a dual-chamber oil-gas type damper, comprising an upper cam, a lower cam, an outer cylinder, a piston rod that extends and retracts along the axial direction of the outer cylinder, an outer plunger, an inner plunger, and an end cap. One end of the outer plunger is located inside the outer cylinder and connected to the outer cylinder through the end cap. The other end of the outer plunger extends into the piston rod and is connected to the lower cam. The upper cam is connected to the piston rod, and the upper cam and the lower cam are adapted to each other.

[0009] The outer plunger is provided with a partition, which divides the interior of the outer plunger into a first cavity and a second cavity. The inner plunger is placed in the first cavity. One end of the inner plunger is connected to the partition, and the other end of the inner plunger passes through the partition and the end cap in sequence, and an inflation valve is installed on the outside of the end cap.

[0010] The second chamber of the outer plunger and the interior of the inner plunger are connected to form a low-pressure gas chamber, which is connected to the inflation valve; the first chamber separated by the inner plunger forms a high-pressure gas chamber, and a floating piston is fitted on the inner plunger. The gas pressure in the second chamber can push the floating piston to move up and down.

[0011] Preferably, one end of the outer cylinder is provided with a first flange with a hole, and the first flange is provided with an inner hole, and a plurality of first semi-circular holes are arranged circumferentially on the wall of the inner hole;

[0012] The end cap is provided with a second flange for fitting against one side of the first flange. One end of the outer plunger is provided with a third flange for fitting against the other side of the first flange. The second flange is provided with a plurality of first mounting holes in a circular pattern. The third flange is provided with a plurality of tenth through holes in a circular pattern. One end of the outer plunger is fitted into the inner hole, and a plurality of second semicircular holes are provided in a circular pattern on the axial end surface of the outer plunger extending into the inner hole. The second semicircular holes are aligned and connected with the tenth through holes. The first semicircular holes and the second semicircular holes correspond to each other and are radially joined in pairs to form a complete circular hole. The first mounting holes, the tenth through holes and the complete circular holes are aligned and a first fastener is installed inside them.

[0013] Preferably, the first fastener includes a bolt fitted into a first mounting hole, a tenth through hole, and a circular hole. The head of the bolt is in contact with the lower surface of the third flange or the upper surface of the second flange. A nut is installed on the bolt shank. A limiting plane is provided on the side of the bolt head near the outer plunger.

[0014] Preferably, the inner plunger includes a third body and a fourth flange at one end of the third body. The other end of the third body is provided with an external thread. The third body has a second through hole inside. The second through hole has a second threaded hole inside near the external thread. The inflation valve is installed on the second threaded hole. A hexagonal nut is connected to the external thread. The hexagonal nut fits against the end face of the end cap through a washer. The fourth flange has a plurality of third through holes in a circular pattern. The third through holes connect the second cavity and the high-pressure air cavity.

[0015] Preferably, the outer plunger has a fifth through hole communicating with the second cavity, and a plurality of sixth through holes are circumferentially arranged on the side wall forming the fifth through hole. An upper damping baffle and a lower damping baffle are installed in the fifth through hole. The lower cam is fitted onto the outside of the outer plunger. A second fastener for connecting the lower cam, the outer plunger and the lower damping baffle is installed in the sixth through hole.

[0016] Preferably, the dual-chamber oil-air damper further includes an oil needle, the lower end of which is installed inside the piston rod, and the upper end of which passes through the lower damping baffle and the upper damping baffle in sequence and extends into the second chamber, with the oil needle in clearance fit with the lower damping baffle and the upper damping baffle.

[0017] Preferably, the fifth through hole has a first inner bottom surface, the upper damping baffle has a seventh through hole inside, the seventh through hole is a countersunk hole with one large and one small hole, the larger hole has a second inner bottom surface, the lower damping baffle includes a cylindrical part with both ends through and a side plate surrounding one side of the cylindrical part, the side plate has a ninth through hole, and the side wall of the cylindrical part has an eighth through hole corresponding to the position of the sixth through hole;

[0018] The upper damping baffle is placed in the fifth through hole and abuts against the first inner bottom surface. A damping ring is installed in the seventh through hole. The lower surface of the upper damping baffle abuts against the upper surface of the side plate. The damping ring abuts between the second inner bottom surface and the side plate. The second fastener is installed after the sixth through hole, the eighth through hole and the corresponding hole on the lower cam are aligned.

[0019] Preferably, the end cap includes a first body for assembly inside the outer plunger and a plurality of first through holes penetrating the interior of the first body. Among the plurality of first through holes, one first through hole connects to the high-pressure air chamber and the inflation valve, another first through hole connects to the pressure sensor and the high-pressure air chamber, and the remaining first through holes connect to the oil filling valve and the interior of the piston rod.

[0020] Preferably, the first through hole includes an inclined section and a vertically arranged straight section. One end of the straight section is connected to the interior of the high-pressure air chamber or piston rod, and the other end of the straight section is connected to the inclined section. The inclined section is inclined upward and outward and is connected to the inflation valve or oil filling valve.

[0021] The present invention also provides an aircraft landing gear, including the above-described dual-chamber hydraulite buffer.

[0022] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0023] 1. An inner plunger is installed inside the outer plunger of the existing dual-chamber oil-gas buffer. The diameter of the through hole inside the inner plunger is larger than the outer diameter of the oil needle, avoiding the risk of collision between the oil needle and the floating piston, and solving the limitation on the structural design of the buffer caused by the relative position of the oil needle and the floating piston. After the high-pressure gas chamber starts working until the end of the buffer's compression stroke, the piston rod and oil needle compress rapidly, causing the gas pressure inside the high-pressure gas chamber to rise rapidly. However, at the same time, due to the limited volume of the high-pressure gas chamber, the floating piston moves slowly. If the filling parameters of the existing dual-chamber oil-gas buffer are unreasonable, there is a risk of collision between the oil needle and the floating piston. Alternatively, to avoid the risk of collision between the oil needle and the floating piston, the oil volume of the main oil chamber is increased, causing the oil needle structure to move downward. This results in a high oil-gas ratio, which reduces the buffer's buffering performance.

[0024] Second, the internal through-hole of the inner plunger connects to the low-pressure gas chamber, solving the problems of existing technologies where the filling channel design on the side of the piston rod near the main oil chamber poses a risk of reduced piston rod life, or where the design on the bottom of the piston rod near the main oil chamber along the piston rod axis causes difficulties in ground maintenance filling. The oil filling and air filling valves are designed on the top of the buffer, providing a relatively open ground maintenance space and making it more personnel-friendly for maintenance.

[0025] Third, the shaft-hole mating structure between the floating piston and the inner plunger solves the limitations of existing technologies regarding the low initial filling pressure of the high-pressure air chamber and the high strength requirements for the floating piston material. In existing technologies, the floating piston bears the entire pneumatic load of the high-pressure air chamber. If the filling pressure of the high-pressure air chamber is high, the load and stress on the floating piston are large, requiring high material strength. The shaft-hole mating structure between the floating piston and the inner plunger reduces the pneumatic load area of ​​the high-pressure air chamber, lowering the pneumatic load acting on the floating piston. This allows for a suitable increase in the initial filling pressure of the high-pressure air chamber, enabling the buffer to meet the requirements of larger aircraft landing gear with greater loads. Furthermore, the floating piston can be made of lightweight, lower-strength materials.

[0026] 4. The bolt rod passes through multiple first semi-circular holes around the first flange of the outer cylinder, multiple first mounting holes around the second flange of the end cap, and multiple tenth through holes and second semi-circular holes around the third flange of the outer plunger to form a shaft hole fit. The outer cylinder, outer plunger and end cap are fastened together by bolt connection and locking. With the cooperation of the upper and lower cam helical surfaces, the automatic centering function of the front landing gear buffer can be realized.

[0027] V. The outer cylinder, outer plunger, and end cap adopt a bolted, separate structural design. Existing technologies typically use a threaded connection structure similar to the inner plunger and high-pressure end cap in this embodiment to connect the outer plunger and outer cylinder. These structures are semi-enclosed with a large length-to-diameter ratio, posing challenges for deep-hole machining. In this invention, the outer cylinder, outer plunger, and high-pressure end cap adopt a bolted, separate structural design. The inner cavities of the outer cylinder and outer plunger are open, solving the problem of requiring deep or ultra-deep-hole machining for the semi-enclosed, high length-to-diameter ratio structures of existing outer cylinders and outer plungers, thus reducing the difficulty of part machining.

[0028] VI. The damping structure adopts a bolted connection design. In existing technologies, the lower damping baffle has threads on its cylindrical part, and the outer plunger has threads. The lower damping baffle and the outer plunger are connected by an inner and outer sleeve using a threaded structure. Under the repeated impact of the oil damping inside the buffer, there is a problem of thread loosening. Existing technologies generally use a keyed fit structure between the lower cam and the outer plunger, which is complex in terms of processing and installation. This invention uses a second fastener to fasten the outer plunger, upper damping baffle, lower damping baffle, and lower cam together. The structure is simple and can achieve a reliable connection between the lower cam and the damping structure, avoiding the shortcomings of existing technologies. At the same time, the bolted connection structure can transmit the centering torque generated by the mass of the lower part of the buffer, thereby realizing the automatic centering function of the nose landing gear. Attached Figure Description

[0029] Figure 1 A schematic diagram of the internal structure of the dual-cavity oil-gas buffer provided by the present invention;

[0030] Figure 2 For along Figure 1AA section view diagram;

[0031] Figure 3 A partial schematic diagram of the dual-cavity oil-gas buffer provided by the present invention;

[0032] Figure 4 This is a schematic diagram of the outer cylinder structure;

[0033] Figure 5 For along Figure 4 BB cross-sectional diagram;

[0034] Figure 6 This is a schematic diagram of the end cap structure;

[0035] Figure 7 This is a half-sectional view of the end cap;

[0036] Figure 8 This is a schematic diagram of the external plunger structure;

[0037] Figure 9 For along Figure 8 CC cross-sectional view;

[0038] Figure 10 This is a schematic diagram of the internal plunger structure;

[0039] Figure 11 For along Figure 10 DD cross-sectional view;

[0040] Figure 12 This is a schematic diagram of the structure of a floating piston;

[0041] Figure 13 This is a schematic cross-sectional view of the upper damping baffle.

[0042] Figure 14 This is a schematic diagram of the lower damping baffle.

[0043] Figure 15 This is a schematic diagram of the bolt in the first fastener;

[0044] Figure 16 A schematic diagram of the dual-cavity oil-gas buffer provided by the present invention;

[0045] Figure 17 This is a schematic diagram of an existing dual-chamber oil-gas buffer.

[0046] In the attached diagram: Ⅰ, Low-pressure gas chamber; Ⅱ, Oil return chamber; Ⅲ, Oil return hole; Ⅳ, Main oil hole; Ⅴ, Main oil chamber; Ⅵ, Gas hole; Ⅶ, High-pressure gas chamber; Ⅷ, Low-pressure gas chamber filling channel; Ⅸ, High-pressure gas chamber filling channel;

[0047] 1. Outer cylinder; 101. First flange; 102. First semi-circular hole; 103. Inner hole; 104. First surface; 105. Second surface; 2. End cap; 21. Second flange; 22. First mounting hole; 23. Boss; 24. First through hole; 241. Inclined section; 242. Straight section; 25. First threaded hole; 26. Second mounting hole; 27. Annular groove; 28. First body; 3. Outer plunger; 31. Second body; 32. Third flange; 33. Third surface; 34. Partition; 35. First cavity; 36. Countersunk hole; 37. Second cavity; 38. Fifth through hole; 39. Sixth through hole; 310. Tenth through hole; 311. Second semi-circular hole; 312. First inner bottom surface; 4. Inner plunger; 41. Third body; 42. Fourth flange; 43. Second threaded hole; 44. Second through hole; 45. External thread; 46. Third through hole; 5. Floating piston; 51. Fourth through hole; 6. Upper support; 7. Piston rod; 8. Upper cam; 9. Lower cam; 10. Expansion ring; 11. Upper damping baffle; 111. Seventh through hole; 112. Second inner bottom surface; 12. Lower damping baffle; 121. Side plate; 122. Cylindrical part; 123. Ninth through hole; 124. Eighth through hole; 13. Lower support; 14. Oil needle; 15. Sealing ring; 16. Second fastener; 17. Oil-filled valve; 18. Air-filled valve; 20. Gasket; 29. ​​Hex nut; 210. Bolt; 2101. Limiting plane; 2102. Polished rod part; 211. Pressure sensor. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0049] like Figure 1 , Figure 3 As shown, the dual-chamber oil-pneumatic buffer provided in this embodiment includes an outer cylinder 1, an end cap 2, an outer plunger 3, an inner plunger 4, a floating piston 5, an upper support 6, a piston rod 7, an upper cam 8, a lower cam 9, an expansion ring 10, an upper damping baffle 11, a lower damping baffle 12, a lower support 13, an oil needle 14, a sealing ring 15, a second fastener 16, an oil filling valve 17, an air filling valve 18, a hexagonal nut 29, a first fastener, a gasket 20, and a pressure sensor 211.

[0050] like Figure 3 , Figure 4 , Figure 5As shown, the upper inner wall of the outer cylinder 1 is provided with a first flange 101, and the first flange 101 is provided with an inner hole 103. The inner hole 103 is provided with a plurality of first semi-circular holes 102 arranged in a circular pattern on the hole wall. The upper end of the first flange 101 is provided with a first surface 104, and the lower end is provided with a second surface 105.

[0051] like Figure 6 , Figure 7 As shown, the end cap 2 includes a first body 28 and a second flange 21 located at one end of the first body 28. The second flange 21 has a plurality of first mounting holes 22 arranged circumferentially. The first body 28 has a through second mounting hole 26 inside, which is used to insert the upper end of the inner plunger 4 (e.g., ...). Figure 1 (As shown). The outer wall of the first body 28 is provided with a plurality of annular grooves 27, and the annular grooves 27 are used to install sealing rings 15 that contact the inner wall of the outer plunger 3.

[0052] The upper surface of the second flange 21 is provided with three bosses 23, and the bosses 23 are provided with first threaded holes 25 for respectively installing the air valve 18 and the oil valve 17 (e.g. Figure 3 As shown). Figure 2 , Figure 6 As shown, the first body 28 has three first through holes 24 inside. One first through hole 24 connects the high-pressure air chamber VII and the inflation valve 18, another first through hole 24 connects the pressure sensor 211 and the high-pressure air chamber VII, and the remaining first through hole 24 connects the oil filling valve 17 and the interior of the piston rod 7. Figure 7 As shown, the first through hole 24 includes an inclined section 241 and a vertically arranged straight section 242. One end of the straight section 242 is connected to the interior of the high-pressure air chamber VII or the piston rod 7, and the other end of the straight section 242 is connected to the inclined section 241. The inclined section 241 is inclined upward and outward and is connected to the inflation valve 18 or the oil filling valve 17.

[0053] like Figure 8 , Figure 9 As shown, the outer plunger 3 includes a second body 31. One end of the second body 31 is provided with a third flange 32 (a distance from the end is formed for providing a second semi-circular hole 311 and for forming a shaft end that is inserted into the outer cylinder 1). The third flange 32 is provided with a plurality of tenth through holes 310 circumferentially. The outer plunger 3 is assembled on the shaft end of the inner hole 103, which is provided with a plurality of second semi-circular holes 311 circumferentially (e.g., ... Figure 3 As shown). The tenth through hole 310 and the second semicircular hole 311 are aligned and connected (as shown). Figure 8 As shown), multiple second semicircular holes 311 correspond one-to-one with the first semicircular holes 102 on the inner hole 103, and each pair radially connects to form a complete circular hole.

[0054] like Figure 9 As shown, the third flange 32 has a third surface 33. During installation, the third surface 33 is in contact with the second surface 105, and the lower surface of the second flange 21 is in contact with the first surface 104. The first mounting hole 22, the tenth through hole 310, and the circular hole are aligned one-to-one, and a first fastener (such as...) is installed inside them. Figure 1 As shown). Figure 1 As shown, the second flange 21 and the third flange 32 are sandwiched between the upper and lower sides of the first flange 101.

[0055] The first fastener includes a bolt 210 fitted into the first mounting hole 22, the tenth through hole 310, and the full-circular hole. The smooth shank 2102 of the bolt 210 engages with the second semi-circular hole 311 and the first semi-circular hole 102. The head of the bolt 210 is in contact with the lower surface of the third flange 32. A nut is mounted on the bolt 210. A limiting plane 2101 (e.g., ...) is provided on the side of the bolt head near the outer plunger 3. Figure 2 , Figure 15 As shown in the figure, the limiting plane 2101 can prevent the bolt 210 from loosening.

[0056] like Figure 9 As shown, the outer plunger 3 has a partition 34 inside, which divides the interior of the outer plunger 3 into a first cavity 35 and a second cavity 37. The second body 31 has a fifth through hole 38 at the end away from the third flange 32, and a first inner bottom surface 312 is formed between the fifth through hole 38 and the second cavity 37. Multiple sixth through holes 39 are arranged circumferentially on the sidewall forming the fifth through hole 38. The partition 34 has countersunk holes 36 of different sizes, with the larger end of the countersunk hole 36 facing the second cavity 37 and the smaller end facing the first cavity 35. All cavities and holes inside the outer plunger 3 are interconnected.

[0057] like Figure 10 , Figure 11 As shown, the inner plunger 4 includes a third body 41, one end of which has a fourth flange 42, and the other end has an external thread 45. The interior of the third body 41 has a stepped second through hole 44, the diameter of which gradually decreases from the fourth flange 42 towards the external thread 45. A second threaded hole 43 is formed at the end of the second through hole 44 near the external thread 45, and this threaded hole 43 is used to install the inflation valve 18. The fourth flange 42 has a plurality of circumferentially arranged third through holes 46.

[0058] like Figure 1As shown, the inner plunger 4 is placed in the first cavity 35 of the outer plunger 3, and the fourth flange 42 is placed in the large hole of the countersunk hole 36. The end of the inner plunger 4 away from the fourth flange 42 extends from the second mounting hole 26 of the end cover 2, and a hexagonal nut 29 is installed on the shaft end with external threads 45. The hexagonal nut 29 abuts against the end face of the end cover 2 through a washer 20. A sealing ring 15 is provided between the inner plunger 4 and the second mounting hole 26. The high-pressure load of the internal gas pressure of the high-pressure gas chamber VII acting on the end cover 2 is transmitted to the partition 34 through the third body 41 of the inner plunger 4, which can reduce the load of the first fastener from the internal gas pressure of the high-pressure gas chamber VII. The fourth flange 42 of the inner plunger 4 is installed in the countersunk hole 36 with a certain gap. When the coaxiality of the third body 41 of the inner plunger 4 and the second mounting hole 26 of the end cover 2 is poor, the problem of the sealing ring 15 being difficult to install and easily damaged is solved.

[0059] like Figure 1 , Figure 12 As shown, the floating piston 5 has a fourth through hole 51 for the inner plunger 4 to pass through. Sealing rings 15 are provided between the floating piston 5 and the inner plunger 4, and between the floating piston 5 and the outer plunger 3.

[0060] The second cavity 37 of the outer plunger 3 and the second through hole 44 of the inner plunger 4 communicate to form a low-pressure gas chamber I, which is connected to the inflation valve 18. The first cavity 35, separated by the inner plunger 4, forms a high-pressure gas chamber VII, in which the floating piston 5 is located. The third through hole 46 on the fourth flange 42 and the small hole of the countersunk hole 36 form a channel, which is a gas hole VI, connecting the low-pressure gas chamber I and the high-pressure gas chamber VII, allowing the gas pressure in the second cavity 37 to push the floating piston 5 up and down.

[0061] like Figure 13 As shown, the upper damping baffle 11 is provided with a seventh through hole 111, which is a countersunk hole with one large and one small hole, and the larger hole has a second inner bottom surface 112.

[0062] like Figure 14 As shown, the lower damping baffle 12 includes a cylindrical portion 122 extending through both ends and a side plate 121 surrounding one side of the cylindrical portion 122. A ninth through hole 123 is provided on the side plate 121, and an eighth through hole 124 corresponding to the position of the sixth through hole 39 is provided on the side wall of the cylindrical portion 122.

[0063] like Figure 1As shown, the upper damping baffle 11 is placed in the fifth through hole 38 and abuts against the first inner bottom surface 312. A damping ring 19 is installed in the seventh through hole 111. The lower surface of the upper damping baffle 11 abuts against the upper surface of the side plate 121. The damping ring 19 abuts between the second inner bottom surface 112 and the side plate 121. After the sixth through hole 39, the eighth through hole 124 and the corresponding holes on the lower cam 9 are aligned, the second fastener 16 (bolt, washer, nut) is installed to transmit the centering torque generated by the lower mass of the dual-cavity oil-gas buffer to the outer plunger 3. The washer is an arc-shaped washer, whose arc surface mates with the ninth through hole 123 of the lower damping baffle 12.

[0064] like Figure 1 As shown, sealing rings 15 are provided between the upper cam 8, the outer plunger 3, and the piston rod 7. The upper cam 8 is connected to the piston rod 7. The helical drive structure of the upper cam 8 and the lower cam 9 is the same as that of the existing patent CN202481305U, and will not be described again here.

[0065] like Figure 1 , Figure 16 As shown, a return oil chamber II is formed between the lower cam 9 and the piston rod 7. An expansion ring 10 is fitted onto the lower cam 9, and the outer surface of the expansion ring 10 contacts the inner wall of the piston rod 7. An oil return hole III is provided on the lower cam 9, and the oil return hole III is located below the expansion ring 10.

[0066] The piston rod 7 has a main oil chamber V inside, and the oil filling valve 17 is connected to the main oil chamber V.

[0067] The oil needle 14 is located in the main oil chamber V, with its lower end installed inside the piston rod 7. A sealing ring 15 is provided between the oil needle 14 and the inner wall of the piston rod 7 at this location. The upper end of the oil needle 14 passes through the ninth through hole 123 of the lower damping baffle 12 and the seventh through hole 111 of the upper damping baffle 11 in sequence and extends into the second chamber 37. The oil needle 14 is clearance-fitted with the ninth through hole 123 and the seventh through hole 111, and this clearance forms the main oil hole IV.

[0068] The upper support 6 and the lower support 13 are both mounted on the piston rod 7, which guides the compression and extension of the piston rod 7 and jointly transmits the ground load to the outer cylinder 1.

[0069] When the dual-chamber hydrophilic damper provided by this invention is applied to the nose landing gear, during takeoff, the piston rod 7 extends under the pressure of the internal air chambers of the dual-chamber hydrophilic damper on the nose landing gear strut, causing the upper cam 8 and lower cam 9 to engage on their helical surfaces. The lower part of the dual-chamber hydrophilic damper (such as the piston rod 7, the wheel, or the tire) automatically returns to center. During the centering process, the centering torque generated by the mass of the lower part of the dual-chamber hydrophilic damper is transmitted to the outer plunger 3 through the upper cam 8 and lower cam 9, and then transmitted to the first flange 101 of the outer cylinder 1 through the first fastener fastened to the outer plunger 3, thereby realizing the automatic centering function of the nose landing gear.

[0070] In another embodiment, the third flange 32 can be moved to the end of the second body 31, the second semicircular hole 311 disappears, and only the tenth through hole 310 is provided. The first semicircular hole 102 is a threaded hole. The side of the third flange 32 away from the third surface 33 is attached to the first surface 104, the lower surface of the second flange 21 on the end cap 2 is attached to the third surface 33, and the bolt 210 is fixedly inserted from top to bottom into the first mounting hole 22, the tenth mounting hole 310 and the threaded hole of the first semicircular hole 102, with the head of the bolt 210 attached to the upper surface of the second flange 21.

[0071] like Figure 16 As shown, the high-pressure gas chamber filling channel IX is located at the top of the dual-chamber oil-gas buffer and communicates with the high-pressure gas chamber VII. The low-pressure gas chamber filling channel is located at the top of the dual-chamber oil-gas buffer and communicates with the low-pressure gas chamber I. The dual-chamber oil-gas buffer of the present invention achieves this by incorporating an inner plunger structure inside the plunger, and placing the low-pressure gas chamber filling channel VIII at the top of the inner plunger, effectively solving the technical problems existing in the prior art when using schemes one and two.

[0072] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A dual-chamber oil-gas type damper, comprising an upper cam (8), a lower cam (9), an outer cylinder (1), and a piston rod (7) that extends and retracts axially along the outer cylinder (1), characterized in that, It also includes an outer plunger (3), an inner plunger (4) and an end cap (2). One end of the outer plunger (3) is located inside the outer cylinder (1) and connected to the outer cylinder (1) through the end cap (2). The other end of the outer plunger (3) extends into the piston rod (7) and is connected to the lower cam (9). The upper cam (8) is connected to the piston rod (7) and is adapted to the lower cam (9). The outer plunger (3) is provided with a partition (34), which divides the interior of the outer plunger (3) into a first cavity (35) and a second cavity (37). The inner plunger (4) is placed in the first cavity (35). One end of the inner plunger (4) is connected to the partition (34), and the other end of the inner plunger (4) passes through the partition (34) and the end cap (2) in sequence, and an inflation valve (18) is installed on the outside of the end cap (2). The second chamber (37) of the outer plunger (3) and the interior of the inner plunger (4) are connected to form a low-pressure gas chamber (I), which is connected to the inflation valve (18); the first chamber (35) separated by the inner plunger (4) forms a high-pressure gas chamber (VII), and a floating piston (5) is fitted on the inner plunger (4). The gas pressure in the second chamber (37) can push the floating piston (5) to move up and down; The inner plunger (4) includes a third body (41) and a fourth flange (42) at one end of the third body (41). The other end of the third body (41) is provided with an external thread (45). The third body (41) is provided with a second through hole (44). The second through hole (44) is provided with a second threaded hole (43) near the external thread (45). The inflation valve (18) is installed on the second threaded hole (43). A hexagonal nut (29) is connected to the external thread (45). The hexagonal nut (29) is in contact with the end face of the end cap (2) through a washer (20). The fourth flange (42) is provided with a plurality of third through holes (46) in a circular pattern. The third through holes (46) connect the second cavity (37) and the high-pressure air cavity (VII). The outer plunger (3) is provided with a fifth through hole (38) communicating with the second cavity (37). The side wall forming the fifth through hole (38) is provided with a plurality of sixth through holes (39) in a circular pattern. An upper damping baffle (11) and a lower damping baffle (12) are installed in the fifth through hole (38). The lower cam (9) is fitted onto the outside of the outer plunger (3). A second fastener (16) for connecting the lower cam (9), the outer plunger (3) and the lower damping baffle (12) is installed in the sixth through hole (39).

2. The dual-chamber oil-gas buffer according to claim 1, characterized in that, The outer cylinder (1) has a first flange (101) with a hole at one end. The first flange (101) has an inner hole (103) inside. Multiple first semi-circular holes (102) are arranged circumferentially on the wall of the inner hole (103). The end cap (2) is provided with a second flange (21) for fitting against one side surface of the first flange (101). One end of the outer plunger (3) is provided with a third flange (32) for fitting against the other side surface of the first flange (101). The second flange (21) is provided with a plurality of first mounting holes (22) in a circular pattern. The third flange (32) is provided with a plurality of tenth through holes (310) in a circular pattern. One end of the outer plunger (3) is fitted into the inner hole (103), and a plurality of second semi-circular holes (311) are provided in a circular pattern on the axial end surface of the outer plunger (3) extending into the inner hole (103). The second semi-circular holes (311) are aligned and connected with the tenth through holes (310). The first semi-circular holes (102) and the second semi-circular holes (311) correspond to each other and are radially connected in pairs to form a complete circular hole. The first mounting holes (22), the tenth through holes (310) and the complete circular holes are aligned and a first fastener is installed inside them.

3. The dual-chamber oil-gas buffer according to claim 2, characterized in that, The first fastener includes a bolt (210) fitted into the first mounting hole (22), the tenth through hole (310) and the round hole. The head of the bolt (210) is in contact with the lower surface of the third flange (32) or the upper surface of the second flange (21). A nut is installed on the shank of the bolt (210). A limiting plane (2101) is provided on the side of the head of the bolt (210) near the outer plunger (3).

4. The dual-chamber oil-gas buffer according to claim 1, characterized in that, It also includes an oil needle (14), the lower end of which is installed inside the piston rod (7), and the upper end of which passes through the lower damping baffle (12) and the upper damping baffle (11) in sequence and extends into the second cavity (37), and the oil needle (14) is in clearance fit with the lower damping baffle (12) and the upper damping baffle (11).

5. The dual-chamber oil-gas buffer according to claim 1, characterized in that, The fifth through hole (38) has a first inner bottom surface (312). The upper damping baffle (11) has a seventh through hole (111) inside. The seventh through hole (111) is a countersunk hole with one large and one small hole. The larger hole has a second inner bottom surface (112). The lower damping baffle (12) includes a cylindrical part (122) that extends through both ends and a side plate (121) that surrounds one side of the cylindrical part (122). A ninth through hole (123) is opened on the side plate (121). An eighth through hole (124) corresponding to the position of the sixth through hole (39) is opened on the side wall of the cylindrical part (122). The upper damping baffle (11) is placed in the fifth through hole (38) and abuts against the first inner bottom surface (312). A damping ring (19) is installed in the seventh through hole (111). The lower surface of the upper damping baffle (11) abuts against the upper surface of the side plate (121). The damping ring (19) abuts between the second inner bottom surface (112) and the side plate (121). The second fastener (16) is installed after the corresponding holes on the sixth through hole (39), the eighth through hole (124) and the lower cam (9) are aligned.

6. The dual-chamber oil-gas buffer according to claim 1, characterized in that, The end cap (2) includes a first body (28) for assembly inside the outer plunger (3) and a plurality of first through holes (24) penetrating inside the first body (28). Among the plurality of first through holes (24), one first through hole (24) connects the high-pressure air chamber (VII) and the inflation valve (18), another first through hole (24) connects the pressure sensor (211) and the high-pressure air chamber (VII), and the remaining first through holes (24) connect the oil filling valve (17) and the interior of the piston rod (7).

7. The dual-chamber oil-gas buffer according to claim 6, characterized in that, The first through hole (24) includes an inclined section (241) and a vertically arranged straight section (242). One end of the straight section (242) is connected to the interior of the high-pressure air chamber (VII) or the piston rod (7), and the other end of the straight section (242) is connected to the inclined section (241). The inclined section (241) is inclined upward and outward and is connected to the air filling valve (18) or the oil filling valve (17).

8. An aircraft landing gear, characterized in that, Including the dual-chamber oil-gas buffer as described in any one of claims 1-7.

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