Undercarriage buffer

Abstract

The invention provides an undercarriage buffer. The undercarriage buffer comprises an outer cylinder and a piston rod stretching out and drawing back in the outer cylinder, the piston rod is provided with an inner cavity, a plunger is arranged in the outer cylinder, one end of the plunger extends into the inner cavity of the piston rod, the plunger divides the outer cylinder into a buffer cavity and a non-functional cavity, and one end of the piston rod is located in the buffer cavity; an upper end seal for isolating the non-functional cavity from the atmosphere is arranged in the outer cylinder; an oil limiting pipe seal used for injecting oil into the buffering cavity and used for stopping rotation of the plunger is arranged between the plunger and the outer barrel. The plunger is provided with a first static sealing structure used for isolating the buffering cavity from the non-functional cavity. And a lower end seal for isolating the buffer cavity from the atmosphere is arranged between the piston rod and the outer cylinder. The sealing structure surface is prevented from rotating relative to the outer cylinder, the structural stability of the sealing surface is improved, and then the sealing reliability is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft landing gear, and in particular to a landing gear buffer. Background Art

[0002] The landing gear is one of the most important components of an aircraft, playing a vital role in the safety of the aircraft during takeoff and landing. The effective operation of the landing gear is inseparable from the good sealing performance of the buffer.

[0003] Existing shock absorbers only have functional cavities, without non-functional cavities (relief cavities), and are externally sealed at both ends. Under the complex operating conditions of landing gear installation, the seal interface between the components and the outer tube must account for the effects of external ground loads and internal shock absorber pressure. This often results in relative rotation between the seal surface and the outer tube. Any rotation of the seal surface relative to the outer tube will affect the shock absorber seal. Summary of the Invention

[0004] The object of the present invention is to provide a landing gear buffer, which prevents the sealing structure surface from rotating relative to the outer tube, improves the structural stability of the sealing surface, and further enhances the sealing reliability.

[0005] The technical solution of the present invention is: a landing gear buffer, comprising an outer tube and a piston rod telescopically extended in the outer tube, the piston rod having an inner cavity, a plunger provided in the outer tube, one end of the plunger extending into the inner cavity of the piston rod, the plunger dividing the outer tube into a buffer cavity and a non-functional cavity, one end of the piston rod being located in the buffer cavity; an upper end seal for isolating the non-functional cavity from the atmosphere is provided in the outer tube; an oil limiting pipe seal for injecting oil into the buffer cavity and for stopping the plunger from rotating is provided between the plunger and the outer tube; a first static sealing structure for isolating the buffer cavity from the non-functional cavity is provided on the plunger; a lower end seal for isolating the buffer cavity from the atmosphere is provided between the piston rod and the outer tube.

[0006] Preferably, the upper end seal includes a stop bolt provided on the side of the outer cylinder close to the non-functional cavity and an end cover provided on the side of the outer cylinder away from the non-functional cavity. The end cover is connected to the stop bolt and is fixed by a nut. O-rings are provided between the end cover and the outer cylinder and between the end cover and the stop bolt.

[0007] Preferably, the stop bolt includes a connecting plate and a connecting shaft connected to the middle of one side of the connecting plate, the end of the connecting plate is provided with a step for clamping on the outer cylinder, the end cover and the O-ring are both mounted on the connecting shaft, and the nut is connected to the connecting shaft.

[0008] Preferably, the oil limiting tube seal includes an oil nozzle mounting seat inserted into the outer tube and the plunger at the same time at right angles to the axis of the piston rod, an oil limiting tube is provided in the plunger, a first oil circuit is provided in the oil nozzle mounting seat, a second oil circuit is provided in the oil limiting tube, and the second oil circuit connects the first oil circuit and the buffer chamber; a second static sealing structure is provided between the oil nozzle mounting seat and the outer tube and between the oil limiting tube and the plunger.

[0009] Preferably, the oil limiting tube includes a first shaft portion and a second shaft portion vertically connected to one end of the first shaft portion, the second oil circuit is arranged in the first shaft portion and the second shaft portion, the first shaft portion is provided with an interface that passes through the side wall of the first shaft portion and is connected to the second oil circuit, and the second oil circuit passes through one side of the second shaft portion to form a hole plane; the second static sealing structure is provided on the first shaft portion; the first shaft portion is inserted into the plunger, the end of the oil nozzle mounting seat extends into the interface, the second shaft portion is located outside the plunger, and the hole plane is sealed toward the upper end.

[0010] Preferably, the lower end seal includes a lower sleeve assembly sleeved between the outer tube and the piston rod, the inner wall of the lower sleeve assembly is provided with a dynamic sealing structure and a support ring in contact with the piston rod, and the outer wall of the lower sleeve assembly is provided with a third static sealing structure in contact with the outer tube.

[0011] Preferably, the dynamic sealing structure, the support ring and the third static sealing structure are arranged in plurality in the axial direction of the lower sleeve assembly, and one dynamic sealing structure is arranged between two adjacent support rings.

[0012] Preferably, a retaining ring is mounted on the piston rod, a limiting ring abutting against the retaining ring is mounted on the end of the lower sleeve assembly, and the retaining ring is connected to the lower sleeve assembly via screws.

[0013] Preferably, the limiting ring is a three-section ring structure.

[0014] Preferably, an oil needle is provided in the inner cavity of the piston rod, one end of the oil needle is provided with an O-ring in contact with the inner wall of the piston rod, and the other end of the oil needle is provided with a damping ring, which is arranged close to the plunger; an upper support sleeve is provided on the outside of the end of the piston rod provided with the damping ring, and the upper support sleeve is in sliding contact with the outer cylinder.

[0015] Compared with the related art, the present invention has the following beneficial effects: First, the present invention adopts three sealing methods: upper end seal, oil limit pipe seal and lower end seal. The upper end seal is used to isolate the non-functional cavity from the atmosphere. The first static seal structure is provided in the middle to isolate the buffer cavity from the non-functional cavity. The lower end seal is used to isolate the buffer cavity from the atmosphere. By eliminating the thread structure at the outer cylinder seal, the manufacturability of high-precision machining of the outer cylinder sealing surface is improved, thereby reducing the sealing failure caused by the roughness of the sealing surface and the difficulty in ensuring the form and position tolerance. Second, the oil limiting pipe seal designed by the present invention passes through the plunger and the oil injection nozzle mounting seat at the same time. In addition to filling the buffer chamber with oil, it can also stop the plunger from rotating, avoiding the problem of torsion of the first static sealing structure caused by the rotation trend, improving the stability of the first static sealing structure, and thus enhancing the reliability of the seal. 3. The present invention improves the economy and reliability of the product. In addition, the oil-fixing structure of the buffer is convenient for field use and maintenance. Accurate oil fixing can be completed without returning to the factory, which greatly reduces the use and maintenance cost of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic cross-sectional view of a landing gear buffer provided by the present invention; Figure 2 for Figure 1 A is an enlarged schematic diagram; Figure 3 for Figure 1 A magnified schematic diagram of point B in FIG. Figure 4 For the Figure 1 The CC cross-sectional view in FIG. Figure 5 For the Figure 1 DD cross-sectional diagram in; Figure 6 Schematic diagram of the structure of the stop bolt; Figure 7 Schematic diagram of the structure of the lower end seal; Figure 8 Schematic diagram of the structure of the limit ring; Figure 9 This is a cross-sectional schematic diagram of the oil limiting pipe from a first viewing angle; Figure 10 This is a structural diagram of the oil limiting pipe from the second perspective.

[0017] In the figure: 1, outer cylinder; 101, buffer chamber; 102, non-functional chamber; 2, stop bolt; 201, connecting plate; 202, connecting shaft; 203, step; 3, O-ring; 4, nut; 5, end cover; 6, lower sleeve assembly; 7, limit ring; 8, retaining ring; 9, piston rod; 10, dust ring; 11, screw; 12, upper support sleeve; 13, damping ring; 14, plunger; 141, process hole; 15, first static sealing structure; 16, oil Needle; 17, inflation valve; 18, oiling nozzle mounting seat; 181, first oil circuit; 19, second static sealing structure; 20, oil limiting pipe; 2001, interface; 2002, groove; 2003, hole plane; 2004, second oil circuit; 2005, first shaft portion; 2006, second shaft portion; 21, third static sealing structure; 22, dynamic sealing structure; 23, support ring; 24, upper end seal; 25, oil limiting pipe seal; 26, lower end seal. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appear below merely to indicate the directions of upper, lower, left, and right in the accompanying drawings and do not limit the structure.

[0019] like Figure 1 As shown, the landing gear buffer provided in this embodiment includes an outer tube 1 and a piston rod 9 that is retracted within the outer tube 1. The piston rod 9 has an inner cavity, and a plunger 14 is provided within the outer tube 1. One end of the plunger 14 extends into the inner cavity of the piston rod 9. The plunger 14 divides the interior of the outer tube 1 into a buffer cavity 101 and a non-functional cavity 102. During use, the non-functional cavity 102 faces upward. The top of the plunger 14 is provided with a process hole 141 to facilitate installation of the plunger 14.

[0020] One end of the piston rod 9 is located in the buffer chamber 101; an upper end seal 24 is provided in the outer tube 1 for isolating the non-functional chamber 102 from the atmosphere; an oil limiting pipe seal 25 is provided between the plunger 14 and the outer tube 1 for injecting oil into the buffer chamber 101 and for stopping the plunger 14 from rotating; a first static sealing structure 15 is provided on the plunger 14 for isolating the buffer chamber 101 from the non-functional chamber 102; a lower end seal 26 is provided between the piston rod 9 and the outer tube 1 for isolating the buffer chamber 101 from the atmosphere.

[0021] like Figure 1 、 Figure 3As shown, the upper end seal 24 is a static seal that seals the non-functional cavity 102 (air cavity) and the outside atmosphere. The upper end seal 24 includes a stop bolt 2, an O-ring 3, a nut 4, and an end cap 5. The stop bolt 2 is clamped on the side of the outer cylinder 1 close to the non-functional cavity 102, and the end cap 5 is clamped on the side of the outer cylinder 1 away from the non-functional cavity 102. Figure 6 As shown, the stopper bolt 2 includes a connecting plate 201 and a connecting shaft 202 connected to the middle of one side of the connecting plate 201. The end of the connecting plate 201 is provided with a step 203 for engaging with the outer cylinder 1. The end cap 5 is connected to the connecting shaft 202 of the stopper bolt 2 and secured with a nut 4. O-rings 3 are provided between the end cap 5 and the outer cylinder 1, and between the end cap 5 and the connecting shaft 202 of the stopper bolt 2. The connecting plate 201 is manufactured by milling.

[0022] like Figure 1 、 Figure 4 As shown, the outer cylinder 1 seals the buffer chamber 101 and the non-functional chamber 102 via a first static sealing structure 15 and an oil limiting pipe seal 25. Two first static sealing structures 15 are provided axially on the plunger 14 and abut against the inner wall of the outer cylinder 1.

[0023] The oil limiting pipe seal 25 includes an oil injection nozzle mounting seat 18 that is inserted into the outer cylinder 1 and the plunger 14 at the same time perpendicular to the axis of the piston rod 9. Two second static sealing structures 19 are provided between the oil injection nozzle mounting seat 18 and the outer cylinder 1. A first oil passage 181 is provided in the oil injection nozzle mounting seat 18. The plunger 14 is provided with an oil limiting pipe 20. Figure 9 、 Figure 10 As shown, the oil limiting tube 20 includes a first shaft portion 2005 and a second shaft portion 2006 perpendicularly connected to one end of the first shaft portion 2005. A second oil passage 2004 is provided on the axis of the first shaft portion 2005 and the second shaft portion 2006. The first shaft portion 2005 is provided with an interface 2001 that passes through the side wall of the first shaft portion 2005 and communicates with the second oil passage 2004. The second oil passage 2004 passes through one side of the second shaft portion 2006 to form a hole plane 2003. The first shaft portion 2005 has a groove 2002, and a second static seal structure 19 (such as the second static seal structure 19) is embedded in the groove 2002 and abuts against the plunger 14. Figure 4 The second static sealing structure 19 may be a sealing ring.

[0024] like Figure 1 、 Figure 4As shown, the first shaft portion 2005 is inserted into the plunger 14, and the distal end of the oil nozzle mounting base 18 extends into the interface 2001 to secure the oil limiting tube 20 in place within the plunger 14. The first oil passage 181, the second oil passage 2004, and the buffer chamber 101 are interconnected. The second shaft portion 2006 is located outside the plunger 14, with the bore surface 2003 facing the upper seal 24. The oil nozzle mounting base 18 is mounted with an inflation valve 17. The inflation valve 17 is supplied with a built-in sealing ring.

[0025] To fill the buffer, remove the charging valve 17, position the buffer in a vertical position (with the end with the upper seal 24 facing upward), and connect the oil filling pipeline to the oil filling nozzle mounting 18. Oil is then added to the buffer cavity 101 through the interconnected oil filling pipeline, first oil passage 181, and second oil passage 2004. When the oil level reaches the hole plane 2003 on the oil limiting tube 20, further oil injection is stopped. At this point, the oil level in the buffer cavity 101 has reached the design requirement, achieving automatic oil level monitoring.

[0026] like Figure 1 、 Figure 2 、 Figure 7 As shown, the lower end seal 26 includes a lower sleeve assembly 6 that is sleeved between the outer tube 1 and the piston rod 9. A dynamic seal structure 22 and a support ring 23 are provided on the inner wall of the lower sleeve assembly 6, which contacts the piston rod 9. Multiple dynamic seal structures 22 and support rings 23 are arranged axially along the lower sleeve assembly 6, with one dynamic seal structure 22 positioned between two adjacent support rings 23.

[0027] A third static sealing structure 21 in contact with the outer cylinder 1 is provided on the outer wall of the lower sleeve assembly 6. A plurality of third static sealing structures 21 are arranged in the axial direction of the lower sleeve assembly 6.

[0028] The static seals are O-rings, and the dynamic seals are VL combination seals. The lower seal 26 uses a combination of static and dynamic seals to seal the buffer chamber 101 (oil-air mixing chamber) from the outside atmosphere during takeoff and landing.

[0029] like Figure 2 As shown, the piston rod 9 is provided with a retaining ring 8, and the end of the lower sleeve assembly 6 is provided with a limiting ring 7 that abuts against the retaining ring 8. The retaining ring 8 is connected to the lower sleeve assembly 6 by a screw 11 (as shown in FIG. Figure 5 As shown in the figure). Figure 8As shown, the retaining ring 7 is a three-section annular structure. The lower sleeve assembly 6 has a mounting opening at its end near the retaining ring 8. An annular groove is provided on the inner wall of the outer tube 1, aligned with the mounting opening for mounting the retaining ring 7. The retaining ring 7 prevents the lower sleeve assembly 6 from falling out of the landing gear. A dust ring 10 is located inside the retaining ring 8 to remove foreign matter and prevent it from entering and damaging the sealing ring.

[0030] like Figure 1 As shown, an oil needle 16 is disposed within the inner cavity of the piston rod 9. An O-ring 3 is mounted on one end of the oil needle 16, contacting the inner wall of the piston rod 9. A damping ring 13 is mounted on the other end of the oil needle 16. The damping ring 13 is positioned adjacent to the plunger 14. An upper support sleeve 12 is mounted externally on the end of the piston rod 9 where the damping ring 13 is located. The upper support sleeve 12 is in sliding contact with the outer cylinder 1.

[0031] The present invention aims to solve the problem of designing the external sealing structure of the landing gear buffer. The buffer in the present invention is divided into a non-functional cavity and a functional cavity. The non-functional cavity is a lightening cavity, and the middle cavity is a conventional oil and gas buffer cavity, and the external sealing is achieved through both ends. In the complex working conditions of landing gear installation and use, there is often a tendency of relative rotation between the parts where the sealing joint surface is located and the outer cylinder, which should take into account the influence of external ground loads and the pressure in the buffer cavity. The intermediate sealing structure changes the connection form. The installed oil nozzle mounting seat and its nested oil limiting tube can not only provide oil to the buffer but also stop the rotation of the plunger. In addition, the oil limiting tube passes through the plunger and the oil nozzle mounting seat at the same time, which also stops the rotation of the oil nozzle mounting seat. The two ingenious anti-rotation structures avoid the rotation trend causing the sealing ring to twist, improve the structural stability of the sealing surface, and thus enhance the sealing reliability; the upper and lower sealing structures improve the manufacturability of high-precision machining of the outer cylinder sealing surface by eliminating the threaded structure at the outer cylinder seal, thereby reducing the sealing failure caused by the roughness of the sealing surface and the difficulty in ensuring the form and position tolerances, thereby reducing the cost of the product and improving the economy and reliability of the product. In addition, the oil-fixing structure set in the buffer is convenient for field use and maintenance, and accurate oil fixing can be completed without returning to the factory, which greatly reduces the use and maintenance cost of the product.

[0032] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A landing gear buffer, comprising an outer tube (1) and a piston rod (9) telescopically arranged in the outer tube (1), wherein the piston rod (9) has an inner cavity, a plunger (14) is arranged in the outer tube (1), and one end of the plunger (14) extends into the inner cavity of the piston rod (9), characterized in that: The plunger (14) divides the outer cylinder (1) into a buffer chamber (101) and a non-functional chamber (102), and one end of the piston rod (9) is located in the buffer chamber (101); an upper end seal (24) for isolating the non-functional chamber (102) from the atmosphere is provided in the outer cylinder (1); an oil limiting pipe seal (25) for injecting oil into the buffer chamber (101) and for stopping the plunger (14) from rotating is provided between the plunger (14) and the outer cylinder (1); a first static sealing structure (15) for isolating the buffer chamber (101) from the non-functional chamber (102) is provided on the plunger (14); and a lower end seal (26) for isolating the buffer chamber (101) from the atmosphere is provided between the piston rod (9) and the outer cylinder (1).

2. The landing gear buffer according to claim 1, characterized in that: The upper end seal (24) comprises a stop bolt (2) provided on the side of the outer cylinder (1) close to the non-functional cavity (102), and an end cover (5) provided on the side of the outer cylinder (1) away from the non-functional cavity (102). The end cover (5) is connected to the stop bolt (2) and fixed by a nut (4). An O-ring (3) is provided between the end cover (5) and the outer cylinder (1) and between the end cover (5) and the stop bolt (2).

3. The landing gear buffer according to claim 2, characterized in that: The stop bolt (2) includes a connecting plate (201) and a connecting shaft (202) connected to the middle of one side of the connecting plate (201). The end of the connecting plate (201) is provided with a step (203) for clamping the outer cylinder (1). The end cover (5) and the O-ring (3) are both mounted on the connecting shaft (202), and the nut (4) is connected to the connecting shaft (202).

4. The landing gear buffer according to claim 1, characterized in that: The oil limiting pipe seal (25) includes an oiling nozzle mounting seat (18) inserted into the outer cylinder (1) and the plunger (14) at the same time on an axis perpendicular to the piston rod (9), an oil limiting pipe (20) is provided in the plunger (14), a first oil circuit (181) is provided in the oiling nozzle mounting seat (18), a second oil circuit (2004) is provided in the oil limiting pipe (20), and the second oil circuit (2004) connects the first oil circuit (181) and the buffer chamber (101); a second static sealing structure (19) is provided between the oiling nozzle mounting seat (18) and the outer cylinder (1) and between the oil limiting pipe (20) and the plunger (14).

5. The landing gear buffer according to claim 4, characterized in that: The oil limiting pipe (20) comprises a first shaft portion (2005) and a second shaft portion (2006) vertically connected to one end of the first shaft portion (2005); the second oil circuit (2004) is provided in the first shaft portion (2005) and the second shaft portion (2006); the first shaft portion (2005) is provided with an interface (2001) that passes through the side wall of the first shaft portion (2005) and communicates with the second oil circuit (2004); the second oil circuit (2004) passes through the side wall of the first shaft portion (2005); A hole plane (2003) is formed on one side of the second shaft portion (2006); the second static sealing structure (19) is provided on the first shaft portion (2005); the first shaft portion (2005) is inserted into the plunger (14), the end of the oiling nozzle mounting seat (18) extends into the interface (2001), the second shaft portion (2006) is located outside the plunger (14), and the hole plane (2003) is provided toward the upper end seal (24).

6. The landing gear buffer according to claim 1, characterized in that: The lower end seal (26) includes a lower sleeve assembly (6) sleeved between the outer cylinder (1) and the piston rod (9), a dynamic sealing structure (22) and a support ring (23) in contact with the piston rod (9) are provided on the inner wall of the lower sleeve assembly (6), and a third static sealing structure (21) in contact with the outer cylinder (1) is provided on the outer wall of the lower sleeve assembly (6).

7. The landing gear buffer according to claim 6, characterized in that: The dynamic sealing structure (22), the support ring (23) and the third static sealing structure (21) are all arranged in a plurality in the axial direction of the lower shaft sleeve assembly (6), and one dynamic sealing structure (22) is provided between two adjacent support rings (23).

8. The landing gear buffer according to claim 6, characterized in that: A retaining ring (8) is mounted on the piston rod (9), a limiting ring (7) abutting against the retaining ring (8) is mounted on the end of the lower shaft sleeve assembly (6), and the retaining ring (8) is connected to the lower shaft sleeve assembly (6) via a screw (11).

9. The landing gear buffer according to claim 8, characterized in that: The limiting ring (7) is a three-section ring structure.

10. The landing gear buffer according to claim 1, characterized in that An oil needle (16) is provided in the inner cavity of the piston rod (9), one end of the oil needle (16) is provided with an O-ring (3) in contact with the inner wall of the piston rod (9), and the other end of the oil needle (16) is sleeved with a damping ring (13), and the damping ring (13) is arranged close to the plunger (14); an upper support sleeve (12) is provided on the outside of the end of the piston rod (9) provided with the damping ring (13), and the upper support sleeve (12) is in sliding contact with the outer cylinder (1).

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