A magnetorheological fluid aircraft landing gear buffer strut

Abstract

The invention discloses a magnetorheological fluid aircraft landing gear buffer strut, comprising an outer cylinder, an inner cylinder, a floating piston, a piston rod, an electromagnetic control assembly, a liner and an oil needle; the inner cylinder is located inside the outer cylinder; the floating piston is installed between the inner cylinder and the outer cylinder; the lower end of the inner cylinder extends into the piston rod; the piston rod extends from the outer cylinder; the electromagnetic control assembly is installed on the closed end of the piston rod; the electromagnetic control assembly generates a magnetic field after being energized; the upper end of the liner is sleeved on the inner cylinder, and the lower end is installed on the electromagnetic control assembly; the oil needle comprises an upper cut-off section and a lower cut-off section connected at both ends of the middle section; the invention can meet various complex working conditions faced by aircraft landing, that is, it can meet the aircraft landing shock requirements, and can also effectively reduce the overall natural frequency, and better isolate the vibration from the ground during the taxiing process.

Description

Technical Field

[0001] The invention relates to the field of buffer technology, in particular to a magnetorheological fluid aircraft landing gear buffer strut. Background Art

[0002] Buffers are essential universal components for modern aircraft landing gears. The main function of the buffer is to absorb the vertical kinetic energy during the landing and taxiing of the aircraft. Landing gear with good buffering performance can make the aircraft and landing gear have lower aircraft overload, better stability, comfort and higher reliability during landing, taxiing and ground operation. Since oil-gas buffers have the highest efficiency and the best power absorption capacity, at present, most landing gears at home and abroad use oil-gas buffer landing gears. Oil-gas buffers generally have single-chamber and double-chamber types. In order to better coordinate the drop shock dynamics of the aircraft landing process and the taxiing dynamics of the aircraft when taxiing on the runway, and better adapt to the impact of landing loads, double-chamber oil-gas buffers have advantages and are more widely used.

[0003] By the attached Figure 3 As shown, the double-chamber oil-gas buffer is designed with a low-pressure air chamber Q1 and a high-pressure air chamber Q2. When the buffer strut is compressed, the variable-section oil needle can change the flow area of ​​the main oil hole, and the hydraulic oil generates the buffer damping force required by the stroke change through the main oil hole; the piston rod first compresses the gas in the low-pressure air chamber Q1, and when the piston rod contacts the floating piston, it continues to compress the gas in the high-pressure air chamber Q2.

[0004] When the aircraft lands and touches the ground (ship), the aircraft sinks at a speed of about 3m / s (land-based aircraft) and up to 7m / s (carrier-based aircraft). The buffer needs to have both a large deformation capacity and the ability to withstand a larger impact load. In addition to the support capacity obtained by the compressed air spring, the traditional double-chamber oil-gas buffer forces the working medium (oil) to pass through the main oil hole during compression. The main oil hole and the variable-section oil needle cooperate with each other to change the flow area of ​​the main oil hole according to the stroke, thereby achieving the purpose of adjusting the damping force of the buffer.

[0005] However, the throttling capacity with a certain regulating effect formed only by the main oil hole and the oil needle has limited buffering and vibration reduction effects when dealing with various complex working conditions faced by aircraft landing, and once the oil needle is designed and installed in place, this throttling capacity cannot be changed according to the complex working conditions faced by the aircraft. Accordingly, when the magnetorheological buffer is intelligently transformed, the working medium is replaced with magnetorheological fluid, and the electromagnetic control of the flow channel is integrated in the structural design to achieve controllable damping force, if the structural design scheme is not fundamentally innovated, it is difficult to ensure its effective control and normal operation due to the sedimentation problem of soft magnetic particles in the magnetorheological fluid.

[0006] Therefore, in order to carry out the magnetorheological controllable damping innovation of the existing buffer pillar, a buffer pillar that can solve the above problems at the same time is needed. Summary of the invention

[0007] The technical solution adopted to achieve the purpose of the present invention is as follows: a magnetorheological fluid aircraft landing gear buffer strut includes an outer tube, an inner tube, a floating piston, a piston rod, an electromagnetic control component, a liner and an oil needle.

[0008] The upper end of the outer cylinder is closed, and a through hole I is provided on the lower end surface.

[0009] The inner cylinder is located inside the outer cylinder, with its upper end connected to the closed portion of the upper end of the outer cylinder, and its lower end extending from the through hole I of the outer cylinder.

[0010] The lower end surface of the inner cylinder is provided with a through hole II. The inner wall of the inner cylinder is provided with a plurality of layers of through holes III.

[0011] The outer wall of the inner cylinder and the inner wall of the outer cylinder form a cavity S. The interior of the inner cylinder is an inner cavity.

[0012] The floating piston is installed between the inner cylinder and the outer cylinder. The floating piston separates the cavity S, and an air cavity is formed above the floating piston.

[0013] The upper end of the piston rod is open, and the lower end is a closed end. The upper end of the piston rod has an inner curling edge extending inwardly and an outer curling edge extending outwardly.

[0014] The lower end of the inner cylinder extends into the piston rod. The piston rod extends from the through hole I of the outer cylinder.

[0015] The inner and outer curls of the piston rod separate the cavity S, forming an annular cavity I between the upper part of the inner and outer curls and the floating piston, and a side oil cavity between the lower part of the outer curl and the lower end of the outer cylinder. The outer curl is provided with a plurality of through holes IV. The side oil cavity is connected to the annular cavity I through the through hole IV. The annular cavity I is connected to the inner cavity through the through hole III.

[0016] The electromagnetic control component is mounted on the closed end of the piston rod and generates a magnetic field when energized.

[0017] The liner is located in the piston rod, the upper end of which is sleeved on the inner cylinder and contacts the inner curling edge of the piston rod, and the lower end of which is installed on the electromagnetic control component.

[0018] A flow chamber is formed between the outer wall of the liner and the inner wall of the piston rod. The flow chamber is connected to the side oil chamber by opening a through hole V on the inner wall of the piston rod. A lower oil chamber is formed in the liner. There is a space in the electromagnetic control component that connects the lower oil chamber and the flow chamber.

[0019] The lower oil cavity and the inner cavity are filled with magnetorheological fluid.

[0020] The oil needle includes an upper cut-off section and a lower cut-off section connected to both ends of the middle section. The cross-sections of the upper cut-off section and the lower cut-off section are adapted to the through hole II. The cross-sectional area of ​​the upper cut-off section is larger than the cross-sectional area of ​​the middle section. The oil needle is located in the piston rod, the lower cut-off section is mounted on the electromagnetic control assembly, and the upper cut-off section penetrates into the through hole II of the inner cylinder.

[0021] When the piston rod extends upward, the upper cut-off section gradually extends into the inner cylinder and blocks the through hole II. The magnetorheological fluid in the lower oil chamber enters the flow chamber through the electromagnetic control assembly, and flows into the side oil chamber, annular chamber I, and inner chamber in sequence. The gas in the inner chamber and annular chamber I is compressed. When the piston rod contacts the floating piston, it pushes the floating piston to compress the air chamber, and at the same time, the middle section of the oil needle penetrates into the through hole II of the inner cylinder, and the magnetorheological fluid flows from the lower oil chamber through the through hole II into the inner chamber. The gas in the inner chamber and annular chamber I continues to be compressed. When the lower cut-off section of the oil needle penetrates into the through hole II, the through hole II is blocked. The magnetorheological fluid enters the flow chamber from the lower oil chamber through the electromagnetic control assembly, and flows into the side oil chamber, annular chamber I, and inner chamber in sequence. The gas in the inner chamber, air chamber, and annular chamber I is further compressed.

[0022] When the aircraft is stored in the warehouse, the buffer strut supports the aircraft and remains stationary for a long time. The aircraft's own weight compresses the buffer strut, and the middle section of the oil needle penetrates into the through hole II of the inner tube.

[0023] Furthermore, the electromagnetic control assembly includes a positioning column, a top cover, an electromagnetic element, a power device and a rotor.

[0024] The center of the upper end surface of the closed end of the piston rod is provided with a through hole VII. The upper end surface of the closed end is provided with a plurality of blind holes on the same circumference.

[0025] There are a plurality of positioning posts, and each positioning post is correspondingly installed in a blind hole at the closed end.

[0026] The electromagnetic element is located in the piston rod, and its lower end is fixed on the positioning column. An outer coil is wound around the electromagnetic element.

[0027] The center of the end face of the top cover has a circular hole II. The end face of the top cover is provided with a plurality of through holes VI on the same circumference. The top cover is fixed on the upper end face of the stator. The end face of the upper end of the top cover has a circular annular boss. The lower end of the liner is sleeved on the circular annular boss.

[0028] The rotor has a protruding shaft at the center of the end surface at both ends. The rotor is located inside the electromagnetic element, and the protruding shaft at the lower end is inserted into the through hole VII at the closed end, and the protruding shaft at the upper end is inserted into the circular hole II of the top cover.

[0029] An inner channel is formed between the rotor and the electromagnetic element. The inner channel is connected to the through hole VI of the top cover. An outer channel is formed between the electromagnetic element and the piston rod. The lower end of the electromagnetic element is supported by a positioning column, and a space connecting the inner channel and the outer channel is formed below the electromagnetic element.

[0030] The power device is located outside the piston rod. The power device is connected to the closed end of the piston rod, and the output end of the power device penetrates the through hole VII of the closed end and is fixedly connected to the extended shaft at the lower end of the rotor. The power device is connected to an external power source.

[0031] When direct current is applied to the outer coil of the electromagnetic element, the outer coil generates a uniformly distributed magnetic field in the outer channel. When the external power source drives the power device, the output end of the power device drives the rotor to rotate, and the rotor drives the magnetorheological fluid to generate a rotating flow.

[0032] Furthermore, the power device is a motor or a rotating handle.

[0033] Furthermore, the electromagnetic element is a yoke.

[0034] Furthermore, the positioning column has a through hole VIII inside, the through hole VIII is connected to the blind hole at the closed end, and a lead hole is provided at the bottom of the blind hole.

[0035] Furthermore, the floating piston includes an upper ring, a connecting portion and a lower ring.

[0036] The connecting portion is connected between the upper circular ring and the lower circular ring.

[0037] An annular stopper protrudes from the outer wall of the inner cylinder. Several layers of through holes III are located below the annular stopper. A sealing ring is installed on the outer wall of the upper circular ring. The upper circular ring is clamped on the upper end of the annular stopper of the inner cylinder.

[0038] The space between the upper ring and the lower ring is separated by the connecting part, one side is the outer wall of the inner cylinder, and the other side is the inner wall of the outer cylinder, and the space between the connecting part and the inner cylinder is recorded as an annular cavity II. The annular cavity II is connected to the inner cavity through the through hole III.

[0039] Furthermore, the connecting portion is cylindrical, and its outer wall is wrapped with anti-friction material.

[0040] Furthermore, the annular limiting platform is a circular annular flange.

[0041] There is a gap between the lower circular ring and the inner wall of the inner cylinder, and the gap is larger than the width of the annular limiting platform.

[0042] Furthermore, the upper cut-off section and the through hole II are clearance-matched, and the clearance between the upper cut-off section and the through hole II is recorded as L, wherein 0<L≤0.1mm.

[0043] The technical effect of the present invention is undoubted, and it has the following advantages:

[0044] 1) When the piston rod extends upward, the upper cut-off section gradually extends into the inner cylinder, corresponding to the buffer strut working in the drop shock zone when the aircraft lands; the gas in the inner cavity and the annular cavity I is compressed to generate an elastic force to support the weight of the aircraft; the magnetorheological fluid generates a large controllable damping force under the controllable magnetic field generated by the electromagnetic control component to alleviate the drop shock impact.

[0045] 2) When the middle section of the oil needle penetrates through hole II, it corresponds to the taxiing area after the aircraft takes off or lands, forming a smaller damping force working state determined by the variable cross-section design of the oil needle, effectively isolating the vibration transmitted from the runway to the aircraft body through the buffer strut.

[0046] 3) When the lower cut-off section of the oil needle penetrates into the through hole II, the compression of the buffer pillar will exceed the sliding area and enter the limit area. At this time, the air cavity produces a greater elastic force due to the large compression amount to prevent the buffer pillar from being overly compressed; the magnetorheological fluid generates a large controllable damping force to relieve vibration under the controllable magnetic field generated by the electromagnetic control component.

[0047] 4) The rotation of the rotor causes the magnetorheological fluid to rotate and flow, thus solving the sedimentation problem of the magnetorheological fluid.

[0048] In summary, the present invention can meet various complex working conditions faced by aircraft landing, not only meet the aircraft landing shock requirements, but also effectively reduce the overall natural frequency, better isolate the vibration from the ground during the taxiing process, and solve the sedimentation problem of magnetorheological fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of the present invention;

[0050] Figure 2 for Figure 1 Schematic diagram of the structure of the middle rotor;

[0051] Figure 3 It is a schematic diagram of the structure of a double-cavity oil-gas buffer in the prior art.

[0052] In the figure: outer cylinder 1, through hole I101, inner cylinder 2, through hole II201, annular limit platform 202, through hole III203, floating piston 3, upper ring 301, connecting part 302, lower ring 303, piston rod 4, closed end 41, round hole I411, blind hole 412, through hole VII413, inner curling edge 42, outer curling edge 43, through hole IV431, through hole V44, electromagnetic control component 5, positioning column 52, top cover 5 4. circular hole II541, through hole VI542, annular boss 543, electromagnetic element 55, outer coil 551, power device 56, rotor 57, extending shaft 571, bushing 6, oil needle 7, upper cut-off section 701, middle section 702, lower cut-off section 703, inner cavity S1, air cavity S2, annular cavity IS3, side oil cavity S4, flow cavity S5, lower oil cavity S6, annular cavity IIS7, low-pressure air chamber Q1 and high-pressure air chamber Q2. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0054] Embodiment 1:

[0055] See also Figure 1 The present embodiment discloses a magnetorheological fluid aircraft landing gear buffer strut including an outer tube 1, an inner tube 2, a floating piston 3, a piston rod 4, an electromagnetic control component 5, a liner 6 and an oil needle 7.

[0056] The outer tube 1 is a hollow cylinder with a closed upper end and a through hole I101 on the lower end surface.

[0057] The inner cylinder 2 is a hollow cylinder and is located inside the outer cylinder 1. The upper end of the inner cylinder 2 is connected to the closed part of the upper end of the outer cylinder 1, and the two form a whole. The lower end of the inner cylinder 2 extends out from the through hole 1101 of the outer cylinder 1.

[0058] A through hole II201 is provided on the lower end surface of the inner cylinder 2. An annular stopper 202 is protruded on the outer wall of the inner cylinder 2. The annular stopper 202 is a circular annular flange. Four layers of through holes III203 are opened on the inner wall of the inner cylinder 2. The four layers of through holes III203 are all located below the annular stopper 202.

[0059] The outer wall of the inner tube 2 and the inner wall of the outer tube 1 form a cavity S. The interior of the inner tube 2 is an inner cavity S1.

[0060] The floating piston 3 includes an upper ring 301 , a connecting portion 302 and a lower ring 303 .

[0061] The connecting portion 302 is connected between the upper ring 301 and the lower ring 303 .

[0062] The floating piston 3 is installed between the inner cylinder 2 and the outer cylinder 1. The upper ring 301 of the floating piston 3 is clamped on the upper end of the annular stopper 202 of the inner cylinder 2. The upper ring 301 of the floating piston 3 divides the cavity S, and an air cavity S2 is formed above the floating piston 3. A sealing ring is installed on the outer wall of the upper ring 301. The air cavity S2 is completely closed by the sealing ring.

[0063] The connecting part 302 is cylindrical, and its outer wall is wrapped with friction-reducing material. The space between the upper ring 301 and the lower ring 303 is divided by the connecting part 302, one side is the outer wall of the inner cylinder 2, and the other side is the inner wall of the outer cylinder 1. The space between the connecting part 302 and the inner cylinder 2 is recorded as the annular cavity IIS8. The annular cavity IIS8 is connected to the inner cavity S1 through the through hole III203.

[0064] The piston rod 4 is a hollow cylinder, with an open upper end and a closed lower end 41. An inner curling edge 42 extends inwardly from the open upper end of the piston rod 4, and an outer curling edge 43 extends outwardly.

[0065] The lower end of the inner cylinder 2 extends into the piston rod 4. The piston rod 4 extends from the through hole I101 of the outer cylinder 1.

[0066] The inner curl 42 and the outer curl 43 of the piston rod 4 separate the cavity S, and an annular cavity IS3 is formed between the upper part of the inner curl 42 and the outer curl 43 and the floating piston 3, and a side oil cavity S4 is formed between the lower part of the outer curl 43 and the lower end of the outer cylinder 1. The outer curl 43 is provided with a plurality of through holes IV431. The side oil cavity S4 is connected to the annular cavity IS3 through the through hole IV431. The annular cavity IS3 is connected to the inner cavity S1 through the through hole III203.

[0067] The electromagnetic control assembly 5 includes a positioning column 52 , a top cover 54 , an electromagnetic element 55 , a power device 56 and a rotor 57 .

[0068] The center of the upper end surface of the closed end 41 of the piston rod 4 is provided with a through hole VII413. The upper end surface of the closed end 41 is provided with a plurality of blind holes 412 on the same circumference. The closed end 41 is connected to the lower end of the piston rod 4 by threads.

[0069] There are multiple positioning posts 52, and each positioning post 52 is installed in a corresponding blind hole 412 of the closed end 41. The positioning post 52 has a through hole VIII inside. The through hole VIII is connected to the blind hole 412 of the closed end 41. The bottom of the blind hole 412 is provided with a lead hole.

[0070] The electromagnetic element 55 is a magnetic yoke, which is located in the piston rod 4, and a positioning hole is set at the lower end of the magnetic yoke to be fixed on the positioning column 52. An external coil 551 is wound on the electromagnetic element 55. The lead wire 5511 of the external coil 551 is led out through the through hole VIII on the positioning column 52, and passes through the lead wire hole at the bottom of the blind hole 412 to pass through the closed end 41 and connect to an external power supply.

[0071] The center of the end face of the top cover 54 has a circular hole II541. The end face of the top cover 54 is provided with a plurality of through holes VI542 on the same circumference. The top cover 54 is fixed to the upper end face of the electromagnetic element 55. The upper end face of the top cover 54 has a circular annular boss 543. The lower end of the bushing 6 is sleeved on the circular annular boss 543.

[0072] The rotor 57 is a cylinder, and the center of the end faces of both ends of the rotor 57 has a protruding shaft 571. The rotor 57 is located inside the electromagnetic element 55, and the protruding shaft 571 at the lower end is inserted into the through hole VII413 of the closed end 41, and the protruding shaft 571 at the upper end is inserted into the circular hole II541 of the top cover 54. The outer wall of the rotor 57 is processed with spiral ribs.

[0073] An inner channel is formed between the rotor 57 and the electromagnetic element 55. The inner channel is connected to the through hole VI542 of the top cover 54. An outer channel is formed between the electromagnetic element 55 and the piston rod 4. The lower end of the electromagnetic element 55 is supported by the positioning column 52, and a space connecting the inner channel and the outer channel is formed below the electromagnetic element 55.

[0074] The power device 56 is a motor, which is located outside the piston rod 4. The output shaft of the motor passes through the through hole VII413 of the closed end 41, and is fixedly connected to the extended shaft 571 at the lower end of the rotor 57 through a coupling, and a sealing ring is put on to ensure sealing. The motor is connected to an external power supply.

[0075] When direct current is applied to the outer coil 551 of the magnetic yoke, the outer coil 551 generates a uniformly distributed magnetic field in the outer channel. When the external power source drives the motor, the output shaft of the motor drives the rotor 57 to rotate, and the rotor 57 drives the magnetorheological fluid to generate a rotating flow.

[0076] The liner 6 is located in the piston rod 4 , with its upper end sleeved on the inner cylinder 2 and in contact with the inner curling edge 42 of the piston rod 4 , and its lower end sleeved on the annular boss 543 .

[0077] A flow chamber S5 is formed between the outer wall of the liner 6 and the inner wall of the piston rod 4. The flow chamber S5 is connected to the side oil chamber S4 by opening a through hole V44 on the inner wall of the piston rod 4. A lower oil chamber S6 is formed in the liner 6. The lower oil chamber S6 is connected to the flow chamber S5 through an inner channel and an outer channel.

[0078] The lower oil chamber S6 and the inner chamber S1 are filled with magnetorheological fluid. When the piston rod 4 is stretched to the maximum, the liquid level of the magnetorheological fluid should preferably cover the top of the piston rod 4. The specific liquid level is determined by the initial gas filling volume required by the buffer support.

[0079] The oil needle 7 includes an upper cut-off section 701 and a lower cut-off section 703 connected at both ends of the middle section 702. The cross-sections of the upper cut-off section 701 and the lower cut-off section 703 are adapted to the through hole II201. The cross-sectional area of ​​the upper cut-off section 701 is greater than the cross-sectional area of ​​the middle section 702. The middle section 702 is a variable cross-sectional cylinder, and its maximum cross-sectional area is smaller than the cross-sectional area of ​​the upper cut-off section 701. The oil needle 7 is located in the piston rod 4, and its lower cut-off section 703 is fixed on the top cover 54 of the electromagnetic control component 5. The upper cut-off section 701 penetrates into the through hole II201 of the inner cylinder 2 and is in clearance fit with the through hole II201. The clearance between the upper cut-off section 701 and the circular through hole II2011 is L. In the embodiment, L is 0.1 mm.

[0080] When the buffer strut works to suppress the drop shock and taxiing vibration of the aircraft, direct current is passed through the external coil 551, and the electromagnetic element 55 acts as a magnetic conductor to form a uniformly distributed magnetic field in the external channel to achieve the damping control function.

[0081] When the piston rod 4 extends upward, the buffer support works in the drop shock zone when the aircraft lands, and the upper cut-off section 701 gradually extends into the inner tube 2 and blocks the through hole II201. Since the gap between the upper cut-off section 701 and the through hole II201 of the inner tube 2 is very small, it is difficult for the magnetorheological fluid to pass through the through hole II201 at this time. The magnetorheological fluid in the lower oil chamber S6 enters the flow chamber S5 through the inner channel and the outer channel of the electromagnetic control component 5, flows into the side oil chamber S4 through the through hole V44 on the piston rod 4, and then flows into the annular chamber IS3 through the through hole IV431 on the outer curling edge 43, and finally flows into the inner chamber S1 through the through hole III203 on the inner tube 2. The gas in the inner chamber S1, the annular chamber IIS7 and the annular chamber IS3 is compressed to generate an elastic force that supports the weight of the aircraft. In the inner channel, the damping force generated by the flow is changed due to the magnetorheological effect, thereby realizing a buffer pillar with controllable damping. The current size is closed-loop controlled according to the motion state of the buffer pillar. Under the action of the controllable magnetic field generated by the outer coil 551, the magnetorheological fluid generates a large controllable damping force to alleviate the impact of falling shock.

[0082] When the piston rod 4 contacts the floating piston 3, it pushes the floating piston 3 to compress the air chamber S2, and at the same time, the middle section 702 of the oil needle 7 penetrates into the through hole II201 of the inner tube 2, corresponding to the taxiing area after the aircraft takes off or the impact of landing, the magnetorheological fluid flows from the lower oil chamber S7 through the through hole II201 into the inner chamber S1, forming a smaller damping force working state determined by the variable cross-section design of the middle section 702, effectively isolating the vibration transmitted from the runway to the aircraft body through the buffer pillar, which will greatly reduce the natural frequency of the whole system. The gas in the inner chamber S1, the annular chamber IIS7 and the annular chamber IS3 continues to be compressed.

[0083] When the lower cut-off section 703 of the oil needle 7 penetrates the through hole II201, the through hole II201 is blocked. Since the gap between the lower cut-off section 703 and the through hole II201 of the inner cylinder 2 is very small, it is difficult for the magnetorheological fluid to pass through the through hole II201 at this time, and the compression amount of the buffer pillar will exceed the sliding area and enter the limit area. At this time, the air cavity S2 generates a greater elastic force due to the large compression amount to prevent the buffer pillar from generating excessive compression. The magnetorheological fluid enters the flow cavity S5 from the lower oil cavity S7 through the electromagnetic control component 5, flows into the side oil cavity S4 through the through hole V44 on the piston rod 4, and then flows into the annular cavity IS3 through the through hole IV431 on the outer curling edge 43, and finally flows into the inner cavity S1 through the through hole III203 on the inner cylinder 2. The gas in the inner cavity S1, the air cavity S2, the annular cavity IIS7 and the annular cavity IS3 is further compressed. In the inner channel, the magnetorheological fluid generates a large controllable damping force to relieve vibration under the controllable magnetic field generated by the outer coil 551.

[0084] When the piston rod 4 is restored, the compressed air chamber S2 pushes the floating piston 3 to move downward until the floating piston 3 is limited by the annular stopper 202. The floating piston 3 pushes the piston rod 4 to move downward, and the magnetorheological fluid flows from the inner chamber S1 through the through hole III203 into the annular chamber IS3, flows through the side oil chamber S4 and the flow chamber S5 in turn, and flows into the lower oil chamber S6 through the outer channel and the inner channel. When the middle section 702 of the oil needle 7 retreats to the through hole II201, the magnetorheological fluid flows from the inner chamber S1 through the through hole II201 into the lower oil chamber S6. When the upper stop section 701 of the oil needle 7 retreats to the circular through hole II201, the magnetorheological fluid flows from the inner chamber S1 through the through hole III203 into the annular chamber IS3, flows through the side oil chamber S4 and the flow chamber S5 in turn, and flows into the lower oil chamber S6 through the outer channel and the inner channel. When the upper cut-off section 701 of the oil needle 7 retracts to the initial state, the air pressures of the inner cavity S1, the air cavity S2, the annular cavity IS3 and the annular cavity IIS7 return to the initial state.

[0085] When the aircraft is stored in the warehouse, the buffer strut supports the aircraft and is in a static state for a long time. The weight of the aircraft compresses the buffer strut, and the middle section 702 of the oil needle 7 penetrates into the through hole II201 of the inner cylinder 2. The motor is energized in time based on the sedimentation state of the magnetorheological fluid, and the output shaft of the motor drives the rotor 57 to rotate, so that the settled magnetorheological fluid can be redispersed.

[0086] Furthermore, there is a gap between the lower ring 303 and the inner wall of the inner tube 2 , and the gap is larger than the width of the annular stopper 202 , so that the lower ring 303 can pass through the annular stopper 202 when the floating piston 3 slides upward.

[0087] The magnetorheological fluid aircraft landing gear buffer strut disclosed in this embodiment can meet the various complex working conditions faced by aircraft landing. It can not only meet the aircraft landing shock requirements, but also effectively reduce the overall natural frequency, better isolate the vibration from the ground during taxiing, and solve the sedimentation problem of magnetorheological fluid.

[0088] Embodiment 2:

[0089] This embodiment discloses a relatively basic implementation method, see Figure 1 A magnetorheological fluid aircraft landing gear buffer strut includes an outer tube 1, an inner tube 2, a floating piston 3, a piston rod 4, an electromagnetic control component 5, a liner 6 and an oil needle 7.

[0090] The outer tube 1 is a hollow cylinder with a closed upper end and a through hole I101 on the lower end surface.

[0091] The inner cylinder 2 is a hollow cylinder and is located inside the outer cylinder 1. The upper end of the inner cylinder 2 is connected to the closed part of the upper end of the outer cylinder 1, and the two form a whole. The lower end of the inner cylinder 2 extends out from the through hole 1101 of the outer cylinder 1.

[0092] A through hole II201 is provided on the lower end surface of the inner cylinder 2. Four layers of through holes III203 are opened on the inner wall of the inner cylinder 2.

[0093] The outer wall of the inner tube 2 and the inner wall of the outer tube 1 form a cavity S. The interior of the inner tube 2 is an inner cavity S1.

[0094] The floating piston 3 is installed between the inner tube 2 and the outer tube 1. The floating piston 3 divides the cavity S, and an air cavity S2 is formed above the floating piston 3.

[0095] The piston rod 4 is a hollow cylinder, with an open upper end and a closed lower end 41. An inner curling edge 42 extends inwardly from the open upper end of the piston rod 4, and an outer curling edge 43 extends outwardly.

[0096] The lower end of the inner cylinder 2 extends into the piston rod 4. The piston rod 4 extends from the through hole I101 of the outer cylinder 1.

[0097] The inner curl 42 and the outer curl 43 of the piston rod 4 separate the cavity S, and an annular cavity IS3 is formed between the upper part of the inner curl 42 and the outer curl 43 and the floating piston 3, and a side oil cavity S4 is formed between the lower part of the outer curl 43 and the lower end of the outer cylinder 1. The outer curl 43 is provided with a plurality of through holes IV431. The side oil cavity S4 is connected to the annular cavity IS3 through the through hole IV431. The annular cavity IS3 is connected to the inner cavity S1 through the through hole III203.

[0098] The electromagnetic control component 5 is mounted on the closed end 41 of the piston rod 4. The electromagnetic control component 5 generates a magnetic field when powered on.

[0099] The liner 6 is located inside the piston rod 4 , with its upper end sleeved on the inner tube 2 and in contact with the inner curling edge 42 of the piston rod 4 , and its lower end mounted on the electromagnetic control assembly 5 .

[0100] A flow chamber S5 is formed between the outer wall of the liner 6 and the inner wall of the piston rod 4. The flow chamber S5 is connected to the side oil chamber S4 by opening a through hole V44 on the inner wall of the piston rod 4. A lower oil chamber S6 is formed in the liner 6. The lower oil chamber S6 is connected to the flow chamber S5 through an inner channel and an outer channel.

[0101] The lower oil chamber S6 and the inner chamber S1 are filled with magnetorheological fluid. When the piston rod 4 is stretched to the maximum, the liquid level of the magnetorheological fluid should preferably cover the top of the piston rod 4. The specific liquid level is determined by the initial gas filling volume required by the buffer support.

[0102] The oil needle 7 includes an upper cut-off section 701 and a lower cut-off section 703 connected at both ends of the middle section 702. The cross-sections of the upper cut-off section 701 and the lower cut-off section 703 are adapted to the through hole II201. The cross-sectional area of ​​the upper cut-off section 701 is larger than the cross-sectional area of ​​the middle section 702. The middle section 702 is a variable cross-sectional cylinder, and its maximum cross-sectional area is smaller than the cross-sectional area of ​​the upper cut-off section 701. The oil needle 7 is located in the piston rod 4, and its lower cut-off section 703 is installed on the electromagnetic control assembly 5, and the upper cut-off section 701 penetrates into the through hole II201 of the inner cylinder 2.

[0103] When the buffer strut works to suppress the drop shock and taxiing vibration of the aircraft, the electromagnetic control component 5 is energized to generate a magnetic field to achieve the damping control function.

[0104] When the piston rod 4 extends upward, the buffer strut works in the drop shock zone when the aircraft lands, and the upper cut-off section 701 gradually extends into the inner tube 2 and blocks the through hole II201. Since the gap between the upper cut-off section 701 and the through hole II201 of the inner tube 2 is very small, it is difficult for the magnetorheological fluid to pass through the through hole II201 at this time. The magnetorheological fluid in the lower oil chamber S6 enters the flow chamber S5 through the electromagnetic control component 5, flows into the side oil chamber S4 through the through hole V44 on the piston rod 4, and then flows into the annular chamber IS3 through the through hole IV431 on the outer curling edge 43, and finally flows into the inner chamber S1 through the through hole III203 on the inner tube 2. The gas in the inner chamber S1 and the annular chamber IS3 is compressed to generate an elastic force that supports the weight of the aircraft. Due to the magnetorheological effect, the damping force generated by the flow is changed, thereby realizing a buffer strut with controllable damping. The current size is closed-loop controlled according to the motion state of the buffer strut. Under the controllable magnetic field generated by the electromagnetic control component 5, the magnetorheological fluid generates a large controllable damping force to alleviate the drop shock impact.

[0105] When the piston rod 4 contacts the floating piston 3, it pushes the floating piston 3 to compress the air chamber S2, and at the same time, the middle section 702 of the oil needle 7 penetrates into the through hole II201 of the inner tube 2, corresponding to the taxiing area after the aircraft takes off or the impact of landing, the magnetorheological fluid flows from the lower oil chamber S7 through the through hole II201 into the inner chamber S1, forming a smaller damping force working state determined by the variable cross-section design of the middle section 702, effectively isolating the vibration transmitted from the runway to the aircraft body through the buffer pillar, which will greatly reduce the natural frequency of the whole system. The gas in the inner chamber S1, the annular chamber IIS7 and the annular chamber IS3 continues to be compressed.

[0106] When the lower cut-off section 703 of the oil needle 7 penetrates the through hole II201, the through hole II201 is blocked. Since the gap between the lower cut-off section 703 and the through hole II201 of the inner cylinder 2 is very small, it is difficult for the magnetorheological fluid to pass through the through hole II201 at this time, and the compression of the buffer pillar will exceed the sliding area and enter the limit area. At this time, the air cavity S2 generates a greater elastic force due to the large compression to prevent the buffer pillar from generating excessive compression. The magnetorheological fluid enters the flow cavity S5 from the lower oil cavity S7 through the electromagnetic control component 5, flows into the side oil cavity S4 through the through hole V44 on the piston rod 4, and then flows into the annular cavity IS3 through the through hole IV431 on the outer curling edge 43, and finally flows into the inner cavity S1 through the through hole III203 on the inner cylinder 2. The gas in the inner cavity S1, the air cavity S2 and the annular cavity IS3 is further compressed. Under the controllable magnetic field generated by the electromagnetic control component 5, the magnetorheological fluid generates a large controllable damping force to relieve vibration.

[0107] When the piston rod 4 is restored, the compressed air chamber S2 pushes the floating piston 3 to move downward until the floating piston 3 is limited by the annular stopper 202. The floating piston 3 pushes the piston rod 4 to move downward, and the magnetorheological fluid flows from the inner chamber S1 through the through hole III203 into the annular chamber IS3, flows through the side oil chamber S4 and the flow chamber S5 in turn, and flows into the lower oil chamber S6 through the channel in the electromagnetic control component 5. When the middle section 702 of the oil needle 7 retreats to the through hole II201, the magnetorheological fluid flows from the inner chamber S1 through the through hole II201 into the lower oil chamber S6. When the upper stop section 701 of the oil needle 7 retreats to the circular through hole II201, the magnetorheological fluid flows from the inner chamber S1 through the through hole III203 into the annular chamber IS3, flows through the side oil chamber S4 and the flow chamber S5 in turn, and flows into the lower oil chamber S6 through the channel in the electromagnetic control component 5. When the upper cut-off section 701 of the oil needle 7 retracts to the initial state, the air pressures of the inner cavity S1, the air cavity S2, the annular cavity IS3 and the annular cavity IIS7 return to the initial state.

[0108] When the aircraft is stored in a warehouse, the buffer strut supports the aircraft and remains stationary for a long time. The aircraft's own weight compresses the buffer strut, and the middle section 702 of the oil needle 7 penetrates into the through hole II201 of the inner tube 2.

[0109] The magnetorheological fluid aircraft landing gear buffer strut disclosed in this embodiment can meet the various complex working conditions faced by aircraft landing. It can not only meet the aircraft landing shock requirements, but also effectively reduce the overall natural frequency, better isolate the vibration from the ground during taxiing, and solve the sedimentation problem of magnetorheological fluid.

[0110] Embodiment 3:

[0111] The main structure of this embodiment is the same as that of Embodiment 2. The electromagnetic control assembly 5 includes a positioning column 52 , a top cover 54 , an electromagnetic element 55 , a power device 56 and a rotor 57 .

[0112] The center of the upper end surface of the closed end 41 of the piston rod 4 is provided with a through hole VII413. The upper end surface of the closed end 41 is provided with a plurality of blind holes 412 on the same circumference. The closed end 41 is connected to the lower end of the piston rod 4 by threads.

[0113] There are a plurality of positioning posts 52 , and each positioning post 52 is correspondingly installed in a blind hole 412 of the closed end 41 .

[0114] The electromagnetic element 55 is located in the piston rod 4, and its lower end is fixed on the positioning column 52. An outer coil 551 is wound around the electromagnetic element 55.

[0115] The center of the end face of the top cover 54 has a circular hole II541. The end face of the top cover 54 is provided with a plurality of through holes VI542 on the same circumference. The top cover 54 is fixed to the upper end face of the stator 53. The upper end face of the top cover 54 has a circular annular boss 543. The lower end of the liner 6 is sleeved on the circular annular boss 543.

[0116] See also Figure 2 The rotor 57 is a cylinder, and the center of the end faces of both ends of the rotor 57 has a protruding shaft 571. The rotor 57 is located inside the electromagnetic element 55, and the protruding shaft 571 at the lower end is inserted into the through hole VII413 of the closed end 41, and the protruding shaft 571 at the upper end is inserted into the circular hole II541 of the top cover 54. The outer wall of the rotor 57 is processed with spiral ribs.

[0117] An inner channel is formed between the rotor 57 and the electromagnetic element 55. The inner channel is connected to the through hole VI542 of the top cover 54. An outer channel is formed between the electromagnetic element 55 and the piston rod 4. The lower end of the electromagnetic element 55 is supported by the positioning column 52, and a space connecting the inner channel and the outer channel is formed below the electromagnetic element 55.

[0118] The power device 56 is located outside the piston rod 4. The power device 56 is connected to the closed end 41 of the piston rod 4, and the output end of the power device 56 penetrates the through hole VII413 of the closed end 41 and is fixedly connected to the extended shaft 571 at the lower end of the rotor 57. The power device 56 is connected to an external power source.

[0119] When direct current is supplied to the outer coil 551 of the electromagnetic element 55, the outer coil 551 generates a uniformly distributed magnetic field in the outer channel. When the external power source drives the power device 56, the output end of the power device 56 drives the rotor 57 to rotate, and the rotor 57 drives the magnetorheological fluid to generate a rotating flow.

[0120] Embodiment 4:

[0121] The main structure of this embodiment is the same as that of Embodiment 3. The power device 56 is a rotary handle, and the output shaft of the rotary handle is manually driven to rotate, thereby driving the rotor 57 to rotate.

[0122] Embodiment 5:

[0123] The main structure of this embodiment is the same as that of Embodiment 3, and the electromagnetic element 55 is a magnetic yoke.

[0124] Embodiment 6:

[0125] The main structure of this embodiment is the same as that of the embodiment 3, and the positioning column 52 has a through hole VIII inside. The through hole VIII is connected to the blind hole 412 of the closed end 41. The bottom of the blind hole 412 is provided with a lead hole.

[0126] The lead wire 5511 of the outer coil 551 is led out through the through hole VIII on the positioning column 52, and passes through the lead hole at the bottom of the blind hole 412 to pass through the closed end 41 to connect to the external power supply.

[0127] Embodiment 7:

[0128] The main structure of this embodiment is the same as that of Embodiment 2. Furthermore, the floating piston 3 includes an upper ring 301 , a connecting portion 302 and a lower ring 303 .

[0129] The connecting portion 302 is connected between the upper ring 301 and the lower ring 303 .

[0130] An annular stop 202 is protruded on the outer wall of the inner cylinder 2. The four through holes III203 are all located below the annular stop 202. A sealing ring is installed on the outer wall of the upper ring 301. The upper ring 301 is stuck on the upper end of the annular stop 202 of the inner cylinder 2. The air cavity S2 is completely closed by the sealing ring.

[0131] The space between the upper ring 301 and the lower ring 303 is divided by the connecting portion 302, one side of which is the outer wall of the inner tube 2, and the other side is the inner wall of the outer tube 1. The space between the connecting portion 302 and the inner tube 2 is recorded as the annular cavity IIS8. The annular cavity IIS8 is connected to the inner cavity S1 through the through hole III203.

[0132] Embodiment 8:

[0133] The main structure of this embodiment is the same as that of Embodiment 7. Furthermore, the connecting portion 302 is cylindrical, and its outer wall is wrapped with a friction-reducing material.

[0134] Embodiment 9:

[0135] The main structure of this embodiment is the same as that of Embodiment 7. Furthermore, the annular limiting platform 202 is a circular annular flange.

[0136] There is a gap between the lower ring 303 and the inner wall of the inner cylinder 2 , and the gap is larger than the width of the annular stopper 202 . When the floating piston 3 slides upward, the lower ring 303 can pass through the annular stopper 202 .

[0137] Embodiment 10:

[0138] The main structure of this embodiment is the same as that of Embodiment 2. Furthermore, the upper cut-off section 701 and the through hole II201 are clearance-matched. The clearance between the upper cut-off section 701 and the through hole II201 is denoted as L. In this embodiment, L is 0.05 mm.

Claims

1. A magnetorheological fluid aircraft landing gear buffer strut, characterized in that: It comprises an outer cylinder (1), an inner cylinder (2), a floating piston (3), a piston rod (4), an electromagnetic control component (5), a liner (6) and an oil needle (7); The outer cylinder (1) has a closed upper end and a through hole I (101) is provided on the lower end surface; The inner cylinder (2) is located inside the outer cylinder (1), with its upper end connected to the closed portion of the upper end of the outer cylinder (1), and its lower end extending out of the through hole I (101) of the outer cylinder (1); A through hole II (201) is provided on the lower end surface of the inner cylinder (2); a plurality of layers of through holes III (203) are opened on the inner wall of the inner cylinder (2); The outer wall of the inner cylinder (2) and the inner wall of the outer cylinder (1) form a cavity S; the interior of the inner cylinder (2) is an inner cavity (S1); The floating piston (3) is installed between the inner cylinder (2) and the outer cylinder (1); the floating piston (3) divides the cavity S, and forms an air cavity (S2) above the floating piston (3); the floating piston (3) comprises an upper ring (301), a connecting portion (302) and a lower ring (303); The connecting portion (302) is connected between the upper ring (301) and the lower ring (303); An annular stop platform (202) is protruded on the outer wall of the inner cylinder (2); a plurality of layers of through holes III (203) are all located below the annular stop platform (202); a sealing ring is installed on the outer wall of the upper circular ring (301); the upper circular ring (301) is clamped on the upper end of the annular stop platform (202) of the inner cylinder (2); The space between the upper circular ring (301) and the lower circular ring (303) is divided by a connecting portion (302), one side of which is the outer wall of the inner cylinder (2), and the other side is the inner wall of the outer cylinder (1). The space between the connecting portion (302) and the inner cylinder (2) is recorded as an annular cavity II (S7); the annular cavity II (S7) is connected to the inner cavity (S1) through a through hole III (203); The piston rod (4) has an open upper end and a closed lower end (41); the upper open end of the piston rod (4) extends inwardly to form an inner curling edge (42) and extends outwardly to form an outer curling edge (43); The lower end of the inner cylinder (2) extends into the piston rod (4); the piston rod (4) extends from the through hole I (101) of the outer cylinder (1); The inner curl (42) and the outer curl (43) of the piston rod (4) separate the cavity S, and an annular cavity I (S3) is formed between the upper part of the inner curl (42) and the outer curl (43) and the floating piston (3), and a side oil cavity (S4) is formed between the lower part of the outer curl (43) and the lower end of the outer cylinder (1); a plurality of through holes IV (431) are provided on the outer curl (43); the side oil cavity (S4) is connected to the annular cavity I (S3) through the through hole IV (431); the annular cavity I (S3) is connected to the inner cavity (S1) through the through hole III (203); The electromagnetic control component (5) is mounted on the closed end (41) of the piston rod (4); the electromagnetic control component (5) generates a magnetic field when energized; the electromagnetic control component (5) comprises a positioning column (52), a top cover (54), an electromagnetic element (55), a power device (56) and a rotor (57); The center of the upper end surface of the closed end (41) of the piston rod (4) is provided with a through hole VII (413); the upper end surface of the closed end (41) is provided with a plurality of blind holes (412) on the same circumference; There are a plurality of positioning posts (52), and each positioning post (52) is correspondingly installed in a blind hole (412) of the closed end (41); The electromagnetic element (55) is located inside the piston rod (4), and its lower end is fixed on the positioning column (52); an outer coil (551) is wound around the electromagnetic element (55); The center of the end surface of the top cover (54) is provided with a circular hole II (541); the end surface of the top cover (54) is provided with a plurality of through holes VI (542) on the same circumference; the top cover (54) is fixed on the upper end surface of the stator (53); the upper end surface of the top cover (54) is provided with a circular boss (543); the lower end of the liner (6) is sleeved on the circular boss (543); The rotor (57) has a protruding shaft (571) at the center of the end surface at both ends; the rotor (57) is located inside the electromagnetic element (55), and the protruding shaft (571) at the lower end is inserted into the through hole VII (413) of the closed end (41), and the protruding shaft (571) at the upper end is inserted into the circular hole II (541) of the top cover (54); An inner channel is formed between the rotor (57) and the electromagnetic element (55); the inner channel is connected to the through hole VI (542) of the top cover (54); an outer channel is formed between the electromagnetic element (55) and the piston rod (4); the lower end of the electromagnetic element (55) is supported by a positioning column (52), and a space connecting the inner channel and the outer channel is formed below the electromagnetic element (55); The power device (56) is located outside the piston rod (4); the power device (56) is connected to the closed end (41) of the piston rod (4); the output end of the power device (56) penetrates into the through hole VII (413) of the closed end (41) and is fixedly connected to the protruding shaft (571) at the lower end of the rotor (57); the power device (56) is connected to an external power source; When direct current is supplied to the outer coil (551) of the electromagnetic element (55), the outer coil (551) generates a uniformly distributed magnetic field in the outer channel; when the external power source drives the power device (56), the output end of the power device (56) drives the rotor (57) to rotate, and the rotor (57) drives the magnetorheological fluid to generate a rotating flow; The liner (6) is located inside the piston rod (4), the upper end of which is sleeved on the inner cylinder (2) and in contact with the inner curling edge (42) of the piston rod (4), and the lower end of which is mounted on the electromagnetic control assembly (5); A flow chamber (S5) is formed between the outer wall of the liner (6) and the inner wall of the piston rod (4); the flow chamber (S5) is connected to the side oil chamber (S4) by opening a through hole V (44) on the inner wall of the piston rod (4); a lower oil chamber (S6) is formed in the liner (6); and a space connecting the lower oil chamber (S6) and the flow chamber (S5) is provided in the electromagnetic control component (5); The lower oil chamber (S6) and the inner chamber (S1) are filled with magnetorheological fluid; The oil needle (7) comprises an upper stop section (701) and a lower stop section (703) connected at both ends of the middle section (702); the cross sections of the upper stop section (701) and the lower stop section (703) are adapted to the through hole II (201); the cross section area of ​​the upper stop section (701) is larger than the cross section area of ​​the middle section (702); the oil needle (7) is located in the piston rod (4), the lower stop section (703) is mounted on the electromagnetic control assembly (5), and the upper stop section (701) penetrates into the through hole II (201) of the inner cylinder (2).

2. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The power device (56) is a motor or a rotating handle.

3. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The electromagnetic element (55) is a magnetic yoke.

4. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The positioning column (52) has a through hole VIII inside; the through hole VIII is connected to the blind hole (412) of the closed end (41); and a lead hole is provided at the bottom of the blind hole (412).

5. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The connecting portion (302) is cylindrical, and its outer wall is wrapped with friction-reducing material.

6. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The annular limiting platform (202) is a circular annular flange; There is a gap between the lower circular ring (303) and the inner wall of the inner cylinder (2), and the gap is greater than the width of the annular limiting platform (202).

7. The magnetorheological fluid aircraft landing gear buffer strut according to claim 1, characterized in that: The upper cut-off section (701) and the through hole II (201) are clearance-matched, and the clearance between the upper cut-off section (701) and the through hole II (201) is denoted as L, wherein 0<L≤0.1 mm.

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