Frame type undercarriage active frame positioner, airplane and method

Abstract

The invention provides a frame type landing gear active frame locator, an aircraft and a method. The active frame positioner of the frame type landing gear comprises an outer cylinder, a piston rod reciprocating in the outer cylinder, a valve shell installed on the outer cylinder and a plunger arranged in a rodless cavity of the outer cylinder and matched with the piston rod. A first flow channel, a second flow channel and a third flow channel are arranged in the valve shell, the first flow channel extends horizontally, one end of the first flow channel penetrates through the valve shell, the second flow channel is vertically connected between the first flow channel and the rodless cavity of the outer barrel, the third flow channel is vertically connected to the first flow channel, and one end of the third flow channel penetrates through the valve shell; an oil inlet pipe joint communicated with the rod cavity of the outer cylinder is arranged in the third flow channel; and an inflation valve communicated with the rodless cavity of the outer cylinder is arranged on the outer cylinder. Under the condition that an aircraft is driven by a hydraulic source, the frame can be positioned at a storage angle after an undercarriage is off the ground, and pitching vibration of the frame can be restrained in the aircraft taxiing process.

Description

Technical Field

[0001] This invention relates to the field of aircraft technology, and more particularly to an active frame positioner for a frame-type landing gear, an aircraft, and a method thereof. Background Technology

[0002] The chassis positioner is a component of the landing gear, connected to the landing gear struts and wheel carriers via hinges. It is responsible for actively controlling and stabilizing the attitude of the wheel carriers during the aircraft's dynamic movement.

[0003] Currently, many Airbus and Boeing wide-body passenger aircraft use chassis-type landing gear. Chassis-type landing gear for wide-body passenger aircraft is typically required to maintain a specific attitude when the landing gear is retracted, and to suppress the pitch oscillation of the chassis with the ground to a certain extent during aircraft taxiing. This requirement is the basic functional requirement of the chassis positioner.

[0004] Existing chassis positioners are particularly complex in structure and function, increasing the weight of the landing gear and introducing potential failure risks. Some solutions cannot achieve chassis positioning under hydraulic failure conditions, and others do not address the venting path during oil filling of the hydraulic chamber. Existing chassis-type landing gear structures include the following: (i) Patent publication number CN103032403A discloses an aircraft frame position control actuator, and patent publication number CN108791823A discloses an aircraft landing gear frame stabilization and buffer device and its control method. Both are similar, using a hydraulic power source and employing check valves, safety valves, control valves, damping valves, and actuators to achieve large-angle retraction and locking of the frame and dynamic buffering during taxiing. However, the electro-hydraulic valve group control and valve group damping scheme involves more components and more complex functions, inevitably increasing product weight and the number of failure points, thus reducing product reliability.

[0005] (ii) Patent publication number CN107588149A discloses a frame-type landing gear stabilizing damper, which is a passive stabilizing damper. Its power source is the pressure of a sealed oil-gas chamber. It can maintain a neutral position when there is no external load and has a certain buffering function under specific operating conditions. However, it does not consider overcoming external loads in the neutral position, and the damping in the oil-gas mixing chamber cannot generate effective damping when the oil level does not exceed the damping orifice.

[0006] (iii) Patent publication number CN216611589U discloses an aircraft landing gear frame stabilization buffer device. Its frame buffer mechanism includes a first buffer layer, a second buffer layer and a third buffer layer. It uses springs, shock absorbers and cylinders to simultaneously dampen shocks. It is not a common landing gear arrangement. Its structure is complex and the statically determinate and statically indeterminate forces are complicated. It is suitable for UAVs or small aircraft with low safety requirements, but not suitable for large aircraft.

[0007] (iv) Patent publication number CN115234537A discloses a highly reliable integrated frame stabilization and buffer actuation device, which controls the attitude adjustment of the frame simultaneously with active and passive control. Its actuation cylinder contains four functional chambers: dual floating pistons, dual air chambers, dual oil chambers, and no leakage compensation. The pressure balance and the positional relationship of the floating pistons are very complex. The frame stabilizer state is too complex and there are too many failure risk factors, making it unsuitable for installation and use on civil aviation passenger aircraft with high safety requirements.

[0008] (v) Patent publication number CN117432738A discloses an unloading valve and a frame stabilizing buffer actuation device. Its main invention is an unloading valve, which can control the attitude adjustment of the frame simultaneously with active and passive control. Its actuation cylinder contains three functional chambers: a single air chamber and a double oil chamber. Its functions are more numerous and complex, requiring a reversing valve for control, and there are too many factors that could lead to failure.

[0009] (vi) Patent publication number CN117703984A discloses a frame stabilizing damper, which controls the attitude adjustment of the frame simultaneously in active and passive modes. Its actuator contains three functional chambers: a single air chamber and a double oil chamber. The oil inlet and outlet of the double oil chamber are designed with a one-way valve, a damping valve, and a safety valve. Its functions are more numerous and complex, requiring a reversing valve for control, and there are too many factors that could lead to failure.

[0010] (vii) Patent publication number CN119687138A discloses a self-contained frame stabilizing damper, and patent publication number CN116215846A discloses a frame-type landing gear passive frame positioner and oil filling method. Both are passive stabilizing dampers, and their power source is the pressure of their sealed oil and gas chamber. They can maintain a neutral position when there is no external load, but neither of them has a leakage compensation device. Their leakage will change the position of the floating piston, thereby bringing the risk of functional loss. Summary of the Invention

[0011] The purpose of this invention is to provide an active chassis positioner for chassis-type landing gear, an aircraft, and a method that, under the condition of being driven by the aircraft's hydraulic power source, can both position the chassis at the retracted angle after the landing gear leaves the ground and suppress the pitch vibration of the chassis during the aircraft's taxiing process.

[0012] The technical solution of the present invention is: an active frame positioner for a frame-type landing gear, comprising an outer cylinder, a piston rod reciprocating in the outer cylinder, a valve housing mounted on the outer cylinder, and a plunger disposed in the rodless cavity of the outer cylinder and cooperating with the piston rod. The valve housing is provided with a first flow channel extending horizontally and having one end penetrating the valve housing, a second flow channel vertically connected between the first flow channel and the rodless cavity of the outer cylinder, and a third flow channel vertically connected to the first flow channel and having one end penetrating the valve housing. The first flow channel is provided with a return oil port connector, and the third flow channel is provided with an oil inlet connector communicating with the rod cavity of the outer cylinder. The outer cylinder is provided with an inflation valve communicating with the rodless cavity of the outer cylinder.

[0013] Preferably, the return port pipe joint is provided with a safety valve core and a safety valve spring for resetting the safety valve core; the inlet port pipe joint is provided with a one-way valve core and a one-way valve spring for resetting the one-way valve core.

[0014] Preferably, the plunger includes a plunger rod and a plunger seat, one end of the plunger rod is engaged with the plunger rod, the other end of the plunger rod is connected to the plunger seat, and the plunger seat is engaged with the outer cylinder.

[0015] Preferably, an atmospheric cavity is formed between the plunger seat and the outer cylinder, and a plug is provided on the side wall of the outer cylinder. The plug has an exhaust hole, which is connected to the atmospheric cavity and the atmosphere.

[0016] Preferably, the plunger rod has a plurality of radially penetrating second oil passages arranged along the axial direction, and the plunger rod has a plurality of axially penetrating first oil passages evenly distributed around the end of the plunger rod that extends into the piston rod, and the first oil passages and second oil passages form an oil channel.

[0017] Preferably, a damping ring is connected to the end of the piston rod, the damping ring is adapted between the outer cylinder and the plunger rod, and the damping ring is provided with a damping hole that runs through the outer cylinder axially.

[0018] Preferably, the damping holes are evenly distributed circumferentially on the damping ring.

[0019] The present invention also provides an aircraft including landing gear, the landing gear including the above-described active frame positioner for frame-type landing gear.

[0020] The present invention also provides a method for operating a frame-type landing gear active frame positioner, using the aforementioned aircraft, comprising: After the aircraft takes off, the piston rod extends, and the piston rod drives the damping ring to move to the end of the plunger; at this time, the tensile load on the frame positioner is P0·π·(D 2 -d 2 ) / 4, the compressive load is P0·π·d 2 / 4, where P0 is the aircraft system pressure, D is the inner diameter of the outer cylinder, and d is the outer diameter of the piston rod; When the aircraft is taxiing or stopping, the piston rod retracts and drives the damping ring to slide along the plunger. The oil in the rodless chamber flows to the rod chamber through the damping hole on the damping ring. When the oil pressure in the rod chamber exceeds the set value, the rod chamber is depressurized, so that the oil flows back through the return oil port connector until the aircraft stops. When the aircraft is taxiing or stationary, if the rear wheel of the aircraft bleeds, the piston rod retracts further; if the front wheel of the aircraft bleeds, the plunger and piston rod extend together along the outer cylinder.

[0021] The present invention also provides a method for filling an active frame positioner for a chassis-type landing gear with oil, using the aforementioned active frame positioner for a chassis-type landing gear, comprising: Oil filling steps under conditions where hydraulic oil filling equipment is available: 1) Place the frame positioner vertically with the piston rod facing down; 2) Connect the oil inlet pipe connector and the air inlet valve to the hydraulic oil filling equipment respectively, wherein the oil inlet pipe connector is connected to the oil inlet end and the air inlet valve is connected to the oil return end; 3) Fill the outer cylinder with oil through the oil inlet pipe joint. During this process, the air in the outer cylinder is discharged through the air filling valve. The filling is completed when no more air is discharged from the oil return end. Oil filling steps without hydraulic filling equipment: 1) Tilt the frame positioner so that the piston rod is facing down; 2) Remove the inflation valve, use a syringe to fill the outer cylinder with oil, and shake the frame positioner to make the air inside the outer cylinder float up; 3) After filling, place the frame positioner horizontally, shake the frame positioner to expel air, and then continue to add oil. 4) After the oil filling is completed, install the inflation valve to complete the oil filling.

[0022] Compared with related technologies, the beneficial effects of the present invention are as follows: 1. The chassis positioner of the present invention does not include active retraction control function. After the landing gear leaves the ground, it can reach the retracted posture without manual control operation. Both tension and compression damping are achieved through damping rings with support and damping functions. It does not contain electronic control equipment, has fewer parts, and has a simpler principle. Second, this invention uses a hydraulic power source, with the pressure of the aircraft hydraulic power source as the power source, which effectively reduces the functional loss caused by seal leakage; and can overcome the aerodynamic load during the landing gear retraction and extension process when in the neutral position; the damping ring with damping holes has oil on both sides, and has damping when stretched or compressed; Third, the present invention uses a combination of a one-way valve and a safety valve, which can maintain the position of the chassis in the event of hydraulic failure and prevent the tires from getting stuck in the landing gear bay when the landing gear is deployed in an emergency. Fourth, this invention utilizes the oil inlet and air valve of the frame positioner to achieve oil filling circulation, which can effectively expel air from the actuator cylinder. Attached Figure Description

[0023] Figure 1 A schematic diagram of the internal structure of the active frame positioner for frame-type landing gear provided by the present invention; Figure 2 for Figure 1 Top view; Figure 3 for Figure 1 An enlarged schematic diagram of the valve housing; Figure 4 for Figure 1 An enlarged schematic diagram of the plug in the middle; Figure 5 This is a schematic diagram of the damping ring structure; Figure 6 This is a frontal projection diagram of the plunger rod; Figure 7 This is a side projection diagram of the plunger rod; Figure 8 A schematic diagram illustrating the functional principle of the active frame positioner for a frame-type landing gear provided for the invention. Figure 9 A schematic diagram of the oil filling status of the frame positioner under conditions where a hydraulic oil filling device is available; Figure 10 A schematic diagram of the oil filling status of the frame positioner under conditions where there is no hydraulic oil filling equipment; Figure 11 This is a schematic diagram showing the status of the vehicle frame locator after the aircraft has taken off the ground. Figure 12 A schematic diagram showing the status of the chassis positioner when the aircraft is taxiing or parked. Figure 13 This is a schematic diagram showing the status of the chassis positioner when the rear wheel of an aircraft experiences a deflation. Figure 14 This is a schematic diagram showing the status of the chassis positioner when the aircraft's front wheel experiences a flat tire.

[0024] In the attached diagram: 1. Piston rod; 2. Outer cylinder; 3. End cap; 4. Damping ring; 41. Damping hole; 5. Cover plate; 6. Plug; 61. Exhaust port; 7. Inflation valve; 8. Seal; 9. Valve body; 91. First flow channel; 92. Second flow channel; 93. Third flow channel; 11. Oil inlet pipe connector; 12. One-way valve core; 13. One-way valve spring; 14. Oil return pipe connector; 15. Safety valve spring; 16. Safety valve core; 17. Bolt; 20. Plunger; 21. Plunger seat; 22. Plunger rod; 221. First shoulder; 222. Second shoulder; 2201. First oil passage hole; 2202. Second oil passage hole; 23. Nut. Detailed Implementation

[0025] 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.

[0026] like Figure 1 , Figure 3 As shown, the active frame positioner for a frame-type landing gear provided in this embodiment includes a piston rod 1, an outer cylinder 2, an end cap 3, a damping ring 4, a cover plate 5, a plug 6, an inflation valve 7, a seal 8, a valve body 9, an oil inlet pipe connector 11, a one-way valve core 12, a one-way valve spring 13, an oil return pipe connector 14, a safety valve spring 15, a safety valve core 16, a bolt 17, and a plunger 20.

[0027] One end of the piston rod 1 extends into the outer cylinder 2, forming a rod-side cavity and a rodless cavity inside the outer cylinder 2. The cover plate 5 seals the outer cylinder 2, and the piston rod 1 passes through the cover plate 5. An end cap 3 is disposed between the outer cylinder 2 and the piston rod 1, positioned close to the cover plate 5. A sealing element 8 is provided on the inner ring of the end cap 3, abutting against the piston rod 1, and a sealing element 8 is provided on the outer ring of the end cap 3, abutting against the inner wall of the outer cylinder 2, thereby forming a sealed oil cavity inside the actuating cylinder (outer cylinder 2).

[0028] A damping ring 4 is fitted onto the end of the piston rod 1 that extends into the outer cylinder 2. The damping ring 4 slides against the inner wall of the outer cylinder 2, and reciprocates along with the piston rod 1. Figure 1 , Figure 5 As shown, the damping ring 4 has multiple damping holes 41 arranged circumferentially along the axial direction of the outer cylinder 2. The damping holes 41 connect the rod-side cavity and the rodless cavity, making the actuating cylinder oil cavity a single cavity.

[0029] like Figure 1As shown, the plunger 20 includes a plunger seat 21 and a plunger rod 22. One end of the plunger rod 22 has a first shoulder 221. The plunger seat 21 is fitted onto the plunger rod 22, and both ends of the plunger seat 21 are respectively limited by a nut 23 and the first shoulder 221. A sealing element 8 is embedded in the plunger rod 22, which contacts the plunger seat 21. Figure 1 , Figure 6 , Figure 7 As shown, the other end of the plunger rod 22 is provided with a second shoulder 222. The plunger rod 22 extends into the piston rod 1, and the second shoulder 222 is positioned on the damping ring 4 on the side away from the plunger seat 21. The second shoulder 222 allows the piston rod 1 to move along the plunger rod 22 when compressed, and to drive the plunger 20 to move together when the piston rod 1 extends. The plunger seat 21 mates with the outer cylinder 2, and a sealing element 8 that contacts the outer cylinder 2 is embedded on the outer circumference of the plunger seat 21. The sealing element 8 can be an O-ring.

[0030] like Figure 1 , Figure 6 As shown, the plunger rod 22 has multiple radially penetrating second oil passages 2202 arranged axially, and multiple axially penetrating first oil passages 2201 evenly distributed circumferentially on the second shoulder 222 of the plunger rod 22. The first oil passages 2201 and the second oil passages 2202 form an oil passage. A channel is provided in the plunger rod 22, which communicates with the interior of the piston rod 1, and the multiple second oil passages 2202 communicate with this channel. The damping ring 4 is clearance-fitted with the plunger rod 22, and this clearance connects the rodless chamber, the first oil passages 2201, and the interior of the piston rod 1. The sealing fit between the plunger seat 21 and the outer cylinder 2, and the fit between the plunger rod 22 and the piston rod 1, form two-point support, ensuring smooth sliding of the plunger 20.

[0031] like Figure 1 As shown, the outer cylinder 2 is sequentially provided with a plug 6, an inflation valve 7, and a valve body 9. The plug 6 and the inflation valve 7 are located near the rodless cavity, with the plug 6 located closer to the end of the plunger seat 21. The plug 6 has an exhaust hole 61 (e.g., Figure 4 As shown, the atmospheric cavity enclosed by the plunger seat 21 and the outer cylinder 2 is connected to the atmosphere through the vent hole 61, thus avoiding affecting the pressure inside the frame positioner. The vent hole 61 can be T-shaped, with the vertical channel communicating with the outer cylinder 2 and the horizontal channel communicating with the outside atmosphere, which can reduce the risk of blockage.

[0032] The inflatable valve 7 is detachably connected to the outer cylinder 2. For example... Figure 2 As shown, the valve housing 9 is mounted to the outer cylinder 2 by bolts 17. Figure 1 , Figure 3As shown, the valve housing 9 has a first flow channel 91 extending horizontally and having one end penetrating the valve housing 9, a second flow channel 92 vertically connected between the first flow channel 91 and the rodless cavity of the outer cylinder 2, and a third flow channel 93 vertically connected to the first flow channel 91 and having one end penetrating the valve housing 9. The first flow channel 91 has a return port connector 14, which contains a safety valve core 16 and a safety valve spring 15 for resetting the safety valve core 16. The third flow channel 93 has an inlet connector 11 communicating with the rod cavity of the outer cylinder 2. The inlet connector 11 contains a one-way valve core 12 and a one-way valve spring 13 for resetting the one-way valve core 12. The end of the valve housing 9 forming the second flow channel 92 extends into the interior of the outer cylinder 2, and a sealing element 8 is provided between them.

[0033] The valve housing 9 mounted on the outer cylinder 2 contains a valve assembly, which controls the inlet and outlet oil flow of the actuator cylinder when the hydraulic power source is operating. The valve assembly includes a check valve at the inlet and a safety valve at the outlet. The check valve consists of a housing, a valve core, and a spring; the valve core closes the inlet passage under the force of the spring. The safety valve also consists of a housing, a valve core, and a spring; the valve core closes the outlet oil flow under the force of the spring.

[0034] The present invention also provides a method for filling an active frame positioner for a chassis-type landing gear with oil, using the aforementioned active frame positioner for a chassis-type landing gear, comprising: like Figure 9 As shown, the oil filling steps are as follows, provided that a hydraulic oil filling device is available: 1) Place the frame locator vertically with piston rod 1 facing down; 2) Connect the oil inlet pipe joint 11 and the air inlet valve 7 to the hydraulic oil filling equipment respectively, wherein the oil inlet pipe joint 11 is connected to the oil inlet end and the air inlet valve 7 is connected to the oil return end. 3) Fill the outer cylinder 2 with oil through the oil inlet pipe joint 11 (with sealing cap) at a pressure of about 2MPa. During this process, the air in the outer cylinder 2 is discharged from the air filling valve 7. The filling is completed when no air is discharged from the return end. like Figure 10 As shown, the oil filling steps are as follows under conditions without hydraulic oil filling equipment: 1) Tilt the frame locator (5-10° to the vertical direction), with piston rod 1 facing down and inflation valve 7 facing up; 2) Remove the inflation valve 7, use a syringe to fill the outer cylinder 2 with oil, and shake the frame positioner while filling with oil to make the air inside the outer cylinder 2 float up; 3) After filling, place the frame positioner horizontally, shake the frame positioner to expel air, and then continue to add oil. 4) After the oil filling is completed, install the air inflator valve 7 to complete the oil filling.

[0035] The present invention also provides an aircraft including landing gear, the landing gear including the above-described active frame positioner for frame-type landing gear.

[0036] The chassis positioner can operate in three positions: initial position, piston rod extended position, and piston rod compressed position. The initial position is the landing gear retracted position, which is the active approach position of the chassis positioner. The other two positions are passive approach positions. Its functional principle is as follows: Figure 8 As shown.

[0037] Specifically, the present invention also provides a method for operating a frame-type landing gear active frame positioner, using the aforementioned aircraft, comprising: like Figure 11 As shown, after the aircraft takes off, piston rod 1 extends, and piston rod 1 drives damping ring 4 to move to the end of plunger 20; at this time, the tensile load borne by the frame positioner is P0·π·(D 2 -d 2 ) / 4, the compressive load is P0·π·d 2 / 4, where P0 is the aircraft system pressure, D is the inner diameter of outer cylinder 2, and d is the outer diameter of piston rod 1. The chassis positioner must withstand external wind loads to prevent the landing gear from failing to retract into the cabin due to the chassis not being in the designated position. During design, reasonable pressure and cross-sectional dimensions can be selected based on the aircraft's operating envelope and landing gear structure to meet usage requirements. For example, the system pressure P0 of a civil wide-body passenger aircraft is typically 5000 psi. With D=40mm and d=20mm, it can withstand a tensile load of approximately 32.5kN and a ballast load of 10.8kN.

[0038] like Figure 12 As shown, during aircraft taxiing or parking, piston rod 1 retracts, causing damping ring 4 to slide along plunger 20. Oil in the rodless chamber flows through damping hole 41 on damping ring 4 to the rod chamber. This dissipates pitch energy during aircraft taxiing and suppresses pitch vibration of the chassis. The safety valve opens at pressure P1. When piston rod 1 extends or retracts too quickly, causing pressure buildup, to prevent damage to the chassis positioner, pressure is released from the actuator when the pressure exceeds P1, allowing oil to flow back through the safety valve. Thus, the first oil passage 2201 and the second oil passage 2202 on plunger rod 22 form a rapid oil flow channel during piston rod 1 movement.

[0039] During aircraft taxiing or parking, if the chassis positioner experiences a malfunction such as air leakage at the rear wheel (depending on the chassis positioner's location, the rear wheel is positioned at the front of the chassis with reference to the chassis positioner), the piston rod 1 will retract further compared to the taxiing state (e.g., ...). Figure 13 (As shown). In the event of a failure such as a deflated nose wheel, compared to the retracted state, piston rod 1 extends and pulls plunger 20 to extend along the outer cylinder 2 (as shown). Figure 14 (As shown).

[0040] When the aircraft is off the ground, if the hydraulic power source fails, the one-way valve core 12 closes the oil inlet under the action of the one-way valve spring 13, the safety valve core 16 works normally, and the frame positioner can still maintain the frame attitude to meet the emergency release function of the landing gear and avoid accidents.

[0041] 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 frame-type landing gear active frame positioner, comprising an outer cylinder (2) and a piston rod (1) reciprocating within the outer cylinder (2), characterized in that, It also includes a valve housing (9) installed on the outer cylinder (2) and a plunger (20) located in the rodless cavity of the outer cylinder (2) and cooperating with the piston rod (1). The valve housing (9) is provided with a first flow channel (91) extending horizontally and having one end through the valve housing (9), a second flow channel (92) vertically connected between the first flow channel (91) and the rodless cavity of the outer cylinder (2), and a third flow channel (93) vertically connected to the first flow channel (91) and having one end through the valve housing (9). The first flow channel (91) is provided with a return oil port connector (14), and the third flow channel (93) is provided with an oil inlet connector (11) communicating with the rod cavity of the outer cylinder (2). The outer cylinder (2) is provided with an inflation valve (7) communicating with the rodless cavity of the outer cylinder (2).

2. The active frame positioner for chassis-type landing gear according to claim 1, characterized in that, The return port pipe joint (14) is provided with a safety valve core (16) and a safety valve spring (15) for resetting the safety valve core (16); the inlet port pipe joint (11) is provided with a one-way valve core (12) and a one-way valve spring (13) for resetting the one-way valve core (12).

3. The active frame positioner for chassis-type landing gear according to claim 1, characterized in that, The plunger (20) includes a plunger rod (22) and a plunger seat (21). One end of the plunger rod (22) is engaged with the plunger rod (22), and the other end of the plunger rod (22) is connected to the plunger seat (21). The plunger seat (21) is engaged with the outer cylinder (2).

4. The active frame positioner for chassis-type landing gear according to claim 3, characterized in that, An atmospheric cavity is formed between the plunger seat (21) and the outer cylinder (2). A plug (6) is provided on the side wall of the outer cylinder (2). An exhaust hole (61) is provided inside the plug (6). The exhaust hole (61) is connected to the atmospheric cavity and the atmosphere.

5. The active frame positioner for chassis-type landing gear according to claim 3, characterized in that, The plunger rod (22) is provided with a plurality of radially penetrating second oil passage holes (2202) along the axial direction. The plunger rod (22) extends into the piston rod (1) and is provided with a plurality of axially penetrating first oil passage holes (2201) evenly distributed around the circumference. The first oil passage holes (2201) and the second oil passage holes (2202) form an oil passage.

6. The active frame positioner for chassis-type landing gear according to claim 3, characterized in that, The piston rod (1) is connected to a damping ring (4) at its end. The damping ring (4) is adapted between the outer cylinder (2) and the plunger rod (22). The damping ring (4) is provided with a damping hole (41) that runs through the outer cylinder (2) axially.

7. The active frame positioner for chassis-type landing gear according to claim 6, characterized in that, The damping holes (41) are evenly distributed circumferentially on the damping ring (4).

8. An aircraft, comprising landing gear, characterized in that, The landing gear includes an active frame positioner for a frame-type landing gear as described in any one of claims 1-7.

9. A method for operating a frame-type landing gear active frame positioner, using the aircraft as described in claim 8, characterized in that, include: After the aircraft takes off, the piston rod (1) extends, and the piston rod (1) drives the damping ring (4) to move to the end of the plunger (20); at this time, the tensile load borne by the frame positioner is P0·π·(D 2 -d 2 ) / 4, the compressive load is P0·π·d 2 / 4, where P0 is the aircraft system pressure, D is the inner diameter of the outer cylinder (2), and d is the outer diameter of the piston rod (1); When the aircraft is taxiing or stopping, the piston rod (1) retracts and the piston rod (1) drives the damping ring (4) to slide along the plunger (20). The oil in the rodless chamber flows to the rod chamber through the damping hole (41) on the damping ring (4). When the oil pressure in the rod chamber exceeds the set value, the rod chamber is depressurized so that the oil flows back through the return oil port connector (14) until the aircraft stops. When the aircraft is taxiing or stopped, if the rear wheel of the aircraft is deflated, the piston rod (1) will retract further; if the front wheel of the aircraft is deflated, the plunger (20) and the piston rod (1) will extend together along the outer cylinder (2).

10. A method for filling an active frame positioner for a chassis-type landing gear with oil, comprising using the active frame positioner for a chassis-type landing gear as described in any one of claims 1-7, characterized in that, include: Oil filling steps under conditions where hydraulic oil filling equipment is available: 1) Place the frame locator vertically with the piston rod (1) facing down; 2) Connect the oil inlet pipe joint (11) and the air valve (7) to the hydraulic oil filling equipment respectively. The oil inlet pipe joint (11) is connected to the oil inlet end, and the air valve (7) is connected to the oil return end. 3) Fill the outer cylinder (2) with oil through the oil inlet pipe joint (11). During this process, the air in the outer cylinder (2) is discharged through the air filling valve (7); until no gas is discharged from the oil return end, the oil filling is completed. Oil filling steps without hydraulic filling equipment: 1) Place the frame locator at an angle with the piston rod (1) facing down; 2) Remove the inflation valve (7), use a syringe to fill the outer cylinder (2) with oil, and shake the frame positioner to make the air inside the outer cylinder (2) float up; 3) After filling, place the frame positioner horizontally, shake the frame positioner to expel air, and then continue to add oil. 4) After the oil filling is completed, install the inflation valve (7) to complete the oil filling.

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