Helicopter undercarriage folding and unfolding system and helicopter undercarriage

Abstract

The invention provides a helicopter undercarriage folding and unfolding system and a helicopter undercarriage. The helicopter undercarriage folding and unfolding system comprises a buffer (9) and a folding and unfolding oil cylinder (3). Wherein a retractable piston (10) and a piston rod (8) are arranged in the buffer (9), the retractable piston (10) divides the interior of the buffer (9) into a left cavity (12) and a right cavity (11), and the piston rod (8) is connected with an airplane wheel or a rocker arm; the right cavity (11) is used for receiving oil liquid of a hydraulic system, and under the driving of the oil liquid of the hydraulic system, the retractable piston (10) moves to drive the piston rod (8) to move; a piston (2) is arranged in the retractable oil cylinder (3), an upper cavity (1) and a lower cavity (4) are formed, the upper cavity (1) is communicated with a left cavity (12) of the buffer (9) and used for storing oil transferred when the buffer (9) is retracted, and the lower cavity (4) is used for receiving oil of a hydraulic system; the sectional area of the lower cavity (4) is smaller than that of the upper cavity (1).

Description

Technical Field

[0001] The present invention relates to the field of helicopter landing gears, and more particularly to a helicopter landing gear retraction system and a helicopter landing gear. Background Art

[0002] In order to reduce air resistance during flight, increase the range, and improve economy, civil medium and large transport helicopters often adopt retractable landing gears.

[0003] Generally, during flight in the air, the landing gear can be retracted and hidden inside the fuselage, and before landing, the landing gear can be lowered to ensure the safe landing of the helicopter. For helicopters using hydraulic energy as the secondary energy, hydraulic drive is usually used to retract and lower the landing gear.

[0004] For strut-type landing gears, retraction and extension actuators can be installed for retraction and extension. One end of the retraction and extension actuator is installed on the fuselage structure, and the other end is connected to the buffer. The actuator usually requires a large retraction and extension space and increases additional weight. For helicopters with a compact structure, there is not enough retraction and extension space to arrange a landing gear with a retraction and extension actuator installed;

[0005] For rocker-type landing gears, it is difficult to retract and extend them by installing retraction and extension actuators due to structural limitations;

[0006] In summary, the helicopter landing gear retraction system needs to solve the following two problems:

[0007] 1. Retract and extend the landing gear in a small space;

[0008] 2. A retraction and extension solution applicable to rocker-type landing gears. Summary of the Invention

[0009] The present invention provides a helicopter landing gear retraction system and a helicopter landing gear, which solve the problem that the existing landing gear retraction system cannot be applied to aircraft with structural limitations.

[0010] In a first aspect of the present invention, a helicopter landing gear retraction system is provided, including: a buffer 9 and a retraction and extension oil cylinder 3; wherein,

[0011] A retraction and extension piston 10 and a piston rod 8 are arranged inside the buffer 9. The retraction and extension piston 10 divides the inside of the buffer 9 into a left chamber 12 and a right chamber 11, and the piston rod 8 is connected to the wheel or the rocker;

[0012] The right chamber 11 is used to receive the oil fluid of the hydraulic system. Driven by the oil fluid of the hydraulic system, the retraction and extension piston 10 moves, driving the piston rod 8 to move;

[0013] A piston 2 is arranged in the retractable oil cylinder 3, forming an upper chamber 1 and a lower chamber 4. The upper chamber 1 is communicated with the left chamber 12 of the buffer 9 for storing the oil transferred when the buffer 9 is retracted, and the lower chamber 4 is used to receive the oil of the hydraulic system;

[0014] The cross-sectional area of the lower chamber 4 is smaller than that of the upper chamber 1.

[0015] Optionally, the cross-sectional area of the lower chamber 4 is half of that of the upper chamber 1.

[0016] Optionally, the helicopter landing gear retractable system further includes: a first pilot-operated check valve 15, a second pilot-operated check valve 14, and a third pilot-operated check valve 7;

[0017] The control end of the first pilot-operated check valve 15, the control end of the second pilot-operated check valve 14, and the on-end of the third pilot-operated check valve 7 are connected to the retraction supply port 6 of the hydraulic system;

[0018] The control end of the third pilot-operated check valve 7 and the lower chamber 4 of the retractable oil cylinder 3 are connected to the extension supply port 5 of the hydraulic system;

[0019] The on-end of the first pilot-operated check valve 15 is connected to the upper chamber 1 of the retractable oil cylinder 3, the off-end of the first pilot-operated check valve 15 is connected to the on-end of the second pilot-operated check valve 14, and the off-end of the second pilot-operated check valve 14 is connected to the left chamber 12 of the buffer 9;

[0020] The off-end of the third pilot-operated check valve 7 is connected to the right chamber 11 of the buffer 9.

[0021] Optionally, the helicopter landing gear retractable system further includes: a pressure sensor 13;

[0022] The pressure sensor 13 is used to monitor the oil pressure P in the left chamber 12 of the buffer 9.

[0023] Optionally, when P≥the first preset pressure P1, a first indication signal is generated; the first indication signal is used to indicate that a normal landing can be made and the landing gear does not need to be inspected after landing;

[0024] When P1>P≥the second preset pressure P2, a second indication signal is generated, and the second indication signal is used to indicate that the landing sinking speed needs to be less than the preset speed and the landing gear is inspected after landing;

[0025] When P<P2, a third indication signal is generated, and the third indication signal is used to indicate that external facilities are needed to complete the landing and the landing gear is inspected after landing;

[0026] Wherein, the first preset pressure P1 is greater than the second preset pressure P2.

[0027] In the second aspect of the present invention, a helicopter landing gear is provided, which adopts the helicopter landing gear retractable system described in any one of the first aspects.

[0028] The present invention provides a helicopter landing gear retraction system and a helicopter landing gear, enabling the helicopter to retract and extend the landing gear more safely and being applicable to helicopters with restricted structures.

[0029] 1) The volume of hydraulic fluid required for the present invention to lower the landing gear is half of the volume of hydraulic fluid required to retract the landing gear.

[0030] 2) The present invention isolates the hydraulic fluid inside the landing gear from the hydraulic fluid of the retraction and extension system.

[0031] 3) The present invention uses hydraulic control check valves as the upper and lower locks.

[0032] 4) The lower lock of the present invention is designed with dual redundancy.

[0033] 5) The present invention uses pressure sensors to monitor the internal cavity pressure of the landing gear.

[0034] 6) The present invention generates an indication signal to prompt the landing risk. Description of the Drawings

[0035] Figure 1 It is a schematic diagram of the composition and principle of the helicopter landing gear retraction system provided by the present invention.

[0036] Description of the Reference Numerals:

[0037] 1. Upper cavity of the retraction and extension cylinder; 2. Piston of the retraction and extension cylinder; 3. Retraction and extension cylinder; 4. Lower cavity of the retraction and extension cylinder; 5. Lower supply port; 6. Retraction supply port; 7. Third hydraulic control check valve; 8. Buffer piston rod; 9. Buffer; 10. Retraction and extension piston; 11. Right cavity of the buffer; 12. Left cavity of the buffer; 13. Pressure sensor; 14. Second hydraulic control check valve; 15. First hydraulic control check valve. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0039] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present invention by showing examples of the present invention. The present invention is in no way limited to any specific arrangements and methods set forth below, but covers any improvements, substitutions, and modifications of structures, methods, and devices without departing from the spirit of the present invention. In the drawings and the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the present invention.

[0040] It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other, and the various embodiments may be referenced and cited with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] The present invention will be further described in detail below in combination with the embodiments and the drawings, but the embodiments of the present invention are not limited thereto.

[0042] As Figure 1 shown, the present invention provides a helicopter landing gear retraction system, including: a buffer 9 and a retraction cylinder 3; wherein,

[0043] A retraction piston 10 and a piston rod 8 are arranged in the buffer 9. The retraction piston 10 divides the inside of the buffer 9 into a left chamber 12 and a right chamber 11. The piston rod 8 is connected to the wheel or the rocker arm;

[0044] The right chamber 11 is used to receive the oil fluid of the hydraulic system. Driven by the oil fluid of the hydraulic system, the retraction piston 10 moves, driving the piston rod 8 to move;

[0045] A piston 2 is arranged in the retraction cylinder 3, forming an upper chamber 1 and a lower chamber 4. The upper chamber 1 is communicated with the left chamber 12 of the buffer 9 and is used to store the oil fluid transferred when the buffer 9 is retracted. The lower chamber 4 is used to receive the oil fluid of the hydraulic system;

[0046] The cross-sectional area of the lower chamber 4 is smaller than the cross-sectional area of the upper chamber 1.

[0047] Optionally, the cross-sectional area of the lower chamber 4 is half of the cross-sectional area of the upper chamber 1.

[0048] Optionally, the helicopter landing gear retraction system further includes: a first hydraulic control check valve 15, a second hydraulic control check valve 14, and a third hydraulic control check valve 7;

[0049] The control end of the first hydraulic control check valve 15, the control end of the second hydraulic control check valve 14, and the connection end of the third hydraulic control check valve 7 are connected to the retraction pressure supply port 6 of the hydraulic system;

[0050] The control end of the third pilot-operated check valve 7 is connected to the lowering supply port 5 of the hydraulic system through the lower chamber 4 of the retractable cylinder 3.

[0051] The conducting end of the first pilot-operated check valve 15 is connected to the upper chamber 1 of the retractable cylinder 3. The cut-off end of the first pilot-operated check valve 15 is connected to the conducting end of the second pilot-operated check valve 14. The cut-off end of the second pilot-operated check valve 14 is connected to the left chamber 12 of the buffer 9.

[0052] The cut-off end of the third pilot-operated check valve 7 is connected to the right chamber 11 of the buffer 9.

[0053] Optionally, the helicopter landing gear retraction system further includes: a pressure sensor 13;

[0054] The pressure sensor 13 is used to monitor the oil pressure P in the left chamber 12 of the buffer 9.

[0055] Optionally, when P≥the first preset pressure P1, a first indication signal is generated; the first indication signal is used to indicate that a normal landing can be made and the landing gear does not need to be inspected after landing;

[0056] When P1>P≥the second preset pressure P2, a second indication signal is generated. The second indication signal is used to indicate that the landing sinking speed is less than the preset speed and the landing gear needs to be inspected after landing;

[0057] When P<P2, a third indication signal is generated. The third indication signal is used to indicate that external facilities are needed to complete the landing and the landing gear needs to be inspected after landing;

[0058] Wherein, the first preset pressure P1 is greater than the second preset pressure P2.

[0059] Exemplarily, the present invention provides a helicopter landing gear retraction system. The system includes: a buffer 9, a retractable cylinder 3, a pressure sensor 13, a first pilot-operated check valve 15, a second pilot-operated check valve 14, and a third pilot-operated check valve 7. The composition of the retraction system is as Figure 1 shown.

[0060] Exemplarily, the buffer 9 can adopt the buffer in the patent ZL201711256532.1.

[0061] The principle of the landing gear retraction is as Figure 1 shown:

[0062] After receiving the retraction command, the hydraulic system supplies pressure to the retraction pressure supply port 6; the hydraulic pressure passes through the third pilot-operated check valve 7 and supplies pressure to the shock absorber 9 and the right chamber 11, pushing the piston rod 8 of the shock absorber 9 upward for retraction; at the same time, the hydraulic pressure connects the first pilot-operated check valve 15 and the second pilot-operated check valve 14 through the pilot control end; the oil in the left chamber 12 of the shock absorber 9 that is compressed flows through the first pilot-operated check valve 15 and the second pilot-operated check valve 14 into the upper chamber 1 of the retraction and extension cylinder 3; and pushes the piston 2 of the retraction and extension cylinder 3 downward; the oil in the lower chamber 4 of the retraction and extension cylinder 3 flows back to the hydraulic system through the lowering pressure supply port 5.

[0063] After receiving the lowering command, the hydraulic system supplies pressure to the lowering pressure supply port 5; the hydraulic pressure flows into the lower chamber 4 of the retraction and extension cylinder 3, pushing the piston 2 of the retraction and extension cylinder 3 upward; the oil in the upper chamber 1 of the retraction and extension cylinder 3 that is compressed flows through the first pilot-operated check valve 15 and the second pilot-operated check valve 14 into the left chamber 12 of the shock absorber 9; at the same time, the hydraulic pressure connects the third pilot-operated check valve 7 through the pilot control end; the oil in the left chamber 12 of the shock absorber 9 that is compressed pushes the piston rod 8 of the shock absorber 9 downward; the oil in the right chamber 11 of the shock absorber 9 flows back to the hydraulic system through the third pilot-operated check valve 7 and the retraction pressure supply port 6.

[0064] The shock absorber 9 adopts the shock absorber in Patent ZL201711256532.1: It includes a low-pressure gas chamber, a high-pressure gas chamber and an oil chamber, which can achieve two-stage energy absorption and can meet various landing speed requirements; at the same time, the shock absorber 9 includes retraction and lowering oil inlet ports and a retraction and extension piston 10. When external pressure is applied, the piston rod 8 of the shock absorber 9 can be retracted or lowered, thereby realizing the retraction or lowering of the landing gear.

[0065] The upper chamber 1 of the retraction and extension cylinder 3 is used to store the oil transferred when the shock absorber 9 is retracted, and the lower chamber 4 is used to receive the oil from the hydraulic system. The piston 2 is used to isolate the upper chamber 1 and the lower chamber 4, which can prevent the oil inside the shock absorber 9 from mixing with the oil of the hydraulic system and make the two not affect each other. At the same time, the cross-sectional area of the lower chamber 4 is smaller than that of the upper chamber 1. Under the same actuation stroke, the hydraulic system can lower the landing gear with less oil. When there is oil leakage in the hydraulic system, the less oil is needed to lower the landing gear, the higher the safety of the landing gear lowering function.

[0066] After the landing gear is retracted, an upper lock is required to lock the landing gear in the retracted position; after the landing gear is lowered, a lower lock is required to lock the landing gear in the lowered position. From the perspective of functional safety, higher reliability requirements are imposed on the lower lock. Both the upper and lower locks adopt hydraulic locks, which are different from the commonly used mechanical locks. The upper lock uses the third hydraulic check valve 7, and the lower lock uses the first hydraulic check valve 15 and the second hydraulic check valve 14 connected in series to improve reliability. When the landing gear is in the retracted position, due to the cut-off function of the third hydraulic check valve 7, the oil in the right chamber 11 of the buffer 9 cannot flow back to the hydraulic system. Therefore, the landing gear piston rod 8 is held in the retracted position under the action of the oil pressure in the right chamber 11 of the buffer 9. When the landing gear is in the lowered position, due to the cut-off function of the first hydraulic check valve 15 and the second hydraulic check valve 14, the oil in the left chamber 12 of the buffer 9 cannot flow back to the hydraulic system, and thus a closed oil chamber is formed in the left chamber 12. Under the action of the pressure in the left chamber 12 of the buffer 9, the landing gear piston rod 8 is held in the lowered position.

[0067] When the landing gear is retracted, part of the oil in the left chamber 12 of the buffer 9 is transferred to the upper chamber 1 of the retraction and extension cylinder 3, and when it is lowered, this part of the oil is transferred back from the upper chamber 1 of the retraction and extension cylinder 3 to the left chamber 12 of the buffer 9. The oil circuit between the left chamber 12 of the buffer 9 and the upper chamber 1 of the retraction and extension cylinder 3 is complex and there are many leakage points, which may cause the oil transferred back to the left chamber 12 of the buffer 9 to decrease when it is lowered. In addition, if the piston 2 of the retraction and extension cylinder 3 gets stuck, it will also cause the oil transferred back to the left chamber 12 of the buffer 9 to become less. This situation will lead to a decrease in the internal cavity pressure of the landing gear and a weakening of the landing gear's ability to absorb landing energy, and in severe cases, it will be unable to support the helicopter's landing. In view of this characteristic, the present invention adds a pressure sensor 13 in the oil circuit to monitor the oil pressure in the left chamber 12 of the buffer 9, as shown in Figure 1 . According to the monitored pressure value, the state of the landing gear is divided into three types, and three different indication signals are generated.

[0068] When P ≥ the first preset pressure P1, a first indication signal is generated; the first indication signal is used to indicate that a normal landing can be made and the landing gear does not need to be inspected after landing;

[0069] When P1 > P ≥ the second preset pressure P2, a second indication signal is generated, and the second indication signal is used to indicate that the landing sinking speed needs to be less than the preset speed and the landing gear needs to be inspected after landing;

[0070] When P < P2, a third indication signal is generated, and the third indication signal is used to indicate that landing needs to be completed with the help of external facilities and the landing gear needs to be inspected after landing.

[0071] As described above, the above are only further embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the scope disclosed by the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, all belong to the protection scope of the present invention.

Claims

1. A helicopter landing gear retraction and extension system, characterized in that, Comprising: a buffer (9) and a retracting and extending oil cylinder (3); wherein, a retracting and extending piston (10) and a piston rod (8) are arranged inside the buffer (9), the retracting and extending piston (10) divides the inside of the buffer (9) into a left chamber (12) and a right chamber (11), and the piston rod (8) is connected to a wheel or a rocker arm; the right chamber (11) is used for receiving the oil fluid of the hydraulic system, and under the drive of the oil fluid of the hydraulic system, the retracting and extending piston (10) moves to drive the piston rod (8) to move; a piston (2) is arranged inside the retracting and extending oil cylinder (3) to form an upper chamber (1) and a lower chamber (4), the upper chamber (1) is communicated with the left chamber (12) of the buffer (9) and is used for storing the oil fluid transferred when the buffer (9) is retracted, and the lower chamber (4) is used for receiving the oil fluid of the hydraulic system; the cross-sectional area of the lower chamber (4) is smaller than that of the upper chamber (1).

2. The helicopter landing gear retraction system according to claim 1, wherein, The cross-sectional area of the lower chamber (4) is half of the cross-sectional area of the upper chamber (1).

3. The helicopter landing gear retraction system according to claim 1, wherein Further comprising: a first hydraulic control check valve (15), a second hydraulic control check valve (14) and a third hydraulic control check valve (7); the control ends of the first hydraulic control check valve (15), the second hydraulic control check valve (14) and the on-off end of the third hydraulic control check valve (7) are connected to the retracting pressure supply port (6) of the hydraulic system; the control end of the third hydraulic control check valve (7) and the lower chamber (4) of the retracting and extending oil cylinder (3) are connected to the extending pressure supply port (5) of the hydraulic system; the on-off end of the first hydraulic control check valve (15) is connected to the upper chamber (1) of the retracting and extending oil cylinder (3), the cut-off end of the first hydraulic control check valve (15) is connected to the on-off end of the second hydraulic control check valve (14), and the cut-off end of the second hydraulic control check valve (14) is connected to the left chamber (12) of the buffer (9); the cut-off end of the third hydraulic control check valve (7) is connected to the right chamber (11) of the buffer (9).

4. The helicopter landing gear retracting and extending system according to claim 3, wherein after receiving a retracting instruction, the hydraulic system supplies pressure to the retracting pressure supply port (6); the hydraulic pressure passes through the third hydraulic control check valve (7) to supply pressure to the buffer (9) and the right chamber (11), and pushes the piston rod (8) of the buffer (9) to retract upwards; meanwhile, the hydraulic pressure turns on the first hydraulic control check valve (15) and the second hydraulic control check valve (14) through the control end; the oil fluid compressed in the left chamber (12) of the buffer (9) flows into the upper chamber (1) of the retracting and extending oil cylinder (3) through the first hydraulic control check valve (15) and the second hydraulic control check valve (14); and pushes the piston (2) of the retracting and extending oil cylinder (3) to move downwards; the oil fluid in the lower chamber (4) of the retracting and extending oil cylinder (3) flows back to the hydraulic system through the extending pressure supply port (5); After receiving the lowering instruction, the hydraulic system supplies pressure to the lowering pressure supply port (5); the hydraulic fluid flows into the lower chamber (4) of the retractable cylinder (3), pushing the piston (2) of the retractable cylinder (3) to move upward; the compressed hydraulic fluid in the upper chamber (1) of the retractable cylinder (3) flows into the left chamber (12) of the buffer (9) through the first pilot-operated check valve (15) and the second pilot-operated check valve (14); meanwhile, the hydraulic fluid controls the third pilot-operated check valve (7) through the control end; the compressed hydraulic fluid in the left chamber (12) of the buffer (9) pushes the piston rod (8) of the buffer (9) to move downward; the hydraulic fluid in the right chamber (11) of the buffer (9) flows back to the hydraulic system through the third pilot-operated check valve (7) and the retraction pressure supply port (6).

5. The helicopter landing gear retraction system according to claim 1, wherein, It further includes: a pressure sensor (13); The pressure sensor (13) is used to monitor the hydraulic pressure P of the hydraulic fluid in the left chamber (12) of the buffer (9).

6. The helicopter landing gear retraction system according to claim 5, characterized in that, When P≥the first preset pressure P1, a first indication signal is generated; the first indication signal is used to indicate that a normal landing can be made and the landing gear does not need to be inspected after landing; When P1>P≥the second preset pressure P2, a second indication signal is generated, and the second indication signal is used to indicate that the landing sinking speed needs to be less than the preset speed, and the landing gear is inspected after landing; When P<P2, a third indication signal is generated, and the third indication signal is used to indicate that external facilities are needed to complete the landing, and the landing gear is inspected after landing; Wherein, the first preset pressure P1 is greater than the second preset pressure P2.

7. The helicopter landing gear retraction system according to claim 6, characterized in that, The first preset pressure P1 is 30 bar; The second preset pressure P2 is 20 bar.

8. The helicopter landing gear retraction system according to claim 6, characterized in that, The preset speed is 1.6 m / s.

9. A helicopter landing gear, characterized in that, The helicopter landing gear retraction system as described in any one of claims 1-8 is adopted.

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