A dual coaxial dual-rotor aircraft transmission system and rotorcraft with tiltable tail rotor

Abstract

The application relates to a transmission system of a double coaxial double-rotor machine with tiltable tail rotor and a rotor aircraft, which comprises a parallel reduction unit, a reversing transmission unit, a tail reduction and tilting output unit and double-rotor output units symmetrically connected on the two sides of the reversing transmission unit, the reversing transmission unit is symmetrically connected on the two sides of the parallel reduction unit, and the tail reduction and tilting output unit is installed on the opposite side of the double-rotor output unit; the transmission system adopts two engine outputs, the power is transmitted to the left rotor shaft, the right rotor shaft and the tail rotor through the two-stage cylindrical gear reduction of the parallel reduction unit and the reversing transmission unit and the tail reduction and tilting output unit respectively; the design of the two groups of symmetrically distributed coaxial double rotors on the two sides of the fuselage and the tiltable tail rotor can improve the helicopter power utilization efficiency, hovering efficiency, acceleration characteristics, manipulation diversity and stability, and is beneficial to reducing the weight of the system.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology and relates to a transmission system for a dual coaxial rotorcraft with a tilting tail rotor and a rotorcraft. Background Technology

[0002] Based on the different methods of rotor torque balancing, helicopters are generally classified into single-rotor with tail rotor, coaxial twin-rotor, tandem twin-rotor, and transverse twin-rotor types. Coaxial helicopters use two sets of rotors that rotate in opposite directions along the same axis to balance rotor torque, eliminating the power loss associated with a tail rotor for torque balancing. They are characterized by high hovering efficiency, small overall size, and strong acceleration characteristics. However, currently, coaxial helicopters developed domestically and internationally only contain one set of coaxial twin rotors and rely on a vertical tail to improve directional control efficiency. This is only effective at higher flight speeds and suffers from poor handling performance, poor stability, and limited tolerance for changes in the center of gravity.

[0003] The use of two symmetrically distributed coaxial rotors on both sides of the fuselage, along with two tilting tail rotors, improves the efficiency and maneuverability of the entire power system. This allows the helicopter to hover and take off and land more efficiently, adapt to greater changes in the center of gravity, and possess stronger acceleration characteristics. The transmission system is one of the key moving components of a coaxial twin-rotor aircraft. Existing transmission systems cannot adequately transmit engine power to the two coaxial rotors and tilting tail rotors. Therefore, it is necessary to propose a novel transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor to address the problems existing in current designs. Summary of the Invention

[0004] In view of this, in order to solve the problems of poor handling performance, poor stability and small allowable center of gravity change of current coaxial twin rotor aircraft, resulting in low efficiency and low maneuverability of the power system, the present invention provides a lightweight, compact, and highly efficient twin coaxial twin rotor transmission system and rotorcraft with a tilting tail rotor.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A transmission system for a twin-coaxial twin-rotor aircraft with a tiltable tail rotor includes a parallel reduction unit, a reversing transmission unit, a tail reduction tilt output unit, and twin-rotor output units symmetrically connected on both sides of the reversing transmission unit. The reversing transmission units are symmetrically connected on both sides of the parallel reduction unit, and the tail reduction tilt output units are installed on the opposite side of the twin-rotor output units.

[0007] The parallel reduction unit includes a first gear shaft, a third cylindrical gear fixedly connected to one end of the first gear shaft, a second cylindrical gear and a first cylindrical gear that are symmetrically meshed on both sides of the third cylindrical gear in sequence, and the gear shaft where the first cylindrical gear is located is connected to the power source.

[0008] The reversing transmission unit includes two first reversing transmission shafts and two second reversing drive shafts that are reversing transmission connected to the first gear shaft. The second reversing drive shafts are axially connected to the outside of the corresponding first reversing transmission shafts.

[0009] Each of the dual rotor output units includes a second gear shaft that is reversing and driving the second reversing shaft, a third gear shaft that is reversing and driving the second gear shaft, and an upper rotor shaft and a lower rotor shaft that are driving each other. The upper rotor shaft and the lower rotor shaft are respectively drivingly connected to the second gear shaft, and the upper rotor shaft is drivingly connected above the lower rotor shaft.

[0010] The tail reduction tilt output unit includes a first tail drive shaft and a second tail drive shaft that are sequentially connected to the first gear shaft without reversing direction. The second tail drive shaft is connected to the two tail reduction drive shafts in reverse direction, and the outer side of the tail reduction drive shaft is connected to the tail reduction output shaft in reverse direction.

[0011] Furthermore, the third cylindrical gear is integrally formed and fixedly installed on the first gear shaft near the tail reducer tilt output unit. The second cylindrical gear is symmetrically arranged on both sides of the third cylindrical gear through its own gear shaft and meshes with the third cylindrical gear. The first cylindrical gear is symmetrically arranged on both sides of the second cylindrical gear through its own gear shaft and meshes with the second cylindrical gear. The engine is connected to the power input shaft where the second cylindrical gear is located.

[0012] Furthermore, an overrunning clutch is installed on the power input shaft. The output power of the two engines, which are respectively connected to the power input shaft, is collected by the third cylindrical gear of the parallel reduction unit and sent to the first gear shaft. The power is then transmitted to the dual rotor output unit and the tail reduction tilt output unit through the first gear shaft.

[0013] Furthermore, a first bevel gear is integrally formed and fixedly installed on one end of the first gear shaft near the reversing transmission unit, and a first reversing bevel gear that meshes with the first bevel gear is integrally formed and fixedly installed on one of the first reversing transmission shafts at the docking point of the first reversing transmission shaft.

[0014] Furthermore, a second bevel gear is integrally formed and fixedly installed on one end of the second reversing shaft near the dual rotor output unit. A second reversing bevel gear and a third reversing bevel gear are integrally formed and fixedly installed on the second gear shaft in sequence. Both the second and third reversing bevel gears mesh with the second bevel gear. The second reversing bevel gear is connected to the fifth cylindrical gear through a gear shaft, and the third reversing bevel gear is connected to the sixth cylindrical gear through a gear shaft. The upper rotor shaft is driven and connected above the lower rotor shaft. A seventh cylindrical gear that meshes with the fifth cylindrical gear is installed on the upper rotor shaft, and an eighth cylindrical gear that meshes with the sixth cylindrical gear is installed on the lower rotor shaft.

[0015] Furthermore, an accessory bevel gear is integrally formed and fixedly installed on the third gear shaft, and the accessory bevel gear meshes with the second reversing bevel gear.

[0016] Furthermore, a fourth cylindrical gear that meshes with the third cylindrical gear is integrally formed and fixedly installed on the end of the first tail drive shaft near the parallel reduction unit. The end of the second tail drive shaft away from the first tail drive shaft is sequentially connected to the sun gear input shaft, the planetary gear set, and the planet carrier. A first-stage tail reduction bevel gear is integrally formed and fixedly installed on the end of the planet carrier. On one of the tail reduction drive shafts at the opposite end, a first-stage tail reduction reversing bevel gear that meshes with the first-stage tail reduction bevel gear is integrally formed and fixedly installed. A second-stage tail reduction bevel gear is integrally formed and fixedly installed on the end of the tail reduction drive shaft. A second-stage tail reduction reversing bevel gear that meshes with the second-stage tail reduction bevel gear is integrally formed and fixedly installed on the end of the tail reduction output shaft.

[0017] Furthermore, the first tail drive shaft is connected to the gear shaft of the fourth cylindrical gear via a spline, and the second tail drive shaft is connected to the first tail drive shaft via a spline and a diaphragm coupling. A deep groove ball bearing is installed on the first tail drive shaft to provide support. The gear shaft where the tail reduction first-stage bevel gear is located is connected to the planet carrier via a spline. A deep groove ball bearing is installed on the planet carrier to provide support. A four-point contact ball bearing and a cylindrical roller bearing are installed on the gear shaft where the tail reduction first-stage bevel gear is located to provide support.

[0018] Furthermore, tapered roller bearings are installed on the tail reducer drive shaft at the tail reducer secondary bevel gear and tail reducer primary reversing bevel gear to provide support, and tapered roller bearings are installed on the tail reducer output shaft to provide support.

[0019] A rotorcraft includes a fuselage and the aforementioned dual coaxial rotor transmission system with a tilting tail rotor, wherein the aforementioned dual coaxial rotor transmission system with a tilting tail rotor is disposed within the fuselage.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. The dual coaxial rotor transmission system with tiltable tail rotor disclosed in this invention employs two engine outputs. After being reduced in speed by two stages of cylindrical gears in a parallel reduction unit, the power is transmitted to the left rotor shaft, right rotor shaft, and tail rotor respectively through a reversing transmission unit and a tail reduction tilting output unit. The dual rotor output unit achieves coaxial reversal of the upper and lower rotors through inner and outer shafts. The two tail rotors rotate in opposite directions to balance the anti-torque. At the same time, the tail rotor can tilt around the tail reduction reversing bevel gear. This design, which uses two sets of coaxial dual rotors symmetrically distributed on both sides of the fuselage with tiltable tail rotors, can improve the helicopter's power utilization efficiency, hovering efficiency, acceleration characteristics, control mode diversity and stability, while also helping to reduce the weight of the system.

[0022] 2. The dual coaxial rotorcraft transmission system with tilting tail rotor disclosed in this invention adopts two sets of coaxial counter-rotating rotors. At the same time, the first reversing bevel gear of the reversing transmission unit and the tail reduction first-stage bevel gear of the tail reduction tilting output unit both adopt a pair of bevel gears for reversing. Compared with the traditional coaxial rotorcraft transmission system, this structure is more compact, has higher power utilization efficiency, can greatly improve hovering efficiency, reduce system weight, and reduce structural size.

[0023] 3. The dual coaxial rotor transmission system with tiltable tail rotor disclosed in this invention can not only realize the movement of a conventional helicopter in all directions through the rotor, but also realize directional control and acceleration and deceleration by adjusting the tail rotor speed, enabling the helicopter to achieve vertical take-off and landing, climb and turn more quickly, and improving control stability.

[0024] 4. The dual coaxial rotor transmission system with tiltable tail rotor disclosed in this invention can provide lift when the helicopter is hovering and climbing, and provide thrust when flying forward and changing direction by tilting the tail rotor, which greatly improves the acceleration characteristics and high-speed forward flight capability of the whole aircraft.

[0025] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a schematic diagram of the transmission system of the twin coaxial rotorcraft with tiltable tail rotor of the present invention;

[0028] Figure 2 This is a schematic diagram of the transmission principle of the twin coaxial rotorcraft transmission system with tiltable tail rotor of the present invention.

[0029] Reference numerals: Power input shaft 1, Overrunning clutch 2, First cylindrical gear 11, Second cylindrical gear 9, Fourth cylindrical gear 4, Accessory cylindrical gears 6, 8, First bevel gear 14, First reversing bevel gear 16, First gear shaft 17, Third cylindrical gear 20, First reversing drive shaft 21, Second reversing drive shaft 23, Fifth cylindrical gear 25, Second reversing bevel gear 27, Second bevel gear 28, Third reversing bevel gear 29, Sixth cylindrical gear 30, Upper rotor shaft 32, Lower rotor shaft 34, Seventh cylindrical gear 37, Accessory bevel gear 38, Eighth cylindrical gear 42, Sun gear input shaft 45, Traveling gear... Planetary gear set 46, planetary carrier 48, tail reducer output shaft 50, tail reducer second-stage reversing bevel gear 53, tail reducer second-stage bevel gear 54, tail reducer drive shaft 56, tail reducer first-stage reversing bevel gear 58, tail reducer first-stage bevel gear 59, first tail drive shaft 61, second tail drive shaft 64, diaphragm couplings 19, 43, 62, deep groove ball bearings 3, 5, 7, 10, 18, 22, 39, 41, 44, 47, 63, cylindrical roller bearings 13, 15, 36, 40, 60, four-point contact ball bearings 12, 24, 26, 31, 33, 35, 49, tapered roller bearings 51, 52, 55, 57. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0032] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0033] like Figures 1-2 The transmission system of the twin coaxial rotorcraft with a tilting tail rotor shown includes a parallel reduction unit, a reversing transmission unit, a tail reduction tilting output unit, and twin rotor output units symmetrically connected on both sides of the reversing transmission unit. The reversing transmission unit is symmetrically connected on both sides of the parallel reduction unit, and the tail reduction tilting output unit is installed on the opposite side of the twin rotor output unit. The parallel reduction unit is connected to the power input shaft 1.

[0034] The parallel reduction unit includes a first gear shaft 17, a third cylindrical gear 20 fixedly connected to one end of the first gear shaft 17, a second cylindrical gear 9 symmetrically meshed on both sides of the third cylindrical gear 20, and a first cylindrical gear 11 symmetrically meshed on both sides of the second cylindrical gear 9. The gear shaft where the first cylindrical gear 11 is located is the power input shaft 1. The first cylindrical gear 11 is fixedly connected to the power input shaft 1. An overrunning clutch is installed on the power input shaft 1. The output power of the two engines respectively connected to the power input shaft 1 is collected by the third cylindrical gear 20 of the parallel reduction unit and sent to the first gear shaft 17, and then transmitted to the dual rotor output unit and the tail reduction tilt output unit respectively through the first gear shaft 17.

[0035] Specifically, the third cylindrical gear 20 is integrally formed and fixedly mounted on the first gear shaft 17 near the tail reducer tilt output unit. The second cylindrical gear 9 is symmetrically arranged on both sides of the third cylindrical gear 20 through its own gear shaft and meshes with the third cylindrical gear 20. The first cylindrical gear 11 is symmetrically arranged on both sides of the second cylindrical gear 9 through its own gear shaft and meshes with the second cylindrical gear 9. The engine is connected to the power input shaft 1 where the second cylindrical gear 9 is located. All gears are integrally formed with the gear shaft, and deep groove ball bearings 3, 5, 7, and 10 are installed on the corresponding gear shaft to provide support.

[0036] The reversing transmission unit includes two first reversing drive shafts 21 and two second reversing drive shafts 23 that are reversingly connected to the first gear shaft 17. Deep groove ball bearings 22 are installed at the connection points of the first and second reversing drive shafts 21 and 23 to provide support. The second reversing drive shafts 23 are axially connected to the outer side of the corresponding first reversing drive shaft 21. Specifically, a first bevel gear 14 is integrally formed and fixedly installed on one end of the first gear shaft 17 near the reversing transmission unit. A first reversing bevel gear 16, meshing with the first bevel gear 14, is integrally formed and fixedly installed on one of the first reversing drive shafts 21 at the mating point. Deep groove ball bearings 18 and diaphragm couplings 19 are installed on the first reversing drive shaft 21 where the first reversing bevel gear 16 is located to provide support. Four-point contact ball bearings 12 and cylindrical roller bearings 13 are installed on the first gear shaft 17 where the first bevel gear 14 is located to provide support. Cylindrical roller bearings 15 are installed on the drive shaft where the first reversing bevel gear 16 is located to provide support.

[0037] Each of the dual rotor output units includes a second gear shaft that is reversing and driving the second reversing shaft 23, a third gear shaft that is reversing and driving the second gear shaft, and an upper rotor shaft 32 and a lower rotor shaft 34 that are driving each other. The upper rotor shaft 32 and the lower rotor shaft 34 are respectively drivingly connected to the second gear shaft, and the upper rotor shaft 32 is drivingly connected above the lower rotor shaft 34.

[0038] Specifically, a second bevel gear 28 is integrally formed and fixedly mounted on the second reversing shaft 23 near the end of the dual-rotor output unit. A four-point contact ball bearing 26 is installed on the second reversing shaft 23 where the second bevel gear 28 is located to provide support. A second reversing bevel gear 27 and a third reversing bevel gear 29 are integrally formed and fixedly mounted on the second gear shaft in sequence. Both the second reversing bevel gear 27 and the third reversing bevel gear 29 mesh with the second bevel gear 28. The second reversing bevel gear 27 is connected to the fifth cylindrical gear 25 through a gear shaft, and the third reversing bevel gear 29 is connected to the sixth cylindrical gear 30 through a gear shaft. Four-point contact ball bearings 24 and 31 are installed on the second gear shaft to provide support. The upper rotor shaft 32 is driven and connected above the lower rotor shaft 34. A seventh cylindrical gear 37 that meshes with the fifth cylindrical gear 25 is installed on the upper rotor shaft 32, and an eighth cylindrical gear 42 that meshes with the sixth cylindrical gear 30 is installed on the lower rotor shaft 34.

[0039] An accessory bevel gear 38 is integrally formed and fixedly mounted on the third gear shaft. The accessory bevel gear 38 meshes with the second reversing bevel gear 27. Deep groove ball bearings 39 and 41 are installed on the third gear shaft where the accessory bevel gear 38 is located to provide support. A four-point contact ball bearing 33 and a cylindrical roller bearing 40 are installed on the upper rotor shaft 32 to provide support, and a four-point contact ball bearing 35 and a cylindrical roller bearing 36 are installed on the lower rotor shaft 34 to provide support. The coaxial reverse rotation of the coaxial dual rotors on the left and right sides of the dual rotor output unit is achieved to counteract the rotor reverse torque.

[0040] The tail reduction tilt output unit includes a first tail drive shaft 61 and a second tail drive shaft 64 that are sequentially connected to the first gear shaft 17 without reversing direction. The second tail drive shaft 64 is connected to two tail reduction drive shafts 56 in reverse direction, and the outer side of the tail reduction drive shaft 56 is connected to the tail reduction output shaft 50 in reverse direction.

[0041] Specifically, a fourth cylindrical gear 4, which meshes with the third cylindrical gear 20, is integrally formed and fixedly installed on the end of the first tail drive shaft 61 near the parallel reduction unit. Accessory cylindrical gears 6 and 8 are connected to the end of the first tail drive shaft 61 on one side of the fourth cylindrical gear 4 via gear shaft transmission. The gear shafts of the first tail drive shaft 61 and the fourth cylindrical gear 4 are connected by a spline. The second tail drive shaft 64 is connected to the first tail drive shaft 61 via a spline and a diaphragm coupling 62. A deep groove ball bearing 63 is installed on the first tail drive shaft 61 for support. The end of the second tail drive shaft 64 away from the first tail drive shaft 61 is sequentially connected to the sun gear input shaft 45, the planetary gear set 46, and the parallel gear set 47. The planetary carrier 48 has a diaphragm coupling 43 and a deep groove ball bearing 44 mounted on the sun gear input shaft 45 for support. A tail reduction first-stage bevel gear 59 is integrally formed and fixedly mounted at the end of the planetary carrier 48. One of the tail reduction drive shafts 56 at the opposite end has a tail reduction first-stage reversing bevel gear 58 integrally formed and fixedly mounted on it, which meshes with the tail reduction first-stage bevel gear 59. The gear shaft where the tail reduction first-stage bevel gear 59 is located is connected to the planetary carrier 48 via a spline. A deep groove ball bearing 47 is mounted on the planetary carrier 48 for support. A four-point contact ball bearing 49 and a cylindrical roller bearing 60 are mounted on the gear shaft where the tail reduction first-stage bevel gear 59 is located for support.

[0042] The tail rotor drive shaft 56 has a tail rotor secondary bevel gear 54 integrally formed and fixedly mounted at its end. The tail rotor output shaft 50 has a tail rotor secondary reversing bevel gear 53 integrally formed and fixedly mounted at its end, meshing with the tail rotor secondary bevel gear 54. The tail rotor secondary reversing bevel gear 53 is connected to the tail rotor primary reversing bevel gear 58 via the tail rotor drive shaft 56. Tapered roller bearings 55 and 57 are installed on the tail rotor drive shaft 56 at the tail rotor secondary bevel gear 54 and the tail rotor primary reversing bevel gear 58 to provide support. Tapered roller bearings 51 and 52 are installed on the tail rotor output shaft 50 to provide support. The tail rotor output shaft 50 can rotate relative to the tail rotor secondary bevel gear 54. The two symmetrical tail rotor output shafts 50 rotate in opposite directions to balance the tail rotor counter-torque. When the helicopter takes off and lands vertically and flies forward at low speed, the tail rotor output shaft 50 is in normal working condition. When the helicopter flies forward at high speed, the tail rotor output shaft 50 tilts to provide thrust for the helicopter's forward movement.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor, characterized in that, It includes a parallel deceleration unit, a reversing transmission unit, a tail deceleration tilt output unit, and a dual rotor output unit symmetrically connected on both sides of the reversing transmission unit. The reversing transmission unit is symmetrically connected on both sides of the parallel deceleration unit, and the tail deceleration tilt output unit is installed on the opposite side of the dual rotor output unit. The parallel deceleration unit includes a first gear shaft (17), a third cylindrical gear (20) fixedly connected to one end of the first gear shaft (17), a second cylindrical gear (9) and a first cylindrical gear (11) symmetrically meshed on both sides of the third cylindrical gear (20), and the gear shaft where the first cylindrical gear (11) is located is connected to the power source. The reversing transmission unit includes two first reversing transmission shafts (21) and two second reversing drive shafts (23) that are reversing transmission connected to the first gear shaft (17). The second reversing drive shafts (23) are axially connected to the outside of the corresponding first reversing transmission shafts (21). The dual rotor output unit includes a second gear shaft that is reversing and driving the second reversing shaft (23), a third gear shaft that is reversing and driving the second gear shaft, and an upper rotor shaft (32) and a lower rotor shaft (34) that are mutually driving and driving. The upper rotor shaft (32) and the lower rotor shaft (34) are respectively driving and drivingly connected to the second gear shaft, and the upper rotor shaft (32) is driving and drivingly connected above the lower rotor shaft (34). The tail reduction tilt output unit includes a first tail drive shaft (61) and a second tail drive shaft (64) that are sequentially connected to the first gear shaft (17) without reversing direction. The second tail drive shaft (64) is connected to two tail reduction drive shafts (56) in reverse direction. The outer side of the tail reduction drive shaft (56) is connected to the tail reduction output shaft (50) in reverse direction. The first tail drive shaft (61) is integrally formed and fixedly installed with a fourth cylindrical gear (4) that meshes with the third cylindrical gear (20) at one end near the parallel reduction unit. The second tail drive shaft (64) is connected in sequence to the sun gear input shaft (45), the planetary gear set (46) and the planet carrier (48) at the other end away from the first tail drive shaft (61). The end of the planet carrier (48) is integrally formed and fixedly installed with a tail reduction first-stage bevel gear (59). On one of the tail reduction drive shafts (56) at the opposite end, a tail reduction first-stage reversing bevel gear (58) that meshes with the tail reduction first-stage bevel gear (59) is integrally formed and fixedly installed. The end of the tail reduction drive shaft (56) is integrally formed and fixedly installed with a tail reduction second-stage bevel gear (54). The end of the tail reduction output shaft (50) is integrally formed and fixedly installed with a tail reduction second-stage reversing bevel gear (53) that meshes with the tail reduction second-stage bevel gear (54).

2. The transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor as described in claim 1, characterized in that, The third cylindrical gear (20) is integrally formed and fixedly installed on the first gear shaft (17) near the tail reduction tilt output unit. The second cylindrical gear (9) is symmetrically arranged on both sides of the third cylindrical gear (20) through the gear shaft and meshes with the third cylindrical gear (20). The first cylindrical gear (11) is symmetrically arranged on both sides of the second cylindrical gear (9) through the gear shaft and meshes with the second cylindrical gear (9). The engine is connected to the power input shaft (1) where the second cylindrical gear (9) is located.

3. The twin-coaxial twin-rotor transmission system with a tilting tail rotor as described in claim 2, characterized in that, An overrunning clutch is installed on the power input shaft (1). The output power of the two engines connected to the power input shaft (1) is collected by the third cylindrical gear (20) of the parallel reduction unit to the first gear shaft (17), and then transmitted to the dual rotor output unit and the tail reduction tilt output unit respectively through the first gear shaft (17).

4. The transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor as described in claim 1, characterized in that, The first gear shaft (17) is integrally formed and fixedly installed with a first bevel gear (14) near the reversing transmission unit. The first reversing transmission shaft (21) at the docking point of the first reversing transmission shaft (21) is integrally formed and fixedly installed with a first reversing bevel gear (16) that meshes with the first bevel gear (14).

5. The transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor as described in claim 1, characterized in that, The second reversing shaft (23) is integrally formed and fixedly installed with a second bevel gear (28) near the end of the dual rotor output unit. The second reversing bevel gear (27) and the third reversing bevel gear (29) are integrally formed and fixedly installed on the second gear shaft in sequence. The second reversing bevel gear (27) and the third reversing bevel gear (29) are both meshed with the second bevel gear (28). The second reversing bevel gear (27) is connected to the fifth cylindrical gear (25) through the gear shaft. The third reversing bevel gear (29) is connected to the sixth cylindrical gear (30) through the gear shaft. The upper rotor shaft (32) is driven and connected above the lower rotor shaft (34). The upper rotor shaft (32) is equipped with a seventh cylindrical gear (37) that meshes with the fifth cylindrical gear (25). The lower rotor shaft (34) is equipped with an eighth cylindrical gear (42) that meshes with the sixth cylindrical gear (30).

6. The transmission system for a twin-coaxial twin-rotor aircraft with a tilting tail rotor as described in claim 5, characterized in that, An accessory bevel gear (38) is integrally formed and fixedly installed on the third gear shaft, and the accessory bevel gear (38) meshes with the second reversing bevel gear (27).

7. A rotary-wing aircraft, characterized in that, The invention includes a fuselage and a twin-coaxial rotorcraft transmission system with a tilting tail rotor as described in any one of claims 1 to 6, wherein the fuselage houses the twin-coaxial rotorcraft transmission system with a tilting tail rotor.

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