Face gear transmission double-rotor tandem helicopter power transmission system and rotorcraft

Abstract

The invention discloses a face gear transmission double-rotor tandem helicopter power transmission system and a rotorcraft, and the system comprises two groups of head speed reducers which are symmetrically arranged and are in transmission connection with each other through parallel operation speed reducers; the two groups of head speed reducers are respectively provided with one driving device, and the driving devices are axially vertical to the head speed reducers; the synchronizing shaft is arranged in the parallel operation speed reducer and is axially parallel to the two groups of head speed reducers and the driving device, one end of the synchronizing shaft is in transmission connection with a front speed reducer, the other end of the synchronizing shaft is connected with a rear speed reducer, and the front speed reducer is axially parallel to the rear speed reducer. The high-speed low-torque power of the driving device is changed into the low-speed high-torque power of the rotor wings through the three-stage face gear pair, the transmission stage number is reduced, the number of parts of a transmission system is effectively reduced, and the reliability of the transmission system is improved.

Description

Technical Field

[0001] The invention belongs to the field of aviation technology, and in particular relates to a face gear transmission twin-rotor tandem helicopter power transmission system and a rotorcraft. Background Art

[0002] In the field of helicopter technology, twin-rotor tandem helicopters play an important role in many specific scenarios due to their unique advantages. Compared with single-rotor helicopters, the front and rear rotors of twin-rotor tandem helicopters work together to generate lift and can provide greater total lift. This feature enables it to perform well in tasks such as transporting heavy cargo, equipment and personnel, and has significant advantages in key areas such as military transportation and engineering lifting.

[0003] At the same time, the twin-rotor tandem helicopter uses a twin-rotor system with symmetrical layout and independent pitch control. This design can effectively offset torque, eliminating the need for a tail rotor. When hovering, flying at low speed, and in a complex airflow environment, the helicopter exhibits a more stable attitude control capability, with higher control accuracy and wide environmental applicability.

[0004] However, twin-rotor tandem helicopters also have some disadvantages that cannot be ignored, the most prominent of which is the complex structure, which directly leads to high manufacturing and maintenance costs. In particular, the transmission system structure is extremely complex. Take the Boeing Vertol 107 twin-rotor tandem helicopter in the United States as an example. Its power transmission process is that the two engines input high-speed and low-torque power, and use multi-stage gear transmission to achieve high-torque and low-speed output of the front and rear rotors. Specifically, its transmission system adopts a four-stage gear transmission method of herringbone gear first-stage reduction, cylindrical gear parallel reduction, bevel gear reversing reduction and planetary gear reduction, with a total transmission ratio of up to about 74.

[0005] Such a large total transmission ratio strictly limits the single-stage transmission ratio of the cylindrical gear pair and the bevel gear pair, and it cannot be too large, otherwise it will further threaten the stability and reliability of the entire transmission system. In order to meet the large transmission ratio requirements of the twin-rotor tandem helicopter, the number of transmission stages and mechanical components has to be increased, but this brings new problems, namely, the reliability of the transmission system is reduced and the risk of failure is increased. Therefore, how to optimize the power transmission system of the twin-rotor tandem helicopter, while ensuring the realization of a large transmission ratio, improving the reliability of the transmission system and reducing the risk of failure has become a key issue that needs to be urgently solved in the current field of helicopter technology. Summary of the invention

[0006] The purpose of the present invention is to provide a face gear transmission twin-rotor tandem helicopter power transmission system and a rotorcraft, so as to solve the technical defects of the prior art twin-rotor tandem helicopter transmission system with many transmission stages, many mechanical parts, low reliability and high failure risk.

[0007] To achieve the above object, the present invention is implemented by the following technical solutions: In a first aspect, a power transmission system for a face gear drive tandem rotor helicopter is provided, including: Two sets of head reducers, symmetrically arranged and drivingly connected to each other through a parallel shaft reducer; A driving device, with one driving device provided on each of the two sets of head reducers, and the driving device is axially perpendicular to the head reducer; A synchronizing shaft, arranged in the parallel shaft reducer, axially parallel to the two sets of head reducers and the driving device, with a front reducer drivingly connected to one end thereof, and a rear reducer connected to the other end, and the front reducer and the rear reducer are axially parallel to each other.

[0008] Further, the parallel shaft reducer includes: Two parallel shaft driven face gears, arranged opposite to each other, and both ends between the two parallel shaft driven face gears are connected by cylindrical gears, and the cylindrical gears are meshed with the two sets of head reducers; The synchronizing shaft includes: A front synchronizing shaft and a rear synchronizing shaft, one end of the front synchronizing shaft is connected to the front reducer, and the other end is connected to one of the parallel shaft driven face gears; One end of the rear synchronizing shaft is connected to the rear reducer, and the other end is connected to the other parallel shaft driven face gear.

[0009] Further, the front reducer includes: A front driving cylindrical gear, arranged at the end of the front synchronizing shaft, and a front driven face gear meshed with the bottom thereof, the front driven face gear is arranged outside the front rotor shaft, and the top of the front rotor shaft is connected to a front rotor; The rear reducer includes: A rear driving cylindrical gear, arranged at the end of the rear synchronizing shaft, and a rear driven face gear meshed with the top thereof, the rear driven face gear is arranged outside the rear rotor shaft, and the top of the rear rotor shaft is connected to a rear rotor.

[0010] Further, the two sets of head reducers have the same structure, and the head reducer includes: A head driving cylindrical gear, arranged at the driving end of the driving device, and a head driven face gear meshed with the outside thereof, a main transmission shaft is provided in the head driven face gear, and the end of the main transmission shaft is fixedly connected to the parallel shaft reducer.

[0011] Further, the head driving cylindrical gear and the head driven face gear are axially perpendicular to each other.

[0012] Further, the main transmission shaft and the head driven face gear are axially coincident.

[0013] Further, the driving device is an engine.

[0014] Further, the rear speed reducer is located between the two driving devices.

[0015] Further, the front speed reducer and the rear speed reducer are axially perpendicular to the synchronizing shaft.

[0016] In a second aspect, a gyrocopter is provided, including a gyrocopter body, and the gyrocopter body is equipped with the face gear drive dual-rotor tandem helicopter power transmission system as described above.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Through the three-stage face gear pair, the high-speed and low-torque power of the driving device is transformed into the low-speed and high-torque power of the rotor, reducing the number of transmission stages, effectively reducing the number of parts of the transmission system, and improving the reliability of the transmission system.

[0018] 2. The two parallel-connected driven face gears are arranged oppositely and meshed with two groups of head speed reducers through cylindrical gears, so that the power can be efficiently and evenly distributed from the driving device to the front and rear rotor systems; the meshing transmission of the cylindrical gears can ensure the stability and accuracy of power transmission, and avoid the speed difference between the front and rear rotors caused by uneven power distribution.

[0019] 3. The front driving cylindrical gear is arranged at the end of the front synchronizing shaft and meshed with the bottom of the front driven face gear, which can ensure the efficient and accurate transmission of power from the front synchronizing shaft to the front rotor shaft; similarly, the rear driving cylindrical gear in the rear speed reducer is meshed with the top of the rear driven face gear to realize the reliable transmission of power from the rear synchronizing shaft to the rear rotor shaft; the meshing mode of the cylindrical gear and the face gear has high transmission efficiency and transmission accuracy, reducing the energy loss and error accumulation during power transmission.

[0020] 4. The head driving cylindrical gear is arranged on the driving end of the driving device and meshed with the outside of the head driven face gear, which has high transmission efficiency, can reduce the energy loss between gears, and ensure the efficient transmission of the power generated by the driving device to the subsequent transmission components.

[0021] 5. The design that the head driving cylindrical gear and the head driven face gear are axially perpendicular can efficiently change the direction of the power output by the driving device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 Schematic diagram of the power transmission system of a face gear transmission twin-rotor tandem helicopter provided by the present invention; Figure 2 Stereoscopic diagram of the power transmission system of a face gear transmission twin-rotor tandem helicopter provided by the present invention; Figure 3 Top view of the power transmission system of a face gear transmission twin-rotor tandem helicopter provided by the present invention; Figure 4 Schematic diagram of the structure of the front reducer in the power transmission system of a face gear transmission twin-rotor tandem helicopter provided by the present invention; Figure 5 Schematic diagram of the structure of the rear reducer in the power transmission system of a face gear transmission twin-rotor tandem helicopter provided by the present invention; Wherein: 1. Left head reducer; 101. Left head driving cylindrical gear; 12. Left head driven face gear; 13. Left main transmission shaft; 2. Right head reducer; 21. Right head driving cylindrical gear; 22. Right head driven face gear; 23. Right main transmission shaft; 3. Combining reducer; 31. Combining right driving cylindrical gear; 32. Combining rear driven face gear; 33. Combining front driven face gear; 34. Combining left driving cylindrical gear; 4. Front reducer; 41. Front rotor shaft; 42. Front driving cylindrical gear; 43. Front driven face gear; 5. Rear reducer; 51. Rear rotor shaft; 52. Rear driving cylindrical gear; 53. Rear driven face gear; 6. Front synchronizing shaft; 7. Rear synchronizing shaft; 8. Left engine; 9. Right engine; 10. Front rotor; 11. Rear rotor. Detailed implementation manners

[0024] In order 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. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected 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 shall fall within the protection scope of the present invention.

[0026] It should be noted that: like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for differential description and cannot be construed as indicating or implying relative importance.

[0028] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0029] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "coupled" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] To solve the technical defects mentioned in the background art, this embodiment provides a face gear transmission dual-rotor tandem helicopter power transmission system and a gyrocopter. The following further describes the present invention in detail with reference to the drawings: In a first aspect, the embodiments of the present invention provide a face gear transmission dual-rotor tandem helicopter power transmission system, such as Figures 1-5As shown, it includes two groups of head reducers, which are symmetrically arranged and connected to each other through the parallel reducer 3; a driving device, each of which is provided with a driving device, and the driving device and the head reducer are axially perpendicular; a synchronous shaft, which is arranged in the parallel reducer 3, is axially parallel to the two groups of head reducers and the driving device, one end of which is connected to the front reducer 4, and the other end is connected to the rear reducer 5, and the front reducer 4 and the rear reducer 5 are axially parallel. In order to achieve a large transmission ratio, the transmission system of the traditional twin-rotor tandem helicopter often adopts multi-stage gear transmission, resulting in a large number of transmission stages and complicated mechanical parts. The present technical solution adopts face gear transmission, which can realize power transmission and deceleration more efficiently through the unique transmission characteristics of the face gear. Under the premise of meeting the requirements of a large transmission ratio, the number of transmission stages and the number of mechanical parts are reduced, which helps to reduce the complexity of the transmission system, reduce the possible failure points due to too many parts, and improve the overall reliability of the system.

[0031] In the structural composition, the two groups of head reducers are symmetrically arranged and connected through the parallel reducer 3, which makes the power transmission more balanced, reduces the overall weight of the helicopter, and improves the flight performance and load-bearing capacity of the helicopter; the drive device is perpendicular to the axis of the head reducer, and the synchronization shaft is parallel to the axis of the two groups of head reducers and the drive device, and is respectively connected to the front reducer 4 and the rear reducer 5, which can more directly and efficiently transmit power from the drive device to the front rotor 10 and the rear rotor 11, reducing the energy loss in the power transmission process, improving the transmission efficiency, and enabling the helicopter to more effectively utilize the power generated by the engine, thereby improving the flight performance and endurance.

[0032] Further, the parallel car reducer 3 includes two parallel car driven face gears, specifically the parallel car front driven face gear 33 and the parallel car rear driven face gear 32. The parallel car front driven face gear 33 and the parallel car rear driven face gear 32 are arranged opposite to each other, and the two ends of the parallel car front driven face gear 33 and the parallel car rear driven face gear 32 are connected by cylindrical gears, and the cylindrical gears are meshed with the two sets of head reducers. As can be seen from the figure, the cylindrical gears include the parallel car right driving cylindrical gear 31 and the parallel car left driving cylindrical gear 34. The relative arrangement of the parallel car right driving cylindrical gear 31 and the parallel car left driving cylindrical gear 34 makes the transmission between the parallel car front driven face gear 33 and the parallel car rear driven face gear 32 more reliable. The synchronous shaft includes a front synchronous shaft 6 and a rear synchronous shaft 7. One end of the front synchronous shaft 6 is connected to the front reducer 4, and the other end is connected to the front driven face gear 33 of the parallel vehicle; one end of the rear synchronous shaft 7 is connected to the rear reducer 5, and the other end is connected to the rear driven face gear 32 of the parallel vehicle.

[0033] Among them, the front reducer 4 includes a front driving spur gear 42, which is arranged at the end of the front synchronizing shaft 6. A front driven face gear 43 is meshed with the bottom of the front driving spur gear 42. The front driven face gear 43 is arranged outside the front rotor shaft 41. The top of the front rotor shaft 41 is connected with a front rotor 10. The rear reducer 5 includes a rear driving spur gear 52, which is arranged at the end of the rear synchronizing shaft 7. A rear driven face gear 53 is meshed with the top of the rear driving spur gear 52. The rear driven face gear 53 is arranged outside the rear rotor shaft 51. The top of the rear rotor shaft 51 is connected with a rear rotor 11. The front driving spur gear 42 is arranged at the end of the front synchronizing shaft 6 and meshed with the bottom of the front driven face gear 43, which can ensure the efficient and accurate transmission of power from the front synchronizing shaft 6 to the front rotor shaft 41. Similarly, in the rear reducer 5, the rear driving spur gear 52 is meshed with the top of the rear driven face gear 53 to realize the reliable transmission of power from the rear synchronizing shaft 7 to the rear rotor shaft 51. In this structural composition, the meshing mode of the spur gear and the face gear has high transmission efficiency and transmission accuracy, reducing the energy loss and error accumulation during the power transmission process, enabling the front and rear rotors to obtain stable and expected power input, thus ensuring the normal flight of the helicopter.

[0034] In this embodiment, the two sets of head reducers have the same structure. The head reducer includes a head driving spur gear, which is arranged at the driving end of the driving device. A head driven face gear is meshed with the outside of the head driving spur gear. A main transmission shaft is arranged in the head driven face gear. The end of the main transmission shaft is fixedly connected with the parallel reducer 3. Specifically, one set is the left head reducer 1, and the other set is the right head reducer 2. The left head reducer 1 includes a left head driving spur gear 101, a left head driven face gear 12, and a left main transmission shaft 13. The right head reducer 2 includes a right head driving spur gear 21, a right head driven face gear 22, and a right main transmission shaft 23. Among them, the axial direction between the left head driving spur gear 101 and the left head driven face gear 12 is perpendicular, and the axial direction between the right head driving spur gear 21 and the right head driven face gear 22 is perpendicular.

[0035] In this embodiment, the axial direction between the main transmission shaft and the head driven face gear coincides. Specifically, the main transmission shaft includes a left main transmission shaft 13 and a right main transmission shaft 23, and the head driven face gear includes a left head driven face gear 12 and a right head driven face gear 22. Among them, the axial direction between the left main transmission shaft 13 and the left head driven face gear 12 coincides, and the axial direction between the right main transmission shaft 23 and the right head driven face gear 22 coincides.

[0036] In this embodiment, the driving device is an engine. The engine includes a left engine 8 and a right engine 9. The left engine 8 is connected with the left head driving spur gear 101, and the right engine 9 is connected with the right head driving spur gear 21. The rear reducer 5 is located between the left engine 8 and the right engine 9.

[0037] In this embodiment, the front reduction gear 4 and the rear reduction gear 5 are axially perpendicular to the synchronization shaft.

[0038] During application, the left engine 8 provides high-speed and low-torque power, and the left head reduction gear 1 is used to achieve commutation, speed reduction, and torque increase. The right engine 9 provides high-speed and low-torque power, and the right head reduction gear 2 is used to achieve commutation, speed reduction, and torque increase. The left engine 8 and the right engine 9 have exactly the same structure, and the left head reduction gear 1 and the right head reduction gear 2 have exactly the same structure, and both are symmetrically arranged about the helicopter's heading center axis.

[0039] The two-way power is commutated, speed-reduced, torque-increased, and then confluent and split through the parallel reduction gear 3. One of the split power passes through the front synchronization shaft 6 and the front reduction gear 4 for further commutation, speed reduction, and torque increase, and finally is output through the front rotor 10; the other power passes through the rear synchronization shaft 7 and the rear reduction gear 5 for further commutation, speed reduction, and torque increase, and finally is output through the rear rotor 11. The left head reduction gear 1 consists of a left head driving cylindrical gear 101, a left head driven face gear 12, and a left main transmission shaft 13; the right head reduction gear 2 consists of a right head driving cylindrical gear 21, a right head driven face gear 22, and a right main transmission shaft 23. The left head reduction gear 1 and the right head reduction gear 2 have exactly the same structure and are symmetrically arranged.

[0040] The parallel reduction gear 3 consists of a parallel right driving cylindrical gear 31, a parallel rear driven face gear 32, a parallel front driven face gear 33, and a parallel left driving cylindrical gear 34. The parallel right driving cylindrical gear 31 and the parallel left driving cylindrical gear 34 have exactly the same structure and are coaxially arranged. The parallel rear driven face gear 32 and the parallel front driven face gear 33 have exactly the same structure and are coaxially arranged face to face. The parallel right driving cylindrical gear 31 and the right head driven face gear 22 are installed on the right main transmission shaft 23. The parallel left driving cylindrical gear 34 and the left head driven face gear 12 are installed on the left main transmission shaft 13. The parallel rear driven face gear 32 is installed on the rear synchronization shaft 7. The parallel front driven face gear 33 is installed on the front synchronization shaft 6.

[0041] The front reduction gear 4 includes a front rotor shaft 41, a front driving cylindrical gear 42, and a front driven face gear 43. The front driven face gear 43 and the front rotor 10 are installed on the front rotor shaft 41, and the front driving cylindrical gear 42 is installed on the front synchronization shaft 6. The rear reduction gear 5 includes a rear rotor shaft 51, a rear driving cylindrical gear 52, and a rear driven face gear 53. The rear driven face gear 53 and the rear rotor 11 are installed on the rear rotor shaft 51, and the rear driving cylindrical gear 52 is installed on the rear synchronization shaft 7. The front driving cylindrical gear 42 and the rear driving cylindrical gear 52 have exactly the same structure, and the front driven face gear 43 and the rear driven face gear 53 have exactly the same structure. In order to ensure that the rotation directions of the front rotor 10 and the rear rotor 11 are opposite, the front driving cylindrical gear 42 is above the front driven face gear 43, and the rear driving cylindrical gear 52 is below the rear driven face gear 53.

[0042] The power transmission system of the face gear transmission twin-rotor tandem helicopter provided by the present invention entirely adopts face gear transmission. The high-speed and low-torque power of the left engine 8 and the right engine 9 respectively undergoes the first commutation and torque increase through the left head reducer 1 and the right head reducer 2. After the power is combined through the parallel reducer 3 and then split, the second commutation and torque increase are achieved. One way of the power passes through the front synchronizing shaft 6 and the front reducer 4, and the other way of the power passes through the rear synchronizing shaft 7 and the rear reducer 5 for the third torque increase and commutation. Finally, the low-speed and high-torque power is output through the front rotor 10 and the rear rotor 11.

[0043] Since in multi-stage gear transmission, the transmission ratio of a single-stage face gear is large, the number of transmission stages can be effectively reduced. Compared with the transmission system of the American Boeing Vertol 107 twin-rotor tandem helicopter, the present invention changes the four-stage gear transmission composed of herringbone gears, cylindrical gears, bevel gears and planetary gears into a three-stage face gear transmission, reduces the number of transmission stages, effectively reduces the number of parts of the transmission system, and improves the reliability of the transmission system.

[0044] In a second aspect, a gyroplane is provided, including a gyroplane body, and the gyroplane body is installed with the power transmission system of the face gear transmission twin-rotor tandem helicopter as described above.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the scope of its protection. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the present invention, various changes, modifications or equivalent replacements can still be made to the specific implementation manners of the invention. However, these changes, modifications or equivalent replacements are all within the scope of the claims of the invention pending approval.

Claims

1. A power transmission system for a coaxial contra-rotating helicopter with face gear drive, characterized in that, include: Two sets of head reducers are symmetrically arranged and connected to each other through a parallel reducer transmission; A driving device, one driving device is provided on each of the two groups of head reducers, and the driving device and the head reducer are axially perpendicular; The synchronous shaft is arranged in the parallel car reducer, and is axially parallel to the two sets of head reducers and the driving device. One end of the synchronous shaft is drivingly connected to the front reducer, and the other end is connected to the rear reducer. The front reducer and the rear reducer are axially parallel to each other.

2. The face gear transmission dual-rotor tandem helicopter power transmission system according to claim 1, characterized in that, The parallel car reducer comprises: Two parallel driven face gears are arranged opposite to each other, and both ends of the two parallel driven face gears are connected by cylindrical gears, and the cylindrical gears are meshed with two sets of head reducers; The synchronous shaft comprises: A front synchronous shaft and a rear synchronous shaft, wherein one end of the front synchronous shaft is connected to the front reducer, and the other end is connected to one of the parallel driven face gears; One end of the rear synchronous shaft is connected to the rear reducer, and the other end is connected to another parallel driven face gear.

3. The face gear transmission dual-rotor tandem helicopter power transmission system according to claim 2, characterized in that, The front reducer comprises: A front driving cylindrical gear is arranged at the end of the front synchronization shaft, and a front driven face gear is meshed at its bottom. The front driven face gear is arranged on the outside of the front rotor shaft, and the top of the front rotor shaft is connected to the front rotor; The rear reducer comprises: The rear driving cylindrical gear is arranged at the end of the rear synchronous shaft, and the top of the rear driving cylindrical gear is meshed with a rear driven face gear, which is arranged on the outside of the rear rotor shaft, and the top of the rear rotor shaft is connected with the rear rotor.

4. The face gear transmission dual-rotor tandem helicopter power transmission system according to claim 1, wherein, The two groups of head reducers have the same structure, and the head reducers include: The head driving cylindrical gear is arranged on the driving end of the driving device, and the head driven face gear is meshed on its outer side. The head driven face gear is provided with a main transmission shaft, and the end of the main transmission shaft is fixedly connected to the parallel car reducer.

5. The face gear drive dual-rotor tandem helicopter power transmission system according to claim 4, wherein, The axial directions of the head driving cylindrical gear and the head driven face gear are perpendicular.

6. The face gear drive dual-rotor tandem helicopter power transmission system according to claim 4, characterized in that, The main transmission shaft and the head driven face gear are axially overlapped.

7. The face gear drive dual-rotor tandem helicopter power transmission system according to claim 1 or 4, characterized in that, The driving device is an engine.

8. The face gear transmission dual-rotor tandem helicopter power transmission system according to claim 1, characterized in that, The rear reducer is located between the two driving devices.

9. The face gear drive dual-rotor tandem helicopter power transmission system according to claim 1, characterized in that, The front speed reducer and the rear speed reducer are axially perpendicular to the synchronization shaft.

10. A gyrocopter, comprising a gyrocopter body, characterized in that, The rotorcraft body is equipped with a face gear transmission twin-rotor tandem helicopter power transmission system as described in any one of claims 1-9.

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