Transmission system and unmanned helicopter

Abstract

The utility model embodiment provides a kind of transmission system and unmanned helicopter, it is related to unmanned helicopter structure technical field.Transmission system includes main rotor shaft, tail shaft and transmission component.First transmission gear is installed to main rotor shaft, second transmission gear is installed to tail shaft, second transmission gear is engaged with first transmission gear, the axis of tail shaft and the axis of main rotor shaft are at angle, transmission component is used to be connected with engine transmission, and with main rotor shaft transmission connection, to transmit the power of engine to main rotor shaft, and it is transmitted to tail shaft by main rotor shaft.The transmission system provided in the application can change the speed of engine into the speed required by rotor without transmission treatment, can adapt to different rated speed engines, simple and stable structure, light weight, easy to overhaul and maintain;At the same time, first transmission gear on main rotor shaft and second transmission gear on tail shaft are engaged, tail shaft and main rotor shaft are separated, and the quick disassembly of tail shaft can be realized.

Description

Technical Field

[0001] This utility model relates to the field of unmanned helicopter structural technology, and more specifically, to a transmission system and an unmanned helicopter. Background Technology

[0002] Unmanned helicopters have been widely used in many fields due to their vertical takeoff and landing (VTOL) capability, hovering capability, and low requirements for takeoff and landing sites.

[0003] Unmanned helicopters need to ensure that the high speed of the engine output shaft can match the operating speed of the rotor blades. Therefore, the transmission system of unmanned helicopters plays a very important role. However, the main rotor shaft in some existing unmanned helicopters is not easy to disassemble and assemble with the tail shaft. Utility Model Content

[0004] The purpose of this invention is to provide a transmission system and an unmanned helicopter that facilitates the disassembly and assembly of the main rotor shaft and the tail shaft.

[0005] The embodiments of this utility model can be implemented as follows:

[0006] In a first aspect, this utility model provides a transmission system, comprising:

[0007] The main rotor shaft is equipped with the first transmission gear.

[0008] The tail shaft is equipped with a second transmission gear, which meshes with the first transmission gear. The axis of the tail shaft forms an angle with the axis of the main rotor shaft.

[0009] The transmission assembly is used to drive the engine and the main rotor shaft to transmit the engine's power to the main rotor shaft, and then to the tail shaft via the main rotor shaft.

[0010] In an optional embodiment, the first transmission gear is a first bevel gear, and the second transmission gear is a second bevel gear that meshes with the first bevel gear.

[0011] In an optional embodiment, one of the first transmission gear and the second transmission gear is a face gear, and the other of the first transmission gear and the second transmission gear is a helical gear or a quasi-hyperboloid gear.

[0012] In an optional embodiment, the transmission assembly includes a driving wheel and a driven wheel that are connected in a transmission manner. The driving wheel is connected to the output shaft of the engine, and the driven wheel is sleeved on the main rotor shaft.

[0013] In an optional embodiment, the transmission assembly further includes an annular synchronous belt, which is sleeved on the driving pulley and the driven pulley, and the driving pulley is connected to the driven pulley via the synchronous belt; and / or

[0014] The radial dimension of the driving wheel is smaller than that of the driven wheel.

[0015] In an optional embodiment, the transmission system further includes a tail rotor shaft, on which a third transmission gear is mounted, and at the end of the tail shaft away from the main rotor shaft, a fourth transmission gear is mounted, which meshes with the third transmission gear, and the axis of the tail rotor shaft forms an angle with the axis of the tail shaft.

[0016] In an optional embodiment, the third transmission gear is a third bevel gear, and the fourth transmission gear is a fourth bevel gear that meshes with the third bevel gear.

[0017] In an optional embodiment, the tail shaft includes a tail drive shaft and a tail drive shaft sleeve. The tail drive shaft passes through the tail drive shaft sleeve and can rotate relative to the tail drive shaft sleeve about its own axis. The second transmission gear is connected to the tail drive shaft.

[0018] In an optional embodiment, a mating bearing is provided between the tail drive shaft and the tail drive shaft sleeve.

[0019] In an optional embodiment, the tail shaft further includes a connecting shaft, a mating sleeve, and a positioning shaft. The second transmission gear is connected to the tail drive shaft via the connecting shaft. The connecting shaft and the positioning shaft are arranged in sequence. The mating sleeve is fitted onto the connecting shaft, the positioning shaft, and the tail drive shaft and is fixedly connected to the connecting shaft, the positioning shaft, and the tail drive shaft. The positioning shaft extends into the tail drive shaft. A limiting part is provided at one end of the positioning shaft near the connecting shaft. The two ends of the limiting part abut against the tail drive shaft and the mating sleeve, respectively.

[0020] Secondly, this utility model provides an unmanned helicopter, including the transmission system of any of the aforementioned embodiments.

[0021] The beneficial effects of this utility model embodiment include: The transmission system provided by this utility model embodiment includes a main rotor shaft, a tail shaft, and a transmission assembly. A first transmission gear is mounted on the main rotor shaft, and a second transmission gear is mounted on the tail shaft. The second transmission gear meshes with the first transmission gear. The axis of the tail shaft forms an angle with the axis of the main rotor shaft. The transmission assembly is used for transmission connection with the engine and the main rotor shaft to transmit the engine's power to the main rotor shaft, and then to the tail shaft via the main rotor shaft. The transmission system provided by this application can convert the engine's (e.g., engine speed) rotation speed into the rotor speed required without the need for a gearbox. It can adapt to engines with different rated speeds, has a simple and stable structure, is lightweight, and is easy to inspect and maintain. Simultaneously, the meshing of the first transmission gear on the main rotor shaft and the second transmission gear on the tail shaft facilitates the separation of the tail shaft from the main rotor shaft, enabling quick assembly and disassembly of the tail shaft from the main rotor shaft. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the transmission system provided in this embodiment;

[0024] Figure 2 This is a cross-sectional schematic diagram of the transmission system provided in this embodiment;

[0025] Figure 3 for Figure 2 A magnified view of a portion of the image.

[0026] Icons: 1-Transmission system; 110-Main rotor shaft; 111-First transmission gear; 120-Tail shaft; 121-Second transmission gear; 122-Tail drive shaft sleeve; 123-Tail drive shaft; 124-Matching bearing; 125-Fourth transmission gear; 126-Connecting shaft; 1261-Boss; 127-Connecting sleeve; 128-Shim; 130-Transmission assembly; 131-Drive wheel; 132-Driven wheel; 133-Synchronous belt; 140-Engine; 150-Tail rotor shaft; 151-Third transmission gear; 160-Matching sleeve; 170-Positioning shaft; 171-Limiting part; 180-Support ring. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed during use, they are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model.

[0031] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0032] It should be noted that, where there is no conflict, the features in the embodiments of this utility model can be combined with each other.

[0033] The following describes in detail, with reference to the accompanying drawings, a transmission system and an unmanned helicopter provided by this utility model, along with their specific structure and corresponding technical effects.

[0034] Please refer to Figures 1-2 The transmission system 1 provided in this embodiment of the present invention includes a main rotor shaft 110, a tail shaft 120, and a transmission assembly 130. A first transmission gear 111 is mounted on the main rotor shaft 110, and a second transmission gear 121 is mounted on the tail shaft 120. The second transmission gear 121 meshes with the first transmission gear 111. The axis of the tail shaft 120 forms an angle with the axis of the main rotor shaft 110. The transmission assembly 130 is used for transmission connection with an engine 140 and is also connected to the main rotor shaft 110 to transmit power from the engine 140 to the main rotor shaft 110, and then from the main rotor shaft 110 to the tail shaft 120. In other words, the power of the engine 140 can be transmitted sequentially through the transmission assembly 130 and the main rotor shaft 110 to the tail shaft 120.

[0035] It should be noted that in this embodiment, the axis of the main rotor shaft 110 is coaxial with the axis of the first transmission gear 111, and the axis of the tail shaft 120 is coaxial with the axis of the second transmission gear 121. In other words, the axis of the first transmission gear 111 and the axis of the second transmission gear 121 are also at an angle.

[0036] In detail, in this embodiment, the axis of the main rotor shaft 110 is perpendicular to the axis of the tail shaft 120. It should be noted that the perpendicularity in this embodiment is not limited to a strict sense of perpendicularity; it is sufficient that the two axes are approximately perpendicular.

[0037] The engine 140 drives the transmission assembly 130 to move, which in turn drives the main rotor shaft 110 to rotate. At this time, the main rotor mounted on the main rotor shaft 110 rotates along with the main rotor shaft 110 to provide lift for the unmanned helicopter. Similarly, the first transmission gear 111 mounted on the main rotor shaft 110 also rotates along with the main rotor shaft 110. The first transmission gear 111 drives the second transmission gear 121 to rotate, thereby transmitting the power of the engine 140 to the tail shaft 120.

[0038] Understandably, since the main rotor shaft 110 meshes with the second transmission gear 121 on the tail shaft 120 through the first transmission gear 111, it is easy to separate the tail shaft 120 from the main rotor shaft 110, and the tail shaft 120 and the main rotor shaft 110 can be quickly disassembled and assembled.

[0039] In this embodiment, the torque of the main rotor shaft 110 can be transmitted to the tail shaft 120 through the first transmission gear 111 and the second transmission gear 121, thereby transmitting the rotational speed to the tail rotor connected to the tail shaft 120. The rotational speed of the tail rotor connected to the tail shaft 120 can be adjusted by adjusting the number of teeth of the first transmission gear 111 and the second transmission gear 121.

[0040] Optionally, in this embodiment, the first transmission gear 111 is a first bevel gear, and the second transmission gear 121 is a second bevel gear meshing with the first bevel gear. It is understood that the first and second bevel gears can stably achieve torque reversal between the main rotor shaft 110 and the tail shaft 120. It is also understood that bevel gears can achieve power transmission between vertical shafts within a relatively small space and have high transmission efficiency.

[0041] In this configuration, the radial dimension of the first bevel gear is larger than that of the second bevel gear; that is, the first bevel gear is a large bevel gear, and the second bevel gear is a small bevel gear. The main rotor shaft 110 is typically powered by an engine or electric motor, providing high-speed, low-torque output. The tail rotor, however, requires lower speeds and higher torque to counteract the reverse torque generated by the main rotor. The larger radial dimension of the first bevel gear (driving bevel gear) means it has more teeth; the smaller radial dimension of the second bevel gear (driven bevel gear) means it has fewer teeth. Therefore, the transmission between the first and second bevel gears achieves a speed reduction and torque increase effect, enabling the tail rotor to obtain sufficient torque.

[0042] Optionally, in some embodiments, one of the first transmission gear 111 and the second transmission gear 121 is a face gear. It should be noted that a face gear is a special type of gear whose teeth are distributed on the end face, rather than on the circumference as in traditional cylindrical gears. Face gears are typically used in conjunction with helical gears or hypoid gears to achieve efficient vertical shaft transmission.

[0043] For example, one of the first transmission gear 111 and the second transmission gear 121 may be a face gear and the other a helical gear, or the other may be a hypoid gear. The combination of a face gear and a helical gear or a hypoid gear can realize the reversal of power transmission between two shafts, and has the advantages of high efficiency, compact design and smooth operation.

[0044] In detail, in this embodiment, the tail shaft 120 includes a tail drive shaft 123 and a tail drive shaft sleeve 122. The tail drive shaft 123 passes through the tail drive shaft sleeve 122 and can rotate relative to the tail drive shaft sleeve 122 around its own axis. The second transmission gear 121 is connected to the tail drive shaft 123.

[0045] Understandably, the tail drive shaft sleeve 122 can serve to install and fix the tail drive shaft 123. Furthermore, since part of the tail drive shaft 123 is located inside the tail drive shaft sleeve 122, the tail drive shaft sleeve 122 can also protect the tail drive shaft 123, effectively reducing the impact of the external environment on the tail drive shaft 123, thereby ensuring the power transmission efficiency between the main rotor shaft 110 and the tail drive shaft 123.

[0046] In other words, when the engine 140 drives the transmission assembly 130 to move, the transmission assembly 130 transmits power to the main rotor shaft 110, which in turn drives the main rotor shaft 110 to rotate. At this time, the main rotor mounted on the main rotor shaft 110 can rotate along with the rotation of the main rotor shaft 110. The first transmission gear 111 will rotate along with the rotation of the main rotor shaft 110. At the same time, the first transmission gear 111 will drive the second transmission gear 121 to rotate, thereby transmitting the power of the engine 140 to the tail drive shaft 123 of the tail shaft 120.

[0047] Please continue to refer to this. Figures 1-2 Optionally, in this embodiment, a mating bearing 124 is provided between the tail drive shaft 123 and the tail drive shaft sleeve 122. The tail drive shaft 123 passes through the mating bearing 124 and can rotate relative to the mating bearing 124 around its own axis. It can be understood that the mating bearing 124 can provide effective support for the tail drive shaft 123, preventing deformation caused by the excessive length of the tail drive shaft 123. The arrangement of the mating bearing 124 can also make the rotation of the tail drive shaft 123 smoother.

[0048] To further ensure support for the tail drive shaft 123, multiple mating bearings 124 can be provided, with these bearings spaced apart axially along the tail drive shaft 123. It should be noted that "multiple" in this embodiment can be understood as two or more bearings.

[0049] In detail, in this embodiment, the number of mating bearings 124 is three. It can be understood that when the number of mating bearings 124 is large, the support for the tail drive shaft 123 can be improved, effectively preventing the tail drive shaft 123 from deforming. However, a large number of mating bearings 124 will also increase the weight of the transmission system 1. Therefore, in this embodiment, the number of mating bearings 124 is three, which can ensure that the transmission system 1 is not too heavy while also ensuring the support for the tail drive shaft 123.

[0050] Please refer to Figure 3 Optionally, in some embodiments, the tail shaft 120 further includes a connecting shaft 126, which passes through and is fixedly connected to the tail drive shaft 123. The second drive gear 121 is connected to the tail drive shaft 123 via the connecting shaft 126. Specifically, when the second drive gear 121 is a second bevel gear, the second bevel gear is sleeved on the connecting shaft 126 and fixedly connected to it. Through the connecting shaft 126, second bevel gears of different sizes can be mounted on the tail drive shaft 123.

[0051] Optionally, to facilitate the installation of the second bevel gear, the second bevel gear has a shaft portion that is sleeved on the connecting shaft 126. A boss 1261 protrudes from the outer peripheral wall of the connecting shaft 126, which limits the axial installation distance of the shaft portion on the connecting shaft 126. To ensure the installation stability of the second bevel gear, a shim 128 is provided between the shaft portion and the boss 1261. That is, the shim 128 is sleeved on the connecting shaft 126, and both sides of the shim 128 abut against the shaft portion and the boss 1261, respectively.

[0052] In some embodiments, to ensure the rotational stability of the second bevel gear, the tail shaft 120 may further include a connecting sleeve 127. The connecting sleeve 127 may be sleeved on the shaft portion and / or the boss 1261, and the connecting sleeve 127 extends at least partially into the tail drive shaft sleeve 122. The second bevel gear can rotate relative to the connecting sleeve 127 about its own axis, and the connecting sleeve 127 can provide support for the second bevel gear. To ensure that the connecting sleeve 127 is installed in place, the end wall of the connecting sleeve 127 may have a limiting protrusion that abuts against the end wall of the tail drive shaft sleeve 122, so as to facilitate the quick installation of the connecting sleeve 127 and the tail drive shaft sleeve 122.

[0053] Optionally, the connecting sleeve 127 can be a bearing, and the specific bearing type is not specifically limited here.

[0054] Optionally, to facilitate the installation of the connecting shaft 126 and to reduce the wear of the connecting shaft 126, the tail shaft 120 may also include a mating sleeve 160 and a positioning shaft 170. The connecting shaft 126 and the positioning shaft 170 are arranged sequentially. The mating sleeve 160 can be sleeved on the connecting shaft 126, the positioning shaft 170 and the tail drive shaft 123, and the mating sleeve 160 is fixedly connected to the connecting shaft 126, the positioning shaft 170 and the tail drive shaft 123.

[0055] Optionally, the mating sleeve 160 is keyed to the connecting shaft 126, and the mating sleeve 160 is connected to the positioning shaft 170 and the tail drive shaft 123 by fasteners (including but not limited to threaded fasteners).

[0056] The positioning shaft 170 can extend into the tail drive shaft 123. A limiting part 171 is provided at the end of the positioning shaft 170 near the connecting shaft 126. The two ends of the limiting part 171 abut against the tail drive shaft 123 and the mating sleeve 160, respectively. Specifically, the mating sleeve 160 has a first mating hole and a second mating hole that communicate with each other. The first mating hole matches the shape of the connecting shaft 126, and the second mating hole matches the shape of the tail drive shaft 123. The size of the first mating hole is smaller than the size of the second mating hole, creating a stepped surface at the connection between the first and second mating holes. The limiting part 171 of the positioning shaft 170 is located within the second mating hole of the mating sleeve 160. The end of the limiting part 171 near the tail drive shaft 123 abuts against the end wall of the tail drive shaft 123, and the end of the limiting part 171 away from the tail drive shaft 123 abuts against the stepped surface within the mating sleeve 160.

[0057] Of course, in order to ensure support for the mating sleeve 160, a support ring 180 can also be provided inside the tail shaft 120. The support ring 180 is installed inside the tail drive shaft sleeve 122 and is sleeved on the outer periphery of the mating sleeve 160.

[0058] At this time, when the second bevel gear rotates, it can drive the connecting shaft 126 to rotate. Since the connecting shaft 126 is fixedly connected to the tail drive shaft 123, it can drive the tail drive shaft 123 to rotate.

[0059] In detail, the transmission system 1 also includes a tail rotor shaft 150, on which a third transmission gear 151 is mounted. A fourth transmission gear 125 is mounted at the end of the tail shaft 120 away from the main rotor shaft 110. The fourth transmission gear 125 meshes with the third transmission gear 151. The axis of the tail rotor shaft 150 forms an angle with the axis of the tail shaft 120.

[0060] Similarly, as described above, since the tail shaft 120 meshes with the third transmission gear 151 on the tail rotor shaft 150 through the fourth transmission gear 125, the tail rotor shaft 150 and the tail shaft 120 can be directly separated when disassembling the tail rotor shaft 150 and the tail shaft 120, which facilitates the separation of the tail drive shaft 123 from the main rotor shaft 110.

[0061] Specifically, the aforementioned fourth transmission gear 125 is mounted on the end of the tail drive shaft 123 away from the second transmission gear 121. In this embodiment, the axis of the tail rotor shaft 150 is perpendicular to the axis of the tail shaft 120.

[0062] Optionally, in this embodiment, the third transmission gear 151 is a third bevel gear, and the fourth transmission gear 125 is a fourth bevel gear meshing with the third bevel gear. It is understood that the third and fourth bevel gears can stably achieve torque reversal between the tail rotor shaft 150 and the tail drive shaft 123, thereby transmitting power to the tail rotor shaft 150 connected to the tail drive shaft 123 to drive the tail rotor to rotate. It is understood that bevel gears can achieve power transmission between vertical axes within a relatively small space and also have high transmission efficiency.

[0063] Of course, in other embodiments, the third transmission gear 151 and the fourth transmission gear 125 can also be other types of gears capable of torque reversal, such as a combination of face gears, hyperboloid gears and helical gears.

[0064] Therefore, the third transmission gear 151 and the fourth transmission gear 125 can transmit the torque of the tail drive shaft 123 to the tail rotor shaft 150, and then transmit the rotational speed to the tail rotor connected to the tail rotor shaft 150. The rotational speed of the tail rotor connected to the tail rotor shaft 150 can be adjusted by adjusting the number of teeth of the third bevel gear and the fourth bevel gear.

[0065] In some existing transmission systems, the engine first transmits power to the belt drive, which then transmits the power to the reducer. The reducer then transmits the power to the main rotor shaft 110 and the tail shaft 120 respectively. This transmission method has a complex structure and multiple transmission stages, resulting in a large weight and low transmission efficiency. Furthermore, the reducer requires maintenance, which is inconvenient for daily maintenance in light unmanned helicopters with limited internal space.

[0066] In detail, in this embodiment, the transmission assembly 130 includes a driving wheel 131 and a driven wheel 132 connected by a drive wheel. The driving wheel 131 is connected to the output shaft of the engine 140, and the driven wheel 132 is sleeved on the main rotor shaft 110. That is to say, in this embodiment, the engine 140 can transmit power to the main rotor shaft 110 through the driving wheel 131 and the driven wheel 132, and then transmit power to the tail drive shaft 123 through the main rotor shaft 110. The required rotational speed of the rotor can be obtained without a reducer. The transmission method is simple, the ineffective weight is small, and the number of transmission stages is small, which can effectively improve the transmission efficiency. In this embodiment, power is transmitted through the driving wheel 131, the driven wheel 132, the first bevel gear, and the second bevel gear, eliminating the complex reducer and making it easier for users to maintain the transmission system 1.

[0067] In detail, the transmission assembly 130 also includes an annular synchronous belt 133, which is sleeved on the driving pulley 131 and the driven pulley 132. The driving pulley 131 is connected to the driven pulley 132 via the synchronous belt 133. It can be understood that the synchronous belt 133 not only transmits power but also isolates vibration.

[0068] In detail, in this embodiment, the radial dimension of the drive pulley 131 is smaller than that of the driven pulley 132. That is to say, under the action of the synchronous belt 133, the speed of the engine 140 can be reduced. By reasonably selecting the drive pulley 131 and the driven pulley 132, the speed of the engine 140 can be reduced to the speed required by the main rotor on the main rotor shaft 110, thus eliminating the need for the existing gearbox.

[0069] Furthermore, by adjusting the length of the timing belt 133, the position of the main rotor shaft 110 can be adjusted to coincide with the center of gravity of the unmanned helicopter. Through the arrangement of the timing belt 133, the drive pulley 131 and the driven pulley 132, the complexity of the transmission system 1 and some unnecessary weight can be reduced, the reliability of the transmission system 1 can be improved, and maintenance of the existing reducer can be avoided.

[0070] Optionally, both the outer peripheral walls of the driving wheel 131 and the driven wheel 132 may be provided with transmission teeth, and the synchronous belt 133 shall engage with the transmission teeth of the driving wheel 131 and the driven wheel 132.

[0071] That is, by adjusting the number of teeth on the drive wheel 131 and the driven wheel 132, the speed of the engine 140 can be reduced to the speed required by the main rotor shaft 110 during transmission.

[0072] In summary, the transmission system 1 provided by this embodiment of the present invention includes a main rotor shaft 110, a tail shaft 120, and a transmission assembly 130. The main rotor shaft 110 is equipped with a first transmission gear 111, and the tail shaft 120 is equipped with a second transmission gear 121. The second transmission gear 121 meshes with the first transmission gear 111. The axis of the tail shaft 120 forms an angle with the axis of the main rotor shaft 110. The transmission assembly 130 is used for transmission connection with the engine 140, and is also transmissionally connected to the main rotor shaft 110 to transmit power from the engine 140 to the main rotor shaft 110, and then from the main rotor shaft 110 to the tail shaft 120. This facilitates the separation of the tail shaft 120 from the main rotor shaft 110, enabling quick assembly and disassembly of the tail shaft 120 from the main rotor shaft 110.

[0073] This utility model embodiment also provides an unmanned helicopter, which includes the aforementioned transmission system 1. The transmission system 1 includes a main rotor shaft 110, a tail shaft 120, and a transmission assembly 130. The main rotor shaft 110 is equipped with a first transmission gear 111, and the tail shaft 120 is equipped with a second transmission gear 121. The second transmission gear 121 meshes with the first transmission gear 111. The axis of the tail shaft 120 forms an angle with the axis of the main rotor shaft 110. The transmission assembly 130 is used for transmission connection with the engine 140 and is also transmission connection with the main rotor shaft 110 to transmit the power of the engine 140 to the main rotor shaft 110, and then to the tail shaft 120 via the main rotor shaft 110. The transmission assembly 130 includes a drive pulley 131, a driven pulley 132, and a timing belt 133. The drive pulley 131 is connected to the output shaft of the engine 140, the driven pulley 132 is sleeved on the main rotor shaft 110, and the timing belt 133 is sleeved on the drive pulley 131 and the driven pulley 132. The drive pulley 131 is connected to the driven pulley 132 via the timing belt 133. The transmission system 1 provided in this embodiment transmits power through the drive pulley 131, the driven pulley 132, the timing belt 133, the first bevel gear, and the second bevel gear, eliminating the need for a complex reducer. The transmission method is simple, the number of transmission stages is small, and the transmission efficiency is effectively improved. At the same time, the complexity of the transmission system 1 and some unnecessary weight are reduced, improving the reliability of the transmission system 1. Maintenance of existing reducers is also avoided. The position of the rotor shaft can be adjusted to coincide with the center of gravity of the unmanned helicopter by adjusting the length of the timing belt 133. Furthermore, it can be adapted to engines 140 with different rated speeds and main rotors and tail rotors of different specifications.

[0074] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model.

Claims

1. A transmission system, characterized in that, include: The main rotor shaft is equipped with a first transmission gear. The tail shaft is equipped with a second transmission gear, which meshes with the first transmission gear. The axis of the tail shaft forms an angle with the axis of the main rotor shaft. A transmission assembly is provided for transmission connection with the engine and the main rotor shaft, so as to transmit the power of the engine to the main rotor shaft and then to the tail shaft via the main rotor shaft.

2. The transmission system according to claim 1, characterized in that: The first transmission gear is a first bevel gear, and the second transmission gear is a second bevel gear that meshes with the first bevel gear.

3. The transmission system according to claim 1, characterized in that: One of the first transmission gear and the second transmission gear is a face gear, and the other of the first transmission gear and the second transmission gear is a helical gear or a quasi-hyperboloid gear.

4. The transmission system according to claim 1, characterized in that: The transmission assembly includes a driving wheel and a driven wheel that are connected by transmission. The driving wheel is connected to the output shaft of the engine, and the driven wheel is sleeved on the main rotor shaft.

5. The transmission system according to claim 4, characterized in that: The transmission assembly further includes an annular synchronous belt, which is sleeved on the driving pulley and the driven pulley, and the driving pulley is connected to the driven pulley via the synchronous belt; and / or The radial dimension of the driving wheel is smaller than that of the driven wheel.

6. The transmission system according to any one of claims 1-5, characterized in that: The transmission system also includes a tail rotor shaft, on which a third transmission gear is mounted. A fourth transmission gear is mounted at the end of the tail shaft away from the main rotor shaft. The fourth transmission gear meshes with the third transmission gear. The axis of the tail rotor shaft forms an angle with the axis of the tail shaft.

7. The transmission system according to claim 6, characterized in that: The third transmission gear is a third bevel gear, and the fourth transmission gear is a fourth bevel gear that meshes with the third bevel gear.

8. The transmission system according to any one of claims 1-5, characterized in that: The tail shaft includes a tail drive shaft and a tail drive shaft sleeve. The tail drive shaft passes through the tail drive shaft sleeve and can rotate relative to the tail drive shaft sleeve around its own axis. The second transmission gear is connected to the tail drive shaft.

9. The transmission system according to claim 8, characterized in that: A mating bearing is provided between the tail drive shaft and the tail drive shaft sleeve.

10. The transmission system according to claim 8, characterized in that: The tail shaft also includes a connecting shaft, a mating sleeve, and a positioning shaft. The second transmission gear is connected to the tail drive shaft through the connecting shaft. The connecting shaft and the positioning shaft are arranged in sequence. The mating sleeve is sleeved on the connecting shaft, the positioning shaft, and the tail drive shaft and is fixedly connected to the connecting shaft, the positioning shaft, and the tail drive shaft. The positioning shaft extends into the tail drive shaft. A limiting part is provided at one end of the positioning shaft near the connecting shaft. The two ends of the limiting part abut against the tail drive shaft and the mating sleeve, respectively.

11. An unmanned helicopter, characterized in that, Includes the transmission system as described in any one of claims 1-10.

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