Variable-speed transmission system and crossed double-rotor helicopter

Abstract

The utility model discloses a variable-speed transmission system and a crossed double-rotor helicopter, the variable-speed transmission system comprises a first input shaft, a first clutch and a first output shaft, and the first input shaft is connected with the first output shaft through the first clutch; the speed changing device comprises a first gear train mechanism, a second gear train mechanism and a second clutch, the first gear train mechanism is connected with the second gear train mechanism through the second clutch, the input end of the first gear train mechanism is connected with the first input shaft, and the output end of the second gear train mechanism is connected with the first output shaft; and at least one of the first gear train mechanism and the second gear train mechanism is a speed reducing mechanism. The power output path of the first input shaft is changed through connection or disconnection of the first clutch and the second clutch, and the rotating speeds output by the first output shaft are different. According to the high-speed helicopter adopting the variable-speed transmission system, the purpose of reducing the rotating speed of the rotor wing through the variable-speed transmission system is achieved, and the influence of blade shock waves on the forward side of the rotor wing is reduced.

Description

Technical Field

[0001] This application relates to the field of engine technology, and in particular to a variable speed transmission system and a cross-rotor helicopter. Background Technology

[0002] The advancing blades of high-speed helicopters can generate shock waves because the rotor speed is too high, causing the blade tip speed to approach or exceed the sound wave. The rotor speed needs to be reduced to solve the above problem.

[0003] In related technologies, rotor speed can be reduced by changing the engine speed and the transmission system speed. However, the normal operating speed range of an engine is relatively small, and the reduction in rotor speed by reducing the engine speed is extremely limited. Therefore, it is essential to reduce rotor speed by changing the transmission system.

[0004] Therefore, how to reduce rotor speed through the transmission system and reduce the impact of shock waves from the advancing blades is the key to the development of high-speed helicopters. Utility Model Content

[0005] This application proposes a variable speed transmission system to reduce rotor speed and thus reduce the impact of shock waves from the advancing blades. This application also proposes a cross-rotor helicopter with the aforementioned variable speed transmission system.

[0006] To achieve the above objectives, this application provides a variable speed transmission system, including a first input shaft, a first clutch, and a first output shaft, wherein the first input shaft is connected to the first output shaft via the first clutch;

[0007] It also includes a transmission device, at least one of which comprises a first gear train mechanism, a second gear train mechanism, and a second clutch. The first gear train mechanism is connected to the second gear train mechanism via the second clutch.

[0008] The input end of the first gear train mechanism is connected to the first input shaft, and the output end of the second gear train mechanism is connected to the first output shaft. At least one of the first gear train mechanism and the second gear train mechanism is a speed reduction mechanism to reduce the output speed of the first output shaft.

[0009] When the rotational speed of the first input shaft is less than the preset speed, the first clutch engages and the second clutch disengages.

[0010] When the rotational speed of the first input shaft is equal to or greater than a preset speed, the first clutch disengages and the second clutch engages.

[0011] Preferably, in the above-described variable speed transmission system, the first gear train mechanism includes a first input gear, a first output gear, and a second output shaft.

[0012] The first input gear is disposed at the input end of the first input shaft, the first output gear is installed at the input end of the second output shaft, the output end of the second output shaft is connected to the second clutch, the first output gear meshes with the first input gear, and the number of teeth of the first output gear is greater than or equal to the number of teeth of the first input gear.

[0013] And / or,

[0014] The second gear train mechanism includes a second input gear, a second output gear, and a second input shaft.

[0015] The input end of the second input shaft is connected to the second clutch, the output end of the second input shaft is provided with the second input gear, the second output gear is provided on the first output shaft, the second output gear meshes with the second input gear, and the number of teeth of the second output gear is greater than or equal to the number of teeth of the second input gear.

[0016] Preferably, in the above-mentioned variable speed transmission system, the transmission ratio between the first output gear and the first input gear is the same as or different from the transmission ratio between the second output gear and the second input gear.

[0017] Preferably, in the above-described variable speed transmission system, at least one of the first input shaft, the second input shaft, the first output shaft, and the second output shaft is a hollow shaft.

[0018] Preferably, in the above-mentioned variable speed transmission system, both the hubs of the first output gear and the first input gear are provided with weight-reducing grooves and / or reinforcing ribs.

[0019] And / or,

[0020] The hubs of the second output gear and the second input gear are both provided with weight-reducing grooves and / or reinforcing ribs.

[0021] Preferably, in the above-described variable speed transmission system, at least one of the first output gear, the first input gear, the second output gear, and the second input gear is a spiral gear;

[0022] or,

[0023] At least one of the first output gear, the first input gear, the second output gear, and the second input gear is a spur gear.

[0024] Preferably, in the above-described variable speed transmission system, the first clutch is a wet friction clutch; and / or,

[0025] The second clutch is an overrunning clutch.

[0026] Preferably, the variable speed transmission system further includes a speed reduction device connected to the output end of the first output shaft, used to reduce the speed output by the first output shaft.

[0027] Preferably, in the above-mentioned variable speed transmission system, the reduction device includes a first driving bevel gear, a first driven bevel gear, a transmission shaft, a second driving bevel gear, and a second driven bevel gear;

[0028] The first driving bevel gear is connected to the output end of the first output shaft.

[0029] The first driven bevel gear is disposed in the middle of the transmission shaft, and the first driven bevel gear meshes with the first driving bevel gear.

[0030] The drive shaft is provided with the second driving bevel gear at both ends and meshes with the second driven bevel gear, which is located on the target shaft.

[0031] A cross-rotor helicopter includes cross-rotors and a variable speed transmission system, wherein the rotor shafts of the cross-rotors are connected to the variable speed transmission system.

[0032] The variable speed transmission system is the variable speed transmission system described in any of the above schemes.

[0033] The variable speed transmission system provided in this application includes a first input shaft, a first clutch, and a first output shaft. The first input shaft is connected to the first output shaft via the first clutch. It also includes a speed-changing device, at least one of which comprises a first gear train mechanism, a second gear train mechanism, and a second clutch. The first gear train mechanism is connected to the second gear train mechanism via the second clutch. The input end of the first gear train mechanism is connected to the first input shaft, and the output end of the second gear train mechanism is connected to the first output shaft. At least one of the first and second gear train mechanisms is a reduction mechanism. By engaging or disengaging the first and second clutches, the path of the output power from the first input shaft is changed. The output power from the first input shaft travels through different paths, resulting in different speeds output by the first output shaft. The variable speed transmission system disclosed in this application can output at least two speeds. High-speed helicopters using the variable speed transmission system disclosed in this application achieve the goal of reducing rotor speed, thereby reducing the impact of shock waves from the advancing blades.

[0034] An embodiment of this application also provides a cross-rotor helicopter, including cross-rotors and a variable speed transmission system. The rotor shafts of the cross-rotors are connected to the variable speed transmission system, which is the variable speed transmission system described in any of the above embodiments. Since the variable speed transmission system has the aforementioned technical effects, helicopters with this variable speed transmission system also have the same technical effects, and will not be described further here. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort, and this application can be applied to other similar scenarios based on the provided drawings. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0036] Figure 1 This is a perspective view of the variable speed transmission system according to an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the structure of the variable speed transmission system according to an embodiment of this application;

[0038] Figure 3 This is a schematic diagram of the high-speed output of the variable speed transmission system according to an embodiment of this application;

[0039] Figure 4 This is a schematic diagram of the low-speed output of the variable speed transmission system according to an embodiment of this application.

[0040] The attached diagram is described below:

[0041] 11-First input shaft; 12-First clutch; 13-First output shaft; 14-First input gear; 15-First output gear; 16-Second output shaft; 17-Second clutch; 18-Second input shaft; 19-Second input gear; 110-Second output gear;

[0042] 2-Reduction gear; 21-First driving bevel gear; 22-First driven bevel gear; 23-Transmission shaft; 24-Second driving bevel gear; 25-Second driven bevel gear; 26-Target shaft. Detailed Implementation

[0043] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant application and not intended to limit the application. The described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of the present application.

[0044] It should be noted that, for ease of description, only the parts relevant to the application are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined, provided that the combined technical features are not contradictory. All feasible combinations of features are the technical content explicitly described herein. Any one of the multiple sub-features contained in the same statement can be applied independently, without necessarily being applied together with other sub-features.

[0045] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0046] In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more.

[0047] Firstly, the embodiments of this application disclose a variable speed transmission system capable of outputting at least two speeds, the magnitude of which is designed by those skilled in the art according to actual needs.

[0048] like Figure 1 As shown, the variable speed transmission system includes a first input shaft 11, a first clutch 12 and a first output shaft 13. The first input shaft 11 is connected to the first output shaft 13 through the first clutch 12.

[0049] The variable speed transmission system also includes a speed change device, and the number of speed change devices is at least one. The speed change device includes a first gear train mechanism, a second gear train mechanism, and a second clutch 17. The first gear train mechanism is connected to the second gear train mechanism through the second clutch 17.

[0050] The input end of the first gear train mechanism is connected to the first input shaft 11, and the output end of the second gear train mechanism is connected to the first output shaft 13. At least one of the first gear train mechanism and the second gear train mechanism is a speed reduction mechanism.

[0051] When the rotational speed of the first input shaft 11 is less than the preset rotational speed, the first clutch 12 engages and the second clutch 17 disengages; when the rotational speed of the first input shaft 11 is equal to or greater than the preset rotational speed, the first clutch 12 disengages and the second clutch 17 engages.

[0052] By engaging or disengaging the first clutch 12 and the second clutch 17, the path of the output power of the first input shaft 11 is changed. After the output power of the first input shaft 11 passes through different paths, the speed output by the first output shaft 13 is different. The variable speed transmission system disclosed in this application embodiment can output at least two speeds.

[0053] The first clutch 12 engages, and all the second clutches 17 disengage. The first input shaft 11, the first clutch 12, and the first output shaft 13 cooperate to output a first speed. When the first clutch 12 disengages, one of the second clutches 17 engages, and the other second clutches 17 disengage. The output power of the first input shaft 11 passes through the first gear train mechanism, the engaged second clutches 17, and the second gear train mechanism, and is then output through the first output shaft 13 to output a second speed. In this application, at least one of the first gear train mechanism and the second gear train mechanism is a reduction mechanism, and the speed of the second speed is lower than the speed of the first speed.

[0054] The input end of the first input shaft 11 is connected to a power source, which drives the first input shaft 11 to rotate. The power source is generally an engine, but hybrid power systems or other devices capable of providing power are also possible.

[0055] Optionally, the output end of the power source is connected to the flange of the first input shaft 11 via a coupling, the first input shaft 11 is connected to the first clutch 12 via a flange, and the first clutch 12 is connected via a splined first output shaft 13.

[0056] Taking a variable speed transmission system applied to a cross-rotor helicopter as an example, the output end of the first output shaft 13 of the variable speed transmission system is connected to the rotor shaft of the cross-rotor helicopter. During normal operation, the first clutch 12 is engaged, all second clutches 17 are disengaged, and the first input shaft 11 is connected to the first output shaft 13 via the first clutch 12, causing the rotor to rotate at high speed. When the rotor generates a shock wave due to excessive speed, the first clutch 12 disengages, one of the second clutches 17 engages, and the others disengage. The first input shaft 11, through the first gear train mechanism, the engaged second clutches 17, and the second gear train mechanism, is then connected to the first output shaft 13, outputting a low speed to reduce the rotor's rotational speed. The cross-rotor helicopter employing the variable speed transmission system disclosed in this application achieves the goal of reducing rotor speed through the variable speed transmission system, thereby reducing the impact of shock waves from the advancing blades and making high-speed flight possible.

[0057] In an embodiment where there is one transmission device, such as Figure 1 As shown, the rotor speed can be reduced to the required speed in one step;

[0058] In embodiments where there are at least two speed-changing devices (not shown in the figure), the rotor can be reduced to the required speed step by step, or reduced to the required speed in one step.

[0059] like Figure 1-4 The diagram shown is a structural schematic of a variable speed transmission system including a speed change device. Figure 3 As shown, the first clutch 12 is engaged, the second clutch 17 is disengaged, and the power of the first input shaft 11 is directly transmitted to the first output shaft 13 through the first clutch 12, resulting in the first output shaft 13 outputting high speed; as... Figure 4 As shown, the first clutch 12 is disengaged and the second clutch 17 is engaged. The power of the first input shaft 11 is transmitted to the first output shaft 13 through the transmission device, and the first output shaft 13 outputs a low speed.

[0060] The variable speed transmission system disclosed in this application transmits power to a first output shaft 13 or a speed change device through a first input shaft 11, and the speed of the first input shaft 11 or the speed change device is output through a first output shaft 13. The variable speed transmission system has a first input shaft 11 and a first output shaft 13, which has a simple structure, reduces the number of parts used, reduces manufacturing costs, and has a compact structure.

[0061] In some embodiments, such as Figure 1 and Figure 2 As shown, the first gear train mechanism includes a first input gear 14, a first output gear 15, and a second output shaft 16.

[0062] The first input gear 14 is located at the input end of the first input shaft 11.

[0063] The first output gear 15 is installed at the input end of the second output shaft 16. The output end of the second output shaft 16 is connected to the second clutch 17. The first output gear 15 meshes with the first input gear 14. The number of teeth of the first output gear 15 is greater than the number of teeth of the first input gear 14, thereby achieving speed reduction and ultimately converting the high speed and low torque of the power source into low speed and high torque.

[0064] During operation, the first clutch 12 disengages and the second clutch 17 engages. The first input shaft 11 drives the first input gear 14 to rotate. The first input gear 14 meshes with the first output gear 15, driving the second output shaft 16 to rotate. The second output shaft 16 transmits power to the second gear train mechanism through the second clutch 17, and the second gear train mechanism transmits power to the first output shaft 13.

[0065] In embodiments where the first gear train mechanism is a reduction gear mechanism, the second gear train mechanism can be either a constant velocity transmission mechanism or a reduction gear mechanism.

[0066] In the embodiment where the first gear train mechanism is a constant velocity transmission mechanism, the number of teeth of the first output gear 15 is equal to the number of teeth of the first input gear 14, and the second gear train mechanism is a reduction mechanism.

[0067] In some embodiments, the second gear train mechanism includes a second input gear 19, a second output gear 110, and a second input shaft 18; the input end of the second input shaft 18 is connected to the second clutch 17, and the output end of the second input shaft 18 is provided with the second input gear 19.

[0068] The second output gear 110 is disposed on the first output shaft 13, and the second output gear 110 meshes with the second input gear 19.

[0069] During operation, the first clutch 12 disengages, and the second clutch 17 engages. The output end of the power source is connected to the flange of the first input shaft 11 via a coupling. The first input shaft 11 is splined to the first input gear 14, which meshes with the first output gear 15. The first output gear 15 is splined to the second output shaft 16, which is splined to the second clutch 17. The second clutch 17 is flanged to the second input shaft 18, which is splined to the second input gear 19. The second input gear 19 meshes with the second output gear 110, which is splined to the first output shaft 13. The power source drives the first input gear 14, the first output gear 15, the second output shaft 16, the second clutch 17, the second input shaft 18, the second input gear 19, and the second output gear 110 via the first input shaft 11. The second output gear 110 drives the first output shaft 13 to rotate, outputting a low speed.

[0070] The first input shaft 11, the second output shaft 16, the second input shaft 18, and the first output shaft 13 serve as transmission shafts, cooperating with the first output gear 15, the first input gear 14, the second input gear 19, and the second output gear 110 to transmit a determined torque and speed. The first input shaft 11, the second output shaft 16, the second input shaft 18, and the first output shaft 13 are all supported by bearings.

[0071] The first input shaft 11, the second output shaft 16, the second input shaft 18, and the first output shaft 13 are all hollow shafts, which minimize weight and meet system reliability requirements, making it convenient to control the weight balance of the helicopter.

[0072] At least one of the following: the first input shaft 11 and the first input gear 14, the second output shaft 16 and the first output gear 15, the second input shaft 18 and the second input gear 19, and the first output shaft 13 and the second output gear 110, adopts a spline fit, which reduces assembly complexity, facilitates assembly, and ensures high reliability.

[0073] In an embodiment where the second gear train mechanism is a constant velocity transmission mechanism, the number of teeth on the second output gear 110 is equal to the number of teeth on the second input gear 19, and the first gear train mechanism is a reduction mechanism.

[0074] In the embodiment where the second gear train mechanism is a reduction mechanism, the number of teeth of the second output gear 110 is greater than the number of teeth of the second input gear 19, thereby achieving speed reduction and ultimately converting the high speed and low torque of the power source into low speed and high torque.

[0075] In embodiments where both the first and second gear train mechanisms are reduction mechanisms, the variable speed transmission system can perform two-stage reduction. In this embodiment, the transmission ratio between the first output gear 15 and the first input gear 14 and the transmission ratio between the second input gear 19 and the second output gear 110 can be the same or different, and different speeds can be obtained by combining the same or different transmission ratios.

[0076] Optionally, the first input shaft 11 is parallel to the second output shaft 16, and the second input shaft 18 is parallel to the first output shaft 13; the first output gear 15, the first input gear 14, the second input gear 19, and the second output gear 110 are all external gears. The end faces of the first output gear 15 and the first input gear 14 are located on the same plane and their axes are parallel to each other. This spatial layout is to have two output points on the gear set formed by the first output gear 15 and the first input gear 14; the second input gear 19 and the second output gear 110 adopt the same layout as the first output gear 15 and the first input gear 14.

[0077] Optionally, the first input gear 14 and the second input gear 19 have the same specifications, and the first output gear 15 and the second output gear 110 have the same specifications. Same specifications mean that the first input gear 14 and the second input gear 19, as well as the first output gear 15 and the second output gear 110, have the same manufacturing parameters and structural shape, such as the number of teeth, module, pitch circle diameter, etc., and also have the same degree of material reduction, keyways, etc.

[0078] The second output gear 110 has a similar number of teeth to the second input gear 19.

[0079] The hubs of the first output gear 15 and the first input gear 14 are provided with weight-reducing grooves and reinforcing ribs, and / or the hubs of the second output gear 110 and the second input gear 19 are provided with weight-reducing grooves and / or reinforcing ribs, which enables the helicopter to maintain the lightest weight while meeting reliability requirements.

[0080] At least one of the first output gear 15, the first input gear 14, the second output gear 110, and the second input gear 19 is a spiral gear. Spiral gears have advantages such as good chemical and corrosion resistance, noise reduction and vibration damping, long service life, high load-bearing capacity, light weight, and low cost.

[0081] Optionally, the first output gear 15, the first input gear 14, the second output gear 110, and the second input gear 19 can also be spur gears.

[0082] In embodiments where there is one transmission device, such as Figure 1 As shown, the second output shaft 16 and the first input shaft 11 are arranged along the axial direction of the transmission shaft 23.

[0083] In embodiments where there are at least two transmission devices, the second output shafts 16 of the at least two transmission devices are evenly distributed circumferentially along the first input shaft 11.

[0084] In some embodiments, the first clutch 12 is a wet friction clutch. A wet friction clutch is a friction clutch in which all friction components are immersed in oil, and it is often a multi-disc type. When a wet friction clutch is disengaged, the friction plates slip against each other due to the presence of oil pressure. When a wet friction clutch is engaged, the oil between the plates is squeezed out by the applied pressure, resulting in a tight engagement and torque transmission. It has advantages such as low wear, good heat dissipation, low temperature rise, and long service life, and is suitable for transmitting large torques.

[0085] The first clutch 12 is not limited to a wet friction clutch, but can also be other clutches.

[0086] The second clutch 17 is an overrunning clutch. An overrunning clutch is a device that has a self-engaging function by utilizing changes in the speed or rotation direction of the driving and driven parts. The overrunning clutch in this design can be any one of a wedge-type overrunning clutch, a ball-type overrunning clutch, or a ratchet-type overrunning clutch.

[0087] In some embodiments, the variable speed transmission system disclosed in this application further includes a speed reduction device 2 connected to the output end of the first output shaft 13, for reducing the speed of the first output shaft 13.

[0088] In application, the power source first transmits power to the first input shaft 11. After passing through the first clutch 12 or the first reduction mechanism, the power then passes through the second reduction mechanism, which ultimately converts the single state of high speed and low torque of the power source into two states of low speed and high torque.

[0089] like Figure 2 As shown, the reduction gear 2 includes a first driving bevel gear 21, a first driven bevel gear 22, a transmission shaft 23, a second driving bevel gear 24, and a second driven bevel gear 25.

[0090] The first driving bevel gear 21 is connected to the output end of the first output shaft 13. A first driven bevel gear 22 is provided in the middle of the transmission shaft 23, and the first driven bevel gear 22 meshes with the first driving bevel gear 21. Second driving bevel gears 24 are provided at both ends of the transmission shaft 23, and mesh with second driven bevel gears 25. The second driven bevel gears 25 are located on the target shaft 26. When the variable speed transmission system is used in a helicopter, the target shaft 26 is the rotor shaft.

[0091] The first output shaft 13 rotates, driving the first driving bevel gear 21 to rotate. The first driven bevel gear 22 meshes with the first driving bevel gear 21, driving the first driven bevel gear 22 to rotate. The first driven bevel gear 22 drives the transmission shaft 23 to rotate. The transmission shaft 23 drives the second driving bevel gear 24 located at both ends of it to rotate. The second driving bevel gear 24 meshes with the second driven bevel gear 25, driving the target shaft 26 to rotate.

[0092] The power source transmits power to the two rotors of the helicopter via the target shafts 26 on both sides, thereby achieving the goal of synchronously driving the two rotors with one power source and simultaneously achieving variable speed rotation of the two rotors.

[0093] The variable speed transmission system disclosed in this solution can realize the synchronous driving of two rotors through a single power source by using a clutch-configured speed change device and two bevel gear sets (the second driving bevel gear 24 and the second driven bevel gear 25 form a bevel gear set, and the first driven bevel gear 22 and the first driving bevel gear 21 form a bevel gear set). This achieves variable speed rotation of the rotors by using fewer parts, with a simple structure, reducing manufacturing costs. Moreover, the structure is compact and has high transmission efficiency, which is beneficial to improving the performance of the helicopter.

[0094] Secondly, embodiments of this application also provide a cross-rotor helicopter, including cross-rotors and a variable speed transmission system, wherein the rotor shaft of the cross-rotors is connected to the variable speed transmission system, and the variable speed transmission system is the variable speed transmission system described in any of the above embodiments.

[0095] Since the variable speed transmission system has the above-mentioned technical effects, helicopters with this variable speed transmission system also have the same technical effects, which will not be elaborated here.

[0096] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed, and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. The scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A variable speed transmission system, characterized in that, It includes a first input shaft (11), a first clutch (12) and a first output shaft (13), wherein the first input shaft (11) is connected to the first output shaft (13) through the first clutch (12); It also includes a transmission device, at least one of which includes a first gear train mechanism, a second gear train mechanism, and a second clutch (17). The first gear train mechanism is connected to the second gear train mechanism via the second clutch (17). The first gear train mechanism is connected to the first input shaft (11), and the second gear train mechanism is connected to the first output shaft (13). At least one of the first gear train mechanism and the second gear train mechanism is a speed reduction mechanism to reduce the output speed of the first output shaft (13). The rotational speed of the first input shaft (11) is less than the preset rotational speed, the first clutch (12) engages, and the second clutch (17) disengages; The rotational speed of the first input shaft (11) is equal to or greater than the preset rotational speed, the first clutch (12) disengages, and the second clutch (17) engages.

2. The variable speed transmission system according to claim 1, characterized in that, The first gear train mechanism includes a first input gear (14), a first output gear (15), and a second output shaft (16). The first input gear (14) is disposed at the input end of the first input shaft (11), the first output gear (15) is installed at the input end of the second output shaft (16), the output end of the second output shaft (16) is connected to the second clutch (17), the first output gear (15) meshes with the first input gear (14), and the number of teeth of the first output gear (15) is greater than or equal to the number of teeth of the first input gear (14); And / or, The second gear train mechanism includes a second input gear (19), a second output gear (110), and a second input shaft (18). The input end of the second input shaft (18) is connected to the second clutch (17). The output end of the second input shaft (18) is provided with the second input gear (19). The second output gear (110) is provided on the first output shaft (13). The second output gear (110) meshes with the second input gear (19). The number of teeth of the second output gear (110) is greater than or equal to the number of teeth of the second input gear (19).

3. The variable speed transmission system according to claim 2, characterized in that, The transmission ratio between the first output gear (15) and the first input gear (14) is the same as or different from the transmission ratio between the second output gear (110) and the second input gear (19).

4. The variable speed transmission system according to claim 2, characterized in that, At least one of the first input shaft (11), the second input shaft (18), the first output shaft (13), and the second output shaft (16) is a hollow shaft.

5. The variable speed transmission system according to claim 2, characterized in that, The hubs of the first output gear (15) and the first input gear (14) are both provided with weight-reducing grooves and / or reinforcing ribs. And / or, The hubs of the second output gear (110) and the second input gear (19) are provided with weight-reducing grooves and / or reinforcing ribs.

6. The variable speed transmission system according to claim 2, characterized in that, At least one of the first output gear (15), the first input gear (14), the second output gear (110), and the second input gear (19) is a spiral gear; or, At least one of the first output gear (15), the first input gear (14), the second output gear (110), and the second input gear (19) is a spur gear.

7. The variable speed transmission system according to any one of claims 1-6, characterized in that, The first clutch (12) is a wet friction clutch; and / or, The second clutch (17) is an overrunning clutch.

8. The variable speed transmission system according to any one of claims 1-6, characterized in that, It also includes a speed reduction device (2), which is connected to the output end of the first output shaft (13) to reduce the speed output by the first output shaft (13).

9. The variable speed transmission system according to claim 8, characterized in that, The speed reduction device (2) includes a first driving bevel gear (21), a first driven bevel gear (22), a transmission shaft (23), a second driving bevel gear (24), and a second driven bevel gear (25); The first driving bevel gear (21) is connected to the output end of the first output shaft (13). The first driven bevel gear (22) is disposed in the middle of the transmission shaft (23), and the first driven bevel gear (22) meshes with the first driving bevel gear (21). The two ends of the drive shaft (23) are provided with the second driving bevel gear (24) and mesh with the second driven bevel gear (25), which is located on the target shaft (26).

10. A cross-rotor helicopter, characterized in that, It includes a cross-rotor and a variable speed transmission system, wherein the rotor shaft of the cross-rotor is connected to the variable speed transmission system. The variable speed transmission system is the variable speed transmission system described in any one of claims 1-9.

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