Compound planet two-gear speed control system for aero-engine and aero-engine

Abstract

The invention relates to a compound planetary two-gear speed control system for an aero-engine and the aero-engine, a first planetary gear train and a second planetary gear train are rigidly connected to form a compound planetary gear train, and two sets of brakes are arranged to realize double-speed-ratio switching between a fan and a low-pressure rotor; the first sun gear and the second sun gear are rigidly connected through a coaxial shaft piece, the first planet carrier is rigidly connected with the second gear ring, and the system can be switched between a low-speed high-torque mode and a high-speed high-efficiency mode by selectively locking the second planet carrier or a sun gear shaft; the low-speed mode is suitable for high-thrust working conditions such as takeoff and climbing and has high transmission ratio and high torque capacity; the high-speed mode is suitable for cruising, high-speed flight and other low-resistance and high-efficiency working conditions, and fan matching performance and propulsion efficiency are improved; the system is compact in structure, clear in transmission path and simple in control logic, effectively solves the problems that in traditional design, the transmission ratio is fixed, and multi-working-condition operation cannot be adapted, and improves the overall performance of an engine and fuel economy.

Description

Technical Field

[0001] The present invention belongs to the technical field of aeroengines, and relates to a compound planetary two-speed transmission system for an aeroengine and an aeroengine. Background Art

[0002] In order to reduce fuel consumption and noise, modern aeroengines widely adopt a high bypass ratio design. Such high bypass ratio engines are usually equipped with large-diameter fans, but the tip speed of the fans is limited, and their optimal operating speed is significantly lower than the efficient operating speed range of the low-pressure rotor, resulting in an obvious speed mismatch problem between the two.

[0003] To solve this contradiction, the prior art mainly proposes two solutions: the first is the geared turbofan (GTF) technology, which decouples the speeds of the fan and the low-pressure rotor by setting a speed reducer between the low-pressure compressor and the fan. The second is the three-rotor support structure, which improves the aerodynamic matching efficiency of the entire propulsion system by introducing a middle shaft system. These technologies have alleviated the speed matching problem brought about by the high bypass ratio design to a certain extent and promoted the development of related engine technologies.

[0004] However, most of the existing GTF technologies and three-rotor structures adopt fixed transmission ratios or fixed speed designs, lacking the ability to dynamically adjust the transmission characteristics according to the requirements under different flight conditions. Due to the invariable transmission ratio, the engine often needs to make a compromise between noise control, fuel efficiency, and output performance, and it is difficult to achieve optimal performance under all conditions. In addition, the fixed transmission ratio system has poor adaptability to load changes, is prone to meshing impact and exciting system resonance, thereby increasing broadband noise and affecting the reliability and service life of the transmission system.

[0005] Therefore, there is an urgent need to propose a compound planetary two-speed transmission system for an aeroengine to meet the speed matching requirements under different flight states and improve the comprehensive performance and operation stability of the system. Summary of the Invention

[0006] In view of this, the present invention provides a compound planetary two-speed transmission system for an aeroengine and an aeroengine to solve the problems of the speed mismatch between the fan and the low-pressure rotor in the design of aeroengines, the fixed transmission ratio in the existing design, the difficulty in flexibly switching according to different flight conditions, and the limitations in use. Its structural design is compact, the transmission path is clear, it can realize the two-speed ratio switching between the fan and the low-pressure rotor, and optimize the fuel consumption and noise level of the engine.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A compound planetary two-speed transmission system for an aero-engine, comprising a compound planetary gear train formed by rigidly connecting a first planetary gear train and a second planetary gear train, a first brake, and a second brake; the first planetary gear train includes a first ring gear fixedly connected to an input shaft, a plurality of first planetary gears meshing internally with the first ring gear, a first sun gear meshing externally with the first planetary gears, and a first planetary carrier supporting the first planetary gears through a planetary gear shaft; the second planetary gear train includes a second ring gear, a plurality of second planetary gears meshing internally with the second ring gear, a second sun gear meshing externally with the second planetary gears, and a second planetary carrier supporting the second planetary gears through a planetary gear shaft; wherein, the first sun gear and the second sun gear are coaxially and rigidly connected through a sun gear shaft, and the first planetary carrier and the second ring gear are rigidly connected through a connecting member to form a compound planetary gear train.

[0009] Furthermore, the first brake is arranged between the second planetary carrier and the engine fixed housing, and is used to selectively restrict the rotation of the second planetary carrier; the second brake is arranged between the sun gear shaft and the engine fixed housing, and is used to selectively restrict the rotation of the sun gear shaft to achieve the switching function of double speed ratios. This design has a simple control logic, high switching efficiency, and high operating reliability.

[0010] Furthermore, the input end of the first ring gear is connected to the output shaft of the low-pressure turbine through a spline, and the output end of the second ring gear is connected to the drive shaft of the fan through a flange.

[0011] Furthermore, when both the first brake and the second brake are in a non-braking state, the compound planetary gear train has two degrees of freedom, the transmission system is in a power interruption state, and there is no effective torque output.

[0012] Furthermore, the combined control method of the first brake and the second brake is as follows: when the first brake locks the second planetary carrier and the second brake is released, the system is in a low-speed driving mode; when the second brake locks the sun gear shaft and the first brake is released, the system is in a high-speed driving mode. When both brakes are released, the transmission system is in a power interruption state; when both brakes are locked simultaneously, the system is in an abnormal working state of mechanical constraint conflict, and this situation is prohibited from occurring.

[0013] Furthermore, when the first brake locks the second planetary carrier and the second brake is in a non-braking state, the power transmission path of the transmission system is: input shaft → first ring gear → first planetary gear → first planetary carrier → second ring gear → second planetary gear → second sun gear → sun gear shaft → first sun gear → first planetary carrier, forming a complete torque closed-loop. The transmission ratio of the system satisfies i1 = 1 + (1 + α2) / α1, where α1 is the tooth number ratio of the first ring gear to the first sun gear, and α2 is the tooth number ratio of the second ring gear to the second sun gear, realizing the low-speed driving mode of the fan. In this mode, the transmission system has a high torque transmission capacity, is suitable for working conditions such as takeoff and cruise, and effectively improves the fuel efficiency and life of the engine.

[0014] Further, when the second brake locks the sun gear shaft and the first brake is in the non-braking state, the power transmission path of the transmission system is: input shaft → first ring gear → first planet gear → first planet carrier → second ring gear, directly driving the drive shaft of the fan. The system transmission ratio satisfies i2 = 1 + 1 / α1, where α1 is the tooth number ratio of the first ring gear to the first sun gear, realizing the high-speed driving mode of the fan. In this mode, the transmission system responds quickly, meets the high-speed flight requirements, and effectively improves the fan speed matching and propulsion efficiency.

[0015] The compound planetary two-speed transmission system for an aeroengine is applicable to a dual-rotor aeroengine. Its high-pressure rotor consists of a high-pressure compressor and a high-pressure turbine, and its low-pressure rotor consists of a low-pressure compressor and a low-pressure turbine. The compound planetary transmission system for an aeroengine is arranged between the low-pressure rotor and the fan, and is used to realize the controllable switching of the fan speed under different flight conditions.

[0016] An aeroengine includes the above-mentioned compound planetary two-speed transmission system for an aeroengine.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The compound planetary two-speed transmission system for an aeroengine disclosed by the present invention is composed of a first planetary gear train and a second planetary gear train rigidly connected to form a compound planetary gear train, and is equipped with two sets of brakes. Through the compound planetary gear train and the two brakes, the efficient switching of double speed ratios is realized, and the fan speed can be flexibly adjusted according to the speed requirements of the aeroengine fan under different conditions such as takeoff, cruise, and high-speed flight, improving the overall performance and fuel economy of the engine. This design avoids the use of clutches in traditional transmission systems, reduces mechanical wear and control complexity, and enhances the stability and safety of the transmission system.

[0019] 2. The compound planetary two-speed transmission system for an aeroengine disclosed by the present invention adopts the form of two planetary gear trains compounded by rigid connection to construct a compact and reasonable compound planetary gear train structure. Compared with the traditional multi-stage gear superposition or series structure, the overall transmission layout is more compact, the axial dimension is significantly shortened, the number of components is reduced, the system weight and volume are reduced, meeting the strict design requirements of aeroengines for lightweight and compactness. At the same time, this compound structure improves the transmission efficiency and torque transmission capacity of the transmission system.

[0020] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. Brief Description of the Drawings

[0021] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings. The details are as follows:

[0022] Figure 1 It is a schematic diagram of the cooperation between the compound planetary two-speed transmission system for an aero-engine of the present invention and the engine system;

[0023] Figure 2 It is the transmission principle diagram of the compound planetary two-speed transmission system for an aero-engine of the present invention;

[0024] Figure 3 It is the low-speed gear power transmission path diagram of the compound planetary two-speed transmission system for an aero-engine of the present invention;

[0025] Figure 4 It is the high-speed gear power transmission path diagram of the compound planetary two-speed transmission system for an aero-engine of the present invention.

[0026] Reference numerals: input shaft 1, first sun gear 2, first planet gear 3, first ring gear 4, first planet carrier 5, second ring gear 6, second planet gear 7, second sun gear 8, second planet carrier 9, sun gear shaft 10, first brake 11, second brake 12, low-pressure turbine 13, high-pressure turbine 14, high-pressure compressor 15, low-pressure compressor 16, fan 17. Detailed Embodiments

[0027] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] As Figure 1 and Figure 2 shown, a compound planetary two-speed transmission system for an aero-engine provided by the present invention is applicable to a dual-rotor aero-engine. Its high-pressure rotor consists of a high-pressure compressor 16 and a high-pressure turbine 14, and its low-pressure rotor consists of a low-pressure compressor 15 and a low-pressure turbine 13. This compound planetary transmission system is arranged between the low-pressure rotor and the fan 17 and is used to achieve controllable switching of the fan speed under different flight conditions.

[0029] Specifically, the compound planetary transmission system includes a compound planetary gear train, a first brake 11, and a second brake 12. The compound planetary gear train is composed of a first planetary gear train and a second planetary gear train through a rigid connection.

[0030] The first planetary gear train includes a first ring gear 4 fixedly connected to the input shaft 1. A plurality of first planet gears 3 are internally meshed with the first ring gear 4, and the first planet gears 3 are externally meshed with a first sun gear 2. All the first planet gears 3 are mounted on a first planet carrier 5 through planet gear shafts. The input end of the first ring gear 4 is connected to the output shaft of the low-pressure turbine 13 through a spline to achieve low-pressure power input.

[0031] The second planetary gear train includes a second ring gear 6. A plurality of second planet gears 7 are internally meshed with the second ring gear 6, and the second planet gears 7 are externally meshed with a second sun gear 8. The plurality of second planet gears 7 are also mounted on a second planet carrier 9 through planet gear shafts. The second ring gear 6 is connected to the drive shaft of the fan 17 through a flange to achieve variable-speed output.

[0032] The first sun gear 2 and the second sun gear 8 are rigidly connected through a hollow sun gear shaft 10 to achieve coaxial rotation. The first planet carrier 5 is rigidly connected to the second ring gear 6 through a connecting member to ensure that a stable torque transmission path is formed structurally between the two planetary gear trains.

[0033] A first brake 11 is arranged between the second planet carrier 9 and the fixed housing and is used to selectively lock the rotation of the second planet carrier 9; a second brake 12 is arranged between the sun gear shaft 10 and the fixed housing and is used to selectively lock the rotation of the sun gear shaft 10. The control logics of the two brakes are clear, constituting clear gear shifting conditions:

[0034] As Figure 3 Shown is the power transmission path diagram for the low-speed gear: When the first brake 11 locks the second planet carrier 9 and the second brake 12 is released, the power is transmitted from the input shaft 1 in sequence to the first ring gear 4 → the first planet gear 3 → the first planet carrier 5 → the second ring gear 6 → the second planet gear 7 → the second sun gear 8 → the sun gear shaft 10 → the first sun gear 2, and finally returns to the first planet carrier 5, forming a complete closed-loop transmission path to achieve a larger transmission ratio i1 = 1 + (1 + α2) / α1, where α1 is the tooth number ratio of the first ring gear to the first sun gear, and α2 is the tooth number ratio of the second ring gear to the second sun gear. Taking α1 = 2 and α2 = 3 as an example, it is calculated that i1 = 3. This working condition is suitable for low-speed and high-thrust requirements such as takeoff and climb, and has good torque capacity and efficiency.

[0035] As Figure 4 Shown is the power transmission path diagram for the high-speed gear: When the second brake 12 locks the sun gear shaft 10 and the first brake 11 is released, the power path is the input shaft 1 → the first ring gear 4 → the first planet gear 3 → the first planet carrier 5 → the second ring gear 6, and the fan drive shaft is directly driven by the second ring gear 6 to achieve a smaller transmission ratio i2 = 1 + 1 / α1. Taking α1 = 2 as an example, i2 = 1.5 can be obtained. This mode is suitable for working conditions such as cruising and high-speed flight. The fan speed is higher and the efficiency is better.

[0036] When both brakes are released, the compound planetary gear train has two degrees of freedom, and the system is in an unloaded state without effective torque output, which is suitable for auxiliary working conditions such as starting and lubricating oil preheating. When both brakes are locked simultaneously, a mechanical constraint conflict occurs in the system, and no effective degree of freedom can be formed inside the transmission, so this state cannot be used as a normal working condition.

[0037] Compared with the traditional single-speed structure, the compound planetary two-speed transmission system of the present invention can provide optimized fan speed control ability under different flight conditions, achieve two-speed ratio transmission through a compact compound planetary arrangement, and can significantly improve the adaptability, energy-saving performance and noise control ability of the engine, having good engineering practical value and development potential.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A compound planetary two-speed transmission system for an aeroengine, characterized in that The first planetary gear train includes a first ring gear (4) fixedly connected to the input shaft (1), a plurality of first planet gears (3) meshing internally with the first ring gear (4), a first sun gear (2) meshing externally with the first planet gears (3), and a first planet carrier (5) supporting the first planet gears (3) through planet gear shafts; the second planetary gear train includes a second ring gear (6), a plurality of second planet gears (7) meshing internally with the second ring gear (6), a second sun gear (8) meshing externally with the second planet gears (7), and a second planet carrier (9) supporting the second planet gears (7) through planet gear shafts; wherein, the first sun gear (2) and the second sun gear (8) are coaxially and rigidly connected through a sun gear shaft (10), the first planet carrier (5) and the second ring gear (6) are rigidly connected through a connecting member, the first planetary gear train and the second planetary gear train are rigidly connected to form a compound planetary gear train, and two sets of brakes are correspondingly equipped.

2. The compound planetary two-speed transmission system according to claim 1, characterized in that, A first brake (11) is provided between the second planet carrier (9) and the engine fixed housing, and the first brake (11) is used to selectively lock the rotation of the second planet carrier (9); a second brake (12) is provided between the sun gear shaft (10) and the engine fixed housing, and the second brake (12) is used to selectively lock the rotation of the sun gear shaft (10).

3. The compound planetary two-speed transmission system according to claim 2, wherein A low-pressure turbine (13) is fixedly connected to the input end of the first ring gear (4), and a fan (17) is fixedly connected to the output end of the second ring gear (6).

4. The compound planetary two-speed transmission system according to claim 2, wherein When both the first brake (11) and the second brake (12) are in a non-braking state, the compound planetary gear train has two degrees of freedom, the transmission system is in a power interruption state, and there is no effective torque output.

5. The compound planetary two-speed transmission system according to claim 3, characterized in that, The combined control mode of the first brake (11) and the second brake (12) is as follows: when the first brake (11) locks the second planet carrier (9) and the second brake (12) is released, the system is in a low-speed driving mode; when the second brake (12) locks the sun gear shaft (10) and the first brake (11) is released, the system is in a high-speed driving mode.

6. The compound planetary two-speed transmission system according to claim 5, characterized in that When the first brake (11) locks the second planet carrier (9) and the second brake (12) is in a non-braking state, its power transmission path is: input shaft (1) → first ring gear (4) → first planet gear (3) → first planet carrier (5) → second ring gear (6) → second planet gear (7) → second sun gear (8) → sun gear shaft (10) → first sun gear (2) → first planet carrier (5), forming a complete torque closed loop, and the system transmission ratio satisfies i1 = 1 + (1 + α2) / α1, where α1 is the tooth number ratio of the first ring gear (4) to the first sun gear (2), and α2 is the tooth number ratio of the second ring gear (6) to the second sun gear (8), realizing the low-speed driving mode of the fan (17).

7. The compound planetary two-speed transmission system according to claim 4, characterized in that, When the second brake (12) locks the sun gear shaft (10) and the first brake (11) is in a non-braking state, the power transmission path is: input shaft (1) → first ring gear (4) → first planet gear (3) → first planet carrier (5) → second ring gear (6), directly driving the drive shaft of the fan (17). The system transmission ratio satisfies i2 = 1 + 1 / α1, where α1 is the tooth number ratio of the first ring gear (4) to the first sun gear (2), realizing the high-speed driving mode of the fan (17).

8. The compound planetary two-speed transmission system according to any one of claims 5 to 7, characterized in that It is applicable to a dual-rotor aeroengine, the high-pressure rotor of which consists of a high-pressure compressor (16) and a high-pressure turbine (14), and the low-pressure rotor consists of a low-pressure compressor (15) and a low-pressure turbine (13). This speed change system is arranged between the low-pressure rotor and the fan (17) and is used to realize the controllable switching of the fan speed under different flight conditions.

9. An aeroengine, characterized in that, It includes the compound planetary two-speed transmission system for aeroengines described in claim 8.

Images