A tandem shaft turbofan engine with planetary reduction gear

Abstract

The application belongs to the technical field of aero-engines, and provides a series connection shaft system turbofan engine with a planetary reducer, which comprises a shaft, a fan rotor and an impeller, the shaft comprises a fan shaft, a main shaft and a reducer, the fan shaft and the main shaft are connected through the reducer, the fan rotor is fixed on the fan shaft, and the impeller is fixed on the main shaft. The application can break the rotational speed coupling relationship between the fan and the impeller, eliminate the over-constraint of the shaft system, and improve the design, processing and working performance of the engine shaft system.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine technology and provides a tandem shaft turbofan engine with a planetary reducer. Background Technology

[0002] As a core component of aviation power, the turbofan engine, especially the single-shaft turbofan engine, is widely used in the field of small aviation power due to its relatively simple structure. The core shaft system of existing conventional single-shaft turbofan engines is an integrated main shaft structure. This main shaft is a single, integral shaft, with the fan rotor, compressor impeller, and turbine rotor sequentially fixed along the axial direction. The fan rotor, impeller, and turbine rotor rotate synchronously and at the same speed with the integrated main shaft.

[0003] While the existing single-shaft turbofan engine structural design can achieve basic power transmission and air compression functions, it has revealed many insurmountable technical defects in actual engineering applications and design and development. These defects are interconnected and severely restrict the engine's design optimization, manufacturing assembly, and performance improvement, as detailed below: The coupling of fan and impeller speeds significantly increases the difficulty of fan design: Due to the structural limitations of the integrated main shaft, the fan rotor and compressor impeller must rotate synchronously and at the same speed as the main shaft. To achieve efficient air compression, the compressor impeller needs to operate at high speeds, which forces the fan rotor to maintain the same high speed. However, the fan rotor blades are large and have a high aspect ratio. At high speeds, the centrifugal force on the blades increases dramatically. This not only places extremely high demands on the material strength and structural design of the fan blades, significantly increasing the difficulty of strength design, but also easily leads to a decrease in fan aerodynamic efficiency at high speeds. It is difficult to achieve the optimal aerodynamic design solution for the fan, and it is impossible to increase the fan's airflow and pressure ratio by increasing the fan blade size or optimizing the blade aerodynamic shape, thus limiting the improvement of the engine's overall thrust and efficiency.

[0004] The shaft system has low integration and poor flexibility in transmission and layout: The integrated main shaft integrates the transmission functions of the fan, impeller and turbine into a single shaft. There is no independent speed adjustment and transmission adaptation structure. It is impossible to separate the speed adjustment according to the different working requirements of the fan and impeller. The transmission matching flexibility of the shaft system is extremely low. At the same time, the single integrated shaft structure also makes the overall layout of the engine limited by the shaft system direction. It is difficult to modularize and optimize the core components of the engine, which is not conducive to the miniaturization and integration design of the engine structure. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a tandem shaft turbofan engine with a planetary reducer, which can break the speed coupling relationship between the fan and the impeller, eliminate shaft over-constraint, and improve the design, machining, and working performance of the engine shaft system.

[0006] The technical solution of the present invention includes a shaft, a fan rotor, and an impeller. The shaft includes a fan shaft, a main shaft, and a reducer. The fan shaft and the main shaft are connected by the reducer. The fan rotor is fixed on the fan shaft, and the impeller is fixed on the main shaft.

[0007] Furthermore, the reducer is a planetary gear reducer, which includes a sun gear, planet gears, a planet carrier, and an internal gear ring. The sun gear is integrated with the shaft head of the main shaft. The planet carrier is fixedly connected to the end of the fan shaft. The planet gears are rotatably mounted on the planet carrier and mesh with the sun gear. The planet gears mesh with the internal gear ring.

[0008] Furthermore, the reduction ratio of the planetary gear reducer is adjusted by adjusting the ratio of the number of teeth on the sun gear and the planet gears, and the adjustment range of the reduction ratio is from 2:1 to 5:1.

[0009] Furthermore, the sun gear is integrated with the front end of the main shaft, the impeller is fixed in the middle of the main shaft, and a turbine rotor is fixed at the rear end of the main shaft; the turbine rotor is axially locked to the rear end of the main shaft by a turbine nut.

[0010] Furthermore, the fan shaft and main shaft adopt a double-support simple support structure, and fan bearings and main bearings are respectively configured at both ends of the axial direction of the fan shaft and the main shaft.

[0011] Furthermore, a circumferential anti-rotation structure is provided between the fan rotor and the fan shaft, and between the impeller and the main shaft. The fan rotor is axially locked and fixed to the fan shaft by a locking nut, and the impeller is axially locked and fixed to the main shaft by a locking nut.

[0012] Furthermore, the circumferential anti-rotation structure is a flat key structure or a spline structure.

[0013] Furthermore, the fan shaft and the main shaft are aligned with the same axis, and the reducer is positioned between the mating ends of the fan shaft and the main shaft to achieve torque transmission and speed regulation between the fan shaft and the main shaft.

[0014] The technical solution provided by this invention has the following advantages compared with the prior art: When this engine is working, the main shaft rotates and transmits torque to the fan shaft through a reducer, realizing the series transmission of power from the main shaft to the fan shaft. At the same time, the reducer can adjust the speed of the fan shaft and the main shaft, so that the fan rotor fixed on the fan shaft and the impeller fixed on the main shaft can rotate independently at different speeds. This structure breaks the speed coupling limitation between the fan rotor and the impeller, and can match their optimal operating speeds separately, greatly reducing the design difficulty of the fan rotor. At the same time, splitting the main shaft into independent fan shaft and main shaft simplifies the support design requirements of the shaft system, avoids the over-constraint problem caused by a single-piece main shaft, improves the flexibility and working stability of the shaft system transmission, and thus optimizes the overall design and working performance of the engine.

[0015] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the airflow direction of the present invention.

[0019] Figure label: 1. Fan shaft; 2. Main shaft; 3. Reducer; 4. Fan rotor; 5. Impeller; 6. Sun gear; 7. Planetary gear; 8. Turbine rotor; 9. Turbine nut; 10. Fan bearing; 11. Main bearing. Detailed Implementation

[0020] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of the embodiments of the present invention, unless otherwise stated, "a plurality of" means two or more.

[0023] like Figure 1 As shown, the present invention provides a tandem shaft turbofan engine with a planetary reducer 3, including a shaft body, a fan rotor 4 and an impeller 5. The shaft body includes a fan shaft 1, a main shaft 2 and a reducer 3; the fan shaft 1 and the main shaft 2 are connected by the reducer 3; the fan rotor 4 is fixed on the fan shaft 1 and the impeller 5 is fixed on the main shaft 2.

[0024] The shaft system of this turbofan engine is divided into two independent components: a fan shaft 1 and a main shaft 2, which are mechanically connected by a reducer 3. The fan rotor 4 is fixed to the fan shaft 1, and the impeller 5 is fixed to the main shaft 2. During operation, the main shaft 2 transmits torque to the fan shaft 1 via the reducer 3, achieving series power transmission. Simultaneously, the reducer 3 can adjust the speeds of the fan shaft 1 and the main shaft 2, allowing the fan rotor 4 and impeller 5 to rotate independently at different speeds. The fan shaft 1 and the main shaft 2 have collinear axes, and the reducer 3 is positioned between their mating ends, precisely fulfilling the core functions of torque transmission and speed regulation. This design breaks the speed coupling relationship between the fan rotor 4 and the impeller 5, allowing for independent matching of their optimal operating speeds. It eliminates the need for the fan to maintain a high speed alongside the impeller 5, significantly reducing the strength design requirements and aerodynamic design complexity of the fan blades. Optimizing the fan blades can improve airflow and pressure ratio, thereby increasing the overall thrust and efficiency of the engine. Furthermore, it solves the problems of high machining and assembly precision requirements and frequent vibration associated with traditional single-shaft turbofan engines with multiple support points on a single shaft, reducing the overall machining and assembly difficulty of the shaft system.

[0025] In the embodiments provided by the present invention, the reducer 3 is a planetary gear reducer 3, which includes a sun gear 6, planet gears 7, a planet carrier and an internal gear ring. The sun gear 6 is integrated with the shaft head of the main shaft 2. The planet carrier is fixedly connected to the end of the fan shaft 1. The planet gears 7 are rotatably mounted on the planet carrier and mesh with the sun gear 6. The planet gears 7 mesh with the internal gear ring.

[0026] The reducer 3 is defined as a planetary gear reducer 3, which consists of a sun gear 6, planet gears 7, a planet carrier, and an internal gear ring. The sun gear 6 is integrated with the head of the main shaft 2 and rotates synchronously with the main shaft 2. The planet gears 7 are rotatably mounted on the planet carrier and mesh with the sun gear 6 and the internal gear ring. The planet carrier is fixedly connected to the end of the fan shaft 1. During operation, the main shaft 2 drives the sun gear 6 to rotate, and through gear meshing, drives the planet gears 7 to revolve around the sun gear 6 and rotate on their own axis. The planet gears 7 drive the planet carrier to rotate, thereby transmitting power to the fan shaft 1, realizing power transmission and speed reduction regulation from the main shaft 2 to the fan shaft 1.

[0027] In the embodiments provided by the present invention, the reduction ratio of the planetary gear reducer 3 is adjusted by adjusting the gear ratio of the sun gear 6 and the planet gears 7, and the adjustment range of the reduction ratio is 2:1 to 5:1.

[0028] The reduction ratio of the planetary gear reducer 3 is determined by the gear ratio of the sun gear 6 and the planet gears 7. By adjusting the gear configuration of the two, the reduction ratio can be precisely controlled within the range of 2:1 to 5:1, thereby realizing the step adjustment of the fan shaft speed 1 relative to the main shaft speed 2, and meeting the speed matching requirements of the fan and impeller 5 under different working conditions.

[0029] In the embodiment provided by the present invention, the sun gear 6 is integrated with the front end of the main shaft 2, the impeller 5 is fixed in the middle of the main shaft 2, and the rear end of the main shaft 2 is also fixed with a turbine rotor 8; the turbine rotor 8 is axially locked and fixed to the rear end of the main shaft 2 by a turbine nut 9.

[0030] The sun gear 6 is integrated with the front end of the main shaft 2. The impeller 5 is fixed in the middle of the main shaft 2, and the turbine rotor 8 is fixed in the rear end of the main shaft 2 and axially locked by the turbine nut 9. During operation, the high temperature and high pressure airflow generated by the combustion chamber drives the turbine rotor 8 to rotate. The turbine rotor 8 drives the main shaft 2 to rotate as a whole. The sun gear 6 at the front end of the main shaft 2 transmits power to the planetary reducer 3. The impeller 5 in the middle rotates synchronously with the main shaft 2 to complete air compression, realizing the integrated power output of "turbine rotor 8-main shaft 2-impeller 5 / reducer 3". The locking structure of the turbine nut 9 can prevent the turbine rotor 8 from axially moving under high speed conditions.

[0031] In the embodiments provided by the present invention, the fan shaft 1 and the main shaft 2 adopt a double-support simple support structure, and the fan shaft 1 and the main shaft 2 are respectively equipped with a fan bearing 10 and a main bearing 11 at both ends of the axial direction.

[0032] Both the fan shaft 1 and the main shaft 2 adopt a double-support simple support structure. The fan bearing 10 and the main bearing 11 are respectively configured at their axial ends. The bearings provide radial and axial support constraints for the shaft system, restricting the radial swing and axial movement of the shaft system, so that the fan shaft 1 and the main shaft 2 always maintain a stable axial position when rotating at high speed.

[0033] In the embodiments provided by the present invention, a circumferential anti-rotation structure is provided between the fan rotor 4 and the fan shaft 1, and between the impeller 5 and the main shaft 2. The fan rotor 4 is axially locked and fixed on the fan shaft 1 by a locking nut, and the impeller 5 is axially locked and fixed on the main shaft 2 by a locking nut.

[0034] A circumferential anti-rotation structure is set between the fan rotor 4 and the fan shaft 1, and between the impeller 5 and the main shaft 2 to restrict the relative circumferential rotation between them and ensure that the torque is efficiently transmitted from the shaft to the rotor / impeller 5. At the same time, the fan rotor 4 and the impeller 5 are axially locked by locking nuts to prevent axial movement and circumferential slippage under the action of high-speed centrifugal force and axial force, so as to achieve a rigid connection between the shaft and the components.

[0035] In the embodiments provided by this invention, the circumferential anti-rotation structure is a flat key structure or a spline structure. By limiting the circumferential anti-rotation structure to a flat key structure or a spline structure, the flat key / spline is embedded in the mating keyway of the fan shaft 1-fan rotor 4 and the main shaft 2-impeller 5. Through the contact between the side of the key and the keyway, the relative circumferential movement between the two is restricted, thereby achieving circumferential positioning and torque transmission.

[0036] In the embodiments provided by the present invention, the center lines of the fan shaft 1 and the main shaft 2 are collinear, and the reducer 3 is arranged between the mating ends of the fan shaft 1 and the main shaft 2 to realize torque transmission and speed regulation between the fan shaft 1 and the main shaft 2.

[0037] The fan shaft 1 and the main shaft 2 are set with their center lines collinear. The reducer 3 is precisely positioned between the two mating ends, so that the torque of the main shaft 2 is transmitted to the fan shaft 1 through the reducer 3 along the same straight line. The power transmission path is linear. At the same time, the reducer 3 directly adjusts the speed of the two collinear shafts at this position, realizing "coaxial transmission and local speed adjustment".

[0038] like Figure 2 As shown, P1 is the current ambient pressure, and P2 is the static pressure of the airflow with a higher velocity after being drawn in by the engine. This pressure is less than P1, thus forming a secondary flow from P1 to P2, passing through the fan front bearing and the starter generator. P3 is the airflow pressure after fan compression, and P4 is the airflow pressure after rectification by the fan casing. The rectification effect is deceleration and pressurization, so P4 is greater than P3, thus forming a secondary flow from P4 to P3, passing through the fan rear bearing and the planetary reducer 3.

[0039] It should be noted that any parts not disclosed or specifically described in this invention are existing technologies or conventional configurations, and their specific structures and working principles will not be elaborated further. In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0040] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the invention. Other modifications can be readily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the invention is not limited to the specific details and examples shown and described herein.

Claims

1. A tandem shaft turbofan engine with a planetary reducer, comprising a shaft, a fan rotor, and an impeller, characterized in that, The shaft includes a fan shaft, a main shaft, and a reducer; The fan shaft and the main shaft are connected by a reducer; The fan rotor is fixed on the fan shaft, and the impeller is fixed on the main shaft.

2. A tandem shaft turbofan engine with a planetary reducer according to claim 1, characterized in that, The reducer is a planetary gear reducer, which includes a sun gear, planet gears, a planet carrier, and an internal gear ring. The sun gear is integrated with the shaft head of the main shaft. The planet carrier is fixedly connected to the end of the fan shaft. The planet gears are rotatably mounted on the planet carrier and mesh with the sun gear. The planet gears mesh with the internal gear ring.

3. The tandem shaft turbofan engine with planetary reducer according to claim 2, characterized in that, The reduction ratio of the planetary gear reducer is adjusted by adjusting the ratio of the number of teeth of the sun gear and the planet gears, and the adjustment range of the reduction ratio is from 2:1 to 5:

1.

4. The tandem shaft turbofan engine with planetary reducer according to claim 2, characterized in that, The sun gear is integrated with the front end of the main shaft, the impeller is fixed in the middle of the main shaft, and a turbine rotor is fixed at the rear end of the main shaft. The turbine rotor is axially locked and fixed to the rear end of the main shaft by a turbine nut.

5. A tandem shaft turbofan engine with a planetary reducer according to claim 1, characterized in that, The fan shaft and main shaft adopt a double-support simple support structure, and fan bearings and main bearings are respectively arranged at both ends of the axial direction of the fan shaft and the main shaft.

6. The tandem shaft turbofan engine with planetary reducer according to claim 1, characterized in that, A circumferential anti-rotation structure is provided between the fan rotor and the fan shaft, and between the impeller and the main shaft. The fan rotor is axially locked and fixed to the fan shaft by a locking nut, and the impeller is axially locked and fixed to the main shaft by a locking nut.

7. The tandem shaft turbofan engine with planetary reducer according to claim 6, characterized in that, The circumferential anti-rotation structure is a flat key structure or a spline structure.

8. The tandem shaft turbofan engine with planetary reducer according to claim 1, characterized in that, The fan shaft and the main shaft are arranged with their centerlines collinear, and the reducer is arranged between the mating ends of the fan shaft and the main shaft to realize torque transmission and speed regulation between the fan shaft and the main shaft.

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