A turbofan engine with a reducer driving a fan

Abstract

A turbofan engine with a reducer driving a fan includes a fan unit body, a low-turbine unit body, a core engine, a shaft system, a supporting assembly and a reducer, the fan unit body including a fan rotor; the low-turbine unit body including a low-pressure turbine; the shaft system including a low-pressure shaft and a high-pressure shaft, the high-pressure shaft being used to support the core engine; the supporting assembly including an intermediate bearing and a rear bearing; wherein the low-pressure turbine is supported on the low-pressure shaft through at least the rear bearing, the fan rotor is supported at the front end of the low-pressure shaft through the intermediate bearing, the reducer is arranged between the fan rotor and the low-pressure shaft, the input end is connected with the low-pressure shaft, the output end is connected with the fan rotor, and the reducer is used to transmit the rotating moment of the low-pressure turbine to the fan rotor to drive the fan rotor to operate. The above turbofan engine has a simplified engine new structure.

Description

Technical Field

[0001] This invention relates to the field of engines, and more specifically to a turbofan engine with a reducer driving a fan. Background Technology

[0002] Aero engines are complex in structure, with a large number and variety of parts. The manufacturing precision of these parts is high, and the assembly of components and the entire engine is extremely difficult. Currently, conventional aero engine support schemes typically involve 5-8 support points, with the load-bearing casing generally requiring 3-4. The large number of parts results in a persistently high overall weight, significantly limiting further improvements in thrust-to-weight ratio. Furthermore, the large number of parts leads to lower overall reliability and increased assembly difficulty. Since nearly 80% of the thrust of a high-bypass turbofan engine is provided by the fan, maximizing fan efficiency while appropriately reducing internal thrust is a future trend in aero engine development. Summary of the Invention

[0003] One object of the present invention is to provide a turbofan engine with a speed reducer-driven fan, which can simplify the structure of an aircraft engine.

[0004] The turbofan engine for achieving the above objectives includes a fan unit, a low-pressure turbine unit, a core engine, a shaft system, a support assembly, and a reducer. The fan unit includes a fan rotor; the low-pressure turbine unit includes a low-pressure turbine; the shaft system includes a low-pressure shaft and a high-pressure shaft, the high-pressure shaft supporting the core engine; the support assembly includes an intermediate bearing and a rear bearing; wherein the low-pressure turbine is supported on the low-pressure shaft at least via the rear bearing, the fan rotor is supported at the front end of the low-pressure shaft via the intermediate bearing, and the reducer is disposed between the fan rotor and the low-pressure shaft, the input end of the reducer being connected to the low-pressure shaft and the output end being connected to the fan rotor, for transmitting the rotational torque of the low-pressure turbine to the fan rotor to drive the fan rotor to operate.

[0005] In one or more embodiments, the reducer is a planetary gear reducer, a star-shaped transmission reducer, or a two-stage reducer.

[0006] In one or more embodiments, the reducer is a galactic gearbox, including a sun gear, a plurality of planet gears, an internal gear ring, an input shaft system, and an output shaft system, wherein the reducer receives torque from the low-pressure shaft via the input shaft system and the sun gear, and outputs torque to the fan rotor via the internal gear ring and the output shaft system to drive the fan rotor.

[0007] In one or more embodiments, the output shaft system includes an output shaft connected to the fan shafts of the internal gear ring and the fan rotor, respectively, and the input shaft system includes an input shaft connected to the front end of the low-pressure shaft and the internal spline of the sun gear, respectively.

[0008] In one or more embodiments, the output shaft is provided with an external spline at its front end for connection with the internal spline of the fan shaft, and the input shaft is provided with an external spline for connection with the internal spline of the sun gear.

[0009] In one or more embodiments, the input shaft and output shaft of the reducer are coaxial.

[0010] In one or more embodiments, the fan unit further includes a fan housing, and the fan rotor includes a fan shaft and fan blades, with the fan housing and the fan rotor positioned by bearings.

[0011] In one or more embodiments, when the reducer is the galactic gearbox, the reduction ratio ranges from 3 to 9; or when the reducer is a two-stage reducer, multiple reducers are connected in series.

[0012] In one or more embodiments, the core machine includes a high-pressure compressor, a combustion chamber, and a high-pressure turbine, wherein the high-pressure compressor has 6 to 11 stages, the high-pressure turbine has 1 stage, and the low-pressure turbine has 1 to 3 stages.

[0013] In one or more embodiments, the support assembly further includes a front bearing.

[0014] In one or more embodiments, the turbofan engine further includes a core engine casing and an intermediate casing, the intermediate casing being disposed between the core engine casing and the fan casing, the intermediate casing employing a design that integrates the fan rectifier with the intermediate casing support plate.

[0015] The aforementioned turbofan engine drives the fan rotor through a reducer, eliminating the original fan booster stage and the original 5-8 support point design, which simplifies the engine structure and reduces assembly difficulty. Attached Figure Description

[0016] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0017] Figure 1 This is a simplified structural diagram of an existing aero-engine;

[0018] Figure 2 This is a simplified structural diagram of one embodiment of a turbofan engine;

[0019] Figure 3 This is a schematic diagram of the meshing relationship between the fan shaft and the galaxy reduction gearbox;

[0020] Figure 4 This is a schematic diagram of one embodiment of the fan plate;

[0021] Figure 5 This is a schematic diagram of one embodiment of the galactic reduction gearbox;

[0022] Figure 6 This is a schematic diagram of an embodiment of an internal gear ring;

[0023] Figure 7 This is a structural schematic diagram of one embodiment of a low-pressure shaft. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0025] It should be noted that these and other accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0026] Figure 1 The diagram illustrates the structure of a conventional aero-engine. A typical aero-engine support system involves 5-8 support points, such as the first support point 1, the second support point 2, the third support point 3, the fourth support point 4, and the fifth support point 5. Three to four load-bearing casings are generally required, such as the fan casing 7, the intermediate casing 610, the interstage casing 8, and the low-pressure turbine stator casing 10. A booster stage 11 and a fan rectifier 6 are located behind the fan for guiding and pressurizing the gas. The presence of these components makes the engine structure complex, with a large number and variety of parts, difficult assembly, and poor reliability. It also limits further increases in thrust-to-weight ratio.

[0027] The turbofan engine disclosed herein effectively simplifies the engine structure and maximizes the efficiency of the fan. (See reference...) Figures 2 to 6 The turbofan engine comprises a fan unit 20, a low-pressure turbine unit 30, a core engine 40, a shaft system 50, support components, and a reduction gear 70. The support components include an intermediate bearing 61, a front bearing 62, and a rear bearing 63, which are the engine's main support points. The low-pressure turbine unit 30 includes a low-pressure turbine 31. The shaft system 50 includes a low-pressure shaft 51 and a high-pressure shaft 52. The high-pressure shaft 52 supports the core engine 40. The low-pressure turbine 31 is supported on the low-pressure shaft 51 at least via the rear bearing 63. The fan rotor 21 is supported at the front end of the low-pressure shaft 51 via the intermediate bearing 61.

[0028] The core engine 40 includes a combustion chamber, a high-pressure compressor, and a high-pressure turbine, as well as a core engine casing 44, which includes a compressor stator casing, a combustion chamber casing, and a turbine casing. The core engine casing supports the internal high-pressure core rotor. The high-pressure compressor rotor's function is to compress air; the air for the first-stage blades comes from the fan.

[0029] The fan unit 20 includes a fan rotor 21 and a fan housing 22. An intermediate housing 610 is located between the fan housing 22 and the core housing 44, employing a rectifier and support plate integrated design. The fan housing 22 and the intermediate housing 610 are connected by mounting bolts. The fan housing 22 provides support for the fan rotor, and the fan housing 22 and the fan rotor 32 are positioned together by bearings. Specifically, the fan rotor 21 includes a fan shaft 211 and fan blades 212. The fan blades 212 are mounted on the fan shaft 211, which has an inner bearing ring that rotates with it. The outer bearing ring is mounted on a spring support on the fan housing 211. The spring support of the fan housing includes a bearing seat structure.

[0030] There is a clearance between the fan blades and the fan casing. The blade tip clearance needs to be indirectly controlled by adjusting the inner diameter of the casing and the outer diameter of the rotor blade tips. The blade tips of the fan rotor need to be ground. Grinding the fan rotor blade tips can effectively control the cold-state values ​​of the blade tip diameter and blade tip clearance. The blade tip clearance between the fan casing and the fan rotor needs to be measured after assembly.

[0031] The fan speed is reduced by a speed reducer 70, which is located between the fan rotor 21 and the low-pressure shaft 51. The input end is connected to the low-pressure shaft 51, and the output shaft is connected to the fan rotor 21. It is used to transmit the rotational torque of the low-pressure turbine 31 to the fan rotor 21 to drive the fan rotor. Therefore, the structure of the speed reducer 21 needs to withstand long-term navigation operation.

[0032] In one embodiment, the reducer is a planetary gear reducer, a star-shaped transmission reducer, or a two-stage reducer. When the reducer is a planetary gear reducer, the input end is driven by a low-frequency vortex, and the output end drives a fan disc, with a reduction ratio range of 3 to 9; or when the reducer is a two-stage reducer, multiple reducers can be connected in series, such as using two reducers with a reduction ratio of 3 connected in series.

[0033] Figure 3 , Figure 5The diagram shows a simplified structure of the reducer 70 using a galaxy-like reduction structure. This structure is compact, and its main rotary structure is suitable for reducing the speed of a rotary shaft in engine-type applications. The galaxy reducer 70 includes an input shaft system 71, a sun gear 72, multiple planetary gears 73, a support 74, an internal gear ring 75, and an output shaft system 76. The reducer 70 receives torque from the low-pressure shaft 51 via the input shaft system 71 and the sun gear 72, and outputs torque to the fan shaft via the internal gear ring 75 and the output shaft system 76 to drive the fan rotor 21.

[0034] Specifically, the output shaft system includes an output shaft, and the input shaft system includes a first input shaft. The output shaft is connected to the internal gear ring and the fan shaft, respectively, and the input shaft is connected to the front end of the low-pressure shaft and the sun gear, respectively. Further, the input shaft system includes three components: the front end of the low-pressure shaft, the connecting sleeve gear shaft, and the first input shaft.

[0035] The front end of the low-pressure sleeve gear shaft is the first input shaft, and the rear end is the front end of the low-pressure sleeve shaft. The first input shaft is connected to the low-pressure sleeve gear shaft by bolts. Through the connecting sleeve gear shaft, the front end of the low-pressure shaft transmits torque to the first input shaft. The front end of the first input shaft is machined with external splines, which mate with the internal splines of the sun gear.

[0036] The front end of the low-pressure shaft mates with a connecting sleeve gear shaft via a spline. The spline is used for positioning and transmission with the low-pressure shaft. (Refer to...) Figure 7 The diagram shows the structure of the low-pressure turbine shaft. A, A', and A” represent the threaded portion, B, B', and B” represent the bearing housing, and C represents the external spline portion. The front end of the low-pressure shaft 51, i.e. Figure 7 The left end A' shown has a thread. After the low-pressure shaft 51 passes through the connecting sleeve teeth, a nut is tightened onto the front end of the low-pressure shaft. The nut presses against the connecting sleeve teeth, and the front end of the low-pressure shaft and the connecting sleeve teeth are connected together by a large nut. The main function of the large nut installed at the front end of the low-pressure shaft is to axially press the low-pressure shaft and the connecting sleeve teeth shaft. Circumferential positioning relies on the external spline at the front end of the low-pressure shaft and the internal spline on the connecting sleeve teeth shaft.

[0037] Return to reference Figure 5 The galaxy deceleration structure shown has a sun gear 72 located at the center of the entire galaxy. The module design of the sun gear's teeth needs to consider long-term load-bearing capacity. The number of teeth on the sun gear needs to be set according to the reduction ratio. Multiple planetary gears 73 are arranged around the sun gear 72, distributed in all directions around it. For example, with three planetary gears, the lines connecting the axes of the three planetary gears 73 to the center of the shaft system are 120 degrees apart. Planet carriers 74 are mounted on the axes of the planetary gears 73, and are evenly distributed around the sun gear 72. The planet carriers 74 and planetary gears 73 are connected by bearings. Thus, the galaxy deceleration scheme uses a fixed planet carrier method. The planetary reducer has its own bearings, ensuring smooth and reliable operation of the reducer's output shaft. A preferred scheme is three evenly distributed planetary gears for uniform force distribution.

[0038] The outer ring of planetary gear 73 is mated with the internal gear ring 75, and the engagement... Figure 6 As shown, the internal gear ring 75 serves as the support and meshing track for the planetary gears 73. The internal gear ring 75 has a number of teeth set according to the transmission ratio. Because the planetary support is fixed, the internal gear ring 75 rotates relative to the planetary gears 73. The internal gear ring 75 is connected to the first output shaft, and its center is bolted to the first output shaft.

[0039] In a more specific embodiment of the output shaft system, an internal gear ring is connected to a first output shaft 76, and the center of the internal gear ring is connected to the first output shaft 76 by bolts. The first output shaft is connected to a second output shaft, and the second output shaft is connected to a fan shaft 211. The front end of the second output shaft has an external spline 77 for connecting to the internal spline 213 of the fan shaft 211. The fit between the internal and external splines needs to facilitate assembly and disassembly, while also meeting the requirements of circumferential positioning and torque transmission.

[0040] In some embodiments, such as Figure 6 The internal gear ring structure shown illustrates the shoulder 1111, thread 1112, and teeth 1113. In this case, the internal gear ring directly serves as the first output shaft, and the external spline of the internal gear ring is connected to the internal spline of the fan disc to drive the fan.

[0041] Therefore, the internal gear ring is connected to the internal spline of the fan shaft 211 via the output shaft 76 to drive the fan. Through planetary gear transmission, since the mechanism has planetary gears on the moving axis, by selecting a suitable load-sharing device, the entire transmission load can be evenly distributed across multiple planetary gears, and the power distribution can improve the working life of each load-bearing gear. A preferred scheme is a three-planetary-gear evenly distributed configuration to achieve uniform force distribution.

[0042] The input and output shafts of a planetary reduction gear are coaxial, which plays an important role in reducing the space required for the reducer and allows it to be made more compact.

[0043] The main support points of the engine are the front bearing 62 and the rear bearing 63, with the intermediate bearing at the fan disk serving as an auxiliary support point. The fan is supported on the front end of the low-pressure turbine shaft via the intermediate bearing 61. The inner ring speed of the bearing is higher with the low-pressure turbine, while the outer ring speed is lower with the gearbox's internal gear ring. The load-bearing capacity of the intermediate bearing 61 must be sufficient to bear the radial and axial loads from the front end of the fan and gearbox during engine operation.

[0044] As a result, the engine is supported by the front and rear pivots, and the number of pivot bearings is reduced from 5 to 2 compared to the traditional twin-rotor turbofan engine. Since the engine has only two pivots, the number of casings is reduced from 3-4 to 2 compared to the traditional twin-rotor turbofan engine, with only the intermediate casing and interstage casing remaining.

[0045] The operation of a turbofan engine is as follows. The fan is located at the very front of the engine, providing thrust. The gearbox is positioned between the fan rotor and the low-pressure shaft. The compressor rotor compresses the air supplied by the fan and sends it into the combustion chamber. The combustion chamber pushes the combusted air towards the blades of the high-pressure turbine rotor, which rotates and compresses the airflow under the pressure of the airflow output from the combustion chamber. The core engine serves two main purposes: generating internal thrust and primarily driving the fan via the low-pressure turbine through the gearbox.

[0046] The airflow from the high-pressure turbine rotor impacts the blades of the low-pressure turbine rotor, ultimately driving the rotation of the low-pressure turbine rotor. The low-pressure turbine rotor is connected to a reducer via a low-pressure shaft, driving the reducer's rotation. Through the reducer, the fan rotor's speed is reduced, but the input torque of the fan rotor increases. The rotation of the fan rotor causes the airflow to move backward; due to the reaction force of the airflow, the fan rotor drives the engine casing forward via bearings.

[0047] To maximize the advantages of the fan, the fan speed can be further reduced, the fan blade diameter increased, the bypass flow rate improved, the engine bypass ratio increased, and the bypass thrust increased. Since the low-pressure turbine drives only 31 fans and its work capacity requirements are not high, the number of compressor and turbine stages can be further reduced. For example, the high-pressure compressor stage range can be 6 to 11 stages, the high-pressure turbine stage can be 1 stage, and the low-pressure turbine stage range can be 1 to 3 stages. The axial dimension of the gas generator can be reduced by approximately 400 mm, and the overall axial dimension can be reduced by approximately 200 mm.

[0048] Therefore, the turbofan engine eliminates the turbocharger stage, thereby eliminating the first and second pivot components. The reduced axial dimension leads to a smaller pivot span. The fan rectifier and intermediate casing support plate are integrated into a single design, resulting in a compact structure between the fan and the intermediate casing. This reduces the axial dimension by approximately 1100mm, increases rotor support stiffness, and improves both axial dimension and thrust-to-weight ratio. To maximize fan performance, the fan diameter can be appropriately increased, and the fan speed can be appropriately reduced. If the low-pressure rotor speed is 9000rpm, the fan speed can be as low as 1000rpm. Fan blade strength should be further enhanced. Although the internal thrust decreases, the increased fan blade diameter and bypass ratio result in increased external thrust, leading to an overall increase in engine thrust. This structure significantly reduces the number of engine parts, such as bearings and casings, reducing the number of parts to approximately one-third of the original. This results in a lower overall engine weight, reduced assembly difficulty, and higher reliability.

[0049] It should be noted that the use of terms such as "first" and "second" to define the components in the above content is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application.

[0050] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0051] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A turbofan engine with a speed reducer driving a fan, characterized in that, include: Fan unit, including fan rotor; Low-vortex unit, including low-pressure turbine; Core machine; The shafting system includes a low-pressure shaft and a high-pressure shaft, wherein the high-pressure shaft is used to support the core machine. Support components, including intermediate bearings and rear bearings; and reducer; The low-pressure turbine is supported on the low-pressure shaft at least by the rear bearing, the fan rotor is supported at the front end of the low-pressure shaft by the intermediate bearing, and the reducer is disposed between the fan rotor and the low-pressure shaft. The input end of the reducer is connected to the low-pressure shaft, and the output end is connected to the fan rotor, for transmitting the rotational torque of the low-pressure turbine to the fan rotor to drive the fan rotor to operate.

2. The engine as claimed in claim 1, characterized in that, The reducer is a planetary gear reducer, a star-shaped transmission reducer, or a two-stage reducer.

3. The engine as described in claim 2, characterized in that, This reducer features a galaxy-like speed reduction structure, including a sun gear, multiple planetary gears, an internal gear ring, an input shaft system, and an output shaft system. The reducer receives torque from the low-pressure shaft via the input shaft system and the sun gear, and outputs torque to the fan rotor via the internal gear ring and the output shaft system to drive the fan rotor.

4. The engine as described in claim 3, characterized in that, The output shaft system includes an output shaft, which is connected to the fan shaft of the internal gear ring and the fan rotor, respectively. The input shaft system includes an input shaft, which is connected to the low-pressure shaft and the sun gear, respectively.

5. The engine as described in claim 4, characterized in that, The output shaft has an external spline at its front end for connection with the internal spline of the fan shaft, and the input shaft has an external spline for connection with the internal spline of the sun gear.

6. The engine as claimed in claim 2, characterized in that, The input and output shafts of the reducer are coaxial.

7. The engine as claimed in claim 1, characterized in that, The fan unit also includes a fan housing, and the fan rotor includes a fan shaft and fan blades. The fan housing and the fan rotor are positioned by bearings.

8. The engine as claimed in claim 2, characterized in that, When the reducer is a planetary gear reducer, the reduction ratio range is 3 to 9; or when the reducer is a two-stage reducer, multiple reducers are connected in series.

9. The engine as claimed in claim 1, characterized in that, The core machine includes a high-pressure compressor, a combustion chamber, and a high-pressure turbine. The high-pressure compressor has 6 to 11 stages, the high-pressure turbine has 1 stage, and the low-pressure turbine has 1 to 3 stages.

10. The engine as claimed in claim 1, characterized in that, The support assembly also includes a front bearing.

11. The engine as claimed in claim 1, characterized in that, The turbofan engine also includes a core engine casing and an intermediate casing. The intermediate casing is located between the core engine casing and the fan casing. The intermediate casing adopts a design that integrates the fan rectifier with the intermediate casing support plate.

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