Open fan engine with variable pitch system

Abstract

The invention provides an open fan engine with a variable pitch system, which comprises a rotary hydraulic actuating mechanism, an engine low-pressure shaft, a central bevel gear and a plurality of blades, a flywheel shaft of the rotary hydraulic actuating mechanism is connected with the engine low-pressure shaft, and the central bevel gear is mounted outside the engine low-pressure shaft; the blade handle of each blade is provided with an oblique bevel gear, the oblique bevel gears are meshed with the central bevel gear, and the blades are arranged on the tooth portion of the central bevel gear in a surrounding mode through the corresponding oblique bevel gears, so that rotation angle adjustment of the blades is achieved. According to the invention, the paddle can be adjusted and locked at any angle, the size is smaller, the paddle can be modularized to be used in various open fan engines, the design configuration of the existing engine does not need to be greatly changed, and the torsion transmission is stable and reliable. The cylindrical central oblique bevel gear is designed to drive the paddles to rotate, the defect that a circle of connecting rod transmission mechanism needs to be arranged in a traditional adjusting mechanism is overcome, and the overall rigidity is improved.

Description

Technical Field

[0001] The invention relates to the field of open fan engines, and in particular to an open fan engine with a variable pitch system. Background Art

[0002] A propfan engine, also known as an open rotor engine or an unducted fan engine, is a gas turbine engine that uses the power turbine output shaft power to drive the propfan structure. An open fan engine usually has two rows of propfans, the first stage is the rotor, and the second stage is the stator or rotor.

[0003] Propfan engines of the above type require a system for adjusting the angle of the propfan blades, also known as a variable pitch system, to ensure that the power of the engine is always suitable for its operating conditions.

[0004] Generally, the angle adjustment of the stator propeller is relatively simple, and it can be fixed on the engine casing through an actuating mechanism. It drives the connecting rod mechanism through an angular contact ball bearing (thrust bearing) and a sliding pair, and changes the pitch angle of the stator propeller with the help of a four-bar transmission.

[0005] The angle adjustment of the rotor propeller is relatively complicated, and the rotor propeller needs to be forced to rotate around its own propeller axis while rotating around the low-pressure shaft of the engine, so as to achieve the adjustment of the pitch angle. The variable pitch system is the core structure of the open fan engine.

[0006] In the prior art, a variable pitch system has been proposed. The adjustment of the rotor propeller of a traditional open fan engine is basically to push the connecting rod mechanism through the thrust bearing and the sliding pair (or spur gear transmission), and change the pitch angle of the stator propeller with the help of a four-bar transmission. This adjustment mechanism requires the design of a circle (the number is equal to the number of one circle of propellers) of connecting rod mechanism, which makes the weight of the structure very heavy. At the same time, in order to control the angle locking of the blades, the actuating mechanism requires a lot of thrust and tension. Moreover, this structure is expensive and very inconvenient to maintain.

[0007] In view of this, the inventor of the present application has designed an open fan engine with a variable pitch system in order to overcome the above-mentioned technical problems. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide an open fan engine with a variable pitch system in order to overcome the defects of the variable pitch system in the prior art, such as heavy structure, high cost, and inconvenient maintenance.

[0009] The present invention solves the above technical problems through the following technical solutions:

[0010] An open fan engine with a variable pitch system, characterized in that the open fan engine with a variable pitch system comprises a rotary hydraulic actuating mechanism, an engine low-pressure shaft, a central bevel gear and a plurality of blades, the flywheel shaft of the rotary hydraulic actuating mechanism is connected to the engine low-pressure shaft, and the central bevel gear is installed outside the engine low-pressure shaft;

[0011] A bevel gear is installed at the stalk of each blade, and the bevel gear is meshed with the central bevel gear. The blade is surrounded by the corresponding bevel gear at the tooth portion of the central bevel gear to achieve angle adjustment of the blade.

[0012] According to an embodiment of the present invention, the central bevel gear is a cylindrical structure, wherein an inner bevel gear is provided at one end thereof, and the inner bevel gears are matched with the inner bevel gears in a circle.

[0013] According to one embodiment of the present invention, the open fan engine further comprises a flange drum, the outer shell of the rotary hydraulic actuating mechanism is fixedly connected to one end of the flange drum, and the other end of the central bevel gear is fixedly connected to the other end of the flange drum.

[0014] According to one embodiment of the present invention, a ball bearing is provided between the flange drum and the engine low-pressure shaft for supporting the flange drum.

[0015] According to one embodiment of the present invention, the open fan engine further comprises a mounting plate, one end of which is connected to the low-pressure shaft of the engine, and the other end of which is connected to the blade handle of each of the blades.

[0016] According to one embodiment of the present invention, an angle sensor is installed at the petiole of the blade.

[0017] According to one embodiment of the present invention, the rotary hydraulic actuating mechanism includes a first housing, a flywheel shaft, a flywheel and a second housing, the flywheel is mounted on the flywheel shaft, and the flywheel shaft and the flywheel are mounted in a cavity formed by the first housing and the second housing being snap-fitted together through bearings.

[0018] According to one embodiment of the present invention, the flywheel comprises a plurality of flywheel blades distributed at intervals and a cylindrical body, wherein the flywheel blades are installed on the outer wall surface of the cylindrical body at intervals;

[0019] At least one first through hole and at least one second through hole staggered with each other are provided on the cylindrical body between every two adjacent flywheel blades. The first through hole is close to one side corresponding to the flywheel blade, and the second through hole is close to the other side corresponding to the flywheel blade.

[0020] According to one embodiment of the present invention, an oil inlet and an oil outlet are provided on the flywheel shaft, the first through hole is connected to the oil inlet, and the second through hole is connected to the oil outlet;

[0021] Or the second through hole is communicated with the oil inlet, and the first through hole is communicated with the oil outlet.

[0022] According to one embodiment of the present invention, a plurality of blades spaced apart from each other are arranged on the inner wall surface of the first shell, and a boss is arranged at the junction of the blades and the inner wall surface, protruding outward along both sides of the blades; each flywheel blade is located between two adjacent blades.

[0023] According to one embodiment of the present invention, when the flywheel shaft rotates in the first housing and the boss contacts the adjacent flywheel blade, the first through hole or the second through hole is located between the corresponding flywheel blade and the blade and remains unobstructed.

[0024] According to one embodiment of the present invention, the open fan engine further comprises a hydraulic control system, and the hydraulic control system is connected to the oil inlet and the oil outlet.

[0025] The positive and progressive effects of the present invention are:

[0026] The open fan engine with a variable pitch system of the present invention has the following advantages:

[0027] 1. It has a variable pitch system that can adjust and lock the blades at any angle. It is small in size and can be modularly used in various open fan engines. There is no need to make major changes to the existing engine design configuration. The torque transmission is smooth and reliable.

[0028] Second, by designing a cylindrical central bevel gear to drive the rotation of the blades, the disadvantage of the traditional adjustment mechanism that must have a circle of connecting rod transmission mechanism is avoided, and the overall rigidity is improved.

[0029] 3. By designing the gear tooth structure of the central bevel gear as internal teeth, the matching reliability between the central bevel gear and the blade handle pinion is effectively enhanced.

[0030] Fourth, an ingenious rotary hydraulic actuating mechanism is designed to achieve the adjustment and locking of the blades at any angle. It is small in size and can be modularly used in various open fan engines. It can perfectly match the existing hydraulic control system and low-pressure shaft design layout of the engine. There is no need to make major changes to the existing engine design configuration, and it can be easily maintained later.

[0031] 5. The rotary hydraulic actuator has a limit function, making the torque transmission more stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always represent the same features, wherein:

[0033] Figure 1 It is a schematic diagram of the structure of an open fan engine.

[0034] Figure 2 It is a schematic structural diagram of an open fan engine with a variable pitch system according to the present invention.

[0035] Figure 3 It is a schematic diagram of the central bevel gear transmission structure in the open fan engine with a variable pitch system of the present invention.

[0036] Figure 4 It is an exploded view of the rotary hydraulic actuating mechanism in the open fan engine with a variable pitch system of the present invention.

[0037] Figure 5 It is a front view of the rotary hydraulic actuating mechanism in the open fan engine with a variable pitch system of the present invention.

[0038] Figure 6 It is a side view of the rotary hydraulic actuating mechanism in the open fan engine with the variable pitch system of the present invention.

[0039] Figure 7 for Figure 6 Sectional view taken along line AA.

[0040] Figure 8 The present invention is a schematic diagram of the assembly of a flywheel shaft, a flywheel and a first casing in an open fan engine with a variable pitch system.

[0041] Fig. 9 The figure is a schematic diagram of the assembly of the flywheel shaft and the flywheel in the open fan engine with a variable pitch system of the present invention.

[0042] Fig.10 for Fig. 9 The corresponding main view.

[0043] Fig.11 for Fig.10 Cross-sectional view taken along line BB. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0045] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts.

[0046] Furthermore, although the terms used in the present invention are selected from well-known and commonly used terms, some terms mentioned in the present invention specification may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this document.

[0047] Furthermore, it is required that the present invention be understood not only by the actual terms used but also by the meanings connoted by each term.

[0048] like Figure 1 As shown, this embodiment is a traction-type open fan engine 10 , which is a double-row rotor propfan design 11 , including an aircraft fuselage 12 and an engine air inlet 13 .

[0049] like Figure 2 As shown, the present invention discloses an open fan engine with a variable pitch system, which includes a rotary hydraulic actuator 100, an engine low-pressure shaft 200, a central bevel gear 300 and a plurality of blades 400. The flywheel shaft 110 of the rotary hydraulic actuator 100 is connected to the engine low-pressure shaft 200, and the central bevel gear 300 is installed outside the engine low-pressure shaft 200. A bevel gear 410 is installed at the shank of each blade 400, and the bevel gear 410 is meshed with the central bevel gear 300. The blade 400 is surrounded by the corresponding bevel gear 410 and arranged at the tooth portion of the central bevel gear 300, so that the rotation angle of the blade 400 is adjusted.

[0050] like Figure 3 As shown, the central bevel gear 300 is preferably a cylindrical structure, wherein one end is provided with an inner bevel gear 310, and the bevel gears 410 are respectively matched with the inner bevel gears 310 in a circle. The central bevel gear 300 contacts the bevel gear 410 at the handle of the blade 400 to achieve the rotation angle adjustment of the blade 400.

[0051] Combination Figure 2 The open fan engine further includes a flange drum 500 , which fixes the outer shell of the rotary hydraulic actuating mechanism 100 to one end of the flange drum 500 , and the other end of the central bevel gear 300 to the other end of the flange drum 500 .

[0052] For example, the left and right end shells of the rotary hydraulic actuator 100 and the flange drum 500 are fixedly connected through a bolt hole 520 (1 series 3). The flange drum 500 is connected to the central bevel gear 300 through a circle of screws. Further, other methods can be used for connection as needed.

[0053] Furthermore, in order to enhance the stability of the transmission, a ball bearing 510 may be provided between the flange drum 500 and the engine low-pressure shaft 200 to support the flange drum 500. A ball bearing 510 is used as a fulcrum, and there are fixing devices on the left and right of the ball bearing 510.

[0054] Furthermore, the open fan engine also includes a mounting plate 600 , one end of which is connected to the engine low-pressure shaft 200 , and the other end of which is connected to the petiole 420 of each blade 400 .

[0055] The mounting plate 600 of the blade 400 is connected to the engine low-pressure shaft 200 through a spline, and an angle sensor 430 is installed at the blade handle 420 of the blade 400. The spline is axially fixed to the boss of the engine low-pressure shaft 200 through nuts before and after. The engine cap 800 is fixed to the mounting plate 600 through a casing 810. The entire structure is arranged in the engine inner cavity 900. The blade bone 440 is fixedly connected to the engine cap 800.

[0056] like Figures 4 to 7 As shown, the rotary hydraulic actuator 100 includes a first housing 110, a flywheel shaft 120, a flywheel 130, and a second housing 140. The flywheel 130 is mounted on the flywheel shaft 120. The flywheel shaft 120 and the flywheel 130 are mounted in a cavity formed by the snap-fit ​​connection between the first housing 110 and the second housing 140 through a bearing 150. A sealing ring 160 is provided between the first housing 110 and the second housing 140, between the flywheel shaft 120 and the first housing 110, and between the flywheel shaft 120 and the second housing 140, so as to achieve a sealed connection.

[0057] like Figures 9 to 11 As shown, the flywheel 130 includes a plurality of flywheel blades 131 and a cylindrical body 132, wherein the flywheel blades 131 are installed at intervals on the outer wall surface of the cylindrical body 132. At least one first through hole 133 and at least one second through hole 134 are staggered on the cylindrical body 132 between every two adjacent flywheel blades 131. The first through hole 133 is close to the corresponding flywheel blade 131 on one side, and the second through hole 134 is close to the corresponding flywheel blade 131 on the other side.

[0058] At the same time, the flywheel shaft 120 is provided with an oil inlet 121 and an oil outlet 122, so that the first through hole 133 is connected to the oil inlet 121, and the second through hole 134 is connected to the oil outlet 122. Alternatively, the second through hole 134 is connected to the oil inlet 121, and the first through hole 133 is connected to the oil outlet 122.

[0059] Combination Figure 8 As shown, a plurality of blades 111 spaced apart from each other are arranged on the inner wall surface of the first housing 110, and a boss 112 is arranged at the junction of the blade 111 and the inner wall surface of the first housing 110, protruding outward along both sides of the blade 111. Each flywheel blade 131 is located between two adjacent blades 111. Due to the design of the boss 112 on the blade 111 on the first housing 110, the rotary hydraulic actuating mechanism 100 has a maximum adjustable range limit, thereby ensuring the safety of the adjustment mechanism.

[0060] When the flywheel shaft 120 rotates in the first housing 110 and the boss 112 contacts the adjacent flywheel blade 131 , the first through hole 133 or the second through hole 134 is located between the corresponding flywheel blade 131 and the blade 111 and remains unobstructed.

[0061] Combination Figure 2 As shown, the open fan engine further includes a hydraulic control system 700 , which is connected to the oil inlet 121 and the oil outlet 122 .

[0062] According to the above structural description, in the open fan engine with a variable pitch system of the present invention, the rotary hydraulic actuating mechanism 100 adopts a modular form. For the convenience of explanation, this embodiment takes the adjustment mechanism model of the first-stage rotor blades for detailed description. The left end of the flywheel shaft 120 of the rotary hydraulic actuating mechanism 100 is connected to the rotary hydraulic joint 160. The left end of the rotary hydraulic joint 160 is a stationary component, and the oil inlet 121 and the oil outlet 122 located at the rotary hydraulic joint 160 are connected to the hydraulic control system 700. Furthermore, the hydraulic control system 700 can share the same set with the control system of the engine itself. The flywheel shaft 120 of the rotary hydraulic actuating mechanism 100 is connected to the low-pressure shaft 200 of the engine, and the connection method (not marked in the figure) can use the common shaft-to-shaft connection method.

[0063] The pitch adjustment principle of the open fan engine with a pitch control system of the present invention is:

[0064] The engine low-pressure shaft 200 drives the mounting plate 600 to rotate through the spline, and the mounting plate 600 drives the blades 400 to rotate around the engine low-pressure shaft 200. The right end 123 of the flywheel shaft 120 of the rotary hydraulic actuating mechanism 100 is fixedly connected to the engine low-pressure shaft 200, and the housing of the rotary hydraulic actuating mechanism 100 is fixedly connected to the central bevel gear 300 through the flange drum 500.

[0065] When the angle of the blade 400 does not need to be adjusted, the first housing 110 of the rotary hydraulic actuator 100 and the flywheel shaft 120 are hydraulically matched to achieve mutual angular locking between the first housing 110 and the flywheel shaft 120, thereby achieving mutual angular locking between the central bevel gear 300 and the engine low-pressure shaft 200, that is, mutual locking between the blade 400 and the engine low-pressure shaft 200. In this way, the locking of the angle of the blade 400 is completed.

[0066] When the blades 400 need to be adjusted, the hydraulic control system 700 is started, driving the hydraulic pressure on both sides of the chamber 113, pushing the flywheel blades 131 on the flywheel shaft 120 and the blades 111 of the first housing 110 to rotate with each other. Through the above-mentioned transmission relationship, that is, the central bevel gear 300 and the engine low-pressure shaft 200 rotate with each other, so that the blades 400 achieve self-rotation.

[0067] When the angle sensor 430 at the blade stalk recognizes that the angle is adjusted in place, it feeds back to the hydraulic control system 700, and the hydraulic control system 700 locks the hydraulic pressure at this time, so that the entire variable pitch system is locked, and the rotation adjustment of the blade 400 is completed.

[0068] The open fan engine with a variable pitch system of the present invention has a rotatable hydraulic actuator. When the blades do not need to be adjusted, the hydraulic actuator and the transmission mechanism can rotate around the low-pressure shaft of the engine together with the blades without generating a relative rotation angle. When the blades need an angle, the hydraulic actuator can push the central bevel gear, and then the central bevel gear pushes the small bevel gear at the blade handle, thereby realizing the self-rotation angle adjustment of the blades in the rotating state.

[0069] The open fan engine with variable pitch system has the following characteristics:

[0070] 1. Abandoning the traditional connecting rod mechanism, a cylindrical central bevel gear 300 is used to drive the blade handle to rotate. Figure 3 .

[0071] Furthermore, the present invention suggests that the gear structure of the central bevel gear is an internal bevel gear, while the small bevel gear at the blade petiole is an inverted bevel gear that is small at the top and large at the bottom. This design is because when the blade rotates around the low-pressure shaft of the engine, a very large centrifugal load will be generated, and the small bevel gear at the petiole will tend to displace radially outward. The use of the internal bevel gear suggested by the present invention and the inverted bevel gear of the petiole can effectively prevent the central bevel gear from disengaging from the small bevel gear at the petiole, resulting in unstable contact. In addition, such a design can effectively enhance the rigidity of the central bevel gear transmission mechanism.

[0072] Second, the present invention proposes a novel rotary hydraulic actuating mechanism 100, which has been modularized and can be conveniently installed in various open fan engine pitch adjustment systems. A suitable flange drum can be designed according to needs, the rotary hydraulic actuating mechanism housing is fixedly connected to the above-mentioned central bevel gear, and the flywheel shaft of the rotary hydraulic actuating mechanism is fixedly connected to the low-pressure shaft 3 of the engine.

[0073] The first housing has a blade structure, which forms many chambers with the flywheel blades on the flywheel shaft. The flywheel shaft has oil holes, so each chamber has an oil hole. When actuation is required, hydraulic oil enters the chamber through the oil holes, and the hydraulic pressure of the chambers on both sides is coordinated to push the blades to rotate relative to each other. In this way, the first housing and the flywheel shaft can rotate relative to each other, that is, the low-pressure shaft of the engine and the central bevel gear can rotate relative to each other. Finally, the central bevel gear pushes the inverted bevel gear at the handle, so that the blade can achieve self-rotation adjustment.

[0074] 3. An oil circuit is designed in the flywheel shaft of the rotary hydraulic actuator, and the hydraulic oil is led out through one end and passed through a rotary hydraulic joint. One end of the rotary hydraulic joint is a rotor, which is connected to the oil hole of the flywheel shaft. The other end of the rotary hydraulic joint is a stator, which is connected to the hydraulic control system. The hydraulic system has an electromagnetic reversing valve that can drive the hydraulic pressure forward and reverse to push the flywheel blades and blades in the rotary hydraulic actuator to rotate clockwise and counterclockwise, thereby achieving clockwise and counterclockwise rotation angle adjustment of the blades. The hydraulic pressure also has a pressure relief valve to prevent excessive hydraulic pressure from causing damage to the actuator.

[0075] Fourth, an angle sensor is installed at the blade stalk. When the rotary hydraulic actuator is adjusted, the control system adjusts the angle of the blade in real time according to feedback information from multiple (for example, 8) sensors.

[0076] 5. The rotary hydraulic actuator also has a limit function. Usually, the clockwise and counterclockwise rotation of the blades has a certain adjustable range. According to this range, the span of the flywheel blades on the flywheel shaft can be designed. In this way, the blades of the first housing can only rotate within the span angle of the flywheel blades, which plays a limit protection role and prevents excessive adjustment of the blades.

[0077] 6. The rotary hydraulic actuator also has a blade angle locking function. After the blade angle is adjusted, it is usually necessary to lock its angle so that it can work normally. In the present invention, the rotary hydraulic actuator can lock the flywheel blade and the blade at any angle through the hydraulic coordination on both sides of the chamber (the cavity between the flywheel blade and the blade), and then the hydraulic oil circuit valve is closed.

[0078] Therefore, the angle of the blade can be locked. Thus, the present invention can reduce the disadvantage of the traditional blade locking structure causing extra weight.

[0079] For those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary implementation of the present application.

[0080] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0081] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. An open fan engine with a variable pitch system, characterized in that: The open fan engine with a variable pitch system comprises a rotary hydraulic actuating mechanism, an engine low-pressure shaft, a central bevel gear and a plurality of blades, wherein the flywheel shaft of the rotary hydraulic actuating mechanism is connected to the engine low-pressure shaft, and the central bevel gear is installed outside the engine low-pressure shaft; A bevel gear is installed at the stalk of each blade, and the bevel gear is meshed with the central bevel gear. The blade is surrounded by the corresponding bevel gear at the tooth portion of the central bevel gear to achieve angle adjustment of the blade.

2. The open fan engine with a variable pitch system according to claim 1, characterized in that: The central bevel gear is a cylindrical structure, one end of which is provided with an inner bevel gear, and the bevel gears are respectively matched with the inner bevel gears in a circle.

3. The open fan engine with a variable pitch system as claimed in claim 2, characterized in that: The open fan engine also includes a flange drum, the housing of the rotary hydraulic actuating mechanism is fixedly connected to one end of the flange drum, and the other end of the central bevel gear is fixedly connected to the other end of the flange drum.

4. The open fan engine with a variable pitch system according to claim 3, characterized in that: A ball bearing is arranged between the flange drum and the engine low-pressure shaft for supporting the flange drum.

5. The open fan engine with a variable pitch system according to claim 1, characterized in that: The open fan engine also includes a mounting plate, one end of which is connected to the low-pressure shaft of the engine, and the other end of which is connected to the blade handle of each blade.

6. The open fan engine with a variable pitch system according to claim 5, characterized in that: An angle sensor is installed at the petiole of the blade.

7. The open fan engine with a variable pitch system according to claim 1, characterized in that: The rotary hydraulic actuating mechanism comprises a first housing, a flywheel shaft, a flywheel and a second housing. The flywheel is mounted on the flywheel shaft. The flywheel shaft and the flywheel are mounted in a cavity formed by the first housing and the second housing being snap-fitted together via bearings.

8. The open fan engine with a variable pitch system according to claim 7, characterized in that: The flywheel comprises a plurality of flywheel blades distributed at intervals and a cylindrical body, wherein the flywheel blades are installed on the outer wall surface of the cylindrical body at intervals; At least one first through hole and at least one second through hole staggered with each other are provided on the cylindrical body between every two adjacent flywheel blades. The first through hole is close to one side corresponding to the flywheel blade, and the second through hole is close to the other side corresponding to the flywheel blade.

9. The open fan engine with a variable pitch system according to claim 8, characterized in that: An oil inlet and an oil outlet are provided on the flywheel shaft, the first through hole is connected to the oil inlet, and the second through hole is connected to the oil outlet; Or the second through hole is communicated with the oil inlet, and the first through hole is communicated with the oil outlet.

10. The open fan engine with a variable pitch system according to claim 8, characterized in that: A plurality of blades spaced apart from each other are arranged on the inner wall surface of the first shell, and a boss is arranged at the junction of the blade and the inner wall surface, protruding outward along both sides of the blade; each flywheel blade is located between two adjacent blades.

11. The open fan engine with a variable pitch system according to claim 10, characterized in that: When the flywheel shaft rotates in the first housing and the boss contacts the adjacent flywheel blades, the first through hole or the second through hole is located between the corresponding flywheel blade and the blade and remains unobstructed.

12. The open fan engine with a variable pitch system according to claim 9, characterized in that: The open fan engine also includes a hydraulic control system, which is connected to the oil inlet and the oil outlet.

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