A main reduction gear, fixed support structure and rotary wing aircraft

Abstract

The application relates to the technical field of aviation equipment, and discloses a main speed reducer, a fixed support structure and a rotor aircraft. The main speed reducer comprises a rotor shaft structure and a speed reduction main body. The rotor shaft structure and the speed reduction main body can be assembled and separated, are convenient to independently disassemble, do not need to be disassembled for the complex rotor shaft structure connected with the helicopter interface, thereby significantly reducing the disassembling steps required in the maintenance operation, and reducing the fault checking and maintenance difficulty. The speed reduction main body part of the main speed reducer is a fault-prone area, and the rotor shaft structure is highly integrated with interfaces of a flight control system, an electrical system and the like. Through the split type structure design of the application, when a fault occurs, only the speed reduction main body needs to be disassembled for factory maintenance, without intervention of the rotor shaft structure, so that the average repair time of the main speed reducer is greatly shortened, and the maintenance efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of aviation equipment technology, specifically to a main gear reducer, a fixed support structure, and a rotorcraft. Background Technology

[0002] As the core component of the helicopter's rotor drive system, the main gearbox converts the high-speed, low-torque power output from the engine into the low-speed, high-torque power required by the rotor to ensure normal helicopter flight. Due to the strong integral structure of the main gearbox, the rotor shaft assembly is tightly connected to the inside of the main gearbox and is usually designed as a non-separable structure.

[0003] In existing technology, when the main gearbox malfunctions, the entire main gearbox needs to be disassembled from the helicopter fuselage and returned to the factory for inspection and repair. This process requires the complete disassembly of all related components, including the rotor blades, rotor hub, automatic swashplate, servo motors, and struts, before the main gearbox can be removed. These steps not only increase the complexity and workload of maintenance but also significantly extend the mean time to repair (MTTR) of the main gearbox, resulting in poor helicopter maintainability and impacting the helicopter's sortie rate and combat support capabilities. Summary of the Invention

[0004] In view of this, the present invention provides a main gearbox, a fixed support structure, and a rotorcraft to solve the problem in the prior art that the disassembly and maintenance of the main gearbox involves a large amount of disassembly work and a long average repair time, which leads to the difficulty of aircraft maintenance.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a main reducer, comprising: a rotor shaft structure and a reduction body; the rotor shaft structure includes a main shaft, a connecting housing, and a pressure ring assembly, the connecting housing being sleeved on the main shaft, the pressure ring assembly being disposed inside the main shaft, and the pressure ring assembly and the connecting housing being located at the same end of the main shaft; the reduction body includes a main housing, a planetary gear train assembly, and a fixed gear ring, the main housing and the connecting housing being detachably and fixedly connected to accommodate and fix the fixed gear ring; the outer periphery of the planetary gear train assembly is drively connected to the fixed gear ring, and a force transmission structure is provided at one end of the planetary gear train assembly near the main shaft, the force transmission structure cooperating with the pressure ring assembly and being detachably and fixedly connected.

[0007] It has the following advantages:

[0008] This invention provides a main gearbox where the rotor shaft structure and the gearbox body can be assembled and separated, facilitating independent disassembly without requiring the disassembly of the complex rotor shaft structure connected to the helicopter interface. This significantly reduces the disassembly and assembly steps required for maintenance, lowering the difficulty of troubleshooting and repair. The gearbox body is a fault-prone area, while the rotor shaft structure is highly integrated with interfaces such as the flight control system and electrical system. Through the split-structure design of this invention, in the event of a fault, only the gearbox body needs to be disassembled and returned to the factory for repair, without interfering with the rotor shaft structure. This greatly shortens the mean time to repair (MTTR) of the main gearbox and improves maintenance efficiency.

[0009] According to a first aspect of the present invention, the connecting housing includes a first housing and a second housing, the first housing is sleeved on the main shaft, one end of the first housing is connected to the main shaft through a bearing member, and the other end of the first housing is detachably connected to one end of the second housing.

[0010] According to a first aspect of the present invention, the pressure ring assembly includes a main body, a pressure plate fixedly connected to one side of the main body, and a first fastener fixedly disposed on the pressure plate. The main body is provided with a first connecting hole in the axial direction, and the pressure plate is provided with a second connecting hole. The second connecting hole, the first connecting hole and the first fastener are all located on the same axis.

[0011] The force transmission structure passes through the first connecting hole, and the second fastener passes through the first connecting hole and the second connecting hole, with one end extending to be threadedly connected to the first fastener, so as to fix the force transmission structure to the pressure ring assembly.

[0012] According to a first aspect of the present invention, the main body is provided with a plurality of third connecting holes, and the pressure plate is provided with a plurality of fourth connecting holes. The third connecting holes and the fourth connecting holes are coaxially arranged and are evenly spaced along the circumferential direction.

[0013] The force transmission structure has a fifth connecting hole, and a third fastener passes through the fifth connecting hole, the fourth connecting hole, and the third connecting hole to fix the force transmission structure and the pressure ring assembly.

[0014] According to a first aspect of the present invention, the spindle has an inner conical surface, and the main body has an outer conical surface that mates with the inner conical surface, so as to limit the pressure ring assembly to the spindle.

[0015] According to a first aspect of the present invention, the planetary gear train assembly includes a bearing housing, a planetary gear carrier, and planetary gears. The bearing housing, the second housing, and the first housing are detachably connected by a third fastener. The force transmission structure is connected to the pressure ring assembly to be adapted to mount the planetary gear carrier on the bearing housing. The planetary gears are disposed on the planetary gear carrier and their outer circumference is drivenly connected to the fixed gear ring.

[0016] According to a first aspect of the present invention, the rotor shaft structure further includes a spacer sleeve, the spacer sleeve being sleeved on the main shaft, the bearing housing abutting against the spacer sleeve, and the spacer sleeve being adapted to support the bearing housing.

[0017] Secondly, the present invention also provides a fixed support structure applied to the main reducer, comprising: an assembly fastener and an assembly pressure plate; the assembly fastener includes a main body portion, and a first support portion and a second support portion disposed on the main body portion, the first support portion being fixedly connected to a connecting housing via a first connector, such that the second support portion abuts against the spacer sleeve of the main reducer, and the second support portion and the main shaft clamp and fix the spacer sleeve; the assembly pressure plate is fixedly connected to the pressure ring assembly of the main reducer via a second connector, and one side of the assembly pressure plate abuts against the main body portion.

[0018] Thirdly, the present invention also provides a fixed support structure applied to the main reducer; comprising: a protective cover and a support pad; the outer periphery of the protective cover is connected to the main housing via a third connector to be adapted to fix and install a fixed gear ring, and the planetary gears and the sun gear are meshed with the fixed gear ring; the protective cover forms a shielding cavity to be adapted to shield the planetary gear train assembly on the main housing; the support pad is disposed inside the reducer body, the upper end of the support pad abuts against the upper end of the force transmission structure, and the lower end face abuts against the sun gear, so that the force transmission structure and the bearing seat clamp and fix the planetary gear carrier.

[0019] Fourthly, the present invention also provides a rotorcraft including the aforementioned main gearbox. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a cross-sectional view of a main reducer provided in some embodiments of the present invention;

[0022] Figure 2 A cross-sectional view of a planetary gear train assembly of a main reducer provided in some embodiments of the present invention;

[0023] Figure 3 A cross-sectional view of a pressure ring assembly of a main reducer provided in some embodiments of the present invention;

[0024] Figure 4 This is a cross-sectional view of a rotor shaft structure equipped with the fixed support structure of the second aspect in some embodiments of the present invention;

[0025] Figure 5 This is a cross-sectional view of a deceleration body equipped with a fixed support structure of the third aspect in some embodiments of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Rotor shaft structure; 11. Main shaft; 12. Connecting housing; 13. Pressure ring assembly; 14. Spacer sleeve; 121. First housing; 122. Second housing; 131. Main body; 132. Pressure plate; 133. First fastener; 2. Reduction body; 21. Main housing; 22. Planetary gear train assembly; 23. Fixed gear ring; 24. Force transmission structure; 221. Bearing seat; 222. Planetary gear carrier; 223. Planetary gear; 231. Sun gear; 3. Assembly fastener; 4. Assembly pressure plate; 5. Protective cover; 6. Support pad. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Reference Figure 1 As shown, in a first aspect of the present invention, the present invention provides a main reducer, comprising: a rotor shaft structure 1 and a reduction body 2; the rotor shaft structure 1 includes a main shaft 11, a connecting housing 12 and a pressure ring assembly 13, the connecting housing 12 being sleeved on the main shaft 11, the pressure ring assembly 13 being disposed inside the main shaft 11, and the pressure ring assembly 13 and the connecting housing 12 being disposed at the same end of the main shaft 11; the reduction body 2 includes a main housing 21, a planetary gear train assembly 22 and a fixed gear ring 23, the main housing 21 and the connecting housing 12 being detachably and fixedly connected to accommodate the fixed gear ring 23; the outer periphery of the planetary gear train assembly 22 is connected to the fixed gear ring 23 in a transmission manner, and a force transmission structure 24 is provided at one end of the planetary gear train assembly 22 near the main shaft 11, the force transmission structure 24 cooperating with the pressure ring assembly 13 and being detachably and fixedly connected.

[0033] Specifically, this invention provides a main gearbox where the rotor shaft structure 1 and the gearbox body 2 can be assembled and separated, facilitating independent disassembly without requiring disassembly of the rotor shaft structure 1, which has complex interfaces with the helicopter. This significantly reduces the disassembly and assembly steps required for maintenance, lowering the difficulty of troubleshooting and repair. The gearbox body 2 is a fault-prone area, while the rotor shaft structure 1 is highly integrated with interfaces such as the flight control system and electrical system. Through the split-structure design of this invention, in the event of a fault, only the gearbox body 2 needs to be disassembled and returned to the factory for repair, without interfering with the rotor shaft structure 1. This greatly shortens the mean time to repair (MTTR) of the main gearbox and improves maintenance efficiency.

[0034] Understandably, since the rotor shaft structure 1 and the reduction gear body 2 can be manufactured and assembled separately, they can be tested and calibrated separately at different production stages, which is beneficial to improving assembly accuracy and production yield. At the same time, this split structure facilitates standardized and serialized design, aiding in adaptation and upgrades between different models, and enhancing the versatility and engineering adaptability of the main reducer. In this invention, the planetary gear train assembly 22 is equipped with a force transmission structure 24 that cooperates with the pressure ring assembly 13, and is detachably connected to the rotor shaft main shaft 11. While ensuring good transmission efficiency, it also ensures the stability of force transmission and reliable positioning between modules, which is conducive to achieving a highly reliable power transmission path.

[0035] Reference Figure 1 As shown, in a first aspect embodiment of the present invention, the connecting housing 12 includes a first housing 121 and a second housing 122. The first housing 121 is sleeved on the main shaft 11. One end of the first housing 121 is connected to the main shaft 11 through a bearing component. The other end of the first housing 121 is detachably connected to one end of the second housing 122.

[0036] Specifically, the first housing 121 provides proximal support to the main shaft 11 via bearing components, ensuring clear radial and axial positioning of the main shaft 11 at the connecting housing 12, reducing the deflection and runout of the main shaft 11. The first housing 121 is fitted onto the main shaft 11 and pre-positioned via bearing components. The second housing 122 is then detachably connected to it, forming an assembly cycle of positioning followed by closure. This facilitates step-by-step measurement, step-by-step self-alignment, and preload control, improving assembly consistency and yield. The detachable connection between the first housing 121 and the second housing 122 allows for segmented opening of the housing ends during maintenance without completely disassembling the connecting housing 12. This facilitates inspection, lubrication, or replacement of bearing components, the end of the main shaft 11, and adjacent force transmission structures 24, further shortening the mean time to repair (MTTR) of the main reducer.

[0037] Reference Figure 3 As shown, in a first aspect embodiment of the present invention, the pressure ring assembly 13 includes a main body 131, a pressure plate 132 fixedly connected to one side of the main body 131, and a first fastener 133 fixedly disposed on the pressure plate 132. The main body 131 is provided with a first connecting hole in the axial direction, and the pressure plate 132 is provided with a second connecting hole. The second connecting hole, the first connecting hole and the first fastener 133 are all located on the same axis.

[0038] The force transmission structure 24 passes through the first connecting hole, and the second fastener passes through the first connecting hole and the second connecting hole, with one end extending to be threadedly connected to the first fastener 133, so as to fix the force transmission structure 24 to the pressure ring assembly 13.

[0039] Specifically, the second fastener forms a force-bearing closed loop with the first fastener 133 fixed on the pressure plate 132 through the first and second connecting holes, so that the pressure plate 132 generates a controllable end face clamping force on the main body 131, thereby achieving reliable clamping and positioning of the force transmission structure 24, avoiding loosening and micro-movement under impact load and variable load conditions. The first connecting hole, the second connecting hole and the first fastener 133 are arranged coaxially to ensure that the second fastener and the force transmission structure 24 automatically find the center during assembly, shorten the critical tolerance chain, reduce assembly eccentricity and tilt angle errors, and help maintain the coaxial meshing and stable operation of the transmission components on the spindle 11 side.

[0040] The first fastener 133 is fixed on the pressure plate 132 and serves as the internal thread, avoiding the problems of stripping, scoring, and stress concentration caused by directly tapping the main body 131. When the thread wears, only the first fastener 133 needs to be replaced to restore the connection strength, resulting in high maintenance economy. The threaded connection is located on the coaxial force path, and the preload can be precisely set according to the torque-preload relationship, so that the working load is lower than the preload threshold. Combined with the surface pressure friction effect of the pressure plate 132, it significantly suppresses loosening and relative displacement under vibration environment, reducing the risk of abrasive wear and fretting corrosion. The first fastener 133 is fixed on the pressure plate 132, eliminating the need to reverse hold on the back of the main body 131 or find the nut position. During maintenance, only the second fastener needs to be operated to tighten or loosen, which is suitable for confined spaces such as the inner cavity of the spindle 11, improving assembly efficiency and further shortening MTTR.

[0041] In a first aspect of the present invention, the main body 131 is provided with a plurality of third connecting holes, and the pressure plate 132 is provided with a plurality of fourth connecting holes. The third connecting holes and the fourth connecting holes are coaxially arranged and are evenly spaced along the circumferential direction.

[0042] The force transmission structure 24 has a fifth connecting hole, and a third fastener passes through the fifth connecting hole, the fourth connecting hole, and the third connecting hole to fix the force transmission structure 24 and the pressure ring assembly 13.

[0043] Specifically, multiple third / fourth connecting holes are arranged at equal intervals along the circumference to achieve multi-point synchronous pressing of the pressure plate 132, the main body 131 and the force transmission structure 24, which significantly reduces local surface pressure peaks and warping deformation, and improves the fit of the connecting surfaces and the consistency of repeated assembly.

[0044] In a first aspect of the present invention, a clearance space is formed between the pressure plate 132 and the main body 131. Under pre-tightening and service deformation conditions, the pressure plate 132 does not make additional contact with the main body 131, preventing the introduction of additional loads and over-constraints in assembly due to non-designed contact points, and ensuring that the force flow is transmitted only through the set fasteners and the pressing surface. The clearance space makes the force boundary of the pressing surface clear, reducing the pre-tightening force attenuation and torque bypass caused by accidental surface collisions, maintaining the target pre-tightening level of the second and third fasteners for a long time, and improving the connection reliability.

[0045] In a first aspect of the present invention, the spindle 11 is provided with an inner conical surface, and the main body 131 is provided with an outer conical surface that mates with the inner conical surface, so as to limit the pressure ring assembly 13 to the spindle 11.

[0046] Specifically, the inner and outer conical surfaces are rotationally symmetrically fitted, generating a self-guiding effect during assembly. This allows the pressure ring assembly 13 to automatically align itself during axial insertion, significantly reducing eccentricity and tilting errors. The conical surface clamping creates axial force and normal preload, resulting in geometric and frictional self-locking. This effectively restricts the axial position of the pressure ring assembly 13 under variable load and vibration environments, suppressing movement and springback. The conical surface fit forms an effective friction ring in the circumferential direction, sharing the counter-torque and impact load from the force transmission structure 24, reducing the shear and bending burden on the central fastener, and forming a force-bearing system that combines conical surface friction and pre-tightening.

[0047] Understandably, compared to end face stops or local shoulders, conical surfaces provide surface contact, and the contact area increases with the preload, which helps to disperse contact compressive stress and edge effects, improving the fatigue life and pitting resistance of the connection pair. Conical surface fits exhibit self-friction-increasing characteristics under micro-amplitude vibrations. Combined with multi-bolt circumferential preload, this significantly reduces interface fretting and thread loosening, maintaining long-term stable preload and positioning accuracy.

[0048] The limit / positioning function is built into the conical surface of the spindle 11 inner cavity, eliminating the need for an additional external flange or additional anti-reverse structure, which is beneficial for axial / radial space convergence and quality control.

[0049] Reference Figure 2 As shown, in a first aspect embodiment of the present invention, the planetary gear train assembly 22 includes a bearing housing 221, a planetary gear carrier 222, and a planetary gear 223. The bearing housing 221, the second housing 122, and the first housing 121 are detachably connected by a third fastener. The force transmission structure 24 is connected to the pressure ring assembly 13 to be adapted to mount the planetary gear carrier 222 on the bearing housing 221. The planetary gear 223 is disposed on the planetary gear carrier 222 and its outer periphery is connected to the fixed gear ring 23 for transmission.

[0050] Specifically, the planetary gear carrier 222 is independently supported by the bearing housing 221, which is then connected to the gearbox via a third fastener. This allows the planetary gear train and bearing housing 221 to be pre-assembled as a whole module, with tooth patterns measured, pre-tightened, and bench-running completed, enabling rapid integration into the main reducer body and shortening the overall assembly cycle. The planetary gear carrier 222 is positioned using the bearing housing 221 as a reference bearing, avoiding cumulative errors caused by direct positioning across a large-span gearbox. Combined with the segmented gearbox design, key coaxiality and center distance are closed by adjacent parts, improving meshing accuracy.

[0051] Understandably, the connection between the bearing housing 221 and the casing can be disassembled by removing the third fastener, enabling rapid overall replacement or repair of the planetary gear train assembly 22; decoupling from the rotor shaft structure 1 significantly reduces on-site disassembly and alignment work. The force transmission structure 24 and the pressure ring assembly 13 provide clear axial preload and end face positioning for the planetary gear carrier 222, which, in conjunction with the radial / end face reference of the bearing housing 221, facilitates process control according to torque and preload specifications; the positioning repeatability after disassembly and assembly is high, reducing adjustment time after reassembly.

[0052] The load of the planetary gear carrier 222 enters the casing via the nearest loop through the bearing housing 221, reducing the additional load on the main shaft 11 and the far-end support; the bearing housing 221 facilitates the arrangement of suitable bearing types and spans, improves the matching of bending and torsional stiffness, reduces bearing edge stress and temperature rise, and extends service life.

[0053] In a first aspect of the present invention, the rotor shaft structure 1 further includes a spacer sleeve 14, which is sleeved on the main shaft 11. The bearing seat 221 abuts against the spacer sleeve 14, and the spacer sleeve 14 is adapted to support the bearing seat 221.

[0054] Specifically, the spacer sleeve 14, acting as a rigid padding element on the spindle 11, abuts against the end face of the bearing housing 221. Loads are transmitted to the spindle 11 via the spacer sleeve 14 through the nearest loop, reducing the cantilever length and end warping of the bearing housing 221, significantly improving bending and torsional stiffness, and reducing center distance drift and tilting error at the planetary meshing point. By selecting / grinding spacer sleeves 14 of different thicknesses, machining and assembly tolerances can be compensated, enabling minute adjustments to the position of the bearing housing 221. Key dimensions are closed by short tolerance chains, improving the consistency and interchangeability of repeated assemblies.

[0055] Understandably, the spacer sleeve 14 provides stable end face support, reduces local stress and edge effects on the pressure surface of the bearing housing 221, avoids bearing misalignment, raceway pitting, and early fatigue due to reference drift, and extends the life of the bearing and gear pair. The material and structure of the spacer sleeve 14 can be designed to match the coefficient of thermal expansion of the spindle 11 / bearing housing 221. Axial dimensional drift during thermal cycling is predictable and controllable, reducing preload drift with temperature fluctuations and maintaining stable positioning.

[0056] The spacer sleeve 14 is coaxially fitted with the main shaft 11, providing auxiliary coaxial guidance near the support, reducing the eccentricity and tilt of the bearing housing 221 relative to the main shaft 11, and ensuring the coaxial meshing of the planetary carrier and the fixed gear ring 23. The standardized spacer sleeve 14 enables rapid adaptation to different models or different meshing adjustment requirements, reduces repeated processing of the casing and bearing housing 221, and balances manufacturing cost and assembly flexibility.

[0057] Reference Figure 4 As shown, in a second aspect of the invention, the invention also provides a fixed support structure applied to a main reducer, comprising: an assembly fastener 3 and an assembly pressure plate 4; the assembly fastener 3 includes a main body portion, and a first support portion and a second support portion disposed on the main body portion, the first support portion being fixedly connected to the connecting housing 12 via a first connector, such that the second support portion abuts against the spacer sleeve 14 of the main reducer, and the second support portion and the main shaft 11 clamp and fix the spacer sleeve 14; the assembly pressure plate 4 is fixedly connected to the pressure ring assembly 13 of the main reducer via a second connector, and one side of the assembly pressure plate 4 abuts against the main body portion.

[0058] Specifically, when the main reducer body is disassembled / disassembled, the double-support point support and clamping formed by the first support part and the second support part ensures that the rotor shaft assembly maintains its shape and pre-tightness as a whole, and does not fall apart or become misaligned due to the loss of the casing constraint.

[0059] Understandably, the fixed support structure is equivalent to the tooling provided with the parts: on-site, only the first and second connecting parts need to be loosened / tightened to complete the assembly and disassembly of the main reducer body or planetary module without removing the rotor shaft assembly, making replacement and repair more efficient. The second support and the clamping of the spacer sleeve 14 by the main shaft 11 provide clear end face support, preventing bearing roller misalignment, raceway pitting, or edge stress peaks caused by self-weight during disassembly / transportation, thereby improving bearing life and reliability.

[0060] The main body of the assembly fastener 3 can adopt a stiffener / window structure and standardize the specifications of the first / second connecting parts; weight reduction is achieved while meeting rigidity requirements, and it is convenient for cross-model reuse and serialization. By setting a shallow groove or chamfer in the contact area of ​​the second support / spacer sleeve 14, oil return can be guided and oil stains can be reduced during assembly and disassembly; it is also easier to carry out spray cleaning and visual inspection in the supported state to ensure the cleanliness of the bearing and tapered surface.

[0061] Reference Figure 5As shown, in a third aspect of the invention, the invention also provides a fixed support structure applied to a main reducer; comprising: a protective cover 5 and a support pad 6; the outer periphery of the protective cover 5 is connected to the main housing 21 via a third connector to be adapted to fix the fixed gear ring 23, and the planetary gear 223 and the sun gear 231 are meshed with the fixed gear ring 23; the protective cover 5 forms a shielding cavity to be adapted to shield the planetary gear train assembly 22 on the main housing 21; the support pad 6 is disposed in the reducer body 2, the upper end of the support pad 6 abuts against the upper end of the force transmission structure 24, and the lower end face abuts against the sun gear 231, so that the force transmission structure 24 and the bearing seat 221 clamp and fix the planetary gear carrier 222.

[0062] Specifically, the protective cover 5 and the main housing 21 form a closed shielding cavity, effectively preventing FOD such as screws, debris, and dust from entering the planetary gear train area during transportation / storage / ground testing, thus avoiding scratches or jamming of the gear teeth and bearing raceways. The protective cover 5, via the third connector, forms opposing clamping surfaces with the main housing 21, providing clear axial and circumferential positioning for fixing the gear ring 23, reducing gear ring runout and end face warping, and improving the meshing consistency and tooth flank clearance stability of the planetary gear ring.

[0063] Understandably, the support pad 6 is made of high-damping materials such as nylon, which has strong energy absorption and peak-shaving and valley-filling capabilities, reducing the impact and fretting of transport vibration on the tooth surface and bearing rolling elements, and suppressing raceway micro-pitting and meshing edge extrusion; the lower end of the support pad 6 is in close contact with the sun gear 231 for support, limiting its displacement and sway in non-working state, and avoiding knocking wear at the connection between the central gear shaft system and the key / spline.

[0064] The shielding cavity suppresses oil mist escape and external dust intrusion, keeping the gear surface clean. It also shields against convection / splash noise and external sound radiation, reducing noise and potential pollution during transport. The protective cover 5 uses a third connector for quick installation and removal, and the support pad 6 is an included tooling component; its installation / removal does not affect the working configuration. When replacing or repairing the main body on-site, there is no need to move the rotor shaft interface, further shortening the mean time to repair (MTTR).

[0065] The fixed gear ring 23 is clamped and closed by the protective cover 5 and the main housing 21 on both sides. The key dimensions are closed by adjacent parts to reduce cumulative errors. The upper and lower end faces of the support pad 6 are clearly aligned, and the positioning state can be repeatedly reproduced after disassembly and assembly. Under abnormal loads such as handling impact / drop, the support pad 6 provides a load-bearing channel to share transient forces and reduce the peak stress on the fasteners and tooth surfaces. The protective cover 5 serves as a buffer layer for the outer shell, improving the overall impact resistance.

[0066] The support pad 6 can be selected with different hardness / thickness nylon (or similar engineering plastics) specifications according to quality level and transport spectrum, taking into account both support rigidity and cushioning performance, which facilitates cross-model platform application and inventory management. During long-term storage, the support pad 6 bears and distributes the self-weight of the central component and environmental micro-vibrations, maintaining the relative position and clearance of the internal transmission components without additional processing, reducing damage during storage.

[0067] In some embodiments of the present invention, the installation of the rotor shaft assembly and the main gearbox body of the main gearbox on a helicopter includes the following steps:

[0068] Step S1: Install the rotor shaft assembly onto the helicopter, including the struts, swashplate, servo, rotor hub, and rotor blades;

[0069] Step S2: Remove the mounting fastener 3 and mounting pressure plate 4 from the rotor shaft assembly;

[0070] Step S3: Remove the protective cover 5 from the deceleration body 2;

[0071] Step S4: Extract the planetary gear train assembly 22 and the support pad 6 from the deceleration body 2;

[0072] Step S5: Install the planetary gear train assembly 22 onto the rotor shaft assembly, with the internal splines of the planetary gear carrier 222 engaging with the external splines of the rotor shaft; after fixing the first housing 121, the second housing 122, and the bearing housing 221, connect the planetary gear train assembly 22 to the second housing 122. Thread the force transmission structure 24 to the pressure ring assembly 13, ensuring that the outer conical surface of the pressure ring assembly 13 is tightly fitted to the inner conical surface of the rotor shaft, and that the surface of the force transmission structure 24 is tightly fitted to the surface of the planetary gear carrier 222, ensuring the rotor shaft axis is centered. This allows the rotor shaft load to be transmitted to the planetary gear carrier 222 via the force transmission structure 24, and then to the connecting housing 12 via the bearing and bearing housing 221.

[0073] Step S6: Install the remaining part of the reduction body 2 onto the rotor shaft assembly, and connect the first casing 121, the second casing 122 and the main casing 21 together. During the installation process, it is necessary to ensure that the sun gear 231 is properly meshed with the planetary gear 223 and the self-aligning roller bearing assembly.

[0074] Fourthly, the present invention also provides a rotorcraft including a main gearbox.

[0075] Specifically, the split main gearbox allows the easily faulty gearbox body 2 to be replaced separately, while the rotor shaft structure 1 remains stationary on the aircraft, significantly shortening the mean time to repair (MTTR), reducing ground downtime, and improving the aircraft's sortie rate and mission completion rate; modular replacement reduces the frequency of overhauls and return-to-factory time; the disassembly and assembly steps and alignment procedures are simplified, reducing manpower and spare parts usage; combined with the increase in lifespan and the reduction in failure rate, the total life cycle maintenance cost is significantly reduced.

[0076] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A main reducer, characterized in that, include: The rotor shaft structure (1) includes a main shaft (11), a connecting box (12) and a pressure ring assembly (13). The connecting box (12) is sleeved on the main shaft (11), and the pressure ring assembly (13) is disposed inside the main shaft (11). The pressure ring assembly (13) and the connecting box (12) are located at the same end of the main shaft (11). The reduction body (2) includes a main housing (21), a planetary gear train assembly (22), and a fixed gear ring (23). The main housing (21) and the connecting housing (12) are detachably and fixedly connected to clamp and fix the fixed gear ring (23). The outer periphery of the planetary gear train assembly (22) is connected to the fixed gear ring (23) for transmission. A force transmission structure (24) is provided at one end of the planetary gear train assembly (22) near the main shaft (11). The force transmission structure (24) is connected to the pressure ring assembly. The pressure ring assembly (13) is fitted and detachably fixedly connected to the main body (131), the pressure plate (132) fixedly connected to one side of the main body (131), and the first fastener (133) fixedly disposed on the pressure plate (132). The main body (131) has a first connecting hole in the axial direction, and the pressure plate (132) has a second connecting hole. The second connecting hole, the first connecting hole and the first fastener (133) are all located on the same axis. The force transmission structure (24) passes through the first connecting hole, and the second fastener passes through the first connecting hole and the second connecting hole, with one end extending to be threadedly connected to the first fastener (133) to fix the force transmission structure (24) to the pressure ring assembly (13).

2. The main reducer according to claim 1, characterized in that, The connecting housing (12) includes a first housing (121) and a second housing (122). The first housing (121) is sleeved on the main shaft (11). One end of the first housing (121) is connected to the main shaft (11) through a bearing component. The other end of the first housing (121) is detachably connected to one end of the second housing (122).

3. The main reducer according to claim 1, characterized in that, The main body (131) has a plurality of third connecting holes, and the pressure plate (132) has a plurality of fourth connecting holes. The third connecting holes and the fourth connecting holes are coaxially arranged and are evenly spaced along the circumference. The force transmission structure (24) has a fifth connecting hole, and a third fastener passes through the fifth connecting hole, the fourth connecting hole and the third connecting hole to fix the force transmission structure (24) and the pressure ring assembly (13).

4. The main reducer according to claim 1 or 3, characterized in that, The spindle (11) has an inner conical surface, and the main body (131) has an outer conical surface that mates with the inner conical surface, so as to limit the pressure ring assembly (13) to the spindle (11).

5. The main reducer according to claim 2, characterized in that, The planetary gear train assembly (22) includes a bearing housing (221), a planetary gear carrier (222), and a planetary gear (223). The bearing housing (221), the second housing (122), and the first housing (121) are detachably connected by a third fastener. The force transmission structure (24) is connected to the pressure ring assembly (13) to be adapted to mount the planetary gear carrier (222) on the bearing housing (221). The planetary gear (223) is disposed on the planetary gear carrier (222) and its outer periphery is connected to the fixed gear ring (23) for transmission.

6. The main reducer according to claim 5, characterized in that, The rotor shaft structure (1) also includes a spacer sleeve (14), which is sleeved on the main shaft (11), and the bearing seat (221) abuts against the spacer sleeve (14). The spacer sleeve (14) is adapted to support the bearing seat (221).

7. A fixed support structure, applied to the main reducer according to any one of claims 1-6; characterized in that, include: Assembly fastener (3) includes a main body and a first support and a second support provided on the main body. The first support is fixedly connected to the connecting box (12) by a first connector, so that the second support abuts against the spacer sleeve (14) of the main reducer. The second support and the main shaft (11) clamp and fix the spacer sleeve (14). The assembly pressure plate (4) is fixedly connected to the pressure ring assembly (13) of the main reducer through the second connector, and one side of the assembly pressure plate (4) abuts against the main body.

8. A fixed support structure, applied to the main reducer according to any one of claims 1-6; characterized in that, include: A protective cover (5) is connected to the main housing (21) via a third connector to securely mount a fixed gear ring (23). Planetary gears (223) and sun gears (231) mesh with the fixed gear ring (23). The protective cover (5) forms a shielding cavity to shield the planetary gear train assembly (22) on the main housing (21). Support pad (6) is located inside the deceleration body (2). The upper end of the support pad (6) abuts against the upper end of the force transmission structure (24), and the lower end face abuts against the sun gear (231), so that the force transmission structure (24) and the bearing seat (221) clamp and fix the planetary gear carrier (222).

9. A rotary-wing aircraft, characterized in that, It includes the main reducer as described in any one of claims 1-6.

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