Transmission structure of helicopter rotor drum

Abstract

The application discloses a transmission structure of a helicopter paddle drum and relates to the technical field of helicopters, and solves the problem of low safety and easy fatigue fracture of a seesaw type rotor caused by the fact that driving force is completely borne by a horizontal through bearing, and the technical scheme is as follows: the transmission structure comprises balls which are coaxial and detachably connected to the outer walls of a first main shaft and a second main shaft; a plurality of grooves are formed in the outer wall of each ball in the circumferential direction, and the length direction of each groove is distributed along the outer spherical surface arc of the ball; a plurality of rolling balls are respectively and rollingly connected in the grooves; a connecting ring is connected to two blades in the same blade group; a placing disc is connected to the inside of the connecting ring, and the placing disc has an inner cavity for accommodating the corresponding ball; a retainer is sleeved on the outside of each ball, and the retainer is provided with a placing hole for accommodating the rolling ball; and the inner wall of the placing disc is provided with a spherical surface which is matched with the outer surface of the corresponding ball, and the spherical surface is provided with an embedding groove for embedding one end of the rolling ball.

Description

Technical Field

[0001] This invention relates to the field of helicopter technology, specifically to a transmission structure for a helicopter rotor drum. Background Technology

[0002] like Figure 9 and Figure 10 As shown, the seesaw rotor is a common helicopter main rotor configuration. Its typical feature is that two symmetrical blades are connected by a hub housing 2, which passes through a rotating main shaft. A horizontal through shaft 21 (i.e., the seesaw shaft) is fixedly connected to the main shaft, and the horizontal through shaft 21 is hinged to the hub housing 2. This horizontal through shaft allows the two blades to rotate as a whole.

[0003] However, the existing seesaw rotor hub structure has significant stress defects. Specifically, during the high-speed rotation of the main shaft, the main shaft drives the hub housing to rotate through the horizontal through shaft, which in turn drives the blades to rotate. The driving force is entirely borne by the horizontal through shaft, which means that once the shaft cracks or corrodes, a catastrophic hub breakage accident may occur. Summary of the Invention

[0004] The purpose of this invention is to provide a transmission structure for a helicopter rotor drum, which solves the problems of low safety and easy fatigue fracture caused by the fact that the driving force of the existing seesaw rotor is entirely borne by the horizontal through shaft.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a transmission structure for a helicopter rotor drum, comprising a first main shaft and a second main shaft that are coaxially distributed and rotate in opposite directions, wherein the second main shaft is sleeved inside the first main shaft; All blade groups are set on the first and second main shafts, and each blade group contains two blades. Spheres that are coaxially and detachably connected to the outer walls of the first and second main shafts; Several grooves are formed on the outer wall of each sphere along the circumference, and the length direction of each groove is distributed along the curvature of the outer spherical surface of the sphere. The balls are connected to each groove in a rolling motion. A connecting ring that connects two blades in the same blade group; A placement tray detachably connected to the inside of the connecting ring, the placement tray having an inner cavity for accommodating a corresponding sphere; A retainer fitted around each ball, the retainer having placement holes for receiving the balls; The inner wall of the placement tray is configured as a spherical surface that matches the outer surface of the corresponding sphere, and an embedding groove is provided on the spherical surface for one end of the ball to be embedded.

[0006] By adopting the above technical solution, when the helicopter power system drives the first main shaft and the second main shaft to rotate in opposite directions, the first main shaft drives the detachably connected spheres on its outer wall to rotate synchronously, and the second main shaft drives the spheres on its outer wall to rotate synchronously, with the two spheres rotating in opposite directions. Ball rolling: When the ball rotates, some of the balls in the grooves on its outer wall are embedded in the placement holes of the cage, and the other part is embedded in the insertion grooves on the inner wall of the placement disk, thus forming a rolling friction pair between the ball, the cage, and the placement disk. Movement of the cage and the placement disk: Since the balls are simultaneously constrained in the grooves of the ball and the insertion grooves of the placement disk, when the ball rotates, the balls drive the cage to move accordingly, and transmit the rotational power to the placement disk through the cage. The placement disk and the connecting ring are detachably fixed, and the connecting ring is fixedly connected to the two blades in the same group. The placement disk drives the connecting ring to rotate, thereby causing the two blades in the same blade group to rotate synchronously. At the same time, since the first main shaft and the second main shaft rotate in opposite directions, the corresponding two groups of blades also rotate in opposite directions, realizing the torque balance and lift generation of the coaxial dual rotor. When the connecting ring and the placement plate can tilt and swing relative to the ball, the ball rolls between the arc groove and the insertion groove, and the cage adapts its position accordingly, thereby allowing the blade to generate the required pitch angle relative to the main shaft. The driving force is no longer entirely borne by a single horizontal through shaft, but is transmitted to the blades through multiple paths such as balls, rollers, cages, and mounting discs. Even if a ball or cage has a local crack or corrosion, the remaining rollers and grooves can still maintain some transmission capacity, reducing the risk of hub disintegration due to single-point failure.

[0007] Preferably, the first spindle and the second spindle are each provided with a plurality of limiting teeth on the outer wall of the corresponding sphere in the circumferential direction, and the inner wall of the sphere is provided with a locking tooth that can be inserted between two adjacent limiting teeth. The first spindle and the second spindle are each provided with a limiting member to restrict the sphere from sliding along the axis of the first spindle or the second spindle.

[0008] Preferably, the limiting member includes a lower chuck sleeved on the outer wall of the first spindle and the second spindle. The lower chuck is located below the ball. The inner wall of the lower chuck is provided with a lower stop tooth that inserts between two adjacent limiting teeth. The outer wall of the first spindle and the second spindle is provided with a first stepped surface that supports the lower end of each lower stop tooth. The upper end of the lower chuck passes through the placement plate and is supported at the lower end of the ball. The first spindle and the second spindle are provided with a clamping member above the ball to press the ball against the upper surface of the lower chuck.

[0009] Preferably, the clamping component includes an upper pressure plate sleeved on the outer wall of the first spindle and the second spindle. The inner wall of the upper pressure plate is provided with an upper stop tooth that inserts between two adjacent limit teeth. The upper end of the upper stop tooth is higher than the upper end of the limit tooth. A locking plate located above the upper pressure plate is sleeved on the outer wall of the first spindle and the second spindle. The inner wall of the locking plate is threadedly connected to the outer wall of the first spindle and the second spindle.

[0010] Preferably, the outer wall of the lower chuck is tapered, with the smaller end of the outer wall entering the placement tray, and the inner wall of the placement tray that abuts against the outer wall of the lower chuck is a conical surface that mates with the tapered shape.

[0011] Preferably, after the locking disc and the upper pressure disc come into contact, the locking disc and the upper pressure disc are connected by a number of locking screws.

[0012] Preferably, the upper end of the placement tray is provided with a connecting plate extending to the upper end face of the connecting ring, and the connecting plate and the connecting ring are connected by a number of fastening screws.

[0013] Preferably, the inner wall of the connecting plate and the inner wall of the placement plate are integrally formed and are both spherical surfaces that cooperate with the ball. The height of the connecting plate is higher than the center of the ball. The retainer is limited within the inner wall of the connecting plate. The upper end of the embedding groove extends out of the upper surface of the connecting plate.

[0014] Preferably, each sphere has 4 to 12 grooves, and each groove contains a corresponding ball bearing.

[0015] Preferably, the lower outer wall of the sphere is provided with a third step surface distributed in an annular pattern, and the lower inner wall of the placement tray is provided with a fourth step surface that contacts the third step surface. Both the third and fourth step surfaces have gaps with the lower end of the retainer, and the sum of the widths of the third and fourth step surfaces is the thickness of the retainer.

[0016] The beneficial effects of this invention are as follows: The driving force is no longer entirely borne by a single horizontal through shaft, but is transmitted to the blades through multiple paths such as balls, rollers, cages, and mounting discs. Even if a ball or cage has a local crack or corrosion, the remaining rollers and grooves can still maintain part of the transmission capacity, reducing the risk of hub disintegration due to single-point failure. The rolling contact between the balls and the arc-shaped groove disperses the torque and centrifugal force transmitted by the spindle to multiple balls and the embedded groove, reducing the combined stress on the connection interface between the balls and the spindle and extending fatigue life. Multiple balls work independently, so even if one ball fails, the remaining balls can still maintain transmission and positioning functions, providing pilots with time to handle emergency landings and improving flight safety. The balls roll purely within the arc-shaped grooves, which significantly reduces friction loss, heat generation, and wear compared to sliding friction or mechanical hinges, resulting in smoother and more efficient transmission. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of this embodiment; Figure 2 This is a schematic diagram illustrating the structure of the first and second spindles in this embodiment; Figure 3 This is a structural schematic diagram illustrating the first main shaft in this embodiment; Figure 4 for Figure 3 Enlarged structural diagram of section A in the middle; Figure 5 This is a schematic diagram illustrating the structure for placing the tray in this embodiment; Figure 6 This is a schematic diagram illustrating the structure of a sphere in this embodiment; Figure 7 This is a schematic diagram illustrating the structure of the connecting ring in this embodiment; Figure 8 This is a schematic diagram illustrating the structure of the lower chuck in this embodiment; Figure 9 A schematic diagram of an existing seesaw-type rotor structure; Figure 10 This is a schematic diagram of the horizontal through shaft in an existing seesaw-type rotor.

[0019] Explanation of reference numerals in the attached figures: In the diagram: 1. First main shaft; 11. Second main shaft; 12. Blade; 13. Sphere; 131. Groove; 132. Ball bearing; 133. Third stepped surface; 14. Connecting ring; 141. Through hole; 15. Placement plate; 151. Spherical surface; 152. Embedded groove; 16. Cage; 161. Placement hole; 17. Housing; 171. Upper end face gear; 172. Lower end face gear; 173. Horizontal rod; 174. Cylindrical gear; 175. Driven pulley; 18. Limiting tooth; 181. Clamping tooth; 182. Lower chuck; 183. Lower stop tooth; 184. First stepped surface; 185. Upper pressure plate; 186. Locking plate; 187. Conical surface; 188. Connecting plate; 19. Fourth stepped surface; 2. Hub housing; 21. Horizontal through shaft. Detailed Implementation

[0020] 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, and 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.

[0021] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; 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, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0022] A transmission structure for a helicopter rotor drum, such as Figure 1-8 It includes a first main shaft 1 and a second main shaft 11 that are coaxially distributed and rotate in opposite directions, with the second main shaft 11 sleeved inside the first main shaft 1; The blade groups are all set on the first main shaft 1 and the second main shaft 11. Each blade group includes two blades 12, which are distributed on opposite outer walls of the first main shaft 1 or the second main shaft 11. Spheres 13 are coaxially and detachably connected to the outer walls of the first main shaft 1 and the second main shaft 11. Several grooves 131 are provided on the outer wall of each sphere 13 along the circumferential direction. The length direction of each groove 131 is distributed along the arc of the outer spherical surface 151 of the sphere 13. Each groove 131 is distributed at equal angles on the outer wall of the sphere 13 along the arc of the sphere 13. The balls 132 are respectively connected to the grooves 131 in a rolling manner; A connecting ring 14 that connects two blades 12 in the same blade group; A placement plate 15 is detachably connected to the inside of the connecting ring 14. The placement plate 15 has an inner cavity to accommodate the corresponding ball 13. The placement plate 15 is fitted onto the outer wall of the first spindle 1 or the second spindle 11. The cage 16, fitted around each ball 13, is an integral ring structure. The cage 16 has placement holes 161 for accommodating the balls 132. The width of the cage 16 is less than the length of the groove 131. The placement holes 161 are rectangular. The balls 132 have a clearance fit with the wall of the rectangular hole in the width direction and a sliding fit with the wall of the rectangular hole in the length direction. The width direction of the rectangular hole is consistent with the extension direction of the groove 131. The clearance fit allows the balls 132 to roll smoothly along the direction of the groove 131, while the sliding fit with the wall of the rectangular hole in the length direction provides the following advantages: The balls 132 can slide circumferentially within the length of the rectangular hole, absorbing the impact load generated by the oscillation of the blade 12 and reducing structural damage caused by rigid transmission; Anti-jamming: The sliding fit prevents the balls from being jammed circumferentially, ensuring smooth transmission and improving reliability; Motion decoupling: Rolling along the groove direction and sliding circumferentially, the two motion modes do not interfere with each other, achieving the integration of load-bearing, transmission, and buffering functions. The inner wall of the placement plate 15 is set as a spherical surface 151 that matches the outer surface of the corresponding ball 13. An embedding groove 152 is provided on the spherical surface 151 for one end of the ball 132 to be embedded. A part of the ball 132 is located in the groove 131 and the other part is located in the embedding groove 152. At this time, the ball 132 is simultaneously located in the corresponding groove 131 and the embedding groove 152.

[0023] The transmission ball structure in the helicopter rotor drum transmission structure includes the connection structure between the aforementioned ball 13, groove 131, and cage 16.

[0024] like Figure 1-8When the helicopter power system drives the first main shaft 1 and the second main shaft 11 to rotate in opposite directions, the first main shaft 1 drives the detachably connected ball 13 on its outer wall to rotate synchronously, and the second main shaft 11 drives the ball 13 on its outer wall to rotate synchronously, with the two balls 13 rotating in opposite directions. The helicopter power system includes an electric motor mounted on the helicopter and a housing 17 mounted on the upper end face of the helicopter. The first main shaft 1 is rotatably connected inside the housing 17, which has a cavity. The lower end of the second main shaft 11 extends out of the lower end of the first main shaft 1 and is located inside the housing 17. One end of the first main shaft 1 and the second main shaft 11 inside the housing 17 are coaxially fixedly connected to an upper end face gear 171 and a lower end face gear 172. The upper end face gear 171 is located above the lower end face gear 172, and there is a gap between them. A horizontal rod 173 is rotatably connected to the housing 17. A cylindrical gear 174, which meshes with both the upper end face gear 171 and the lower end face gear 172, is coaxially fixed at one end of the housing 17. At this time, the cylindrical gear 174 is located between the upper end face gear 171 and the lower end face gear 172. A driven pulley 175 is coaxially fixedly connected to one end of the horizontal rod 173 extending out of the housing 17. A driving pulley is coaxially fixedly connected to the rotating shaft of the motor. The driving pulley and the driven pulley 175 are connected by an annular belt (not shown in the figure). When the motor drives the driving pulley to rotate, the driven pulley 175 is driven to rotate through the annular belt, which in turn drives the horizontal rod 173 to rotate. The rotation of the horizontal rod 173 drives the cylindrical gear 174 to rotate, thereby driving the upper end face gear 171 and the lower end face gear 172 to rotate in opposite directions, so that the first main shaft 1 and the second main shaft 11 rotate coaxially in opposite directions.

[0025] like Figure 1-8 The rolling of ball 132: When ball 13 rotates, part of the ball 132 in the groove 131 of its outer wall is embedded in the placement hole 161 of cage 16, and the other part is embedded in the insertion groove 152 of the inner wall of placement disk 15, thereby forming a rolling friction pair between ball 13, cage 16 and placement disk 15. Movement of cage 16 and placement disk 15: Since the ball 132 is simultaneously constrained in the groove 131 of ball 13 and the insertion groove 152 of placement disk 15, when ball 13 rotates, the ball 132... 2. The drive cage 16 moves accordingly and transmits rotational power to the placement plate 15 through the cage 16. The placement plate 15 is detachably fixed to the connecting ring 14, and the connecting ring 14 is fixedly connected to the two blades 12 in the same group. The placement plate 15 drives the connecting ring 14 to rotate, thereby making the two blades 12 in the same blade group rotate synchronously. At the same time, since the first main shaft 1 and the second main shaft 11 rotate in opposite directions, the two corresponding sets of blades 12 also rotate in opposite directions, realizing the torque balance and lift generation of the coaxial dual rotor.

[0026] like Figure 1-8When the connecting ring 14 together with the placement plate 15 can tilt and swing relative to the ball 13, the ball 132 rolls between the arc groove 131 and the embedded groove 152, and the cage 16 adaptively adjusts its position accordingly, thereby allowing the blade 12 to generate the required pitch angle relative to the main shaft.

[0027] like Figure 1-8 The driving force is no longer entirely borne by a single horizontal shaft 21, but is transmitted to the blade 12 through multiple paths via the ball 13, ball 132, cage 16, and placement disk 15. Even if a ball 13 or cage 16 has a local crack or corrosion, the remaining ball 132 and groove 131 can still maintain part of the transmission capacity, reducing the risk of hub disintegration due to single-point failure.

[0028] like Figure 1-8 The rolling contact between the ball bearings 132 and the arc-shaped groove 131 disperses the torque and centrifugal force transmitted by the spindle to multiple balls 132 and the embedded groove 152, reducing the combined stress on the connection interface between the ball 13 and the spindle and extending fatigue life. Multiple balls 132 work independently, and even if individual balls 132 fail, the remaining balls 132 can still maintain transmission and positioning functions, providing pilots with time for emergency landing and improving flight safety. The pure rolling motion of the balls 132 in the arc-shaped groove 131 reduces friction loss, heat generation and wear compared to sliding friction or mechanical hinges, making the transmission smooth and efficient.

[0029] like Figure 1-8 The sphere 13, the placement plate 15, and the connecting ring 14 are sequentially sleeved from the inside to the outside and are all fitted onto the outer walls of the first main shaft 1 and the second main shaft 11. In order to facilitate the installation of the sphere 13 on the first main shaft 1 and the second main shaft 11, a number of limiting teeth 18 are provided circumferentially on the outer walls of the first main shaft 1 and the second main shaft 11 corresponding to the sphere 13. The length direction of each limiting tooth 18 is distributed along the length direction of the first main shaft 1 or the second main shaft 11. The sphere 13 is provided with a central hole for connecting with the outer walls of the first main shaft 1 and the second main shaft 11. The inner wall of the central hole of the sphere 13 is provided with a locking tooth 181 for inserting between two adjacent limiting teeth 18. The first main shaft 1 and the second main shaft 11 are both provided with limiting members to restrict the sphere 13 from sliding along the axis of the first main shaft 1 or the second main shaft 11.

[0030] like Figure 1-8The limiting component includes a lower chuck 182 sleeved on the outer wall of the first spindle 1 and the second spindle 11. The lower chuck 182 is an annular disc and is located below the ball 13. The inner wall of the lower chuck 182 is provided with lower stop teeth 183 that insert between two adjacent limiting teeth 18. The lower end of each lower stop tooth 183 is lower than the lower end of each limiting tooth 18. The outer walls of the first spindle 1 and the second spindle 11 are provided with a first stepped surface 184 that supports the lower end of each lower stop tooth 183. The upper end of the lower chuck 182 passes through the placement plate 15 and is supported on the ball 13. At the lower end, the first spindle 1 and the second spindle 11 are provided with clamping members above the ball 13 to press the ball 13 against the upper end face of the lower chuck 182. At this time, the upper and lower end faces of each ball 13 are provided with horizontal surfaces. The clamping members and the upper end face of the lower chuck 182 respectively abut against the upper and lower horizontal surfaces of the ball 13. The horizontal surface structure makes the axial clamping force evenly distributed, reducing the tilting or uneven wear of the ball 13 due to uneven end face force. At the same time, the planar contact between the horizontal surface and the clamping members increases the contact area, reduces the contact compressive stress, and improves the reliability of the connection.

[0031] like Figure 1-8 The clamping component includes an upper pressure plate 185 sleeved on the outer wall of the first spindle 1 and the second spindle 11. The upper pressure plate 185 is also an annular plate. The inner wall of the upper pressure plate 185 is provided with an upper stop tooth (not shown in the figure) that inserts between two adjacent limit teeth 18. The upper end of the upper stop tooth is higher than the upper end of the limit tooth 18. The outer wall of the first spindle 1 and the second spindle 11 is sleeved with a locking plate 186 located above the upper pressure plate 185. The inner wall of the locking plate 186 is threadedly connected to the outer wall of the first spindle 1 and the second spindle 11. At this time, the locking plate 186 is rotated until the locking plate 186 presses the upper pressure plate 185 onto the upper horizontal surface of the ball 13. At this time, the ball 13 is limited between the lower chuck 182 and the upper pressure plate 185.

[0032] like Figure 7 and Figure 8 The outer wall of the lower chuck 182 is tapered, and the smaller end of the outer wall enters the placement plate 15. The inner wall of the placement plate 15 that abuts against the outer wall of the lower chuck 182 is a conical surface 187 that matches the tapered shape.

[0033] After the locking plate 186 and the upper pressure plate 185 come into contact, the locking plate 186 and the upper pressure plate 185 are connected by several locking screws, which strengthens the connection between the locking plate 186 and the upper pressure plate 185 and reduces the loosening of the locking plate 186.

[0034] like Figure 1-8 The upper end of the placement plate 15 is provided with a connecting plate 188 extending to the upper end face of the connecting ring 14. The connecting plate 188 and the connecting ring 14 are connected by several fastening screws. At this time, the connecting plate 188 and the connecting ring 14 can be disassembled and installed by removing and installing each fastening screw.

[0035] The connecting plate 188 and the connecting ring 14 are detachably connected, allowing the placement plate 15 to be removed separately from the inside of the connecting ring 14. When internal components such as the ball 13 and the ball bearing 132 are worn or damaged, it is not necessary to replace the entire connecting ring 14. Only the connecting plate 188 needs to be removed to take out the placement plate 15 for maintenance, reducing maintenance costs and downtime. The connecting plate 188 extends outward from the upper end of the placement plate 15 to the upper end face of the connecting ring 14, forming a clear axial limiting structure. During assembly, the lower end face of the connecting plate 188 fits against the upper end face of the connecting ring 14, which can accurately position the axial position of the placement plate 15 inside the connecting ring 14, preventing the placement plate 15 from moving up and down during operation and ensuring the fitting accuracy between the ball 13 and the embedded groove 152.

[0036] The inner wall of the connecting plate 188 and the inner wall of the placement plate 15 are integrally formed and are both spherical surfaces 151 that mate with the ball 13. The height of the connecting plate 188 is higher than the center of the ball 13. The retainer 16 is limited within the inner wall of the connecting plate 188. The upper end of the embedding groove 152 extends out of the upper surface of the connecting plate 188.

[0037] The number of grooves 131 on each sphere 13 is 4 to 12, and a ball bearing 132 is set in each groove 131. The number of grooves 131 can be adjusted to match the load requirements of helicopters of different tonnages.

[0038] like Figure 1-8 The lower outer wall of the sphere 13 is provided with a third step surface 133 distributed in an annular pattern. The lower end of the groove 131 extends into the third step surface 133 and the retainer 16 is located above the third step surface 133. The lower inner wall of the placement tray 15 is provided with a fourth step surface 19 that contacts the third step surface 133. The lower end of the embedding groove 152 extends into the fourth step surface 19. Both the third step surface 133 and the fourth step surface 19 have gaps with the lower end of the retainer 16 and are both located below the retainer 16. The sum of the widths of the third step surface 133 and the fourth step surface 19 is equal to the thickness of the retainer 16.

[0039] The third step surface 133 and the fourth step surface 19 achieve axial positioning and limiting between the ball 13 and the placement plate 15. The third step surface 133 and the fourth step surface 19 are in contact with each other, forming a support for the ball 13. The third step surface 133 and the fourth step surface 19 are both located below the cage 16 and maintain a gap with the lower end of the cage 16. This structure achieves the following beneficial effects: Under normal working conditions, the cage 16 is in a free floating state and has no contact with the third step surface 133 and the fourth step surface 19, reducing friction loss and wear, and ensuring the smoothness and efficiency of the rolling transmission pair; when the cage 16 moves downward due to severe vibration or inertial force, the third step surface 133 and the fourth step surface 19 can contact the cage 16 in time and provide mechanical axial stop, reducing the cage 16 from falling out and the balls 132 from scattering, and reducing structural disintegration.

[0040] The ball 13, ball 132, and groove 131 can be made of bearing steel (such as GCr15) and heat-treated; the cage 16 can be made of copper alloy or polyetheretherketone.

[0041] Lubrication method: Grease can be pre-placed in the groove 131 or the placement hole 161 to further reduce friction.

[0042] The outer wall of the connecting ring 14 is provided with a plurality of through holes 141 spaced apart circumferentially. The fastening screws are located between two adjacent through holes 141, and the wall thickness of the connecting ring 14 at the fastening screws is greater than the wall thickness at the non-fastening screws locations. This design has the following beneficial effects: Balancing strength and lightweight: Local thickening at the fastening screw connection ensures the strength of the threaded connection; through holes 141 are opened in non-stressed areas to reduce the overall weight and achieve optimal structural efficiency; Heat dissipation and chip removal: Through hole 141 can be used as a heat dissipation hole and chip removal hole to reduce the internal working temperature and prevent chip accumulation; the thickened area provides a longer thread engagement length, enhances anti-loosening ability, and improves connection reliability; The alternating distribution of through holes 141 and thickened areas allows for periodic release of circumferential stress, reducing stress concentration and accumulation.

[0043] The number of fastening screws exceeds the number of embedded slots 152, ensuring the overall reliability of the transmission structure.

[0044] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0045] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A transmission structure for a helicopter rotor drum, characterized in that, It includes a first main shaft (1) and a second main shaft (11) that are coaxially distributed and rotate in opposite directions, with the second main shaft (11) fitted inside the first main shaft (1); The blade groups are all set on the first main shaft (1) and the second main shaft (11), and each blade group contains two blades (12). Spheres (13) are coaxially and detachably connected to the outer wall of the first main shaft (1) and the outer wall of the second main shaft (11). Several grooves (131) are provided on the outer wall of each sphere (13) along the circumferential direction, and the length direction of each groove (131) is distributed along the arc of the outer spherical surface (151) of the sphere (13); Rolling balls (132) are respectively connected to each groove (131) in a rolling manner. A connecting ring (14) that connects two blades (12) in the same blade group; A placement tray (15) is detachably connected to the inside of the connecting ring (14), the placement tray (15) having an inner cavity for accommodating the corresponding sphere (13); A retainer (16) is fitted around each ball (13), and the retainer (16) has a placement hole (161) for accommodating the ball (132). The inner wall of the placement plate (15) is configured as a spherical surface (151) that matches the outer surface of the corresponding ball (13), and an embedding groove (152) is provided on the spherical surface (151) for one end of the ball (132) to be embedded.

2. The transmission structure of the helicopter rotor drum as described in claim 1, characterized in that, The first spindle (1) and the second spindle (11) are provided with a plurality of limiting teeth (18) on the outer circumference of the corresponding sphere (13). The inner wall of the sphere (13) is provided with a locking tooth (181) that can be inserted between two adjacent limiting teeth (18). The first spindle (1) and the second spindle (11) are provided with limiting members to restrict the sphere (13) from sliding along the axis of the first spindle (1) or the second spindle (11).

3. The transmission structure of the helicopter rotor drum as described in claim 2, characterized in that, The limiting component includes a lower chuck (182) sleeved on the outer wall of the first spindle (1) and the second spindle (11). The lower chuck (182) is located below the ball (13). The inner wall of the lower chuck (182) is provided with a lower stop tooth (183) that inserts between two adjacent limiting teeth (18). The outer wall of the first spindle (1) and the second spindle (11) is provided with a first step surface (184) that supports the lower end of each lower stop tooth (183). The upper end of the lower chuck (182) passes through the placement plate (15) and is supported on the lower end of the ball (13). The first spindle (1) and the second spindle (11) are provided with a clamping component above the ball (13) to press the ball (13) against the upper end surface of the lower chuck (182).

4. The transmission structure of the helicopter rotor drum as described in claim 3, characterized in that, The clamping component includes an upper pressure plate (185) sleeved on the outer wall of the first spindle (1) and the second spindle (11). The inner wall of the upper pressure plate (185) is provided with an upper stop tooth that inserts between two adjacent limit teeth (18). The upper end of the upper stop tooth is higher than the upper end of the limit tooth (18). The outer wall of the first spindle (1) and the second spindle (11) is sleeved with a locking plate (186) located above the upper pressure plate (185). The inner wall of the locking plate (186) is threadedly connected to the outer wall of the first spindle (1) and the second spindle (11).

5. The transmission structure of the helicopter rotor drum as described in claim 4, characterized in that, The outer wall of the lower chuck (182) is tapered, and the smaller end of the outer wall enters the placement plate (15). The inner wall of the placement plate (15) that abuts against the outer wall of the lower chuck (182) is a conical surface (187) that matches the tapered shape.

6. The transmission structure of the helicopter rotor drum as described in claim 5, characterized in that, After the locking disc (186) and the upper pressure disc (185) come into contact, the locking disc (186) and the upper pressure disc (185) are connected by a number of locking screws.

7. The transmission structure of the helicopter rotor drum as described in claim 1, characterized in that, The upper end of the placement plate (15) is provided with a connecting plate (188) extending to the upper surface of the connecting ring (14), and the connecting plate (188) and the connecting ring (14) are connected by a number of fastening screws.

8. The transmission structure of the helicopter rotor drum as described in claim 7, characterized in that, The inner wall of the connecting plate (188) and the inner wall of the placement plate (15) are integrally formed and are both spherical surfaces (151) that cooperate with the sphere (13). The height of the connecting plate (188) is higher than the center of the sphere (13). The retainer (16) is limited in the inner wall of the connecting plate (188). The upper end of the embedding groove (152) extends out of the upper end surface of the connecting plate (188).

9. The transmission structure of the helicopter rotor drum as described in claim 1, characterized in that, The number of grooves (131) on each sphere (13) is 4 to 12, and a ball (132) is set in each groove (131).

10. The transmission structure of the helicopter rotor drum as described in claim 1, characterized in that, The lower outer wall of the sphere (13) is provided with a third step surface (133) distributed in a ring, and the lower inner wall of the placement tray (15) is provided with a fourth step surface (19) that contacts the third step surface (133). Both the third step surface (133) and the fourth step surface (19) have gaps with the lower end of the retainer (16). The sum of the widths of the third step surface (133) and the fourth step surface (19) is the thickness of the retainer (16).

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