A transmission shaft structure and a telescopic drive structure

Abstract

This application relates to a transmission structure. Addressing the technical problems of low transmission accuracy, poor lubrication, large commutation impact, easy wear, and transmission failure in the power transmission structure of the main rotor in existing rotorcraft, this application proposes a transmission shaft structure and a telescopic drive structure. Two helical grooves with a 90° phase difference are provided on both the inner surface of the outer shaft and the outer surface of the inner shaft. Multiple rolling elements are installed at the intersection of the inner and outer helical grooves. By installing rolling elements in the helical grooves, the transmission backlash is reduced, improving response speed and control accuracy. The 90° phase difference helical groove design ensures smooth transmission between the outer and inner shafts and prevents disengagement.

Description

Technical Field

[0001] This application pertains to a transmission structure, specifically a transmission shaft structure and a telescopic drive structure. Background Technology

[0002] When rotary-wing aircraft (such as helicopters and tiltrotor aircraft) switch between vertical takeoff and landing and cruise flight, the tilt angle of the main rotor needs to be adjusted. In traditional technology, the power transmission of the main rotor often uses a fixed-shaft or splined telescopic shaft structure. These structures mainly have the following problems: (1) The large clearance leads to low transmission accuracy and is prone to vibration and noise.

[0003] (2) Poor lubrication, especially under high speed and high load conditions, can easily lead to overheating and wear.

[0004] (3) The reversal impact is large, which affects flight stability and control accuracy.

[0005] (4) The tilting mechanism is complex, and traditional hydraulic cylinders are difficult to withstand lateral forces and are prone to wear.

[0006] (5) Gear transmission is prone to disengagement during tilting, resulting in power interruption.

[0007] To address the aforementioned problems, various improvement solutions have been proposed in the existing technology. For example, using a lubricated spline shaft or adding auxiliary support structures, but these solutions have not fundamentally solved the problems of transmission accuracy, lubrication, and tilt synchronization. Summary of the Invention

[0008] This application addresses the technical problems of low transmission accuracy, poor lubrication, large commutation impact, easy wear, and easy transmission failure in the power transmission structure of the main rotor in existing rotorcraft, and proposes a transmission shaft structure and a telescopic drive structure.

[0009] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application proposes a transmission shaft structure, comprising: an inner shaft and an outer shaft coaxially sleeved together, and a plurality of rolling elements; The inner surface of the outer shaft has two inner spiral grooves with a 90° phase difference; the outer shaft is connected to the output end of an external rotary drive assembly. Two external helical grooves with a 90° phase difference are formed on the outer surface of the inner shaft; the inner helical groove and the outer helical groove correspond to and are adapted to each other; the inner shaft is connected to the output end of the external telescopic drive assembly; the inner helical groove and the outer helical groove rotate in opposite directions; The multiple rolling elements are respectively installed at the intersection of the inner spiral groove and the outer spiral groove.

[0010] Furthermore, it also includes a cage; the cage is installed between the inner shaft and the outer shaft, and the cage has a rolling element mounting groove, in which the rolling element is installed; The cage is provided with an oil channel for delivering lubricating medium to the rolling elements.

[0011] Furthermore, the cage includes a plurality of sub-cages; the plurality of sub-cages are evenly distributed along the axial direction.

[0012] Furthermore, the rolling element is a ball bearing.

[0013] Secondly, this application proposes a telescopic drive structure, including: a rotary drive assembly, a telescopic drive assembly, and the aforementioned transmission shaft structure; The output end of the rotary drive assembly is connected to the outer shaft; The output end of the telescopic drive assembly is connected to the inner shaft.

[0014] Furthermore, the output end of the telescopic drive assembly is connected to the inner shaft via an angular contact bearing.

[0015] Furthermore, it also includes the bearing housing; The output end of the telescopic drive assembly is provided with a mounting joint, which is sleeved on the outside of the inner shaft, and the mounting joint and the inner shaft are connected by a first angular contact bearing. The bearing housing is sleeved and installed outside the output end of the telescopic drive assembly, and the output end of the telescopic drive assembly is connected to the bearing housing through a second angular contact bearing.

[0016] Furthermore, it also includes a first retaining ring and a second retaining ring; The first snap ring is mounted on the inner shaft, and the second snap ring is mounted on the bearing seat of the second angular contact bearing; the first snap ring and the second snap ring are used to define the axial positions of the first angular contact bearing and the second angular contact bearing, respectively.

[0017] Furthermore, a first limiting step is provided on the inner shaft; a second limiting step is provided on the outer wall of the output end of the second angular contact telescopic drive assembly; The first angular contact bearing is installed between the first limiting step and the first retaining ring; The second angular contact bearing is installed between the second limiting step and the second snap ring.

[0018] Furthermore, the telescopic drive assembly is a hydraulic drive assembly.

[0019] Compared with the prior art, this application has the following beneficial effects: This application proposes a transmission shaft structure with two helical grooves, each 90° out of phase, on both the inner and outer surfaces of the outer shaft. Multiple rolling elements are installed at the intersection of the inner and outer helical grooves. This structure, by installing rolling elements within the helical grooves, reduces transmission backlash and improves response speed and control accuracy. The 90° phase difference between the two helical grooves, combined with the opposite rotation directions of the inner and outer helical grooves, ensures smooth transmission between the outer and inner shafts, preventing disengagement. Therefore, the transmission shaft structure proposed in this application provides stable and smooth transmission, is less prone to wear, and offers high transmission accuracy. It is more suitable for applications requiring high loads, long-cycle operation, and high reliability.

[0020] This application also proposes a telescopic drive structure that possesses all the advantages of the aforementioned drive shaft structure. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of an outer spiral groove on an inner shaft according to an embodiment of the transmission shaft structure of this application; Figure 2 This is a schematic diagram of an inner spiral groove on an outer shaft according to an embodiment of the transmission shaft structure of this application; Figure 3 This is a schematic diagram of the installation of the rolling element in the embodiment of the transmission shaft structure of this application; Figure 4 This is a schematic diagram of the sub-cage in the transmission shaft structure embodiment of this application; Figure 5 This is a schematic diagram of the installation of the first angular contact bearing and the second angular contact bearing in the embodiment of the telescopic drive structure of this application.

[0023] Wherein: 1-rolling element, 2-outer shaft, 3-inner shaft, 4-inner spiral groove, 5-outer spiral groove, 6-cage, 7-rolling element mounting groove, 8-sub-cage, 9-rotary drive assembly, 10-telescopic drive assembly, 11-first angular contact bearing, 12-second angular contact bearing, 13-first snap ring, 14-second snap ring, 15-bearing housing, 16-first limiting step, 17-second limiting step, 18-mounting joint, 19-rotor of the rotary motor, 20-oil seal, 21-output end of the telescopic drive assembly, 22-stator and mounting frame of the rotary motor. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 application according to the specific circumstances.

[0030] In the operation of rotorcraft such as helicopters and tiltrotor aircraft, the switching between vertical takeoff and landing and cruise flight modes hinges on the precise adjustment of the main rotor's tilt angle. The reliability and stability of this adjustment process directly depend on the performance of the main rotor's power transmission system. Currently, the mainstream power transmission structure is still based on fixed shafts or spline telescopic shafts. However, in practical applications, these traditional structures have revealed multi-dimensional technical defects and have become a key bottleneck restricting the improvement of rotorcraft flight performance.

[0031] The inherent clearance in the design of the fixed shaft and spline telescopic shaft directly leads to a decrease in transmission accuracy during power transmission. During dynamic transitions between aircraft operating conditions, the vibration caused by this clearance is particularly pronounced, generating high-frequency noise and potentially exacerbating structural fatigue, thus affecting overall aircraft stability. Traditional lubrication methods are also insufficient for complex operating conditions, especially under high-speed rotation (e.g., high speeds during cruise) and high loads (e.g., heavy loads during vertical takeoff and landing). The uniformity of lubricant distribution and adhesion stability decrease significantly, leading to frequent localized overheating of transmission components, accelerating wear, and shortening service life. Furthermore, during the reversal process of main rotor tilt adjustment, traditional structures lack effective buffering and transition mechanisms. Sudden changes in power transmission direction and load result in significant mechanical shocks. These shocks not only affect flight stability and increase the difficulty of attitude control but also reduce the control accuracy of tilt adjustment, making it difficult to meet the requirements of high-precision flight missions.

[0032] To address the aforementioned technical shortcomings, relevant improvement research has been conducted, proposing optimization solutions such as splined shafts with lubrication structures and transmission systems with added auxiliary supports. Among these, splined shafts with lubrication structures, through optimized lubrication channel design, alleviate the problem of poor local lubrication to some extent, but fail to fundamentally solve the core issues of low transmission accuracy and high vibration and noise caused by the mating clearance. While adding auxiliary support structures can improve the stability of the transmission system and reduce the impact of lateral forces on the tilting mechanism, it increases the structural complexity and weight of the transmission system, contradicting the lightweight design requirements of the aircraft.

[0033] Therefore, existing technologies have failed to form a systematic solution and cannot simultaneously meet the multi-dimensional requirements of transmission accuracy, lubrication effect, tilt synchronization, and lightweight structure. It is still necessary to break through the traditional design ideas and explore more efficient and reliable main rotor power transmission and tilt control technology paths.

[0034] Based on the above, this application proposes a transmission shaft structure and a telescopic drive structure that can be applied to various transmission scenarios. At the same time, it can also serve as a transmission structure for rotorcraft, achieving a high-precision, low-impact, and well-lubricated telescopic transmission mechanism while ensuring continuous power transmission.

[0035] As one embodiment of the transmission shaft structure of this application, it may include: an inner shaft 3 and an outer shaft 2 coaxially fitted together, and a plurality of rolling elements 1. Two inner helical grooves 4 with a 90° phase difference are formed on the inner surface of the outer shaft 2. The outer shaft 2 is connected to the output end of an external rotary drive assembly 9. Two outer helical grooves 5 with a 90° phase difference are formed on the outer surface of the inner shaft 3. The inner helical grooves 4 and the outer helical grooves 5 correspond and are adapted to each other. The inner shaft 3 is connected to the output end 21 of an external telescopic drive assembly. The inner and outer helical grooves rotate in opposite directions. The plurality of rolling elements 1 are respectively installed at the intersection of the inner helical grooves 4 and the outer helical grooves 5. Figure 1 The diagram shown is a schematic representation of the outer spiral groove 5 on the inner shaft 3 of an embodiment of the transmission shaft structure of this application. Figure 2 The diagram shown is a schematic diagram of the inner spiral groove 4 on the outer shaft 2 of an embodiment of the transmission shaft structure of this application.

[0036] The inner shaft 3 and outer shaft 2 are coaxially fitted to ensure that their axes are aligned, preventing misalignment during movement that could lead to jamming or wear. In this invention, the outer shaft 2 can rotate after receiving power from the rotary drive assembly 9, and its inner helical groove 4 pushes the rolling element 1 as it rotates. Since the rolling element 1 is in contact with the outer helical groove 5 of the inner shaft 3, it transmits the rotational force of the outer shaft 2 to the inner shaft 3, causing the inner shaft 3 to rotate in the same direction as the outer shaft 2. At the same time, the inner shaft 3 is also connected to the telescopic drive assembly 10. During the rotation in the same direction, the telescopic drive assembly 10 can control the inner shaft 3 to extend or retract along the axial direction, or when the inner shaft 3 needs to extend or retract due to external force, it can also complete linear motion while maintaining rotation in the same direction, preventing the inner shaft 3 and outer shaft 2 from rotating in opposite directions.

[0037] The outer helical groove 5 of the inner shaft 3 and the inner helical groove 4 of the outer shaft 2 are paired and rotate in the same direction. Their helical parameters are perfectly matched, which not only forms a rolling channel to accommodate the rolling element 1, but also ensures that the rotational force is transmitted in the same direction. When the outer shaft 2 rotates, the inner helical groove 4 pushes the rolling element 1 to roll in the channel, and the rolling element 1 will generate a thrust in the same direction on the outer helical groove 5. This thrust can be decomposed into two components: one is a component along the circumference of the inner shaft 3, which drives the inner shaft 3 to rotate in the same direction as the outer shaft 2; the other is a component along the axis of the inner shaft 3, which, with the cooperation of the telescopic drive assembly 10, drives the inner shaft 3 to perform linear telescopic motion. Conversely, when the inner shaft 3 needs to be telescopicated by external force, the outer helical groove 5 will push the rolling element 1 to roll, which in turn drives the inner helical groove 4 of the outer shaft 2 to rotate in the same direction, ensuring that the inner shaft 3 and the outer shaft 2 always rotate in the same direction and will not be in opposite directions. Throughout the entire operation, the rolling element 1 not only converts the sliding friction between the inner shaft 3 and the outer shaft 2 into rolling friction, reducing resistance, but also accurately transmits the rotation direction, ensuring that the inner shaft 3 and the outer shaft 2 rotate in the same direction.

[0038] In terms of motion accuracy, since the inner shaft 3 and outer shaft 2 always rotate in the same direction, the entire transmission structure will not experience accuracy deviations due to conflicting rotational directions during the combined motion of rotation and linear extension, meeting the requirements of high-precision equipment. Regarding power transmission efficiency, the characteristic of the rolling element 1 converting sliding friction into rolling friction, combined with the absence of reverse force loss during rotation in the same direction, improves overall transmission efficiency. The direct power transmission between the inner shaft 3 and outer shaft 2 and the rolling element 1 also reduces intermediate transmission links, further lowering power loss. Furthermore, the double-helix groove design with a 90° phase difference evenly distributes the pressure on the rolling element 1, reducing localized wear and thus effectively extending its service life.

[0039] In some embodiments of this application, a cage 6 is also included. The cage 6 is installed between the inner shaft 3 and the outer shaft 2. The cage 6 has a rolling element mounting groove 7, and the rolling element 1 is installed in the rolling element mounting groove 7. The cage 6 is installed between the inner shaft 3 and the outer shaft 2, and its main function is to position the rolling element 1 and provide a lubrication channel. First, the rolling element mounting groove 7 on the cage 6 will accommodate each rolling element 1 individually, avoiding collisions and squeezing of multiple rolling elements 1 at the intersection of the inner spiral groove 4 and the outer spiral groove 5, ensuring that each rolling element 1 can roll smoothly on a preset trajectory. Especially when the inner shaft 3 and the outer shaft 2 rotate in the same direction, it can prevent transmission jamming caused by the centrifugal force offset of the rolling element 1. In addition, the cage 6 itself can provide a lubrication channel. When the rolling element 1 rolls in the rolling element mounting groove 7, the cage 6 will slowly release lubricating oil or grease, evenly applying it to the contact surface between the rolling element 1 and the spiral groove, continuously reducing frictional resistance and avoiding damage to parts caused by dry friction. Figure 3 The diagram shown is a schematic representation of the installation of the rolling element 1 in an embodiment of the transmission shaft structure of this application. Figure 4 The diagram shown is a schematic representation of the sub-cage 8 in an embodiment of the drive shaft structure of this application. In practical applications, to further reduce weight, the cage 6 may include multiple sub-cages 8, which are evenly distributed along the axial direction. It should be noted that the number and size of the sub-cages 8 can be adjusted according to actual processing and usage needs, thereby reducing weight and enabling the structure of this application to have a wider range of applications.

[0040] In some embodiments of this application, the rolling element 1 may be a ball bearing. It may also be replaced with other rolling element structures depending on the actual situation, and the material may be adjusted according to usage requirements.

[0041] Based on the aforementioned drive shaft structure, this application also proposes a telescopic drive structure, which may include a rotary drive assembly 9, a telescopic drive assembly 10, and the aforementioned drive shaft structure. The output end of the rotary drive assembly 9 is connected to the outer shaft 2, and the output end 21 of the telescopic drive assembly is connected to the inner shaft 3.

[0042] This application integrates the rotary drive, telescopic drive, and transmission shaft into one unit, eliminating the need for additional transmission intermediaries, reducing power transmission links, and improving overall drive efficiency. The targeted connection between the rotary drive assembly 9 and the outer shaft 2, and the telescopic drive assembly 10 and the inner shaft 3, ensures precise power transmission. The inner shaft 3 can simultaneously achieve unidirectional rotation and linear telescopic extension, meeting the needs of complex motion.

[0043] As an example, the outer shaft 2 is connected to the rotary drive assembly 9, which uses a rotary motor. The rotor 19 of the rotary motor is installed in the stator and fixed frame 22 of the rotary motor. The rotary motor drives the outer shaft 2 to rotate. The telescopic drive assembly 10 uses a hydraulic telescopic assembly to push the inner shaft 3 to move axially.

[0044] like Figure 5 The diagram shows the installation of the first angular contact bearing 11 and the second angular contact bearing 12 in an embodiment of the telescopic drive structure of this application. As an example, it also includes a bearing housing 15, a first retaining ring 13, and a second retaining ring 14. The output end 21 of the telescopic drive assembly is provided with a mounting joint 18, which is sleeved on the outside of the inner shaft 3. The mounting joint 18 and the inner shaft 3 are connected via the first angular contact bearing 11. The bearing housing 15 is sleeved on the outside of the output end 21 of the telescopic drive assembly, and the output end 21 of the telescopic drive assembly is connected to the bearing housing 15 via the second angular contact bearing 12. Furthermore, to ensure the axial positioning of the first angular contact bearing 11 and the second angular contact bearing 12, the inner shaft 3 is provided with a first limiting step 16, and the outer wall of the output end 21 of the second angular contact telescopic drive assembly is provided with a second limiting step 17. The first angular contact bearing 11 is installed between the first limiting step 16 and the first retaining ring 13, and the second angular contact bearing 12 is installed between the second limiting step 17 and the second retaining ring 14. An oil seal 20 is provided at one end of the bearing housing 15 near the telescopic drive assembly 10.

[0045] Mounting connector 18 is fitted onto the outside of inner shaft 3, serving as a transition between the output end 21 of telescopic drive assembly and inner shaft 3. The first angular contact bearing 11 between mounting connector 18 and inner shaft 3 allows the inner shaft 3 to rotate freely within mounting connector 18 while also bearing the radial and axial loads generated during the telescopic extension and retraction of inner shaft 3. The second angular contact bearing 12 between the output end 21 of telescopic drive assembly and bearing housing 15 also bears radial and axial loads, ensuring smooth relative rotation between bearing housing 15 and the output end of telescopic drive assembly 10. To achieve axial positioning of the angular contact bearing, the first limiting step 16 on inner shaft 3 provides one-end support for the first angular contact bearing 11. After the first retaining ring 13 is engaged in the retaining groove of inner shaft 3, it presses against the first angular contact bearing 11 from the other end, fixing it between the first limiting step 16 and the first retaining ring 13. The second limiting step 17 on the outer wall of the output end of the telescopic drive assembly 10 supports one end of the second angular contact bearing 12. The second snap ring 14 is engaged with the slot of the bearing housing 15, fixing the second angular contact bearing 12 from the other end and preventing the bearing from moving axially. The oil seal 20 of the bearing housing 15 near the end of the telescopic drive assembly 10, together with the dust cover, can seal the internal space of the bearing housing 15 to prevent internal lubricating oil leakage, while blocking external dust and moisture from entering and preventing bearing wear.

[0046] The telescopic drive structure provided in this application, with its helical structure of rolling elements 1 and helical grooves, reduces transmission backlash and improves response speed and control accuracy. The cage 6 can be equipped with an oil channel to directly lubricate the rolling elements 1, effectively extending the service life of the telescopic drive structure. The phase difference design of the helical grooves ensures smooth transmission and prevents disengagement. It is suitable for high-load, long-cycle operation and offers high reliability.

[0047] It should be noted that the structure of this application can be applied to various scenarios that require telescopic and rotary drives. Due to its high precision and long service life, it is more suitable for some high-requirement application scenarios.

[0048] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A propeller shaft arrangement, characterized in that include: The inner shaft (3) and outer shaft (2) are coaxially fitted together, and multiple rolling elements (1); The inner surface of the outer shaft (2) is provided with two inner spiral grooves (4) with a phase difference of 90°; the outer shaft (2) is connected to the output end of the external rotary drive assembly (9); Two outer spiral grooves (5) with a phase difference of 90° are provided on the outer surface of the inner shaft (3); the inner spiral groove (4) and the outer spiral groove (5) are corresponding and adapted to each other; the inner shaft (3) is connected to the output end (21) of the external telescopic drive assembly; the inner spiral groove (4) and the outer spiral groove (5) have opposite rotation directions; Multiple rolling elements (1) are respectively installed at the intersection of the inner spiral groove (4) and the outer spiral groove (5).

2. A propeller shaft assembly according to claim 1, wherein It also includes a retainer (6); the retainer (6) is installed between the inner shaft (3) and the outer shaft (2), and the retainer (6) has a rolling element mounting groove (7), in which the rolling element (1) is installed; The cage (6) is provided with an oil channel for conveying lubricating medium to the rolling element (1).

3. The propeller shaft assembly of claim 2 wherein: The cage (6) includes a plurality of sub-cages (8); the plurality of sub-cages (8) are evenly distributed along the axial direction.

4. The propeller shaft assembly of claim 1 wherein: The rolling element (1) is a ball bearing.

5. A telescopic drive structure characterized by, include: The rotary drive assembly (9), the telescopic drive assembly (10), and the drive shaft structure according to any one of claims 1 to 4; The output end of the rotary drive assembly (9) is connected to the outer shaft (2); The output end (21) of the telescopic drive assembly is connected to the inner shaft (3).

6. The telescopic drive structure according to claim 5, characterized in that, The output end (21) of the telescopic drive assembly is connected to the inner shaft (3) via an angular contact bearing.

7. The telescoping drive structure of claim 6, wherein, It also includes the bearing housing (15); The output end (21) of the telescopic drive assembly is provided with a mounting joint (18), which is sleeved on the outside of the inner shaft (3). The mounting joint (18) and the inner shaft (3) are connected by a first angular contact bearing (11). The bearing housing (15) is sleeved and installed outside the output end (21) of the telescopic drive assembly. The output end (21) of the telescopic drive assembly and the bearing housing (15) are connected by a second angular contact bearing (12).

8. The telescoping drive structure of claim 7, wherein, It also includes a first retaining ring (13) and a second retaining ring (14); The first snap ring (13) is mounted on the inner shaft (3), and the second snap ring (14) is mounted on the bearing seat of the second angular contact bearing (12); the first snap ring (13) and the second snap ring (14) are respectively used to limit the axial position of the first angular contact bearing (11) and the second angular contact bearing (12).

9. The telescoping drive structure of claim 8, wherein, The inner shaft (3) is provided with a first limiting step (16); the outer wall of the output end (21) of the second angular contact telescopic drive assembly is provided with a second limiting step (17); The first angular contact bearing (11) is installed between the first limiting step (16) and the first retaining ring (13); The second angular contact bearing (12) is installed between the second limiting step (17) and the second snap ring (14).

10. The telescoping drive structure of claim 5, wherein, The telescopic drive assembly (10) is a hydraulic drive assembly.

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