Connecting structure of wave generator and input shaft of harmonic reducer

Abstract

The utility model relates to a connecting structure of a wave generator and an input shaft of a harmonic reducer, which comprises the wave generator and the input shaft, one end of the input shaft is provided with external spline teeth, the middle part of the wave generator is provided with a step-shaped through hole, and the wall of the through hole with the minimum aperture is provided with internal spline teeth. The input shaft is inserted into the through hole of the wave generator, and clamping springs are arranged on the two sides of the through hole, with the minimum aperture, of the input shaft in a clamped mode respectively. The spline is adopted as a main torque transmission and radial positioning mode which is obviously superior to interference fit, the spline meshing face is large, the bearing capacity is high, meanwhile, the excellent radial centering precision can be provided, the coaxiality of the wave generator and the input shaft is effectively guaranteed, the vibration and noise risks are reduced fundamentally, and the service life of the wave generator is prolonged. And the service life of the flexible gear is prolonged. In addition, the structure that double clamp springs are used for axial limiting is adopted, so that the overall structure is extremely compact and reliable, and assembling is easy, convenient and efficient.

Description

Technical Field

[0001] This utility model belongs to the field of robot joint module technology, and in particular relates to a connection structure between the wave generator and the input shaft of a harmonic reducer. Background Technology

[0002] Harmonic reducers, as precision power transmission devices, are widely used in high-precision motion control fields such as industrial robots, aerospace, and precision machine tools due to their advantages of high reduction ratio, small size, high precision, and zero backlash. The connection structure between its core component, the wave generator, and the input shaft directly determines the reliability of power transmission, coaxial accuracy, and overall operational smoothness of the machine.

[0003] Traditional wave generators are connected to the input shaft in two main ways:

[0004] I. Interference Fit: This method utilizes the interference fit between the shaft and the hole to achieve torque transmission and fixation. Its disadvantages include: 1. Difficulty in assembly and disassembly: Installation and disassembly require significant pressure or heating / cooling, making operation inconvenient and easily damaging the mating surfaces. 2. Risk of fretting wear: Under alternating loads, fretting wear may occur on the mating surfaces, leading to loosening of the fit or the generation of wear debris that contaminates the inside of the reducer. 3. Effects of thermal expansion: Operating temperature rise may affect the interference fit, resulting in either loosening or excessive tightness.

[0005] II. Flange and Bolt Connection: The wave generator is connected to the input shaft via a flange and bolts. While this method offers reliable connection, it still has the following drawbacks: 1. Complex structure and large size: The addition of flanges and bolts hinders the miniaturization and weight reduction of the harmonic reducer. 2. Dynamic balancing challenges: Multiple bolt connection points may introduce imbalances, affecting the smoothness of high-speed operation. 3. Low assembly efficiency: Multiple bolts need to be tightened, increasing assembly time and cost.

[0006] The key challenge of existing technologies lies in the difficulty of simultaneously achieving high-precision centering, efficient and reliable torque transmission, simple axial positioning and assembly, and compact structural design. Especially in applications requiring high precision, high reliability, and long lifespan, traditional connection methods are significantly inadequate in suppressing vibration, ensuring coaxiality, avoiding stress concentration, and simplifying assembly. Utility Model Content

[0007] To address the aforementioned technical problems, the present invention aims to provide a connection structure between the wave generator and the input shaft of a harmonic reducer. This structure improves transmission accuracy and flexspline life, and is easy to install.

[0008] To achieve the above-mentioned objectives, this utility model adopts the following technical solution:

[0009] A connection structure between a wave generator and an input shaft of a harmonic reducer includes a wave generator and an input shaft. One end of the input shaft is provided with external splines. The wave generator has a stepped through hole in the middle, and internal splines are provided on the wall of the through hole with the smallest diameter. The input shaft is inserted into the through hole of the wave generator, and retaining rings are respectively attached to both sides of the through hole with the smallest diameter.

[0010] As a preferred embodiment, the wave generator includes an elliptical cam and a thin-walled bearing. The elliptical cam has an inverted frustum connecting section, and an outer protrusion is provided on one side of the outer wall of the inverted frustum connecting section. The thin-walled bearing is tightly fitted on the elliptical cam, and one side abuts against the outer protrusion.

[0011] As a preferred embodiment, the stepped through hole is provided in the elliptical cam and includes three hollow cylinders with different diameters. A stepped surface for installing the support bearing is formed between the outermost hollow cylinder and the middle hollow cylinder.

[0012] As a preferred embodiment, the external spline teeth and the internal spline teeth are centered by tooth flank centering and / or major diameter centering.

[0013] As a preferred embodiment, the other end of the input shaft is also fitted with a bearing, and the other end of the input shaft is also provided with a limiting ring, with one side of the bearing abutting against the limiting ring.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] This invention employs splines as the primary method for torque transmission and radial positioning, which is significantly superior to interference fits. Splines offer a large meshing surface and high load-bearing capacity, while providing excellent radial centering accuracy. This effectively ensures the coaxiality of the wave generator and the input shaft, fundamentally reducing vibration and noise risks and improving transmission accuracy and flexspline life. Furthermore, a double snap ring axial limiting structure is used, resulting in an extremely compact, reliable, and easily and efficiently assembled overall structure. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0017] Figure 1 and Figure 2 This is a schematic diagram showing the connection between the wave generators at two different angles and the input shaft of this utility model;

[0018] Figure 3 This is a schematic diagram of the disassembled structure of the wave generator and input shaft of this utility model in a cut-off state;

[0019] Figure 4This is a cross-sectional structural diagram of the wave generator and input shaft of this utility model;

[0020] Figure 5 This is a schematic diagram of the elliptical cam of this utility model.

[0021] The attached figures are labeled as follows: 32, input shaft; 321, limiting ring; 5, elliptical cam; 50, outer flange; 51, stepped surface; 52, inverted frustum connecting section; 53, internal spline; 6, thin-walled bearing; 12, snap ring. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Furthermore, in the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0026] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 utility model according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0029] A joint module includes a housing, a stator assembly, a rotor assembly, a harmonic reducer, and a T-shaped shaft. The stator assembly is fixed to the inner wall of the housing. The rotor assembly includes an input shaft 32 and a rotor core 31 fixed on the input shaft 32. One end of the input shaft 32 is rotatably connected to the housing via a bearing. A cover plate is fixed to one end of the housing, and the other end of the input shaft 32 passes through the cover plate. The harmonic reducer includes a wave generator, a flexible wheel, and an output bearing. The wave generator is located at the other end of the input shaft 32 and rotates synchronously with the input shaft 32. The output bearing includes an inner bearing ring and an outer bearing ring. The outer bearing ring is fixed to an end cover. A steel wheel is integrated on the inner bearing ring. The flexible wheel is sleeved outside the wave generator and drives the steel wheel with staggered teeth. The T-shaped shaft includes an output disk and a hollow output shaft that are interconnected. The output disk is fixed to the end face of the inner bearing ring. The hollow output shaft passes through the wave generator and the input shaft 32 and is rotatably connected to the wave generator via a support bearing.

[0030] The other end of the input shaft 32 is also tightly fitted with a bearing, and a limiting ring 321 is also provided at the other end of the input shaft 32. One side of the bearing abuts against the limiting ring 321. The limiting ring and the cover plate together constrain the inner ring of the bearing, preventing axial movement of the input shaft and improving the rigidity of the rotor system. In addition, the bearing bears the radial force, and the limiting ring bears the axial force, which clearly defines their functions and extends their service life.

[0031] A gap is left between the hollow output shaft and the input shaft 32, and a bearing bush is also provided between them. This structure meets the requirements of hollow cabling and ultra-high rigidity. The hollow output shaft is rotatably connected to the wave generator via a support bearing, while radial decoupling is achieved between it and the input shaft 32 through a gap and bearing bush design. This structure ensures sufficient space for cable routing while directly constraining the coaxiality of the wave generator and the output shaft using the support bearing, thus suppressing transmission chain errors at their source.

[0032] A torque sensor is also fixed to the end cover, or the end cover itself is a torque sensor. This structure allows for seamless integration of torque sensing functionality, with the cover serving as a multi-functional carrier, capable of directly mounting the torque sensor or functioning as a sensor itself. Because the output disc is directly fixed to the inner ring of the bearing, while the outer ring is fixed to the cover, the reducer's output torque is transmitted to the cover without attenuation, creating a zero-hysteresis path for high-precision torque detection.

[0033] like Figures 1 to 4 As shown, one end of the input shaft 32 has external splines, and the wave generator has a stepped through hole in the middle. The wall of the through hole with the smallest diameter has internal splines 53. The input shaft 32 is inserted into the through hole of the wave generator, and retaining rings 12 are respectively secured on both sides of the through hole with the smallest diameter. The external splines and internal splines 53 are centered using tooth flank centering and / or large diameter centering. This structure uses spline meshing to achieve high-torque synchronous transmission, avoiding the risk of slippage in keyed connections and achieving efficient power transmission. Simultaneously, double retaining rings lock the wave generator to prevent axial displacement on the input shaft, ensuring meshing stability.

[0034] The wave generator includes an elliptical cam 5 and a thin-walled bearing 6. The elliptical cam 5 has a frustum-shaped connecting section 52, and an outer protrusion 50 is provided on one side of the outer wall of the frustum-shaped connecting section 52. The thin-walled bearing 6 is tightly fitted onto the elliptical cam 5, and one side abuts against the outer protrusion 50. In the above structure, the thin-walled bearing closely follows the elliptical contour of the cam, ensuring precise and controllable deformation of the flexspline and improving transmission efficiency; and the outer protrusion prevents axial displacement of the thin-walled bearing, avoiding dislocation during operation.

[0035] like Figure 5 As shown, the stepped through-hole is disposed in the elliptical cam 5 and includes three hollow cylinders with different diameters. A stepped surface 51 for mounting a support bearing is formed between the outermost hollow cylinder and the middle hollow cylinder. In the above structure, the support bearing (for the T-shaped shaft) is directly mounted on the stepped surface, eliminating the need for a separate bearing seat and simplifying the structure. In addition, the three diameters are adapted to different components (spline section, bearing section, and shaft passage section), optimizing space utilization.

[0036] This utility model's connection structure combines high-precision spline centering and torque transmission with a unique two-sided snap ring bidirectional axial limiting structure, and cleverly utilizes stepped holes to achieve spatial arrangement. This structural combination scheme unprecedentedly achieves the following effects simultaneously: 1. Excellent radial centering accuracy and torque transmission capability (spline); 2. Extremely high axial stiffness and stability, completely eliminating the cantilever effect (double snap rings); 3. Extremely compact and lightweight structure (embedded snap rings, no additional flanges); 4. Extremely simple and efficient assembly (insertion fitting + snap rings).

[0037] The present invention effectively overcomes the comprehensive problems of traditional connection methods in terms of accuracy, rigidity, vibration suppression, structural complexity and assembly convenience, and provides a high-performance, highly reliable and easy-to-manufacture and assemble wave generator and input shaft connection solution for high-precision harmonic reducers.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A connection structure between the wave generator and the input shaft of a harmonic reducer, characterized in that: The device includes a wave generator and an input shaft. One end of the input shaft (32) is provided with external splines. The wave generator has a stepped through hole in the middle, and the wall of the through hole with the smallest diameter is provided with internal splines (53). The input shaft (32) is inserted into the through hole of the wave generator, and snap rings (12) are respectively attached to both sides of the through hole with the smallest diameter.

2. The connection structure between the wave generator and the input shaft of a harmonic reducer according to claim 1, characterized in that, The wave generator includes an elliptical cam (5) and a thin-walled bearing (6). The elliptical cam (5) is provided with an inverted frustum connecting section (52). An outer protrusion (50) is also provided on one side of the outer wall of the inverted frustum connecting section (52). The thin-walled bearing (6) is tightly fitted on the elliptical cam (5) and one side abuts against the outer protrusion (50).

3. The connection structure between the wave generator and the input shaft of a harmonic reducer according to claim 1, characterized in that, The stepped through hole is provided in the elliptical cam (5) and includes three hollow cylinders with different diameters. The outermost hollow cylinder and the middle hollow cylinder form a stepped surface (51) for installing the support bearing.

4. The connection structure between the wave generator and the input shaft of a harmonic reducer according to claim 1, characterized in that, The external spline teeth and internal spline teeth (53) are centered by tooth flank centering and / or major diameter centering.

5. The connection structure between the wave generator and the input shaft of a harmonic reducer according to claim 1, characterized in that, The other end of the input shaft (32) is also fitted with a bearing, and the other end of the input shaft (32) is also provided with a limiting ring (321), one side of the bearing abuts against the limiting ring (321).

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