Harmonic speed reducer and industrial robot

Abstract

A harmonic speed reducer (1000) and an industrial robot. The harmonic speed reducer (1000) comprises a circular spline (100), a flexspline (200), a wave generator (300), and a support bearing (400); the wave generator (300) is arranged in the flexspline (200), and an outer tooth part (210) of the flexspline (200) is partially meshed with an inner tooth part (110) of the circular spline (100); a first slot body (430) and a second slot body (440) are arranged between an inner bearing ring (410) and an outer bearing ring (420) of the support bearing (400); the first slot body (430) is used for mounting a first rolling body (431); and the second slot body (440) is used for mounting a second rolling body (441).

Description

Harmonic reducers and industrial robots

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent applications filed on November 22, 2024, with application numbers 202411686881.7 and 202422865036.8 and 202422865056.5, all of which are entitled "Harmonic Reducer and Industrial Robot". Technical Field

[0003] This application relates to the field of speed reducer technology, and in particular to a harmonic speed reducer and an industrial robot. Background Technology

[0004] In related technologies, harmonic reducers include a wave generator, a flexible wheel, and a rigid wheel. The wave generator is embedded in the inner hole of the flexible wheel, and the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel. When the wave generator rotates, it drives different parts of the outer and inner teeth to mesh, thereby causing relative rotation between the rigid wheel and the flexible wheel, achieving power output. The flexible wheel undergoes reciprocating deformation during operation and is therefore subjected to stress. Therefore, the design of the flexible wheel needs to minimize the stress generated during deformation. Although flexible wheels of the same specifications have the same inner hole diameter, different reduction ratios result in different numbers of teeth and modules, leading to different deformations. Therefore, it is difficult to design a suitable structure for the flexible wheel to reduce the magnitude of stress during deformation. Furthermore, the rigid wheel has high overall rigidity, and under high pressure on the flexible wheel, it is prone to interference with the rigid wheel, leading to increased vibration and noise in the harmonic reducer. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a harmonic reducer that can effectively reduce the stress on the flexural wheel during deformation, reduce the machining difficulty of the support bearing, and reduce interference between the rigid wheel and the flexural wheel, thereby reducing vibration and noise.

[0006] This application also proposes an industrial robot having the aforementioned harmonic reducer.

[0007] A harmonic reducer according to a first aspect of this application includes: a rigid wheel including an internal tooth portion; a flexible wheel disposed inside the rigid wheel, the flexible wheel including an external tooth portion; a wave generator disposed inside the flexible wheel and used to partially mesh the external tooth portion with the internal tooth portion; and a support bearing configured to enable the rigid wheel and the flexible wheel to rotate relative to each other, the support bearing including an outer bearing ring and an inner bearing ring disposed within the outer bearing ring, the inner bearing ring and the outer bearing ring having a first groove for mounting a first rolling element and a second groove for mounting a second rolling element, the first groove and the second groove being spaced apart along the axial direction of the wave generator; wherein the tooth root wall thickness of the flexible wheel is Tf, the inner diameter of the flexible wheel is Df, and the reduction ratio of the harmonic reducer is R, satisfying: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036.

[0008] The harmonic reducer according to the embodiments of this application has at least the following beneficial effects:

[0009] By positioning the wave generator inside the flexure and partially meshing the outer teeth of the flexure with the inner teeth of the rigid wheel, the wave generator's rotation drives relative rotation between the flexure and the rigid wheel. A first groove and a second groove are provided between the inner and outer bearing rings of the supporting bearing. The first groove is for mounting the first rolling element, and the second groove is for mounting the second rolling element. These two grooves are spaced apart along the axial direction of the wave generator. The use of two sets of rolling elements effectively enhances the load-bearing capacity of the harmonic reducer, improving assembly efficiency between the bearing assembly and the rigid and flexure wheels while maintaining overall structural compactness. Furthermore, by setting the ratio of the flexure's tooth root wall thickness Tf to its inner diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the stress distribution of harmonic reducers with different reduction ratios R is improved, reducing the stress on the flexure during deformation.

[0010] According to some embodiments of this application, along the axial direction, the effective width of the flexible wheel is Lf, and the width of the internal tooth is Lc, satisfying: 0.45*Lf≤Lc≤0.65*Lf.

[0011] According to some embodiments of this application, the rigid wheel further includes a first mounting portion connected to the inner bearing ring, the internal tooth portion being connected to the inner side of the first mounting portion, and the width of the internal tooth portion being greater than the width of the first mounting portion along the axial direction of the wave generator.

[0012] According to some embodiments of this application, the portion of the internal tooth protruding from the first mounting portion along the axial direction abuts against the inner side of the inner bearing ring; one end of the inner bearing ring along the axial direction is provided with a protrusion protruding toward the first mounting portion, and the inner side of the protrusion abuts against the outer side of the first mounting portion.

[0013] According to some embodiments of this application, the first mounting portion is connected to one end of the internal tooth portion that is axially away from the inner bearing ring.

[0014] According to some embodiments of this application, the flexible wheel further includes a cylinder, a diaphragm, and a flange. The external toothed portion is connected to the outer side of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, the flange is connected to the end of the diaphragm away from the cylinder, and the flange is fixedly connected to the outer bearing ring.

[0015] According to some embodiments of this application, along the axial direction of the wave generator, the first rolling element is located between the diaphragm and the internal tooth portion, the width of the internal tooth portion is Lc, and the minimum distance between the end face of the internal tooth portion facing the first rolling element and the center of the second rolling element is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc, where when L3>0, the center of the second rolling element is located between the two end faces of the external tooth portion along the axial direction, and when L3<0, the center of the second rolling element is located between the external tooth portion and the diaphragm.

[0016] According to some embodiments of this application, along the axial direction, the external tooth portion includes a first tooth segment away from the flange portion and a second tooth segment near the flange portion. The diameter of the tip circle of the first tooth segment gradually decreases in the direction away from the flange portion, and the diameter of the tip circle of the second tooth segment gradually decreases in the direction toward the flange portion.

[0017] According to some embodiments of this application, the external tooth portion further includes a third tooth segment located between the first tooth segment and the second tooth segment, wherein the diameter of the tip circle of the third tooth segment is constant.

[0018] According to some embodiments of this application, along the axial direction, the effective width of the flexible wheel is Lf, the width of the external tooth is Lf1, the width of the first tooth segment is Lf2, the width of the second tooth segment is Lf4, and the width of the third tooth segment is Lf3, satisfying: 0.4*Lf≤Lf1≤0.6*Lf; 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

[0019] According to some embodiments of this application, the inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.3°≤α1≤1.0°, 0.3°≤β1≤1.0°, and β1≥α1.

[0020] According to some embodiments of this application, the flexible wheel further includes a cylindrical portion, a diaphragm portion, and a flange portion. The external toothed portion is connected to the outer side of one end of the cylindrical portion, the diaphragm portion is connected to the other end of the cylindrical portion and extends radially along the cylindrical portion, the flange portion is connected to the end of the diaphragm portion away from the cylindrical portion, the flange portion and the outer bearing ring are fixedly connected, the effective width of the flexible wheel along the axial direction is Lf, the maximum distance between the outer bearing ring abutting the end wall of one end of the flange portion and the center of the first rolling element is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf; and / or, the effective width of the flexible wheel along the axial direction is Lf, and the maximum distance between the center of the first rolling element and the center of the second rolling element in a direction parallel to the axial direction is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

[0021] According to some embodiments of this application, the outer bearing ring includes a second mounting portion and a protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring has a groove that is opposite to the protrusion. The groove has a first inner raceway and a second inner raceway at both ends along the axial direction. The first inner raceway and the first outer raceway are opposite to each other and form the first groove. The second inner raceway and the second outer raceway are opposite to each other and form the second groove.

[0022] According to some embodiments of this application, there is a gap between the protrusion and the bottom wall of the groove, and the first groove and the second groove are connected through the gap.

[0023] According to some embodiments of this application, the inner bearing ring includes a first ring body and a second ring body connected to each other. The first inner raceway is located outside the first ring body and close to the second ring body, and the second inner raceway is located outside the second ring body and away from the first ring body. The second ring body is connected to the rigid wheel.

[0024] According to some embodiments of this application, within a cross-section passing through the rotation axis of the wave generator, the outer contour of the first inner raceway is a first curve. The first curve includes a first circular arc segment and a first shaping segment, the first shaping segment being a non-circular arc. The radius of the first circular arc segment is Ri, and the maximum cross-sectional diameter of the first rolling element is Db1. A coordinate system is established with the center of the first circular arc segment as the origin. The X-axis is parallel to the rotation axis and points away from the second rolling element, and the Y-axis is perpendicular to the X-axis and points towards the rotation axis. The first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi=Ri, when θ1>βi; where Ri=(0.505~0.515)*Db1, ki=0.002~0.004, βi=20°-30°.

[0025] According to some embodiments of this application, within the cross-section passing through the rotation axis of the wave generator, the outer contour of the first outer raceway is a second curve. The second curve includes a second circular arc segment and a second modified segment. The second modified segment is a non-circular arc. The radius of the second circular arc segment is Ro, and the maximum cross-sectional diameter of the first rolling element is Db1. A coordinate system is established with the center of the second circular arc segment as the origin. The X-axis is parallel to the rotation axis and points in the direction of the second rolling element, and the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis. The second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; where Ro=(0.505~0.515)*Db1, ko=0.002~0.004, and βo=20°-30°.

[0026] According to some embodiments of this application, the inner diameter of the flexure is Df, and the maximum cross-sectional diameter of the first rolling element is Db1, satisfying: 0.07*Df≤Db1≤0.13*Df; and / or, the inner diameter of the flexure is Df, and the diameter of the circle containing the centers of the plurality of first rolling elements perpendicular to the axial direction is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df.

[0027] The industrial robot according to the second aspect of this application includes the harmonic reducer described in the above embodiments.

[0028] The industrial robot according to the embodiments of this application has at least the following beneficial effects:

[0029] The harmonic reducer using the first aspect embodiment has a wave generator located inside the flexure, with the outer teeth of the flexure partially meshing with the inner teeth of the rigid wheel. Therefore, when the wave generator rotates, it can drive the flexure and rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the supporting bearing. The first groove is for mounting a first rolling element, and the second groove is for mounting a second rolling element. The first and second grooves are spaced apart along the axial direction of the wave generator. By providing two sets of rolling elements, the load-bearing capacity of the harmonic reducer can be effectively improved, maintaining the compactness of the overall structure while increasing the assembly efficiency between the bearing assembly and the rigid and flexure wheels. Simultaneously, by setting the ratio of the flexure tooth root wall thickness Tf to the flexure inner diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, it is suitable for improving the stress distribution of harmonic reducers with different reduction ratios R and reducing the stress on the flexure during deformation.

[0030] A harmonic reducer according to a third aspect of this application includes: a rigid wheel, including a first mounting portion and an internal tooth portion connected to the inner side of the first mounting portion; a flexible wheel, disposed inside the rigid wheel, the flexible wheel including an external tooth portion; a wave generator, disposed inside the flexible wheel and used to partially mesh the external tooth portion with the internal tooth portion; and a support bearing, configured to allow the rigid wheel and the flexible wheel to rotate relative to each other, the support bearing including an outer bearing ring and an inner bearing ring disposed within the outer bearing ring, the inner bearing ring and the outer bearing ring having a space between them for supplying a wave generator. A first groove for mounting a rolling element and a second groove for mounting a second rolling element are provided, the first groove and the second groove being spaced apart along the axial direction of the wave generator; wherein, the first mounting part is connected to the inner bearing ring, and along the axial direction of the wave generator, the first mounting part is connected to the end of the internal tooth portion away from the inner bearing ring, the internal tooth portion including a thin-walled section protruding from the first mounting part, the width of the thin-walled section being Lc1, and the width of the internal tooth portion being Lc, satisfying: 0.6*Lc≤Lc1≤0.9*Lc.

[0031] The harmonic reducer according to the embodiments of this application has at least the following beneficial effects:

[0032] By positioning the wave generator inside the flex wheel and partially meshing the outer teeth of the flex wheel with the inner teeth of the rigid wheel, the wave generator's rotation drives the flex wheel and rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the support bearing. The first groove is for mounting the first rolling element, and the second groove is for mounting the second rolling element. These two grooves are spaced apart along the axial direction of the wave generator. Using two sets of rolling elements effectively improves the load-bearing capacity of the harmonic reducer, while maintaining the overall compact structure and increasing the assembly efficiency between the bearing assembly and the rigid and flex wheels. Since the rigid wheel includes a connected first mounting portion and an inner tooth portion, and the first mounting portion is located at the end of the inner tooth portion away from the inner bearing ring, the inner bearing ring can extend to the outer wall of the inner tooth portion, resulting in a relatively long overall length. Setting mounting holes on the inner bearing ring has minimal impact on the raceway, reducing the machining difficulty of the support bearing. Meanwhile, since the internal teeth protrude from the first mounting part, the internal teeth are designed with thin walls, which can generate elastic deformation to a certain extent. Therefore, without reducing the meshing depth between the internal and external teeth, the elastic deformation of the internal teeth is used to reduce the interference between them, thereby improving the load-bearing capacity of the harmonic reducer and reducing vibration and noise.

[0033] According to some embodiments of this application, the maximum wall thickness of the thin-walled section is Tc, and the inner diameter of the flexible wheel is Df, satisfying: 0.015*Df≤Tc≤0.05*Df.

[0034] According to some embodiments of this application, the connection between the thin-walled segment and the first mounting part is constructed as a curve, the curve is composed of at least two arc segments, the curve is connected to the outer side of the thin-walled segment at point a, the curve is connected to the first mounting part at point e, and along the axial direction, the distance from point a to point e is Lwa, which satisfies: 0.1*Lc1≤Lwa≤0.3*Lc1.

[0035] According to some embodiments of this application, the curve has points b, c, and d. The distance from point a to point b is Lwb, the distance from point b to point c is Lwc, and the distance from point c to point d is Lwd, where Lwb = Lwc = Lwd = Lwa / 4. Along the radial direction of the rigid wheel, the distances from point b, c, d, and e to point a are Lrb, Lrc, Lrd, and Lre, respectively, where Lrb < Lrc < Lrd < Lre, satisfying: 0.1*Tc ≤ Lre ≤ 0.4*Tc, and Lrb + Lrc + Lrd ≤ Lre / 2.

[0036] According to some embodiments of this application, the flexible wheel further includes a cylinder, a diaphragm, and a flange. The external toothed portion is connected to the outer side of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, the flange is connected to the end of the diaphragm away from the cylinder, and the flange is fixedly connected to the outer bearing ring.

[0037] According to some embodiments of this application, along the axial direction, the external tooth portion includes a first tooth segment away from the flange portion and a second tooth segment near the flange portion. The diameter of the tip circle of the first tooth segment gradually decreases in the direction away from the flange portion, and the diameter of the tip circle of the second tooth segment gradually decreases in the direction toward the flange portion.

[0038] According to some embodiments of this application, the external tooth portion further includes a third tooth segment located between the first tooth segment and the second tooth segment, wherein the diameter of the tip circle of the third tooth segment is constant.

[0039] According to some embodiments of this application, along the axial direction, the effective width of the flexible wheel is Lf, the width of the external tooth is Lf1, the width of the first tooth segment is Lf2, the width of the second tooth segment is Lf4, and the width of the third tooth segment is Lf3, satisfying: 0.4*Lf≤Lf1≤0.6*Lf; 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

[0040] According to some embodiments of this application, the inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.3°≤α1≤1.0°, 0°≤β1≤0.4°, and β1<α1.

[0041] According to some embodiments of this application, the tooth root wall thickness of the flexure is Tf, the inner diameter of the flexure is Df, and the reduction ratio of the harmonic reducer is R, satisfying: 0.0043ln(R)-0.0061≤Tf / Df≤0.005ln(R)-0.0036.

[0042] According to some embodiments of this application, along the axial direction, the effective width of the flexible wheel is Lf, which satisfies: 0.45*Lf≤Lc≤0.65*Lf.

[0043] According to some embodiments of this application, the outer bearing ring includes a second mounting portion and a protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring is provided with a groove that is opposite to the protrusion. The groove has a first inner raceway and a second inner raceway at both ends along the axial direction. The first inner raceway and the first outer raceway are opposite to each other and form the first groove. The second inner raceway and the second outer raceway are opposite to each other and form the second groove.

[0044] According to some embodiments of this application, there is a gap between the protrusion and the bottom wall of the groove, and the first groove and the second groove are connected through the gap.

[0045] According to some embodiments of this application, the inner bearing ring includes a first ring body and a second ring body connected to each other. The first inner raceway is located outside the first ring body and close to the second ring body, and the second inner raceway is located outside the second ring body and away from the first ring body. The second ring body is connected to the rigid wheel.

[0046] According to some embodiments of this application, the outer side of the thin-walled segment abuts against the inner side of the second ring body; along the axial direction, the end of the second ring body away from the first ring body abuts against the end of the first mounting portion facing the thin-walled segment.

[0047] An industrial robot according to a fourth aspect of this application includes the harmonic reducer described in the above embodiments.

[0048] The industrial robot according to the embodiments of this application has at least the following beneficial effects:

[0049] The harmonic reducer using the third embodiment features a wave generator located inside the flex wheel, with the outer teeth of the flex wheel partially meshing with the inner teeth of the rigid wheel. Therefore, when the wave generator rotates, it drives the flex wheel and the rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the support bearing. The first groove is for mounting a first rolling element, and the second groove is for mounting a second rolling element. The first and second grooves are spaced apart along the axial direction of the wave generator. By providing two sets of rolling elements, the load-bearing capacity of the harmonic reducer can be effectively improved, enhancing the assembly efficiency between the bearing assembly, the rigid wheel, and the flex wheel while maintaining the overall compact structure. Since the rigid wheel includes a connected first mounting portion and an inner tooth portion, and the first mounting portion is located at the end of the inner tooth portion away from the inner bearing ring, the inner bearing ring can extend to the outer wall of the inner tooth portion, resulting in a relatively long overall length. Providing mounting holes on the inner bearing ring has minimal impact on the raceway, reducing the machining difficulty of the support bearing. Meanwhile, since the internal teeth protrude from the first mounting part, the internal teeth are designed with thin walls, which can generate elastic deformation to a certain extent. Therefore, without reducing the meshing depth between the internal and external teeth, the elastic deformation of the internal teeth is used to reduce the interference between them, thereby improving the load-bearing capacity of the harmonic reducer and reducing vibration and noise.

[0050] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0051] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0052] Figure 1 is a schematic cross-sectional view of the structure of a harmonic reducer according to an embodiment of this application;

[0053] Figure 2 is a partial cross-sectional view of the flexible wheel according to an embodiment of this application;

[0054] Figure 3 is a partial structural schematic diagram of a flexible wheel according to an embodiment of this application;

[0055] Figure 4 is an enlarged view of point A in Figure 1;

[0056] Figure 5 is a partial cross-sectional schematic diagram of the external teeth of an embodiment of this application;

[0057] Figure 6 is a partial cross-sectional schematic diagram of the external tooth portion according to an embodiment of this application;

[0058] Figure 7 is a schematic diagram of the structure of the inner bearing ring according to an embodiment of this application;

[0059] Figure 8 is an enlarged view of point B in Figure 7;

[0060] Figure 9 is a cross-sectional view of the outer bearing ring according to an embodiment of this application;

[0061] Figure 10 is an enlarged view of point C in Figure 9;

[0062] Figure 11 is a graph showing the relationship between the Tf / Df ratio and the stress at the root of the flexible gear tooth in one embodiment of this application.

[0063] Figure 12 is a graph showing the relationship between the L3 / Lc ratio and the overall weight and vibration acceleration of an embodiment of this application.

[0064] Figure 13 is a graph showing the relationship between the L1 / Lf ratio, the allowable torque of the support bearing, and the overall weight of the machine according to an embodiment of this application.

[0065] Figure 14 is a graph showing the relationship between the L2 / Lf ratio, the allowable torque of the support bearing, and the overall weight of the machine according to an embodiment of this application.

[0066] Figure 15 is a comparison diagram of the overturning moment stiffness before and after raceway modification in a harmonic reducer according to an embodiment of this application;

[0067] Figure 16 is a graph showing the relationship between the ratio of Db1 / Df in a harmonic reducer according to an embodiment of this application and the allowable torque of the bearing device and the weight of the whole machine.

[0068] Figure 17 is a graph showing the relationship between the ratio of Db2 / Df in a harmonic reducer according to an embodiment of this application and the allowable torque of the bearing device and the weight of the whole machine.

[0069] Figure 18 is a structural cross-sectional schematic diagram of a harmonic reducer according to an embodiment of this application;

[0070] Figure 19 is a partial cross-sectional schematic diagram of the flexible wheel and rigid wheel according to an embodiment of this application;

[0071] Figure 20 is a partial structural schematic diagram of a rigid wheel according to an embodiment of this application;

[0072] Figure 21 is an enlarged view of point B in Figure 3;

[0073] Figure 22 is an enlarged view of point A in Figure 18;

[0074] Figure 23 is a graph showing the relationship between the L3 / Lc ratio and the overall weight and vibration acceleration of an embodiment of this application;

[0075] Figure 24 is a graph showing the relationship between the L1 / Lf ratio, the allowable torque of the support bearing, and the overall weight of the machine according to an embodiment of this application.

[0076] Figure 25 is a graph showing the relationship between the Tf / Df ratio and the stress at the root of the flexible gear tooth in one embodiment of this application.

[0077] Reference numerals: Harmonic reducer 1000; Rigid wheel 100; Internal gear section 110; Thin-walled section 111; First mounting section 120; Curve 130; Flexible wheel 200; External gear section 210; First tooth section 211; First inclined surface 2111; Second inclined surface 2112; Second tooth section 212; Third inclined surface 2121; Fourth inclined surface 2122; Third tooth section 213; Cylindrical section 220; Diaphragm section 230; Flange section 240; Wave generator 300; Cam 310; Flexible bearing 320; Support bearing 400; Outer bearing ring 410; Second mounting section 411; Protrusion 412; First outer raceway 413; Second arc section 4131; Second shaping section 4132; Second curve 4133; Second outer raceway 414; Inner bearing ring 420; Protrusion 421; Groove 422; First inner raceway 423; First arc segment 4231; First shaping section 4232; First curve 4233; Second inner raceway 424; First ring body 425; Second ring body 426; Mounting hole 427; First groove 430; First rolling element 431; Second groove 440; Second rolling element 441; Oil seal 500. Detailed Implementation

[0078] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0079] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and 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 of this application.

[0080] In the description of this application, "multiple" refers to two or more. The use of "first" and "second" is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or the order in which the technical features are indicated.

[0081] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0082] Referring to Figures 1 and 2, a harmonic reducer 1000 according to an embodiment of this application includes a flexible wheel 200, a rigid wheel 100, and a wave generator 300. The flexible wheel 200 is coaxially mounted inside the rigid wheel 100, and the wave generator 300 is coaxially mounted in the inner hole of the flexible wheel 200. The flexible wheel 200 includes a cylindrical portion 220, a diaphragm portion 230, and a flange portion 240. The cylindrical portion 220 is located at the end of the flexible wheel 200 near the rigid wheel 100. The diaphragm portion 230 is connected to the end of the cylindrical portion 220 away from the rigid wheel 100 and extends radially towards the cylindrical portion 220. The flange portion 240 is connected to the outer periphery of the diaphragm portion 230. The cylindrical portion 220 of the flexible wheel 200 is provided with a flexible external tooth portion 210. The external tooth portion 210 is a structure that bulges radially outward from the cylindrical portion 220. The external tooth portion 210 is not formed in the inner hole of the flexible wheel 200, but is formed on the outer wall of the cylindrical portion 220. The rigid wheel 100 is provided with a rigid internal tooth 110, and an external tooth 210 engages with the internal tooth 110, forming a meshing gap between the external tooth 210 and the internal tooth 110.

[0083] In the embodiments of this application, the wave generator 300 is interference-fitted into the inner bore of the flexible wheel 200. The wave generator 300 is configured to partially mesh with the outer tooth portion 210 and the inner tooth portion 110 when rotating. Partial meshing means that the outer tooth portion 210 of the flexible wheel 200 deforms in the circumferential direction, and the deformed part of the outer tooth portion 210 partially meshes with the corresponding position of the inner tooth portion 110. That is, the meshing position of the inner tooth portion 110 and the outer tooth portion 210 moves cyclically in the circumferential direction. When the wave generator 300 is inserted into the inner bore of the flexible wheel 200, it forces the flexible wheel 200 to undergo elastic deformation and become elliptical. During the operation of the harmonic reducer 1000, the wave generator 300 rotates at high speed, causing the flexible wheel 200 to undergo repeated deformation. This causes the outer tooth 210 of the flexible wheel 200 to mesh with the inner tooth 110 of the rigid wheel 100. The meshing position of the outer tooth 210 and the inner tooth 110 moves circumferentially along the rotation axis of the wave generator 300, thereby achieving relative deceleration between the flexible wheel 200 and the rigid wheel 100. The wave generator 300 includes a flexible bearing 320 and a cam 310. The flexible bearing 320 is sleeved on the outside of the cam 310, and the cam 310 has a mounting position for connecting a motor or other drive device.

[0084] Referring to FIG1, a harmonic reducer 1000 according to an embodiment of the present application further includes a support bearing 400, which is configured to enable the rigid wheel 100 and the flexible wheel 200 to rotate relative to each other. The support bearing 400 includes a first rolling element 431, a second rolling element 441, an outer bearing ring 410, and an inner bearing ring 420 disposed within the outer bearing ring 410. An annular first groove 430 and an annular second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 along the axial direction of the wave generator 300. The first groove 430 is located on the side away from the rigid wheel 100, and the second groove 440 is located on the side closer to the rigid wheel 100 and is spaced apart from the first groove 430. That is, the first groove 430 is located on the left side of the harmonic reducer 1000, and the second groove 440 is located on the right side of the harmonic reducer 1000. Multiple first rolling elements 431 are provided and installed in the first groove 430; multiple second rolling elements 441 are provided and installed in the second groove 440. The inner bearing ring 420 is fixedly connected to the rigid wheel 100, and the outer bearing ring 410 is fixedly connected to the flange 240 of the flexible wheel 200. The fixed connection can be achieved through fasteners (such as screws, bolts, pins, etc.), or by snap-fitting, adhesive bonding, or other methods. Therefore, the cooperation of the first rolling elements 431, the second rolling elements 441, the inner bearing ring 420, and the outer bearing ring 410 facilitates the relative rotation of the flexible wheel 200 and the rigid wheel 100.

[0085] By employing two sets of rolling elements, consisting of multiple first rolling elements 431 and multiple second rolling elements 441, the load-bearing capacity of the bearing assembly can be improved compared to the single-row crossed roller bearings in related technologies. Furthermore, the structure of the inner bearing ring 420 and the outer bearing ring 410 facilitates the assembly of the harmonic reducer 1000 and makes it easier to adapt to different loads. It is understood that the first rolling element 431 can be a sphere, or a cylindrical or conical shape; the second rolling element 441 can also be a sphere, or a cylindrical or conical shape, etc., and is not specifically limited here. In addition, in this embodiment, the first rolling elements 431 and the second rolling elements 441 can be made of metal materials such as steel.

[0086] Flexible gears 200 of the same specification have the same inner diameter and basically the same external dimensions. When the reduction ratio of the harmonic reducer 1000 is different, the number of teeth and the module of the flexible gear 200 are usually different, resulting in different stresses when the flexible gear 200 deforms. In order to reduce the stress on the flexible gear 200 during deformation and simplify the design of flexible gears 200 of the same specification but different reduction ratios, as shown in Figures 1 and 3, in the embodiments of this application, the tooth root wall thickness of the flexible gear 200 is Tf. The tooth root wall thickness Tf refers to the distance between the tooth root of the outer tooth portion 210 and the inner hole wall of the flexible gear 200 along the radial direction of the flexible gear 200. The inner diameter of the flexible wheel 200 is Df, and the reduction ratio of the harmonic reducer 1000 is R, satisfying: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036, where the reduction ratio R can be obtained from the parameters marked on the nameplate of the harmonic reducer 1000.

[0087] Referring to Figure 11, the horizontal axis of the graph in Figure 11 represents the value of Tf / Df, and the vertical axis represents the root stress of the flexure 200. It can be seen from the graph that as the value of Tf / Df gradually increases, the root stress on the flexure 200 first decreases and then increases, with a minimum value. Therefore, for flexures 200 of the same specification but with different reduction ratios, using the natural logarithm function Ln(R) to eliminate the influence of the reduction ratio R only requires ensuring that the value of Tf / Df is limited to the ranges of 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036. This effectively reduces the stress on the flexure 200, simplifies its design, improves production efficiency, and is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R, reducing the stress on the flexure 200 during deformation. Meanwhile, compared with the flexible wheel in related technologies, the tooth root wall thickness Tf of the flexible wheel 200 in this embodiment is increased, which can effectively improve the load-bearing capacity and torsional stiffness of the harmonic reducer 1000.

[0088] Referring to Figure 2, in this embodiment of the application, along the axial direction of the wave generator 300, the effective width of the flexible wheel 200 is Lf, which refers to the minimum distance between the end face of the cylindrical portion 220 away from the flange portion 240 and the flange portion 240. The width of the internal gear portion 110 is Lc, which refers to the maximum length of the internal gear portion 110 along the axial direction, for example, the distance between the two farthest end faces of the rigid wheel 100 along the axial direction. The relationship between Lf and Lc satisfies: 0.45*Lf≤Lc≤0.65*Lf. The value of Lc can be 0.45*Lf, 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, or 0.65*Lf. When Lc is less than 0.45*Lf, meaning the maximum length of the internal gear 110 is short, the contact area between the internal gear 110 and the external gear 210 decreases, increasing contact stress and reducing the load-bearing capacity of the harmonic reducer 1000. When Lc is greater than 0.65*Lf, meaning the maximum length of the internal gear 110 is large, it occupies too much space and has too large a strength margin, which is not conducive to the miniaturization design of the harmonic reducer 1000. Therefore, rationally designing the maximum length Lc and Lf of the internal gear 110 can effectively increase the contact area between the internal gear 110 and the external gear 210, reduce contact stress, improve the load-bearing capacity of the harmonic reducer 1000, and also facilitate the miniaturization design of the harmonic reducer 1000.

[0089] It should be noted that the inner hole of the flexible wheel 200 is circular when it is not installed with the wave generator 300. After the flexible wheel 200 and the wave generator 300 are assembled, the outer tooth 210 of the flexible wheel 200 becomes elliptical. Due to the structural relationship of the flexible wheel 200, the deformation of different sections of the outer tooth 210 along the axial direction is different, and the deformation is greater closer to the opening of the cylinder 220. Generally, the meshing state of the middle tooth section of the outer tooth 210 along the axial direction is optimal. The tooth section near the flange 240 is prone to interference with the tooth tip of the inner tooth 110 of the rigid wheel 100 or the clearance is too small, resulting in abnormal friction and wear and noise. The tooth section away from the flange 240 is prone to interference with the tooth root or middle part of the inner tooth 110 of the rigid wheel 100, which also results in abnormal friction and wear and noise.

[0090] To mitigate the interference between the external gear portion 210 and the internal gear portion 110, which can lead to friction, wear, and noise, as shown in Figure 4, in this embodiment of the application, the rigid wheel 100 further includes a first mounting portion 120. The first mounting portion 120 is annular and connected to the inner bearing ring 420. The connection between the first mounting portion 120 and the inner bearing ring 420 can be achieved using fasteners, such as screws, bolts, or pins. The internal gear portion 110 is connected to the inner side of the first mounting portion 120, and the connection can be integrally formed. Along the axial direction of the wave generator 300, the width of the internal gear portion 110 is greater than the width of the first mounting portion 120. It is understood that because the width of the internal gear portion 110 is greater than the width of the first mounting portion 120, a portion of the structure of the internal gear portion 110 will protrude axially from the first mounting portion 120, allowing the internal gear portion 110 to undergo slight elastic deformation. When the flexible gear 200 is subjected to a large load, the slight elastic deformation of the internal tooth portion 110 reduces the frictional loss between the flexible gear 200 and the rigid gear 100, thereby increasing the service life of the flexible gear 200. Simultaneously, compared to the rigid gear in related technologies, the increased width of the internal tooth portion 110 in this embodiment increases the contact area with the external tooth portion 210, reduces the meshing surface pressure, and improves the load-bearing capacity of the harmonic reducer 1000.

[0091] Referring again to Figure 4, in this embodiment of the application, the portion of the internal gear 110 protruding axially from the first mounting portion 120 abuts against the inner side of the inner bearing ring 420. Therefore, the inner bearing ring 420 supports the internal gear 110, preventing excessive force on the internal gear 110 and thus avoiding large-angle bending deformation, thereby improving the reliability of the rigid wheel 100. One end of the inner bearing ring 420 along the axial direction is provided with a protrusion 421, which protrudes towards the first mounting portion 120, and the inner side of the protrusion 421 abuts against the outer side of the first mounting portion 120. It is understood that providing the protrusion 421 can play a positioning role in the installation of the rigid wheel 100. Simultaneously, the protrusion 421 also facilitates the installation of the oil seal 500 between the inner bearing ring 420 and the outer bearing ring 410. The oil seal 500 is annular and concentrically positioned with the outer bearing ring 410. The outer side of the oil seal 500 is interference-fitted with the inner hole of the outer bearing ring 410, and the inner hole of the oil seal 500 is sealed with the outer wall of the protrusion 421 to improve the sealing effect. When the inner bearing ring 420 and the oil seal 500 rotate relative to each other, they can also form a radial contact seal, thereby effectively preventing the lubricating material in the first groove 430 and the second groove 440 from overflowing into the rigid wheel 100.

[0092] Referring again to Figure 4, in this embodiment of the application, along the axial direction of the harmonic reducer 1000, the first mounting portion 120 is connected to the end of the internal gear portion 110 that is away from the inner bearing ring 420, that is, the first mounting portion 120 is connected to the right end of the internal gear portion 110. Therefore, the internal gear portion 110 is designed with a thin wall, which is beneficial for the internal gear portion 110 to generate a certain degree of elastic deformation. This can reduce meshing interference without reducing the meshing depth between the internal gear portion 110 and the external gear portion 210, reduce the frictional loss between the flexible gear 200 and the rigid gear 100, and reduce the vibration and noise of the harmonic reducer 1000 during operation, thereby improving the service life of the flexible gear 200.

[0093] Referring to Figures 1 and 2, in the embodiments of this application, along the axial direction of the wave generator 300, the first rolling element 431 is located between the diaphragm 230 and the internal gear portion 110, which can improve the compactness of the harmonic reducer 1000 and reduce its volume. The width of the internal gear portion 110 is Lc, and the minimum distance between the end face of the internal gear portion 110 facing the first rolling element 431 and the center of the second rolling element 441 is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc. For example, the value of L3 can be -0.1*Lc, -0.05*Lc, 0.1*Lc, 0.2*Lc, etc. When L3>0, the center of the second rolling element 441 is located between the two end faces of the external gear portion 210 along the axial direction. When L3 < 0, the center of the second rolling element 441 is located between the external tooth portion 210 and the diaphragm portion 230, that is, the center of the second rolling element 441 is located between the end face of the external tooth portion 210 facing the diaphragm portion 230 and the end face of the diaphragm portion 230 facing the external tooth portion 210. It should be noted that the end of the rigid wheel 100 facing the flange portion 240 is the inner end face, and the end facing away from the flange portion 240 is the outer end face. "The center of the second rolling element 441 is located between the two axial end faces of the external tooth portion 210" means that the center of the second rolling element 441 is located on the right side of the outer end face of the rigid wheel 100; "The center of the second rolling element 441 is located between the external tooth portion 210 and the diaphragm portion 230" means that the center of the second rolling element 441 is located on the left side of the outer end face of the rigid wheel 100.

[0094] It should also be noted that -0.1*Lc≤L3≤0.2*Lc is equivalent to -0.1≤L3 / Lc≤0.2. Referring to Figure 12, the horizontal axis represents the value of L3 / Lc, the left vertical axis represents the total weight of the harmonic reducer 1000, and the right vertical axis represents the vibration acceleration of the harmonic reducer 1000. Vibration acceleration refers to the acceleration generated by vibration phenomena caused by various internal and external factors during the operation of the reducer. Vibration acceleration reflects the stability and smoothness of the reducer during dynamic operation. A smaller vibration acceleration means that the harmonic reducer 1000 is more stable and smoother during operation, which helps to reduce wear and energy loss, and improve the overall performance and lifespan of the reducer. The total weight includes the weight of the rigid wheel 100, the flexible wheel 200, the wave generator 300, and the support bearing 400.

[0095] As shown in Figure 12, as the value of L3 / Lc gradually increases, the overall weight of the harmonic reducer 1000 initially remains constant and then gradually increases, while the vibration acceleration gradually decreases. Therefore, the design of the harmonic reducer 1000 requires a lightweight overall machine and low vibration acceleration. When the value of L3 / Lc is less than -0.1, although the overall weight is light, the vibration acceleration is relatively large, and the harmonic reducer 1000 is prone to vibration and noise during operation, resulting in poor operational stability. When the value of L3 / Lc is greater than 0.2, although the vibration acceleration is lower, the overall weight increases significantly, leading to increased material costs. Therefore, by rationally designing the value of L3 / Lc to be within the range of -0.1 to 0.2, the overall weight can be reduced while keeping the vibration acceleration at a low value, thereby reducing production costs and improving the operational stability of the harmonic reducer 1000.

[0096] Referring to FIG5, in an embodiment of this application, the external toothed portion 210 includes a plurality of protruding teeth arranged circumferentially along the flexible wheel 200 and extending outward. The plurality of protruding teeth includes a first tooth segment 211, a second tooth segment 212, and a third tooth segment 213 extending axially. From the external toothed portion 210 to the flange portion 240, i.e., from right to left in FIG5, the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 are connected sequentially. The tip circle diameter of the first tooth segment 211 gradually decreases in the direction away from the flange portion 240, and the tip circle diameter of the second tooth segment 212 gradually decreases in the direction towards the flange portion 240. That is, the first tooth segment 211 and the second tooth segment 212 adopt a tooth-direction modification scheme, and the tooth height of the first tooth segment 211 and the second tooth segment 212 gradually decreases in the direction away from the third tooth segment 213. The tooth height refers to the height in the radial direction. For example, the tooth tips of the first tooth segment 211 and the second tooth segment 212 can be inclined along a straight line, or be an outwardly convex arc, an inwardly concave arc, etc. By setting the tooth height of the first tooth segment 211 and the second tooth segment 212 to gradually decrease, the interference between the tooth tips of the first tooth segment 211 and the second tooth segment 212 and the internal tooth portion 110 can be effectively reduced, thereby improving the service life of the flexible gear 200.

[0097] Referring again to Figure 5, in the embodiment of this application, the diameter of the tip circle of the third tooth segment 213 is constant, that is, the tooth height of the third tooth segment 213 remains unchanged. Because the flexible wheel 200, under the action of the wave generator 300, has an elliptical shape after the cylindrical portion 220 becomes elliptical, the motion trajectory of the outer tooth portion 210 is different at different cross-sections. The state is optimal in the middle part of the outer tooth portion 210, that is, the third tooth segment 213, where interference is less likely to occur. However, interference with the inner tooth portion 110 is more likely to occur at the two ends of the outer tooth portion 210 along the axial direction. Therefore, by designing the tooth height of the first tooth segment 211 and the tooth height of the second tooth segment 212 to gradually decrease in the direction away from the third tooth segment 213, the interference between the tip of the first tooth segment 211 and the tip of the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced.

[0098] Referring to Figures 2 and 6, in the embodiments of this application, along the direction parallel to the rotation axis of the wave generator 300, the effective width of the flexible wheel 200 is Lf, and the tooth width of the external tooth portion 210 is Lf1, satisfying: 0.4*Lf≤Lf1≤0.6*Lf. For example, the value of Lf1 can be 0.4*Lf, 0.45*Lf, 0.5*Lf, 0.55*Lf, or 0.6*Lf. The width of the first tooth segment 211 is Lf2, satisfying: 0.2*Lf1≤Lf2≤0.35*Lf1. For example, the value of Lf2 can be 0.2*Lf1, 0.23*Lf1, 0.24*Lf1, 0.25*Lf1, 0.3*Lf1, or 0.35*Lf1. The width of the third tooth segment 213 is Lf3, satisfying: 0.35*Lf1≤Lf3≤0.45*Lf1. For example, the value of Lf3 can be 0.35*Lf1, 0.38*Lf1, 0.39*Lf1, 0.40*Lf1, 0.42*Lf1, or 0.45*Lf1. The width of the second tooth segment 212 is Lf4, satisfying: 0.25*Lf1≤Lf4≤0.4*Lf1. For example, the value of Lf4 can be 0.25*Lf1, 0.28*Lf1, 0.3*Lf1, 0.35*Lf1, 0.38*Lf1, or 0.4*Lf1.

[0099] Understandably, the widths of the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 affect the meshing effect with the internal tooth portion 110. When Lf1 is less than 0.4*Lf, the tooth width of the external tooth portion 210 is shorter, reducing the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, thus worsening the stability during meshing. When Lf1 is greater than 0.6*Lf, the tooth width of the external tooth portion 210 is longer, increasing the volume of the harmonic accelerator and hindering compact design. When Lf2 is less than 0.2*Lf1, meaning the width of the first tooth segment 211 is smaller, interference with the internal tooth portion 110 is more likely. When Lf2 is greater than 0.4*Lf1, meaning the width of the first tooth segment 211 is larger, the width of the third tooth segment 213 needs to be shortened accordingly while keeping the width of the external tooth portion 210 constant, resulting in a reduction in the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, further worsening the stability during meshing. When Lf3 is less than 0.35*Lf1, meaning the width of the third tooth segment 213 is small, the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110 will decrease, resulting in poorer stability during meshing. When Lf3 is greater than 0.45*Lf1, with the width of the external tooth portion 210 remaining constant, the widths of the first tooth segment 211 and the second tooth segment 212 need to be reduced accordingly, which can easily lead to interference with the internal tooth portion 110 at the first tooth segment 211 and the second tooth segment 212. When Lf4 is less than 0.25*Lf1, meaning the width of the second tooth segment 212 is small, it is easy to interfere with the internal tooth portion 110. When Lf4 is greater than 0.45*Lf1, meaning the width of the second tooth segment 212 is large, with the width of the external tooth portion 210 remaining constant, the width of the third tooth segment 213 needs to be shortened accordingly, resulting in a decrease in the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110, and worsening stability during meshing.

[0100] Therefore, by rationally designing the ratio of the tooth width of the external tooth section 210 to the effective width of the flexible gear 200 to be between 0.4 and 0.6, the ratio of the width of the first tooth segment 211 to the width of the external tooth section 210 to be between 0.2 and 0.35, the ratio of the width of the third tooth segment 213 to the width of the external tooth section 210 to be between 0.35 and 0.45, and the ratio of the width of the second tooth segment 212 to the width of the external tooth section 210 to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the external tooth section 210 and the internal tooth section 110, while also reducing the interference between the external tooth section 210 and the internal tooth section 110, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear 200.

[0101] Referring to FIG6, in the embodiment of this application, the inclination angle of the first tooth segment 211 is α1, and the inclination angle of the second tooth segment is β1. It should be noted that the inclination angle α1 of the first tooth segment 211 refers to the fact that the tooth tip of the first tooth segment 211 is constructed as a first inclined surface 2111, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle α1 between the first inclined surface 2111 and the rotation axis. The inclination angle β1 of the second tooth segment refers to the fact that the tooth tip of the second tooth segment 212 is constructed as a second inclined surface 2112, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle β1 between the second inclined surface 2112 and the rotation axis.

[0102] The inclination angle α1 of the first tooth segment 211 and the inclination angle β1 of the second tooth segment satisfy the following conditions: 0.3°≤α1≤1°, 0.3°≤β1≤1°, and β1≥α1. For example, the value of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°; and the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α1 is less than 0.3°, that is, the inclination angle of the first inclined surface 2111 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α1 is greater than 1°, it is easy to reduce the effective area when the first tooth segment 211 and the internal tooth portion 110 mesh, thus leading to a decrease in meshing stability. When β1 is less than 0.3°, that is, the inclination angle of the second inclined surface 2112 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β1 is greater than 1°, it can easily lead to a reduction in the effective area when the second tooth segment 212 and the internal tooth portion 110 mesh, thereby resulting in poor meshing stability.

[0103] It is understandable that when the wave generator 300 is embedded in the inner hole of the cylindrical part 220, the outer wall of the cylindrical part 220 will be tilted, i.e., an angle will be formed. Since the second tooth segment 212 is closer to the flange part 240 than the first tooth segment 211, the second tooth segment 212 is more likely to interfere with the inner tooth part 110. Therefore, by setting the inclination angle of the second inclined surface 2112 to be greater than the inclination angle of the first inclined surface 2111, the interference between the second tooth segment 212 and the inner tooth part 110 can be effectively reduced or avoided, and the contact area between the second tooth segment 212 and the inner tooth part 110 can be increased to improve the stability during power transmission.

[0104] Referring again to Figure 6, in this embodiment of the application, to further reduce interference between the external tooth portion 210 and the internal tooth portion 110, a third inclined surface 2121 is provided between two adjacent first tooth segments 211. The third inclined surface 2121 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. A fourth inclined surface 2122 is provided between two adjacent second tooth segments 212. The fourth inclined surface 2122 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. The inclination angle of the third inclined surface 2121 can be the same as or different from that of the first inclined surface 2111, and the inclination angle of the fourth inclined surface 2122 can be the same as or different from that of the second inclined surface 2112. This effectively reduces or avoids interference between the tooth tip of the internal tooth portion 110 and the tooth root of the external tooth portion 210, thereby reducing tooth surface friction and wear and extending the life of the flexible gear 200.

[0105] Referring again to Figure 6, in this embodiment, the inclination angle of the third inclined surface 2121 is α2, satisfying: 0.3°≤α2≤1°. For example, the value of α2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α2 is less than 0.3°, that is, the inclination angle of the third inclined surface 2121 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α2 is greater than 1°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent teeth. Therefore, by reasonably designing the sizes of α1 and α2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0106] Referring again to Figure 6, in this embodiment, the inclination angle of the fourth inclined surface 2122 is β2, satisfying: 0.3°≤β2≤1°. For example, the value of β2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When β2 is less than 0.3°, that is, the inclination angle of the fourth inclined surface 2122 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β2 is greater than 1°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent protrusions. Therefore, by reasonably designing the sizes of β1 and β2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0107] Table 1: Comparison of tooth surface contact area under different schemes

[0108] For example, referring to Table 1 above, Scheme 1 is a scheme in the related art, where Lc = 0.42 * Lf, Lf1 = 0.36 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 2 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 3 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the first tooth segment 211 and the second tooth segment 212 of the external tooth portion 210 adopt a modification scheme. As can be seen from Table 1 above, designing Lc = 0.55 * Lf and Lf1 = 0.5 * Lf can increase the tooth surface contact area by 18.3%, and further adding a modification scheme on this basis increases the improvement by 32.6% compared to Scheme 1. The larger the contact area of ​​the tooth surface, the smaller the contact stress, and the greater the load-bearing capacity of the harmonic reducer 1000.

[0109] Referring to Figures 1 and 2, in the embodiments of this application, the effective width of the flexure 200 along the axial direction is Lf. The effective width of the flexure 200 refers to the minimum distance between the end face of the cylinder 220 facing away from the flange 240 and the flange 240. The maximum distance between the outer bearing ring 410 abutting against the end wall of the flange 240 and the center of the first rolling element 431 is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf. This formula is equivalent to 0.2≤L1 / Lf≤0.28, for example, the value of L1 / Lf can be 0.2, 0.22, 0.24, 0.26, 0.28, etc. Referring to Figure 13, the horizontal axis in Figure 13 represents the value of L1 / Lf, the left vertical axis represents the allowable torque of the supporting bearing 400, and the right vertical axis represents the overall weight of the harmonic reducer 1000. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use, and the total weight includes the weight of the rigid wheel 100, flexible wheel 200, wave generator 300, and support bearing 400. Referring to Figure 13, when L1 / Lf is less than 0.2, the overall weight of the harmonic reducer 1000 is relatively light, but the allowable torque decreases rapidly, failing to meet usage requirements. When L1 / Lf is greater than 0.28, the allowable torque is relatively large, but the overall weight increases rapidly, also failing to meet usage requirements. Therefore, by balancing the overall weight of the harmonic reducer 1000 and the allowable torque requirements, setting the L1 / Lf ratio between 0.2 and 0.28 can simultaneously meet the requirements for maximum overturning torque and overall weight.

[0110] Referring to Figures 1 and 2, in the embodiments of this application, the effective width of the flexible wheel 200 along the axial direction is Lf. Parallel to the axial direction, the maximum distance between the center of the first rolling element 431 and the center of the second rolling element 441 is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf. This formula is equivalent to 0.24≤L2 / Lf≤0.34, where L2 / Lf can be 0.24, 0.25, 0.3, 0.31, or 0.34. Referring to Figure 14, the horizontal axis represents the value of L2 / Lf, the left vertical axis represents the allowable torque of the support bearing 400, and the right vertical axis represents the main body length of the harmonic reducer 1000. The main body length is the maximum axial dimension of the assembly of the rigid wheel 100, the flexible wheel 200, and the support bearing 400. The definition of the allowable torque is the same as in the above embodiments and will not be explained in detail in subsequent embodiments. When L2 / Lf is less than 0.24, the main body length of the harmonic reducer 1000 remains basically unchanged, but the allowable torque decreases rapidly, failing to meet the usage requirements. When L2 / Lf is greater than 0.34, the allowable torque shows a significant downward trend, and the main body length increases rapidly, also failing to meet the usage requirements. Therefore, by balancing the requirements of the main body length and allowable torque of the harmonic reducer 1000, setting the L2 / Lf ratio between 0.2 and 0.28 can simultaneously meet the requirements of the maximum overturning moment and the main body length.

[0111] Referring to Figures 7, 8, 9, and 10, in the embodiments of this application, the outer bearing ring 410 includes a second mounting portion 411 and a protrusion 412 connected to the inner side of the second mounting portion 411. The protrusion 412 has a first outer raceway 413 and a second outer raceway 414 respectively, which are opposite to each other, at both ends along the axial direction. The protrusion 412 enhances the structural strength of the first outer raceway 413 and the second outer raceway 414, effectively reducing their deformation, and also limits the movement of the first rolling element 431 and the second rolling element 441, preventing them from contacting each other. The outer side of the inner bearing ring 420 has a groove 422 opposite to the protrusion 412. The two ends of the groove 422 along the axial direction are a first inner raceway 423 and a second inner raceway 424. The first inner raceway 423 and the first outer raceway 413 are arranged opposite each other to form a first groove 430, and the second inner raceway 424 and the second outer raceway 414 are arranged opposite each other to form a second groove 440. This arrangement facilitates the installation of the first rolling element 431 and the second rolling element 441, improves assembly efficiency, and allows the first rolling element 431 and the second rolling element 441 to rotate smoothly, thus improving the stability of the support bearing 400 during operation.

[0112] Referring to FIG4, in the embodiment of this application, there is a gap between the protrusion 412 and the bottom wall of the groove 422, and the first groove 430 and the second groove 440 are connected through the gap. It can be understood that by setting the first groove 430 and the second groove 440 to be connected through the gap, it is beneficial for lubricating oil to flow in the first groove 430 and the second groove 440, thereby lubricating the first rolling element 431 and the second rolling element 441, improving the smoothness and service life of the first rolling element 431 and the second rolling element 441 during rolling.

[0113] Referring to FIG4, in an embodiment of this application, the inner bearing ring 420 includes a first ring body 425 and a second ring body 426 connected together. The first ring body 425 and the second ring body 426 are arranged from left to right and are connected by fasteners. A step is provided on the side of the first ring body 425 facing the second ring body 426, and the second ring body 426 is positioned and connected to the step. The step serves a positioning function, thereby facilitating the connection between the first ring body 425 and the second ring body 426. A first inner raceway 423 is located outside the first ring body 425 and close to the second ring body 426, and a second inner raceway 424 is located outside the second ring body 426 and away from the first ring body 425. The second ring body 426 is connected to the rigid wheel 100. By designing the inner bearing ring 420 with the first ring body 425 and the second ring body 426 connected, the installation of the first rolling element 431 and the second rolling element 441 is facilitated, reducing assembly difficulty.

[0114] Referring to Figure 8, in the embodiment of this application, within the cross-section passing through the rotation axis of the wave generator 300, the outer contour line of the first inner raceway 423 is a first curve 4233. The first curve 4233 includes a first circular arc segment 4231 and a first shaping segment 4232, where the first shaping segment 4232 is non-circular. The radius of the first circular arc segment 4231 is Ri, and the maximum cross-sectional diameter of the first rolling element 431 is Db1. A coordinate system is established with the center of the first circular arc segment 4231 as the origin. The X-axis is parallel to the rotation axis and points away from the second rolling element 441, and the Y-axis is perpendicular to the X-axis and points towards the rotation axis. The first curve 4233 satisfies the equation:

[0115] ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi;

[0116] ρi = Ri, when θ1 > βi;

[0117] Where Ri = (0.505~0.515)*Db1, ki = 0.002~0.004, βi = 20°-30°, for example, βi takes values ​​of 20°, 25°, and 30°. It should be noted that θ1 is the central angle of the first curve 4233 relative to the center point of the coordinate system.

[0118] The embodiments of this application design the first curve 4233 so that when the first inner raceway 423 is subjected to a large overturning moment, the first rolling element 431 and the first inner raceway 423 have multi-point contact, which increases the contact position and contact area, reduces the contact stress, and is significantly better than the single-point contact between the first rolling element 431 and the first inner raceway 423 in the related art (before modification).

[0119] For example, when the support bearing 400 is under stress, both the first rolling element 431 and the first inner raceway 423 deform. Before the deformation, the first rolling element 431 and the first inner raceway 423 have a single-point contact at approximately 40°; however, after the deformation, the first rolling element 431 and the first inner raceway 423 not only have contact at approximately 40°, but also have contact between 10° and 20°. Therefore, the contact area between the first rolling element 431 and the first inner raceway 423 is larger, which can reduce the contact stress between the first rolling element 431 and the first inner raceway 423, thereby improving the overall overturning moment and overturning moment rigidity of the support bearing 400.

[0120] Figure 15 is a comparison diagram of the overturning moment stiffness of the first inner raceway 423 in a harmonic reducer 1000 according to an embodiment of this application before and after modification. Referring to Figure 15, after modification of the first inner raceway 423, when the support bearing 400 bears a large torque (greater than Nm as shown in Figure 15), the angle at which the overturning moment is generated becomes smaller. According to the equation Overturning moment stiffness = Overturning moment / Angle at which the overturning moment is generated, when the overturning moment is constant, the smaller the angle at which the overturning moment is generated, the greater the overturning moment stiffness. Therefore, after modification of the first inner raceway 423 according to the above equation in the embodiment of this application, the overturning moment stiffness is improved to varying degrees, even reaching 20%.

[0121] It is understood that in this embodiment, the first inner raceway 423 and the second inner raceway 424 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. The outer contour of the second inner raceway 424 is the third curve. The third curve and the first curve 4233 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. Therefore, the equation of the first curve 4233 can be used for understanding. To avoid repetition, it will not be described again here.

[0122] Referring to Figure 10, in the embodiment of this application, within the cross-section passing through the rotation axis of the wave generator 300, the outer contour line of the first outer raceway 413 is a second curve 4133. The second curve 4133 includes a second arc segment 4131 and a second shaping segment 4132, where the second shaping segment 4132 is non-circular. The radius of the second arc segment 4131 is Ro, and the maximum cross-sectional diameter of the first rolling element 431 is Db1. A coordinate system is established with the center of the second arc segment 4131 as the origin. The X-axis is parallel to the rotation axis and points in the direction of the second rolling element 441, and the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis. The second curve 4133 satisfies the equation:

[0123] ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo;

[0124] ρo=Ro, when θ2>βo;

[0125] Where Ro = (0.505~0.515)*Db1, ko = 0.002~0.004, βo = 20°-30°, for example, βo takes values ​​of 20°, 25°, and 30°. It should be noted that θ2 is the central angle of the first curve 4233 relative to the center point of the coordinate system.

[0126] The embodiments of this application design the second curve 4133 so that when the first outer raceway 413 is subjected to a large overturning moment, the first rolling element 431 and the first outer raceway 413 have multi-point contact, which increases the contact position and contact area, reduces the contact stress, and is significantly better than the single-point contact between the first rolling element 431 and the first outer raceway 413 in the related art (before modification).

[0127] For example, when the support bearing 400 is under stress, both the first rolling element 431 and the first outer raceway 413 deform. Before the deformation, the first rolling element 431 and the first outer raceway 413 have a single-point contact at approximately 40°; however, after the deformation, the first rolling element 431 and the first outer raceway 413 not only have contact at approximately 40°, but also have contact between 10° and 20°. Therefore, the contact area between the first rolling element 431 and the first outer raceway 413 is larger, which can reduce the contact stress between the first rolling element 431 and the first outer raceway 413, thereby improving the overall overturning moment and overturning moment rigidity of the support bearing 400.

[0128] Figure 15 is a comparison diagram of the overturning moment stiffness of the first outer raceway 413 before and after modification in a harmonic reducer 1000 according to an embodiment of this application. Referring to Figure 15, after modification of the first outer raceway 413, when the support bearing 400 bears a large torque (greater than 600 N·m as shown in Figure 15), the angle at which the overturning moment is generated becomes smaller. According to the equation Overturning moment stiffness = Overturning moment / Angle at which the overturning moment is generated, when the overturning moment is constant, the smaller the angle at which the overturning moment is generated, the greater the overturning moment stiffness. Therefore, after modification of the first outer raceway 413 according to the above equation in the embodiment of this application, the overturning moment stiffness is improved to varying degrees, even reaching 20%.

[0129] It is understood that in this embodiment, the first outer raceway 413 and the second outer raceway 414 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. The outer contour of the second outer raceway 414 is the fourth curve. The fourth curve and the second curve 4133 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. Therefore, the equation of the second curve 4133 can be used for understanding. To avoid repetition, it will not be described again here.

[0130] Referring to Figure 1, in the embodiment of this application, the inner diameter of the flexible wheel 200 is Df, which is also the inner diameter of the cylindrical portion 220. The maximum cross-sectional diameter of the first rolling element 431 is Db1, satisfying: 0.07*Df≤Db1≤0.13*Df. This formula is equivalent to 0.07≤Db1 / Df≤0.13, where the value of Db1 / Df can be 0.07, 0.09, 0.1, 0.12, or 0.13. Figure 16 is a graph showing the relationship between the ratio of Db1 to Df in a harmonic reducer 1000 according to an embodiment of this application, the allowable torque of the bearing device, and the overall weight. When Db1 / Df is less than 0.07, the overall weight of the harmonic reducer 1000 remains basically unchanged, but the allowable torque decreases rapidly, which cannot meet the usage requirements. When Db1 / Df is greater than 0.13, although the allowable torque continues to increase, the overall weight of the machine increases rapidly, failing to meet the usage requirements. Therefore, by balancing the overall weight of the harmonic reducer 1000 and the allowable torque requirements, the ratio of Db1 / Df is set within the range of 0.07 to 0.13. The size of the first rolling element 431 is reasonably designed, and the pitch circle distance of the structure formed by the multiple first rolling elements 431 is also reasonably designed. While ensuring the compactness of the overall structure, the requirements for maximum overturning moment and overall weight are met, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing its vibration.

[0131] Referring again to Figure 1, in this embodiment of the application, the inner diameter of the flexible wheel 200 is Df. The diameter of the circle containing the centers of the plurality of first rolling elements 431 perpendicular to the axial direction is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df. This formula is equivalent to 1.3≤Db2 / Df≤1.7, for example, the value of Db2 / Df can be 1.3, 1.4, 1.5, 1.6, 1.7, etc. Figure 17 is a graph showing the relationship between the ratio of Db2 and Df in a harmonic reducer 1000 according to an embodiment of the application, the allowable torque of the support bearing 400, and the overall weight. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Referring to Figure 17, when Db2 / Df is less than 1.3, the overall weight of the harmonic reducer 1000 is small, but the allowable torque decreases rapidly, failing to meet the usage requirements. When Db2 / Df is greater than 1.7, although the allowable torque continues to increase, the overall weight of the machine increases rapidly, which cannot meet the usage requirements. Therefore, by balancing the overall weight of the harmonic reducer 1000 and the allowable torque requirements, the value of Db2 / Df is set between 1.3 and 1.7, which can simultaneously meet the requirements of the maximum overturning moment and the overall weight requirements.

[0132] One embodiment of this application describes an industrial robot, including a motor and the harmonic reducer 1000 described in the above embodiment. It is understood that the motor can be a servo motor, and the servo motor drives the harmonic reducer 1000 for speed reduction control of the industrial robot's joints. The industrial robot can be a handling robot, welding robot, assembly robot, processing robot, painting robot, cleanroom robot, collaborative robot, etc.

[0133] The industrial robot of this application adopts the harmonic reducer 1000 of the above embodiment. By setting the wave generator 300 inside the flexible wheel 200, and making the outer tooth 210 of the flexible wheel 200 partially mesh with the inner tooth 110 of the rigid wheel 100, the wave generator 300 can drive the flexible wheel 200 and the rigid wheel 100 to rotate relative to each other when it rotates. A first groove 430 and a second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 of the support bearing 400. The first groove 430 is used to install the first rolling element 431, and the second groove 440 is used to install the second rolling element 441. The first groove 430 and the second groove 440 are spaced apart along the axial direction of the wave generator 300. By setting two sets of rolling elements, the load-bearing capacity of the harmonic reducer 1000 can be effectively improved, and the assembly efficiency between the bearing device, the rigid wheel 100, and the flexible wheel 200 can be improved while maintaining the compactness of the overall structure. Meanwhile, by setting the ratio of the tooth root wall thickness Tf of the flexible wheel 200 to the inner diameter Df of the flexible wheel 200 to between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the influence of the reduction ratio R is eliminated by using the natural logarithmic function Ln(R). This is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R and reducing the stress on the flexible wheel 200 during deformation.

[0134] Referring to Figures 18 and 19, a harmonic reducer 1000 according to an embodiment of this application includes a flexible wheel 200, a rigid wheel 100, and a wave generator 300. The flexible wheel 200 is coaxially mounted inside the rigid wheel 100, and the wave generator 300 is coaxially mounted in the inner hole of the flexible wheel 200. The flexible wheel 200 includes a cylindrical portion 220, a diaphragm portion 230, and a flange portion 240. The cylindrical portion 220 is located at the end of the flexible wheel 200 near the rigid wheel 100. The diaphragm portion 230 is connected to the end of the cylindrical portion 220 away from the rigid wheel 100 and extends radially towards the cylindrical portion 220. The flange portion 240 is connected to the outer periphery of the diaphragm portion 230. The cylindrical portion 220 of the flexible wheel 200 is provided with a flexible external tooth portion 210. The external tooth portion 210 is a structure that bulges radially outward from the cylindrical portion 220. The external tooth portion 210 is not formed in the inner hole of the flexible wheel 200, but is formed on the outer wall of the cylindrical portion 220. The rigid wheel 100 is provided with an internal toothed portion 110, and an external toothed portion 210 engages with the internal toothed portion 110, forming a meshing gap between the external toothed portion 210 and the internal toothed portion 110.

[0135] In the embodiments of this application, the wave generator 300 is interference-fitted into the inner bore of the flexible wheel 200. The wave generator 300 is configured to partially mesh with the outer tooth portion 210 and the inner tooth portion 110 when rotating. Partial meshing means that the outer tooth portion 210 of the flexible wheel 200 deforms in the circumferential direction, and the deformed part of the outer tooth portion 210 partially meshes with the corresponding position of the inner tooth portion 110. That is, the meshing position of the inner tooth portion 110 and the outer tooth portion 210 moves cyclically in the circumferential direction. When the wave generator 300 is inserted into the inner bore of the flexible wheel 200, it forces the flexible wheel 200 to undergo elastic deformation and become elliptical. During the operation of the harmonic reducer 1000, the wave generator 300 rotates at high speed, causing the flexible wheel 200 to undergo repeated deformation. This causes the outer tooth 210 of the flexible wheel 200 to mesh with the inner tooth 110 of the rigid wheel 100. The meshing position of the outer tooth 210 and the inner tooth 110 moves circumferentially along the rotation axis of the wave generator 300, thereby achieving relative deceleration between the flexible wheel 200 and the rigid wheel 100. The wave generator 300 includes a flexible bearing 320 and a cam 310. The flexible bearing 320 is sleeved on the outside of the cam 310, and the cam 310 has a mounting position for connecting a motor or other drive device.

[0136] Referring to FIG18, a harmonic reducer 1000 according to an embodiment of the present application further includes a support bearing 400, which is configured to enable the rigid wheel 100 and the flexible wheel 200 to rotate relative to each other. The support bearing 400 includes a first rolling element 431, a second rolling element 441, an outer bearing ring 410, and an inner bearing ring 420 disposed within the outer bearing ring 410. An annular first groove 430 and an annular second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 along the axial direction of the wave generator 300. The first groove 430 is located on the side away from the rigid wheel 100, and the second groove 440 is located on the side closer to the rigid wheel 100 and is spaced apart from the first groove 430. That is, the first groove 430 is located on the left side of the harmonic reducer 1000, and the second groove 440 is located on the right side of the harmonic reducer 1000. Multiple first rolling elements 431 are provided and installed in the first groove 430; multiple second rolling elements 441 are provided and installed in the second groove 440. The inner bearing ring 420 is fixedly connected to the rigid wheel 100, and the outer bearing ring 410 is fixedly connected to the flange 240 of the flexible wheel 200. The fixed connection can be achieved through fasteners (such as screws, bolts, pins, etc.), or by snap-fitting, adhesive bonding, or other methods. Therefore, the cooperation of the first rolling elements 431, the second rolling elements 441, the inner bearing ring 420, and the outer bearing ring 410 facilitates the relative rotation of the flexible wheel 200 and the rigid wheel 100.

[0137] By employing two sets of rolling elements, consisting of multiple first rolling elements 431 and multiple second rolling elements 441, the load-bearing capacity of the bearing assembly can be improved compared to the single-row crossed roller bearings in related technologies. Furthermore, the structure of the inner bearing ring 420 and the outer bearing ring 410 facilitates the assembly of the harmonic reducer 1000 and makes it easier to adapt to different loads. It is understood that the first rolling element 431 can be a sphere, or a cylindrical or conical shape; the second rolling element 441 can also be a sphere, or a cylindrical or conical shape, etc., and is not specifically limited here. In addition, in this embodiment, the first rolling elements 431 and the second rolling elements 441 can be made of metal materials such as steel.

[0138] It should be noted that the inner hole of the flexible wheel 200 is circular when it is not installed with the wave generator 300. After the flexible wheel 200 and the wave generator 300 are assembled, the outer tooth 210 of the flexible wheel 200 becomes elliptical. Due to the structural relationship of the flexible wheel 200, the deformation of different sections of the outer tooth 210 along the axial direction is different, and the deformation is greater closer to the opening of the cylinder 220. Generally, the meshing state of the middle tooth section of the outer tooth 210 along the axial direction is optimal. The tooth section near the flange 240 is prone to interference with the tooth tip of the inner tooth 110 of the rigid wheel 100 or the clearance is too small, resulting in abnormal friction and wear and noise. The tooth section away from the flange 240 is prone to interference with the tooth root or middle part of the inner tooth 110 of the rigid wheel 100, which also results in abnormal friction and wear and noise. Since the rigid wheel and the inner bearing ring 420 are fixedly connected, and the fixed connection is usually made by screws or bolts, it is necessary to set mounting holes 427 on the inner bearing ring 420. This may cause deformation of the raceway on the inner bearing ring 420, which increases the machining difficulty of the inner bearing ring 420.

[0139] To address the issues of easy interference between the external gear portion 210 and the internal gear portion 110, and the high machining difficulty of the inner bearing ring 420, as shown in Figures 3 and 4, in the embodiments of this application, the rigid wheel 100 includes a first mounting portion 120 and an internal gear portion 110 connected to the inner side of the first mounting portion 120. The first mounting portion 120 and the inner bearing ring 420 are connected by fasteners, for example, by providing mounting holes 427 in the bearing ring 420, and by using screws, bolts, or other structures to pass through the mounting holes 427 and connect and fix the first mounting portion 120 and the inner bearing ring 420. The first mounting portion 120 is connected to the end of the internal gear portion 110 that is away from the inner bearing ring 420, and the internal gear portion 110 includes a thin-walled section 111 protruding from the first mounting portion 120.

[0140] Understandably, with the above-described scheme, since the rigid wheel 100 includes a connected first mounting portion 120 and an internal gear portion 110, and the first mounting portion 120 is located at the end of the internal gear portion 110 opposite to the inner bearing ring 420, the inner bearing ring 420 can extend to the outer side wall of the internal gear portion 110, resulting in a relatively long overall length of the inner bearing ring 420. Providing mounting holes 427 on the inner bearing ring 420 has a smaller impact on the raceway, thus reducing the machining difficulty of the support bearing 400. Simultaneously, since the internal gear portion 110 protrudes from the first mounting portion 120, it has a thin-walled design, allowing for elastic deformation to a certain extent. Therefore, without reducing the meshing depth between the internal gear portion 110 and the external gear portion 210, the elastic deformation of the internal gear portion 110 reduces interference with the external gear portion 210, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing vibration and noise.

[0141] Referring to Figures 20 and 21, in the embodiments of this application, along the axial direction of the wave generator 300, the maximum width of the thin-walled section 111 is Lc1, and the maximum width of the internal gear section 110 is Lc, satisfying: 0.6*Lc≤Lc1≤0.9*Lc. This formula is equivalent to 0.6≤Lc1 / Lc≤0.9, for example, the value of Lc1 / Lc can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, etc. Referring to Figure 11, the horizontal axis in Figure 11 represents the value of Lc1 / Lc, the vertical axis on the left represents the torsional stiffness of the harmonic reducer 1000, and the vertical axis on the right represents the vibration acceleration of the harmonic reducer 1000. Torsional stiffness refers to the slope of the line segment taken on the mechanical hysteresis loop, expressed as the torque change corresponding to a unit torsional angle. Torsional stiffness describes the ratio between the relative torsional angle generated by elastic deformation and the load. The greater the torsional stiffness, the smaller the torsional angle of the output shaft when subjected to external forces, resulting in higher positioning accuracy. Vibration acceleration refers to the acceleration generated by vibration phenomena caused by various internal and external factors during the operation of the reducer. Vibration acceleration reflects the stability and smoothness of the reducer during dynamic operation. Lower vibration acceleration means that the harmonic reducer 1000 is more stable and smoother during operation, which helps to reduce wear and energy loss of the harmonic reducer 1000 and improve the overall performance and lifespan of the reducer. At the same time, compared with the rigid wheel in related technologies, the width of the internal tooth portion 110 in this embodiment is increased, which can increase the contact area with the external tooth portion 210, reduce the meshing surface pressure of the tooth surface, and improve the load-bearing capacity of the harmonic reducer 1000.

[0142] As shown in Figure 23, as the value of Lc1 / Lc gradually increases, the torsional stiffness decreases gradually in the range of 0.4 to 0.8, and the rate of decrease increases in the range of 0.8 to 1; the vibration acceleration decreases more rapidly in the range of 0.4 to 0.75, and the rate of decrease is relatively slow in the range of 0.75 to 1. When the value of Lc1 / Lc is less than 0.6, although the torsional stiffness is large, the vibration acceleration is also large, and the operational stability of the harmonic reducer 1000 deteriorates. When the value of Lc1 / Lc is greater than 0.9, the vibration acceleration is small, but the torsional stiffness is also small. Therefore, by reasonably designing the value of Lc1 / Lc to be within the range of 0.6 to 0.9, it is possible to reduce the vibration acceleration while maintaining the torsional stiffness at an appropriate level, thereby improving the operational stability of the harmonic reducer 1000.

[0143] Referring to Figures 18 and 20, in the embodiments of this application, the maximum wall thickness of the thin-walled section 111 is Tc. The maximum wall thickness Tc of the thin-walled section 111 refers to the thickness between the outer circumference of the thin-walled section 111 and the tip circle of the internal tooth portion 110 along the radial direction of the rigid wheel 100. The inner diameter of the flexible wheel 200 is Df, satisfying: 0.015*Df≤Tc≤0.05*Df. This formula is equivalent to 0.015≤Tc / Df≤0.05, for example, the value of Tc / Df can be 0.015, 0.02, 0.025, 0.03, 0.04, 0.05, etc. The inner diameter Df of the flexible wheel 200 is usually a constant value. The larger the maximum wall thickness Tc of the thin-walled section 111, the more difficult it is to produce elastic deformation. Referring to Figure 12, the horizontal axis represents the value of Tc / Df, the left vertical axis represents the stress of the rigid wheel 100, and the right vertical axis represents the vibration acceleration of the harmonic reducer 1000. When the value of Tc / Df is less than 0.015, although the vibration acceleration is small, the stress of the rigid wheel 100 is too small, resulting in low overall strength of the rigid wheel 100. When the value of Tc / Df is greater than 0.05, the vibration acceleration and the stress of the rigid wheel 100 are too large, reducing the operational stability of the harmonic reducer 1000. Furthermore, the rigid wheel 100 is less likely to undergo elastic deformation to reduce interference with the external gear 210, leading to a decrease in the load-bearing capacity of the harmonic reducer 1000. Therefore, by reasonably designing the value of Tc / Df to be within the range of 0.015 to 0.05, the vibration acceleration can be reduced while ensuring that the stress of the rigid wheel 100 is within a suitable range. This ensures the strength of the rigid wheel 100 while giving it a certain ability to elastically deform, thereby reducing the interference between the rigid wheel 100 and the flexible wheel 200 and improving the service life of the flexible wheel 200.

[0144] Referring to Figures 20 and 21, in the embodiments of this application, the connection between the thin-walled segment 111 and the first mounting portion 120 is constructed as a curve 130, which is composed of at least two arc segments. It is understood that the smooth transition of the connection between the thin-walled segment 111 and the first mounting portion 120 via the curve 130 effectively reduces stress concentration at the connection. When the curve 130 is composed of at least two arc segments, i.e., the radii or angles of the two arc segments are different, the connection between the thin-walled segment 111 and the first mounting portion 120 can transition more smoothly, further reducing stress concentration and mitigating adverse effects such as cracking at the connection.

[0145] Referring again to Figures 20 and 21, in this embodiment, curve 130 connects to the outer side of the thin-walled segment 111 at point a, and curve 130 connects to the first mounting portion 120 at point e. Along the axial direction of the wave generator 300, the distance from point a to point e is Lwa, satisfying: 0.1*Lc1≤Lwa≤0.3*Lc1. This formula is equivalent to 0.1≤Lwa / Lc1≤0.3, where Lwa / Lc1 can be 0.1, 0.15, 0.2, 0.25, 0.3, etc. The above formula reflects the proportion of curve 130 along the axial direction of the thin-walled segment 111. When the value of Lwa / Lc1 is less than 0.1, meaning the length of curve 130 along the axial direction is short, it is difficult to reduce the stress at the connection between the first mounting portion 120 and the thin-walled segment 111. When the value of Lwa / Lc1 is greater than 0.3, the axial length of curve 130 is too long, which is not conducive to the abutment fit between the inner bearing ring 420 and the outer wall of the thin-walled section 111, affecting the fit accuracy. Therefore, by reasonably designing the value of Lwa / Lc1 to be within the range of 0.1 to 0.3, it is possible to ensure the fit accuracy between the inner bearing ring 420 and the thin-walled section 111 while reducing the stress at the connection between the thin-walled section 111 and the first mounting part 120, thereby reducing stress concentration and improving the load-bearing capacity of the rigid wheel 100.

[0146] Referring to Figure 21, in this embodiment of the application, curve 130 has points b, c, and d. The distance from point a to point b is Lwb, the distance from point b to point c is Lwc, and the distance from point c to point d is Lwd. Lwb = Lwc = Lwd = Lwa / 4, meaning curve 130 is divided into four equal parts axially. Along the radial direction of the rigid wheel 100, the distances from point b, c, d, and e to point a are Lrb, Lrc, Lrd, and Lre, respectively, where Lrb < Lrc < Lrd < Lre, satisfying: 0.1*Tc ≤ Lre ≤ 0.4*Tc, Lrb + Lrc + Lrd ≤ Lre / 2. Here, 0.1*Tc ≤ Lre ≤ 0.4*Tc is equivalent to 0.1 ≤ Lre / Tc ≤ 0.4. For example, the value of Lre / Tc can be 0.1, 0.2, 0.3, 0.4, etc. Understandably, when Lre / Tc is less than 0.1 and Lrb+Lrc+Lrd>Lre / 2, meaning the height of curve 130 in the radial direction of the rigid wheel 100 is low, it is difficult to achieve a smooth transition at the connection between the thin-walled section 111 and the first mounting part 120, and the effect of reducing stress concentration is not significant. When Lre / Tc is greater than 0.4, meaning the height of curve 130 in the radial direction of the rigid wheel 100 is high, it is not conducive to the mating fit between the inner bearing ring 420 and the thin-walled section 111. Therefore, by reasonably designing the value of Lre / Tc to be within the range of 0.1 to 0.4, and Lrb+Lrc+Lrd≤Lre / 2, the stress concentration at the connection between the thin-walled section 111 and the first mounting part 120 can be effectively reduced, while also facilitating the mating fit between the inner bearing ring 420 and the thin-walled section 111, thus improving installation efficiency.

[0147] Table 2: Comparison of maximum stress at the connection between the thin-walled section 111 and the first mounting part 120 under three different schemes

[0148] In Table 2 above, Scheme 4 is a scheme in which the first mounting part 120 and the thin-walled section 111 are directly connected without the curve 130; Scheme 5 is a scheme in which the first mounting part 120 and the thin-walled section 111 are connected by a straight section; Scheme 6 is the scheme of this embodiment, which is the scheme in which the curve 130 is used to connect the first mounting part 120 and the thin-walled section 111. As can be seen from the table above, the scheme of this embodiment can effectively reduce the maximum stress at the connection between the thin-walled section 111 and the first mounting part 120, effectively avoid the phenomenon of stress concentration, and improve the load-bearing capacity of the rigid wheel 100.

[0149] Referring to FIG22, in the embodiment of this application, the portion of the internal gear 110 protruding axially from the first mounting portion 120 abuts against the inner side of the inner bearing ring 420. Therefore, the inner bearing ring 420 supports the internal gear 110, preventing excessive force on the internal gear 110 and thus avoiding large-angle bending deformation, thereby improving the reliability of the rigid wheel 100. One end of the inner bearing ring 420 is provided with a protrusion 421 along the axial direction. The protrusion 421 protrudes towards the first mounting portion 120, and the inner side of the protrusion 421 abuts against the outer side of the first mounting portion 120. It can be understood that the protrusion 421 can serve a positioning function for the installation of the rigid wheel 100. Simultaneously, the protrusion 421 also facilitates the installation of the oil seal 500 between the inner bearing ring 420 and the outer bearing ring 410. The oil seal 500 is annular and concentrically positioned with the outer bearing ring 410. The outer side of the oil seal 500 is interference-fitted with the inner hole of the outer bearing ring 410, and the inner hole of the oil seal 500 is sealed with the outer wall of the protrusion 421 to improve the sealing effect. When the inner bearing ring 420 and the oil seal 500 rotate relative to each other, they can also form a radial contact seal, thereby effectively preventing the lubricating material in the first groove 430 and the second groove 440 from overflowing into the rigid wheel 100.

[0150] Referring to FIG5, in an embodiment of this application, the external tooth portion 210 includes a plurality of protruding teeth arranged circumferentially along the flexible wheel 200. Each protruding tooth includes a first tooth segment 211, a second tooth segment 212, and a third tooth segment 213 extending axially. From the external tooth portion 210 to the flange portion 240, i.e., from right to left in FIG7, the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 are connected sequentially. The tip circle diameter of the first tooth segment 211 gradually decreases in the direction away from the flange portion 240, and the tip circle diameter of the second tooth segment 212 gradually decreases in the direction towards the flange portion 240. That is, the first tooth segment 211 and the second tooth segment 212 adopt a tooth-direction modification scheme, and the tooth height of the first tooth segment 211 and the second tooth segment 212 gradually decreases in the direction away from the third tooth segment 213. The tooth height refers to the height in the radial direction. For example, the tip of the first tooth segment 211 and the second tooth segment 212 can be inclined in a straight line, or be an outwardly convex arc, an inwardly concave arc, etc. By setting the tooth height of the first tooth segment 211 and the second tooth segment 212 to gradually decrease, the interference between the tooth tip of the first tooth segment 211 and the tooth tip of the second tooth segment 212 and the internal tooth portion 110 can be effectively reduced, thereby improving the service life of the flexible gear 200.

[0151] Referring again to Figure 5, in the embodiment of this application, the diameter of the tip circle of the third tooth segment 213 is constant, that is, the tooth height of the third tooth segment 213 remains unchanged. Because the flexible wheel 200, under the action of the wave generator 300, has an elliptical shape after the cylindrical portion 220 becomes elliptical, the motion trajectory of the outer tooth portion 210 is different at different cross-sections. The state is optimal in the middle part of the outer tooth portion 210, that is, the third tooth segment 213, where interference is less likely to occur. However, interference with the inner tooth portion 110 is more likely to occur at the two ends of the outer tooth portion 210 along the axial direction. Therefore, by designing the tooth height of the first tooth segment 211 and the tooth height of the second tooth segment 212 to gradually decrease in the direction away from the third tooth segment 213, the interference between the tip of the first tooth segment 211 and the tip of the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced.

[0152] Referring to Figures 19 and 6, in the embodiments of this application, the effective width of the flexible wheel 200 along the direction parallel to the rotation axis of the wave generator 300 is Lf. The effective width of the flexible wheel 200 refers to the minimum distance between the end face of the cylindrical portion 220 away from the flange portion 240 and the flange portion 240. The tooth width of the external tooth portion 210 is Lf1, satisfying: 0.4*Lf≤Lf1≤0.6*Lf. For example, the value of Lf1 can be 0.4*Lf, 0.45*Lf, 0.5*Lf, 0.55*Lf, or 0.6*Lf. The width of the first tooth segment 211 is Lf2, satisfying: 0.2*Lf1≤Lf2≤0.35*Lf1. For example, the value of Lf2 can be 0.2*Lf1, 0.23*Lf1, 0.24*Lf1, 0.25*Lf1, 0.3*Lf1, or 0.35*Lf1. The width of the third tooth segment 213 is Lf3, satisfying: 0.35*Lf1≤Lf3≤0.45*Lf1. For example, the value of Lf3 can be 0.35*Lf1, 0.38*Lf1, 0.39*Lf1, 0.40*Lf1, 0.42*Lf1, or 0.45*Lf1. The width of the second tooth segment 212 is Lf4, which satisfies: 0.25*Lf1≤Lf4≤0.4*Lf1. For example, the value of Lf4 can be 0.25*Lf1, 0.28*Lf1, 0.3*Lf1, 0.35*Lf1, 0.38*Lf1, or 0.4*Lf1.

[0153] Understandably, the widths of the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 affect the meshing effect with the internal tooth portion 110. When Lf1 is less than 0.4*Lf, the tooth width of the external tooth portion 210 is shorter, reducing the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, thus worsening the stability during meshing. When Lf1 is greater than 0.6*Lf, the tooth width of the external tooth portion 210 is longer, increasing the volume of the harmonic accelerator and hindering compact design. When Lf2 is less than 0.2*Lf1, meaning the width of the first tooth segment 211 is smaller, interference with the internal tooth portion 110 is more likely. When Lf2 is greater than 0.4*Lf1, meaning the width of the first tooth segment 211 is larger, the width of the third tooth segment 213 needs to be shortened accordingly while keeping the width of the external tooth portion 210 constant, resulting in a reduction in the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, further worsening the stability during meshing. When Lf3 is less than 0.35*Lf1, meaning the width of the third tooth segment 213 is small, the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110 will decrease, resulting in poorer stability during meshing. When Lf3 is greater than 0.45*Lf1, with the width of the external tooth portion 210 remaining constant, the widths of the first tooth segment 211 and the second tooth segment 212 need to be reduced accordingly, which can easily lead to interference with the internal tooth portion 110 at the first tooth segment 211 and the second tooth segment 212. When Lf4 is less than 0.25*Lf1, meaning the width of the second tooth segment 212 is small, it is easy to interfere with the internal tooth portion 110. When Lf4 is greater than 0.45*Lf1, meaning the width of the second tooth segment 212 is large, with the width of the external tooth portion 210 remaining constant, the width of the third tooth segment 213 needs to be shortened accordingly, resulting in a decrease in the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110, and worsening stability during meshing.

[0154] Therefore, by rationally designing the ratio of the tooth width of the external tooth section 210 to the effective width of the flexible gear 200 to be between 0.4 and 0.6, the ratio of the width of the first tooth segment 211 to the width of the external tooth section 210 to be between 0.2 and 0.35, the ratio of the width of the third tooth segment 213 to the width of the external tooth section 210 to be between 0.35 and 0.45, and the ratio of the width of the second tooth segment 212 to the width of the external tooth section 210 to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the external tooth section 210 and the internal tooth section 110, while also reducing the interference between the external tooth section 210 and the internal tooth section 110, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear 200.

[0155] Referring to FIG6, in the embodiment of this application, the inclination angle of the first tooth segment 211 is α1, and the inclination angle of the second tooth segment is β1. It should be noted that the inclination angle α1 of the first tooth segment 211 refers to the fact that the tooth tip of the first tooth segment 211 is constructed as a first inclined surface 2111, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle α1 between the first inclined surface 2111 and the rotation axis. The inclination angle β1 of the second tooth segment refers to the fact that the tooth tip of the second tooth segment 212 is constructed as a second inclined surface 2112, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle β1 between the second inclined surface 2112 and the rotation axis.

[0156] The inclination angle α1 of the first tooth segment 211 and the inclination angle β1 of the second tooth segment satisfy the following conditions: 0.3°≤α1≤1°, 0.3°≤β1≤1°, and β1<α1. For example, the value of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°; and the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α1 is less than 0.3°, that is, the inclination angle of the first inclined surface 2111 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α1 is greater than 1°, it is easy to reduce the effective area when the first tooth segment 211 and the internal tooth portion 110 mesh, thus leading to a decrease in meshing stability. When β1 is less than 0.3°, that is, the inclination angle of the second inclined surface 2112 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β1 is greater than 1°, it can easily lead to a reduction in the effective area when the second tooth segment 212 and the internal tooth portion 110 mesh, thereby resulting in poor meshing stability.

[0157] Understandably, because the second tooth segment 212 is closer to the thin-walled segment 111, the thin-walled segment 111 can cause the second tooth segment 212 to undergo a certain degree of elastic deformation, thereby reducing the interference between the outer tooth portion 210 and the second tooth segment 212 of the flexible gear 200. However, the first tooth segment 211 is closer to the first mounting portion 120, and the first tooth segment 211 is more likely to interfere with the outer tooth portion 210. Therefore, by setting β1 < α1, the interference between the inner tooth portion 110 and the outer tooth portion 210 can be effectively reduced, thereby improving the stability during power transmission.

[0158] Referring again to Figure 6, in this embodiment of the application, to further reduce interference between the external tooth portion 210 and the internal tooth portion 110, a third inclined surface 2121 is provided between two adjacent first tooth segments 211. The third inclined surface 2121 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. A fourth inclined surface 2122 is provided between two adjacent second tooth segments 212. The fourth inclined surface 2122 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. The inclination angle of the third inclined surface 2121 can be the same as or different from that of the first inclined surface 2111, and the inclination angle of the fourth inclined surface 2122 can be the same as or different from that of the second inclined surface 2112. This effectively reduces or avoids interference between the tooth tip of the internal tooth portion 110 and the tooth root of the external tooth portion 210, thereby reducing tooth surface friction and wear and extending the life of the flexible gear 200.

[0159] Referring again to Figure 6, in this embodiment of the application, the inclination angle of the third inclined surface 2121 is α2, satisfying: 0.3°≤α2≤1.0°. For example, the value of α2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1.0°. When α2 is less than 0.3°, that is, the inclination angle of the third inclined surface 2121 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α2 is greater than 1°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent protrusions. Therefore, by reasonably designing the sizes of α1 and α2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0160] Referring again to Figure 6, in this embodiment of the application, the inclination angle of the fourth inclined surface 2122 is β2, satisfying: 0°≤β2≤0.4°. For example, the value of β2 can be 0.1°, 0.2°, 0.3°, or 0.4°. When β2 is greater than 0.4°, it can easily lead to a decrease in the strength of the external tooth portion 210, and tearing can easily occur between adjacent protruding teeth. Therefore, by rationally designing the sizes of β1 and β2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0161] Table 3: Comparison of tooth surface contact area under different schemes

[0162] For example, referring to Table 3 above, Scheme 7 is a scheme in the related art, where Lc = 0.42 * Lf, Lf1 = 0.36 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 8 has Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 9 has Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the first tooth segment 211 and the second tooth segment 212 of the external tooth portion 210 adopt a modification scheme. As can be seen from Table 3 above, designing Lc = 0.55 * Lf and Lf1 = 0.5 * Lf can increase the tooth surface contact area by 19.2%, and further adding a modification scheme on this basis increases the improvement by 38.5% compared to Scheme 7. The larger the contact area of ​​the tooth surface, the smaller the contact stress, and the greater the load-bearing capacity of the harmonic reducer 1000.

[0163] Flexible gears 200 of the same specification have the same inner diameter and basically the same external dimensions. When the reduction ratio of the harmonic reducer 1000 is different, the number of teeth and the module of the flexible gear 200 are usually different, resulting in different stresses when the flexible gear 200 deforms. In order to reduce the stress on the flexible gear 200 during deformation and simplify the design of flexible gears 200 of the same specification but different reduction ratios, as shown in Figures 1 and 5, in the embodiments of this application, the tooth root wall thickness of the flexible gear 200 is Tf. The tooth root wall thickness Tf refers to the distance between the tooth root of the outer tooth portion 210 and the inner hole wall of the flexible gear 200 along the radial direction of the flexible gear 200. The inner diameter of the flexible gear 200 is Df, and the reduction ratio of the harmonic reducer 1000 is R, satisfying: 0.0043ln(R)-0.0061≤Tf / Df≤0.005ln(R)-0.0036. The reduction ratio R can be obtained from the parameters marked on the nameplate of the harmonic reducer 1000. Referring to Figure 25, the horizontal axis of the graph in Figure 25 represents the value of Tf / Df, and the vertical axis represents the tooth root stress of the flexible gear 200. It can be seen from the figure that as the value of Tf / Df gradually increases, the tooth root stress on the flexible gear 200 first decreases and then increases, with a minimum value for the tooth root stress. Therefore, for flexure wheels 200 of the same specification but with different reduction ratios, the influence of the reduction ratio R can be eliminated by using the natural logarithmic function Ln(R). This only requires ensuring that the values ​​of Tf / Df are limited to the ranges of 0.0043ln(R)-0.0061 and 0.005ln(R)-0.0036, which effectively reduces the stress on the flexure wheel 200 and simplifies its design, thereby improving production efficiency. Furthermore, compared to flexure wheels in related technologies, the tooth root wall thickness Tf of the flexure wheel 200 in this embodiment is increased, effectively improving the load-bearing capacity and torsional stiffness of the harmonic reducer 1000.

[0164] Referring to FIG19, in the embodiment of this application, along the axial direction of the wave generator 300, the effective width of the flexible wheel 200 is Lf, which refers to the minimum distance between the end face of the cylindrical portion 220 away from the flange portion 240 and the flange portion 240. The width of the internal gear portion 110 is Lc, which refers to the maximum length of the internal gear portion 110 along the axial direction, for example, the distance between the two farthest end faces of the rigid wheel 100 along the axial direction. The relationship between Lf and Lc satisfies: 0.45*Lf≤Lc≤0.65*Lf. The value of Lc can be 0.45*Lf, 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, or 0.65*Lf. When Lc is less than 0.45*Lf, meaning the maximum length of the internal gear 110 is short, the contact area between the internal gear 110 and the external gear 210 decreases, increasing contact stress and reducing the load-bearing capacity of the harmonic reducer 1000. When Lc is greater than 0.65*Lf, meaning the maximum length of the internal gear 110 is large, it occupies too much space and has too large a strength margin, which is not conducive to the miniaturization design of the harmonic reducer 1000. Therefore, rationally designing the maximum length Lc and Lf of the internal gear 110 can effectively increase the contact area between the internal gear 110 and the external gear 210, reduce contact stress, improve the load-bearing capacity of the harmonic reducer 1000, and also facilitate the miniaturization design of the harmonic reducer 1000.

[0165] Referring to Figures 22, 7, and 9, in the embodiments of this application, the outer bearing ring 410 includes a second mounting portion 411 and a protrusion 412 connected to the inner side of the second mounting portion 411. The protrusion 412 has a first outer raceway 413 and a second outer raceway 414 respectively, which are opposite to each other, at both ends along the axial direction. The protrusion 412 enhances the structural strength of the first outer raceway 413 and the second outer raceway 414, effectively reducing their deformation, and also limits the movement of the first rolling element 431 and the second rolling element 441, preventing them from contacting each other. The outer side of the inner bearing ring 420 has a groove 422 opposite to the protrusion 412. The groove 422 has a first inner raceway 423 and a second inner raceway 424 respectively at both ends along the axial direction. The first inner raceway 423 and the first outer raceway 413 are arranged opposite each other to form a first groove 430, and the second inner raceway 424 and the second outer raceway 414 are arranged opposite each other to form a second groove 440. This arrangement facilitates the installation of the first rolling element 431 and the second rolling element 441, improves assembly efficiency, and allows the first rolling element 431 and the second rolling element 441 to rotate smoothly, thus improving the stability of the support bearing 400 during operation.

[0166] Referring to FIG22, in the embodiment of this application, there is a gap between the bottom wall of the protrusion 412 and the groove 422, and the first groove 430 and the second groove 440 are connected through the gap. It can be understood that by setting the first groove 430 and the second groove 440 to be connected through the gap, it is beneficial for lubricating oil to flow in the first groove 430 and the second groove 440, thereby lubricating the first rolling element 431 and the second rolling element 441, improving the smoothness and service life of the first rolling element 431 and the second rolling element 441 during rolling.

[0167] Referring again to Figure 22, in this embodiment of the application, the inner bearing ring 420 includes a first ring body 425 and a second ring body 426 connected together. The first ring body 425 and the second ring body 426 are arranged from left to right and are connected by fasteners. A step is provided on the side of the first ring body 425 facing the second ring body 426, and the second ring body 426 is positioned and connected to the step. The step serves a positioning function, thereby facilitating the connection between the first ring body 425 and the second ring body 426. A first inner raceway 423 is located outside the first ring body 425 and close to the second ring body 426, and a second inner raceway 424 is located outside the second ring body 426 and away from the first ring body 425. The second ring body 426 is connected to the rigid wheel 100. By designing the inner bearing ring 420 with the first ring body 425 and the second ring body 426 connected, the installation of the first rolling element 431 and the second rolling element 441 is facilitated, reducing assembly difficulty.

[0168] Referring again to FIG22, in the embodiment of this application, the outer side of the thin-walled segment 111 abuts against the inner side of the second ring 426. Along the axial direction of the wave generator 300, the end of the second ring 426 away from the first ring 425 abuts against the end of the first mounting portion 120 facing the thin-walled segment 111, which can play a positioning role for the second ring 426, facilitating the assembly of the second ring 426 and improving assembly efficiency.

[0169] One embodiment of this application describes an industrial robot, including a motor and the harmonic reducer 1000 described in the above embodiment. It is understood that the motor can be a servo motor, and the servo motor drives the harmonic reducer 1000 for speed reduction control of the industrial robot's joints. The industrial robot can be a handling robot, welding robot, assembly robot, processing robot, painting robot, cleanroom robot, collaborative robot, etc.

[0170] The industrial robot of this application adopts the harmonic reducer 1000 of the above embodiment. By setting the wave generator 300 inside the flexible wheel 200, and making the outer tooth 210 of the flexible wheel 200 partially mesh with the inner tooth 110 of the rigid wheel 100, the wave generator 300 can drive the flexible wheel 200 and the rigid wheel 100 to rotate relative to each other when it rotates. A first groove 430 and a second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 of the support bearing 400. The first groove 430 is used to install the first rolling element 431, and the second groove 440 is used to install the second rolling element 441. The first groove 430 and the second groove 440 are spaced apart along the axial direction of the wave generator 300. By setting two sets of rolling elements, the load-bearing capacity of the harmonic reducer 1000 can be effectively improved, and the assembly efficiency between the bearing device, the rigid wheel 100, and the flexible wheel 200 can be improved while maintaining the compactness of the overall structure. Since the rigid wheel 100 includes a first mounting portion 120 and an internal gear portion 110 connected to each other, and the first mounting portion 120 is located at the end of the internal gear portion 110 opposite to the inner bearing ring 420, the inner bearing ring 420 can extend to the outer side wall of the internal gear portion 110, resulting in a relatively long overall length. Providing mounting holes on the inner bearing ring 420 has a smaller impact on the raceway, reducing the machining difficulty of the support bearing 400. Simultaneously, since the internal gear portion 110 protrudes from the first mounting portion 120, it has a thin-walled design, allowing for elastic deformation to a certain extent. Therefore, without reducing the meshing depth between the internal gear portion 110 and the external gear portion 210, the elastic deformation of the internal gear portion 110 reduces interference with the external gear portion 210, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing vibration and noise.

[0171] The industrial robot of this application adopts all the technical solutions of the harmonic reducer 1000 of the above embodiments, and therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0172] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. Harmonic reducer, including: Rigid wheel, including internal gears; A flexible wheel is disposed inside the rigid wheel, and the flexible wheel includes an external toothed portion; A wave generator is disposed inside the flexible gear and is used to partially mesh the external teeth with the internal teeth; as well as A support bearing is configured to allow the rigid wheel and the flexible wheel to rotate relative to each other. The support bearing includes an outer bearing ring and an inner bearing ring disposed within the outer bearing ring. The inner bearing ring and the outer bearing ring have a first groove for mounting a first rolling element and a second groove for mounting a second rolling element. The first groove and the second groove are spaced apart along the axial direction of the wave generator. Wherein, the tooth root wall thickness of the flexure is Tf, the inner diameter of the flexure is Df, and the reduction ratio of the harmonic reducer is R, satisfying: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036.

2. The harmonic reducer according to claim 1, wherein: Along the axial direction, the effective width of the flexible wheel is Lf, and the width of the internal tooth is Lc, satisfying: 0.45*Lf≤Lc≤0.65*Lf.

3. The harmonic reducer according to claim 1 or 2, wherein: The rigid wheel also includes a first mounting portion connected to the inner bearing ring, and the internal tooth portion is connected to the inner side of the first mounting portion. Along the axial direction of the wave generator, the width of the internal tooth portion is greater than the width of the first mounting portion.

4. The harmonic reducer according to claim 3, wherein: The portion of the internal tooth protruding axially from the first mounting portion abuts against the inner side of the inner bearing ring; and The inner bearing ring has a protrusion at one end along the axial direction that protrudes toward the first mounting portion, and the inner side of the protrusion abuts against the outer side of the first mounting portion.

5. The harmonic reducer according to claim 3 or 4, wherein: The first mounting portion is connected to one end of the internal tooth portion that is axially away from the inner bearing ring.

6. The harmonic reducer according to any one of claims 1 to 5, wherein: The flexible wheel also includes a cylinder, a diaphragm, and a flange. The external toothed portion is connected to the outside of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, and the flange is connected to the end of the diaphragm away from the cylinder. The flange and the outer bearing ring are fixedly connected.

7. The harmonic reducer according to claim 6, wherein: Along the axial direction of the wave generator, the first rolling element is located between the diaphragm and the internal tooth portion. The width of the internal tooth portion is Lc, and the minimum distance between the end face of the internal tooth portion facing the first rolling element and the center of the second rolling element is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc. When L3>0, the center of the second rolling element is located between the two end faces of the external tooth portion along the axial direction, and when L3<0, the center of the second rolling element is located between the external tooth portion and the diaphragm.

8. The harmonic reducer according to claim 6 or 7, wherein: Along the axial direction, the external toothed portion includes a first tooth segment away from the flange end and a second tooth segment near the flange end. The diameter of the tip circle of the first tooth segment gradually decreases in the direction away from the flange, and the diameter of the tip circle of the second tooth segment gradually decreases in the direction toward the flange.

9. The harmonic reducer according to claim 8, wherein: The external tooth portion also includes a third tooth segment located between the first tooth segment and the second tooth segment, wherein the diameter of the tip circle of the third tooth segment is constant.

10. The harmonic reducer according to claim 9, wherein: Along the axial direction, the effective width of the flexible wheel is Lf, the width of the external tooth is Lf1, the width of the first tooth segment is Lf2, the width of the second tooth segment is Lf4, and the width of the third tooth segment is Lf3, satisfying: 0.4*Lf≤Lf1≤0.6*Lf; 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

11. The harmonic reducer according to claim 8, wherein: The inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.3°≤α1≤1.0°, 0.3°≤β1≤1.0°, and β1≥α1.

12. The harmonic reducer according to any one of claims 1 to 11, wherein: The flexible wheel further includes a cylindrical portion, a diaphragm portion, and a flange portion. The external toothed portion is connected to the outer side of one end of the cylindrical portion. The diaphragm portion is connected to the other end of the cylindrical portion and extends radially along the cylindrical portion. The flange portion is connected to the end of the diaphragm portion away from the cylindrical portion. The flange portion and the outer bearing ring are fixedly connected and satisfy at least one of the following conditions: The effective width of the flexible wheel along the axial direction is Lf, and the maximum distance between the outer bearing ring abutting the end wall of one end of the flange and the center of the first rolling element is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf; The effective width of the flexible wheel along the axial direction is Lf, and the maximum distance between the center of the first rolling element and the center of the second rolling element in the direction parallel to the axial direction is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

13. The harmonic reducer according to any one of claims 1 to 12, wherein: The outer bearing ring includes a second mounting portion and a protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring is provided with a groove opposite to the protrusion, and the two ends of the groove along the axial direction are respectively a first inner raceway and a second inner raceway; and The first inner raceway and the first outer raceway are arranged opposite each other to form the first groove, and the second inner raceway and the second outer raceway are arranged opposite each other to form the second groove.

14. The harmonic reducer according to claim 13, wherein: There is a gap between the protrusion and the bottom wall of the groove, and the first groove and the second groove are connected through the gap.

15. The harmonic reducer according to claim 13 or 14, wherein: The inner bearing ring includes a first ring body and a second ring body connected to each other. The first inner raceway is located outside the first ring body and close to the second ring body, and the second inner raceway is located outside the second ring body and away from the first ring body. The second ring body is connected to the rigid wheel.

16. The harmonic reducer according to any one of claims 13 to 15, wherein: Within a cross-section passing through the rotation axis of the wave generator, the outer contour of the first inner raceway is a first curve, the first curve including a first circular arc segment and a first modified segment, the first modified segment being a non-circular arc; and The radius of the first arc segment is Ri, and the maximum cross-sectional diameter of the first rolling element is Db1. A coordinate system is established with the center of the first arc segment as the origin. The X-axis is parallel to the rotation axis and points away from the second rolling element, and the Y-axis is perpendicular to the X-axis and points towards the rotation axis. The first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi = Ri, when θ1 > βi; Where, Ri = (0.505~0.515)*Db1, ki = 0.002~0.004, βi = 20°-30°.

17. The harmonic reducer according to any one of claims 13 to 16, wherein: Within a cross-section passing through the rotation axis of the wave generator, the outer contour of the first outer raceway is a second curve, which includes a second circular arc segment and a second modified segment, wherein the second modified segment is a non-circular arc; and The radius of the second arc segment is Ro, and the maximum cross-sectional diameter of the first rolling element is Db1. A coordinate system is established with the center of the second arc segment as the origin. The X-axis is parallel to the rotation axis and points in the direction of the second rolling element, and the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis. The second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; Among them, Ro=(0.505~0.515)*Db1, ko=0.002~0.004, βo=20°-30°.

18. The harmonic reducer according to any one of claims 1 to 17, wherein at least one of the following conditions is met: The inner diameter of the flexible wheel is Df, and the maximum cross-sectional diameter of the first rolling element is Db1, satisfying: 0.07*Df≤Db1≤0.13*Df; The inner diameter of the flexible wheel is Df, and the diameter of the circle containing the centers of the plurality of first rolling elements perpendicular to the axial direction is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df.

19. Harmonic reducer, including: The rigid wheel includes a first mounting portion and an internal tooth portion connected to the inner side of the first mounting portion; A flexible wheel is disposed inside the rigid wheel, and the flexible wheel includes an external toothed portion; A wave generator is disposed inside the flexible gear and is used to partially mesh the external teeth with the internal teeth; as well as A support bearing is configured to allow the rigid wheel and the flexible wheel to rotate relative to each other. The support bearing includes an outer bearing ring and an inner bearing ring disposed within the outer bearing ring. The inner bearing ring and the outer bearing ring have a first groove for mounting a first rolling element and a second groove for mounting a second rolling element. The first groove and the second groove are spaced apart along the axial direction of the wave generator. Wherein, the first mounting part is connected to the inner bearing ring along the axial direction of the wave generator, the first mounting part is connected to the end of the inner tooth part away from the inner bearing ring, the inner tooth part includes a thin-walled section protruding from the first mounting part, the width of the thin-walled section is Lc1, the width of the inner tooth part is Lc, satisfying: 0.6*Lc≤Lc1≤0.9*Lc.

20. The harmonic reducer according to claim 19, wherein: The maximum wall thickness of the thin-walled section is Tc, and the inner diameter of the flexible wheel is Df, satisfying: 0.015*Df≤Tc≤0.05*Df.

21. The harmonic reducer according to claim 19 or 20, wherein: The connection between the thin-walled section and the first mounting part is constructed as a curve, which consists of at least two circular arc segments. The curve connects to the outer side of the thin-walled section at point a and to the first mounting part at point e. Along the axial direction, the distance from point a to point e is Lwa, which satisfies: 0.1*Lc1≤Lwa≤0.3*Lc1.

22. The harmonic reducer according to claim 21, wherein: The curve has points b, c and d. The distance from point a to point b is Lwb, the distance from point b to point c is Lwc, and the distance from point c to point d is Lwd. Lwb = Lwc = Lwd = Lwa / 4. as well as Along the radial direction of the rigid wheel, the distances from points b, c, d, and e to point a are Lrb, Lrc, Lrd, and Lre, respectively, where Lrb < Lrc < Lrd < Lre, satisfying: 0.1*Tc ≤ Lre ≤ 0.4*Tc, and Lrb + Lrc + Lrd ≤ Lre / 2.

23. The harmonic reducer according to any one of claims 19 to 22, wherein: The tooth root wall thickness of the flexure is Tf, the inner diameter of the flexure is Df, and the reduction ratio of the harmonic reducer is R, satisfying: 0.0043ln(R)-0.0061≤Tf / Df≤0.005ln(R)-0.0036.

24. The harmonic reducer according to any one of claims 1 to 23, wherein: Along the axial direction, the effective width of the flexible wheel is Lf, which satisfies: 0.45*Lf≤Lc≤0.65*Lf.

25. The harmonic reducer according to any one of claims 19 to 24, wherein: The outer bearing ring includes a second mounting portion and a protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring is provided with a groove opposite to the protrusion, and the two ends of the groove along the axial direction are respectively the first inner raceway and the second inner raceway. as well as The first inner raceway and the first outer raceway are arranged opposite each other to form the first groove, and the second inner raceway and the second outer raceway are arranged opposite each other to form the second groove.

26. The harmonic reducer according to claim 25, wherein: The inner bearing ring includes a first ring body and a second ring body connected to each other. The first inner raceway is located outside the first ring body and close to the second ring body, and the second inner raceway is located outside the second ring body and away from the first ring body. The second ring body is connected to the rigid wheel.

27. The harmonic reducer according to claim 26, wherein: The outer side of the thin-walled section abuts against the inner side of the second ring body; along the axial direction, the end of the second ring body away from the first ring body abuts against the end of the first mounting portion facing the thin-walled section.

28. Industrial robots, including: The harmonic reducer includes any one of claims 1 to 27.

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