Harmonic speed reducer and industrial robot

Abstract

The invention discloses a harmonic speed reducer and an industrial robot, and relates to the technical field of speed reducers, the harmonic speed reducer comprises a flexible gear, a rigid gear, a wave generator and a bearing device, the bearing device comprises an inner bearing ring, a first outer bearing ring, a second outer bearing ring, a plurality of first rolling bodies and a plurality of second rolling bodies, the inner bearing ring is fixedly connected with the rigid wheel and is provided with a first raceway and a second raceway, the first outer bearing ring and the second outer bearing ring are fixedly connected with the flange part, the first outer bearing ring is provided with a third raceway, the second outer bearing ring is provided with a fourth raceway, the first rolling body is installed between the first raceway and the third raceway, and the second rolling body is installed between the second raceway and the third raceway. The second rolling body is installed between the second raceway and the fourth raceway, the raceways are all complete raceways, the bearing capacity of the harmonic speed reducer can be effectively improved by arranging the structure of the two sets of complete raceways and the two sets of rolling bodies, the assembling efficiency between the bearing device and the rigid gear and the assembling efficiency between the bearing device and the flexible gear are improved while the structural compactness of the whole machine is kept, and production scheduling is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of speed reducer, in particular to a harmonic reducer and an industrial robot. BACKGROUND

[0002] In the related art, the harmonic reducer generally adopts a single-row crossed roller bearing as a supporting bearing. In order to facilitate the filling of rollers during bearing assembly, a roller filling port needs to be arranged on the inner ring or the outer ring of the crossed roller bearing. Due to the design of the roller filling port, the integrity of the raceway of the crossed roller bearing is destroyed, which affects the load capacity of the supporting bearing, so that the harmonic reducer cannot meet the requirements of load capacity and vibration noise while maintaining the compactness of the overall structure. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a harmonic reducer which can improve the load capacity and vibration noise while maintaining the compactness of the overall structure.

[0004] The present application also proposes an industrial robot having the above harmonic reducer.

[0005] According to the harmonic reducer of the first aspect of the present application, the harmonic reducer comprises: a rigid gear provided with an inner tooth portion; a flexible gear comprising a barrel portion and a flange portion, the barrel portion being provided with an outer tooth portion matched with the inner tooth portion; a wave generator coaxially installed in an inner hole of the flexible gear; a bearing device for supporting the rigid gear and the flexible gear to be relatively rotatable, the bearing device comprising an inner bearing ring, a first outer bearing ring, a second outer bearing ring, a plurality of first rolling elements and a plurality of second rolling elements; the inner bearing ring is fixedly connected with the rigid gear, the inner bearing ring is provided with a first raceway and a second raceway at two ends thereof away from the rotation axis of the wave generator, the first raceway and the second raceway are annular and arranged in a spaced manner; the first outer bearing ring, the second outer bearing ring and the flange portion are fixedly connected, the first outer bearing ring is provided with a third raceway located outside the first raceway and opposite to the first raceway, the second outer bearing ring is provided with a fourth raceway located outside the second raceway and opposite to the second raceway; a plurality of the first rolling elements are installed in a first annular space formed between the first raceway and the third raceway, and a plurality of the second rolling elements are installed in a second annular space formed between the second raceway and the fourth raceway.

[0006] According to the harmonic reducer of the present application, at least the following beneficial effects are achieved: The bearing device is provided with the bearing device for achieving convenient assembly with the rigid wheel and the flexible wheel, the bearing device comprises an inner bearing ring, a first outer bearing ring, a second outer bearing ring, a plurality of first rolling bodies and a plurality of second rolling bodies, the inner bearing ring is fixedly connected with the rigid wheel and is provided with a first raceway and a second raceway at two ends away from the rotating axis respectively, the first outer bearing ring, the second outer bearing ring and the flange part are fixedly connected, the first outer bearing ring is provided with a third raceway opposite to the first raceway, the second outer bearing ring is provided with a fourth raceway opposite to the second raceway, the plurality of first rolling bodies are installed in a first annular space formed between the first raceway and the third raceway, the plurality of second rolling bodies are installed in a second annular space formed between the second raceway and the fourth raceway, and the raceways in the first annular space and the raceways in the second annular space are complete raceways, the structure of the two sets of complete raceways and the two sets of rolling bodies can effectively improve the bearing capacity of the harmonic reducer, the assembly efficiency between the bearing device and the rigid wheel and the flexible wheel is improved while the compactness of the whole machine structure is maintained, and production scheduling is facilitated.

[0007] According to some embodiments of the present application, the inner hole diameter of the flexible wheel is Df, the maximum cross-sectional diameter of the first rolling body is Db1, and 0.07*Df≤Db1≤0.13*Df is satisfied.

[0008] According to some embodiments of the present application, the inner hole diameter of the flexible wheel is Df, and the diameter of a circle with the centers of the plurality of first rolling bodies in a direction perpendicular to the rotating axis is Db2, and 1.3*Df≤Db2≤1.7*Df is satisfied.

[0009] According to some embodiments of the present application, the minimum distance between the end wall of the one end of the barrel part away from the flange part and the flange part is Lf, the maximum distance between the center of the first rolling body and the center of the second rolling body in a direction parallel to the rotating axis is L1, and 0.2*Lf≤L1≤0.28*Lf is satisfied.

[0010] According to some embodiments of the present application, the minimum distance between the end wall of the one end of the barrel part away from the flange part and the flange part is Lf, the first outer bearing ring is provided with a first end face, the first end face abuts against the flange part, the maximum distance between the first end face and the center of the first rolling body is L2, and 0.24*Lf≤L2≤0.34*Lf is satisfied.

[0011] According to some embodiments of the present application, in a cross section passing through the rotating axis, the outer contour line of the first raceway is a first curve, the first curve comprises a first circular arc segment and a first modified segment, and the first modified segment is a non-circular arc.

[0012] According to some embodiments of the present invention, the radius of the first arc segment is Ri, 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 in the direction of the second rolling element, the Y-axis is perpendicular to the X-axis and points in the direction of the rotation axis, and the first curve satisfies the equation: ρi = Ri+ ki *Ri*[sin(90°*θ / βi)-1], when 0°≤θ≤βi; ρi = Ri, when θ>βi; Where, Ri = (0.505-0.515)*Db1, ki = 0.002-0.004, βi=20°-30°.

[0013] According to some embodiments of the present invention, within a cross section passing through the axis of rotation, the outer contour of the third raceway is a second curve, the second curve including a second circular arc segment and a second modified segment, the second modified segment being a non-circular arc.

[0014] According to some embodiments of the present invention, the radius of the second arc segment is Ro, 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 away from the second rolling element, the Y-axis is perpendicular to the X-axis and points away from the rotation axis, and the second curve satisfies the equation: ρo = Ro+ko *Ro*[sin(90°*θ / βo)-1], when 0°≤θ≤βo; ρo = Ro, when θ > βo; Among them, Ro = (0.505-0.515)*Db1, ko=0.002-0.004, βo=20°-30°.

[0015] According to some embodiments of the present invention, the first outer bearing ring has a first step on the side facing the second outer bearing ring, and the second outer bearing ring is positioned and connected to the first step; the first outer bearing ring and the second outer bearing ring are connected by a first fastener; and / or, the rigid wheel is connected to the side of the inner bearing ring near the second raceway, the rigid wheel has a second step on the side facing the inner bearing ring, and the inner bearing ring is positioned and connected to the second step; the rigid wheel and the inner bearing ring are connected by a second fastener.

[0016] According to some embodiments of the present application, a first oil storage space is formed between the bearing device and the flexspline, a second oil storage space is formed between the outer bearing ring and the inner bearing ring, the outer bearing ring and the inner bearing ring are provided with a first gap on one side of the second oil storage space close to the first oil storage space, and the outer bearing ring and the rigid spline are provided with a second gap on one side of the second oil storage space away from the first oil storage space; the harmonic reducer further comprises a first oil seal and a second oil seal, the first oil seal is installed in the first gap and is used to prevent exchange of lubricants in the first oil storage space and the second oil storage space, and the second oil seal is installed in the second gap and is used to prevent the lubricants in the second oil storage space from overflowing outward.

[0017] According to some embodiments of the present application, the inner wall of the first outer bearing ring is provided with a protrusion extending towards the rotation axis, the inner bearing ring is provided with a stepped portion spaced apart from the protrusion, and the first gap is formed between the protrusion and the stepped portion; the first oil seal comprises a mounting ring and a first lip, the mounting ring is fixedly connected to the protrusion, and the first lip is connected to the mounting ring and extends in the first gap to seal the first gap.

[0018] According to some embodiments of the present application, the first oil seal further comprises a second lip, the mounting ring comprises a first ring body and a second ring body, the first ring body is clamped to an end of the protrusion towards one end of the rotation axis, the second ring body is connected to the first ring body and extends towards the rotation axis, the second ring body is spaced apart from the inner bearing ring, and the second lip is connected to the second ring body and extends towards the inner bearing ring to seal the gap between the second ring body and the inner bearing ring.

[0019] According to some embodiments of the present application, the first ring body is provided with a stop shoulder located on a side wall of the protrusion towards the inner bearing ring to limit the first oil seal from being pulled out in a direction away from the inner bearing ring.

[0020] The industrial robot according to the second aspect of the embodiments of the present application comprises the harmonic reducer according to the above embodiments.

[0021] The industrial robot according to the embodiments of the present application has at least the following beneficial effects: The harmonic reducer adopting the first aspect embodiment, the harmonic reducer is through setting up the bearing device that realizes the convenient assembly with the rigid wheel and the flexible wheel, the bearing device includes inner bearing ring, first outer bearing ring, second outer bearing ring, multiple first rolling elements and multiple second rolling elements, the inner bearing ring is fixedly connected with the rigid wheel and is equipped with first raceway and second raceway at the two ends along the rotation axis, the first outer bearing ring, the second outer bearing ring and the flange part are fixedly connected, the first outer bearing ring is equipped with third raceway opposite the first raceway, the second outer bearing ring is equipped with fourth raceway opposite the second raceway, multiple first rolling elements are installed in the first annular space formed between the first raceway and the third raceway, multiple second rolling elements are installed in the second annular space formed between the second raceway and the fourth raceway, and the raceway in the first annular space and the raceway in the second annular space are complete raceways, the structure of setting up two complete raceways and two groups of rolling elements can effectively improve the carrying capacity of the harmonic reducer, while maintaining the compactness of the whole machine structure, the assembly efficiency between the bearing device and the rigid wheel, the flexible wheel is improved, and production is facilitated.

[0022] Additional aspects and advantages of the application will be set forth in part in the following description, will become apparent from the following description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will be further described below in conjunction with the drawings and examples, wherein: Figure 1 The structure sectional view of the harmonic reducer of one embodiment of the application is shown in the figure. Figure 2 The sectional view of the first oil seal of the embodiment shown in the figure is shown in the figure. Figure 1 The local sectional view of the inner bearing ring, the outer bearing ring and the rigid wheel in the figure is shown in the figure, wherein the rolling elements are shown in a reduced manner in order to show the matching relationship of the raceway and the rolling elements. Figure 3 The local enlarged view of the harmonic reducer shown in the figure is shown in the figure. Figure 1 The enlarged view of A in the figure is shown in the figure, wherein the first oil seal of one embodiment is shown. Figure 4 Figure 3 The enlarged view of A in the figure is shown in the figure, wherein the first oil seal of another embodiment is shown. Figure 5 The sectional view of the first oil seal of the embodiment shown in the figure is shown in the figure. Figure 3 The labeling diagram of various parameters of the harmonic reducer shown in the figure is shown in the figure. Figure 6 Figure 5 The main view of the inner bearing ring of the harmonic reducer of one embodiment of the application is shown in the figure. Figure 7 The main view of the inner bearing ring of the harmonic reducer of one embodiment of the application is shown in the figure. Figure 1 The main view of the inner bearing ring of the harmonic reducer of one embodiment of the application is shown in the figure. Figure 8 The main view of the inner bearing ring of the harmonic reducer of one embodiment of the application is shown in the figure. ​​Figure 9 for Figure 8 Enlarged view of point B in the middle; Figure 10 This is a cross-sectional view of the outer bearing ring in a harmonic reducer according to an embodiment of the present invention; Figure 11 for Figure 10 Enlarged view of point C in the middle; Figure 12 This is a graph showing the relationship between the ratio of Db1 to Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing device, and the weight of the whole machine. Figure 13 This is a graph showing the relationship between the ratio of Db2 to Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing device, and the weight of the whole machine. Figure 14 This is a graph showing the relationship between the ratio of L1 to Lf in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing device, and the weight of the entire machine. Figure 15 This is a graph showing the relationship between the ratio of L2 to Lf in a harmonic reducer according to an embodiment of the present invention and the allowable torque and main body length of the bearing device; Figure 16 This is a comparison diagram of the overturning moment stiffness before and after raceway modification in a harmonic reducer according to an embodiment of the present invention. Figure 17 This is a front view of the inner bearing ring in a harmonic reducer according to another embodiment of the present invention; Figure 18 for Figure 17 Enlarged view at point D; Figure 19 This is a cross-sectional view of the outer bearing ring in a harmonic reducer according to another embodiment of the present invention; Figure 20 for Figure 19 Enlarged view at point E in the middle; Figure 21 This is a cross-sectional view of the flexible wheel and rigid wheel in a harmonic reducer according to an embodiment of the present invention; Figure 22 for Figure 21 Enlarged sectional view of the external teeth shown; Figure 23 This is a cross-sectional view of a portion of the external gear section in a harmonic reducer according to an embodiment of the present invention.

[0024] Icon labels: Flexible wheel 100; cylindrical part 110; external toothed part 111; diaphragm part 120; flange part 130; protruding tooth 114; third shaping section 1141; first inclined surface 11411; intermediate section 1142; fourth shaping section 1143; second inclined surface 11431; third inclined surface 1144; fourth inclined surface 1145; Rigid wheel 200; internal gear 210; second step 220; Wave generator 300; Flexible bearing 310; Cam 320; Bearing assembly 400; inner bearing ring 410; first raceway 411; second raceway 412; boss 413; step portion 414; horizontal plane 4141; vertical plane 4142; first surface texture 415; first recess 4151; second surface texture 416; outer bearing ring 420; first outer bearing ring 421; third raceway 4211; protrusion 4212; inner hole surface 4213; right end face 4214; first step 4215; first end face 4216; first... Three-surface texture 4217; third recess 4218; second outer bearing ring 422; fourth raceway 4221; second end face 4222; fourth surface texture 4223; groove 423; second oil storage space 430; first gap 440; second gap 450; first rolling element 460; second rolling element 470; first curve 480; first arc segment 481; first modified segment 482; second curve 490; second arc segment 491; second modified segment 492; First oil storage space: 500; First oil seal 600; mounting ring 610; first ring body 611; second ring body 612; shoulder 613; first lip 620; second lip 630; third gap 640; Second oil seal 700; Rotation axis O; center line of symmetry Q. Detailed Implementation

[0025] Embodiments of the present invention 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 the present invention, and should not be construed as limiting the present invention.

[0026] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0027] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0028] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0029] Harmonic reducers, as a type of precision reducer, possess advantages such as compact structure, small size, light weight, high transmission ratio and load capacity, and high transmission accuracy. They are widely used in industries such as electronics, aerospace, robotics, and automation. As the application market for harmonic reducers expands and new industries and operating conditions are continuously explored, the market is constantly demanding higher performance from harmonic reducers in terms of high torque, high overturning moment, high rigidity, low leakage, and low vibration.

[0030] Reference Figure 1 As shown, a harmonic reducer according to an embodiment of the present invention includes a flexible wheel 100, a rigid wheel 200, and a wave generator 300. The flexible wheel 100 is coaxially mounted inside the rigid wheel 200, and the wave generator 300 is coaxially mounted in the inner hole of the flexible wheel 100. The flexible wheel 100 includes a cylindrical portion 110, a diaphragm portion 120, and a flange portion 130. The cylindrical portion 110 is located at the end of the flexible wheel 100 near the rigid wheel 200. The diaphragm portion 120 is connected to the end of the cylindrical portion 110 away from the rigid wheel 200 and extends outward from the cylindrical portion 110. The flange portion 130 is connected to the outer periphery of the diaphragm portion 120. The cylindrical portion 110 of the flexible wheel 100 is provided with a flexible external tooth portion 111, and the rigid wheel 200 is provided with a rigid internal tooth portion 210. The external tooth portion 111 and the internal tooth portion 210 mesh, forming a meshing clearance between the external tooth portion 111 and the internal tooth portion 210.

[0031] In this embodiment of the invention, the wave generator 300 is interference-fitted into the inner hole of the flexible wheel 100. The wave generator 300 is configured to engage the external tooth 111 with the internal tooth 210 when rotating. After the wave generator 300 is installed in the inner hole of the flexible wheel 100, it forces the flexible wheel 100 to undergo elastic deformation and become elliptical. During the operation of the harmonic reducer, the wave generator 300 rotates at high speed, thereby causing the flexible wheel 100 to undergo repeated deformation, causing the external tooth 111 of the flexible wheel 100 to engage with the internal tooth 210 of the rigid wheel 200. The engagement position of the external tooth 111 and the internal tooth 210 moves circumferentially along the rotation axis O of the wave generator 300, thereby realizing the relative deceleration motion between the flexible wheel 100 and the rigid wheel 200. The wave generator 300 includes a flexible bearing 310 and a cam 320. The flexible bearing 310 is sleeved on the outside of the cam 320, and the cam 320 is provided with a mounting position for connecting a drive device such as a motor.

[0032] Reference Figure 1 and Figure 2As shown, a harmonic reducer according to one embodiment of the present invention further includes a bearing assembly 400, which supports the rigid wheel 200 and the flexible wheel 100, and enables the rigid wheel 200 and the flexible wheel 100 to rotate relative to each other. The bearing assembly 400 is disposed around the outer side of the cylindrical portion 110, and includes an inner bearing ring 410 and an outer bearing ring 420. The inner bearing ring 410 is fixedly connected to the rigid wheel 200, and the outer bearing ring 420 is disposed around the outer side of the inner bearing ring 410 and fixedly connected to the flange portion 130. The inner bearing ring 410 and the outer bearing ring 420 can rotate relative to each other.

[0033] In this embodiment of the harmonic reducer, the outer bearing ring 420 includes a first outer bearing ring 421 and a second outer bearing ring 422. The first outer bearing ring 421 is connected to the flange portion 130, and the second outer bearing ring 422 is connected to the first outer bearing ring 421. The flange portion 130, the first outer bearing ring 421, and the second outer bearing ring 422 can be fixedly connected together using fasteners (e.g., screws, bolts, pins, etc.); alternatively, they can be fixed separately, i.e., the flange portion 130 and the first outer bearing ring 421 are fixedly connected by one set of fasteners, and the first outer bearing ring 421 and the second outer bearing ring 422 are fixedly connected by another set of fasteners. The appropriate fasteners should be selected based on the assembly requirements and load requirements of the harmonic reducer in actual use; specific limitations are not specified here.

[0034] Continue to refer to Figure 1 and Figure 2 As shown, the inner bearing ring 410 is provided with a first raceway 411 and a third raceway 4211 at two ends opposite to the rotation axis O of the wave generator 300. Both the first raceway 411 and the third raceway 4211 are annular and are arranged at intervals in the direction of the rotation axis O.

[0035] The first outer bearing ring 421 has a third raceway 4211 located outside the first raceway 411 (i.e., the side opposite to the third raceway 4211) and opposite to the first raceway 411. The second outer bearing ring 422 has a fourth raceway 4221 located outside the third raceway 4211 (i.e., the side opposite to the first raceway 411) and opposite to the third raceway 4211. Both the third raceway 4211 and the fourth raceway 4221 are annular. A first annular space is formed between the first raceway 411 and the third raceway 4211, and a plurality of first rolling elements 460 are installed in the first annular space. A second annular space is formed between the third raceway 4211 and the fourth raceway 4221, and a plurality of second rolling elements 470 are installed in the second annular space.

[0036] This embodiment of the invention employs two sets of rolling elements, consisting of multiple first rolling elements 460 and multiple second rolling elements 470. Compared to single-row crossed roller bearings in related technologies, this improves the load-bearing capacity of the bearing assembly 400. Furthermore, the structure of the inner bearing ring 410, the first outer bearing ring 421, and the second outer bearing ring 422 facilitates the assembly of the harmonic reducer and makes it easier to adapt to different loads. It is understood that the first rolling element 460 can be a sphere, or a cylindrical or conical shape; the second rolling element 470 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 460 and the second rolling elements 470 can be made of metal materials such as steel.

[0037] In this embodiment of the invention, the first outer bearing ring 421, the second outer bearing ring 422, and the inner bearing ring 410 can be assembled close to each other along the rotation axis O, and multiple first rolling elements 460 and multiple second rolling elements 470, as well as mounting brackets and other accessories, can be installed simultaneously until the first outer bearing ring 421 and the second outer bearing ring 422 abut and are fixed in the direction of the rotation axis O, thereby forming a stable bearing device 400 in cooperation with the inner bearing ring 410. Furthermore, the flexible wheel 100 and the rigid wheel 200 are respectively installed at both ends of the bearing device 400, enabling convenient installation. The first raceway 411 and the third raceway 4211 in the first annular space, and the third raceway 4211 and the fourth raceway 4221 in the second annular space are all complete raceways. By setting two sets of complete raceways and two sets of rolling elements, the load-bearing capacity of the harmonic reducer can be effectively improved while maintaining the compactness of the overall structure. The rigid wheel 200 and flexible wheel 100, along with the bearing device 400, can be produced separately and then assembled later, which facilitates production scheduling. Furthermore, it improves the assembly efficiency between the bearing device 400 and the rigid wheel 200 and flexible wheel 100, thereby increasing the production efficiency of the harmonic reducer.

[0038] Reference Figure 2 As shown, the first outer bearing ring 421 has a first step 4215 on the side facing the second outer bearing ring 422. The second outer bearing ring 422 is positioned and connected to the first step 4215, thereby achieving axial and radial positioning between the first and second outer bearing rings 421 and 422, improving assembly efficiency and accuracy. The first outer bearing ring 421 and the second outer bearing ring 422 are connected by multiple first fasteners, which are arranged at intervals around the first outer bearing ring 421. It can be understood that the first fasteners can be screws, bolts, pins, etc.

[0039] Reference Figure 2As shown, the rigid wheel 200 is connected to the inner bearing ring 410 on the side near the third raceway 4211. A second step 220 is provided on the side of the rigid wheel 200 facing the inner bearing ring 410, and the inner bearing ring 410 is positioned and connected to the second step 220. This achieves axial and radial positioning between the rigid wheel 200 and the inner bearing ring 410, improving assembly efficiency and accuracy. The rigid wheel 200 and the inner bearing ring 410 are connected by multiple second fasteners, which are arranged at intervals around the rigid wheel 200. It is understood that the second fasteners can be screws, bolts, pins, etc.

[0040] Reference Figure 3 As shown, the installation direction of the second fastener is opposite to that of the first fastener. For example, the first fastener is installed from left to right, and the second fastener is installed from right to left, which facilitates the assembly between the bearing device 400 and the flexible wheel 100 and rigid wheel 200.

[0041] Reference Figure 2 and Figure 3 As shown, a first oil storage space 500 is formed between the bearing assembly 400 and the cylindrical portion 110 and diaphragm 120 of the flexible wheel 100, and the first oil storage space 500 is connected to the meshing clearance. During operation, the harmonic reducer... Figure 3 The dashed arrows indicate the flow direction of the lubricant: specifically, from the inner bore of the flexure 100 to the meshing gap, and then to the first oil storage space 500. The lubricant lubricates the wave generator 300 at the inner bore of the flexure 100, further acts on the gear pair between the flexure 100 and the rigid gear 200, and finally accumulates in the first oil storage space 500. The lubricant in the first oil storage space 500 can continuously lubricate the gear pair.

[0042] A second oil storage space 430 is formed between the outer bearing ring 420 and the inner bearing ring 410. The second oil storage space 430 is used to lubricate the raceways and rolling elements within the bearing assembly 400. To facilitate the assembly of the bearing assembly 400, gaps exist on both sides of the mating position of the outer bearing ring 420 and the inner bearing ring 410. These gaps include a first gap 440 between the outer bearing ring 420 and the inner bearing ring 410 on the side of the second oil storage space 430 closer to the first oil storage space 500, and a second gap 450 between the outer bearing ring 420 and the rigid wheel 200 on the side of the second oil storage space 430 away from the first oil storage space 500.

[0043] One embodiment of the harmonic reducer of the present invention further includes a first oil seal 600 and a second oil seal 700. The first oil seal 600 is installed within a first gap 440 and serves to prevent the exchange of lubricant between the first oil storage space 500 and the second oil storage space 430. The second oil seal 700 is installed within a second gap 450 and serves to prevent lubricant in the second oil storage space 430 from overflowing from the outer peripheral wall of the rigid wheel 200 to the outside. The inner hole of the second oil seal 700 maintains contact with the outer peripheral wall of the rigid wheel 200, and during operation, the two rotate relative to each other, forming a radial contact seal. The second oil seal 700 is generally a conventional skeleton oil seal.

[0044] Because iron powder and other foreign matter are easily generated when the external gear 111 and the internal gear 210 mesh, the iron powder and other foreign matter will mix into the lubricant and contaminate it. The contaminated lubricant has little effect on the flexible bearing 310, the internal gear 210 and the external gear 111, but has a greater impact on the bearing assembly 400, which is subjected to large contact stress. Therefore, the first oil seal 600 can prevent the lubricant containing iron powder and other foreign matter in the first oil storage space 500 from entering the second oil storage space 430, effectively preventing abnormal damage to the bearing assembly 400 and thus preventing premature failure, thereby improving the service life of the harmonic reducer.

[0045] With the combined action of the first oil seal 600 and the second oil seal 700, the second oil storage space 430 forms a sealed cavity, isolated from the first oil storage space 500. Therefore, the first oil storage space 500 and the second oil storage space 430 can use different lubricants. In particular, the lubricant of the bearing device 400 can be reasonably selected according to the performance and working conditions of the harmonic reducer, thereby improving the lubrication effect in the bearing device 400 and thus improving the overall performance of the harmonic reducer.

[0046] In addition, under the sealing effect of the first oil seal 600, the lubricant in the first oil storage space 500 cannot enter the second oil storage space 430, so that the grease in the harmonic reducer cannot leak from the outer peripheral wall of the wheel 200, thus improving the sealing performance of the harmonic reducer.

[0047] Reference Figure 2 and Figure 3 As shown, it can be understood that the end face of the second outer bearing ring 422 that is away from the first outer bearing ring 421 is the second end face 4222. The second end face 4222 is provided with a groove 423. A second gap 450 is formed between the bottom wall of the groove 423 and the outer peripheral wall of the rigid wheel 200. The second oil seal 700 is positioned and installed in the second gap 450 through the groove 423, making assembly simpler and more convenient.

[0048] Reference Figure 2As shown, a boss 413 is formed between the first raceway 411 and the third raceway 4211 in the inner bearing ring 410. The boss 413 can improve the structural strength of the first raceway 411 and the third raceway 4211. A channel is formed between the inner wall of the first outer bearing ring 421, the inner wall of the second outer bearing ring 422, and the boss 413. The channel is used to connect the first annular space and the second annular space, so that the lubricant can flow between the first annular space and the second annular space, thereby effectively lubricating the rolling elements and the raceways.

[0049] To prevent lubricant from the first oil storage space 500 from entering the second oil storage space 430, the first gap 440 includes at least two gaps that are angled to each other. (Refer to...) Figure 2 and Figure 3 As shown, the inner wall of the first outer bearing ring 421 extends toward the rotation axis O and has a protrusion 4212. The center of the protrusion 4212 is formed as a through hole. The inner bearing ring 410 has a stepped portion 414 spaced apart from the protrusion 4212. A first gap 440 is formed between the protrusion 4212 and the stepped portion 414. A first gap is formed between the inner hole surface 4213 of the protrusion 4212 and the horizontal surface 4141 of the stepped portion 414. A second gap is formed between the right end face 4214 of the protrusion 4212 and the vertical surface 4142 of the stepped portion 414. The first gap and the second gap are set at an angle to each other, for example, at a right angle. In one embodiment, the first oil seal 600 can be configured to seal the connection between the first gap and the second gap. In another embodiment, the first oil seal 600 can be configured to seal both the first gap and the second gap simultaneously, achieving a double seal. In another embodiment, the first oil seal 600 can be configured to seal the second gap, with the first gap acting as a labyrinth seal to prevent lubricant from entering the second gap. During operation, the lip of the first oil seal 600 and the inner bearing ring 410 remain in contact, with relative rotational motion between them, forming an axial contact seal.

[0050] Reference Figure 4 As shown, in one embodiment of the present invention, the first oil seal 600 includes a mounting ring 610 and a first lip 620. The mounting ring 610 is fixedly connected to the protrusion 4212. The mounting ring 610 can be interference-fitted into the through hole of the protrusion 4212, or installed into the through hole by means of bonding, screwing, etc. As another embodiment, the mounting ring 610 can also be fixedly connected to the right end face 4214 (the end opposite to the flange portion 130) or the left end wall (the end facing the flange portion 130) of the protrusion 4212. The first lip 620 is connected to the mounting ring 610. The first lip 620 extends from the mounting ring 610 into the first gap 440 and seals the first gap 440, thereby achieving stable installation of the first oil seal 600 and effective sealing of the first gap 440.

[0051] To improve the stability of the first oil seal 600, the mounting ring 610 is integrally manufactured from metal material, for example, using a stamping process, making the overall structure of the first oil seal 600 more stable. The first lip 620 is configured as a sealing ring that wraps around at least a portion of the outer wall of the mounting ring 610, and is configured to seal the connection between the first and second segments of the first gap 440. The sealing ring is integrally manufactured from rubber material before being installed onto the mounting ring 610, or it is integrally injection molded with the mounting ring 610, which can achieve a better sealing effect.

[0052] Reference Figure 5 and Figure 6 As shown, in another embodiment of the present invention, the first oil seal 600 includes a first lip 620 and a second lip 630, and the mounting ring 610 includes a first ring body 611 and a second ring body 612. The first ring body 611 is snapped into the end of the protrusion 4212 facing the rotation axis O. The first lip 620 is fixedly connected to the first ring body 611 and is used to seal the first gap 440.

[0053] The second ring 612 is connected to the first ring 611 and extends toward the rotation axis O. A third gap 640, communicating with the first gap 440, is formed between the second ring 612 and the left end face of the inner bearing ring 410. The third gap 640 and the first section of the first gap 440 are set at an angle to each other, thus forming a labyrinth seal. The second lip 630 is fixedly connected to the second ring 612 and extends toward the inner bearing ring 410, thereby sealing the third gap 640 between the second ring 612 and the inner bearing ring 410, further inhibiting lubricant from entering the second oil storage space 430. This embodiment achieves a two-stage seal through the first lip 620 and the second lip 630, forming a labyrinth seal composed of the first gap 440 and the third gap 640. Therefore, it can better prevent the exchange of lubricant in the first oil storage space 500 and the second oil storage space 430, thus protecting the lifespan of the bearing assembly 400.

[0054] Continue to refer to Figure 5 and Figure 6 As shown, it can be understood that the first ring body 611 is provided with a shoulder 613. The shoulder 613 is located on the side wall (i.e., the right end face 4214) of the protrusion 4212 facing the inner bearing ring 410. The shoulder 613 can restrict the first oil seal 600 from coming off in a direction away from the inner bearing ring 410, thereby improving the installation stability of the first oil seal 600.

[0055] To improve the stability of the first oil seal 600, the first ring 611, the second ring 612, and the shoulder 613 are integrally manufactured from metal materials, for example, using stamping or bending processes, making the overall structure of the first oil seal 600 more stable. The first lip 620 and the second lip 630 are configured as sealing rings that wrap around at least part of the outer wall of the mounting ring 610. The sealing rings are integrally manufactured from rubber materials and then installed onto the mounting ring 610, or integrally injection molded with the mounting ring 610. Therefore, the sealing rings can achieve a better sealing effect on the first gap 440 and the third gap 640.

[0056] Reference Figure 7 As shown, the inner diameter of the flexible wheel 100 is defined as Df. The maximum cross-sectional diameter of the first rolling element 460 is defined as Db1, which is the diameter of the largest cross-section of the first rolling element 460 perpendicular to the rotation axis O. For example, when the first rolling element 460 is a sphere, Db1 is the diameter of the sphere; when the first rolling element 460 is a cylinder, Db1 is the diameter of the largest cross-section among all cross-sections perpendicular to the axis of the cylinder. Multiple first rolling elements 460 are arranged circumferentially at intervals along the rotation axis O. The diameter of the circle containing the centers of the multiple first rolling elements 460 in the direction perpendicular to the rotation axis O is defined as Db2.

[0057] The minimum distance between the end wall of the cylinder 110 away from the flange 130 and the flange 130 is defined as Lf. Lf is related to the performance of the flexure 100; the larger Lf is, the greater the flexibility of the flexure 100; conversely, the smaller Lf is, the greater the rigidity of the flexure 100.

[0058] Multiple second rolling elements 470 are arranged axially at intervals along the rotation axis O. The maximum distance between the centers of the first rolling element 460 and the second rolling element 470, which are parallel to the rotation axis O, is defined as L1. L1 is related to the span of the bearing assembly 400; the larger L1 is, the larger the span, and the better the anti-overturning capability of the bearing assembly 400; conversely, the smaller L1 is, the smaller the span, and the worse the anti-overturning capability of the bearing assembly 400.

[0059] The first outer bearing ring 421 is provided with a first end face 4216, which abuts against the flange portion 130. The maximum distance between the first end face 4216 and the center of the first rolling element 460 is L2.

[0060] Reference Figure 7 As shown, it can be understood that the maximum cross-sectional diameter Db1 of the first rolling element 460 satisfies: 0.07*Df≤Db1≤0.13*Df; the value of Db1 can be: 0.07*Df, 0.09*Df, 0.1*Df, 0.11*Df, 0.13*Df, etc.Figure 12 This diagram illustrates the relationship between the ratio of Db1 to Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing assembly 400, and the overall weight. It should be noted that the allowable torque is the maximum overturning torque that the bearing assembly 400 can withstand during normal operation. (Refer to...) Figure 12 As shown, when Db1 / Df is less than 0.07, the overall weight of the harmonic reducer remains basically unchanged, but the allowable torque decreases rapidly, failing to meet the usage requirements. When Db1 / Df is greater than 0.13, although the allowable torque continues to increase, the overall weight increases rapidly, also failing to meet the usage requirements. Therefore, by balancing the requirements of the overall weight and allowable torque of the harmonic reducer, setting the maximum cross-sectional diameter Db1 of the first rolling element 460 between 0.07*Df and 0.13*Df can simultaneously meet the requirements of the maximum overturning moment and the overall weight.

[0061] Reference Figure 7 As shown, it can be understood that, in the direction perpendicular to the rotation axis O, the diameter Db2 of the circle containing the center of the multiple first rolling elements 460 satisfies: 1.3*Df≤Db2≤1.7*Df; the value of Db2 can be: 1.3*Df, 1.5*Df, 1.6*Df, 1.7*Df, etc. Figure 13 This diagram illustrates the relationship between the ratio of Db2 to Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing assembly 400, and the overall weight. It should be noted that the allowable torque is the maximum overturning torque that the bearing assembly 400 can withstand during normal operation. (Refer to...) Figure 13 As shown, when Db2 / Df is less than 1.3, the overall weight of the harmonic reducer remains basically unchanged, 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 increases rapidly, also failing to meet the usage requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer, setting the diameter Db2 of the circle containing the center of the first rolling element 460 between 1.3*Df and 1.7*Df can simultaneously meet the requirements of the maximum overturning moment and the overall weight requirements.

[0062] Reference Figure 7 As shown, it can be understood that the maximum distance L1 between the center of the first rolling element 460 and the center of the second rolling element 470 on the axis of rotation O satisfies: 0.2*Lf≤L1≤0.28*Lf; the value of L1 can be: 0.2*Lf, 0.22*Lf, 0.25*Lf, 0.27*Lf, 0.28*Lf. Figure 14This diagram illustrates the relationship between the ratio of L1 to Lf in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing assembly 400, and the overall weight. It should be noted that the allowable torque is the maximum overturning torque that the bearing assembly 400 can withstand during normal operation. (Refer to...) Figure 14 As shown, when L1 / Lf is less than 0.2, the overall weight of the harmonic reducer changes relatively smoothly, but the allowable torque decreases rapidly, failing to meet the usage requirements. When L1 / Lf is greater than 0.28, although the allowable torque continues to increase, the overall weight also increases rapidly, failing to meet the usage requirements. Therefore, by balancing the requirements of the overall weight and allowable torque of the harmonic reducer, the maximum distance L1 between the center of the first rolling element 460 and the center of the second rolling element 470, which are parallel to the rotation axis O, is set between 0.2*Lf and 0.28*Lf, which can simultaneously meet the requirements of the maximum overturning moment and the overall weight.

[0063] Reference Figure 7 As shown, it can be understood that the maximum distance between the center of the first end face 4216 and the center of the first rolling element 460 is L2, which satisfies: 0.24*Lf≤L2≤0.34*Lf; the value of L2 can be: 0.24*Lf, 0.25*Lf, 0.3*Lf, 0.31*Lf, 0.34*Lf. Figure 15 This diagram illustrates the relationship between the ratio of L2 to Lf in a harmonic reducer according to an embodiment of the present invention, and the allowable torque and main body length of the bearing assembly 400. It should be noted that the allowable torque is the maximum overturning torque that the bearing assembly 400 can withstand during normal use, and the main body length is the maximum dimension of the assembly of the rigid wheel 200, the flexible wheel 100, and the bearing assembly 400 along the rotation axis O. (Refer to...) Figure 15 As shown, when L2 / Lf is less than 0.24, the main body length of the harmonic reducer 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, setting the maximum distance L2 between the center of the first end face 4216 and the first rolling element 460 to between 0.2*Lf and 0.28*Lf can simultaneously meet the requirements of the maximum overturning moment and the main body length.

[0064] Reference Figure 8 and Figure 9As shown, within the cross-section passing through the rotation axis O, the outer contour of the first raceway 411 is the first curve 480. Since the first raceway 411 is located outside the inner bearing ring 410 and is annular, the outer contour of the first raceway 411 in the front view of the inner bearing ring 410 is the same as the outer contour in the cross-section passing through the rotation axis O. For ease of description, this embodiment of the invention uses the front view of the inner bearing ring 410 as an example. Compared to the arc-shaped raceway in related technologies, the first raceway 411 in this embodiment is modified. Specifically, the first curve 480 includes a first arc segment 481 and a first modified segment 482, where the first modified segment 482 is non-arc. With the modified first raceway 411, the contact area between the first rolling element 460 and the first raceway 411 is larger when subjected to a larger overturning moment, which can reduce the contact stress between the first rolling element 460 and the first raceway 411, thereby improving the overall overturning moment and overturning moment rigidity of the bearing assembly 400.

[0065] Reference Figure 9 As shown, it can be understood that the radius of the first arc segment 481 is defined as Ri, and a coordinate system is established with the center of the first arc segment 481 as the origin. The X-axis is parallel to the rotation axis O and points in the direction of the second rolling element 470 (i.e., Figure 9 (in the right direction), the Y-axis is perpendicular to the X-axis and points in the direction of the rotation axis O (i.e., Figure 9 (in the downward direction), the first curve 480 satisfies the equation: ρi = Ri+ ki *Ri*[sin(90°*θ / βi)-1], when 0°≤θ≤βi; ρi = Ri, when θ>βi; Where Ri = (0.505-0.515)*Db1, ki = 0.002-0.004, for example, ki takes values ​​of 0.002, 0.003, 0.004; βi = 20°-30°, for example, βi takes values ​​of 20°, 25°, 30°.

[0066] By designing the first curve 480, the first raceway 411 is subjected to a large overturning moment, resulting in multi-point contact between the first rolling element 460 and the first raceway 411. This increases the contact position and contact area, reduces contact stress, and is significantly better than the single-point contact between the first rolling element 460 and the first raceway 411 in related technologies (before modification).

[0067] For example, when the bearing assembly 400 is subjected to force, both the first rolling element 460 and the first raceway 411 will deform. Before the deformation, the first rolling element 460 and the first raceway 411 will have single-point contact at a position of about 40°; however, after the deformation, the first rolling element 460 and the first raceway 411 will have contact not only at a position of about 40°, but also between 10° and 20°.

[0068] Figure 16 This is a comparison diagram of the overturning moment stiffness of the first raceway 411 before and after modification in a harmonic reducer according to an embodiment of the present invention. (Refer to...) Figure 16 As shown, after the first raceway 411 is modified, when the bearing assembly 400 is subjected to a large torque (such as...), Figure 16 (As shown, greater than 600 N·m), the angle at which the overturning moment is generated becomes smaller; according to the formula 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 the first raceway 411 of this embodiment of the invention is modified by the above equation, the overturning moment stiffness is improved to varying degrees, even up to 20%.

[0069] It is understood that in this embodiment, the first raceway 411 and the third raceway 4211 are symmetrical with respect to the center line Q of the first rolling element 460 and the second rolling element 470. The outer contour of the third raceway 4211 is the third curve. The third curve and the first curve 480 are symmetrical with respect to the center line Q of the first rolling element 460 and the second rolling element 470. Therefore, the equation of the first curve 480 can be used for understanding. To avoid repetition, it will not be described again here.

[0070] Reference Figure 10 and Figure 11 As shown, within the cross-section passing through the rotation axis O, the outer contour of the third raceway 4211 is the second curve 490. The second curve 490 includes a second arc segment 491 and a second modified segment 492, where the second modified segment 492 is non-arc. Compared to the arc-shaped raceways in related technologies, the third raceway 4211 in this embodiment is modified. With the modified third raceway 4211, when subjected to a large overturning moment, the contact area between the first rolling element 460 and the third raceway 4211 is larger, which can reduce the contact stress between the first rolling element 460 and the third raceway 4211, thereby improving the overall overturning moment and overturning moment rigidity bearing capacity of the bearing assembly 400.

[0071] Reference Figure 11 As shown, the radius of the second arc segment 491 is Ro. A coordinate system is established with the center of the second arc segment 491 as the origin. The X-axis is parallel to the rotation axis O and points away from the direction of the second rolling element 470 (i.e., Figure 11(in the left direction), the Y-axis is perpendicular to the X-axis and points away from the rotation axis O (i.e., Figure 11 (in the upward direction), the second curve 490 satisfies the equation: ρo = Ro+ko *Ro*[sin(90°*θ / βo)-1], when 0°≤θ≤βo; ρo = Ro, when θ > βo; Where Ro = (0.505-0.515)*Db1, ko = 0.002-0.004, for example, ko takes values ​​of 0.001, 0.003, 0.004; βo = 20°-30°, for example, βo takes values ​​of 20°, 25°, 30°.

[0072] In this embodiment of the invention, by designing the second curve 490, when the third raceway 4211 is subjected to a large overturning moment, the first rolling element 460 and the third raceway 4211 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 460 and the third raceway 4211 in related technologies (before modification).

[0073] For example, when the bearing assembly 400 is subjected to force, both the first rolling element 460 and the third raceway 4211 will deform. Before the deformation, the first rolling element 460 and the third raceway 4211 will have single-point contact at a position of about 40°; however, after the deformation, the first rolling element 460 and the third raceway 4211 will not only have contact at a position of about 40°, but will also have contact between 10° and 20°.

[0074] Figure 16 This is a comparison diagram of the overturning moment stiffness of the third raceway 4211 before and after modification in a harmonic reducer according to an embodiment of the present invention. (Refer to...) Figure 16 As shown, after the third raceway 4211 is modified, when the bearing assembly 400 is subjected to a large torque (such as...), Figure 16 (As shown, greater than 600 N·m), the angle at which the overturning moment is generated becomes smaller; according to the formula 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 the third raceway 4211 of this embodiment of the invention is modified by the above equation, the overturning moment stiffness is improved to varying degrees, even up to 20%.

[0075] It is understood that in this embodiment, the third raceway 4211 and the fourth raceway 4221 are symmetrical with respect to the center line Q of the first rolling element 460 and the second rolling element 470. The outer contour of the fourth raceway 4221 that cooperates with the second rolling element 470 is the fourth curve. The fourth curve and the second curve 490 are symmetrical with respect to the center line Q of the first rolling element 460 and the second rolling element 470. Therefore, the equation of the second curve 490 can be used for understanding. To avoid repetition, it will not be described again here.

[0076] Reference Figure 17 and Figure 18 As shown, in one embodiment of the harmonic reducer of the present invention, the first raceway 411 is provided with a first surface texture 415, which includes a plurality of spaced-apart first recesses 4151. The presence of the first recesses 4151 on the first raceway 411 reduces the contact area between the first rolling element 460 and the first raceway 411. This reduction in contact area helps to reduce the generation of abrasive particles, and the generated abrasive particles can be stored within the first recesses 4151, inhibiting their entry into the contact surface between the first raceway 411 and the first rolling element 460. This suppresses the abrasive particles from accelerating raceway wear and reduces the appearance of a white layer on the first raceway 411. The first surface texture 415 can also store lubricant. When the first rolling element 460 squeezes the first raceway 411, it will cause the first raceway 411 to undergo slight deformation, squeezing out the lubricant in the first recess 4151, which can play a role in supplementing lubrication, improving lubrication conditions, reducing the risk of fatigue fracture of the first raceway 411, thereby improving the overall vibration and noise performance of the harmonic reducer and enhancing the overall load-bearing capacity.

[0077] Reference Figure 18 As shown, it can be understood that the first recess 4151 is hemispherical, and its depth is between 2 μm and 10 μm. It can be understood that if the depth of the first recess 4151 is too small, for example, less than 2 μm, it is easily worn down by the first rolling element 460, reducing its ability to store lubricant and abrasive particles, and failing to reduce frictional loss during long-term use; furthermore, a depth that is too small makes machining difficult. If the depth of the first recess 4151 is too large, for example, greater than 10 μm, it easily leads to deterioration of the lubrication effect, making it difficult to form a continuous oil film on the surface of the first raceway 411.

[0078] The port diameter of the first recess 4151 is between 50 μm and 200 μm. When the port diameter of the first recess 4151 is less than 50 μm, its ability to store abrasive particles and lubricant is low. The port diameter of the first recess 4151 is related to the contact width between the first rolling element 460 and the first raceway 411. When the port diameter of the first recess 4151 is greater than 200 μm, which is greater than the contact width between the first rolling element 460 and the first raceway 411, the first rolling element 460 will not run smoothly, and wear will be aggravated.

[0079] Therefore, by designing the first recess 4151 according to the above parameters, the first recess 4151 can have a good ability to store abrasive particles and lubricant, and can improve the oil film carrying capacity.

[0080] Reference Figure 18 As shown, the first raceway 411 of this embodiment of the invention is provided with a first surface texture 415, and the total area of ​​the first surface texture 415 accounts for 10% to 20% of the area of ​​the first raceway 411. It is understood that if the total area of ​​the first surface texture 415 is too small, for example less than 10%, the effect of storing abrasive particles and lubricant is poor; while if the proportion is too large, for example greater than 20%, it can easily lead to accelerated wear. Therefore, a total area ratio of 10% to 20% for the first surface texture 415 enables the first raceway 411 to have good anti-friction capability and lubricant storage capability, solving the problem of white layer on the first raceway 411.

[0081] Reference Figure 17 and Figure 18 As shown, in one embodiment of the harmonic reducer of the present invention, the second raceway 412 is provided with a second surface texture 416, which can reduce the contact area between the first rolling element 460 and the second raceway 412, suppress the abrasive particles from accelerating raceway wear, and thus reduce the appearance of a white layer on the second raceway 412. The specific principle of this embodiment can be understood with reference to the first raceway 411, and to avoid repetition, it will not be specifically limited here.

[0082] Reference Figure 19 and Figure 20As shown, in one embodiment of the harmonic reducer of the present invention, the third raceway 4211 is provided with a third surface texture 4217, which includes a plurality of spaced third recesses 4218. The presence of the third recesses 4218 reduces the contact area between the first rolling element 460 and the third raceway 4211 due to the third surface texture 4217 on the third raceway 4211. This reduction in contact area helps reduce the generation of abrasive particles, and the generated abrasive particles can be stored within the third recesses 4218, inhibiting their entry into the contact surface between the third raceway 4211 and the first rolling element 460. This suppresses the abrasive particles from accelerating raceway wear and reduces the appearance of a white layer on the third raceway 4211. The third surface texture 4217 can also store lubricant. When the first rolling element 460 squeezes the third raceway 4211, it will cause the third raceway 4211 to undergo slight deformation, squeezing out the lubricant in the third recess 4218, which can play a role in supplementing lubrication, improving lubrication conditions, reducing the risk of fatigue fracture of the third raceway 4211, thereby improving the overall vibration and noise performance of the harmonic reducer and enhancing the overall load-bearing capacity.

[0083] Reference Figure 20 As shown, it is understood that the third recess 4218 is hemispherical, and its depth is between 2 μm and 10 μm. It is also understood that if the depth of the third recess 4218 is too small, for example less than 2 μm, it is easily worn down by the first rolling element 460, reducing its ability to store lubricant and abrasive particles, and failing to reduce frictional loss during long-term use; furthermore, a depth that is too small makes machining difficult. If the depth of the third recess 4218 is too large, for example greater than 10 μm, it easily leads to deterioration of the lubrication effect, making it difficult to form a continuous oil film on the surface of the third raceway 4211.

[0084] The port diameter of the third recess 4218 is between 50 μm and 200 μm. When the port diameter of the third recess 4218 is less than 50 μm, its ability to store abrasive particles and lubricant is low. The port diameter of the third recess 4218 is related to the contact width between the first rolling element 460 and the third raceway 4211. When the port diameter of the third recess 4218 is greater than 200 μm, which is greater than the contact width between the first rolling element 460 and the third raceway 4211, the first rolling element 460 will run unevenly, leading to increased wear.

[0085] Therefore, by designing the third recess 4218 according to the above parameters, the third recess 4218 can have a good ability to store abrasive particles and lubricant, and can improve the oil film carrying capacity.

[0086] Reference Figure 20As shown, the third raceway 4211 of this embodiment of the invention is provided with a third surface texture 4217, and the total area of ​​the third surface texture 4217 accounts for 10% to 20% of the area of ​​the third raceway 4211. It is understood that if the total area of ​​the third surface texture 4217 is too small, for example less than 10%, the effect of storing abrasive particles and lubricant is poor; while if the proportion is too large, for example greater than 20%, it can easily lead to accelerated wear. Therefore, a total area ratio of 10% to 20% for the third surface texture 4217 enables the third raceway 4211 to have good anti-friction capability and lubricant storage capability, solving the white layer problem of the third raceway 4211.

[0087] In one embodiment of the harmonic reducer of the present invention, the fourth raceway 4221 is provided with a fourth surface texture 4223, which can reduce the contact area between the second rolling element 470 and the fourth raceway 4221, suppress the abrasive particles from accelerating raceway wear, and thus reduce the appearance of a white layer on the fourth raceway 4221. The specific principle of this embodiment can be understood with reference to the third raceway 4211, and to avoid repetition, it will not be specifically limited here.

[0088] Reference Figure 21 and Figure 22 As shown, in this embodiment of the invention, the external toothed portion 111 includes circumferentially arranged protruding teeth 114 surrounding the cylindrical portion 110, in the direction from the external toothed portion 111 to the flange portion 130, i.e. Figure 22 From right to left, the tooth 114 includes a third modified section 1141, a middle section 1142, and a third modified section 1143 connected in sequence. The tooth height of the third modified section 1141 and the tooth height of the third modified section 1143 gradually decrease in the direction away from the middle section 1142. For example, the tooth tip of the third modified section 1141 and the third modified section 1143 can be inclined in a straight line, or be an outwardly convex arc, an inwardly concave arc, etc.

[0089] Along the rotation axis O parallel to the wave generator 300, the tooth width of the protrusion 114 is Lf1, and the width of the third shaping section 1141 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 middle section 1142 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 third shaping segment 1143 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.

[0090] Understandably, because the flexible wheel 100, under the action of the wave generator 300, transforms the cylindrical portion 110 into an elliptical shape, resulting in an angle, the motion trajectory of the outer tooth portion 111 differs at different interfaces. The optimal state is found in the middle section 1142 of the convex tooth 114, where interference is less likely to occur. However, interference with the inner tooth portion 210 is more likely to occur at the two ends of the convex tooth 114 along the axial direction. Therefore, by designing the tooth height of the third modified section 1141 and the tooth height of the third modified section 1143 to gradually decrease in the direction away from the middle section 1142, the interference between the tooth tip of the third modified section 1141 and the tooth tip of the third modified section 1143 and the inner tooth portion 210 can be effectively reduced.

[0091] The widths of the third modified section 1141, the intermediate section 1142, and the third modified section 1143 affect the meshing effect between the external tooth portion 111 and the internal tooth portion 210. When Lf2 is less than 0.2*Lf1, meaning the width of the third modified section 1141 is small, it is prone to interference with the internal tooth portion 210. When Lf2 is greater than 0.4*Lf1, meaning the width of the third modified section 1141 is large, while the width of the convex tooth 114 remains unchanged, the width of the intermediate section 1142 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the external tooth portion 111 and the internal tooth portion 210, and a decrease in meshing stability. When Lf3 is less than 0.35*Lf1, meaning the width of the intermediate section 1142 is small, it also leads to a reduction in the effective meshing area between the external tooth portion 111 and the internal tooth portion 210, and a decrease in meshing stability. When Lf3 is greater than 0.45*Lf1, with the width of the protruding tooth 114 remaining constant, the widths of the third modified segment 1141 and the third modified segment 1143 need to be reduced accordingly, which easily leads to interference with the internal tooth portion 210 at the third modified segment 1141 and the third modified segment 1143. When Lf4 is less than 0.25*Lf1, that is, the width of the third modified segment 1143 is small, it is easy to interfere with the internal tooth portion 210. When Lf4 is greater than 0.45*Lf1, that is, the width of the third modified segment 1143 is large, with the width of the protruding tooth 114 remaining constant, the width of the middle segment 1142 needs to be shortened accordingly, resulting in a reduction in the effective meshing area of ​​the external tooth portion 111 and the internal tooth portion 210, and a decrease in the stability during meshing.

[0092] Therefore, the ratio of the width of the third modified section 1141 to the width of the tooth 114 is set between 0.2 and 0.35, the ratio of the width of the middle section 1142 to the width of the tooth 114 is between 0.35 and 0.45, and the ratio of the width of the third modified section 1143 to the width of the tooth 114 is between 0.25 and 0.4. This can ensure the meshing stability of the tooth 114 and the internal tooth 210, while also reducing the interference between the external tooth 111 and the internal tooth 210, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear 100.

[0093] Reference Figure 23As shown, in an embodiment of the present invention, the tooth tip of the third modified segment 1141 is constructed as a first inclined surface 11411, which is inclined in a direction away from the intermediate segment 1142 and towards the rotation axis O. The tooth tip of the third modified segment 1143 is constructed as a second inclined surface 11431, which is inclined in a direction away from the intermediate segment 1142 and towards the rotation axis O. The inclination angle of the second inclined surface 11431 is greater than that of the first inclined surface 11411. It should be noted that the inclination angle of the first inclined surface 11411 refers to the angle α1 between the first inclined surface 11411 and the rotation axis O, and the inclination angle of the second inclined surface 11431 refers to the angle β1 between the second inclined surface 11431 and the rotation axis O. It is understandable that when the wave generator 300 is embedded in the inner hole of the cylindrical part 110, the outer wall of the cylindrical part 110 will be tilted, forming an angle. Since the third modified section 1143 is closer to the flange part 130 than the third modified section 1141, the third modified section 1143 is more likely to interfere with the internal tooth part 210. Therefore, by setting the inclination angle of the second inclined surface 11431 to be greater than the inclination angle of the first inclined surface 11411, the interference between the third modified section 1143 and the internal tooth part 210 can be effectively reduced or avoided, and the contact area between the third modified section 1143 and the internal tooth part 210 can be increased to improve the stability during power transmission.

[0094] Continue to refer to Figure 23 As shown in the embodiment of the present invention, in order to further reduce the interference between the external tooth portion 111 and the internal tooth portion 210, a third inclined surface 1144 is provided between two adjacent third shaping sections 1141. The third inclined surface 1144 is inclined in a direction away from the middle section 1142 and towards the rotation axis O. A fourth inclined surface 1145 is provided between two adjacent third shaping sections 1143. The fourth inclined surface 1145 is inclined in a direction away from the middle section 1142 and towards the rotation axis O. The inclination angle of the third inclined surface 1144 can be the same as or different from the inclination angle of the first inclined surface 11411, and the inclination angle of the fourth inclined surface 1145 can be the same as or different from the inclination angle of the second inclined surface 11431. This can effectively reduce or avoid the interference between the tooth tip of the internal tooth portion 210 and the tooth root of the external tooth portion 111, thereby reducing the friction and wear of the tooth surface and extending the life of the flexible gear 100.

[0095] Continue to refer to Figure 23As shown, in the embodiment of the present invention, the inclination angle of the first inclined surface 11411 is α1, satisfying: 0.3°≤α1≤1°. For example, the value of α1 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 11411 is too small, it is difficult to reduce the interference between the internal tooth portion 210 and the external tooth portion 111. When α1 is greater than 1°, it is easy to reduce the effective area when the third modified section 1141 and the internal tooth portion 210 mesh, thereby resulting in poor meshing stability. The inclination angle of the third inclined surface 1144 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°, meaning the inclination angle of the third inclined plane 1144 is too small, it is difficult to reduce interference between the internal tooth 210 and the external tooth 111. When α2 is greater than 1°, it can easily lead to a decrease in the strength of the external tooth 111, and tearing can easily occur between adjacent protrusions 114. Therefore, by rationally designing the sizes of α1 and α2, interference between the internal tooth 210 and the external tooth 111 can be effectively reduced, improving the service life of the flexible gear 100, while ensuring that the external tooth 111 has appropriate strength and high reliability.

[0096] Continue to refer to Figure 23 As shown, in an embodiment of the present invention, the inclination angle of the second inclined surface 11431 is β1, satisfying: 0.3°≤β1≤1°. For example, the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When β1 is less than 0.3°, that is, the inclination angle of the second inclined surface 11431 is too small, it is difficult to reduce the interference between the internal tooth portion 210 and the external tooth portion 111. When β1 is greater than 1°, it is easy to reduce the effective area when the third modified section 1143 and the internal tooth portion 210 mesh, thereby resulting in poor meshing stability. The inclination angle of the fourth inclined surface 1145 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°, meaning the inclination angle of the fourth inclined surface 1145 is too small, it is difficult to reduce interference between the internal tooth portion 210 and the external tooth portion 111. When β2 is greater than 1°, it can easily lead to a decrease in the strength of the external tooth portion 111, and tearing can easily occur between adjacent protrusions 114. Therefore, by rationally designing the sizes of β1 and β2, interference between the internal tooth portion 210 and the external tooth portion 111 can be effectively reduced, improving the service life of the flexible gear 100, while ensuring that the external tooth portion 111 has appropriate strength and high reliability.

[0097] Wherein, β1≥α1. It is understandable that, since the third modified section 1143 is closer to the flange portion 130 than the third modified section 1141, the third modified section 1143 is more likely to interfere with the internal gear portion 210. Therefore, by setting the inclination angle of the second inclined surface 11431 to be greater than the inclination angle of the first inclined surface 11411, the interference between the third modified section 1143 and the internal gear portion 210 can be effectively reduced or avoided, and the contact area between the third modified section 1143 and the internal gear portion 210 can be increased to improve the stability during power transmission.

[0098] Reference Figure 21 As shown in the embodiment of the present invention, the minimum distance between the end wall of the cylindrical portion 110 away from the flange portion 130 and the flange portion 130 is Lf, and the maximum length of the internal gear portion 210 along the axis of rotation is Lc, satisfying: 0.5*Lf≤Lc≤0.6*Lf, where the value of Lc can be 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, or 0.6*Lf. When Lc is less than 0.5*Lf, that is, the maximum length of the internal gear portion 210 is short, the contact area between the tooth surfaces of the internal gear portion 210 and the external gear portion 111 is reduced, the contact stress is increased, and the load-bearing capacity of the harmonic reducer is reduced. When Lc is greater than 0.6*Lf, that is, the maximum length of the internal gear portion 210 is large, the space occupied is too large, the strength margin is too large, which is not conducive to the miniaturization design of the harmonic reducer. Therefore, by rationally designing the maximum lengths Lc and Lf of the internal gear section 210, the contact area between the tooth surfaces of the internal gear section 210 and the external gear section 111 can be effectively increased, the contact stress can be reduced, the load-bearing capacity of the harmonic reducer can be improved, and the miniaturization design of the harmonic reducer can be facilitated.

[0099] Continue to refer to Figure 21As shown, in an embodiment of the present invention, the minimum distance between the end wall of the cylindrical portion 110 away from the flange portion 130 and the flange portion 130 is Lf. Along the direction parallel to the rotation axis O of the wave generator 300, the tooth width of the protruding tooth 114 is Lf1, satisfying: 0.45*Lf≤Lf1≤0.55*Lf. For example, the value of Lf1 can be 0.45*Lf, 0.46*Lf, 0.48*Lf, 0.5*Lf, 0.51*Lf, or 0.55*Lf. When Lf1 is less than 0.45*Lf, that is, the tooth width of the protruding tooth 114 is small, the contact area between the inner tooth portion 210 and the outer tooth portion 111 decreases, the contact stress increases, and the load-bearing capacity of the harmonic reducer decreases. When Lf1 is greater than 0.6*Lf, the tooth width of the convex tooth 114 is relatively large, occupying more space, which is not conducive to the flexible deformation of the cylinder 110, resulting in a decrease in the toughness of the flexure 100. Therefore, by rationally designing the ratio of Lf1 to Lf, the contact area between the tooth surfaces of the internal tooth 210 and the external tooth 111 can be increased, the contact stress can be reduced, the load-bearing capacity of the harmonic reducer can be improved, and at the same time, the flexure 100 can be ensured to have appropriate toughness.

[0100] Reference Figure 21 As shown, in the embodiment of the present invention, the tooth width Lf1 of the convex tooth 114 is less than the maximum length Lc of the internal tooth portion 210. It is understood that the flexure 100 experiences axial movement during operation, and due to machining errors, if the tooth width Lf1 of the convex tooth 114 is greater than the maximum length Lc of the internal tooth portion 210, a portion of the convex tooth 114 may not be in a meshing state, affecting the stability of the meshing. Since the harmonic reducer primarily checks the stability of the flexure 100, designing the tooth width Lf1 of the convex tooth 114 to be less than the maximum length Lc of the internal tooth portion 210 can improve the stability and reliability of the flexure 100's meshing.

[0101] Table 1: Comparison of tooth surface contact area under different schemes

[0102] For example, referring to Table 1 above, Scheme 1 is a scheme in the related technology, where Lc=0.42*Lf, Lf1=0.36*Lf, and the tooth height of the protruding tooth 114 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 protruding tooth 114 remains unchanged, i.e., no tooth profile modification is used; Scheme 3 is where Lc=0.55*Lf, Lf1=0.5*Lf, and the protruding tooth 114 has a modification scheme with a third modification segment 1141 and a third modification segment 1143. From Table 1 above, it can be seen that designing Lc=0.55*Lf and Lf1=0.5*Lf can increase the tooth surface contact area by 18.3%, and adding a modification scheme on this basis increases the improvement by 32.6% compared to Scheme 1. The larger the tooth surface contact area, the smaller the contact stress, and the greater the load-bearing capacity of the harmonic reducer.

[0103] An embodiment of the present invention discloses an industrial robot, including a motor and a harmonic reducer as described in the above embodiments. It is understood that the motor can be a servo motor, and the servo motor drives the harmonic reducer 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.

[0104] The industrial robot of this embodiment adopts the harmonic reducer described in the above embodiment. The harmonic reducer is equipped with a bearing device 400 for convenient assembly with the rigid wheel 200 and the flexible wheel 100. The bearing device 400 includes an inner bearing ring 410, a first outer bearing ring 421, a second outer bearing ring 422, a plurality of first rolling elements 460, and a plurality of second rolling elements 470. The inner bearing ring 410 is fixedly connected to the rigid wheel 200 and has a first raceway 411 and a third raceway 4211 at its two ends opposite to each other along the rotation axis O. The first outer bearing ring 421, the second outer bearing ring 422, and the flange portion 130 are fixedly connected. The first outer bearing ring 421 has a third raceway 4211 opposite to the first raceway 411. 11. The second outer bearing ring 422 is provided with a fourth raceway 4221 opposite to the third raceway 4211. Multiple first rolling elements 460 are installed in the first annular space formed between the first raceway 411 and the third raceway 4211, and multiple second rolling elements 470 are installed in the second annular space formed between the third raceway 4211 and the fourth raceway 4221. The raceways in the first annular space and the raceways in the second annular space are both complete raceways. The structure of setting two sets of complete raceways and two sets of rolling elements can effectively improve the load-bearing capacity of the harmonic reducer. While maintaining the compactness of the overall structure, it can improve the assembly efficiency between the bearing device 400, the rigid wheel 200, and the flexible wheel 100, and facilitate production scheduling.

[0105] The industrial robot of this invention adopts all the technical solutions of the harmonic reducer 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.

[0106] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention 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 the present invention.

Claims

1. A harmonic reducer characterized by, The application relates to a wave generator, a rigid wheel and a flexible wheel. The rigid wheel is provided with an inner tooth part. The flexible wheel comprises a barrel part and a flange part, and the barrel part is provided with an outer tooth part matched with the inner tooth part. The wave generator is coaxially installed in an inner hole of the flexible wheel. A bearing device is used for supporting the rigid wheel and the flexible wheel to enable the rigid wheel and the flexible wheel to relatively rotate, and the bearing device comprises an inner bearing ring, a first outer bearing ring, a second outer bearing ring, a plurality of first rolling bodies and a plurality of second rolling bodies.

2. The harmonic reducer of claim 1, wherein: The inner bearing ring is fixedly connected with the rigid wheel, and the inner bearing ring is provided with a first raceway and a second raceway at two ends away from the rotation axis of the wave generator.

3. The harmonic reducer of claim 1, wherein: The first raceway and the second raceway are annular and are arranged at intervals.

4. The harmonic reducer of claim 1, wherein: The first outer bearing ring, the second outer bearing ring and the flange part are fixedly connected, the first outer bearing ring is provided with a third raceway located outside the first raceway and opposite to the first raceway, and the second outer bearing ring is provided with a fourth raceway located outside the second raceway and opposite to the second raceway.

5. The harmonic reducer of claim 1, wherein: A plurality of the first rolling bodies are installed in a first annular space formed between the first raceway and the third raceway, and a plurality of the second rolling bodies are installed in a second annular space formed between the second raceway and the fourth raceway.

6. The harmonic reducer of claim 1, wherein: The inner hole diameter of the flexible wheel is Df, the maximum cross-sectional diameter of the first rolling body is Db1, and 0.07*Df<=Db1<=0.13*Df is met.

7. The harmonic reducer of claim 6, wherein: In the direction perpendicular to the rotation axis, the diameter of a circle with the centers of the plurality of first rolling bodies is Db2, and 1.3*Df<=Db2<=1.7*Df is met. The minimum distance between the end wall of the barrel part away from the flange part and the flange part is Lf, the maximum distance between the center of the first rolling body and the center of the second rolling body in the direction parallel to the rotation axis is L1, and 0.2*Lf<=L1<=0.28*Lf is met. The minimum distance between the end wall of the barrel part away from the flange part and the flange part is Lf, the first outer bearing ring is provided with a first end face abutting against the flange part, the maximum distance between the first end face and the center of the first rolling body is L2, and 0.24*Lf<=L2<=0.34*Lf is met. In the cross section passing through the rotation axis, the outer contour line of the first raceway is a first curve, the first curve comprises a first circular arc segment and a first modified segment, and the first modified segment is a non-circular arc. The radius of the first circular arc segment is Ri, the maximum cross-sectional diameter of the first rolling body 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 to the direction of the second rolling body, the Y axis is perpendicular to the X axis and points to the direction of the rotation axis, and the first curve meets the equation: When 0<=theta<=betai, rhoi=Ri+ki*Ri*[sin(90*theta / betai)-1]; When theta>betai, rhoi=Ri; Wherein, Ri = (0.505-0.515)*Db1, ki = 0.002-0.004, βi = 20°-30°.

8. The harmonic reducer of claim 1, 6 or 7, wherein: In a cross section passing through the rotation axis, the outer profile line of the third raceway is a second curve, and the second curve comprises a second circular arc segment and a second modified segment, and the second modified segment is a non-circular arc.

9. The harmonic reducer of claim 8, wherein: The radius of the second circular arc segment is Ro, the maximum cross-sectional diameter of the first rolling body 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 away from the second rolling body, and the Y axis is perpendicular to the X axis and points away from the rotation axis, and the second curve satisfies the equation: ρo = Ro + ko * Ro * [sin (90° * θ / βo) - 1], when 0° ≤ θ ≤ βo; ρo = Ro, when θ > βo; Wherein, Ro = (0.505-0.515)*Db1, ko = 0.002-0.004, βo = 20°-30°.

10. The harmonic reducer of claim 1, wherein: The first outer bearing ring is provided with a first step on the side facing the second outer bearing ring, and the second outer bearing ring is positioned and connected to the first step; the first outer bearing ring and the second outer bearing ring are connected by a first fastener; and / or, The rigid wheel is connected to the inner bearing ring on the side close to the second raceway, and the rigid wheel is provided with a second step on the side facing the inner bearing ring, and the inner bearing ring is positioned and connected to the second step; the rigid wheel and the inner bearing ring are connected by a second fastener.

11. The harmonic reducer of claim 1, wherein: A first oil storage space is formed between the bearing device and the flexible wheel, a second oil storage space is formed between the outer bearing ring and the inner bearing ring, the outer bearing ring and the inner bearing ring are provided with a first gap on the side of the second oil storage space close to the first oil storage space, and the outer bearing ring and the rigid wheel are provided with a second gap on the side of the second oil storage space away from the first oil storage space; The harmonic reducer further comprises a first oil seal and a second oil seal, the first oil seal is installed in the first gap and is used to block the exchange of lubricants in the first oil storage space and the second oil storage space, and the second oil seal is installed in the second gap and is used to block the outward overflow of the lubricant in the second oil storage space.

12. The harmonic reducer of claim 11, wherein: The inner wall of the first outer bearing ring is provided with a protruding portion extending towards the rotation axis, the inner bearing ring is provided with a stepped portion spaced from the protruding portion, and the first gap is formed between the protruding portion and the stepped portion; the first oil seal comprises a mounting ring and a first lip, the mounting ring is fixedly connected to the protruding portion, and the first lip is connected to the mounting ring and extends in the first gap to seal the first gap.

13. The harmonic reducer of claim 12, wherein: The first oil seal further comprises a second lip, the mounting ring comprises a first ring body and a second ring body, the first ring body is clamped to the end of the protruding portion at one end thereof facing the rotation axis, the second ring body is connected to the first ring body and extends towards the rotation axis, the second ring body is spaced apart from the inner bearing ring, and the second lip is connected to the second ring body and extends towards the inner bearing ring to seal the gap between the second ring body and the inner bearing ring.

14. The harmonic reducer of claim 13, wherein: The first ring body is provided with a stop shoulder located on the side wall of the protruding portion at the side thereof facing the inner bearing ring to limit the first oil seal from being pulled out in a direction away from the inner bearing ring.

15. Industrial robot, characterized in that: A harmonic reducer comprising any one of claims 1 to 14.

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