Harmonic speed reducer and industrial robot

Abstract

The utility model discloses a harmonic wave speed reducer and industrial robot relates to speed reducer technical field, wherein harmonic wave speed reducer includes flexible gear, rigid gear, wave generator and bearing device, the bearing device includes inner bearing ring, first outer bearing ring, second outer bearing ring, a plurality of first rolling body and second rolling body, 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 utility model relates to the technical field of reducers, in particular to a harmonic reducer and an industrial robot. Background Art

[0002] In the related art, harmonic reducers generally use single-row crossed roller bearings as support bearings. To facilitate the filling of rollers during bearing assembly, a roller filling port needs to be set on the inner or 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-bearing capacity of the support bearing, making it impossible for the harmonic reducer to meet the load-bearing capacity and vibration noise requirements while maintaining the compactness of the overall structure. Utility Model Content

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

[0004] The utility model also provides an industrial robot having the harmonic reducer.

[0005] According to the first embodiment of the utility model, the harmonic reducer comprises: a rigid wheel, provided with an inner tooth portion; a flexible wheel, comprising a cylinder portion and a flange portion, wherein the cylinder portion is provided with an outer tooth portion matching the inner tooth portion; a wave generator, coaxially mounted on the inner hole of the flexible wheel; A bearing device is used to support the rigid wheel and the flexible wheel so that they can rotate relative to each other, and the bearing device includes 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 to the rigid wheel, and the inner bearing ring is provided with a first raceway and a second raceway at two ends opposite to each other along the rotation axis of the wave generator, respectively, and the first raceway and the second raceway are annular and arranged at intervals; 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 on the outside of the first raceway and opposite to the first raceway, and the second outer bearing ring is provided with a fourth raceway located on the outside of 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] The harmonic reducer according to the embodiment of the utility model has at least the following beneficial effects:

[0007] A bearing device is provided for convenient assembly with a rigid wheel and a 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 elements and a plurality of second rolling elements, the inner bearing ring is fixedly connected to the rigid wheel and is respectively provided with a first raceway and a second raceway at two ends opposite to each other along the rotation axis, 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 opposite to the first raceway, the second outer bearing ring is provided with a fourth raceway opposite to the second raceway, a plurality of first rolling elements are installed in a first annular space formed between the first raceway and the third raceway, a plurality of second rolling elements 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 both complete raceways, and the structure of providing two sets of complete raceways and two sets of rolling elements can effectively improve the load-bearing capacity of the harmonic reducer, and while maintaining the compactness of the overall structure, improve the assembly efficiency between the bearing device and the rigid wheel and the flexible wheel, and facilitate production scheduling.

[0008] According to some embodiments of the present invention, the inner hole diameter of the flexible wheel is Df, and the maximum cross-sectional diameter of the first rolling element is Db1, which satisfies: 0.07*Df≤Db1≤0.13*Df.

[0009] According to some embodiments of the present invention, the inner hole diameter of the flexible wheel is Df, and in a direction perpendicular to the rotation axis, the diameter of the circle where the centers of the plurality of first rolling elements are located is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df.

[0010] According to some embodiments of the present invention, the minimum distance between the end wall of the barrel portion facing away from the flange portion and the flange portion is Lf, and in a direction parallel to the rotation axis, the maximum distance between the center of the first rolling body and the center of the second rolling body is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf.

[0011] According to some embodiments of the utility model, the minimum distance between the end wall of the cylinder portion facing away from the flange portion and the flange portion is Lf, the first outer bearing ring is provided with a first end face, the first end face abuts against the flange portion, and the maximum distance between the first end face and the center of the first rolling element is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

[0012] According to some embodiments of the present invention, in a cross section passing through the rotation axis, the outer contour line of the first raceway is a first curve, the first curve includes a first circular arc segment and a first modified segment, and the first modified segment is a non-circular arc.

[0013] 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 body 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 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 satisfies the equation:

[0014] ρi = Ri+ ki *Ri*[sin(90°*θ / βi)-1], when 0°≤θ≤βi;

[0015] ρi = Ri, when θ>βi;

[0016] Among them, Ri = (0.505-0.515)*Db1, ki = 0.002-0.004, βi=20°-30°.

[0017] According to some embodiments of the present invention, in a cross section passing through the rotation axis, the outer contour line of the third raceway is a second curve, the second curve includes a second circular arc segment and a second modified segment, and the second modified segment is a non-circular arc.

[0018] 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 body 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 body, the Y-axis is perpendicular to the X-axis and points away from the rotation axis, and the second curve satisfies the equation:

[0019] ρo = Ro+ko *Ro*[sin(90°*θ / βo)-1], when 0°≤θ≤βo;

[0020] ρo = Ro, when θ>βo;

[0021] Among them, Ro = (0.505-0.515)*Db1, ko=0.002-0.004, βo=20°-30°.

[0022] According to some embodiments of the utility model, a first step is provided on a side of the first outer bearing ring 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 a side of the inner bearing ring close to the second raceway, a second step is provided on a side of the rigid wheel 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.

[0023] According to some embodiments of the utility model, 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 also includes a first oil seal and a second oil seal, the first oil seal is installed in the first gap and is used to prevent the lubricant in the first oil storage space from exchanging with the lubricant in the second oil storage space, and the second oil seal is installed in the second gap and is used to prevent the lubricant in the second oil storage space from overflowing outward.

[0024] According to some embodiments of the utility model, the inner wall of the first outer bearing ring is provided with a protrusion extending toward the rotation axis, and the inner bearing ring is provided with a step portion spaced apart from the protrusion, and the first gap is formed between the protrusion and the step portion; the first oil seal includes 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.

[0025] According to some embodiments of the utility model, the first oil seal also includes a second lip, the mounting ring includes a first ring body and a second ring body, the first ring body is clamped to the end of the protrusion toward one end of the rotation axis, the second ring body is connected to the first ring body and extends toward the direction of 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 toward the inner bearing ring to seal the gap between the second ring body and the inner bearing ring.

[0026] According to some embodiments of the present invention, the first ring body is provided with a stop shoulder, and the stop shoulder is located on the side wall of the protrusion facing the inner bearing ring to limit the first oil seal from escaping in a direction away from the inner bearing ring.

[0027] The industrial robot according to the embodiment of the second aspect of the utility model includes the harmonic reducer described in the above embodiment.

[0028] The industrial robot according to the embodiment of the utility model has at least the following beneficial effects:

[0029] A harmonic reducer according to an embodiment of the first aspect is adopted. The harmonic reducer is provided with a bearing device that can be easily assembled with a rigid wheel and a flexible wheel. The bearing device includes 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 to the rigid wheel and is provided with a first raceway and a second raceway at two ends opposite to each other along the rotation axis, respectively. 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 opposite to the first raceway, and the second outer bearing ring is provided with a fourth raceway opposite to the second raceway. The plurality of first rolling elements are installed in a first annular space formed between the first raceway and the third raceway, and the plurality of second rolling elements are installed in a second annular space formed between the second raceway and the fourth raceway. Both the raceways in the first annular space and the raceways in the second annular space are complete raceways. The structure of providing 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, the assembly efficiency between the bearing device and the rigid wheel and the flexible wheel is improved, which is convenient for production scheduling.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0032] Figure 1 This is a structural cross-sectional view of a harmonic reducer according to an embodiment of the utility model;

[0033] Figure 2 for Figure 1 A partial cross-sectional view of the inner bearing ring, the outer bearing ring and the rigid wheel, wherein the rolling element is reduced in size to illustrate the matching relationship between the raceway and the rolling element;

[0034] Figure 3 for Figure 1 A partial enlarged view of the harmonic reducer shown;

[0035] Figure 4 for Figure 3 An enlarged view of A in the middle, showing a first oil seal of an embodiment;

[0036] Figure 5 for Figure 3 An enlarged view of A in the middle, showing a first oil seal of another embodiment;

[0037] Figure 6 for Figure 5 A cross-sectional view of a first oil seal of the illustrated embodiment;

[0038] Figure 7for Figure 1 The diagram showing the marking of various parameters of the harmonic reducer shown;

[0039] Figure 8 This is a front view of an inner bearing ring in a harmonic reducer according to an embodiment of the utility model;

[0040] Fig. 9 for Figure 8 The enlarged view of point B in the middle;

[0041] Fig.10 A cross-sectional view of an outer bearing ring in a harmonic reducer according to an embodiment of the utility model;

[0042] Fig.11 for Fig.10 Enlarged view of point C in the middle;

[0043] Fig.12 This is a relationship diagram between the ratio of Db1 and Df in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device, and the weight of the whole machine;

[0044] Fig.13 A diagram showing the relationship between the ratio of Db2 and Df in a harmonic reducer according to an embodiment of the utility model, the allowable torque of the bearing device, and the weight of the whole machine;

[0045] Fig.14 This is a relationship diagram between the ratio of L1 and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device, and the weight of the whole machine;

[0046] Fig.15 This is a relationship diagram between the ratio of L2 and Lf and the allowable torque and main body length of the bearing device in a harmonic reducer of an embodiment of the utility model;

[0047] Fig.16 A comparison diagram of the overturning moment rigidity before and after raceway modification in a harmonic reducer according to an embodiment of the utility model;

[0048] Fig.17 This is a front view of an inner bearing ring in a harmonic reducer according to another embodiment of the utility model;

[0049] Fig.18 for Fig.17 The enlarged view of point D in the middle;

[0050] Fig.19 A cross-sectional view of an outer bearing ring in a harmonic reducer according to another embodiment of the utility model;

[0051] Fig. 20 for Fig.19 Enlarged view of point E in the middle;

[0052] Fig.21It is a cross-sectional view of a flexible wheel and a rigid wheel in a harmonic reducer according to an embodiment of the utility model;

[0053] Fig. 22 for Fig.21 An enlarged cross-sectional view of the outer tooth portion shown;

[0054] Fig.23 This is a cross-sectional view of a partial structure of an external tooth portion in a harmonic reducer according to an embodiment of the utility model.

[0055] Figure Number:

[0056] Flexspline 100; cylinder 110; outer tooth 111; diaphragm 120; flange 130; convex tooth 114; third trimming section 1141; first slope 11411; middle section 1142; fourth trimming section 1143; second slope 11431; third slope 1144; fourth slope 1145;

[0057] The wheel 200; the inner tooth portion 210; the second step 220;

[0058] Wave generator 300; flexible bearing 310; cam 320;

[0059] Bearing device 400; inner bearing ring 410; first raceway 411; second raceway 412; boss 413; step 414; horizontal surface 4141; vertical surface 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 surface 4214; first step 4215; first end surface 4216; first three surface textures 4217; third recess 4218; second outer bearing ring 422; fourth raceway 4221; second end surface 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 trimming segment 482; second curve 490; second arc segment 491; second trimming segment 492;

[0060] A first oil storage space 500;

[0061] 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;

[0062] Second oil seal 700;

[0063] Axis of rotation O; center line of symmetry Q. DETAILED DESCRIPTION

[0064] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0065] In the description of the present invention, it should be understood that the descriptions involving orientation, such as the orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] In the description of the present utility model, "a plurality" means more than two. If there is a description of "first" or "second", it is only for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0067] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0068] As a kind of precision reducer, harmonic reducer has the advantages of compact structure, small size, light weight, large transmission ratio and load capacity, high transmission accuracy, etc. It is widely used in electronics, aerospace, robotics, automation and other industries. With the application market of harmonic reducer becoming more and more extensive, and the continuous exploration of new industries and use conditions, the market has continuously put forward higher performance requirements for harmonic reducer in terms of high torque, high overturning moment, high rigidity, low leakage and low vibration.

[0069] Reference Figure 1As shown, a harmonic reducer of an embodiment of the utility model comprises a flexible wheel 100, a rigid wheel 200 and a wave generator 300. The flexible wheel 100 is coaxially mounted in 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 comprises a barrel 110, a diaphragm 120 and a flange 130. The barrel 110 is located at one end of the flexible wheel 100 close to the rigid wheel 200, the diaphragm 120 is connected to one end of the barrel 110 away from the rigid wheel 200 and extends to the outside of the barrel 110, and the flange 130 is connected to the outer periphery of the diaphragm 120. The barrel 110 of the flexible wheel 100 is provided with a flexible outer tooth portion 111, and the rigid wheel 200 is provided with a rigid inner tooth portion 210. The outer tooth portion 111 cooperates with the inner tooth portion 210, and a meshing gap is formed between the outer tooth portion 111 and the inner tooth portion 210.

[0070] In the embodiment of the utility model, the wave generator 300 is connected to the inner hole of the flexible wheel 100 by interference fit, and the wave generator 300 is configured to make the outer tooth portion 111 mesh with the inner tooth portion 210 when rotating. After the wave generator 300 is installed in the inner hole of the flexible wheel 100, the flexible wheel 100 is forced to produce elastic deformation and become elliptical. During the operation of the harmonic reducer, the wave generator 300 rotates at a high speed to drive the flexible wheel 100 to deform repeatedly, so that the outer tooth portion 111 of the flexible wheel 100 meshes with the inner tooth portion 210 of the rigid wheel 200, and the meshing position of the outer tooth portion 111 and the inner tooth portion 210 moves along the circumferential direction of the rotation axis O of the wave generator 300, thereby realizing the relative deceleration movement between the flexible wheel 100 and the rigid wheel 200. The wave generator 300 includes a flexible bearing 310 and a cam 320, and the flexible bearing 310 is sleeved on the outer side of the cam 320, and the cam 320 is provided with a mounting position for connecting a driving device such as a motor.

[0071] Reference Figure 1 and Figure 2 As shown, the harmonic reducer of one embodiment of the utility model further includes a bearing device 400, which is used to support the rigid wheel 200 and the flexible wheel 100, and enable the rigid wheel 200 and the flexible wheel 100 to achieve relative rotation. The bearing device 400 is arranged around the outer side of the cylinder 110, and the bearing device 400 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 arranged around the outer side of the inner bearing ring 410 and fixedly connected to the flange part 130, and the inner bearing ring 410 and the outer bearing ring 420 can achieve relative rotation.

[0072] In the harmonic reducer of the embodiment of the utility model, 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 by fasteners (such as screws, bolts, pins, etc.); or they can be fixed separately in pairs, that is, the flange portion 130 and the first outer bearing ring 421 are fixedly connected by a group of fasteners, and the first outer bearing ring 421 and the second outer bearing ring 422 are fixedly connected by another group of fasteners. In actual use, it is necessary to select according to the assembly requirements and load requirements of the harmonic reducer, which is not specifically limited here.

[0073] 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 opposite ends along the rotation axis O of the wave generator 300, respectively. The first raceway 411 and the third raceway 4211 are both annular and are arranged at intervals in the direction of the rotation axis O.

[0074] The first outer bearing ring 421 is provided with a third raceway 4211 located outside the first raceway 411 (i.e., on the side away from the third raceway 4211) and opposite to the first raceway 411, and the second outer bearing ring 422 is provided with a fourth raceway 4221 located outside the third raceway 4211 (i.e., on the side away from the first raceway 411) and opposite to the third raceway 4211, and 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 bodies 460 are installed in the first annular space, and a second annular space is formed between the third raceway 4211 and the fourth raceway 4221, and a plurality of second rolling bodies 470 are installed in the second annular space.

[0075] The embodiment of the utility model adopts two groups of rolling elements consisting of a plurality of first rolling elements 460 and a plurality of second rolling elements 470. Compared with the single-row cross roller bearing in the related art, the bearing device 400 can improve its load-bearing capacity. Moreover, the structure of the inner bearing ring 410, the first outer bearing ring 421 and the second outer bearing ring 422 is conducive to the assembly of the harmonic reducer and is easier to adapt to different loads. It is understandable that the first rolling element 460 can be a sphere, or a cylinder, cone or other column; the second rolling element 470 can be a sphere, or a cylinder, cone or other column, which is not specifically limited here. In addition, in the present embodiment, the first rolling element 460 and the second rolling element 470 can be made of metal materials such as steel.

[0076] When the first outer bearing ring 421 and the second outer bearing ring 422 of the embodiment of the utility model are assembled with the inner bearing ring 410, they can be close to each other in the direction of the rotation axis O, and multiple first rolling bodies 460 and multiple second rolling bodies 470, as well as accessories such as mounting frames, can be installed simultaneously, until the first outer bearing ring 421 and the second outer bearing ring 422 are abutted and fixed in the direction of the rotation axis O, thereby cooperating with the inner bearing ring 410 to form a stable bearing device 400. Moreover, the flexible wheel 100 and the rigid wheel 200 are respectively installed at both ends of the bearing device 400, so as to realize convenient installation with the bearing device 400. 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 up two sets of complete raceways and two sets of rolling bodies, the load-bearing capacity of the harmonic reducer can be effectively improved while maintaining the compactness of the overall structure. The two sets of accessories, the rigid wheel 200 and the flexible wheel 100, and the bearing device 400 can be produced separately and assembled later, which is convenient for production scheduling; and the assembly efficiency between the bearing device 400 and the rigid wheel 200 and the flexible wheel 100 is improved, thereby improving the production efficiency of the harmonic reducer.

[0077] Reference Figure 2 As shown, a first step 4215 is provided on the side of the first outer bearing ring 421 facing the second outer bearing ring 422, and the second outer bearing ring 422 is positioned and connected to the first step 4215, so that the first outer bearing ring 421 and the second outer bearing ring 422 are axially positioned and radially positioned, thereby improving assembly efficiency and assembly accuracy. The first outer bearing ring 421 is connected to the second outer bearing ring 422 by a plurality of first fasteners, and the plurality of first fasteners 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.

[0078] Reference Figure 2 As shown, the rigid wheel 200 is connected to the side of the inner bearing ring 410 close to the third raceway 4211, and the side of the rigid wheel 200 facing the inner bearing ring 410 is provided with a second step 220, and the inner bearing ring 410 is positioned and connected to the second step 220, so that the rigid wheel 200 and the inner bearing ring 410 are axially and radially positioned, thereby improving the assembly efficiency and assembly accuracy. The rigid wheel 200 is connected to the inner bearing ring 410 through a plurality of second fasteners, and the plurality of second fasteners are arranged at intervals around the rigid wheel 200. It can be understood that the second fasteners can be screws, bolts, pins, etc.

[0079] 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 the rigid wheel 200.

[0080] Reference Figure 2 and Figure 3 As shown, a first oil storage space 500 is formed between the bearing device 400 and the cylinder 110 and the diaphragm 120 of the flexible wheel 100, and the first oil storage space 500 is connected to the meshing gap. Figure 3 The dotted arrows are the flow direction of the lubricant: specifically, from the inner hole of the flexible wheel 100 to the meshing gap, and then to the first oil storage space 500. The lubricant lubricates the wave generator 300 at the inner hole of the flexible wheel 100, and the lubricant further acts on the gear pair between the flexible wheel 100 and the rigid wheel 200, and finally gathers in the first oil storage space 500. The lubricant in the first oil storage space 500 can continuously lubricate the gear pair.

[0081] A second oil storage space 430 is formed between the outer bearing ring 420 and the inner bearing ring 410, and the second oil storage space 430 is used to lubricate the raceway and rolling elements in the bearing device 400. In order to realize the assembly of the bearing device 400, there are gaps on both sides of the matching position of the outer bearing ring 420 and the inner bearing ring 410, including a first gap 440 provided between the outer bearing ring 420 and the inner bearing ring 410 on the side of the second oil storage space 430 close to the first oil storage space 500, and a second gap 450 provided 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.

[0082] The harmonic reducer of one embodiment of the utility model further includes a first oil seal 600 and a second oil seal 700. The first oil seal 600 is installed in the first gap 440, and is used to prevent the lubricant in the first oil storage space 500 from exchanging with the lubricant in the second oil storage space 430. The second oil seal 700 is installed in the second gap 450, and is used to prevent the 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 keeps in contact with the outer peripheral wall of the rigid wheel 200, and the two have relative rotational motion when the harmonic reducer is working, forming a radial contact seal. The second oil seal 700 generally adopts a conventional skeleton oil seal.

[0083] Since foreign matter such as iron powder and abrasive particles are easily generated when the outer tooth portion 111 and the inner tooth portion 210 are meshing, the iron powder and abrasive particles will be mixed into the lubricant to contaminate the lubricant. The contaminated lubricant has little effect on the flexible bearing 310, the inner tooth portion 210 and the outer tooth portion 111, but has a greater impact on the bearing device 400, which is subject to greater contact stress; therefore, providing the first oil seal 600 can inhibit the lubricant containing iron powder and abrasive particles in the first oil storage space 500 from entering the second oil storage space 430, effectively preventing the bearing device 400 from being abnormally damaged and thus causing premature damage, thereby increasing the service life of the harmonic reducer.

[0084] Under the joint action of the first oil seal 600 and the second oil seal 700, the second oil storage space 430 is formed into a sealed cavity, which is isolated from the first oil storage space 500. Therefore, different lubricants can be used in the first oil storage space 500 and the second oil storage space 430. 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 further improving the overall performance of the harmonic reducer.

[0085] 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 rigid wheel 200, thereby improving the sealing performance of the harmonic reducer.

[0086] Reference Figure 2 and Figure 3 As shown, it can be understood that the end face of the second outer bearing ring 422 facing away from the first outer bearing ring 421 is the second end face 4222, and 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, which is simpler and more convenient to assemble.

[0087] Reference Figure 2 As shown, the inner bearing ring 410 forms a boss 413 between the first raceway 411 and the third raceway 4211, and 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, and 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 element and the raceway.

[0088] In order to prevent the lubricant in 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. Figure 2 and Figure 3As shown, the inner wall of the first outer bearing ring 421 extends toward the rotation axis O and is provided with a protrusion 4212, the center of the protrusion 4212 is formed as a through hole, the inner bearing ring 410 is provided with a step portion 414 spaced from the protrusion 4212, and the first gap 440 is formed between the protrusion 4212 and the step portion 414. A first gap is formed between the inner hole surface 4213 of the protrusion 4212 and the horizontal surface 4141 of the step portion 414, and a second gap is formed between the right end surface 4214 of the protrusion 4212 and the vertical surface 4142 of the step portion 414. The first gap and the second gap are arranged 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 the first gap and the second gap at the same time to achieve double sealing. In another embodiment, the first oil seal 600 can be configured to seal the second gap, and the first gap acts as a labyrinth seal to prevent lubricant from entering the second gap. When the harmonic reducer is working, the lip of the first oil seal 600 and the inner bearing ring 410 are in contact, and there is relative rotation between the two, forming an axial contact seal.

[0089] Reference Figure 4 As shown, in one embodiment of the utility model, 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-connected in the through hole of the protrusion 4212, or installed in the through hole by bonding, screwing, etc. As another embodiment, the mounting ring 610 can also be fixedly connected to the right end surface 4214 (the end away from the flange part 130) or the left end wall (the end facing the flange part 130) of the protrusion 4212. The first lip 620 is connected to the mounting ring 610, and 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.

[0090] In order to improve the stability of the first oil seal 600, the mounting ring 610 is integrally manufactured with a metal material, for example, manufactured by a stamping process, so that the overall structure of the first oil seal 600 is more stable. The first lip 620 is configured as a sealing ring wrapped around at least a portion of the outer wall of the mounting ring 610, and is configured to seal the connection between the first section gap and the second section gap in the first gap 440. The sealing ring is integrally manufactured with a rubber material and then installed on the mounting ring 610, or is integrally injection molded with the mounting ring 610, which can achieve a better sealing effect.

[0091] Reference Figure 5 and Figure 6As shown, in another embodiment of the utility model, the first oil seal 600 includes a first lip 620 and a second lip 630, the mounting ring 610 includes a first ring body 611 and a second ring body 612, the first ring body 611 is clamped to the end of the protrusion 4212 toward one end of 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.

[0092] The second ring body 612 is connected to the first ring body 611 and extends toward the direction of the rotation axis O. The second ring body 612 and the left end surface of the inner bearing ring 410 are spaced to form a third gap 640 connected to the first gap 440. The third gap 640 and the first section of the gap of the first gap 440 are arranged at an angle to each other, so the third gap 640 and the first gap 440 form a labyrinth seal. The second lip 630 is fixedly connected to the second ring body 612 and extends to the inner bearing ring 410, thereby sealing the third gap 640 between the second ring body 612 and the inner bearing ring 410, further inhibiting the lubricant from entering the second oil storage space 430. In this embodiment, two-stage sealing is achieved through the first lip 620 and the second lip 630, and a labyrinth seal formed by the first gap 440 and the third gap 640 is formed, so that the lubricant in the first oil storage space 500 and the lubricant in the second oil storage space 430 can be better blocked from exchanging, thereby protecting the life of the bearing device 400.

[0093] 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, and the shoulder 613 is located on the side wall of the protrusion 4212 facing the inner bearing ring 410 (i.e., the right end face 4214), and the shoulder 613 can limit the first oil seal 600 from escaping in the direction away from the inner bearing ring 410, thereby improving the installation stability of the first oil seal 600.

[0094] In order to improve the stability of the first oil seal 600, the first ring body 611, the second ring body 612 and the shoulder 613 are integrally manufactured with metal materials, for example, by a stamping process or a folding process, so that the overall structure of the first oil seal 600 is more stable. The first lip 620 and the second lip 630 are configured as sealing rings wrapped around at least a portion of the outer wall of the mounting ring 610. The sealing rings are integrally manufactured with rubber materials and then mounted on the mounting ring 610, or are integrally injection molded with the mounting ring 610. Therefore, the sealing rings can play a good sealing effect on the first gap 440 and the third gap 640.

[0095] Reference Figure 7As 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, that is, the diameter of the maximum 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, and 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. The plurality of first rolling elements 460 are arranged at intervals along the circumference of the rotation axis O, and the diameter of the circle where the centers of the plurality of first rolling elements 460 are located in the direction perpendicular to the rotation axis O is defined as Db2.

[0096] 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 flexible spline 100; the larger the Lf, the greater the flexibility of the flexible spline 100; conversely, the smaller the Lf, the greater the rigidity of the flexible spline 100.

[0097] The plurality of second rolling bodies 470 are arranged at intervals along the axial direction of the rotation axis O. The maximum distance between the center of the first rolling body 460 and the center of the second rolling body 470 is defined as L1 between the two first rolling bodies 460 and the second rolling body 470 parallel to the rotation axis O. L1 is related to the span of the bearing device 400; the larger L1 is, the larger the span is, and the better the anti-overturning ability of the bearing device 400 is; conversely, the smaller L1 is, the smaller the span is, and the worse the anti-overturning ability of the bearing device 400 is.

[0098] The first outer bearing ring 421 is provided with a first end surface 4216 , the first end surface 4216 is in contact with the flange portion 130 , and the maximum distance between the first end surface 4216 and the center of the first rolling element 460 is L2 .

[0099] 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. Fig.12 The figure is a relationship diagram between the ratio of Db1 and Df in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device 400, and the weight of the whole machine. It should be noted that the allowable torque is the maximum overturning torque that the bearing device 400 can withstand during normal use. Fig.12As shown in the figure, when Db1 / Df is less than 0.07, the weight of the whole machine of the harmonic reducer remains basically unchanged, but the allowable torque decreases rapidly and cannot meet the use requirements. When Db1 / Df is greater than 0.13, although the allowable torque continues to increase, the weight of the whole machine increases rapidly and cannot meet the use requirements. Therefore, by weighing the requirements of the whole machine weight and the allowable torque of the harmonic reducer, the maximum cross-sectional diameter Db1 of the first rolling element 460 is set to 0.07*Df to 0.13*Df, which can meet the requirements of the maximum overturning moment and the weight of the whole machine at the same time.

[0100] 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 where the centers of the multiple first rolling bodies 460 are located 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. Fig.13 The figure is a relationship diagram between the ratio of Db2 and Df in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device 400, and the weight of the whole machine. It should be noted that the allowable torque is the maximum overturning torque that the bearing device 400 can withstand during normal use. Fig.13 As shown in the figure, when Db2 / Df is less than 1.3, the weight of the whole machine of the harmonic reducer remains basically unchanged, but the allowable torque decreases rapidly and cannot meet the use requirements. When Db2 / Df is greater than 1.7, although the allowable torque continues to increase, the weight of the whole machine increases rapidly and cannot meet the use requirements. Therefore, by weighing the requirements of the whole machine weight and the allowable torque of the harmonic reducer, the diameter Db2 of the circle where the center of the first rolling element 460 is located is set to 1.3*Df to 1.7*Df, which can simultaneously meet the requirements of the maximum overturning moment and the weight of the whole machine.

[0101] Reference Figure 7 As shown, it can be understood that the maximum distance L1 between the center of the first rolling body 460 and the center of the second rolling body 470 parallel to the rotation axis 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. Fig.14 The figure is a relationship diagram between the ratio of L1 and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device 400, and the weight of the whole machine. It should be noted that the allowable torque is the maximum overturning torque that the bearing device 400 can withstand during normal use. Fig.14As shown in the figure, when L1 / Lf is less than 0.2, the weight of the whole machine of the harmonic reducer changes relatively slowly, but the allowable torque decreases rapidly and cannot meet the use requirements. When L1 / Lf is greater than 0.28, although the allowable torque continues to increase, the weight of the whole machine also increases rapidly and cannot meet the use requirements. Therefore, by weighing the requirements of the whole machine weight and the allowable torque of the harmonic reducer, the maximum distance L1 between the center of the first rolling body 460 and the center of the second rolling body 470 parallel to the rotation axis O is set at 0.2*Lf to 0.28*Lf, which can meet the requirements of the maximum overturning moment and the weight of the whole machine at the same time.

[0102] Reference Figure 7 As shown, it can be understood that the maximum distance between the first end face 4216 and the center of the first rolling body 460 is L2, satisfying: 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. Fig.15 The figure is a relationship diagram between the ratio of L2 and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the bearing device 400, and the main body length. It should be noted that the allowable torque is the maximum overturning torque that the bearing device 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 device 400 along the rotation axis O. Fig.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 and cannot meet the use requirements. When L2 / Lf is greater than 0.34, the allowable torque decreases significantly, and the main body length increases rapidly, which cannot meet the use requirements. Therefore, by weighing the requirements of the main body length and the allowable torque of the harmonic reducer, the maximum distance L2 between the first end face 4216 and the center of the first rolling element 460 is set to 0.2*Lf to 0.28*Lf, which can simultaneously meet the requirements of the maximum overturning moment and the main body length.

[0103] Reference Figure 8 and Fig. 9As shown, in the cross section passing through the rotation axis O, the outer contour line of the first raceway 411 is a first curve 480. Since the first raceway 411 is located outside the inner bearing ring 410 and the first raceway 411 is annular, the outer contour line formed by the first raceway 411 in the main view of the inner bearing ring 410 is the same as the outer contour line in the cross section passing through the rotation axis O. For the convenience of description, the embodiment of the utility model is introduced by taking the main view of the inner bearing ring 410 as an example. Compared with the arc-shaped raceway in the related art, the first raceway 411 of this embodiment is reshaped. Specifically, the first curve 480 includes a first arc segment 481 and a first reshaped segment 482, and the first reshaped segment 482 is a non-circular arc. By means of the modified first raceway 411, when subjected to a larger overturning moment, the contact area between the first rolling element 460 and the first raceway 411 is larger, which can reduce the contact stress between the first rolling element 460 and the first raceway 411, thereby improving the bearing capacity of the bearing device 400, such as the overall overturning moment and overturning moment rigidity.

[0104] Reference Fig. 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, and the X-axis is parallel to the rotation axis O and points to the direction of the second rolling body 470 (i.e. Fig. 9 The Y axis is perpendicular to the X axis and points to the direction of the rotation axis O (i.e. Fig. 9 ), the first curve 480 satisfies the equation:

[0105] ρi = Ri+ ki *Ri*[sin(90°*θ / βi)-1], when 0°≤θ≤βi;

[0106] ρi = Ri, when θ>βi;

[0107] Among them, 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°.

[0108] The embodiment of the utility model designs the first curve 480 so that when the first raceway 411 is subjected to a large overturning moment, there is multi-point contact between the first rolling element 460 and the first raceway 411, thereby increasing the contact position and contact area and reducing the contact stress, which is significantly better than the single-point contact between the first rolling element 460 and the first raceway 411 in the related art (before shaping).

[0109] For example, when the bearing device 400 is subjected to force, the first rolling element 460 and the first raceway 411 will deform. Before the modification, the first rolling element 460 and the first raceway 411 have a single point contact at a position of about 40°; however, after the modification, the first rolling element 460 and the first raceway 411 not only have contact at a position of about 40°, but also have contact between 10° and 20°.

[0110] Fig.16 This is a comparison diagram of the overturning moment rigidity of the first raceway 411 before and after the modification in a harmonic reducer of an embodiment of the utility model. Fig.16 As shown, after the first raceway 411 is modified, when the bearing device 400 is subjected to a large torque (such as Fig.16 As shown in the figure, when the angle of the overturning moment is greater than 600 N.m, the angle generated by the overturning moment becomes smaller; according to the overturning moment rigidity = overturning moment / angle generated by the overturning moment, when the overturning moment is constant, the smaller the angle generated by the overturning moment, the greater the overturning moment rigidity. Therefore, after the first raceway 411 of the embodiment of the utility model is modified by the above equation, the overturning moment rigidity is improved to varying degrees, even up to 20%.

[0111] It can be understood that in this embodiment, the first raceway 411 and the third raceway 4211 are symmetrical with respect to the symmetry center line Q of the first rolling body 460 and the second rolling body 470, the outer contour line of the third raceway 4211 is the third curve, and the third curve and the first curve 480 are symmetrical with respect to the symmetry center line Q of the first rolling body 460 and the second rolling body 470. Therefore, it can be understood by referring to the equation of the first curve 480. In order to avoid repetition, it will not be repeated here.

[0112] Reference Fig.10 and Fig.11 As shown, in the cross section passing through the rotation axis O, the outer contour line of the third raceway 4211 is a second curve 490, and the second curve 490 includes a second arc segment 491 and a second modified segment 492, and the second modified segment 492 is a non-circular arc. Compared with the arc-shaped raceway in the related art, the third raceway 4211 of this embodiment is modified. Through 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 bearing capacity of the overall overturning moment and overturning moment rigidity of the bearing device 400.

[0113] Reference Fig.11 As shown, the radius of the second arc segment 491 is Ro, and a coordinate system is established with the center of the second arc segment 491 as the origin, and the X-axis is parallel to the rotation axis O and points in a direction away from the second rolling element 470 (i.e. Fig.11The Y axis is perpendicular to the X axis and points away from the rotation axis O (i.e. Fig.11 In the upward direction), the second curve 490 satisfies the equation:

[0114] ρo = Ro+ko *Ro*[sin(90°*θ / βo)-1], when 0°≤θ≤βo;

[0115] ρo = Ro, when θ>βo;

[0116] Among them, 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°.

[0117] The embodiment of the utility model designs the second curve 490 so that when the third raceway 4211 is subjected to a large overturning moment, there is multi-point contact between the first rolling element 460 and the third raceway 4211, thereby increasing the contact position and contact area and reducing the contact stress, which is significantly better than the single-point contact between the first rolling element 460 and the third raceway 4211 in the related art (before shaping).

[0118] For example, when the bearing device 400 is subjected to force, the first rolling element 460 and the third raceway 4211 will deform. Before the modification, the first rolling element 460 and the third raceway 4211 have a single point contact at a position of about 40°; however, after the modification, the first rolling element 460 and the third raceway 4211 not only have contact at a position of about 40°, but also have contact between 10° and 20°.

[0119] Fig.16 This is a comparison diagram of the overturning moment rigidity of the third raceway 4211 before and after the modification in a harmonic reducer of an embodiment of the utility model. Fig.16 As shown, after the third raceway 4211 is modified, when the bearing device 400 is subjected to a large torque (such as Fig.16 As shown in the figure, when the angle of the overturning moment is greater than 600 N.m, the angle generated by the overturning moment becomes smaller; according to the overturning moment rigidity = overturning moment / angle generated by the overturning moment, when the overturning moment is constant, the smaller the angle generated by the overturning moment, the greater the overturning moment rigidity. Therefore, after the third raceway 4211 of the embodiment of the utility model is modified by the above equation, the overturning moment rigidity is improved to varying degrees, even up to 20%.

[0120] It can be understood that in this embodiment, the third raceway 4211 and the fourth raceway 4221 are symmetrical with respect to the symmetry center line Q of the first rolling body 460 and the second rolling body 470, and the outer contour line of the fourth raceway 4221 cooperating with the second rolling body 470 is the fourth curve. The fourth curve and the second curve 490 are symmetrical with respect to the symmetry center line Q of the first rolling body 460 and the second rolling body 470. Therefore, it can be understood by referring to the equation of the second curve 490. In order to avoid repetition, it will not be repeated here.

[0121] Reference Fig.17 and Fig.18 As shown, in a harmonic reducer of an embodiment of the utility model, the first raceway 411 is provided with a first surface texture 415, and the first surface texture 415 includes a plurality of first recesses 4151 arranged at intervals. The first surface texture 415 is provided on the first raceway 411. Due to the presence of the first recesses 4151, the contact area between the first rolling body 460 and the first raceway 411 can be reduced. The reduction of the contact area is conducive to reducing the generation of abrasive particles, and the generated abrasive particles can also be stored in the first recesses 4151, which inhibits the abrasive particles from entering the contact surface between the first raceway 411 and the first rolling body 460, thereby inhibiting the abrasive particles from aggravating the raceway wear, thereby reducing the appearance of the white layer of the first raceway 411. The first surface texture 415 can also store lubricant. When the first rolling body 460 squeezes the first raceway 411, it will cause a slight deformation of the first raceway 411, squeeze out the lubricant in the first recess 4151, play a role in supplementing lubrication, improve lubrication conditions, and reduce 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 of the machine.

[0122] Reference Fig.18 As shown, it can be understood that the first depression 4151 is hemispherical, and the depth of the first depression 4151 is 2μm to 10μm. It can be understood that if the depth of the first depression 4151 is too small, for example, less than 2μm, it is easy to be worn flat by the first rolling body 460, so that the ability to store lubricants and abrasive particles is reduced, and it cannot play a role in reducing friction loss during long-term use; and if the depth is too small, it is difficult to process. If the depth of the first depression 4151 is too large, for example, greater than 10μm, it is easy to cause the lubrication effect to deteriorate, and it is difficult to form a continuous oil film on the surface of the first raceway 411.

[0123] The port diameter of the first depression 4151 is 50 μm to 200 μm. When the port diameter of the first depression 4151 is less than 50 μm, the ability to store abrasive particles and lubricants is low; the port diameter of the first depression 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 depression 4151 is greater than 200 μm, that is, greater than the contact width between the first rolling element 460 and the first raceway 411, the first rolling element 460 does not run smoothly and causes increased wear.

[0124] 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 lubricants, and can improve the oil film bearing capacity.

[0125] Reference Fig.18 As shown, the first raceway 411 of the embodiment of the utility model 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 can be understood that when the total area of ​​the first surface texture 415 accounts for too small an area of ​​the first raceway 411, such as less than 10%, the effect of storing abrasive particles and lubricants is poor; and when the proportion is too large, such as greater than 20%, it is easy to cause aggravated wear. Therefore, the total area of ​​the first surface texture 415 accounts for 10% to 20%, which can enable the first raceway 411 to have good anti-friction ability and lubricant storage ability, and solve the white layer problem of the first raceway 411.

[0126] Reference Fig.17 and Fig.18 As shown, in a harmonic reducer of an embodiment of the utility model, 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, inhibit the abrasive particles from aggravating the raceway wear, and thus reduce the appearance of the white layer of the second raceway 412. The specific principle of this embodiment can be understood with reference to the first raceway 411, and in order to avoid repetition, it is not specifically defined here.

[0127] Reference Fig.19 and Fig. 20As shown, in a harmonic reducer of an embodiment of the utility model, the third raceway 4211 is provided with a third surface texture 4217, and the third surface texture 4217 includes a plurality of third recesses 4218 arranged at intervals. The third surface texture 4217 is provided on the third raceway 4211. Due to the presence of the third recesses 4218, the contact area between the first rolling body 460 and the third raceway 4211 can be reduced. The reduction in the contact area is conducive to reducing the generation of abrasive particles, and the generated abrasive particles can also be stored in the third recesses 4218, which inhibits the abrasive particles from entering the contact surface between the third raceway 4211 and the first rolling body 460, thereby inhibiting the abrasive particles from aggravating the raceway wear, thereby reducing the appearance of the white layer of the third raceway 4211. The third surface texture 4217 can also store lubricant. When the first rolling body 460 squeezes the third raceway 4211, it will cause a slight deformation of the third raceway 4211, squeezing the lubricant in the third recess 4218, thereby supplementing lubrication, improving lubrication conditions, and 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 of the machine.

[0128] Reference Fig. 20 As shown, it is understood that the third depression 4218 is hemispherical, and the depth of the third depression 4218 is 2 μm to 10 μm. It is understood that if the depth of the third depression 4218 is too small, for example, less than 2 μm, it is easy to be worn flat by the first rolling body 460, so that the ability to store lubricants and abrasive particles is reduced, and it cannot play a role in reducing friction loss during long-term use; and if the depth is too small, it is difficult to process. If the depth of the third depression 4218 is too large, for example, greater than 10 μm, it is easy to cause the lubrication effect to deteriorate, and it is difficult to form a continuous oil film on the surface of the third raceway 4211.

[0129] The port diameter of the third recess 4218 is 50 μm to 200 μm. When the port diameter of the third recess 4218 is less than 50 μm, the ability to store abrasive particles and lubricants 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, that is, greater than the contact width between the first rolling element 460 and the third raceway 4211, the first rolling element 460 does not run smoothly and causes increased wear.

[0130] Therefore, designing the third recess 4218 according to the above parameters can enable the third recess 4218 to have a good ability to store abrasive particles and lubricants, and can improve the oil film bearing capacity.

[0131] Reference Fig. 20As shown, the third raceway 4211 of the embodiment of the utility model 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 can be understood that when the total area of ​​the third surface texture 4217 accounts for too small an area of ​​the third raceway 4211, such as less than 10%, the effect of storing abrasive particles and lubricants is poor; and when the proportion is too large, such as greater than 20%, it is easy to cause aggravated wear. Therefore, the total area of ​​the third surface texture 4217 accounts for 10% to 20%, which can enable the third raceway 4211 to have good anti-friction ability and lubricant storage ability, and solve the white layer problem of the third raceway 4211.

[0132] In a harmonic reducer of an embodiment of the utility model, 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, inhibit the abrasive particles from aggravating the 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 is not specifically defined here to avoid repetition.

[0133] Reference Fig.21 and Fig. 22 As shown, in the embodiment of the present invention, the outer tooth portion 111 includes protruding teeth 114 arranged around the circumference of the barrel portion 110, and the direction from the outer tooth portion 111 to the flange portion 130, that is, Fig. 22 From right to left, the convex tooth 114 includes a third trimming segment 1141, a middle segment 1142 and a third trimming segment 1143 connected in sequence, and the tooth height of the third trimming segment 1141 and the tooth height of the third trimming segment 1143 are gradually reduced in the direction away from the middle segment 1142. For example, the tooth tops of the third trimming segment 1141 and the third trimming segment 1143 can be inclined in a straight line direction, or be an outward convex arc, an inward concave arc, etc.

[0134] Along the direction parallel to the rotation axis O of the wave generator 300, the tooth width of the convex tooth 114 is Lf1, and the width of the third modified section 1141 is Lf2, which satisfies: 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, 0.35*Lf1. The width of the middle section 1142 is Lf3, which satisfies: 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, 0.45*Lf1. The width of the third trimming section 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.

[0135] It can be understood that, since the flexible wheel 100 is transformed into an elliptical shape by the action of the wave generator 300, there is an opening angle, and the motion trajectories of the outer tooth portion 111 at different interfaces are different. The state of the middle part of the convex tooth 114, that is, the middle section 1142 is optimal and is not prone to interference, while the two ends of the convex tooth 114 along the axial direction are prone to interference with the inner tooth portion 210. To this end, by designing the tooth height of the third trimming section 1141 and the tooth height of the third trimming section 1143 to gradually decrease in the direction away from the middle section 1142, the interference between the tooth top of the third trimming section 1141 and the tooth top of the third trimming section 1143 and the inner tooth portion 210 can be effectively reduced.

[0136] The widths of the third trimming section 1141, the middle section 1142 and the third trimming section 1143 will affect the meshing effect between the outer tooth portion 111 and the inner tooth portion 210. When Lf2 is less than 0.2*Lf1, that is, the width of the third trimming section 1141 is small, it is easy to interfere with the inner tooth portion 210. When Lf2 is greater than 0.4*Lf1, that is, the width of the third trimming section 1141 is large, when the width of the convex tooth 114 remains unchanged, the width of the middle section 1142 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the outer tooth portion 111 and the inner tooth portion 210, and poor stability during meshing. When Lf3 is less than 0.35*Lf1, that is, the width of the middle section 1142 is small, it will also result in a reduction in the effective meshing area between the outer tooth portion 111 and the inner tooth portion 210, and poor stability during meshing. When Lf3 is greater than 0.45*Lf1, when the width of the convex tooth 114 remains unchanged, the widths of the third trimming sections 1141 and 1143 need to be reduced accordingly, which may easily interfere with the inner tooth portion 210 at the third trimming sections 1141 and 1143. When Lf4 is less than 0.25*Lf1, that is, the width of the third trimming section 1143 is small, which may easily interfere with the inner tooth portion 210. When Lf4 is greater than 0.45*Lf1, that is, the width of the third trimming section 1143 is large, when the width of the convex tooth 114 remains unchanged, the width of the middle section 1142 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the outer tooth portion 111 and the inner tooth portion 210, and poor stability during meshing.

[0137] Therefore, the ratio of the width of the third trimming section 1141 to the width of the convex tooth 114 is set in the range of 0.2 to 0.35, the ratio of the width of the middle section 1142 to the width of the convex tooth 114 is set in the range of 0.35 to 0.45, and the ratio of the width of the third trimming section 1143 to the width of the convex tooth 114 is set in the range of 0.25 to 0.4. While ensuring the meshing stability of the convex tooth 114 and the inner tooth portion 210, the interference between the outer tooth portion 111 and the inner tooth portion 210 can be reduced, thereby reducing the friction and wear of the tooth surface, which is beneficial to extending the life of the flexible wheel 100.

[0138] Reference Fig.23As shown, in the embodiment of the utility model, the tooth top of the third trimming section 1141 is configured as a first inclined surface 11411, and the first inclined surface 11411 is inclinedly arranged in a direction away from the middle section 1142 and in a direction toward the rotation axis O. The tooth top of the third trimming section 1143 is configured as a second inclined surface 11431, and the second inclined surface 11431 is inclinedly arranged in a direction away from the middle section 1142 and in a direction toward the rotation axis O. Among them, the inclination angle of the second inclined surface 11431 is greater than the inclination angle 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 can be understood that when the wave generator 300 is embedded in the inner hole of the cylinder 110, the outer wall of the cylinder 110 will be tilted, that is, an opening angle will be formed. Since the third shaping section 1143 is closer to the flange section 130 than the third shaping section 1141, the third shaping section 1143 is more likely to interfere with the inner tooth 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 shaping section 1143 and the inner tooth portion 210 can be effectively reduced or avoided, and the contact area between the third shaping section 1143 and the inner tooth portion 210 can be increased to improve the stability during power transmission.

[0139] Continue to refer to Fig.23 As shown, in the embodiment of the utility model, in order to further reduce the interference between the outer tooth portion 111 and the inner tooth portion 210, a third inclined surface 1144 is provided between two adjacent third trimming sections 1141, and the third inclined surface 1144 is inclinedly arranged in a direction away from the middle section 1142 and toward the direction of the rotation axis O. A fourth inclined surface 1145 is provided between two adjacent third trimming sections 1143, and the fourth inclined surface 1145 is inclinedly arranged in a direction away from the middle section 1142 and toward the direction of the rotation axis O. Among them, the inclination angle of the third inclined surface 1144 and the inclination angle of the first inclined surface 11411 can be the same or different, and the inclination angle of the fourth inclined surface 1145 and the inclination angle of the second inclined surface 11431 can be the same or different. Thereby, the interference between the tooth top of the inner tooth portion 210 and the tooth root of the outer tooth portion 111 can be effectively reduced or avoided, so as to reduce the friction and wear of the tooth surface and extend the life of the flexible wheel 100.

[0140] Continue to refer to Fig.23As shown, in the embodiment of the utility model, the inclination angle of the first inclined surface 11411 is α1, which satisfies: 0.3°≤α1≤1°, for example, the value of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, 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 inner tooth portion 210 and the outer tooth portion 111. When α1 is greater than 1°, it is easy to cause the effective area of ​​the third trimming section 1141 and the inner tooth portion 210 to be reduced when meshing, thereby causing the stability of the meshing to deteriorate. The inclination angle of the third inclined surface 1144 is α2, which satisfies: 0.3°≤α2≤1°, for example, the value of α2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, 1°. When α2 is less than 0.3°, that is, the inclination angle of the third inclined surface 1144 is too small, it is difficult to reduce the interference between the inner tooth portion 210 and the outer tooth portion 111. When α2 is greater than 1°, it is easy to reduce the strength of the outer tooth portion 111, and it is easy to tear between adjacent convex teeth 114. Therefore, a reasonable design of the size of α1 and α2 can effectively reduce the interference between the inner tooth portion 210 and the outer tooth portion 111, improve the service life of the flexible wheel 100, and at the same time ensure that the outer tooth portion 111 has appropriate strength and high reliability.

[0141] Continue to refer to Fig.23 As shown, in the embodiment of the utility model, the inclination angle of the second inclined surface 11431 is β1, which satisfies: 0.3°≤β1≤1°, for example, the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, 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 inner tooth portion 210 and the outer tooth portion 111. When β1 is greater than 1°, it is easy to cause the effective area of ​​the third trimming section 1143 and the inner tooth portion 210 to be reduced when meshing, thereby causing the stability of the meshing to deteriorate. The inclination angle of the fourth inclined surface 1145 is β2, which satisfies: 0.3°≤β2≤1°, for example, the value of β2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, 1°. When β2 is less than 0.3°, that is, the inclination angle of the fourth inclined surface 1145 is too small, it is difficult to reduce the interference between the inner tooth portion 210 and the outer tooth portion 111. When β2 is greater than 1°, it is easy to reduce the strength of the outer tooth portion 111, and it is easy to tear between adjacent convex teeth 114. Therefore, a reasonable design of the size of β1 and β2 can effectively reduce the interference between the inner tooth portion 210 and the outer tooth portion 111, improve the service life of the flexible wheel 100, and at the same time ensure that the outer tooth portion 111 has appropriate strength and high reliability.

[0142] Wherein, β1≥α1. It is understandable that, since the third trimming section 1143 is closer to the flange portion 130 than the third trimming section 1141, the third trimming section 1143 is more likely to interfere with the inner tooth portion 210, and 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 trimming section 1143 and the inner tooth portion 210 can be effectively reduced or avoided, and the contact area between the third trimming section 1143 and the inner tooth portion 210 can be increased, so as to improve the stability during power transmission.

[0143] Reference Fig.21 As shown, in the embodiment of the present invention, the minimum distance between the end wall of the end of the barrel 110 away from the flange 130 and the flange 130 is Lf, and the maximum length of the inner tooth portion 210 along the axial direction of the rotating shaft is Lc, which satisfies: 0.5*Lf≤Lc≤0.6*Lf, wherein the value of Lc can be 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, 0.6*Lf. When Lc is less than 0.5*Lf, that is, the maximum length of the inner tooth portion 210 is short, resulting in a reduction in the tooth surface contact area between the inner tooth portion 210 and the outer tooth portion 111, an increase in contact stress, and a reduction in the bearing capacity of the harmonic reducer. When Lc is greater than 0.6*Lf, that is, the maximum length of the inner tooth portion 210 is large, the space occupied is too much, and the strength margin is too large, which is not conducive to the miniaturization design of the harmonic reducer. Therefore, a reasonable design of the maximum length Lc and Lf of the inner tooth portion 210 can effectively increase the tooth surface contact area between the inner tooth portion 210 and the outer tooth portion 111, reduce the contact stress, improve the load-bearing capacity of the harmonic reducer, and at the same time facilitate the miniaturization design of the harmonic reducer.

[0144] Continue to refer to Fig.21As shown, in the embodiment of the present invention, the minimum distance between the end wall of the barrel 110 away from the flange 130 and the flange 130 is Lf, and along the direction parallel to the rotation axis O of the wave generator 300, the tooth width of the convex tooth 114 is Lf1, which satisfies: 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, 0.55*Lf. When Lf1 is less than 0.45*Lf, that is, the tooth width of the convex tooth 114 is small, resulting in a reduction in the tooth surface contact area between the inner tooth portion 210 and the outer tooth portion 111, an increase in contact stress, and a reduction in the load-bearing capacity of the harmonic reducer. When Lf1 is greater than 0.6*Lf, that is, the tooth width of the convex tooth 114 is larger, and the space occupied is more, which is not conducive to the flexible deformation of the barrel 110, resulting in a decrease in the toughness of the flexible wheel 100. Therefore, by reasonably designing the proportional relationship between Lf1 and Lf, the tooth surface contact area between the inner tooth portion 210 and the outer tooth portion 111 can be increased, the contact stress can be reduced, and the load-bearing capacity of the harmonic reducer can be improved, while also ensuring that the flexible wheel 100 has appropriate toughness.

[0145] Reference Fig.21 As shown, in the embodiment of the utility model, the tooth width Lf1 of the convex tooth 114 is smaller than the maximum length Lc of the inner tooth portion 210. It is understandable that the flexible wheel 100 has axial movement during operation, and due to the influence of processing errors, if the tooth width Lf1 of the convex tooth 114 is larger than the maximum length Lc of the inner tooth portion 210, it is easy to cause a part of the structure of the convex tooth 114 to be out of meshing state, affecting the meshing stability. The harmonic reducer mainly checks the stability of the flexible wheel 100, so the tooth width Lf1 of the convex tooth 114 is designed to be smaller than the maximum length Lc of the inner tooth portion 210, which can improve the meshing stability and reliability of the flexible wheel 100.

[0146] Table 1: Comparison of tooth surface contact area of ​​different schemes

[0147]

[0148] For example, referring to Table 1 above, Scheme 1 is a scheme in the related art, Lc=0.42*Lf, Lf1=0.36*Lf, and the tooth height of the convex tooth 114 remains unchanged, that is, no tooth modification is used; Scheme 2 is Lc=0.55*Lf, Lf1=0.5*Lf, and the tooth height of the convex tooth 114 remains unchanged, that is, no tooth modification is used; Scheme 3 is Lc=0.55*Lf, Lf1=0.5*Lf, and the convex tooth 114 is provided with a third modification section 1141 and a third modification section 1143. It can be seen from Table 1 above that when Lc=0.55*Lf and Lf1=0.5*Lf are designed, the tooth surface contact area can be increased by 18.3%, and on this basis, the modification scheme is added, which is 32.6% higher than that of 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.

[0149] An industrial robot in one embodiment of the utility model comprises a motor and the harmonic reducer of the above embodiment. It is understandable that the motor can be a servo motor, and the servo motor drive is connected to the harmonic reducer to perform deceleration control on the joints of the industrial robot. The industrial robot can be a handling robot, a welding robot, an assembly robot, a processing robot, a spraying robot, a cleaning robot, a collaborative robot, etc.

[0150] The industrial robot of the embodiment of the utility model adopts the harmonic reducer of the above embodiment, and the harmonic reducer is provided with a bearing device 400 that is conveniently assembled with the rigid wheel 200 and the flexible wheel 100, and 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 bodies 460 and a plurality of second rolling bodies 470, the inner bearing ring 410 is fixedly connected to the rigid wheel 200 and is provided with a first raceway 411 and a third raceway 4211 at 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, and the first outer bearing ring 421 is provided with a third raceway 460 opposite to the first raceway 411. 211, the second outer bearing ring 422 is provided with a fourth raceway 4221 opposite to the third raceway 4211, a plurality of first rolling elements 460 are installed in a first annular space formed between the first raceway 411 and the third raceway 4211, a plurality of second rolling elements 470 are installed in a second annular space formed between the third raceway 4211 and the fourth raceway 4221, and the raceways in the first annular space and the raceways in the second annular space are both complete raceways. The structure of providing two sets of complete raceways and two sets of rolling elements can effectively improve the carrying capacity of the harmonic reducer, while maintaining the compactness of the overall structure, improve the assembly efficiency between the bearing device 400 and the rigid wheel 200 and the flexible wheel 100, and facilitate production scheduling.

[0151] The industrial robot of the embodiment of the utility model adopts all the technical solutions of the harmonic reducer of the above embodiment, and therefore has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here.

[0152] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. Harmonic reducer, characterized in that: include: A rigid wheel having an internal tooth portion; The flexible wheel comprises a cylinder portion and a flange portion, wherein the cylinder portion is provided with an outer tooth portion matching with the inner tooth portion; A wave generator is coaxially mounted on the inner hole of the flexspline; A bearing device is used to support the rigid wheel and the flexible wheel so that they can rotate relative to each other, and the bearing device includes 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 to the rigid wheel, and the inner bearing ring is provided with a first raceway and a second raceway at two ends opposite to each other along the rotation axis of the wave generator, respectively, and the first raceway and the second raceway are annular and arranged at intervals; 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 on the outside of the first raceway and opposite to the first raceway, and the second outer bearing ring is provided with a fourth raceway located on the outside of 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.

2. The harmonic reducer according to claim 1, characterized in that: The inner hole diameter of the flexible wheel is Df, and the maximum cross-sectional diameter of the first rolling element is Db1, which satisfies: 0.07*Df≤Db1≤0.13*Df.

3. The harmonic reducer according to claim 1, characterized in that: The inner hole diameter of the flexible wheel is Df, and in the direction perpendicular to the rotation axis, the diameter of the circle where the centers of the plurality of first rolling elements are located is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df.

4. The harmonic reducer according to claim 1, characterized in that: The minimum distance between the end wall of the cylinder away from the flange and the flange is Lf, and 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, satisfying: 0.2*Lf≤L1≤0.28*Lf.

5. The harmonic reducer according to claim 1, characterized in that: The minimum distance between the end wall of the cylinder away from the flange portion and the flange portion is Lf, the first outer bearing ring is provided with a first end face, the first end face abuts against the flange portion, and the maximum distance between the first end face and the center of the first rolling element is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

6. The harmonic reducer according to claim 1, characterized in that: In a cross section passing through the rotation axis, the outer contour line of the first raceway is a first curve, the first curve includes a first circular arc segment and a first modified segment, and the first modified segment is a non-circular arc.

7. The harmonic reducer according to claim 6, characterized in that: The radius of the first 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 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 satisfies the equation: ρi = Ri+ ki *Ri*[sin(90°*θ / βi)-1], when 0°≤θ≤βi; ρi = Ri, when θ>βi; Among them, Ri = (0.505-0.515)*Db1, ki=0.002-0.004, βi=20°-30°.

8. The harmonic reducer according to claim 1, 6 or 7, characterized in that: In a cross section passing through the rotation axis, the outer contour line of the third raceway is a second curve, the second curve includes a second circular arc segment and a second modified segment, and the second modified segment is a non-circular arc.

9. The harmonic reducer according to claim 8, characterized in that: 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°.

10. The harmonic reducer according to claim 1, characterized in that: A first step is provided on a side of the first outer bearing ring 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 a side of the inner bearing ring close to the second raceway, a second step is provided on a side of the rigid wheel 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 via a second fastener.

11. The harmonic reducer according to claim 1, characterized in that: 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, a first gap is provided between the outer bearing ring and the inner bearing ring on a side of the second oil storage space close to the first oil storage space, and a second gap is provided between the outer bearing ring and the flexible wheel on a side of the second oil storage space away from the first oil storage space; The harmonic reducer also includes a first oil seal and a second oil seal. The first oil seal is installed in the first gap and is used to prevent the lubricant in the first oil storage space from exchanging with the lubricant in the second oil storage space. The second oil seal is installed in the second gap and is used to prevent the lubricant in the second oil storage space from overflowing.

12. The harmonic reducer according to claim 11, characterized in that: The inner wall of the first outer bearing ring is provided with a protrusion extending toward the rotation axis, and the inner bearing ring is provided with a step portion spaced apart from the protrusion, and the first gap is formed between the protrusion and the step portion; the first oil seal includes 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.

13. The harmonic reducer according to claim 12, characterized in that: The first oil seal also includes a second lip, and the mounting ring includes a first ring body and a second ring body, the first ring body is clamped to the end of the protrusion toward one end of the rotation axis, the second ring body is connected to the first ring body and extends toward the direction of 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 toward the inner bearing ring to seal the gap between the second ring body and the inner bearing ring.

14. The harmonic reducer according to claim 13, characterized in that: The first ring body is provided with a stop shoulder, and the stop shoulder is located on the side wall of the protruding portion facing the inner bearing ring to limit the first oil seal from escaping in a direction away from the inner bearing ring.

15. An industrial robot, characterized in that: Including the harmonic reducer according to any one of claims 1 to 14.

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