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 the harmonic wave speed reducer includes flexible gear, rigid gear, wave generator and support bearing, flexible gear and rigid gear can realize relative rotation through support bearing, support bearing includes outer ring body, inner ring body, outer ring body and inner ring body. And a plurality of first rolling bodies and a plurality of second rolling bodies, the inner side of the outer ring body is provided with two first roller paths which are arranged along the rotating axis of the flexible gear at intervals and are opposite to each other, the outer side of the inner ring body is provided with two second roller paths which are arranged along the rotating axis at intervals and are opposite to each other, and a plurality of first rolling bodies are installed between one pair of the first roller path and the second roller path which are matched with each other. And a plurality of second rolling bodies are arranged between the other pair of matched first roller path and second roller path, so that the supporting bearing can improve the bearing capacity of the harmonic speed reducer and reduce the vibration and noise of the whole harmonic speed reducer by arranging a matching structure of the two pairs of roller paths and the two groups of rolling bodies, and is convenient to assemble.

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] Harmonic reduction drive is a new type of mechanical transmission that relies on the controllable elastic deformation of flexible gears to transmit motion and force. Harmonic reducers generally include a wave generator, a flexible wheel, a rigid wheel and a support bearing; when the wave generator rotates, the flexible wheel is forced to produce elastic deformation, so that the teeth of the flexible wheel interact with the teeth of the rigid wheel, thereby achieving the purpose of reduction transmission. Harmonic reducers are widely used in robotics, electronics, aerospace, automation and other industries due to their compact structure, small size, light weight, large transmission ratio and load capacity, and high transmission accuracy.

[0003] At present, harmonic reducers generally use single-row crossed roller bearings as support bearings. To facilitate the filling of rollers during bearing assembly, roller filling ports need to be set on the inner or outer rings of the crossed roller bearings. However, the integrity of the raceway is destroyed due to the roller filling ports, which reduces the smoothness of the roller operation and makes the overturning moment and overturning moment rigidity of the harmonic reducer unable to meet the requirements in special scenarios such as heavy loads. Utility Model Content

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a harmonic reducer with high load-bearing capacity.

[0005] The utility model also provides an industrial robot having the harmonic reducer.

[0006] According to the first aspect of the utility model, the harmonic reducer comprises: a flexible wheel provided with an external tooth portion; a rigid wheel provided with an internal tooth portion; a wave generator installed in the inner hole of the flexible wheel, the wave generator being configured to mesh the external tooth portion with the internal tooth portion when rotating; a support bearing being configured to enable the flexible wheel and the rigid wheel to rotate relative to each other, the support bearing comprising an outer ring body, an inner ring body, and a plurality of first rolling elements and a plurality of second rolling elements, the outer ring body being fixedly connected to the flexible wheel, the inner side of the outer ring body being provided with two first raceways spaced apart and arranged opposite to each other along the rotation axis of the flexible wheel, the inner ring body being fixedly connected to the rigid wheel, the outer side of the inner ring body being provided with two second raceways spaced apart and arranged opposite to each other along the rotation axis, the plurality of first rolling elements being installed between the first raceway and the second raceway on the side close to the external tooth portion along the direction of the rotation axis, and the plurality of second rolling elements being installed between the first raceway and the second raceway on the side away from the external tooth portion along the direction of the rotation axis.

[0007] The harmonic reducer according to the embodiment of the utility model has at least the following beneficial effects:

[0008] By setting a support bearing including an outer ring body, an inner ring body, and a plurality of first rolling bodies and a plurality of second rolling bodies rollingly arranged between the outer ring body and the inner ring body, the outer ring body is fixedly connected to the flexible wheel, the inner ring body is fixedly connected to the rigid wheel, and the flexible wheel and the rigid wheel can achieve relative rotation through the support bearing; the inner side of the outer ring body is provided with two first raceways spaced and arranged opposite to each other along the rotation axis of the flexible wheel, and the outer side of the inner ring body is provided with two second raceways spaced and arranged opposite to each other along the rotation axis, wherein a plurality of first rolling bodies are installed between a pair of matching first raceways and second raceways, and a plurality of second rolling bodies are installed between another pair of matching first raceways and second raceways, so that the support bearing can improve the load-bearing capacity of the harmonic reducer by setting a matching structure of two pairs of raceways and two groups of rolling bodies, while maintaining the compactness of the overall structure of the harmonic reducer. The support bearing of this embodiment is easy to assemble, and the raceway matched with the rolling body is complete, which is conducive to reducing the overall vibration and noise of the harmonic reducer.

[0009] According to some embodiments of the utility model, the maximum width of the flexible wheel along the rotation axis is Lf, the wave generator includes a cam and a flexible bearing sleeved on the outside of the cam, the flexible bearing includes a ball, and the offset of the center of the first rolling body and the center of the ball in the direction of the rotation axis is La, satisfying: -0.1*Lf≤La≤0.1*Lf.

[0010] 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: 0.08*Df≤Db1≤0.13*Df.

[0011] 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: 1.4*Df≤Db2≤1.7*Df.

[0012] According to some embodiments of the present invention, the maximum width of the flexible wheel along the rotation axis is Lf, and the maximum distance between the center of the first rolling body and the center of the second rolling body parallel to the rotation axis is Lr, satisfying: 0.4*Lf≤Lr≤0.7*Lf.

[0013] According to some embodiments of the present invention, in a cross section passing through the rotation axis, an outer contour line of the first raceway cooperating with the first rolling element 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.

[0014] According to some embodiments of the present invention, the radius of the first arc segment is Ri, and a coordinate system is established with the center of the first arc segment as the origin. The X-axis is parallel to the rotation axis and points in the direction of the second rolling body, and the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis. The first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ / 20°)-1], when 0°≤θ≤βi; ρi=Ri, when θ>βi; wherein, Ri=(0.505-0.515)*Db1, ki=0.002-0.004, βi=20°-30°.

[0015] According to some embodiments of the present invention, in a cross section passing through the rotation axis, the outer contour line of the second raceway cooperating with the first rolling element is a second curve, the second curve includes a second arc segment and a second modified segment, and the second modified segment is a non-circular arc.

[0016] According to some embodiments of the present invention, the radius of the second arc segment is Ro, and a coordinate system is established with the center of the second arc segment as the origin. The X-axis is parallel to the rotation axis and points in the direction away from the second rolling body, and the Y-axis is perpendicular to the X-axis and points in the direction of the rotation axis. The second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ / 20°)-1], when 0°≤θ≤βo; ρo=Ro, when θ>βo; wherein, Ro=(0.505-0.515)*Db1, ko=0.002-0.004, βo=20°-30°.

[0017] According to some embodiments of the utility model, the wave generator includes a camshaft and a flexible bearing sleeved on the outside of the camshaft; the harmonic reducer also includes: a first bearing seat, fixedly connected to the flexible wheel and the outer ring body, the first bearing seat is supported at one end of the camshaft along the direction of the rotation axis through a first bearing; a second bearing seat, fixedly connected to the rigid wheel and the inner ring body, the second bearing seat is supported at the other end of the camshaft along the direction of the rotation axis through a second bearing.

[0018] According to some embodiments of the utility model, the flexible wheel includes a flange portion, the first bearing seat abuts against one side of the flange portion, the outer ring body abuts against the other side of the flange portion, and the first bearing seat, the flange portion and the outer ring body are connected by fasteners.

[0019] According to some embodiments of the utility model, the inner ring body includes a first inner ring and a second inner ring, the first inner ring abuts against one side of the rigid wheel, the second bearing seat abuts against the other side of the rigid wheel, the first inner ring, the rigid wheel and the second bearing seat are connected by fasteners; the second inner ring is sleeved on the outer side of the rigid wheel.

[0020] According to some embodiments of the present invention, the outer peripheral wall of the inner ring body is provided with a sink groove, and the sink groove forms two second raceways along two side walls on the rotation axis respectively.

[0021] According to some embodiments of the present invention, the first raceway is provided with a first surface texture, and the first surface texture comprises a plurality of first depressions arranged at intervals.

[0022] According to some embodiments of the present invention, the first depression is hemispherical, the depth of the first depression is 2 μm to 10 μm, and the port diameter of the first depression is 50 μm to 200 μm.

[0023] According to some embodiments of the present invention, the second raceway is provided with a second surface texture, and the second surface texture includes a plurality of second depressions arranged at intervals.

[0024] According to some embodiments of the present invention, the second recess is hemispherical, the depth of the second recess is 2 μm to 10 μm, and the port diameter of the second recess is 50 μm to 200 μm.

[0025] According to some embodiments of the utility model, the first raceway is provided with a first surface texture, and the total area of ​​the first surface texture accounts for 10% to 20% of the area of ​​the raceway; and / or, the second raceway is provided with a second surface texture, and the total area of ​​the second surface texture accounts for 10% to 20% of the area of ​​the raceway.

[0026] The industrial robot according to the embodiment of the second aspect of the utility model includes the harmonic reducer described in the above embodiment.

[0027] The industrial robot according to the embodiment of the utility model has at least the following beneficial effects:

[0028] The harmonic reducer of the first embodiment is adopted, and the harmonic reducer is provided with a support bearing including an outer ring body, an inner ring body, and a plurality of first rolling bodies and a plurality of second rolling bodies rollingly arranged between the outer ring body and the inner ring body, the outer ring body is fixedly connected to the flexible wheel, the inner ring body is fixedly connected to the rigid wheel, and the flexible wheel and the rigid wheel can realize relative rotation through the support bearing; the inner side of the outer ring body is provided with two first raceways spaced and arranged oppositely along the rotation axis of the flexible wheel, and the outer side of the inner ring body is provided with two second raceways spaced and arranged oppositely along the rotation axis, wherein a plurality of first rolling bodies are installed between a pair of matching first raceways and second raceways, and a plurality of second rolling bodies are installed between another pair of matching first raceways and second raceways, so that the support bearing can improve the load-bearing capacity of the harmonic reducer by providing a matching structure of two pairs of raceways and two groups of rolling bodies, thereby improving the load-bearing capacity of the industrial robot. The support bearing of this embodiment is easy to assemble, and the raceway matched with the rolling body is complete, which is conducive to reducing the vibration and noise of the whole machine of the harmonic reducer, thereby effectively reducing the running noise of the industrial robot.

[0029] 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

[0030] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0031] Figure 1 This is a structural cross-sectional view of a harmonic reducer according to an embodiment of the utility model;

[0032] Figure 2 for Figure 1 The enlarged view of point A in the middle;

[0033] Figure 3 for Figure 1 The diagram showing the marking of various parameters of the harmonic reducer shown;

[0034] Figure 4 This is a cross-sectional view of an outer ring body in a harmonic reducer according to an embodiment of the utility model;

[0035] Figure 5 for Figure 4 The enlarged view of point B in the middle;

[0036] Figure 6 This is a front view of the inner ring body of a harmonic reducer in one embodiment of the utility model;

[0037] Figure 7 for Figure 6 Enlarged view of point C in the middle;

[0038] Figure 8This is a cross-sectional view of an outer ring body in a harmonic reducer according to an embodiment of the utility model;

[0039] Fig. 9 for Figure 8 The enlarged view of point D in the middle;

[0040] Fig.10 This is a front view of the inner ring body of a harmonic reducer in another embodiment of the utility model;

[0041] Fig.11 for Fig.10 Enlarged view of point E in the middle;

[0042] Fig.12 This is a relationship diagram between the ratio of La and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the support bearing, and the length of the entire machine body;

[0043] Fig.13 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 support bearing and the weight of the whole machine;

[0044] Fig.14 This 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 support bearing and the weight of the whole machine;

[0045] Fig.15 A graph showing the relationship between the ratio of Lr to Lf, the allowable torque of the support bearing and the length of the entire machine body in a harmonic reducer according to an embodiment of the utility model;

[0046] Fig.16 This is a comparison diagram of the overturning moment rigidity before and after the raceway modification in a harmonic reducer of an embodiment of the utility model.

[0047] Figure Number:

[0048] Wave generator 100; flexible bearing 110; third rolling element 111; camshaft 120;

[0049] Flexspline 200; external tooth portion 210; cylinder portion 220; flange portion 230;

[0050] The rigid wheel 300; the inner tooth portion 310;

[0051] Support bearing 400; outer ring 410; first raceway 411; avoidance notch 412; first surface texture 413; first depression 4131; inner ring 420; second raceway 421; first inner ring 422; second inner ring 423; sink 424; second surface texture 425; second depression 4251; first rolling element 430; second rolling element 440; first curve 450; first arc segment 451; first trimming segment 452; second curve 460; second arc segment 461; second trimming segment 462;

[0052] First bearing seat 500; first bearing 510;

[0053] Second bearing seat 600; second bearing 610;

[0054] Axis of rotation O. DETAILED DESCRIPTION

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] As a kind of precision reducer, harmonic reducer has the advantages of compact structure, small size, light weight, large transmission ratio and load capacity, and high transmission accuracy. It is widely used in electronics, aerospace, robotics, automation and other industries.

[0060] Reference Figure 1As shown, a harmonic reducer of an embodiment of the utility model includes a wave generator 100, a flexible wheel 200 and a rigid wheel 300. The flexible wheel 200 is provided with a flexible outer tooth portion 210, and the rigid wheel 300 is provided with a rigid inner tooth portion 310, and the outer tooth portion 210 can cooperate with the inner tooth portion 310. The wave generator 100 of the utility model embodiment includes a flexible bearing 110 and a camshaft 120, and the flexible bearing 110 is sleeved on the outer side of the camshaft 120. As another embodiment, the wave generator 100 may also include a flexible bearing 110 and a cam, and the flexible bearing 110 is sleeved on the cam, and the cam is provided with a mounting position for connecting a driving device such as a motor.

[0061] In the embodiment of the utility model, the wave generator 100 is installed in the inner hole of the flexible wheel 200, and the flexible wheel 200 includes a barrel 220 and a flange 230. The barrel 220 is generally cylindrical, one end of the barrel 220 is connected to the flange 230, and the outer peripheral wall of the other end of the barrel 220 is provided with the outer tooth portion 210; the inner hole of the flexible wheel 200 is the inner hole of the barrel 220, and the wave generator 100 is installed in the inner hole of the part of the barrel 220 provided with the outer tooth portion 210.

[0062] When the wave generator 100 is installed into the inner hole of the cylinder 220, the flexible spline 200 is forced to undergo elastic deformation and become elliptical. During the operation of the harmonic reducer, the wave generator 100 rotates at a high speed, thereby driving the flexible spline 200 to undergo repeated deformation, so that the outer tooth portion 210 of the flexible spline 200 meshes with the inner tooth portion 310 of the rigid wheel 300, and the meshing position of the outer tooth portion 210 and the inner tooth portion 310 moves along the circumferential direction of the rotation axis O of the flexible spline 200, thereby achieving relative deceleration motion between the flexible spline 200 and the rigid wheel 300.

[0063] Reference Figure 1As shown, the harmonic reducer of an embodiment of the utility model further includes a support bearing 400, which is used to support the flexible wheel 200 and the rigid wheel 300, so that the flexible wheel 200 and the rigid wheel 300 can rotate stably. It can be understood that the support bearing 400 includes an outer ring body 410 and an inner ring body 420, and the outer ring body 410 is sleeved on the outer side of the inner ring body 420; the support bearing 400 also includes two groups of rolling bodies installed between the outer ring body 410 and the inner ring body 420, one group is composed of a plurality of first rolling bodies 430 and a first retaining frame, and the other group is composed of a plurality of second rolling bodies 440 and a second retaining frame. The outer ring body 410 is fixedly connected to the flexible wheel 200, and the inner ring body 420 is fixedly connected to the rigid wheel 300. Under the cooperation of the two groups of rolling bodies and the outer ring body 410 and the inner ring body 420, the flexible wheel 200 and the rigid wheel 300 can achieve relative rotation through the support bearing 400. It is understood that the first rolling body 430 can be a sphere, or a cylinder, cone or other cylindrical body; the second rolling body 440 can be a sphere, or a cylinder, cone or other cylindrical body, which is not specifically limited here. In addition, in this embodiment, the first rolling body 430 and the second rolling body 440 can be made of metal materials such as steel.

[0064] Reference Figure 1 and Figure 2 As shown, the inner side of the outer ring body 410 is provided with two first raceways 411 spaced apart from each other along the rotation axis O of the flexible wheel 200, and the two first raceways 411 are arranged in opposite directions; Figure 2 As shown, the opening of the first raceway 411 located on the left side faces the left side, and the opening of the first raceway 411 located on the right side faces the right side. The outer side of the inner ring body 420 is provided with two second raceways 421 spaced apart along the rotation axis O, and the two second raceways 421 are arranged facing each other; Figure 2 As shown, the opening of the second raceway 421 located on the left side faces right, and the opening of the second raceway 421 located on the right side faces left. A plurality of first rolling bodies 430 and a first retaining frame are installed between a pair of matching first raceways 411 and second raceways 421 located on the right side, that is, a plurality of first rolling bodies 430 are installed on the side close to the outer tooth portion 210 along the direction of the rotation axis O. A plurality of second rolling bodies 440 and a second retaining frame are installed between a pair of matching first raceways 411 and second raceways 421 located on the left side, that is, a plurality of first rolling bodies 430 are installed on the side away from the outer tooth portion 210 along the direction of the rotation axis O.

[0065] The support bearing 400 of the embodiment of the utility model can increase the span of the harmonic reducer through two pairs of raceways and two groups of rolling elements, thereby improving the bearing capacity of the harmonic reducer, meeting the requirements of high overturning moment and high overturning moment rigidity of the harmonic reducer, and maintaining the compactness of the overall structure of the harmonic reducer. Moreover, the support bearing 400 of the embodiment of the utility model can be installed in place step by step when assembling the outer ring body 410, the inner ring body 420 and the rolling element, and there is no need to set a filling port, so the installation of the rolling element is more convenient, thereby reducing the difficulty of assembly; the first raceway 411 of the outer ring body 410 and the second raceway 421 of the inner ring body 420 have no filling port, avoiding the problem that each time the roller passes through the filling port in the traditional cross roller bearing, a vibration excitation is generated, eliminating an internal excitation from the structural design, ensuring the integrity of the raceway, improving the smoothness of the rolling element during operation, and being conducive to reducing the overall vibration and noise of the harmonic reducer, reducing the wear of the harmonic reducer, reducing the failure rate of the harmonic reducer, and improving the service life of the harmonic reducer.

[0066] It is understandable that the harmonic reducer of the embodiment of the utility model also includes a body, and the body and the outer ring body 410 are an integrally formed part; as another embodiment, the body and the outer ring body 410 can also be fixedly connected by fasteners such as screws and pins.

[0067] Reference Figure 1 As shown, the harmonic reducer of the embodiment of the utility model further includes a first bearing seat 500 and a second bearing seat 600. Since the body and the outer ring body 410 of the embodiment are an integrally formed part, for the convenience of description, the outer ring body 410 is used as the above-mentioned integrally formed part. The first bearing seat 500 and the second bearing seat 600 are respectively located on the left and right sides of the flexible wheel 200. The first bearing seat 500 is fixedly connected to the flexible wheel 200 and the outer ring body 410, and the first bearing seat 500 is supported on the camshaft 120 by the first bearing 510 on the side facing the camshaft 120. The second bearing seat 600 is fixedly connected to the rigid wheel 300 and the inner ring body 420, and the second bearing seat 600 is supported on the camshaft 120 by the second bearing 610 on the side facing the camshaft 120. The first bearing 510 and the second bearing 610 are located at both ends of the camshaft 120 along the direction of the rotation axis O, and the flexible bearing 110 is located between the first bearing 510 and the second bearing 610.

[0068] In the embodiment of the utility model, the first bearing 510 and the second bearing 610 are both deep groove ball bearings, so that the first bearing 510 and the second bearing 610 can withstand axial force and radial force, thereby improving the installation stability of the first bearing seat 500 and the second bearing seat 600. In order to improve assembly efficiency and reduce the types of accessories, the first bearing 510 and the second bearing 610 use deep groove ball bearings of the same model.

[0069] Reference Figure 1 As shown, it can be understood that in order to improve the convenience of assembly, the first bearing seat 500 abuts against one side of the flange portion 230 of the flexible wheel 200, and the outer ring body 410 abuts against the other side of the flange portion 230. The first bearing seat 500, the flange portion 230 and the outer ring body 410 are connected by fasteners, so that the installation of the support bearing 400 and the flexible wheel 200 is more stable, thereby making the operation of the harmonic reducer more stable.

[0070] Reference Figure 1 As shown, it can be understood that the inner ring body 420 includes a first inner ring 422 and a second inner ring 423, and the first inner ring 422 and the second inner ring 423 can be arranged at intervals or can be arranged to abut against each other. In this embodiment, in order to improve the convenience of assembly, the first inner ring 422 abuts against one side of the rigid wheel 300, and the second bearing seat 600 abuts against the other side of the rigid wheel 300. The first inner ring 422, the rigid wheel 300 and the second bearing seat 600 are connected by fasteners; the second inner ring 423 is sleeved on the outer side of the rigid wheel 300, for example, by means of interference connection, bonding, etc. Fixed connection. Therefore, the inner ring body 420 with the above structure makes the installation of the support bearing 400 and the rigid wheel 300 more stable, so that the operation of the harmonic reducer is more stable.

[0071] Reference Figure 1 and Figure 2 As shown, it can be understood that in order to reduce the radial size of the harmonic reducer and realize the miniaturization of the harmonic reducer, the outer peripheral wall of the inner ring body 420 is provided with a sink groove 424, and the sink groove 424 forms two second raceways 421 along the two side walls in the direction of the rotation axis O. In this embodiment, the first inner ring 422 has a part of the sink groove 424, and forms the second raceway 421 on the side wall away from the second inner ring 423; the second inner ring 423 has another part of the sink groove 424, and forms the second raceway 421 on the side wall away from the first inner ring 422. Therefore, the processing of the two second raceways 421 is more convenient and the processing accuracy is higher.

[0072] Reference Figure 1 and Figure 3As shown, the inner diameter of the flexible wheel 200 is defined as Df. The maximum cross-sectional diameter of the first rolling element 430 is defined as Db1, that is, the diameter of the maximum cross-sectional area of ​​the first rolling element 430 perpendicular to the rotation axis O; for example, when the first rolling element 430 is a sphere, Db1 is the diameter of the sphere, and when the first rolling element 430 is a cylinder, Db1 is the diameter of the largest cross-sectional area among all cross-sectional areas perpendicular to the axis of the cylinder. The first rolling elements 430 are arranged at intervals along the circumference of the rotation axis O, and the diameter of the circle where the centers of the first rolling elements 430 are located in the direction perpendicular to the rotation axis O is defined as Db2.

[0073] The maximum width of the flexible spline 200 along the direction of the rotation axis O is defined as Lf. Lf is related to the performance of the flexible spline 200; the larger the Lf, the greater the flexibility of the flexible spline 200; conversely, the smaller the Lf, the greater the rigidity of the flexible spline 200.

[0074] The plurality of second rolling bodies 440 are arranged at intervals along the axial direction of the rotation axis O. The maximum distance between the center of the first rolling body 430 and the center of the second rolling body 440 is defined as Lr between the two first rolling bodies 430 and the second rolling body 440 parallel to the rotation axis O. Lr is related to the bearing span; the larger the Lr, the larger the bearing span, and the better the anti-overturning ability of the support bearing 400; conversely, the smaller the Lr, the smaller the bearing span, and the worse the anti-overturning ability of the support bearing 400.

[0075] Reference Figure 3 As shown, it can be understood that the flexible bearing 110 of the wave generator 100 includes a third rolling body 111, and the third rolling body 111 can be a structure such as a ball, a needle or a roller, which is not specifically limited here. In the embodiment of the utility model, the third rolling body 111 is a ball, and the offset between the center of the ball and the center of the third rolling body 111 in the direction of the rotation axis O is La, which satisfies: -0.1*Lf≤La≤0.1*Lf; the value of La can be: -0.1*Lf, -0.05*Lf, 0, 0.05*Lf, 0.1*Lf, etc. It is defined that when the first rolling body 430 deviates to the left, the offset La is a negative number; when the first rolling body 430 deviates to the right, the offset La is a positive number.

[0076] Fig.12 The figure is a relationship diagram between the ratio of La and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the support bearing 400, and the length of the whole machine body. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Fig.12As shown in the figure, when the offset La is a positive number, as La / Lf increases, the length of the whole body of the harmonic reducer increases rapidly, while the allowable torque increases slowly; when the offset La is a negative number, as the offset La / Lf decreases, the length of the whole body remains basically unchanged, while the allowable torque decreases rapidly. Therefore, by weighing the requirements of the whole body length and the allowable torque of the harmonic reducer, the offset La is set at -0.1*Lf to 0.1*Lf, which can meet the requirements of the maximum overturning moment and the length of the whole body at the same time.

[0077] Reference Figure 3 As shown, it can be understood that the inner hole diameter Df of the flexible wheel 200 and the maximum cross-sectional diameter Db1 of the first rolling element 430 satisfy: 0.08*Df≤Db1≤0.13*Df; the value of Db1 can be: 0.08*Df, 0.09*Df, 0.1*Df, 0.11*Df, 0.13*Df, etc. Fig.13 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 support bearing 400, and the weight of the whole machine. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Fig.13 As shown in the figure, when Db1 / Df is less than 0.08, 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 430 is set to 0.08*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.

[0078] Reference Figure 3 As shown, it can be understood that the inner hole diameter Df of the flexible wheel 200, in the direction perpendicular to the rotation axis O, and the diameter Db2 of the circle where the centers of the plurality of first rolling elements 430 are located, satisfy: 1.4*Df≤Db2≤1.7*Df; the value of Db2 can be: 1.4*Df, 1.5*Df, 1.6*Df, 1.7*Df, etc. Fig.14 The figure is a relationship diagram between the ratio of Db2 and Df in a harmonic reducer of an embodiment of the present utility model, the allowable torque of the support bearing 400, and the weight of the whole machine. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Fig.14As shown, when Db2 / Df is less than 1.4, 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 430 is located is set to 1.4*Df to 1.7*Df, which can meet the requirements of the maximum overturning moment and the weight of the whole machine at the same time.

[0079] Reference Figure 3 As shown, it can be understood that the maximum width Lf of the flexible wheel 200 along the direction of the rotation axis O and the maximum distance Lr between the center of the first rolling body 430 and the center of the second rolling body 440 parallel to the rotation axis O satisfy: 0.4*Lf≤Lr≤0.7*Lf; the value of Lf can be: 0.4*Lf, 0.5*Lf, 0.6*Lf, 0.7*Lf. Fig.15 The figure is a relationship diagram between the ratio of Lr and Lf in a harmonic reducer of an embodiment of the utility model, the allowable torque of the support bearing 400, and the length of the whole machine body. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Fig.15 As shown, when Lr / Lf is less than 0.4, the length of the whole body of the harmonic reducer remains basically unchanged, but the allowable torque decreases rapidly and cannot meet the use requirements. When Lr / Lf is greater than 0.7, although the allowable torque continues to increase, the length of the whole body increases rapidly and cannot meet the use requirements. Therefore, by weighing the requirements of the whole body length and the allowable torque of the harmonic reducer, the maximum distance Lr between the center of the first rolling element 430 and the center of the second rolling element 440 parallel to the rotation axis O is set at 0.4*Lf to 0.7*Lf, which can simultaneously meet the requirements of the maximum overturning moment and the length of the whole body.

[0080] Reference Figure 4 and Figure 5As shown, it can be understood that, in the cross section passing through the rotation axis O, the outer contour line of the first raceway 411 matched with the first rolling body 430 is a first curve 450. Compared with the arc-shaped raceway in the related art, the first raceway 411 of this embodiment is reshaped. Specifically, the first curve 450 includes a first arc segment 451 and a first reshaped segment 452, and the first reshaped segment 452 is a non-circular arc. Through the reshaped first raceway 411, when subjected to a large overturning moment, the contact area between the first rolling body 430 and the first raceway 411 is larger, which can reduce the contact stress between the first rolling body 430 and the first raceway 411, thereby improving the bearing capacity of the overall overturning moment and overturning moment rigidity of the support bearing 400.

[0081] Reference Figure 5 As shown, it can be understood that the radius of the first arc segment 451 is defined as Ri, a coordinate system is established with the center of the first arc segment 451 as the origin, and the X-axis is parallel to the rotation axis O and points to the direction of the second rolling body 440 (i.e. Figure 5 The Y axis is perpendicular to the X axis and points away from the rotation axis O (i.e. Figure 5 The first curve 450 satisfies the equation:

[0082] ρi=Ri+ki*Ri*[sin(90°*θ / 20°)-1], when 0°≤θ≤βi;

[0083] ρi=Ri, when θ>βi;

[0084] Among them, Ri = (0.505-0.515)*Db1; ki = 0.002-0.004, for example, ki takes values ​​of 0.002, 0.003, and 0.004; βi = 20°-30°, for example, βi takes values ​​of 20°, 25°, and 30°.

[0085] The embodiment of the utility model designs the first curve 450 so that when the first raceway 411 is subjected to a large overturning moment, there is multi-point contact between the first rolling body 430 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 body 430 and the first raceway 411 in the related art (before shaping).

[0086] For example, when the support bearing 400 is subjected to force, the first rolling element 430 and the first raceway 411 will deform. Before the modification, the first rolling element 430 and the first raceway 411 have a single point contact at a position of about 40°; however, after the modification, the first rolling element 430 and the first raceway 411 not only have contact at a position of about 40°, but also have contact between 10° and 20°.

[0087] 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 support bearing 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 of the overturning moment becomes smaller; according to the overturning moment rigidity = overturning moment / angle of the overturning moment, when the overturning moment is constant, the smaller the angle of 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%.

[0088] It can be understood that the outer contour line of the first raceway 411 cooperating with the second rolling body 440 is a third curve. The third curve and the first curve 450 are symmetrical with respect to the symmetry center line of the first rolling body 430 and the second rolling body 440. Therefore, it can be understood by referring to the equation of the first curve 450. In order to avoid repetition, it will not be repeated here.

[0089] Reference Figure 5 As shown, the two first raceways 411 are respectively provided with avoidance notches 412 on the sides close to each other. The setting of the avoidance notches 412 helps the rollers to enter the first raceways 411 for processing, thereby improving the processing convenience and processing accuracy of the first raceways 411.

[0090] Reference Figure 6 and Figure 7 As shown, it can be understood that, in the cross section passing through the rotation axis O, the outer contour line of the second raceway 421 matched with the first rolling body 430 is a second curve 460. Since the second raceway 421 is located outside the inner ring body 420 and the second raceway 421 is annular, the outer contour line formed by the second raceway 421 in the front view of the inner ring body 420 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 front view of the inner ring body 420 as an example. The second curve 460 includes a second arc segment 461 and a second trimming segment 462, and the second trimming segment 462 is a non-circular arc. Compared with the arc-shaped raceway in the related art, the second raceway 421 of this embodiment is trimmed. Through the modified second raceway 421, when subjected to a larger overturning moment, the contact area between the first rolling element 430 and the second raceway 421 is larger, which can reduce the contact stress between the first rolling element 430 and the second raceway 421, thereby improving the overall overturning moment and overturning moment rigidity and other bearing capacities of the support bearing 400.

[0091] Reference Figure 7As shown, it can be understood that the radius of the second arc segment 461 is Ro, and a coordinate system is established with the center of the second arc segment 461 as the origin, and the X-axis is parallel to the rotation axis O and points away from the second rolling element 440 (i.e. Figure 7 The Y axis is perpendicular to the X axis and points to the direction of the rotation axis O (i.e. Figure 7 In the downward direction), the second curve 460 satisfies the equation:

[0092] ρo=Ro+ko*Ro*[sin(90°*θ / 20°)-1], when 0°≤θ≤βo;

[0093] ρo=Ro,when θ>βo;

[0094] Among them, Ro = (0.505-0.515)*Db1; ko = 0.002-0.004, for example, ko takes values ​​of 0.002, 0.003, and 0.004; βo = 20°-30°, for example, βo takes values ​​of 20°, 25°, and 30°.

[0095] The embodiment of the utility model designs the second curve 460 so that when the second raceway 421 is subjected to a large overturning moment, there is multi-point contact between the first rolling element 430 and the second raceway 421, 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 430 and the second raceway 421 in the related art (before shaping).

[0096] For example, when the support bearing 400 is subjected to force, the first rolling element 430 and the second raceway 421 will deform. Before the modification, the first rolling element 430 and the second raceway 421 have a single point contact at a position of about 40°; however, after the modification, the first rolling element 430 and the second raceway 421 have a single point contact at a position of about 40° and also have a contact between 10° and 20°.

[0097] Fig.16 This is a comparison diagram of the overturning moment rigidity of the second raceway 421 before and after the modification in a harmonic reducer of an embodiment of the utility model. Fig.16 As shown, after the second raceway 421 is modified, when the support bearing 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 of the overturning moment becomes smaller; according to the overturning moment rigidity = overturning moment / angle of the overturning moment, when the overturning moment is constant, the smaller the angle of the overturning moment, the greater the overturning moment rigidity. Therefore, after the second raceway 421 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%.

[0098] It can be understood that the outer contour line of the second raceway 421 cooperating with the second rolling body 440 is a fourth curve, and the fourth curve and the second curve 460 are symmetrical with respect to the symmetry center line of the first rolling body 430 and the second rolling body 440. Therefore, it can be understood by referring to the equation of the second curve 460. In order to avoid repetition, it will not be repeated here.

[0099] Reference Figure 8 and Fig. 9 As shown, in another embodiment of the harmonic reducer of the utility model, the first raceway 411 is provided with a first surface texture 413, and the first surface texture 413 includes a plurality of first recesses 4131 arranged at intervals. The first surface texture 413 is provided on the first raceway 411. Due to the presence of the first recesses 4131, the contact area between the first rolling body 430, the second rolling body 440 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 4131, which inhibits the abrasive particles from entering the contact surface between the first raceway 411 and the first rolling body 430, the second rolling body 440, 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 413 can also store lubricant. When the first rolling body 430 and the second rolling body 440 squeeze the first raceway 411, the first raceway 411 will be slightly deformed, and the lubricant in the first recess 4131 will be squeezed out to supplement lubrication. It can improve the lubrication conditions and reduce the risk of fatigue fracture of the first raceway 411, thereby improving the vibration and noise performance of the harmonic reducer and enhancing the load-bearing capacity of the whole machine.

[0100] Reference Fig. 9 As shown, it can be understood that the first depression 4131 is hemispherical, and the depth of the first depression 4131 is 2μm to 10μm. It can be understood that when the depth of the first depression 4131 is too small, for example, less than 2μm, it is easy to be ground by the first rolling body 430 and the second rolling body 440, 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 when the depth is too small, it is difficult to process. When the depth of the first depression 4131 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.

[0101] The port diameter of the first depression 4131 is 50 μm to 200 μm. When the port diameter of the first depression 4131 is less than 50 μm, the ability to store abrasive particles and lubricants is low; the port diameter of the first depression 4131 is related to the contact width of the first rolling body 430, the second rolling body 440 and the first raceway 411. When the port diameter of the first depression 4131 is greater than 200 μm, that is, greater than the contact width of the first rolling body 430, the second rolling body 440 and the first raceway 411, the first rolling body 430 and the second rolling body 440 run unsteadily, and the wear is aggravated.

[0102] Therefore, by designing the first recess 4131 according to the above parameters, the first recess 4131 can have a good ability to store abrasive particles and lubricants, and can improve the oil film bearing capacity.

[0103] Reference Fig.10 and Fig.11 As shown, in another embodiment of the harmonic reducer of the utility model, the second raceway 421 is provided with a second surface texture 425, and the second surface texture 425 includes a plurality of second recesses 4251 arranged at intervals. The second surface texture 425 is provided on the second raceway 421. Due to the presence of the second recesses 4251, the contact area between the first rolling body 430, the second rolling body 440 and the second raceway 421 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 second recesses 4251, which inhibits the abrasive particles from entering the contact surface of the second raceway 421 and the first rolling body 430, the second rolling body 440, thereby inhibiting the abrasive particles from aggravating the raceway wear, thereby reducing the appearance of the white layer of the second raceway 421. The second surface texture 425 can also store lubricant. When the first rolling body 430 and the second rolling body 440 squeeze the second raceway 421, the second raceway 421 will be slightly deformed, and the lubricant in the second recess 4251 will be squeezed out to supplement lubrication. It can improve the lubrication conditions and reduce the risk of fatigue fracture of the second raceway 421, thereby improving the vibration and noise performance of the harmonic reducer and enhancing the load-bearing capacity of the whole machine.

[0104] Reference Fig.11 As shown, it can be understood that the second depression 4251 is hemispherical, and the depth of the second depression 4251 is 2μm to 10μm. It can be understood that if the depth of the second depression 4251 is too small, for example, less than 2μm, it is easy to be worn flat by the first rolling body 430 and the second rolling body 440, 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 second depression 4251 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 second raceway 421.

[0105] The port diameter of the second depression 4251 is 50 μm to 200 μm. When the port diameter of the second depression 4251 is less than 50 μm, the ability to store abrasive particles and lubricants is low; the port diameter of the second depression 4251 is related to the contact width of the first rolling element 430, the second rolling element 440 and the second raceway 421. When the port diameter of the second depression 4251 is greater than 200 μm, that is, greater than the contact width of the first rolling element 430, the second rolling element 440 and the second raceway 421, the first rolling element 430 and the second rolling element 440 run unsteadily, and the wear is aggravated.

[0106] Therefore, by designing the second recess 4251 according to the above parameters, the second recess 4251 can have a good ability to store abrasive particles and lubricants, and can improve the oil film bearing capacity.

[0107] Reference Figure 8 As shown, the first raceway 411 of the embodiment of the utility model is provided with a first surface texture 413, and the total area of ​​the first surface texture 413 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 413 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 413 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.

[0108] Reference Fig.10 As shown, the second raceway 421 of the embodiment of the utility model is provided with a second surface texture 425, and the total area of ​​the second surface texture 425 accounts for 10% to 20% of the area of ​​the second raceway 421. It can be understood that when the total area of ​​the second surface texture 425 accounts for too small an area of ​​the second raceway 421, 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 second surface texture 425 accounts for 10% to 20%, which can enable the second raceway 421 to have good anti-friction ability and lubricant storage ability, and solve the white layer problem of the second raceway 421.

[0109] After experimental comparison, the harmonic reducer of the embodiment of the utility model is compared with the traditional harmonic reducer using cross roller bearings, with the same size and mass: 1) the allowable overturning moment is increased by more than 50%; 2) the overturning moment rigidity is increased by more than 40%; 3) the vibration acceleration is reduced by more than 20%; 4) the noise is reduced by more than 3dBA.

[0110] 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.

[0111] 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 an outer ring body 410, an inner ring body 420, and a support bearing 400 including a plurality of first rolling bodies 430 and a plurality of second rolling bodies 440 rollingly arranged between the outer ring body 410 and the inner ring body 420. The outer ring body 410 is fixedly connected to the flexible wheel 200, and the inner ring body 420 is fixedly connected to the rigid wheel 300. The flexible wheel 200 and the rigid wheel 300 can realize relative rotation through the support bearing 400. The inner side of the outer ring body 410 is provided with two rotation bearings along the flexible wheel 200. The first raceway 411 is arranged spaced apart and away from each other on the axis O, and the outer side of the inner ring body 420 is provided with two second raceways 421 spaced apart and facing each other along the rotation axis O, wherein a plurality of first rolling bodies 430 are installed between a pair of matched first raceways 411 and second raceways 421, and a plurality of second rolling bodies 440 are installed between another pair of matched first raceways 411 and second raceways 421, so the support bearing 400 can improve the carrying capacity of the harmonic reducer by setting the matching structure of two pairs of raceways and two groups of rolling bodies, thereby improving the carrying capacity of the industrial robot. The support bearing 400 of this embodiment is easy to assemble, and the raceway matched with the rolling body is complete, which is conducive to reducing the vibration and noise of the whole machine of the harmonic reducer, thereby effectively reducing the operating noise of the industrial robot.

[0112] 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.

[0113] 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 flexible wheel having an external tooth portion; A rigid wheel having an internal tooth portion; a wave generator mounted in the inner hole of the flexspline, the wave generator being configured to mesh the outer tooth portion with the inner tooth portion when rotating; The support bearing is configured to enable the flexible wheel and the rigid wheel to rotate relative to each other, and the support bearing includes an outer ring body, an inner ring body, and a plurality of first rolling elements and a plurality of second rolling elements. The outer ring body is fixedly connected to the flexible wheel, and the inner side of the outer ring body is provided with two first raceways spaced apart and arranged opposite to each other along the rotation axis of the flexible wheel. The inner ring body is fixedly connected to the rigid wheel, and the outer side of the inner ring body is provided with two second raceways spaced apart and arranged opposite to each other along the rotation axis. The plurality of first rolling elements are installed between the first raceway and the second raceway on the side close to the outer tooth portion along the direction of the rotation axis, and the plurality of second rolling elements are installed between the first raceway and the second raceway on the side away from the outer tooth portion along the direction of the rotation axis.

2. The harmonic reducer according to claim 1, characterized in that: The maximum width of the flexible wheel along the direction of the rotation axis is Lf, the wave generator includes a cam and a flexible bearing sleeved on the outside of the cam, the flexible bearing includes a ball, and the offset of the center of the first rolling body and the center of the ball in the direction of the rotation axis is La, satisfying: -0.1*Lf≤La≤0.1*Lf.

3. 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: 0.08*Df≤Db1≤0.13*Df.

4. 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: 1.4*Df≤Db2≤1.7*Df.

5. The harmonic reducer according to claim 1, characterized in that: The maximum width of the flexible wheel along the rotation axis is Lf, and the maximum distance between the center of the first rolling element and the center of the second rolling element parallel to the rotation axis is Lr, which satisfies: 0.4*Lf≤Lr≤0.7*Lf.

6. The harmonic reducer according to claim 1, characterized in that: In a cross section passing through the rotation axis, an outer contour line of the first raceway matched with the first rolling element 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, and 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 element. The Y-axis is perpendicular to the X-axis and points away from the rotation axis. The first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ / 20°)-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, characterized in that: In the cross section passing through the rotation axis, the outer contour line of the second raceway matched with the first rolling element is a second curve, the second curve includes a second 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, and 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 in the direction of the rotation axis. The second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ / 20°)-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: The wave generator includes a camshaft and a flexible bearing sleeved on the outside of the camshaft; the harmonic reducer also includes: A first bearing seat, fixedly connected to the flexible wheel and the outer ring body, wherein the first bearing seat is supported by a first bearing at one end of the camshaft along the direction of the rotation axis; The second bearing seat is fixedly connected to the rigid wheel and the inner ring body, and the second bearing seat is supported by the other end of the camshaft along the direction of the rotation axis through a second bearing.

11. The harmonic reducer according to claim 10, characterized in that: The flexible wheel includes a flange portion, the first bearing seat abuts against one side of the flange portion, the outer ring body abuts against the other side of the flange portion, and the first bearing seat, the flange portion and the outer ring body are connected by fasteners.

12. The harmonic reducer according to claim 10 or 11, characterized in that: The inner ring body comprises a first inner ring and a second inner ring, the first inner ring abuts against one side of the rigid wheel, the second bearing seat abuts against the other side of the rigid wheel, and the first inner ring, the rigid wheel and the second bearing seat are connected by fasteners; The second inner ring is sleeved on the outer side of the rigid wheel.

13. The harmonic reducer according to claim 11, characterized in that: The outer peripheral wall of the inner ring body is provided with a sink groove, and the sink groove forms two second raceways along two side walls on the rotation axis respectively.

14. The harmonic reducer according to claim 1, characterized in that: The first raceway is provided with a first surface texture, and the first surface texture comprises a plurality of first depressions arranged at intervals.

15. The harmonic reducer according to claim 14, characterized in that: The first recess is hemispherical, the depth of the first recess is 2 μm to 10 μm, and the port diameter of the first recess is 50 μm to 200 μm.

16. The harmonic reducer according to claim 1, characterized in that: The second raceway is provided with a second surface texture, and the second surface texture comprises a plurality of second depressions arranged at intervals.

17. The harmonic reducer according to claim 16, characterized in that: The second recess is hemispherical, the depth of the second recess is 2 μm to 10 μm, and the port diameter of the second recess is 50 μm to 200 μm.

18. The harmonic reducer according to claim 1, characterized in that: The first raceway is provided with a first surface texture, and the total area of ​​the first surface texture accounts for 10% to 20% of the area of ​​the raceway; and / or, The second raceway is provided with a second surface texture, and the total area of ​​the second surface texture accounts for 10% to 20% of the area of ​​the raceway.

19. An industrial robot, characterized in that: Including the harmonic reducer according to any one of claims 1 to 18.

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