Harmonic speed reducer and industrial robot

Abstract

The utility model discloses a harmonic speed reducer and an industrial robot, and relates to the technical field of speed reducers, the harmonic speed reducer comprises a rigid gear, a flexible gear, a wave generator and a support bearing, the wave generator is arranged in the flexible gear, and an outer tooth part of the flexible gear is partially meshed with an inner tooth part of the rigid gear; a first groove body and a second groove body are arranged between an inner bearing ring and an outer bearing ring of the supporting bearing, the first groove body is used for installing the first rolling body, and the second groove body is used for installing the second rolling body. The bearing capacity of the harmonic speed reducer can be effectively improved by arranging the two sets of rolling bodies. And meanwhile, the ratio of the tooth root wall thickness Tf of the flexible gear to the inner hole diameter Df of the flexible gear is set to be 0.0043 Ln (R)-0.0061 and 0.005 Ln (R)-0.0036, so that the stress distribution of harmonic speed reducers with different reduction ratios R is improved, and the stress borne by the flexible gear during deformation is reduced.

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, the harmonic reducer includes a wave generator, a flexspline and a rigid wheel. The wave generator is embedded in the inner hole of the flexspline, and the outer teeth of the flexspline are meshed with the inner teeth of the rigid wheel. When the wave generator rotates, it can drive different parts of the outer teeth and the inner teeth to mesh, thereby causing relative rotation between the rigid wheel and the flexspline to achieve power output. The flexspline will undergo reciprocating deformation during operation and will be subject to stress. Therefore, when designing the flexspline, it is necessary to reduce the stress generated when the flexspline deforms as much as possible. Although flexsplines of the same specifications have the same inner hole diameter, due to different reduction ratios, the number of teeth and module of the flexspline are also different, resulting in different deformations of the flexspline. Therefore, it is difficult to design a suitable structure for the flexspline to reduce the stress it is subjected to when it deforms. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a harmonic reducer that can effectively reduce the stress on the flexible wheel during deformation.

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

[0005] According to an embodiment of the first aspect of the present invention, a harmonic reducer includes: a rigid wheel including an internal tooth portion; a flexible wheel arranged inside the rigid wheel, the flexible wheel including an external tooth portion; a wave generator arranged inside the flexible wheel and used to partially mesh the external tooth portion with the internal tooth portion; a support bearing configured to enable the rigid wheel and the flexible wheel to rotate relative to each other, the support bearing including an outer bearing ring and an inner bearing ring arranged inside the outer bearing ring, a first groove body for mounting a first rolling element and a second groove body for mounting a second rolling element are provided between the inner bearing ring and the outer bearing ring, the first groove body and the second groove body are arranged at intervals along the axial direction of the wave generator; wherein the tooth root wall thickness of the flexible wheel is Tf, the inner hole diameter of the flexible wheel is Df, the reduction ratio of the harmonic reducer is R, and the following conditions are satisfied: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036.

[0006] The harmonic reducer according to the embodiment of the utility model has at least the following beneficial effects:

[0007] By positioning the wave generator inside the flexspline and partially meshing the outer teeth of the flexspline with the inner teeth of the rigid wheel, rotation of the wave generator drives the flexspline and the rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the support bearing. The first groove accommodates a first rolling element, while the second groove accommodates a second rolling element. The first and second grooves are spaced axially along the wave generator. The two sets of rolling elements effectively enhance the load-bearing capacity of the harmonic reducer, improving assembly efficiency between the bearing assembly, the rigid wheel, and the flexspline while maintaining the overall compactness of the unit. Furthermore, by setting the ratio of the flexspline tooth root wall thickness Tf to the flexspline inner hole diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the stress distribution of harmonic reducers with different reduction ratios R is improved, reducing the stress on the flexspline during deformation.

[0008] According to some embodiments of the present invention, along the axial direction, the effective width of the flexspline is Lf, and the width of the inner tooth portion is Lc, which satisfies: 0.45*Lf≤Lc≤0.65*Lf.

[0009] According to some embodiments of the present invention, the rigid wheel also includes a first mounting portion connected to the inner bearing ring, the inner tooth portion is connected to the inner side of the first mounting portion, and along the axial direction of the wave generator, the width of the inner tooth portion is greater than the width of the first mounting portion.

[0010] According to some embodiments of the present invention, the portion of the inner tooth portion protruding from the first mounting portion along the axial direction abuts against the inner side of the inner bearing ring; one end of the inner bearing ring along the axial direction is provided with a protrusion protruding toward the first mounting portion, and the inner side of the protrusion abuts against the outer side of the first mounting portion.

[0011] According to some embodiments of the present invention, the first mounting portion is connected to an end of the inner tooth portion that is away from the inner bearing ring along the axial direction.

[0012] According to some embodiments of the present invention, the flexible wheel also includes a cylinder, a diaphragm and a flange, the external tooth portion is connected to the outer side of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, the flange portion is connected to the end of the diaphragm away from the cylinder, and the flange portion is fixedly connected to the outer bearing ring.

[0013] According to some embodiments of the present invention, along the axial direction of the wave generator, the first rolling element is located between the diaphragm and the inner tooth portion, the width of the inner tooth portion is Lc, and the minimum distance between the end surface of the inner tooth portion facing the first rolling element and the center of the second rolling element is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc, wherein when L3>0, the center of the second rolling element is located between the two end surfaces of the outer tooth portion along the axial direction, and when L3<0, the center of the second rolling element is located between the outer tooth portion and the diaphragm.

[0014] According to some embodiments of the present invention, along the axial direction, the external tooth portion includes a first tooth segment away from one end of the flange portion and a second tooth segment close to one end of the flange portion, the diameter of the tooth top circle of the first tooth segment gradually decreases in the direction away from the flange portion, and the diameter of the tooth top circle of the second tooth segment gradually decreases in the direction toward the flange portion.

[0015] According to some embodiments of the present invention, the external tooth portion further includes a third tooth segment located between the first tooth segment and the second tooth segment, and the diameter of the tooth top circle of the third tooth segment is constant.

[0016] According to some embodiments of the present invention, along the axial direction, the effective width of the flexible spline is Lf, the width of the outer tooth portion is Lf1, the width of the first tooth segment is Lf2, the width of the second tooth segment is Lf4, and the width of the third tooth segment is Lf3, satisfying the following: 0.4*Lf≤Lf1≤0.6*Lf; 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

[0017] According to some embodiments of the present invention, the inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.3°≤α1≤1.0°, 0.3°≤β1≤1.0°, and β1≥α1.

[0018] According to some embodiments of the present invention, the flexible wheel further includes a cylinder, a diaphragm and a flange, the external tooth portion is connected to the outer side of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, the flange portion is connected to the end of the diaphragm away from the cylinder, the flange portion and the outer bearing ring are fixedly connected, the effective width of the flexible wheel along the axial direction is Lf, the maximum distance between the end wall of the outer bearing ring abutting against one end of the flange portion and the center of the first rolling element is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf; and / or, the effective width of the flexible wheel along the axial direction is Lf, and in a direction parallel to the axial direction, the maximum distance between the center of the first rolling element and the center of the second rolling element is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

[0019] According to some embodiments of the present invention, the outer bearing ring includes a second mounting portion and a raised portion connected to the inner side of the second mounting portion, and the raised portion is respectively provided with a first outer raceway and a second outer raceway at both ends along the axial direction, which are opposite to each other; the outer side of the inner bearing ring is provided with a groove arranged opposite to the raised portion, and the two ends of the groove along the axial direction are respectively the first inner raceway and the second inner raceway; the first inner raceway and the first outer raceway are arranged opposite to each other and form the first groove body, and the second inner raceway and the second outer raceway are arranged opposite to each other and form the second groove body.

[0020] According to some embodiments of the present invention, there is a gap between the protrusion and the bottom wall of the groove, and the first groove body and the second groove body are connected through the gap.

[0021] According to some embodiments of the present invention, the inner bearing ring includes a first ring body and a second ring body connected to each other, the first inner raceway is arranged on the outside of the first ring body and close to the second ring body, the second inner raceway is arranged on the outside of the second ring body and away from the first ring body, and the second ring body is connected to the rigid wheel.

[0022] According to some embodiments of the present invention, in a cross-section passing through the rotation axis of the wave generator, the outer contour line of the first inner raceway is a first curve, the first curve includes a first arc segment and a first modified segment, and the first modified segment is a non-circular arc; the radius of the first arc segment is Ri, the maximum cross-sectional diameter of the first rolling element is Db1, 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 away from the second rolling element, the Y-axis is perpendicular to the X-axis and points in the direction of the rotation axis, and the first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi=Ri, when θ1>βi; wherein, Ri=(0.505~0.515)*Db1, ki=0.002~0.004, βi=20°-30°.

[0023] According to some embodiments of the present invention, in a cross-section passing through the rotation axis of the wave generator, the outer contour line of the first outer raceway 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; the radius of the second arc segment is Ro, the maximum cross-sectional diameter of the first rolling element is Db1, 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 of the second rolling element, the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis, and the second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; wherein, Ro=(0.505~0.515)*Db1, ko=0.002~0.004, βo=20°-30°.

[0024] According to some embodiments of the present invention, the inner hole diameter of the flexible wheel is Df, the maximum cross-sectional diameter of the first rolling element is Db1, and the following conditions are satisfied: 0.07*Df≤Db1≤0.13*Df; and / or, the inner hole diameter of the flexible wheel is Df, and the diameter of the circle in which the centers of the plurality of first rolling elements are located in a direction perpendicular to the axial direction is Db2, and the following conditions are satisfied: 1.3*Df≤Db2≤1.7*Df.

[0025] The industrial robot according to the embodiment of the second aspect of the present utility model includes the harmonic reducer described in the above embodiment.

[0026] The industrial robot according to the embodiment of the present utility model has at least the following beneficial effects:

[0027] A harmonic reducer according to the first embodiment is configured such that a wave generator is positioned within the flexspline, with the outer teeth of the flexspline partially meshing with the inner teeth of the rigid wheel. Rotation of the wave generator drives the flexspline and the rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the support bearing. The first groove is for mounting a first rolling element, and the second groove is for mounting a second rolling element. The first and second grooves are spaced apart along the axial direction of the wave generator. The provision of two sets of rolling elements effectively improves the load-bearing capacity of the harmonic reducer, while maintaining the overall compactness of the structure and enhancing the assembly efficiency between the bearing assembly, the rigid wheel, and the flexspline. Furthermore, by setting the ratio of the flexspline tooth root wall thickness Tf to the flexspline inner hole diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the stress distribution of harmonic reducers with different reduction ratios R is improved, reducing the stress on the flexspline during deformation.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0030] Figure 1 This is a schematic cross-sectional view of the structure of a harmonic reducer according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic cross-sectional view of a portion of the structure of a flexible pulley according to an embodiment of the present invention;

[0032] Figure 3 This is a partial structural diagram of a flexible pulley according to an embodiment of the present invention;

[0033] Figure 4 for Figure 1 Enlarged view of point A in the middle;

[0034] Figure 5 This is a schematic cross-sectional view of a portion of the outer tooth portion of an embodiment of the present invention;

[0035] Figure 6 This is a schematic cross-sectional view of a portion of the outer tooth portion of an embodiment of the present invention;

[0036] Figure 7 This is a schematic structural diagram of an inner bearing ring according to an embodiment of the present invention;

[0037] Figure 8 for Figure 7 Enlarged view of point B in the middle;

[0038] Figure 9 This is a cross-sectional view of an outer bearing ring according to an embodiment of the present invention;

[0039] Figure 10 for Figure 9 Enlarged view of point C in the middle;

[0040] Figure 11 This is a relationship diagram between the ratio of Tf / Df and the flexspline tooth root stress according to an embodiment of the present invention;

[0041] Figure 12 This is a relationship diagram of the ratio L3 / Lc, the weight of the entire machine, and the vibration acceleration of an embodiment of the present utility model;

[0042] Figure 13 This is a relationship diagram of the ratio L1 / Lf, the allowable torque of the support bearing, and the weight of the entire machine in one embodiment of the present utility model;

[0043] Figure 14 This is a relationship diagram of the ratio L2 / Lf, the allowable torque of the support bearing, and the weight of the entire machine in one embodiment of the present utility model;

[0044] Figure 15 This is a comparison diagram of the overturning moment rigidity before and after raceway modification in a harmonic reducer according to an embodiment of the present invention;

[0045] Figure 16 This is a relationship diagram of the ratio Db1 / Df, the allowable torque of the bearing device, and the weight of the entire machine in a harmonic reducer according to an embodiment of the present invention;

[0046] Figure 17 This is a relationship diagram of the ratio Db2 / Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing device, and the weight of the entire machine.

[0047] Figure Number:

[0048] Harmonic reducer 1000;

[0049] The circular gear 100; the inner tooth portion 110; the first mounting portion 120;

[0050] Flexspline 200 ; external tooth portion 210 ; first tooth segment 211 ; first inclined surface 2111 ; second inclined surface 2112 ; second tooth segment 212 ; third inclined surface 2121 ; fourth inclined surface 2122 ; third tooth segment 213 ; cylinder portion 220 ; diaphragm portion 230 ; flange portion 240 ;

[0051] Wave generator 300; cam 310; flexible bearing 320;

[0052] Support bearing 400; outer bearing ring 410; second mounting portion 411; raised portion 412; first outer raceway 413; second arc segment 4131; second modified segment 4132; second curve 4133; second outer raceway 414; inner bearing ring 420; protrusion 421; groove 422; first inner raceway 423; first arc segment 4231; first modified segment 4232; first curve 4233; second inner raceway 424; first ring body 425; second ring body 426; first groove body 430; first rolling element 431; second groove body 440; second rolling element 441;

[0053] Oil seal 500. DETAILED DESCRIPTION

[0054] The following describes embodiments of the present invention in detail. 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 intended only to explain the present invention and are not to be construed as limiting the present invention.

[0055] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying 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.

[0056] In the description of this utility model, "a plurality" means more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0057] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting 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.

[0058] Reference Figure 1 and Figure 2As shown, a harmonic reducer 1000 according to an embodiment of the present invention includes a flexspline 200, a rigid wheel 100, and a wave generator 300. The flexspline 200 is coaxially mounted within the rigid wheel 100, and the wave generator 300 is coaxially mounted within the inner bore of the flexspline 200. The flexspline 200 includes a barrel 220, a diaphragm 230, and a flange 240. The barrel 220 is located at the end of the flexspline 200 that is close to the rigid wheel 100. The diaphragm 230 is connected to the end of the barrel 220 that is away from the rigid wheel 100 and extends radially from the barrel 220. The flange 240 is connected to the outer periphery of the diaphragm 230. The barrel 220 of the flexspline 200 is provided with a flexible outer tooth portion 210. The outer tooth portion 210 is a structure that protrudes radially outward from the barrel 220. The outer tooth portion 210 is not formed within the inner bore of the flexspline 200, but rather on the outer wall of the barrel 220. The rigid wheel 100 is provided with a rigid inner tooth portion 110 , and the outer tooth portion 210 cooperates with the inner tooth portion 110 , and a meshing gap is formed between the outer tooth portion 210 and the inner tooth portion 110 .

[0059] In this embodiment of the present invention, the wave generator 300 is interference-fitted into the inner bore of the flexspline 200. Rotation of the wave generator 300 causes the outer teeth 210 to partially engage with the inner teeth 110. Partial engagement refers to the circumferential deformation of the outer teeth 210 of the flexspline 200, which results in the partial engagement of the deformed portions of the outer teeth 210 with corresponding portions of the inner teeth 110. Specifically, the meshing positions of the inner and outer teeth 110 and 210 cyclically move along the circumferential direction. When the wave generator 300 is installed in the inner bore of the flexspline 200, it forces the flexspline 200 to elastically deform and assume an elliptical shape. During operation of harmonic reducer 1000, wave generator 300 rotates at high speed, causing flexspline 200 to repeatedly deform, causing the outer teeth 210 of flexspline 200 to mesh with the inner teeth 110 of rigid wheel 100. The meshing position of the outer teeth 210 and the inner teeth 110 moves circumferentially along the rotation axis of wave generator 300, thereby achieving relative deceleration motion between flexspline 200 and rigid wheel 100. Wave generator 300 includes a flexible bearing 320 and a cam 310. The flexible bearing 320 is mounted on the outside of the cam 310, while the cam 310 has a mounting position for connecting to a drive device such as a motor.

[0060] Reference Figure 1As shown, a harmonic reducer 1000 according to an embodiment of the present invention further includes a support bearing 400, which is configured to enable relative rotation between the rigid wheel 100 and the flexible wheel 200. The support bearing 400 includes a first rolling element 431, a second rolling element 441, an outer bearing ring 410, and an inner bearing ring 420 disposed within the outer bearing ring 410. An annular first groove 430 and an annular second groove 440 are disposed between the inner bearing ring 420 and the outer bearing ring 410. Along the axial direction of the wave generator 300, the first groove 430 is located on the side away from the rigid wheel 100, and the second groove 440 is located on the side close to the rigid wheel 100 and spaced apart from the first groove 430. That is, the first groove 430 is located on the left side of the harmonic reducer 1000, and the second groove 440 is located on the right side of the harmonic reducer 1000. Multiple first rolling elements 431 are provided and mounted in the first groove 430; multiple second rolling elements 441 are provided and mounted in the second groove 440. The inner bearing ring 420 is fixedly connected to the rigid spline 100, while the outer bearing ring 410 is fixedly connected to the flange 240 of the flexspline 200. This connection can be achieved through fasteners (such as screws, bolts, pins, etc.), or by clamping, bonding, or other methods. Therefore, the coordination of the first rolling elements 431, the second rolling elements 441, the inner bearing ring 420, and the outer bearing ring 410 facilitates relative rotation between the flexspline 200 and the rigid spline 100.

[0061] By employing two sets of rolling elements, consisting of a plurality of first rolling elements 431 and a plurality of second rolling elements 441, the bearing assembly's load-bearing capacity can be improved compared to single-row crossed roller bearings in related art. Furthermore, the structure of the inner bearing ring 420 and the outer bearing ring 410 facilitates assembly of the harmonic reducer 1000 and makes it easier to adapt to different loads. It is understood that the first rolling elements 431 can be spheres, cylinders, cones, or other cylindrical objects; and the second rolling elements 441 can be spheres, cylinders, cones, or other cylindrical objects, without further limitation. Furthermore, in this embodiment, the first and second rolling elements 431, 441 can be made of metal materials such as steel.

[0062] The inner diameter of the flexible wheel 200 of the same specification is the same, and the outer dimensions are basically the same. When the reduction ratio of the harmonic reducer 1000 is different, the number of teeth and the module of the flexible wheel 200 are usually different, so that the stress on the flexible wheel 200 when deforming is also different. In order to reduce the stress on the flexible wheel 200 when deforming and simplify the design of the flexible wheel 200 of the same specification but different reduction ratios, refer to Figure 1 and Figure 3As shown, in the embodiment of the present invention, the tooth root wall thickness of the flexspline 200 is Tf. The tooth root wall thickness Tf refers to the distance between the tooth root of the outer tooth portion 210 and the inner hole wall of the flexspline 200 along the radial direction of the flexspline 200. The inner hole diameter of the flexspline 200 is Df. The reduction ratio of the harmonic reducer 1000 is R, which satisfies the following: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036. The reduction ratio R can be obtained from the parameters marked on the nameplate of the harmonic reducer 1000.

[0063] Reference Figure 11 As shown, Figure 11 The horizontal axis of the graph represents the value of Tf / Df, and the vertical axis represents the tooth root stress of the flexspline 200. As can be seen from the graph, as the value of Tf / Df gradually increases, the tooth root stress of the flexspline 200 first decreases and then increases, reaching a minimum value. Therefore, for flexsplines 200 of the same specification but different reduction ratios, using the natural logarithm function Ln(R) to eliminate the influence of the reduction ratio R, simply by limiting the value of Tf / Df to between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, can effectively reduce the stress on the flexspline 200. This can also simplify the design of the flexspline 200, improve production efficiency, and is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R, reducing the stress on the flexspline 200 during deformation. At the same time, compared with the flexible spline in the related art, the tooth root wall thickness Tf of the flexible spline 200 of this embodiment is increased, which can effectively improve the load-bearing capacity and torsional stiffness of the harmonic reducer 1000 .

[0064] Reference Figure 2As shown, in the embodiment of the present invention, along the axial direction of the wave generator 300, the effective width of the flexible wheel 200 is Lf. The effective width of the flexible wheel 200 refers to the minimum distance between the end face of the end of the cylinder 220 facing away from the flange 240 and the flange 240. The width of the inner tooth portion 110 is Lc. The width of the inner tooth portion 110 refers to the maximum length of the inner tooth portion 110 along the axial direction, for example, the distance between the two farthest end faces of the rigid wheel 100 along the axial direction. The relationship between Lf and Lc satisfies: 0.45*Lf≤Lc≤0.65*Lf. Among them, the value of Lc can be 0.45*Lf, 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, 0.65*Lf. When Lc is less than 0.45*Lf, that is, the maximum length of the inner tooth portion 110 is short, resulting in a decrease in the tooth surface contact area between the inner tooth portion 110 and the outer tooth portion 210, an increase in contact stress, and a reduction in the load-bearing capacity of the harmonic reducer 1000. When Lc is greater than 0.65*Lf, that is, the maximum length of the inner tooth portion 110 is large, occupying too much space and having a large strength margin, which is not conducive to the miniaturization design of the harmonic reducer 1000. Therefore, a reasonable design of the difference between the maximum length Lc and Lf of the inner tooth portion 110 can effectively increase the tooth surface contact area between the inner tooth portion 110 and the outer tooth portion 210, reduce contact stress, improve the load-bearing capacity of the harmonic reducer 1000, and at the same time be conducive to the miniaturization design of the harmonic reducer 1000.

[0065] It should be noted that the inner hole of the flexspline 200 is circular when not installed with the wave generator 300. Once the flexspline 200 and the wave generator 300 are assembled, the outer tooth portion 210 of the flexspline 200 becomes elliptical. Due to the structure of the flexspline 200, the deformation of the outer tooth portion 210 varies along the axial direction at different cross-sections, with the deformation increasing the closer to the opening of the barrel 220. Generally, the meshing state of the middle tooth segment of the outer tooth portion 210 along the axial direction is optimal. The tooth segment near the flange 240 is more likely to interfere with the tooth top of the inner tooth portion 110 of the rigid wheel 100 or have an insufficient clearance, resulting in abnormal friction, wear, and noise. The tooth segment away from the flange 240 is more likely to interfere with the tooth root or middle portion of the inner tooth portion 110 of the rigid wheel 100, similarly resulting in abnormal friction, wear, and noise.

[0066] In order to improve the situation that the outer tooth portion 210 easily interferes with the inner tooth portion 110, causing friction, wear and noise, refer to Figure 4As shown, in an embodiment of the present invention, the rigid pulley 100 further includes a first mounting portion 120. The first mounting portion 120 is annular and connected to the inner bearing ring 420. The first mounting portion 120 and the inner bearing ring 420 can be connected by fasteners, such as screws, bolts, or pins. The inner tooth portion 110 is connected to the inner side of the first mounting portion 120 and can be integrally formed. Along the axial direction of the wave generator 300, the width of the inner tooth portion 110 is greater than the width of the first mounting portion 120. It is understood that because the width of the inner tooth portion 110 is greater than the width of the first mounting portion 120, a portion of the inner tooth portion 110 protrudes axially from the first mounting portion 120, allowing the inner tooth portion 110 to undergo slight elastic deformation. When the flexspline 200 is subjected to a large load, the slight elastic deformation of the inner tooth portion 110 reduces frictional losses between the flexspline 200 and the rigid pulley 100, thereby increasing the service life of the flexspline 200. At the same time, compared with the rigid wheel in the related art, the width of the inner tooth portion 110 of this embodiment is increased, which can increase the contact area with the outer tooth portion 210, reduce the tooth surface meshing surface pressure, and improve the load-bearing capacity of the harmonic reducer 1000.

[0067] Continue to refer to Figure 4 As shown, in the embodiment of the present invention, the portion of the inner tooth portion 110 that axially protrudes beyond the first mounting portion 120 abuts against the inner side of the inner bearing ring 420. Therefore, the inner bearing ring 420 supports the inner tooth portion 110, preventing the inner tooth portion 110 from being subjected to excessive force and causing large-angle bending deformation, thereby improving the reliability of the rigid wheel 100. A protrusion 421 is provided at one axial end of the inner bearing ring 420. The protrusion 421 protrudes toward the first mounting portion 120, and the inner side of the protrusion 421 abuts against the outer side of the first mounting portion 120. It is understood that the provision of the protrusion 421 serves to position the rigid wheel 100 for installation. Furthermore, the protrusion 421 facilitates the installation of the oil seal 500 between the inner bearing ring 420 and the outer bearing ring 410. The oil seal 500 is annular and concentrically positioned with the outer bearing ring 410. The outer surface of the oil seal 500 forms an interference fit with the inner bore of the outer bearing ring 410, while the inner bore of the oil seal 500 forms a sealing fit with the outer wall of the protrusion 421, enhancing the sealing effect. When the inner bearing ring 420 and the oil seal 500 rotate relative to each other, a radial contact seal is formed, effectively preventing the lubricant in the first and second grooves 430, 440 from escaping into the rigid wheel 100.

[0068] Continue to refer to Figure 4As shown, in the embodiment of the present invention, along the axial direction of the harmonic reducer 1000, the first mounting portion 120 is connected to the end of the inner tooth portion 110 that faces away from the inner bearing ring 420, that is, the first mounting portion 120 is connected to the right end of the inner tooth portion 110. Therefore, the thin-walled design of the inner tooth portion 110 facilitates a certain degree of elastic deformation of the inner tooth portion 110. This can reduce meshing interference without reducing the meshing depth between the inner tooth portion 110 and the outer tooth portion 210, reduce friction loss between the flexspline 200 and the rigid wheel 100, reduce vibration and noise during operation of the harmonic reducer 1000, and increase the service life of the flexspline 200.

[0069] Reference Figure 1 and Figure 2 As shown, in an embodiment of the present invention, along the axial direction of the wave generator 300, the first rolling element 431 is located between the diaphragm 230 and the inner tooth portion 110, which can improve the compactness of the harmonic reducer 1000 and reduce the size of the harmonic reducer 1000. The width of the inner tooth portion 110 is Lc, and the minimum distance between the end surface of the inner tooth portion 110 facing the first rolling element 431 and the center of the second rolling element 441 is L3, satisfying the following: -0.1*Lc≤L3≤0.2*Lc. For example, the value of L3 can be -0.1*Lc, -0.05*Lc, 0.1*Lc, 0.2*Lc, etc. When L3>0, the center of the second rolling element 441 is located between the two axial end surfaces of the outer tooth portion 210. When L3 is less than 0, the center of the second rolling element 441 is located between the outer tooth portion 210 and the diaphragm 230, that is, the center of the second rolling element 441 is located between the end surface of the outer tooth portion 210 facing the diaphragm 230 and the end surface of the diaphragm 230 facing the outer tooth portion 210. It should be noted that the end of the circular spline 100 facing the flange portion 240 is the inner end surface, and the end facing away from the flange portion 240 is the outer end surface. The center of the second rolling element 441 being located between the two axial end surfaces of the outer tooth portion 210 means that the center of the second rolling element 441 is located to the right of the outer end surface of the circular spline 100; the center of the second rolling element 441 being located between the outer tooth portion 210 and the diaphragm 230 means that the center of the second rolling element 441 is located to the left of the outer end surface of the circular spline 100.

[0070] It should also be noted that -0.1*Lc≤L3≤0.2*Lc is equivalent to -0.1≤L3 / Lc≤0.2. Figure 12 As shown, Figure 12The horizontal axis in the figure represents the value of L3 / Lc, the vertical axis on the left represents the weight of the whole harmonic reducer 1000, and the vertical axis on the right represents the vibration acceleration of the harmonic reducer 1000. Vibration acceleration refers to the acceleration caused by vibration phenomena caused by various internal and external factors during the operation of the reducer. The vibration acceleration reflects the stability and smoothness of the reducer during dynamic operation. Smaller vibration acceleration means that the harmonic reducer 1000 is more stable and smooth during operation, which helps to reduce the wear and energy loss of the harmonic reducer 1000 and improve the overall performance and life of the reducer. The weight of the whole machine is the weight of the rigid wheel 100, the flexible wheel 200, the wave generator 300 and the support bearing 400.

[0071] from Figure 12 As can be seen from the figure, as the value of L3 / Lc gradually increases, the weight of the harmonic reducer 1000 remains unchanged and then gradually increases, while the vibration acceleration gradually decreases. Therefore, when designing the harmonic reducer 1000, it is required that the weight of the entire machine is light and the vibration acceleration is small. When the value of L3 / Lc is less than -0.1, although the weight of the entire machine is light, the vibration acceleration is large, and the harmonic reducer 1000 is prone to vibration and noise during operation, and the operating stability is poor. When the value of L3 / Lc is greater than 0.2, although the vibration acceleration is low, the weight of the entire machine increases significantly, and the material cost increases. Therefore, by rationally designing the value of L3 / Lc within the range of -0.1 to 0.2, the weight of the entire machine can be reduced while the vibration acceleration is kept at a lower value, which can reduce production costs while improving the operating stability of the harmonic reducer 1000.

[0072] Reference Figure 5 As shown, in the embodiment of the present invention, the outer tooth portion 210 includes a plurality of convex teeth arranged along the circumference of the flexible wheel 200 and protruding outward, and the plurality of convex teeth include a first tooth segment 211, a second tooth segment 212 and a third tooth segment 213 extending in the axial direction. In the direction from the outer tooth portion 210 to the flange portion 240, that is, Figure 5From right to left in the figure, the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 are connected in sequence. The tooth tip diameter of the first tooth segment 211 gradually decreases in the direction away from the flange portion 240, while the tooth tip diameter of the second tooth segment 212 gradually decreases in the direction toward the flange portion 240. That is, the first tooth segment 211 and the second tooth segment 212 adopt a tooth profile modification scheme, where the tooth height of the first tooth segment 211 and the second tooth segment 212 gradually decreases in the direction away from the third tooth segment 213. Tooth height refers to the height in the radial direction. For example, the tooth tips of the first tooth segment 211 and the second tooth segment 212 can be inclined along a straight line, or can be an outward convex arc, an inward concave arc, etc. By setting the tooth height of the first tooth segment 211 and the second tooth segment 212 to gradually decrease, the interference between the tooth tips of the first tooth segment 211 and the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced, thereby improving the service life of the flexible spline 200.

[0073] Continue to refer to Figure 5 As shown, in the embodiment of the present invention, the diameter of the tooth top circle of the third tooth segment 213 is constant, that is, the tooth height of the third tooth segment 213 remains unchanged. Because the cylindrical portion 220 of the flexible wheel 200 becomes elliptical under the action of the wave generator 300 and has an opening angle, the motion trajectory of the outer tooth portion 210 is different under different cross-sections. The state of the third tooth segment 213 in the middle of the outer tooth portion 210 is optimal and less likely to interfere, while the outer tooth portion 210 is more likely to interfere with the inner tooth portion 110 at both ends along the axial direction. To this end, by designing the tooth height of the first tooth segment 211 and the tooth height of the second tooth segment 212 to gradually decrease in the direction away from the third tooth segment 213, the interference between the tooth tops of the first tooth segment 211 and the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced.

[0074] Reference Figure 2 and Figure 6As shown, in the embodiment of the present invention, along a direction parallel to the rotation axis of the wave generator 300, the effective width of the flexspline 200 is Lf, and the tooth width of the outer tooth portion 210 is Lf1, satisfying the following: 0.4*Lf≤Lf1≤0.6*Lf. For example, the value of Lf1 can be 0.4*Lf, 0.45*Lf, 0.5*Lf, 0.55*Lf, or 0.6*Lf. The width of the first tooth segment 211 is Lf2, satisfying the following: 0.2*Lf1≤Lf2≤0.35*Lf1. For example, the value of Lf2 can be 0.2*Lf1, 0.23*Lf1, 0.24*Lf1, 0.25*Lf1, 0.3*Lf1, or 0.35*Lf1. The width of the third tooth segment 213 is Lf3, which satisfies the following: 0.35*Lf1≤Lf3≤0.45*Lf1. For example, the value of Lf3 can be 0.35*Lf1, 0.38*Lf1, 0.39*Lf1, 0.40*Lf1, 0.42*Lf1, or 0.45*Lf1. The width of the second tooth segment 212 is Lf4, which satisfies the following: 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.

[0075] It is understood that the widths of the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 affect the meshing effect with the inner tooth portion 110. When Lf1 is less than 0.4*Lf, the tooth width of the outer tooth portion 210 is short, the effective meshing area between the outer tooth portion 210 and the inner tooth portion 110 is reduced, and meshing stability deteriorates. When Lf1 is greater than 0.6*Lf, the tooth width of the outer tooth portion 210 is long, increasing the volume of the harmonic accelerator and hindering compact design. When Lf2 is less than 0.2*Lf1, the width of the first tooth segment 211 is small, which can easily interfere with the inner tooth portion 110. When Lf2 is greater than 0.4*Lf1, the width of the first tooth segment 211 is large. While the width of the outer tooth portion 210 remains unchanged, the width of the third tooth segment 213 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the outer tooth portion 210 and the inner tooth portion 110 and deteriorating meshing stability. When Lf3 is less than 0.35*Lf1, meaning the width of the third tooth segment 213 is too small, this also reduces the effective meshing area between the outer tooth portion 210 and the inner tooth portion 110, resulting in poor meshing stability. When Lf3 is greater than 0.45*Lf1, while the width of the outer tooth portion 210 remains unchanged, the widths of the first tooth segment 211 and the second tooth segment 212 must be reduced accordingly, potentially leading to interference with the inner tooth portion 110 at these locations. When Lf4 is less than 0.25*Lf1, meaning the width of the second tooth segment 212 is too small, it can easily interfere with the inner tooth portion 110. When Lf4 is greater than 0.45*Lf1, meaning the width of the second tooth segment 212 is too large, while the width of the outer tooth portion 210 remains unchanged, the width of the third tooth segment 213 must be reduced accordingly, resulting in a reduced effective meshing area between the outer tooth portion 210 and the inner tooth portion 110, resulting in poor meshing stability.

[0076] Therefore, the ratio of the tooth width of the outer tooth portion 210 to the effective width of the flexible spline 200 is reasonably designed to be between 0.4 and 0.6, the ratio of the width of the first tooth segment 211 to the width of the outer tooth portion 210 is between 0.2 and 0.35, the ratio of the width of the third tooth segment 213 to the width of the outer tooth portion 210 is between 0.35 and 0.45, and the ratio of the width of the second tooth segment 212 to the width of the outer tooth portion 210 is between 0.25 and 0.4. While ensuring the meshing stability of the outer tooth portion 210 and the inner tooth portion 110, the interference between the outer tooth portion 210 and the inner tooth portion 110 can be reduced, thereby reducing the friction and wear of the tooth surface, which is beneficial to extending the life of the flexible spline 200.

[0077] Reference Figure 6As shown, in the embodiment of the present invention, the inclination angle of the first tooth segment 211 is α1, and the inclination angle of the second tooth segment is β1. It should be noted that the inclination angle α1 of the first tooth segment 211 refers to: the tooth top of the first tooth segment 211 is configured as a first inclined surface 2111, the first inclined surface 2111 is inclined in a direction away from the third tooth segment 213 and toward the rotation axis, and the angle between the first inclined surface 2111 and the rotation axis is α1. The inclination angle β1 of the second tooth segment refers to: the tooth top of the second tooth segment 212 is configured as a second inclined surface 2112, the second inclined surface 2112 is inclined in a direction away from the third tooth segment 213 and toward the rotation axis, and the angle between the second inclined surface 2112 and the rotation axis is β1.

[0078] The inclination angle α1 of the first tooth segment 211 and the inclination angle β1 of the second tooth segment satisfy the following conditions: 0.3° ≤ α1 ≤ 1°, 0.3° ≤ β1 ≤ 1°, and β1 ≥ α1. For example, the values ​​of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°; and the values ​​of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α1 is less than 0.3°, the inclination angle of the first inclined surface 2111 is too small, making it difficult to reduce interference between the inner and outer teeth 110, 210. When α1 is greater than 1°, the effective meshing area of ​​the first tooth segment 211 and the inner tooth 110 is reduced, resulting in poor meshing stability. When β1 is less than 0.3°, the inclination angle of the second inclined surface 2112 is too small, making it difficult to reduce interference between the inner and outer teeth 110, 210. When β1 is greater than 1°, the effective area of ​​the second tooth segment 212 and the inner tooth portion 110 during meshing is likely to be reduced, thereby causing poor meshing stability.

[0079] It can be understood that when the wave generator 300 is embedded in the inner hole of the cylinder 220, the outer wall of the cylinder 220 will be tilted, that is, an opening angle will be formed. Since the second tooth segment 212 is closer to the flange portion 240 than the first tooth segment 211, the second tooth segment 212 is more likely to interfere with the inner tooth portion 110. Therefore, by setting the inclination angle of the second inclined surface 2112 to be greater than the inclination angle of the first inclined surface 2111, the interference between the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced or avoided, and the contact area between the second tooth segment 212 and the inner tooth portion 110 can be increased to improve the stability during power transmission.

[0080] Continue to refer to Figure 6As shown, in an embodiment of the present invention, in order to further reduce interference between the outer tooth portion 210 and the inner tooth portion 110, a third inclined surface 2121 is provided between two adjacent first tooth segments 211. The third inclined surface 2121 is inclined in a direction away from the third tooth segment 213 and toward the rotation axis. A fourth inclined surface 2122 is provided between two adjacent second tooth segments 212. The fourth inclined surface 2122 is inclined in a direction away from the third tooth segment 213 and toward the rotation axis. The inclination angle of the third inclined surface 2121 and the inclination angle of the first inclined surface 2111 can be the same or different, and the inclination angle of the fourth inclined surface 2122 and the inclination angle of the second inclined surface 2112 can be the same or different. This can effectively reduce or avoid interference between the tooth tops of the inner tooth portion 110 and the tooth roots of the outer tooth portion 210, thereby reducing friction and wear on the tooth surfaces and extending the life of the flexible spline 200.

[0081] Continue to refer to Figure 6 As shown, in the embodiment of the present invention, the inclination angle of the third inclined surface 2121 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°, or 1°. When α2 is less than 0.3°, that is, the inclination angle of the third inclined surface 2121 is too small, it is difficult to reduce the interference between the inner tooth portion 110 and the outer tooth portion 210. When α2 is greater than 1°, it is easy to cause the strength of the outer tooth portion 210 to decrease, and it is easy to cause tearing between adjacent convex teeth. Therefore, a reasonable design of the size of α1 and α2 can effectively reduce the interference between the inner tooth portion 110 and the outer tooth portion 210, improve the service life of the flexible wheel 200, and at the same time ensure that the outer tooth portion 210 has appropriate strength and high reliability.

[0082] Continue to refer to Figure 6 As shown, in an embodiment of the present invention, the inclination angle of the fourth inclined surface 2122 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°, or 1°. When β2 is less than 0.3°, that is, the inclination angle of the fourth inclined surface 2122 is too small, it is difficult to reduce the interference between the inner tooth portion 110 and the outer tooth portion 210. When β2 is greater than 1°, it is easy to cause the strength of the outer tooth portion 210 to decrease, and it is easy to cause tearing between adjacent convex teeth. Therefore, a reasonable design of the size of β1 and β2 can effectively reduce the interference between the inner tooth portion 110 and the outer tooth portion 210, improve the service life of the flexible wheel 200, and at the same time ensure that the outer tooth portion 210 has appropriate strength and high reliability.

[0083] Table 1: Comparison of tooth surface contact area of ​​different schemes

[0084]

[0085] For example, referring to Table 1 above, Solution 1 is a solution from the related art, with Lc = 0.42*Lf, Lf1 = 0.36*Lf, and the tooth height of the outer tooth portion 210 remains unchanged, that is, no tooth profile modification is used. Solution 2 is Lc = 0.55*Lf, Lf1 = 0.5*Lf, and the tooth height of the outer tooth portion 210 remains unchanged, that is, no tooth profile modification is used. Solution 3 is Lc = 0.55*Lf, Lf1 = 0.5*Lf, and the first tooth segment 211 and the second tooth segment 212 of the outer tooth portion 210 adopt a profile modification solution. As can be seen from Table 1 above, the design of Lc = 0.55*Lf and Lf1 = 0.5*Lf can increase the tooth surface contact area by 18.3%. On this basis, adding the profile modification solution increases the improvement by 32.6% compared to Solution 1. The larger the tooth surface contact area, the smaller the contact stress, and the greater the load-bearing capacity of the harmonic reducer 1000.

[0086] Reference Figure 1 and Figure 2 As shown, in the embodiment of the present invention, the effective width of the flexible wheel 200 in the axial direction is Lf, and the effective width of the flexible wheel 200 refers to the minimum distance between the end surface of the end of the cylinder 220 away from the flange portion 240 and the flange portion 240. The maximum distance between the end wall of the outer bearing ring 410 abutting against the end of the flange portion 240 and the center of the first rolling element 431 is L1, which satisfies: 0.2*Lf≤L1≤0.28*Lf. The above formula is equivalent to 0.2≤L1 / Lf≤0.28, for example, the value of L1 / Lf can be 0.2, 0.22, 0.24, 0.26, 0.28, etc. Refer to Figure 13 As shown, Figure 13 The horizontal axis in the figure represents the value of L1 / Lf, the vertical axis on the left represents the allowable torque of the support bearing 400, and the vertical axis on the right represents the weight of the whole harmonic reducer 1000. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use, and the weight of the whole machine is the weight of the rigid wheel 100, the flexible wheel 200, the wave generator 300 and the support bearing 400. Figure 13 As shown, when L1 / Lf is less than 0.2, the overall weight of the harmonic reducer 1000 is relatively light, but the allowable torque decreases rapidly, failing to meet operational requirements. When L1 / Lf is greater than 0.28, the allowable torque is relatively high, but the overall weight increases rapidly, failing to meet operational requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer 1000, setting the L1 / Lf ratio between 0.2 and 0.28 can simultaneously meet the maximum overturning moment requirements and overall weight requirements.

[0087] Reference Figure 1 and Figure 2As shown, in the embodiment of the present invention, the effective width of the flexible wheel 200 along the axial direction is Lf. In the direction parallel to the axial direction, the maximum distance between the center of the first rolling element 431 and the center of the second rolling element 441 is L2, which satisfies: 0.24*Lf≤L2≤0.34*Lf. The above formula is equivalent to 0.24≤L2 / Lf≤0.34. For example, the value of L2 / Lf can be 0.24, 0.25, 0.3, 0.31, or 0.34. Figure 14 As shown, Figure 14 The horizontal axis in the figure represents the value of L2 / Lf, the vertical axis on the left represents the allowable torque of the support bearing 400, and the vertical axis on the right represents the main body length of the harmonic reducer 1000. The main body length is the maximum dimension of the assembly of the rigid wheel 100, the flexible wheel 200 and the support bearing 400 in the axial direction. The definition of the allowable torque is the same as that in the above-mentioned embodiment, and will not be explained in detail when mentioned in the subsequent embodiments. When L2 / Lf is less than 0.24, the main body length of the harmonic reducer 1000 remains basically unchanged, but the allowable torque decreases rapidly and cannot meet the use requirements. When L2 / Lf is greater than 0.34, the allowable torque shows a significant downward trend, and the main body length increases rapidly and cannot meet the use requirements. Therefore, by weighing the requirements of the main body length and the allowable torque of the harmonic reducer 1000, the ratio of L2 / Lf is set between 0.2 and 0.28, which can simultaneously meet the requirements of the maximum overturning moment and the main body length.

[0088] Reference Figure 7 、 Figure 8 and Figure 9 and Figure 10 As shown, in the embodiment of the present invention, the outer bearing ring 410 includes a second mounting portion 411 and a raised portion 412 connected to the inner side of the second mounting portion 411. The raised portion 412 has first and second outer raceways 413 and 414 at opposite ends along the axial direction. The raised portion 412 enhances the structural strength of the first and second outer raceways 413 and 414, effectively reducing their deformation. It also acts as a position limiter for the first and second rolling elements 431 and 441, preventing contact between them. The outer side of the inner bearing ring 420 is provided with a groove 422, located opposite the raised portion 412. The groove 422 has first and second inner raceways 423 and 424 at its axial ends. The first inner raceway 423 and the first outer raceway 413 are arranged opposite each other to form a first groove 430. The second inner raceway 424 and the second outer raceway 414 are arranged opposite each other to form a second groove 440. The above solution is advantageous for installing the first rolling element 431 and the second rolling element 441 , thereby improving assembly efficiency and enabling the first rolling element 431 and the second rolling element 441 to rotate smoothly, thereby improving the stability of the support bearing 400 .

[0089] Reference Figure 4 As shown, in the embodiment of the present invention, a gap is provided between the protrusion 412 and the bottom wall of the groove 422, and the first groove body 430 and the second groove body 440 are connected through the gap. It can be understood that by providing the first groove body 430 and the second groove body 440 with communication through the gap, lubricating oil is facilitated to flow within the first groove body 430 and the second groove body 440, thereby lubricating the first rolling element 431 and the second rolling element 441, thereby improving the smoothness of the rolling of the first rolling element 431 and the service life of the second rolling element 441.

[0090] Reference Figure 4 As shown, in an embodiment of the present invention, the inner bearing ring 420 includes a first ring body 425 and a second ring body 426 connected to each other. The first ring body 425 and the second ring body 426 are arranged in a left-to-right direction and connected by fasteners. A step is provided on the side of the first ring body 425 facing the second ring body 426, and the second ring body 426 is positioned and connected to the step. The step serves as a positioning function, thereby facilitating the connection between the first and second ring bodies 425 and 426. The first inner raceway 423 is located outside the first ring body 425 and adjacent to the second ring body 426. The second inner raceway 424 is located outside the second ring body 426 and away from the first ring body 425. The second ring body 426 is connected to the rigid wheel 100. Designing the inner bearing ring 420 so that the first and second ring bodies 425 and 426 are connected facilitates the installation of the first and second rolling elements 431 and 441, reducing assembly difficulty.

[0091] Reference Figure 8 As shown, in an embodiment of the present invention, within a cross section passing through the rotation axis of the wave generator 300, the outer contour of the first inner raceway 423 is a first curve 4233. The first curve 4233 includes a first arc segment 4231 and a first trimming segment 4232, where the first trimming segment 4232 is a non-circular arc. The radius of the first arc segment 4231 is Ri, and the maximum cross-sectional diameter of the first rolling element 431 is Db1. A coordinate system is established with the center of the first arc segment 4231 as the origin, with the X-axis parallel to the rotation axis and pointing away from the second rolling element 441, and the Y-axis perpendicular to the X-axis and pointing in the direction of the rotation axis. The first curve 4233 satisfies the equation:

[0092] ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi;

[0093] ρi=Ri, when θ1>βi;

[0094] Wherein, Ri=(0.505-0.515)*Db1, ki=0.002-0.004, βi=20°-30°. For example, βi takes values ​​of 20°, 25°, and 30°. It should be noted that θ1 is the central angle of the first curve 4233 relative to the coordinate system point.

[0095] The embodiment of the present invention designs the first curve 4233 so that when the first inner raceway 423 is subjected to a large overturning moment, there is multi-point contact between the first rolling element 431 and the first inner raceway 423, which increases the contact position and contact area and reduces the contact stress. This is significantly better than the single-point contact between the first rolling element 431 and the first inner raceway 423 in the related art (before shaping).

[0096] For example, when the support bearing 400 is subjected to force, both the first rolling element 431 and the first inner raceway 423 will deform. Before reshaping, the first rolling element 431 and the first inner raceway 423 had single-point contact at approximately 40°. However, after reshaping, the first rolling element 431 and the first inner raceway 423 not only contact at approximately 40° but also contact at an angle between 10° and 20°. As a result, the contact area between the first rolling element 431 and the first inner raceway 423 is larger, reducing the contact stress between the first rolling element 431 and the first inner raceway 423, thereby improving the support bearing 400's overall load-bearing capacity, including its overturning moment and overturning moment rigidity.

[0097] Figure 15 This is a comparison diagram of the overturning moment rigidity of the first inner raceway 423 before and after the modification in the harmonic reducer 1000 of an embodiment of the present invention. Figure 15 As shown, after the first inner raceway 423 is modified, when the support bearing 400 is subjected to a large torque (such as Figure 15 (as shown in Figure 1), the angle generated by the overturning moment decreases. According to the equation "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 inner raceway 423 of the present embodiment is modified according to the above equation, the overturning moment rigidity is improved to varying degrees, even by up to 20%.

[0098] It can be understood that in this embodiment, the first inner raceway 423 and the second inner raceway 424 are symmetrical with respect to the center line of symmetry of the first rolling body 431 and the second rolling body 441, and the outer contour line of the second inner raceway 424 is the third curve. The third curve and the first curve 4233 are symmetrical with respect to the center line of symmetry of the first rolling body 431 and the second rolling body 441. Therefore, the equation of the first curve 4233 can be referred to for understanding. In order to avoid repetition, it will not be repeated here.

[0099] Reference Figure 10As shown, in an embodiment of the present invention, within a cross section passing through the rotation axis of the wave generator 300, the outer contour of the first outer raceway 413 is a second curve 4133. The second curve 4133 includes a second arc segment 4131 and a second modified segment 4132, where the second modified segment 4132 is a non-circular arc. The radius of the second arc segment 4131 is Ro, and the maximum cross-sectional diameter of the first rolling element 431 is Db1. A coordinate system is established with the center of the second arc segment 4131 as the origin, with the X-axis parallel to the rotation axis and pointing toward the second rolling element 441, and the Y-axis perpendicular to the X-axis and pointing away from the rotation axis. The second curve 4133 satisfies the equation:

[0100] ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo;

[0101] ρo=Ro, when θ2>βo;

[0102] Wherein, Ro = (0.505-0.515)*Db1, ko = 0.002-0.004, βo = 20°-30°, for example, βo takes values ​​of 20°, 25°, and 30°. It should be noted that θ2 is the central angle of the first curve 4233 relative to the coordinate system point.

[0103] The embodiment of the present invention designs the second curve 4133 so that when the first outer raceway 413 is subjected to a large overturning moment, there is multi-point contact between the first rolling element 431 and the first outer raceway 413, which increases the contact position and contact area and reduces the contact stress. This is significantly better than the single-point contact between the first rolling element 431 and the first outer raceway 413 in the related art (before shaping).

[0104] For example, when the support bearing 400 is subjected to stress, both the first rolling element 431 and the first outer raceway 413 will deform. Before reshaping, the first rolling element 431 and the first outer raceway 413 had single-point contact at approximately 40°. However, after reshaping, the first rolling element 431 and the first outer raceway 413 not only contact at approximately 40° but also contact at an angle between 10° and 20°. As a result, the contact area between the first rolling element 431 and the first outer raceway 413 is larger, reducing the contact stress between the first rolling element 431 and the first outer raceway 413 and improving the support bearing 400's overall load-bearing capacity, including its overturning moment and overturning moment rigidity.

[0105] Figure 15 This is a comparison diagram of the overturning moment rigidity of the first outer raceway 413 before and after the modification in the harmonic reducer 1000 of an embodiment of the present invention. Figure 15 As shown, after the first outer raceway 413 is modified, when the support bearing 400 is subjected to a large torque (such as Figure 15(As shown, when the angle of the overturning moment is greater than 600 N.m, the angle generated by the overturning moment decreases. According to the equation "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 outer raceway 413 of the present embodiment is modified according to the above equation, the overturning moment rigidity is improved to varying degrees, even by up to 20%.

[0106] It can be understood that in this embodiment, the first outer raceway 413 and the second outer raceway 414 are symmetrical with respect to the center line of symmetry of the first rolling body 431 and the second rolling body 441, and the outer contour line of the second outer raceway 414 is the fourth curve. The fourth curve and the second curve 4133 are symmetrical with respect to the center line of symmetry of the first rolling body 431 and the second rolling body 441. Therefore, the equation of the second curve 4133 can be referred to for understanding. In order to avoid repetition, it will not be repeated here.

[0107] Reference Figure 1 As shown, in the embodiment of the present invention, the inner diameter of the flexspline 200 is Df, which is also the inner diameter of the barrel 220. The maximum cross-sectional diameter of the first rolling element 431 is Db1, which satisfies the following: 0.07*Df≤Db1≤0.13*Df. This formula is equivalent to 0.07≤Db1 / Df≤0.13, where Db1 / Df can take values ​​of 0.07, 0.09, 0.1, 0.12, or 0.13. Figure 16 The following is a graph showing the relationship between the ratio of Db1 to Df, the allowable torque of the bearing device, and the overall weight of the harmonic reducer 1000 in one embodiment of the present invention. When Db1 / Df is less than 0.07, the overall weight of the harmonic reducer 1000 remains essentially unchanged, but the allowable torque decreases rapidly, failing to meet usage requirements. When Db1 / Df is greater than 0.13, although the allowable torque continues to increase, the overall weight of the reducer increases rapidly, failing to meet usage requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer 1000, the ratio of Db1 / Df is set within the range of 0.07 to 0.13. The size of the first rolling element 431 is reasonably designed, and the pitch circle distance of the structure formed by the multiple first rolling elements 431 is reasonably designed. While ensuring the compactness of the overall structure, the requirements of the maximum overturning torque and the overall weight of the reducer are met, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing the vibration of the harmonic reducer 1000.

[0108] Continue to refer to Figure 1As shown, in the embodiment of the present invention, the inner diameter of the flexspline 200 is Df. In the direction perpendicular to the axial direction, the diameter of the circle encompassing the centers of the plurality of first rolling elements 431 is Db2, satisfying the following equation: 1.3*Df≤Db2≤1.7*Df. This equation is equivalent to 1.3≤Db2 / Df≤1.7. For example, the value of Db2 / Df can be 1.3, 1.4, 1.5, 1.6, 1.7, and so on. Figure 17 This is a graph showing the relationship between the ratio of Db2 to Df, the allowable torque of the support bearing 400, and the weight of the entire machine in a harmonic reducer 1000 according to an embodiment of the present invention. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. Figure 17 As shown, when Db2 / Df is less than 1.3, the overall weight of the harmonic reducer 1000 is low, but the allowable torque decreases rapidly, failing to meet operational requirements. When Db2 / Df is greater than 1.7, although the allowable torque continues to increase, the overall weight of the reducer rapidly increases, failing to meet operational requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer 1000, setting Db2 / Df between 1.3 and 1.7 can simultaneously meet the maximum overturning moment and overall weight requirements.

[0109] An industrial robot according to one embodiment of the present invention includes a motor and the harmonic reducer 1000 of the above embodiment. It is understood that the motor may be a servo motor, which drives and connects to the harmonic reducer 1000 to control the deceleration of the joints of the industrial robot. The industrial robot may be a handling robot, a welding robot, an assembly robot, a processing robot, a painting robot, a cleaning robot, a collaborative robot, or the like.

[0110] The industrial robot of the present invention employs the harmonic reducer 1000 of the aforementioned embodiment. By positioning the wave generator 300 within the flexspline 200 and partially meshing the outer teeth 210 of the flexspline 200 with the inner teeth 110 of the rigid spline 100, rotation of the wave generator 300 drives relative rotation between the flexspline 200 and the rigid spline 100. A first groove 430 and a second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 of the support bearing 400. The first groove 430 accommodates a first rolling element 431, while the second groove 440 accommodates a second rolling element 441. The first groove 430 and the second groove 440 are spaced apart along the axial direction of the wave generator 300. The provision of two sets of rolling elements effectively enhances the load-bearing capacity of the harmonic reducer 1000, improving the assembly efficiency between the bearing assembly, the rigid spline 100, and the flexspline 200 while maintaining the overall compactness of the structure. At the same time, by setting the ratio of the tooth root wall thickness Tf of the flexspline 200 to the inner hole diameter Df of the flexspline 200 between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the natural logarithmic function Ln(R) is used to eliminate the influence of the reduction ratio R, which is suitable for improving the stress distribution of the harmonic reducer 1000 with different reduction ratios R and reducing the stress on the flexspline 200 during deformation.

[0111] Since the industrial robot of the embodiment of the utility model adopts all the technical solutions of the harmonic reducer 1000 of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here.

[0112] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by 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, including an internal tooth portion; A flexible spline is provided inside the rigid spline, and the flexible spline includes an external tooth portion; a wave generator disposed inside the flexspline and configured to partially mesh the outer tooth portion with the inner tooth portion; a support bearing configured to enable the rigid wheel and the flexible wheel to rotate relative to each other, the support bearing comprising an outer bearing ring and an inner bearing ring disposed within the outer bearing ring, a first groove body for mounting a first rolling element and a second groove body for mounting a second rolling element being disposed between the inner bearing ring and the outer bearing ring, the first groove body and the second groove body being spaced apart along the axial direction of the wave generator; The tooth root wall thickness of the flexspline is Tf, the inner hole diameter of the flexspline is Df, and the reduction ratio of the harmonic reducer is R, which satisfies: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036.

2. The harmonic reducer according to claim 1, characterized in that: Along the axial direction, the effective width of the flexspline is Lf, and the width of the inner tooth portion is Lc, satisfying the following relationship: 0.45*Lf≤Lc≤0.65*Lf.

3. The harmonic reducer according to claim 1, characterized in that: The rigid wheel further includes a first mounting portion connected to the inner bearing ring, the inner tooth portion is connected to the inner side of the first mounting portion, and along the axial direction of the wave generator, the width of the inner tooth portion is greater than the width of the first mounting portion.

4. The harmonic reducer according to claim 3, characterized in that: The portion of the inner tooth portion protruding from the first mounting portion along the axial direction abuts against the inner side of the inner bearing ring; A protrusion protruding toward the first mounting portion is provided at one end of the inner bearing ring along the axial direction, and an inner side of the protrusion abuts against an outer side of the first mounting portion.

5. The harmonic reducer according to claim 3, characterized in that: The first mounting portion is connected to an end of the inner tooth portion that is away from the inner bearing ring along the axial direction.

6. The harmonic reducer according to claim 1, characterized in that: The flexible spline also includes a cylinder, a diaphragm and a flange. The external tooth portion is connected to the outer side of one end of the cylinder, the diaphragm is connected to the other end of the cylinder and extends radially along the cylinder, the flange is connected to the end of the diaphragm away from the cylinder, and the flange is fixedly connected to the outer bearing ring.

7. The harmonic reducer according to claim 6, characterized in that: Along the axial direction of the wave generator, the first rolling element is located between the diaphragm and the inner tooth portion, the width of the inner tooth portion is Lc, and the minimum distance between the end surface of the inner tooth portion facing the first rolling element and the center of the second rolling element is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc, where when L3>0, the center of the second rolling element is located between the two end surfaces of the outer tooth portion along the axial direction, and when L3<0, the center of the second rolling element is located between the outer tooth portion and the diaphragm.

8. The harmonic reducer according to claim 6, characterized in that: Along the axial direction, the external tooth portion includes a first tooth segment away from one end of the flange portion and a second tooth segment close to one end of the flange portion, the diameter of the tooth top circle of the first tooth segment gradually decreases in the direction away from the flange portion, and the diameter of the tooth top circle of the second tooth segment gradually decreases in the direction toward the flange portion.

9. The harmonic reducer according to claim 8, characterized in that: The outer tooth portion further includes a third tooth segment located between the first tooth segment and the second tooth segment, and a diameter of a tooth tip circle of the third tooth segment is constant.

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

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

12. The harmonic reducer according to claim 1 or 2, characterized in that: The flexible spline further includes a cylinder, a diaphragm, and a flange, the external tooth portion being connected to the outer side of one end of the cylinder, the diaphragm being connected to the other end of the cylinder and extending radially along the cylinder, the flange being connected to an end of the diaphragm away from the cylinder, the flange being fixedly connected to the outer bearing ring, the effective width of the flexible spline along the axial direction being Lf, the maximum distance between the end wall of the outer bearing ring abutting against one end of the flange and the center of the first rolling element being L1, and satisfying the following conditions: 0.2*Lf≤L1≤0.28*Lf; and / or, The effective width of the flexible spline along the axial direction is Lf. In a direction parallel to the axial direction, the maximum distance between the center of the first rolling element and the center of the second rolling element is L2, satisfying the following: 0.24*Lf≤L2≤0.34*Lf.

13. The harmonic reducer according to claim 1, characterized in that: The outer bearing ring includes a second mounting portion and a raised portion connected to the inner side of the second mounting portion, and the raised portion is provided with a first outer raceway and a second outer raceway in opposite directions at two ends along the axial direction. The outer side of the inner bearing ring is provided with a groove arranged opposite to the protrusion, and the two ends of the groove along the axial direction are respectively a first inner raceway and a second inner raceway; The first inner raceway and the first outer raceway are arranged opposite to each other and form the first groove body, and the second inner raceway and the second outer raceway are arranged opposite to each other and form the second groove body.

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

15. The harmonic reducer according to claim 13, characterized in that: The inner bearing ring includes a first ring body and a second ring body connected to each other, the first inner raceway is arranged on the outside of the first ring body and close to the second ring body, the second inner raceway is arranged on the outside of the second ring body and away from the first ring body, and the second ring body is connected to the rigid wheel.

16. The harmonic reducer according to claim 13, characterized in that: In a cross section passing through the rotation axis of the wave generator, the outer contour line of the first inner 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; The radius of the first arc segment is Ri, the maximum cross-sectional diameter of the first rolling element is Db1, 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 away from the second rolling element, and the Y-axis is perpendicular to the X-axis and points in the direction of the rotation axis. The first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi=Ri, when θ1>βi; Among them, Ri=(0.505~0.515)*Db1, ki=0.002~0.004, βi=20°-30°.

17. The harmonic reducer according to claim 13, characterized in that: In a cross section passing through the rotation axis of the wave generator, the outer contour line of the first outer raceway 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; The radius of the second arc segment is Ro, the maximum cross-sectional diameter of the first rolling element is Db1, 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 of the second rolling element, and the Y-axis is perpendicular to the X-axis and points away from the rotation axis. The second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; Among them, Ro=(0.505~0.515)*Db1, ko=0.002~0.004, βo=20°-30°.

18. The harmonic reducer according to claim 1, characterized in that: The inner diameter of the flexspline is Df, the maximum cross-sectional diameter of the first rolling element is Db1, and the following conditions are satisfied: 0.07*Df≤Db1≤0.13*Df; and / or, The inner hole diameter of the flexible spline is Df, and the diameter of the circle where the centers of the plurality of first rolling elements are located in a direction perpendicular to the axial direction is Db2, satisfying the following: 1.3*Df≤Db2≤1.7*Df.

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

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