Harmonic reducer and industrial robot

Abstract

The application discloses a kind of harmonic reducer and industrial robot, it is related to the technical field of speed reducer, wherein harmonic reducer includes rigid wheel, flexible wheel, wave generator and support bearing, by setting wave generator is located inside flexible wheel, and make the outer tooth part of flexible wheel and the inner tooth part of rigid wheel partially meshed;First groove body and second groove body are provided between the inner bearing ring and outer bearing ring of support bearing, first groove body is used to install first rolling body, and second groove body is used to install second rolling body. By setting two groups of rolling bodies, the load capacity of harmonic reducer can be effectively improved. At the same time, by setting the ratio of the root wall thickness Tf of flexible wheel and the inner hole diameter Df of flexible wheel between 0.0043Ln (R) -0.0061 and 0.005Ln (R) -0.0036, it is suitable to improve the stress distribution of harmonic reducer with different reduction ratios R, and reduce the stress suffered by flexible wheel when deformed.

Description

Technical Field

[0001] This invention relates to the field of speed reducer technology, and in particular to a harmonic speed reducer and an industrial robot. Background Technology

[0002] In related technologies, harmonic reducers include a wave generator, a flexible wheel, and a rigid wheel. The wave generator is embedded in the inner bore of the flexible wheel, and the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel. When the wave generator rotates, it drives different parts of the outer and inner teeth to mesh, thereby causing relative rotation between the rigid wheel and the flexible wheel, achieving power output. The flexible wheel undergoes reciprocating deformation during operation, and therefore experiences stress. Thus, the design of the flexible wheel needs to minimize the stress generated during deformation. Although flexible wheels of the same specifications have the same inner bore diameter, different reduction ratios result in different numbers of teeth and different modules, leading to different deformations. Therefore, it is difficult to design a suitable structure for the flexible wheel to reduce the magnitude of the stress during deformation. Summary of the Invention

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

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

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

[0006] The harmonic reducer according to embodiments of the present invention has at least the following beneficial effects: By positioning the wave generator inside the flexure and partially meshing the outer teeth of the flexure with the inner teeth of the rigid wheel, the wave generator's rotation drives relative rotation between the flexure and the rigid wheel. A first groove and a second groove are provided between the inner and outer bearing rings of the supporting bearing. The first groove is for mounting the first rolling element, and the second groove is for mounting the second rolling element. These two grooves are spaced apart along the axial direction of the wave generator. The use of two sets of rolling elements effectively enhances the load-bearing capacity of the harmonic reducer, improving assembly efficiency between the bearing assembly and the rigid and flexure wheels while maintaining overall structural compactness. Furthermore, by setting the ratio of the flexure's tooth root wall thickness Tf to its inner diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the stress distribution of harmonic reducers with different reduction ratios R is improved, reducing the stress on the flexure during deformation.

[0007] According to some embodiments of the present invention, along the axial direction, the effective width of the flexible wheel is Lf, and the width of the internal tooth is Lc, satisfying: 0.45*Lf≤Lc≤0.65*Lf.

[0008] According to some embodiments of the present invention, the rigid wheel further includes a first mounting portion connected to the inner bearing ring, the internal tooth portion being connected to the inner side of the first mounting portion, and the width of the internal tooth portion being greater than the width of the first mounting portion along the axial direction of the wave generator.

[0009] According to some embodiments of the present invention, the portion of the internal tooth protruding from the first mounting portion along the axial direction abuts against the inner side of the inner bearing ring; one end of the inner bearing ring along the axial direction is provided with a protrusion protruding toward the first mounting portion, and the inner side of the protrusion abuts against the outer side of the first mounting portion.

[0010] According to some embodiments of the present invention, the first mounting portion is connected to one end of the internal tooth portion that is axially away from the inner bearing ring.

[0011] According to some embodiments of the present invention, the flexible wheel further includes a cylinder portion, a diaphragm portion, and a flange portion, the external tooth portion is connected to the outer side of one end of the cylinder portion, the diaphragm portion is connected to the other end of the cylinder portion and extends radially along the cylinder portion, the flange portion is connected to the end of the diaphragm portion away from the cylinder portion, and the flange portion and the outer bearing ring are fixedly connected.

[0012] 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 internal tooth portion, the width of the internal tooth portion is Lc, and the minimum distance between the end face of the internal tooth portion facing the first rolling element and the center of the second rolling element is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc, where when L3>0, the center of the second rolling element is located between the two end faces of the external tooth portion along the axial direction, and when L3<0, the center of the second rolling element is located between the external tooth portion and the diaphragm.

[0013] According to some embodiments of the present invention, along the axial direction, the external tooth portion includes a first tooth segment away from the flange portion and a second tooth segment near the flange portion, wherein the diameter of the tip circle of the first tooth segment gradually decreases in the direction away from the flange portion, and the diameter of the tip circle of the second tooth segment gradually decreases in the direction toward the flange portion.

[0014] 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, wherein the diameter of the tip circle of the third tooth segment is constant.

[0015] According to some embodiments of the present invention, along the axial direction, the effective width of the flexible wheel is Lf, the width of the external tooth is Lf1, the width of the first tooth segment is Lf2, the width of the second tooth segment is Lf4, and the width of the third tooth segment is Lf3, satisfying: 0.4*Lf≤Lf1≤0.6*Lf; 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

[0016] 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.

[0017] According to some embodiments of the present invention, the flexible wheel further includes a cylindrical portion, a diaphragm portion, and a flange portion. The external toothed portion is connected to the outer side of one end of the cylindrical portion, the diaphragm portion is connected to the other end of the cylindrical portion and extends radially along the cylindrical portion, the flange portion is connected to the end of the diaphragm portion away from the cylindrical portion, the flange portion and the outer bearing ring are fixedly connected, the effective width of the flexible wheel along the axial direction is Lf, the maximum distance between the outer bearing ring abutting the end wall of one end of the flange portion and the center of the first rolling element is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf; and / or, the effective width of the flexible wheel along the axial direction is Lf, and the maximum distance between the center of the first rolling element and the center of the second rolling element in a direction parallel to the axial direction is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf.

[0018] According to some embodiments of the present invention, the outer bearing ring includes a second mounting portion and a protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring has a groove that is disposed opposite to the protrusion. The groove has a first inner raceway and a second inner raceway at both ends along the axial direction. The first inner raceway and the first outer raceway are disposed opposite to each other and form the first groove. The second inner raceway and the second outer raceway are disposed opposite to each other and form the second groove.

[0019] 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 and the second groove are connected through the gap.

[0020] 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 disposed outside the first ring body and close to the second ring body, the second inner raceway is disposed outside the second ring body and away from the first ring body, and the second ring body is connected to the rigid wheel.

[0021] According to some embodiments of the present invention, within a cross-section passing through the rotation axis of the wave generator, the outer contour of the first inner raceway is a first curve, the first curve including a first circular arc segment and a first modified segment, the first modified segment being a non-circular arc; the radius of the first circular arc segment is Ri, the maximum cross-sectional diameter of the first rolling element is Db1, a coordinate system is established with the center of the first circular 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 towards the rotation axis, the first curve satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi=Ri, when θ1>βi; where, Ri=(0.505~0.515)*Db1, ki=0.002~0.004, βi=20°-30°.

[0022] According to some embodiments of the present invention, within the 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 including a second circular arc segment and a second modified segment, the second modified segment being a non-circular arc; the radius of the second circular arc segment is Ro, the maximum cross-sectional diameter of the first rolling element is Db1, a coordinate system is established with the center of the second circular arc segment as the origin, the X-axis is parallel to the rotation axis and points in the direction of the second rolling element, the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis, the second curve satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; where, Ro=(0.505~0.515)*Db1, ko=0.002~0.004, βo=20°-30°.

[0023] According to some embodiments of the present invention, the inner diameter of the flexure is Df, and the maximum cross-sectional diameter of the first rolling element is Db1, satisfying: 0.07*Df≤Db1≤0.13*Df; and / or, the inner diameter of the flexure is Df, and the diameter of the circle containing the centers of the plurality of first rolling elements perpendicular to the axial direction is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df.

[0024] An industrial robot according to a second aspect of the present invention includes the harmonic reducer described in the above embodiments.

[0025] The industrial robot according to embodiments of the present invention has at least the following beneficial effects: The harmonic reducer using the first aspect embodiment has a wave generator located inside the flexure, with the outer teeth of the flexure partially meshing with the inner teeth of the rigid wheel. Therefore, when the wave generator rotates, it can drive the flexure and rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the supporting bearing. The first groove is for mounting a first rolling element, and the second groove is for mounting a second rolling element. The first and second grooves are spaced apart along the axial direction of the wave generator. By providing two sets of rolling elements, the load-bearing capacity of the harmonic reducer can be effectively improved, maintaining the compactness of the overall structure while increasing the assembly efficiency between the bearing assembly and the rigid and flexure wheels. Simultaneously, by setting the ratio of the flexure tooth root wall thickness Tf to the flexure inner diameter Df between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, it is suitable for improving the stress distribution of harmonic reducers with different reduction ratios R and reducing the stress on the flexure during deformation.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic cross-sectional view of a harmonic reducer according to an embodiment of the present invention; Figure 2 This is a partial cross-sectional view of the flexible wheel according to an embodiment of the present invention; Figure 3 This is a partial structural diagram of a flexible wheel according to an embodiment of the present invention; Figure 4 for Figure 1 Enlarged view of point A in the middle; Figure 5 This is a partial cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 6 This is a partial cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the inner bearing ring according to an embodiment of the present invention; Figure 8 for Figure 7 Enlarged view of point B in the middle; Figure 9 This is a cross-sectional view of the outer bearing ring according to an embodiment of the present invention; Figure 10 for Figure 9 Enlarged view of point C in the middle; Figure 11This is a graph showing the relationship between the Tf / Df ratio and the stress at the root of the flexible gear tooth in one embodiment of the present invention. Figure 12 This is a graph showing the relationship between the L3 / Lc ratio and the overall weight and vibration acceleration of an embodiment of the present invention. Figure 13 This is a graph showing the relationship between the L1 / Lf ratio, the allowable torque of the support bearing, and the overall weight of the machine according to an embodiment of the present invention. Figure 14 This is a graph showing the relationship between the L2 / Lf ratio, the allowable torque of the support bearing, and the overall weight of the machine according to an embodiment of the present invention. Figure 15 This is a comparison diagram of the overturning moment stiffness before and after raceway modification in a harmonic reducer according to an embodiment of the present invention. Figure 16 This is a graph showing the relationship between the ratio of Db1 / Df in a harmonic reducer according to an embodiment of the present invention, the allowable torque of the bearing device, and the weight of the whole machine. Figure 17 This is a graph showing the relationship between the ratio of 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.

[0028] Icon labels: Harmonic reducer 1000; 100 steel wheel; 110 internal gear; 120 first mounting part; Flexible gear 200; external tooth section 210; first tooth section 211; first inclined surface 2111; second inclined surface 2112; second tooth section 212; third inclined surface 2121; fourth inclined surface 2122; third tooth section 213; cylindrical section 220; diaphragm section 230; flange section 240; Wave generator 300; Cam 310; Flexible bearing 320; Support bearing 400; outer bearing ring 410; second mounting part 411; protrusion 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 430; first rolling element 431; second groove 440; second rolling element 441; Oil seal 500. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0031] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0032] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0033] Reference Figure 1 and Figure 2 As shown, a harmonic reducer 1000 according to an embodiment of the present invention includes a flexible wheel 200, a rigid wheel 100, and a wave generator 300. The flexible wheel 200 is coaxially mounted inside the rigid wheel 100, and the wave generator 300 is coaxially mounted in the inner hole of the flexible wheel 200. The flexible wheel 200 includes a cylindrical portion 220, a diaphragm portion 230, and a flange portion 240. The cylindrical portion 220 is located at the end of the flexible wheel 200 near the rigid wheel 100. The diaphragm portion 230 is connected to the end of the cylindrical portion 220 away from the rigid wheel 100 and extends radially towards the cylindrical portion 220. The flange portion 240 is connected to the outer periphery of the diaphragm portion 230. The cylindrical portion 220 of the flexible wheel 200 is provided with a flexible external tooth portion 210. The external tooth portion 210 is a structure that bulges outward radially from the cylindrical portion 220. The external tooth portion 210 is not formed in the inner hole of the flexible wheel 200, but is formed on the outer wall of the cylindrical portion 220. The rigid wheel 100 is provided with a rigid internal tooth 110, and an external tooth 210 is engaged with the internal tooth 110, forming a meshing gap between the external tooth 210 and the internal tooth 110.

[0034] In this embodiment of the invention, the wave generator 300 is interference-fitted into the inner bore of the flexible wheel 200. The wave generator 300 is configured to partially mesh with the inner tooth portion 110 when rotating. Partial meshing means that the outer tooth portion 210 of the flexible wheel 200 deforms in the circumferential direction, and the deformed part of the outer tooth portion 210 partially meshes with the corresponding position of the inner tooth portion 110. That is, the meshing position of the inner tooth portion 110 and the outer tooth portion 210 moves cyclically in the circumferential direction. When the wave generator 300 is inserted into the inner bore of the flexible wheel 200, it forces the flexible wheel 200 to undergo elastic deformation and become elliptical. During the operation of the harmonic reducer 1000, the wave generator 300 rotates at high speed, causing the flexible wheel 200 to undergo repeated deformation. This causes the outer tooth 210 of the flexible wheel 200 to mesh with the inner tooth 110 of the rigid wheel 100. The meshing position of the outer tooth 210 and the inner tooth 110 moves circumferentially along the rotation axis of the wave generator 300, thereby achieving relative deceleration between the flexible wheel 200 and the rigid wheel 100. The wave generator 300 includes a flexible bearing 320 and a cam 310. The flexible bearing 320 is sleeved on the outside of the cam 310, and the cam 310 has a mounting position for connecting a motor or other drive device.

[0035] Reference Figure 1 As shown, a harmonic reducer 1000 according to one embodiment of the present invention further includes a support bearing 400, which is configured to allow the rigid wheel 100 and the flexible wheel 200 to rotate relative to each other. The support bearing 400 includes a first rolling element 431, a second rolling element 441, an outer bearing ring 410, and an inner bearing ring 420 disposed within the outer bearing ring 410. An annular first groove 430 and an annular second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 along the axial direction of the wave generator 300. The first groove 430 is located on the side away from the rigid wheel 100, and the second groove 440 is located on the side closer to the rigid wheel 100 and is spaced apart from the first groove 430. That is, the first groove 430 is located on the left side of the harmonic reducer 1000, and the second groove 440 is located on the right side of the harmonic reducer 1000. Multiple first rolling elements 431 are provided and installed in the first groove 430; multiple second rolling elements 441 are provided and installed in the second groove 440. The inner bearing ring 420 is fixedly connected to the rigid wheel 100, and the outer bearing ring 410 is fixedly connected to the flange 240 of the flexible wheel 200. The fixed connection can be achieved through fasteners (such as screws, bolts, pins, etc.), or by snap-fitting, adhesive bonding, or other methods. Therefore, the cooperation of the first rolling elements 431, the second rolling elements 441, the inner bearing ring 420, and the outer bearing ring 410 facilitates the relative rotation of the flexible wheel 200 and the rigid wheel 100.

[0036] By employing two sets of rolling elements, consisting of multiple first rolling elements 431 and multiple second rolling elements 441, the load-bearing capacity of the bearing assembly can be improved compared to the single-row crossed roller bearings in related technologies. Furthermore, the structure of the inner bearing ring 420 and the outer bearing ring 410 facilitates the assembly of the harmonic reducer 1000 and makes it easier to adapt to different loads. It is understood that the first rolling element 431 can be a sphere, or a cylindrical or conical shape; the second rolling element 441 can also be a sphere, or a cylindrical or conical shape, etc., and is not specifically limited here. In addition, in this embodiment, the first rolling elements 431 and the second rolling elements 441 can be made of metal materials such as steel.

[0037] Flexible gears 200 of the same specification have the same inner diameter and basically the same external dimensions. When the reduction ratio of the harmonic reducer 1000 is different, the number of teeth and module of the flexible gear 200 are usually different, resulting in different stresses experienced by the flexible gear 200 during deformation. In order to reduce the stress experienced by the flexible gear 200 during deformation and simplify the design of flexible gears 200 of the same specification but with different reduction ratios, refer to... Figure 1 and Figure 3 As shown, in an embodiment of the present invention, the root wall thickness of the flexible gear 200 is Tf, which refers to the distance between the root of the outer tooth portion 210 and the inner wall of the flexible gear 200 along the radial direction of the flexible gear 200. The inner diameter of the flexible gear 200 is Df, and the reduction ratio of the harmonic reducer 1000 is R, satisfying: 0.0043Ln(R)-0.0061≤Tf / Df≤0.005Ln(R)-0.0036, wherein the reduction ratio R can be obtained from the parameters marked on the nameplate of the harmonic reducer 1000.

[0038] Reference Figure 11 As shown, Figure 11 The graph shows the values ​​of Tf / Df on the horizontal axis and the stress at the tooth root of the flexure 200 on the vertical axis. As the Tf / Df value increases, the tooth root stress on the flexure 200 first decreases and then increases, reaching a minimum value. Therefore, for flexures 200 of the same specification but with different reduction ratios, using the natural logarithm function Ln(R) to eliminate the influence of the reduction ratio R only requires ensuring that the Tf / Df value is limited to the ranges of 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036. This effectively reduces the stress on the flexure 200, simplifies its design, improves production efficiency, and is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R, thus reducing the stress on the flexure 200 during deformation. Meanwhile, compared with the flexible wheel in related technologies, the tooth root wall thickness Tf of the flexible wheel 200 in this embodiment is increased, which can effectively improve the load-bearing capacity and torsional stiffness of the harmonic reducer 1000.

[0039] Reference Figure 2 As shown, in this embodiment of the invention, along the axial direction of the wave generator 300, the effective width of the flexible wheel 200 is Lf, which refers to the minimum distance between the end face of the cylindrical portion 220 away from the flange portion 240 and the flange portion 240. The width of the internal gear portion 110 is Lc, which refers to the maximum length of the internal gear portion 110 along the axial direction, for example, the distance between the two farthest end faces of the rigid wheel 100 along the axial direction. The relationship between Lf and Lc satisfies: 0.45*Lf≤Lc≤0.65*Lf. The value of Lc can be 0.45*Lf, 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, or 0.65*Lf. When Lc is less than 0.45*Lf, meaning the maximum length of the internal gear 110 is short, the contact area between the internal gear 110 and the external gear 210 decreases, increasing contact stress and reducing the load-bearing capacity of the harmonic reducer 1000. When Lc is greater than 0.65*Lf, meaning the maximum length of the internal gear 110 is large, it occupies too much space and has too large a strength margin, which is not conducive to the miniaturization design of the harmonic reducer 1000. Therefore, rationally designing the maximum length Lc and Lf of the internal gear 110 can effectively increase the contact area between the internal gear 110 and the external gear 210, reduce contact stress, improve the load-bearing capacity of the harmonic reducer 1000, and also facilitate the miniaturization design of the harmonic reducer 1000.

[0040] It should be noted that the inner hole of the flexible wheel 200 is circular when it is not installed with the wave generator 300. After the flexible wheel 200 and the wave generator 300 are assembled, the outer tooth 210 of the flexible wheel 200 becomes elliptical. Due to the structural relationship of the flexible wheel 200, the deformation of different sections of the outer tooth 210 along the axial direction is different, and the deformation is greater closer to the opening of the cylinder 220. Generally, the meshing state of the middle tooth section of the outer tooth 210 along the axial direction is optimal. The tooth section near the flange 240 is prone to interference with the tooth tip of the inner tooth 110 of the rigid wheel 100 or the clearance is too small, resulting in abnormal friction and wear and noise. The tooth section away from the flange 240 is prone to interference with the tooth root or middle part of the inner tooth 110 of the rigid wheel 100, which also results in abnormal friction and wear and noise.

[0041] To improve the situation where the external gear 210 easily interferes with the internal gear 110, leading to friction, wear, and noise, refer to Figure 4As shown, in an embodiment of the present invention, the rigid wheel 100 further includes a first mounting portion 120, which is annular and connected to the inner bearing ring 420. The connection between the first mounting portion 120 and the inner bearing ring 420 can be achieved using fasteners, such as screws, bolts, or pins. An internal gear portion 110 is connected to the inner side of the first mounting portion 120, and the connection can be integrally formed. Along the axial direction of the wave generator 300, the width of the internal gear portion 110 is greater than the width of the first mounting portion 120. It is understood that because the width of the internal gear portion 110 is greater than the width of the first mounting portion 120, a portion of the internal gear portion 110 will protrude axially from the first mounting portion 120, allowing the internal gear portion 110 to undergo slight elastic deformation. When the flexible wheel 200 is subjected to a large load, the slight elastic deformation of the internal gear portion 110 reduces frictional loss between the flexible wheel 200 and the rigid wheel 100, thereby improving the service life of the flexible wheel 200. Meanwhile, compared to rigid wheels in related technologies, the width of the internal tooth portion 110 in this embodiment is increased, which can increase the contact area with the external tooth portion 210, reduce the meshing surface pressure of the tooth surface, and improve the load-bearing capacity of the harmonic reducer 1000.

[0042] Continue to refer to Figure 4 As shown, in this embodiment of the invention, the portion of the internal gear 110 that protrudes axially from the first mounting portion 120 abuts against the inner side of the inner bearing ring 420. Therefore, the inner bearing ring 420 supports the internal gear 110, preventing it from being subjected to excessive force and undergoing large-angle bending deformation, thereby improving the reliability of the rigid wheel 100. One end of the inner bearing ring 420 along the axial direction is provided with a protrusion 421, which protrudes towards the first mounting portion 120, and the inner side of the protrusion 421 abuts against the outer side of the first mounting portion 120. It can be understood that the protrusion 421 can serve to position the rigid wheel 100 during installation. Simultaneously, the protrusion 421 also facilitates the installation of the oil seal 500 between the inner bearing ring 420 and the outer bearing ring 410. The oil seal 500 is annular and concentrically positioned with the outer bearing ring 410. The outer side of the oil seal 500 is interference-fitted with the inner hole of the outer bearing ring 410, and the inner hole of the oil seal 500 is sealed with the outer wall of the protrusion 421 to improve the sealing effect. When the inner bearing ring 420 and the oil seal 500 rotate relative to each other, they can also form a radial contact seal, thereby effectively preventing the lubricating material in the first groove 430 and the second groove 440 from overflowing into the rigid wheel 100.

[0043] 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 part 120 is connected to the end of the internal gear part 110 away from the inner bearing ring 420, that is, the first mounting part 120 is connected to the right end of the internal gear part 110. Therefore, the internal gear part 110 is designed with a thin wall, which is beneficial for the internal gear part 110 to generate a certain degree of elastic deformation, which can reduce meshing interference without reducing the meshing depth between the internal gear part 110 and the external gear part 210, reduce the frictional loss between the flexure 200 and the rigid wheel 100, and reduce the vibration and noise of the harmonic reducer 1000 during operation, and improve the service life of the flexure 200.

[0044] Reference Figure 1 and Figure 2 As shown, in this embodiment of the invention, along the axial direction of the wave generator 300, the first rolling element 431 is located between the diaphragm 230 and the internal gear portion 110, which can improve the compactness of the harmonic reducer 1000 and reduce its volume. The width of the internal gear portion 110 is Lc, and the minimum distance between the end face of the internal gear portion 110 facing the first rolling element 431 and the center of the second rolling element 441 is L3, satisfying: -0.1*Lc≤L3≤0.2*Lc. For example, the value of L3 can be -0.1*Lc, -0.05*Lc, 0.1*Lc, 0.2*Lc, etc. When L3>0, the center of the second rolling element 441 is located between the two end faces of the external gear portion 210 along the axial direction. When L3 < 0, the center of the second rolling element 441 is located between the external tooth portion 210 and the diaphragm portion 230, that is, the center of the second rolling element 441 is located between the end face of the external tooth portion 210 facing the diaphragm portion 230 and the end face of the diaphragm portion 230 facing the external tooth portion 210. It should be noted that the end of the rigid wheel 100 facing the flange portion 240 is the inner end face, and the end facing away from the flange portion 240 is the outer end face. "The center of the second rolling element 441 is located between the two axial end faces of the external tooth portion 210" means that the center of the second rolling element 441 is located on the right side of the outer end face of the rigid wheel 100; "The center of the second rolling element 441 is located between the external tooth portion 210 and the diaphragm portion 230" means that the center of the second rolling element 441 is located on the left side of the outer end face of the rigid wheel 100.

[0045] It should also be noted that -0.1*Lc≤L3≤0.2*Lc is equivalent to -0.1≤L3 / Lc≤0.2. (Refer to...) Figure 12 As shown, Figure 12The horizontal axis represents the value of L3 / Lc, the left vertical axis represents the total weight of the harmonic reducer 1000, and the right vertical axis represents the vibration acceleration of the harmonic reducer 1000. Vibration acceleration refers to the acceleration generated by vibration phenomena caused by various internal and external factors during the operation of the reducer. Vibration acceleration reflects the stability and smoothness of the reducer during dynamic operation. A smaller vibration acceleration means that the harmonic reducer 1000 is more stable and smoother during operation, which helps to reduce wear and energy loss, and improve the overall performance and lifespan of the reducer. The total weight includes the weight of the rigid wheel 100, the flexible wheel 200, the wave generator 300, and the support bearing 400.

[0046] from Figure 12 As can be seen, as the value of L3 / Lc gradually increases, the overall weight of the harmonic reducer 1000 initially remains constant and then gradually increases, while the vibration acceleration gradually decreases. Therefore, the design of the harmonic reducer 1000 requires a lightweight overall machine and low vibration acceleration. When the value of L3 / Lc is less than -0.1, although the overall weight is light, the vibration acceleration is relatively large, and the harmonic reducer 1000 is prone to vibration and noise during operation, resulting in poor operational stability. When the value of L3 / Lc is greater than 0.2, although the vibration acceleration is low, the overall weight increases significantly, leading to increased material costs. Therefore, by rationally designing the value of L3 / Lc to be within the range of -0.1 to 0.2, the overall weight can be reduced while keeping the vibration acceleration at a low value, thereby reducing production costs and improving the operational stability of the harmonic reducer 1000.

[0047] Reference Figure 5 As shown, in an embodiment of the present invention, the external toothed portion 210 includes a plurality of protruding teeth arranged circumferentially along the flexible wheel 200 and extending outward. The plurality of protruding teeth includes a first tooth segment 211, a second tooth segment 212, and a third tooth segment 213 extending axially from the external toothed portion 210 to the flange portion 240, i.e. Figure 5From right to left, the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 are connected sequentially. The tip circle diameter of the first tooth segment 211 gradually decreases in the direction away from the flange portion 240, while the tip circle diameter of the second tooth segment 212 gradually decreases in the direction towards the flange portion 240. That is, the first tooth segment 211 and the second tooth segment 212 adopt a tooth-direction modification scheme, and the tooth height of the first tooth segment 211 and the second tooth segment 212 gradually decreases in the direction away from the third tooth segment 213. The tooth height refers to the height in the radial direction. For example, the tip of the first tooth segment 211 and the second tooth segment 212 can be inclined in a straight line, or it can be an outwardly convex arc, an inwardly concave arc, etc. By setting the tooth height of the first tooth segment 211 and the second tooth segment 212 to gradually decrease, the interference between the tip of the first tooth segment 211 and the tip of the second tooth segment 212 and the internal tooth portion 110 can be effectively reduced, thereby improving the service life of the flexible gear 200.

[0048] Continue to refer to Figure 5 As shown, in the embodiment of the present invention, the diameter of the tip circle of the third tooth segment 213 is constant, that is, the tooth height of the third tooth segment 213 remains unchanged. Because the flexible wheel 200, under the action of the wave generator 300, has an elliptical shape after the cylindrical portion 220 becomes elliptical, the motion trajectory of the outer tooth portion 210 at different cross-sections is different. The state is optimal in the middle part of the outer tooth portion 210, that is, the third tooth segment 213, where interference is less likely to occur. However, interference with the inner tooth portion 110 is more likely to occur at both ends of the outer tooth portion 210 along the axial direction. Therefore, by designing the tooth height of the first tooth segment 211 and the tooth height of the second tooth segment 212 to gradually decrease in the direction away from the third tooth segment 213, the interference between the tip of the first tooth segment 211 and the tip of the second tooth segment 212 and the inner tooth portion 110 can be effectively reduced.

[0049] Reference Figure 2 and Figure 6As shown, in an embodiment of the present invention, along a direction parallel to the rotation axis of the wave generator 300, the effective width of the flexible wheel 200 is Lf, and the tooth width of the external tooth portion 210 is Lf1, satisfying: 0.4*Lf≤Lf1≤0.6*Lf. For example, the value of Lf1 can be 0.4*Lf, 0.45*Lf, 0.5*Lf, 0.55*Lf, or 0.6*Lf. The width of the first tooth segment 211 is Lf2, satisfying: 0.2*Lf1≤Lf2≤0.35*Lf1. For example, the value of Lf2 can be 0.2*Lf1, 0.23*Lf1, 0.24*Lf1, 0.25*Lf1, 0.3*Lf1, or 0.35*Lf1. The width of the third tooth segment 213 is Lf3, satisfying: 0.35*Lf1≤Lf3≤0.45*Lf1. For example, the value of Lf3 can be 0.35*Lf1, 0.38*Lf1, 0.39*Lf1, 0.40*Lf1, 0.42*Lf1, or 0.45*Lf1. The width of the second tooth segment 212 is Lf4, satisfying: 0.25*Lf1≤Lf4≤0.4*Lf1. For example, the value of Lf4 can be 0.25*Lf1, 0.28*Lf1, 0.3*Lf1, 0.35*Lf1, 0.38*Lf1, or 0.4*Lf1.

[0050] Understandably, the widths of the first tooth segment 211, the third tooth segment 213, and the second tooth segment 212 affect the meshing effect with the internal tooth portion 110. When Lf1 is less than 0.4*Lf, the tooth width of the external tooth portion 210 is shorter, reducing the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, thus worsening the stability during meshing. When Lf1 is greater than 0.6*Lf, the tooth width of the external tooth portion 210 is longer, increasing the volume of the harmonic accelerator and hindering compact design. When Lf2 is less than 0.2*Lf1, meaning the width of the first tooth segment 211 is smaller, interference with the internal tooth portion 110 is more likely. When Lf2 is greater than 0.4*Lf1, meaning the width of the first tooth segment 211 is larger, the width of the third tooth segment 213 needs to be shortened accordingly while keeping the width of the external tooth portion 210 constant, resulting in a reduction in the effective meshing area between the external tooth portion 210 and the internal tooth portion 110, further worsening the stability during meshing. When Lf3 is less than 0.35*Lf1, meaning the width of the third tooth segment 213 is small, the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110 will decrease, resulting in poorer stability during meshing. When Lf3 is greater than 0.45*Lf1, with the width of the external tooth portion 210 remaining constant, the widths of the first tooth segment 211 and the second tooth segment 212 need to be reduced accordingly, which can easily lead to interference with the internal tooth portion 110 at the first tooth segment 211 and the second tooth segment 212. When Lf4 is less than 0.25*Lf1, meaning the width of the second tooth segment 212 is small, it is easy to interfere with the internal tooth portion 110. When Lf4 is greater than 0.45*Lf1, meaning the width of the second tooth segment 212 is large, with the width of the external tooth portion 210 remaining constant, the width of the third tooth segment 213 needs to be shortened accordingly, resulting in a decrease in the effective meshing area of ​​the external tooth portion 210 and the internal tooth portion 110, and worsening stability during meshing.

[0051] Therefore, by rationally designing the ratio of the tooth width of the external tooth section 210 to the effective width of the flexible gear 200 to be between 0.4 and 0.6, the ratio of the width of the first tooth segment 211 to the width of the external tooth section 210 to be between 0.2 and 0.35, the ratio of the width of the third tooth segment 213 to the width of the external tooth section 210 to be between 0.35 and 0.45, and the ratio of the width of the second tooth segment 212 to the width of the external tooth section 210 to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the external tooth section 210 and the internal tooth section 110, while also reducing the interference between the external tooth section 210 and the internal tooth section 110, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear 200.

[0052] 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 fact that the tooth tip of the first tooth segment 211 is constructed as a first inclined surface 2111, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle α1 between the first inclined surface 2111 and the rotation axis. The inclination angle β1 of the second tooth segment refers to the fact that the tooth tip of the second tooth segment 212 is constructed as a second inclined surface 2112, which is inclined in a direction away from the third tooth segment 213 and towards the rotation axis, with an angle β1 between the second inclined surface 2112 and the rotation axis.

[0053] The inclination angle α1 of the first tooth segment 211 and the inclination angle β1 of the second tooth segment satisfy the following conditions: 0.3°≤α1≤1°, 0.3°≤β1≤1°, and β1≥α1. For example, the value of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°; and the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α1 is less than 0.3°, that is, the inclination angle of the first inclined surface 2111 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α1 is greater than 1°, it is easy to reduce the effective area when the first tooth segment 211 and the internal tooth portion 110 mesh, thus leading to a decrease in meshing stability. When β1 is less than 0.3°, that is, the inclination angle of the second inclined surface 2112 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β1 is greater than 1°, it can easily lead to a reduction in the effective area when the second tooth segment 212 and the internal tooth portion 110 mesh, thereby resulting in poor meshing stability.

[0054] It is understandable that when the wave generator 300 is embedded in the inner hole of the cylindrical part 220, the outer wall of the cylindrical part 220 will be tilted, i.e., an angle will be formed. Since the second tooth segment 212 is closer to the flange part 240 than the first tooth segment 211, the second tooth segment 212 is more likely to interfere with the inner tooth part 110. Therefore, by setting the inclination angle of the second inclined surface 2112 to be greater than the inclination angle of the first inclined surface 2111, the interference between the second tooth segment 212 and the inner tooth part 110 can be effectively reduced or avoided, and the contact area between the second tooth segment 212 and the inner tooth part 110 can be increased to improve the stability during power transmission.

[0055] Continue to refer to Figure 6As shown in the embodiment of the present invention, in order to further reduce the interference between the external tooth portion 210 and the internal tooth portion 110, a third inclined surface 2121 is provided between two adjacent first tooth segments 211. The third inclined surface 2121 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. A fourth inclined surface 2122 is provided between two adjacent second tooth segments 212. The fourth inclined surface 2122 is inclined in a direction away from the third tooth segment 213 and towards the rotation axis. The inclination angle of the third inclined surface 2121 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 effectively reduces or avoids the interference between the tooth tip of the internal tooth portion 110 and the tooth root of the external tooth portion 210, thereby reducing the friction and wear of the tooth surface and extending the life of the flexible gear 200.

[0056] Continue to refer to Figure 6 As shown, in an embodiment of the present invention, the inclination angle of the third inclined surface 2121 is α2, satisfying: 0.3°≤α2≤1°. For example, the value of α2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α2 is less than 0.3°, that is, the inclination angle of the third inclined surface 2121 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When α2 is greater than 1°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent protrusions. Therefore, by reasonably designing the sizes of α1 and α2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0057] 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, satisfying: 0.3°≤β2≤1°. For example, the value of β2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When β2 is less than 0.3°, that is, the inclination angle of the fourth inclined surface 2122 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β2 is greater than 1°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent protrusions. Therefore, by reasonably designing the sizes of β1 and β2, the interference between the internal tooth portion 110 and the external tooth portion 210 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 210 can be guaranteed to have appropriate strength and high reliability.

[0058] Table 1: Comparison of tooth surface contact area under different schemes

[0059] For example, referring to Table 1 above, Scheme 1 is a scheme in the related art, where Lc = 0.42 * Lf, Lf1 = 0.36 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 2 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the tooth height of the external tooth portion 210 remains unchanged, i.e., no tooth profile modification is used; Scheme 3 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the first tooth segment 211 and the second tooth segment 212 of the external tooth portion 210 adopt a modification scheme. As can be seen from Table 1 above, designing Lc = 0.55 * Lf and Lf1 = 0.5 * Lf can increase the tooth surface contact area by 18.3%, and further adding a modification scheme on this basis increases the improvement by 32.6% compared to Scheme 1. The larger the contact area of ​​the tooth surface, the smaller the contact stress, and the greater the load-bearing capacity of the harmonic reducer 1000.

[0060] Reference Figure 1 and Figure 2 As shown, in an embodiment of the present invention, the effective width of the flexible wheel 200 along the axial direction is Lf. The effective width of the flexible wheel 200 refers to the minimum distance between the end face of the cylindrical portion 220 away from the flange portion 240 and the flange portion 240. The maximum distance between the outer bearing ring 410 abutting against the end wall of one end of the flange portion 240 and the center of the first rolling element 431 is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf. Wherein, 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 represents the value of L1 / Lf, the left vertical axis represents the allowable torque of the support bearing 400, and the right vertical axis represents the total weight of the harmonic reducer 1000. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand under normal use, and the total weight includes the weight of the rigid wheel 100, the flexible wheel 200, the wave generator 300, and the support bearing 400. (Refer to...) 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 the usage requirements. When L1 / Lf is greater than 0.28, the allowable torque is larger, but the overall weight increases rapidly, also failing to meet the usage requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer 1000, setting the L1 / Lf ratio between 0.2 and 0.28 can simultaneously meet the requirements for maximum overturning moment and overall weight.

[0061] Reference Figure 1 and Figure 2As shown, in an embodiment of the present invention, the effective width of the flexible wheel 200 along the axial direction is Lf, and the maximum distance between the center of the first rolling element 431 and the center of the second rolling element 441 parallel to the axial direction is L2, satisfying: 0.24*Lf≤L2≤0.34*Lf. Wherein, 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. (Refer to...) Figure 14 As shown, Figure 14 The horizontal axis in the diagram represents the value of L2 / Lf, the left vertical axis represents the allowable torque of the support bearing 400, and the right vertical axis represents the main body length of the harmonic reducer 1000. The main body length is the maximum axial dimension of the assembly of the rigid wheel 100, flexible wheel 200, and support bearing 400. The definition of allowable torque is the same as in the above embodiment, and will not be explained in detail in subsequent embodiments. When L2 / Lf is less than 0.24, the main body length of the harmonic reducer 1000 remains basically unchanged, but the allowable torque decreases rapidly, which cannot meet the usage requirements. When L2 / Lf is greater than 0.34, the allowable torque shows a significant downward trend, and the main body length increases rapidly, which also cannot meet the usage requirements. Therefore, by balancing the requirements of the main body length and 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.

[0062] Reference Figure 7 , Figure 8 and Figure 9 and Figure 10 As shown, in an embodiment of the present invention, the outer bearing ring 410 includes a second mounting portion 411 and a protrusion 412 connected to the inner side of the second mounting portion 411. The protrusion 412 has a first outer raceway 413 and a second outer raceway 414 respectively at its two axial ends. The protrusion 412 enhances the structural strength of the first outer raceway 413 and the second outer raceway 414, effectively reducing deformation, and also limits the movement of the first rolling element 431 and the second rolling element 441, preventing them from contacting each other. The outer side of the inner bearing ring 420 has a groove 422 opposite to the protrusion 412. The two axial ends of the groove 422 are a first inner raceway 423 and a second inner raceway 424. The first inner raceway 423 and the first outer raceway 413 are opposite to each other and form a first groove 430, while the second inner raceway 424 and the second outer raceway 414 are opposite to each other and form a second groove 440. The above scheme facilitates the installation of the first rolling element 431 and the second rolling element 441, improves assembly efficiency, and enables the first rolling element 431 and the second rolling element 441 to rotate smoothly, thereby improving the stability of the support bearing 400 during operation.

[0063] Reference Figure 4 As shown, in an embodiment of the present invention, there is a gap between the bottom wall of the protrusion 412 and the groove 422, and the first groove 430 and the second groove 440 are connected through the gap. It is understood that by providing a gap connecting the first groove 430 and the second groove 440, lubricating oil can flow within the first groove 430 and the second groove 440, thereby lubricating the first rolling element 431 and the second rolling element 441, improving the smoothness and service life of the first rolling element 431 and the second rolling element 441 during rolling.

[0064] 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 together. The first ring body 425 and the second ring body 426 are arranged from left to right and are connected by fasteners. A step is provided on the side of the first ring body 425 facing the second ring body 426, and the second ring body 426 is positioned and connected to the step. The step serves a positioning function, thereby facilitating the connection between the first ring body 425 and the second ring body 426. A first inner raceway 423 is located outside the first ring body 425 and close to the second ring body 426, and a second inner raceway 424 is located outside the second ring body 426 and away from the first ring body 425. The second ring body 426 is connected to the rigid wheel 100. By designing the inner bearing ring 420 with the first ring body 425 and the second ring body 426 connected, the installation of the first rolling element 431 and the second rolling element 441 is facilitated, reducing assembly difficulty.

[0065] Reference Figure 8 As shown in the embodiment of the present invention, within the cross-section passing through the rotation axis of the wave generator 300, the outer contour line of the first inner raceway 423 is a first curve 4233. The first curve 4233 includes a first circular arc segment 4231 and a first shaping segment 4232, the first shaping segment 4232 being a non-circular arc. The radius of the first circular arc segment 4231 is Ri, and the maximum cross-sectional diameter of the first rolling element 431 is Db1. A coordinate system is established with the center of the first circular arc segment 4231 as the origin. The X-axis is parallel to the rotation axis and points away from the direction of the second rolling element 441, and the Y-axis is perpendicular to the X-axis and points towards the rotation axis. The first curve 4233 satisfies the equation: ρi=Ri+ki*Ri*[sin(90°*θ1 / βi)-1], when 0°≤θ1≤βi; ρi=Ri, when θ1>βi; Where Ri = (0.505~0.515)*Db1, ki = 0.002~0.004, βi = 20°-30°, for example, βi takes values ​​of 20°, 25°, and 30°. It should be noted that θ1 is the central angle of the first curve 4233 relative to the center point of the coordinate system.

[0066] In this embodiment of the invention, the design of the first curve 4233 is such 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, reduces the contact stress, and is significantly better than the single-point contact between the first rolling element 431 and the first inner raceway 423 in the related art (before modification).

[0067] For example, when the support bearing 400 is under stress, both the first rolling element 431 and the first inner raceway 423 deform. Before the deformation, the first rolling element 431 and the first inner raceway 423 have a single-point contact at approximately 40°; however, after the deformation, the first rolling element 431 and the first inner raceway 423 not only have contact at approximately 40°, but also have contact between 10° and 20°. Therefore, the contact area between the first rolling element 431 and the first inner raceway 423 is larger, which can reduce the contact stress between the first rolling element 431 and the first inner raceway 423, thereby improving the overall overturning moment and overturning moment rigidity of the support bearing 400.

[0068] Figure 15 This is a comparison diagram of the overturning moment stiffness of the first inner raceway 423 before and after modification in a harmonic reducer 1000 according to an embodiment of the present invention. (Refer to...) 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 (greater than Nm), the angle at which the overturning moment is generated becomes smaller; according to the formula overturning moment stiffness = overturning moment / angle at which the overturning moment is generated, when the overturning moment is constant, the smaller the angle at which the overturning moment is generated, the greater the overturning moment stiffness. Therefore, after the first inner raceway 423 of this embodiment of the invention is modified by the above equation, the overturning moment stiffness is improved to varying degrees, even up to 20%.

[0069] It is understood that in this embodiment, the first inner raceway 423 and the second inner raceway 424 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. The outer contour of the second inner raceway 424 is the third curve. The third curve and the first curve 4233 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. Therefore, the equation of the first curve 4233 can be used for understanding. To avoid repetition, it will not be described again here.

[0070] Reference Figure 10As shown in the embodiment of the present invention, within the cross-section passing through the rotation axis of the wave generator 300, the outer contour line of the first outer raceway 413 is a second curve 4133. The second curve 4133 includes a second arc segment 4131 and a second shaping segment 4132, where the second shaping segment 4132 is 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. The X-axis is parallel to the rotation axis and points in the direction of the second rolling element 441, and the Y-axis is perpendicular to the X-axis and points in the direction away from the rotation axis. The second curve 4133 satisfies the equation: ρo=Ro+ko*Ro*[sin(90°*θ2 / βo)-1], when 0°≤θ2≤βo; ρo=Ro, when θ2>βo; Where Ro = (0.505~0.515)*Db1, ko = 0.002~0.004, βo = 20°-30°, for example, βo can take values ​​of 20°, 25°, and 30°. It should be noted that θ2 is the central angle of the first curve 4233 relative to the center point of the coordinate system.

[0071] The present invention designs the second curve 4133 so that when the first outer raceway 413 is subjected to a large overturning moment, the first rolling element 431 and the first outer raceway 413 have multi-point contact, which increases the contact position and contact area, reduces the contact stress, and is significantly better than the single-point contact between the first rolling element 431 and the first outer raceway 413 in the related technology (before modification).

[0072] For example, when the support bearing 400 is under stress, both the first rolling element 431 and the first outer raceway 413 deform. Before the deformation, the first rolling element 431 and the first outer raceway 413 have a single-point contact at approximately 40°; however, after the deformation, the first rolling element 431 and the first outer raceway 413 not only have contact at approximately 40°, but also have contact between 10° and 20°. Therefore, the contact area between the first rolling element 431 and the first outer raceway 413 is larger, which can reduce the contact stress between the first rolling element 431 and the first outer raceway 413, thereby improving the overall overturning moment and overturning moment rigidity of the support bearing 400.

[0073] Figure 15 This is a comparison diagram of the overturning moment stiffness of the first outer raceway 413 before and after modification in a harmonic reducer 1000 according to an embodiment of the present invention. (Refer to...) 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, greater than 600 N·m), the angle at which the overturning moment is generated becomes smaller; according to the formula overturning moment stiffness = overturning moment / angle at which the overturning moment is generated, when the overturning moment is constant, the smaller the angle at which the overturning moment is generated, the greater the overturning moment stiffness. Therefore, after the first outer raceway 413 of this embodiment of the invention is modified by the above equation, the overturning moment stiffness is improved to varying degrees, even up to 20%.

[0074] It is understood that in this embodiment, the first outer raceway 413 and the second outer raceway 414 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. The outer contour of the second outer raceway 414 is the fourth curve. The fourth curve and the second curve 4133 are symmetrical with respect to the center line of symmetry of the first rolling element 431 and the second rolling element 441. Therefore, the equation of the second curve 4133 can be used for understanding. To avoid repetition, it will not be described again here.

[0075] Reference Figure 1 As shown, in this embodiment of the invention, the inner diameter of the flexible wheel 200 is Df, which is also the inner diameter of the cylindrical portion 220. The maximum cross-sectional diameter of the first rolling element 431 is Db1, satisfying: 0.07*Df≤Db1≤0.13*Df. This formula is equivalent to 0.07≤Db1 / Df≤0.13, where the value of Db1 / Df can be 0.07, 0.09, 0.1, 0.12, or 0.13. Figure 16 This diagram illustrates the relationship between the ratio of Db1 to Df in a harmonic reducer 1000 according to an embodiment of the present invention, the allowable torque of the bearing assembly, and the overall weight. 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 increases rapidly, also 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 also reasonably designed. This ensures the compactness of the overall structure while meeting the requirements for maximum overturning moment and overall weight, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing its vibration.

[0076] Continue to refer to Figure 1As shown, in an embodiment of the present invention, the inner diameter of the flexible wheel 200 is Df. The diameter of the circle containing the centers of the plurality of first rolling elements 431 perpendicular to the axial direction is Db2, satisfying: 1.3*Df≤Db2≤1.7*Df. This formula is equivalent to 1.3≤Db2 / Df≤1.7, for example, the value of Db2 / Df can be 1.3, 1.4, 1.5, 1.6, 1.7, etc. Figure 17 This diagram illustrates the relationship between the ratio of Db2 to Df in a harmonic reducer 1000 according to an embodiment of the present invention, the allowable torque of the support bearing 400, and the overall weight. It should be noted that the allowable torque is the maximum overturning torque that the support bearing 400 can withstand during normal use. (Refer to...) Figure 17 As shown, when Db2 / Df is less than 1.3, the overall weight of the harmonic reducer 1000 is relatively small, but the allowable torque decreases rapidly, failing to meet the usage requirements. When Db2 / Df is greater than 1.7, although the allowable torque continues to increase, the overall weight increases rapidly, also failing to meet the usage requirements. Therefore, by balancing the overall weight and allowable torque requirements of the harmonic reducer 1000, setting the value of Db2 / Df between 1.3 and 1.7 can simultaneously meet the requirements of the maximum overturning moment and the overall weight requirements.

[0077] An embodiment of the present invention provides an industrial robot comprising a motor and a harmonic reducer 1000 as described in the above embodiment. It is understood that the motor can be a servo motor, which drives the harmonic reducer 1000 for speed reduction control of the industrial robot's joints. The industrial robot can be a handling robot, welding robot, assembly robot, processing robot, painting robot, cleanroom robot, collaborative robot, etc.

[0078] The industrial robot of this embodiment uses the harmonic reducer 1000 described above. By positioning the wave generator 300 inside the flexible wheel 200, and ensuring that the outer teeth 210 of the flexible wheel 200 partially mesh with the inner teeth 110 of the rigid wheel 100, the wave generator 300 can drive the flexible wheel 200 and the rigid wheel 100 to rotate relative to each other. A first groove 430 and a second groove 440 are provided between the inner bearing ring 420 and the outer bearing ring 410 of the support bearing 400. The first groove 430 is used to install the first rolling element 431, and the second groove 440 is used to install the second rolling element 441. The first groove 430 and the second groove 440 are spaced apart along the axial direction of the wave generator 300. By providing two sets of rolling elements, the load-bearing capacity of the harmonic reducer 1000 can be effectively improved, and the assembly efficiency between the bearing assembly, the rigid wheel 100, and the flexible wheel 200 can be improved while maintaining the overall structural compactness. Meanwhile, by setting the ratio of the tooth root wall thickness Tf of the flexible wheel 200 to the inner diameter Df of the flexible wheel 200 to between 0.0043Ln(R)-0.0061 and 0.005Ln(R)-0.0036, the influence of the reduction ratio R is eliminated by using the natural logarithmic function Ln(R). This is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R and reducing the stress on the flexible wheel 200 during deformation.

[0079] The industrial robot of this invention adopts all the technical solutions of the harmonic reducer 1000 of the above embodiments, and therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0080] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

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

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

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

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

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

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

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

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

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

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

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

12. The harmonic reducer according to claim 1 or 2, characterized in that: The flexible wheel further includes a cylindrical portion, a diaphragm portion, and a flange portion. The external toothed portion is connected to the outer side of one end of the cylindrical portion. The diaphragm portion is connected to the other end of the cylindrical portion and extends radially along the cylindrical portion. The flange portion is connected to the end of the diaphragm portion away from the cylindrical portion. The flange portion and the outer bearing ring are fixedly connected. The effective width of the flexible wheel along the axial direction is Lf. The maximum distance between the outer bearing ring abutting against the end wall of one end of the flange portion and the center of the first rolling element is L1, satisfying: 0.2*Lf≤L1≤0.28*Lf; and / or, The effective width of the flexible wheel along the axial direction is Lf, and the maximum distance between the center of the first rolling element and the center of the second rolling element in the direction parallel to the axial direction is L2, satisfying: 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 protrusion connected to the inner side of the second mounting portion. The protrusion has a first outer raceway and a second outer raceway that are opposite to each other at both ends along the axial direction. The outer side of the inner bearing ring is provided with a groove opposite to the protrusion, and the two ends of the groove along the axial direction are the first inner raceway and the second inner raceway, respectively. The first inner raceway and the first outer raceway are arranged opposite each other to form the first groove, and the second inner raceway and the second outer raceway are arranged opposite each other to form the second groove.

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

15. The harmonic reducer according to claim 13, 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 located outside the first ring body and close to the second ring body, and the second inner raceway is located outside the second ring body and away from the first ring body. The second ring body is connected to the rigid wheel.

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

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

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

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

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