Harmonic speed reducer and industrial robot

Abstract

The invention discloses a harmonic speed reducer and an industrial robot, and relates to the technical field of speed reducers, the harmonic speed reducer comprises a rigid gear, a flexible gear and a wave generator, the wave generator is coaxially mounted in an inner hole of the flexible gear, and an outer tooth part of the flexible gear is meshed with an inner tooth part of the rigid gear. The outer tooth portion is arranged on a cylinder portion of the flexible gear, a convex tooth of the outer tooth portion comprises a first shape correction section, a middle section and a second shape correction section which are sequentially connected, the tooth height of the first shape correction section and the tooth height of the second shape correction section are gradually reduced in the direction away from the middle section, and the ratio of the width of the first shape correction section to the width of the convex tooth is designed to range from 0.2 to 0.35. And the ratio of the width of the middle section to the width of the convex teeth is 0.35-0.45, and the ratio of the width of the second modification section to the width of the convex teeth is 0.25-0.4, so that the meshing stability of the convex teeth and the inner tooth part can be ensured, the interference between the convex teeth and the inner tooth part can be reduced, the frictional wear of the tooth surface can be reduced, and the service life of the flexible gear can be prolonged.

Description

TECHNICAL FIELD

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

[0002] In the related art, the harmonic reducer comprises a wave generator, a flexspline and a rigid gear, the flexspline is sleeved on the wave generator, and the outer tooth part of the flexspline and the inner tooth part of the rigid gear are in meshing. The flexspline is elastically deformed under the action of the wave generator, and the tooth profile shape and position of the deformed flexspline will change. If the deformation amount of the flexspline is too large or the deformation is uneven, it may cause interference between the outer tooth part of the flexspline and the inner tooth part of the rigid gear during meshing. It is easy to cause severe wear between the inner tooth part and the outer tooth part, resulting in the phenomenon of tooth jumping and slipping, and shortening the service life of the harmonic reducer. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a harmonic reducer, which can reduce the interference between the outer tooth part of the flexspline and the inner tooth part of the rigid gear, so as to improve the service life of the harmonic reducer.

[0004] The present application also provides an industrial robot with the above harmonic reducer.

[0005] According to the harmonic reducer of the first aspect of the present application, the harmonic reducer comprises: a rigid gear provided with an inner tooth part; a flexspline comprising a barrel part, a diaphragm part and a flange part, the barrel part being provided with an outer tooth part matched with the inner tooth part, the outer tooth part being coaxially installed in the inner tooth part, the diaphragm part being connected to one end of the barrel part away from the outer tooth part and extending outwardly of the barrel part, and the flange part being connected to the outer circumferential edge of the diaphragm part; a wave generator coaxially installed in the inner hole of the flexspline, the wave generator being configured to mesh the outer tooth part with the inner tooth part when rotating; wherein the outer tooth part comprises a convex tooth arranged around the circumference of the barrel part, and from the outer tooth part to the flange part, the convex tooth comprises a first modified segment, an intermediate segment and a second modified segment connected in sequence, the tooth height of the first modified segment and the tooth height of the second modified segment gradually decrease in the direction away from the intermediate segment, and in the direction parallel to the rotation axis of the wave generator, the tooth width of the convex tooth is Lf1, the width of the first modified segment is Lf2, the width of the intermediate segment is Lf3, and the width of the second modified segment is Lf4, and the following conditions are met: 0.2*Lf1≤Lf2≤0.35*Lf1; 0.35*Lf1≤Lf3≤0.45*Lf1; 0.25*Lf1≤Lf4≤0.4*Lf1.

[0006] The harmonic reducer according to embodiments of the present invention has at least the following beneficial effects: By coaxially mounting the wave generator within the inner bore of the flexible wheel, the outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel. Therefore, when the wave generator rotates, it drives the flexible wheel and the rigid wheel to rotate relative to each other. The outer teeth are located in the cylindrical portion of the flexible wheel, which is also connected to a diaphragm, which in turn is connected to a flange. The outer teeth include convex teeth. Since interference with the inner teeth is likely to occur at both ends of the convex teeth along the axial direction, the convex teeth are designed to include a first modified section, an intermediate section, and a second modified section connected in sequence. The tooth height of the first modified section and the tooth height of the second modified section gradually decrease in the direction away from the intermediate section, effectively reducing interference between the convex teeth and the inner teeth. Meanwhile, by rationally designing the ratio of the width of the first shaping section to the width of the convex tooth to be between 0.2 and 0.35, the ratio of the width of the middle section to the width of the convex tooth to be between 0.35 and 0.45, and the ratio of the width of the second shaping section to the width of the convex tooth to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the convex tooth and the internal tooth, while also reducing the interference between the convex tooth and the internal tooth, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear.

[0007] According to some embodiments of the present invention, the tooth tip of the first modified segment is configured as a first inclined surface that is inclined in a direction away from the intermediate segment and toward the axis of rotation, and the tooth tip of the second modified segment is configured as a second inclined surface that is inclined in a direction away from the intermediate segment and toward the axis of rotation, wherein the inclination angle of the second inclined surface is greater than the inclination angle of the first inclined surface.

[0008] According to some embodiments of the present invention, the tooth tip of the first modified segment is configured as a first inclined surface that is inclined in a direction away from the intermediate segment and toward the axis of rotation, the inclination angle of the first inclined surface being α1, satisfying: 0.3°≤α1≤1°.

[0009] According to some embodiments of the present invention, the tooth tip of the second modified segment is configured as a second inclined surface that is inclined in a direction away from the intermediate segment and toward the axis of rotation, the inclination angle of the second inclined surface being β1, satisfying: 0.3°≤β1≤1°, and β1≥α1.

[0010] According to some embodiments of the present invention, the minimum distance between the end wall of the cylindrical portion away from the flange portion and the flange portion is Lf, and the maximum length of the internal tooth portion along the rotation axis is Lc, satisfying: 0.5*Lf≤Lc≤0.6*Lf.

[0011] According to some embodiments of the present invention, the minimum distance between the end wall of the cylindrical portion away from the flange portion and the flange portion is Lf, which satisfies: 0.45*Lf≤Lf1≤0.55*Lf.

[0012] According to some embodiments of the present invention, one end of the second shaping section facing the flange portion is connected to the cylindrical portion via an arc-shaped section.

[0013] According to some embodiments of the present invention, the connection between the diaphragm and the cylindrical portion is constructed as a corner portion, the inner side and the outer side of the corner portion are respectively constructed as a first arc segment and a second arc segment, the outer side of the diaphragm portion is constructed as a first segment, the inner side of the diaphragm portion is constructed as a first curved segment and a second segment, the two ends of the first curved segment are respectively connected to the inner side of the flange portion and the second segment, the first curved segment is composed of at least two arc segments, one of the first segment and the second segment is a first straight segment, and the other is a second curved segment, the second curved segment is composed of at least one arc segment.

[0014] According to some embodiments of the present invention, the connection between the diaphragm and the cylindrical portion is constructed as a corner portion. The cylindrical portion includes a first cylindrical segment and a second cylindrical segment connected together. The external toothed portion is disposed on the first cylindrical segment. The inner side of the second cylindrical segment is constructed as a third segment, and the outer side of the second cylindrical segment is constructed as a fourth segment. One of the third segment and the fourth segment is a second straight segment, and the other is a third straight segment and a third curved segment connected together. The third curved segment is closer to the corner portion than the third straight segment, and the third curved segment is composed of at least two arc segments.

[0015] According to some embodiments of the present invention, the effective length of the diaphragm is Lf5, and the radial distances from points a, b, d, and e of the diaphragm to one end of the diaphragm connected to the flange are defined as La, Lb, Ld, and Le, respectively, wherein: La = 0.02 * Lf5; Lb = 0.1 * Lf5; Ld = 0.45 * Lf5; Le = 0.86 * Lf5; The wall thicknesses of the diaphragm at points a, b, d, and e are ta, tb, td, and te, respectively. The connection between the diaphragm and the cylindrical section is constructed as a corner section, and the maximum wall thickness of the corner section is to; It satisfies: td < tb < te ≤ to < ta ≤ 2 * td.

[0016] According to some embodiments of the present invention, the minimum distance between the end wall of the cylindrical portion away from the flange portion and the flange portion is Lf, and the axial distances from points g, h, i, j, k, and m of the cylindrical portion to the outer side wall of the flange portion are defined as Lg, Lh, Li, Lj, Lk, and Lm, respectively, wherein: Lg = 0.04 * Lf; Lh = 0.10 * Lf; Li = 0.20 * Lf; Lj = 0.30 * Lf; Lk = 0.40 * Lf; Lm = 0.45 * Lf; The wall thicknesses of the cylindrical sections at points g, h, i, j, k, and m are respectively: tg, th, ti, tj, tk, and tm. The connection between the diaphragm and the cylindrical section is constructed as a corner section, and the maximum wall thickness of the corner section is to; Satisfies: th≤tg<ti≤to<tj≤tk<tm.

[0017] An industrial robot according to a second aspect of the present invention includes the harmonic reducer described in the above embodiments.

[0018] 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 coaxially mounted in the inner hole of a flexible wheel. The outer teeth of the flexible wheel mesh with the inner teeth of the rigid wheel, so that the rotation of the wave generator can drive the flexible wheel and the rigid wheel to rotate relative to each other. The outer teeth are located in the cylindrical part of the flexible wheel, which is also connected to a diaphragm, which is connected to a flange. The outer teeth include convex teeth. Since interference with the inner teeth is likely to occur at both ends of the convex teeth along the axial direction, the convex teeth are provided with a first modified section, an intermediate section, and a second modified section connected in sequence. The tooth height of the first modified section and the tooth height of the second modified section gradually decrease in the direction away from the intermediate section, which can effectively reduce the interference between the convex teeth and the inner teeth. Meanwhile, by rationally designing the ratio of the width of the first shaping section to the width of the convex tooth to be between 0.2 and 0.35, the ratio of the width of the middle section to the width of the convex tooth to be between 0.35 and 0.45, and the ratio of the width of the second shaping section to the width of the convex tooth to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the convex tooth and the internal tooth, while also reducing the interference between the convex tooth and the internal tooth, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear.

[0019] 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

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a cross-sectional schematic diagram of a harmonic reducer according to an embodiment of the present invention; Figure 2This is a partial structural cross-sectional view of the flexible wheel and rigid wheel in one embodiment of the present invention; Figure 3 This is a partial structural cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 4 This is a partial structural cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 5 for Figure 2 Enlarged view of point A in the middle; Figure 6 This is a cross-sectional view of the diaphragm according to another embodiment of the present invention; Figure 7 This is a partial structural cross-sectional view of a flexible wheel 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 partial structural cross-sectional view of the second cylindrical portion according to another embodiment of the present invention.

[0021] Icon labels: Harmonic reducer 1000; Rigid wheel 100; internal gear 110; Flexible wheel 200; cylindrical section 210; first cylindrical section 211; second cylindrical section 212; third section 2121; fourth section 2122; second straight section 2123; third curved section 2124; third straight section 2125; diaphragm 220; first section 221; first straight section 2211; second section 222; second curved section 2221; first curved section 223; flange 230; external toothed section 240; protruding tooth 241; first modified section 242; first inclined surface 2421; third inclined surface 2422; middle section 243; second modified section 244; second inclined surface 2441; fourth inclined surface 2442; corner section 250; first arc section 251; second arc section 252; arc section 260; Wave generator 300; Cam 310; Flexible bearing 320; Support bearing 400. Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Reference Figure 1 and Figure 2 As shown, a harmonic reducer 1000 according to an embodiment of the present invention can be used in a robot to achieve motor speed reduction. The harmonic reducer 1000 includes a rigid wheel 100, a flexible wheel 200, a wave generator 300, and a support bearing 400. The rigid wheel 100 is annular and has an internal toothed portion 110 on its inner sidewall, which is arranged circumferentially around the rigid wheel 100. The flexible wheel 200 includes a cylindrical portion 210, a diaphragm portion 220, and a flange portion 230. The cylindrical portion 210 is cylindrical, and an external toothed portion 240 that mates with the internal toothed portion 110 is provided on the outer sidewall of one end of the cylindrical portion 210. The external toothed portion 240 is coaxially mounted within the internal toothed portion 110. The diaphragm portion 220 is connected to the end of the cylindrical portion 210 away from the external toothed portion 240 and extends along the outer side of the cylindrical portion 210. Extending along the outer side of the cylindrical portion 210 means extending in a direction away from the rotation axis of the harmonic reducer 1000. The flange 230 is annular, and its inner wall is connected to the outer periphery of the diaphragm 220. The flange 230 is used to connect with the support bearing 400. The wave generator 300 is coaxially mounted in the inner hole of the flexible wheel 200. The wave generator 300 includes a cam 310 and a flexible bearing 320. The flexible bearing 320 is sleeved on the outer wall of the cam 310, so the flexible bearing 320 can deform under the action of the cam 310. When the cam 310 rotates under the drive of the motor, it drives the inner ring of the flexible bearing 320 to rotate synchronously, causing the outer ring shape of the flexible bearing 320 to change repeatedly, thereby making the external tooth 240 and the internal tooth 110 mesh.

[0027] Reference Figure 3 As shown, the external toothed portion 240 includes circumferentially arranged protruding teeth 241 surrounding the cylindrical portion 210, in the direction from the external toothed portion 240 to the flange portion 230, i.e.Figure 3 From right to left, the tooth 241 includes a first modified section 242, a middle section 243, and a second modified section 244 connected in sequence. The tooth height of the first modified section 242 and the tooth height of the second modified section 244 gradually decrease in the direction away from the middle section 243. The tooth height refers to the height in the radial direction. For example, the tooth tip of the first modified section 242 and the second modified section 244 can be inclined in a straight line, or be an outwardly convex arc, an inwardly concave arc, etc.

[0028] Along the rotation axis parallel to the wave generator 300, the tooth width of the protruding tooth 241 is Lf1, and the width of the first shaping section 242 is Lf2, satisfying: 0.2*Lf1≤Lf2≤0.35*Lf1. For example, the value of Lf2 can be 0.2*Lf1, 0.23*Lf1, 0.24*Lf1, 0.25*Lf1, 0.3*Lf1, or 0.35*Lf1. The width of the middle section 243 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 shaping segment 244 is Lf4, which satisfies: 0.25*Lf1≤Lf4≤0.4*Lf1. For example, the value of Lf4 can be 0.25*Lf1, 0.28*Lf1, 0.3*Lf1, 0.35*Lf1, 0.38*Lf1, or 0.4*Lf1.

[0029] Understandably, because the flexible wheel 200, under the action of the wave generator 300, transforms the cylindrical portion 210 into an elliptical shape, resulting in an angle, the motion trajectory of the outer tooth portion 240 differs at different interfaces. The optimal state is found in the middle section 243 of the convex tooth 241, where interference is less likely to occur. However, interference with the inner tooth portion 110 is more likely to occur at the two ends of the convex tooth 241 along the axial direction. Therefore, by designing the tooth height of the first modified section 242 and the second modified section 244 to gradually decrease in the direction away from the middle section 243, the interference between the tooth tip of the first modified section 242 and the tooth tip of the second modified section 244 and the inner tooth portion 110 can be effectively reduced.

[0030] The widths of the first modified section 242, the intermediate section 243, and the second modified section 244 affect the meshing effect with the internal tooth portion 110. When Lf2 is less than 0.2*Lf1, meaning the width of the first modified section 242 is small, it is prone to interference with the internal tooth portion 110. When Lf2 is greater than 0.4*Lf1, meaning the width of the first modified section 242 is large, while the width of the convex tooth 241 remains unchanged, the width of the intermediate section 243 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the external tooth portion 240 and the internal tooth portion 110, and a decrease in meshing stability. When Lf3 is less than 0.35*Lf1, meaning the width of the intermediate section 243 is small, it also leads to a reduction in the effective meshing area between the external tooth portion 240 and the internal tooth portion 110, and a decrease in meshing stability. When Lf3 is greater than 0.45*Lf1, with the width of the protruding tooth 241 remaining constant, the widths of the first modified section 242 and the second modified section 244 need to be reduced accordingly, which easily leads to interference with the internal tooth portion 110 at the first modified section 242 and the second modified section 244. When Lf4 is less than 0.25*Lf1, that is, the width of the second modified section 244 is small, which easily leads to interference with the internal tooth portion 110. When Lf4 is greater than 0.45*Lf1, that is, the width of the second modified section 244 is large, with the width of the protruding tooth 241 remaining constant, the width of the intermediate section 243 needs to be shortened accordingly, resulting in a reduction in the effective meshing area between the external tooth portion 240 and the internal tooth portion 110, and a decrease in the stability during meshing.

[0031] Therefore, by rationally designing the width ratio of the first modified section 242 to the width of the tooth 241 to be between 0.2 and 0.35, the width ratio of the middle section 243 to the width of the tooth 241 to be between 0.35 and 0.45, and the width ratio of the second modified section 244 to the width of the tooth 241 to be between 0.25 and 0.4, it is possible to ensure the meshing stability of the tooth 241 and the internal tooth 110, while also reducing the interference between the external tooth 240 and the internal tooth 110, thereby reducing the friction and wear of the tooth surface and helping to extend the life of the flexible gear 200.

[0032] Reference Figure 4As shown, in an embodiment of the present invention, the tooth tip of the first modified section 242 is constructed as a first inclined surface 2421, which is inclined in a direction away from the intermediate section 243 and towards the rotation axis. The tooth tip of the second modified section 244 is constructed as a second inclined surface 2441, which is inclined in a direction away from the intermediate section 243 and towards the rotation axis. The inclination angle of the second inclined surface 2441 is greater than that of the first inclined surface 2421. It should be noted that the inclination angle of the first inclined surface 2421 refers to the angle α1 between the first inclined surface 2421 and the rotation axis, and the inclination angle of the second inclined surface 2441 refers to the angle β1 between the second inclined surface 2441 and the rotation axis. It is understandable that when the wave generator 300 is embedded in the inner hole of the cylindrical part 210, the outer wall of the cylindrical part 210 will be tilted, forming an angle. Since the second modified section 244 is closer to the flange part 230 than the first modified section 242, the second modified section 244 is more likely to interfere with the internal tooth part 110. Therefore, by setting the inclination angle of the second inclined surface 2441 to be greater than the inclination angle of the first inclined surface 2421, the interference between the second modified section 244 and the internal tooth part 110 can be effectively reduced or avoided, and the contact area between the second modified section 244 and the internal tooth part 110 can be increased to improve the stability during power transmission.

[0033] Continue to refer to Figure 4 As shown in the embodiment of the present invention, in order to further reduce the interference between the external tooth portion 240 and the internal tooth portion 110, a third inclined surface 2422 is provided between two adjacent first modified sections 242. The third inclined surface 2422 is inclined in a direction away from the middle section 243 and towards the rotation axis. A fourth inclined surface 2442 is provided between two adjacent second modified sections 244. The fourth inclined surface 2442 is inclined in a direction away from the middle section 243 and towards the rotation axis. The inclination angle of the third inclined surface 2422 and the inclination angle of the first inclined surface 2421 can be the same or different, and the inclination angle of the fourth inclined surface 2442 and the inclination angle of the second inclined surface 2441 can be the same or different. This can effectively reduce or avoid the interference between the tooth tip of the internal tooth portion 110 and the tooth root of the external tooth portion 240, thereby reducing the friction and wear of the tooth surface and extending the life of the flexible gear 200.

[0034] Continue to refer to Figure 4As shown, in an embodiment of the present invention, the inclination angle of the first inclined surface 2421 is α1, satisfying: 0.3°≤α1≤1°. For example, the value of α1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α1 is less than 0.3°, that is, the inclination angle of the first inclined surface 2421 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 240. When α1 is greater than 1°, it is easy to reduce the effective area when the first modified section 242 and the internal tooth portion 110 mesh, thereby resulting in poor meshing stability. The inclination angle of the third inclined surface 2422 is α2, satisfying: 0.3°≤α2≤1°. For example, the value of α2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When α2 is less than 0.3°, meaning the inclination angle of the third inclined plane 2422 is too small, it is difficult to reduce interference between the internal tooth portion 110 and the external tooth portion 240. When α2 is greater than 1°, it can easily lead to a decrease in the strength of the external tooth portion 240, and tearing can easily occur between adjacent protruding teeth 241. Therefore, by rationally designing the sizes of α1 and α2, interference between the internal tooth portion 110 and the external tooth portion 240 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 240 can be guaranteed to have appropriate strength and high reliability.

[0035] Continue to refer to Figure 4 As shown, in an embodiment of the present invention, the inclination angle of the second inclined surface 2441 is β1, satisfying: 0.3°≤β1≤1°. For example, the value of β1 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When β1 is less than 0.3°, that is, the inclination angle of the second inclined surface 2441 is too small, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 240. When β1 is greater than 1°, it is easy to reduce the effective area when the second modified section 244 and the internal tooth portion 110 mesh, thereby resulting in poor meshing stability. The inclination angle of the fourth inclined surface 2442 is β2, satisfying: 0.3°≤β2≤1°. For example, the value of β2 can be 0.3°, 0.4°, 0.6°, 0.7°, 0.9°, or 1°. When β2 is less than 0.3°, meaning the inclination angle of the fourth inclined surface 2442 is too small, it is difficult to reduce interference between the internal tooth portion 110 and the external tooth portion 240. When β2 is greater than 1°, it can easily lead to a decrease in the strength of the external tooth portion 240, and tearing can easily occur between adjacent protruding teeth 241. Therefore, by rationally designing the sizes of β1 and β2, interference between the internal tooth portion 110 and the external tooth portion 240 can be effectively reduced, the service life of the flexible gear 200 can be improved, and the external tooth portion 240 can be guaranteed to have appropriate strength and high reliability.

[0036] Wherein, β1≥α1. It is understandable that, since the second modified section 244 is closer to the flange portion 230 than the first modified section 242, the second modified section 244 is more likely to interfere with the internal gear portion 110. Therefore, by setting the inclination angle of the second inclined surface 2441 to be greater than the inclination angle of the first inclined surface 2421, the interference between the second modified section 244 and the internal gear portion 110 can be effectively reduced or avoided, and the contact area between the second modified section 244 and the internal gear portion 110 can be increased to improve the stability during power transmission.

[0037] Reference Figure 2 As shown in the embodiment of the present invention, the minimum distance between the end wall of the cylindrical portion 210 away from the flange portion 230 and the flange portion 230 is Lf, and the maximum length of the internal gear portion 110 along the axis of rotation is Lc, satisfying: 0.5*Lf≤Lc≤0.6*Lf, where the value of Lc can be 0.5*Lf, 0.51*Lf, 0.53*Lf, 0.55*Lf, 0.58*Lf, or 0.6*Lf. When Lc is less than 0.5*Lf, that is, the maximum length of the internal gear portion 110 is short, the contact area between the tooth surfaces of the internal gear portion 110 and the external gear portion 240 is reduced, the contact stress is increased, and the load-bearing capacity of the harmonic reducer 1000 is reduced. When Lc is greater than 0.6*Lf, that is, the maximum length of the internal gear portion 110 is large, the space occupied is too large, the strength margin is too large, which is not conducive to the miniaturization design of the harmonic reducer 1000. Therefore, by rationally designing the maximum lengths Lc and Lf of the internal gear 110, the contact area between the internal gear 110 and the external gear 240 can be effectively increased, the contact stress reduced, and the load-bearing capacity of the harmonic reducer 1000 improved. At the same time, it is also conducive to the miniaturization design of the harmonic reducer 1000.

[0038] Continue to refer to Figure 2As shown, in an embodiment of the present invention, the minimum distance between the end wall of the cylindrical portion 210 away from the flange portion 230 and the flange portion 230 is Lf. Along a direction parallel to the rotation axis of the wave generator 300, the tooth width of the protruding tooth 241 is Lf1, satisfying: 0.45*Lf≤Lf1≤0.55*Lf. For example, the value of Lf1 can be 0.45*Lf, 0.46*Lf, 0.48*Lf, 0.5*Lf, 0.51*Lf, or 0.55*Lf. When Lf1 is less than 0.45*Lf, that is, the tooth width of the protruding tooth 241 is small, the contact area between the inner tooth portion 110 and the outer tooth portion 240 decreases, the contact stress increases, and the load-bearing capacity of the harmonic reducer 1000 decreases. When Lf1 is greater than 0.6*Lf, the tooth width of the convex tooth 241 is relatively large, occupying more space, which is not conducive to the flexible deformation of the cylinder 210, resulting in a reduction in the deformation capacity of the flexure 200. Therefore, by rationally designing the ratio of Lf1 to Lf, the contact area between the tooth surfaces of the internal tooth 110 and the external tooth 240 can be increased, the contact stress can be reduced, the load-bearing capacity of the harmonic reducer 1000 can be improved, and at the same time, the flexure 200 can be ensured to have a suitable deformation capacity.

[0039] Reference Figure 2 As shown, in the embodiment of the present invention, the tooth width Lf1 of the convex tooth 241 is less than the maximum length Lc of the internal tooth portion 110. It is understood that the flexure 200 experiences axial movement during operation, and due to machining errors, if the tooth width Lf1 of the convex tooth 241 is greater than the maximum length Lc of the internal tooth portion 110, a portion of the convex tooth 241 may not be in a meshing state, affecting the stability of the meshing. Since the harmonic reducer 1000 primarily verifies the stability of the flexure 200, designing the tooth width Lf1 of the convex tooth 241 to be less than the maximum length Lc of the internal tooth portion 110 improves the stability and reliability of the flexure 200's meshing.

[0040] Table 1: Comparison of tooth surface contact area under different schemes

[0041] 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 protruding tooth 241 remains unchanged, i.e., no tooth profile modification is used; Scheme 2 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the tooth height of the protruding tooth 241 remains unchanged, i.e., no tooth profile modification is used; Scheme 3 is where Lc = 0.55 * Lf, Lf1 = 0.5 * Lf, and the protruding tooth 241 has a modification scheme with a first modification segment 242 and a second modification segment 244. 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 modification schemes 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.

[0042] Continue to refer to Figure 2 As shown, in an embodiment of the present invention, the end of the second modified section 244 facing the flange portion 230 and the cylindrical portion 210 are transitionally connected by an arc-shaped section 260, which can be a circular arc segment. It is understood that using the arc-shaped section 260 for transition connection can reduce stress concentration at the connection between the external tooth portion 240 and the cylindrical portion 210. During gear transmission, this design can distribute the load, reduce stress concentration, and make the stress distribution more uniform, thereby improving the overall strength and durability of the flexible gear 200. It also simplifies the machining process of the flexible gear 200 and improves production efficiency.

[0043] Reference Figure 5As shown, in an embodiment of the present invention, the connection between the diaphragm 220 and the cylindrical portion 210 is constructed as a corner portion 250. The inner side of the corner portion 250 is constructed as a first arc segment 251, and the outer side of the corner portion 250 is constructed as a second arc segment 252, thereby facilitating the processing and manufacturing of the flexible wheel 200 and improving production efficiency. The outer side of the diaphragm 220 is constructed as a first segment 221, and the inner side of the diaphragm 220 is constructed as a second segment 222 and a first curved segment 223. It should be noted that the outer side of the diaphragm 220 refers to the side of the diaphragm 220 facing the external tooth portion 240, and the inner side of the diaphragm 220 refers to the side of the diaphragm 220 away from the external tooth portion 240. The two ends of the first curved segment 223 are respectively connected to the inner side of the flange portion 230 and the second segment 222, and the first curved segment 223 is composed of at least two arc segments, thereby facilitating the connection between the diaphragm 220 and the flange portion 230 and reducing stress concentration, thereby improving the reliability and stability of the connection. In this design, the first segment 221 is a straight segment 2211, and the second segment 222 is a curved segment 2221, which is recessed towards the first straight segment 2211. Therefore, along the direction away from the rotation axis, the thickness of the diaphragm 220 gradually decreases and then gradually increases, reducing the stiffness of the diaphragm 220 at the second curved segment 2221. This facilitates the deformation of the diaphragm 220, effectively reducing stress concentration at both ends of the diaphragm 220 in the radial direction, lowering the risk of breakage, and improving the reliability and service life of the flexible wheel 200.

[0044] Reference Figure 6 As shown, in another embodiment of the present invention, the first segment 221 is the second curved segment 2221, and the second segment 222 is the first straight segment 2211. Along the direction away from the axis of rotation, the thickness of the diaphragm 220 can also gradually decrease and then gradually increase, thereby effectively reducing the stress at both ends of the diaphragm 220 in the radial direction, and simultaneously facilitating the deformation of the diaphragm 220, thus improving the service life of the flexible wheel 200. A suitable solution should be selected based on the actual situation.

[0045] Reference Figure 7 and Figure 8As shown, in another embodiment of the present invention, the cylindrical portion 210 includes a first cylindrical section 211 and a second cylindrical section 212 connected together. The first cylindrical section 211 is connected to the end of the second cylindrical section 212 away from the flange portion 230. The second cylindrical section 212 is connected to the corner portion 250, and an external toothed portion 240 is provided on the outer side wall of the first cylindrical section 211. The inner side of the second cylindrical section 212 is constructed as a third section 2121, which consists of a third straight section 2125 and a third curved section 2124 connected together. The third curved section 2124 is recessed toward the fourth section 2122. The outer side of the second cylindrical section 212 is constructed as a fourth section 2122, which consists of a second straight section 2123. The third curved section 2124 is closer to the corner portion 250 than the third straight section 2125, and the third curved section 2124 is composed of at least two arc segments, which can reduce stress concentration. Understandably, driven by the wave generator 300, the cylindrical portion 210 of the flexible wheel 200 will repeatedly deform, resulting in higher stress at the connection point with the corner portion 250. Therefore, by setting the third curved segment 2124 near the corner portion 250, the thickness of the second cylindrical segment 212 at the third curved segment 2124 can be reduced, which is beneficial for the deformation of the cylindrical portion 210 and thus reduces stress.

[0046] Reference Figure 9 As shown, in another embodiment of the present invention, the third segment 2121 is the second straight segment 2123, and the fourth segment 2122 is the connected third straight segment 2125 and third curved segment 2124. The third curved segment 2124 is recessed towards the fourth segment 2122, and is closer to the corner 250 than the third straight segment 2125. By positioning the third curved segment 2124 near the corner 250, the thickness of the second cylindrical segment 212 at the third curved segment 2124 can be reduced, which is beneficial for the deformation of the cylindrical segment 210 and thus reduces stress.

[0047] Reference Figure 5 As shown, in the embodiment of the present invention, the effective length of the diaphragm 220 is Lf5, which refers to the shortest distance between the inner wall of the diaphragm 220 and the inner wall of the flange 230. The radial distances from points a, b, d, and e of the diaphragm 220 to one end of the diaphragm 220 connected to the flange 230 are defined as La, Lb, Ld, and Le, respectively, where: La = 0.02 * Lf5; Lb = 0.1 * Lf5; Ld = 0.45 * Lf5; Le = 0.86 * Lf5; the wall thicknesses of the diaphragm 220 at points a, b, d, and e are ta, tb, td, and te, respectively; the maximum wall thickness of the corner portion 250 is to, satisfying: td < tb < te ≤ to < ta ≤ 2 * td, that is, the diaphragm 220 is thicker at both ends and thinner in the middle along the radial direction.

[0048] Understandably, point d is roughly located in the middle of the diaphragm 220, where the thickness is relatively thin. This reduces the stiffness of the diaphragm 220 at this location, which is beneficial for its deformation. It effectively reduces stress concentration at both ends of the diaphragm 220 along the radial direction, lowering the risk of fracture and improving the reliability and service life of the flexible wheel 200. When td is less than tb, te, to, and ta, the stress at points a and o is significantly reduced. When tb is less than te and to is less than ta, the stress at points a and o is further reduced, improving the reliability of the diaphragm 220. Point a is relatively close to the flange 230. To ensure the stability and reliability of the connection between the diaphragm 220 and the flange 230, the design is ta ≥ to > te > tb > td. When ta > 2 * td, the stress at point d will increase significantly; therefore, the design needs to be ta ≤ 2 * td to reduce the stress at point d.

[0049] Table 2: Comparison of stress values ​​for different schemes

[0050] It should be noted that the solutions in Table 2 are for cases where the thickness of the diaphragm 220 is uniform. In this solution, td < tb < te ≤ to < ta ≤ 2*td. As can be seen from Table 2, after adopting the solution of this embodiment, the stress at points a, b, d, e, and o is reduced, which can improve the reliability and stability of the flexible wheel 200 and extend its service life.

[0051] Reference Figure 7 As shown in the embodiment of the present invention, the minimum distance between the end wall of the cylinder 210 away from the flange 230 and the flange 230 is Lf. The axial distances from points g, h, i, j, k, and m of the cylinder 210 to the outer side wall of the flange 230 are defined as Lg, Lh, Li, Lj, Lk, and Lm, respectively. It should be noted that the outer side wall of the flange 230 refers to the side of the flange 230 facing the external toothed portion 240. Where: Lg=0.04*Lf; Lh=0.10*Lf; Li=0.20*Lf; Lj=0.30*Lf; Lk=0.40*Lf; Lm=0.45*Lf; the wall thicknesses of the diaphragm 220 at points g, h, i, j, k, and m are tg, th, ti, tj, tk, and tm, respectively; the maximum wall thickness of the corner 250 is to; satisfying: th≤tg<ti≤to<tj≤tk<tm.

[0052] It is understandable that the wall thickness of the cylindrical part 210 from point o to point m is designed to be thicker at both ends and thinner in the middle, i.e. th≤(tg,ti)≤(to,tj), which reduces the rigidity of the cylindrical part 210 and reduces the stress at point o. When tg<ti and to<tj are designed, the stress at point o can be further reduced. When tj≤tk<tm is designed, it is beneficial to reduce the stress on the external tooth part 240.

[0053] Table 3: Comparison of stress values ​​for different schemes

[0054] It should be noted that the solutions in Table 3 are for cases where the thickness of the cylinder 210 is uniform. In this solution, th ≤ tg < ti ≤ to < tj ≤ tk < tm. As can be seen from Table 3, after adopting the solution of this embodiment, the stress at points o, g, h, i, j, k, and m is reduced, which improves the reliability and stability of the cylinder 210 and extends its service life.

[0055] This invention discloses an industrial robot according to one embodiment. The industrial robot can be a welding robot, a handling robot, a painting robot, a processing robot, or an assembly robot. The industrial robot employs the harmonic reducer described in the above embodiment. A wave generator 300 is coaxially mounted within the inner hole of the flexible wheel 200. The external teeth 240 of the flexible wheel 200 mesh with the internal teeth 110 of the rigid wheel 100. Therefore, when the wave generator 300 rotates, it can drive the flexible wheel 200 and the rigid wheel 100 to rotate relative to each other. The external teeth 240 are disposed in the cylindrical portion 210 of the flexible wheel 200, which is also connected to a diaphragm 220. The diaphragm 220 is connected to a flange 230. The external tooth portion 240 includes a protruding tooth 241. Since the two ends of the protruding tooth 241 along the axial direction are prone to interference with the internal tooth portion 110, the protruding tooth 241 is provided to include a first modified section 242, an intermediate section 243 and a second modified section 244 connected in sequence. The tooth height of the first modified section 242 and the tooth height of the second modified section 244 gradually decrease in the direction away from the intermediate section 243, which can effectively reduce the occurrence of interference between the protruding tooth 241 and the internal tooth portion 110. Meanwhile, the width ratio of the first modified section 242 to the width of the tooth 241 is reasonably designed to be between 0.2 and 0.35, the width ratio of the middle section 243 to the width of the tooth 241 is between 0.35 and 0.45, and the width ratio of the second modified section 244 to the width of the tooth 241 is between 0.25 and 0.4. This design can ensure the meshing stability of the tooth 241 and the internal tooth 110, while also reducing the interference between the tooth 241 and the internal tooth 110, thereby reducing the friction and wear of the tooth surface and extending the life of the flexible gear 200.

[0056] 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.

[0057] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A harmonic reducer characterized by, The application relates to a wave generator, comprising: a rigid gear provided with an inner tooth part; a flexible gear comprising a barrel part, a diaphragm part and a flange part, the barrel part being provided with an outer tooth part matched with the inner tooth part, the outer tooth part being coaxially arranged in the inner tooth part, the diaphragm part being connected to one end of the barrel part away from the outer tooth part and extending outwardly of the barrel part, and the flange part being connected to an outer circumferential edge of the diaphragm part; a wave generator coaxially arranged in a bore of the flexible gear, the wave generator being configured to mesh the outer tooth part with the inner tooth part when rotating; wherein the outer tooth part comprises a plurality of teeth arranged in a circumferential direction of the barrel part, from the outer tooth part to the flange part, the teeth comprise a first modified section, an intermediate section and a second modified section connected in sequence, a tooth height of the first modified section and a tooth height of the second modified section gradually decrease in a direction away from the intermediate section, in a direction parallel to an axis of rotation of the wave generator, a tooth width of the teeth is Lf1, a width of the first modified section is Lf2, a width of the intermediate section is Lf3, and a width of the second modified section is Lf4, and the following conditions are met: 0.2*Lf1<=Lf2<=0.35*Lf1; 0.35*Lf1<=Lf3<=0.45*Lf1; 0.25*Lf1<=Lf4<=0.4*Lf1.

2. The harmonic reducer of claim 1, wherein: a tooth top of the first modified section is configured as a first inclined surface inclined in a direction away from the intermediate section and towards the axis of rotation, and a tooth top of the second modified section is configured as a second inclined surface inclined in a direction away from the intermediate section and towards the axis of rotation, and an inclination angle of the second inclined surface is greater than an inclination angle of the first inclined surface.

3. The harmonic reducer of claim 1, wherein: the tooth top of the first modified section is configured as the first inclined surface inclined in the direction away from the intermediate section and towards the axis of rotation, and the inclination angle of the first inclined surface is alpha1, and the following condition is met: 0.3<=alpha1<=1.

4. The harmonic reducer of claim 3, wherein: the tooth top of the second modified section is configured as the second inclined surface inclined in the direction away from the intermediate section and towards the axis of rotation, and the inclination angle of the second inclined surface is beta1, and the following conditions are met: 0.3<=beta1<=1, and beta1>alpha1.

5. The harmonic reducer of claim 1, wherein: a minimum distance between an end wall of the barrel part at one end away from the flange part and the flange part is Lf, and a maximum length of the inner tooth part in the direction of the axis of rotation is Lc, and the following condition is met: 0.5*Lf<=Lc<=0.6*Lf.

6. The harmonic reducer of claim 1, wherein: the minimum distance between the end wall of the barrel part at one end away from the flange part and the flange part is Lf, and the following condition is met: 0.45*Lf<=Lf1<=0.55*Lf.

7. The harmonic reducer of claim 1, wherein: an end of the second modified section towards the flange part is connected to the barrel part through an arc-shaped section.

8. The harmonic reducer of claim 1, wherein: The junction of the diaphragm part and the cylinder part is configured as a corner part, the inner side and the outer side of the corner part are configured as a first circular arc segment and a second circular arc segment respectively, the outer side of the diaphragm part is configured as a first segment, the inner side of the diaphragm part is configured as a first curved segment and a second segment, the two ends of the first curved segment are connected to the inner side of the flange part and the second segment respectively, the first curved segment is composed of at least two circular arc segments, one of the first segment and the second segment is a first straight segment, and the other is a second curved segment, the second curved segment is composed of at least one circular arc segment.

9. The harmonic reducer of claim 1 or 8, wherein: The junction of the diaphragm part and the cylinder part is configured as a corner part, the cylinder part includes a first cylinder segment and a second cylinder segment connected to each other, the outer tooth part is provided on the first cylinder segment, the inner side of the second cylinder segment is configured as a third segment, the outer side of the second cylinder segment is configured as a fourth segment, one of the third segment and the fourth segment is a second straight segment, and the other is a third straight segment and a third curved segment connected to each other, the third curved segment is closer to the corner part than the third straight segment, and the third curved segment is composed of at least two circular arc segments.

10. The harmonic reducer of claim 1, wherein: The effective length of the diaphragm part is Lf5, the radial distances from the points a, b, d, e of the diaphragm part to the end of the flange part connected to the diaphragm part are La, Lb, Ld, Le respectively, wherein: La=0.02*Lf5; Lb=0.1*Lf5; Ld=0.45*Lf5; Le=0.86*Lf5; The wall thicknesses of the diaphragm part at the points a, b, d, e are ta, tb, td, te respectively; The junction of the diaphragm part and the cylinder part is configured as a corner part, the maximum wall thickness of the corner part is to; It is satisfied that td 11. The harmonic reducer of claim 1 or 10, wherein: The minimum distance between the end wall of the cylinder part away from the end of the flange part and the flange part is Lf, the axial distances from the points g, h, i, j, k, m of the cylinder part to the outer side wall of the flange part are Lg, Lh, Li, Lj, Lk, Lm respectively, wherein: Lg=0.04*Lf; Lh=0.10*Lf; Li=0.20*Lf; Lj=0.30*Lf; Lk=0.40*Lf; Lm=0.45*Lf; The wall thicknesses of the cylinder part at the points g, h, i, j, k, m are tg, th, ti, tj, tk, tm respectively; The junction of the diaphragm part and the cylinder part is configured as a corner part, the maximum wall thickness of the corner part is to; It is satisfied that th 12. Industrial robot, characterized in that: The harmonic reducer includes the harmonic reducer of any one of claims 1 to 11.

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