Harmonic reducer and industrial robot

Abstract

The application discloses a harmonic reducer and an industrial robot, and relates to the technical field of reducers, wherein the harmonic reducer comprises a rigid gear, a flexible gear, a wave generator and a supporting bearing, the wave generator is located in the flexible gear, first and second groove bodies are arranged between the inner bearing ring and the outer bearing ring of the supporting bearing, the first groove body is used for mounting a first rolling body, and the second groove body is used for mounting a second rolling body. Since the first mounting portion of the rigid gear is connected to the middle portion of the inner tooth portion, and the first and second thin wall sections of the inner tooth portion are respectively connected to the two ends of the first mounting portion, the first and second thin wall sections can produce a certain degree of elastic deformation. When the outer tooth portion is subjected to excessive force, the interference of the first and second thin wall sections can be reduced under the elastic deformation of the first and second thin wall sections, so that the vibration and noise of the harmonic reducer are reduced, the friction and wear of the flexible gear are reduced, and the service life of the flexible gear is prolonged.

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 hole 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 can drive 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. However, when the flexible wheel is subjected to significant pressure, the two ends of the outer teeth along the axial direction are prone to interference with the inner teeth, leading to increased wear, vibration, and noise, and a reduced service life of the flexible wheel. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a harmonic reducer that can reduce interference between the flex wheel and the rigid wheel, reduce vibration and noise, and improve the service life of the flex wheel.

[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 a first mounting portion and an internal tooth portion connected to the inner side of the first mounting 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 first mounting portion is connected to the inner bearing ring, and along the axial direction of the wave generator, the first mounting portion is connected to the middle of the inner tooth portion, the inner tooth portion including a first thin-walled section and a second thin-walled section, the first thin-walled section being located at one end of the first mounting portion facing the inner bearing ring, the outer side of the first thin-walled section abutting against the inner side of the inner bearing ring, and the second thin-walled section being located at one end of the first mounting portion away from the inner bearing ring.

[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 flex wheel and partially meshing the outer teeth of the flex wheel with the inner teeth of the rigid wheel, the wave generator's rotation drives the flex wheel 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 the first rolling element, and the second groove is for mounting the second rolling element. The first and second grooves are spaced apart along the axial direction of the wave generator. By using two sets of rolling elements, the load-bearing capacity of the harmonic reducer can be effectively improved, enhancing the assembly efficiency between the bearing assembly and the rigid and flex wheels while maintaining the overall structural compactness. Since the first mounting part of the rigid wheel is connected to the middle of the inner teeth, and the first and second thin-walled sections of the inner teeth are respectively connected to the two ends of the first mounting part, the first and second thin-walled sections can undergo a certain degree of elastic deformation. The outer teeth of the flexible gear engage with the first thin-walled section and the second thin-walled section at both ends along the axial direction, respectively. When the external teeth are subjected to excessive force, the elastic deformation of the first and second thin-walled sections can reduce interference with them, thereby reducing the vibration and noise of the harmonic reducer, reducing the friction and wear of the flexible gear, and improving the service life of the flexible gear.

[0007] According to some embodiments of the present invention, the wave generator further includes a flexible bearing connected to the inner hole of the flexure, the width of the internal teeth is Lc, and the distance between the center line of the first mounting part in the axial direction and the plane containing the center of all rolling elements of the flexible bearing is Lbc, satisfying: Lbc≤0.1*Lc.

[0008] According to some embodiments of the present invention, along the axial direction, the width of the first thin-walled segment is Lc1, the width of the second thin-walled segment is Lc2, and the width of the internal tooth is Lc, satisfying: 0.6*Lc≤Lc1+Lc2≤0.9*Lc.

[0009] According to some embodiments of the present invention, the maximum wall thickness of the first thin-walled section is Tc1, the maximum wall thickness of the second thin-walled section is Tc2, and the inner diameter of the flexible wheel is Df, satisfying: 0.015*Df≤Tc1≤0.05*Df, 0.015*Df≤Tc2≤0.05*Df.

[0010] According to some embodiments of the present invention, the connection between the first thin-walled segment and the first mounting portion is constructed as a first curve, the first curve being composed of at least two arc segments, the first curve connecting to the outer side of the first thin-walled segment at point a1, the first curve connecting to the first mounting portion at point e1, and the distance from point a1 to point e1 along the axial direction being Lwa1, satisfying: 0.1*Lc1≤Lwa1≤0.3*Lc1.

[0011] According to some embodiments of the present invention, the first curve has points b1, c1, and d1. The distance from point a1 to point b1 is Lwb1, the distance from point b1 to point c1 is Lwc1, and the distance from point c1 to point d1 is Lwd1, where Lwb1 = Lwc1 = Lwd1 = Lwa1 / 4. The maximum wall thickness of the first thin-walled segment is Tc1. Along the radial direction of the rigid wheel, the distances from points b1, c1, d1, and e1 to point a1 are Lrb1, Lrc1, Lrd1, and Lre1, respectively, where Lrb1 < Lrc1 < Lrd1 < Lre1, satisfying: 0.1*Tc1 ≤ Lre1 ≤ 0.4*Tc1, and Lrb1 + Lrc1 + Lrd1 ≤ Lre1 / 2.

[0012] According to some embodiments of the present invention, the connection between the second thin-walled segment and the first mounting portion is constructed as a second curve, the second curve being composed of at least two arc segments, the second curve connecting to the outer side of the second thin-walled segment at point a2, the second curve connecting to the first mounting portion at point e2, and the distance from point a2 to point e2 along the axial direction being Lwa2, satisfying: 0.1*Lc1≤Lwa2≤0.3*Lc1.

[0013] According to some embodiments of the present invention, the second curve has points b2, c2, and d2. The distance from point a2 to point b2 is Lwb2, the distance from point b2 to point c2 is Lwc2, and the distance from point c2 to point d2 is Lwd2, where Lwb2 = Lwc2 = Lwd2 = Lwa2 / 4. The maximum wall thickness of the second thin-walled segment is Tc2. Along the radial direction of the rigid wheel, the distances from points b2, c2, d2, and e2 to point a2 are Lrb2, Lrc2, Lrd2, and Lre2, respectively, where Lrb2 < Lrc2 < Lrd2 < Lre2, satisfying: 0.1*Tc2 ≤ Lre2 ≤ 0.4*Tc2, and Lrb2 + Lrc2 + Lrd2 ≤ Lre2 / 2.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] According to some embodiments of the present invention, along the axial direction, the width of the first thin-walled segment is Lc1, the width of the second thin-walled segment is Lc2; the width of the internal tooth is Lc, the inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.2°-(Lc2 / Lc)*0.6°≤α1≤0.8°-(Lc2 / Lc)*0.6°; 0.3°-(Lc1 / Lc)*0.6°≤β1≤0.9°-(Lc1 / Lc)*0.6°.

[0019] According to some embodiments of the present invention, 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.

[0020] 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.

[0021] 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 is provided with a groove that is 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 opposite to each other and form the first groove. The second inner raceway and the second outer raceway are opposite to each other and form the second groove.

[0022] 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.

[0023] According to some embodiments of the present invention, the outer side of the first thin-walled segment abuts against the inner side of the second ring body; the second ring body is provided with a protrusion protruding toward an end away from the first ring body, and the inner side of the protrusion abuts against the outer side of the first mounting portion.

[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 flex wheel, causing the outer teeth of the flex wheel to partially mesh with the inner teeth of the rigid wheel. Therefore, when the wave generator rotates, it can drive the flex wheel and the rigid wheel to rotate relative to each other. A first groove and a second groove are provided between the inner and outer bearing rings of the supporting bearing. The first groove is used to install a first rolling element, and the second groove is used to install 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, and the assembly efficiency between the bearing assembly, the rigid wheel, and the flex wheel can be improved while maintaining the overall structural compactness. Since the first mounting part of the rigid wheel is connected to the middle of the inner teeth, and the first and second thin-walled sections of the inner teeth are respectively connected to the two ends of the first mounting part, the first and second thin-walled sections can undergo a certain degree of elastic deformation. The outer teeth of the flexible gear engage with the first thin-walled section and the second thin-walled section at both ends along the axial direction, respectively. When the external teeth are subjected to excessive force, the elastic deformation of the first and second thin-walled sections can reduce interference with them, thereby reducing the vibration and noise of the harmonic reducer, reducing the friction and wear of the flexible gear, and improving the service life of the flexible gear.

[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 2This is a partial cross-sectional schematic diagram of the flexible wheel and rigid wheel according to an embodiment of the present invention; Figure 3 This is a partial structural schematic diagram of a rigid wheel according to an embodiment of the present invention; Figure 4 for Figure 3 Enlarged view of point B in the middle; Figure 5 for Figure 3 Enlarged view of point C in the middle; Figure 6 This is a partial structural diagram of a flexible wheel according to an embodiment of the present invention; Figure 7 for Figure 1 Enlarged view of point A in the middle; Figure 8 This is a partial cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 9 This is a partial cross-sectional view of the external tooth portion according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of the inner bearing ring according to an embodiment of the present invention; Figure 11 This is a cross-sectional view of the outer bearing ring according to an embodiment of the present invention; Figure 12 This is a graph showing the relationship between the ratio of (Lc1+Lc2) / Lc and torsional stiffness and vibration acceleration in one embodiment of the present invention. Figure 13 This is a graph showing the relationship between the ratio of Tc1 and Df and the stress and vibration acceleration of the rigid wheel in one embodiment of the present invention. Figure 14 This 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 15 This is a graph showing the relationship between the Lbc / Lc ratio and the vibration of the entire machine according to an embodiment of the present invention. Figure 16 This is a diagram showing the relationship between the range of values ​​for α1 and the vibration of the entire machine in one embodiment of the present invention. Figure 17 This is a graph showing the relationship between the range of values ​​for α2 and the vibration of the entire machine in one embodiment of the present invention.

[0028] Icon labels: Harmonic reducer 1000; Rigid wheel 100; internal gear 110; first thin-walled section 111; second thin-walled section 112; first mounting part 120; first curve 130; second curve 140; 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; Third rolling element 321; Support bearing 400; outer bearing ring 410; second mounting part 411; protrusion 412; first outer raceway 413; second outer raceway 414; inner bearing ring 420; protrusion 421; groove 422; first inner raceway 423; 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 2As 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 an internal toothed portion 110, and an external toothed portion 210 engages with the internal toothed portion 110, forming a meshing gap between the external toothed portion 210 and the internal toothed portion 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 1As 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] 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.

[0038] To solve the above problems, refer to Figure 3 As shown, in an embodiment of the present invention, the rigid wheel 100 further includes a first mounting portion 120, and an internal gear portion 110 is connected to the inner side of the first mounting portion 120. The first mounting portion 120 is connected to the inner bearing ring 420, and the connection can be made by fasteners, such as screws, bolts, or pins. Along the axial direction of the wave generator 300, the first mounting portion 120 is connected to the middle part of the internal gear portion 110, and the connection can be integrally formed, welded, etc. It should be noted that the middle part of the internal gear portion 110 refers to the portion along the axial direction of the wave generator 300, i.e. Figure 3 In the left-right direction, the end of the first mounting portion 120 does not coincide with the end of the internal gear portion 110, nor does it protrude outward from the end of the internal gear portion 110; that is, the position between the two axial ends of the internal gear portion 110 belongs to the middle of the internal gear portion 110. It should also be noted that the first mounting portion 120 is connected to the middle of the internal gear portion 110 in several ways: it can be connected to the middle portion but not to the left or right ends; it can be connected to the middle portion, the left end, and the right end simultaneously; or it can be connected to the middle portion and also to one of the left or right ends. The appropriate connection method should be selected based on the specific circumstances.

[0039] Continue to refer to Figure 3 As shown, the internal gear portion 110 includes a first thin-walled section 111 and a second thin-walled section 112. The first thin-walled section 111 is located at the end of the first mounting portion 120 facing the inner bearing ring 420, and the outer side of the first thin-walled section 111 abuts against the inner side of the inner bearing ring 420. The second thin-walled section 112 is located at the end of the first mounting portion 120 away from the inner bearing ring 420. That is, the first thin-walled section 111 is connected to the left end of the first mounting portion 120, and the second thin-walled section 112 is connected to the right end of the first mounting portion 120.

[0040] With the above scheme, since the first mounting part 120 of the rigid wheel 100 is connected to the middle of the internal gear part 110, and the first thin-walled section 111 and the second thin-walled section 112 of the internal gear part 110 are respectively connected to the two ends of the first mounting part 120 along the axial direction, the first thin-walled section 111 and the second thin-walled section 112 can generate a certain degree of elastic deformation. The two ends of the external gear part 210 of the flexible wheel 200 along the axial direction are respectively engaged with the first thin-walled section 111 and the second thin-walled section 112. When the external gear part 210 is subjected to excessive force, the interference with the first thin-walled section 111 and the second thin-walled section 112 can be reduced under the elastic deformation of the first thin-walled section 111 and the second thin-walled section 112, thereby reducing the vibration and noise of the harmonic reducer 1000, reducing the friction and wear of the flexible wheel 200, and improving the service life of the flexible wheel 200. At the same time, because the interference between the external tooth section 210 and the internal tooth section 110 is reduced, the installation accuracy requirement for the rigid wheel 100 is reduced, thereby improving the production qualification rate of the harmonic reducer 1000.

[0041] Reference Figure 2 As shown, in this embodiment of the invention, the width of the internal tooth portion 110 is Lc, and the axial centerline of the first mounting portion 120 is L, which extends radially along the wave generator 300. The plane containing the centers of all the third rolling elements 321 of the flexible bearing 320 is S, which also extends radially along the wave generator 300 and is parallel to the centerline L. The distance between the centerline L and the plane S is Lbc, satisfying: Lbc ≤ 0.1 * Lc. This formula is equivalent to Lbc / Lc ≤ 0.1. For example, the value of Lbc / Lc can be 0.1, 0.05, 0.01, 0, -0.05, -0.15, etc.

[0042] Reference Figure 15 As shown, Figure 15 The horizontal axis represents the range of values ​​for Lbc / Lc, and the vertical axis represents the magnitude of the overall vibration of the harmonic reducer 1000. From Figure 15 As can be seen, with the gradual increase of Lbc / Lc, the overall vibration first decreases and then increases, with the minimum vibration occurring at Lbc=0. This means that the closer the centerline L of the first mounting section 120 is to the plane S, the better, and the centerline L can coincide with the plane S. The width Lc of the internal gear section 110 is usually fixed. When Lbc is greater than 0.1*Lc, the length of the first thin-walled section 111 becomes too long, easily leading to deformation and bending; the length of the second thin-walled section 112 becomes too short, making it difficult to achieve elastic deformation. Alternatively, the length of the first thin-walled section 111 may be too short, making it difficult to achieve elastic deformation; the length of the second thin-walled section 112 may be too long, easily leading to deformation and bending. Therefore, a reasonable design where the distance between the centerline L and the plane S is less than 0.1*Lc is beneficial for the wave generator 300 to support the rigid wheel 100, thereby improving the load-bearing capacity of the harmonic reducer 1000 and reducing overall vibration and noise.

[0043] Reference Figure 3 As shown, in this embodiment of the invention, along the axial direction of the wave generator 300, the width of the first thin-walled section 111 is Lc1, and the width of the second thin-walled section 112 is Lc2. It should be noted that the width Lc1 of the first thin-walled section 111 refers to the maximum distance between the left end face of the first mounting portion 120 and the left end face of the first thin-walled section 111. The width Lc2 of the second thin-walled section 112 refers to the maximum distance between the right end face of the first mounting portion 120 and the right end face of the second thin-walled section 112. The width Lc of the internal tooth portion 110 refers to the maximum distance between the left and right end faces of the internal tooth portion 110. The width Lc of the internal tooth portion 110, the width Lc1 of the first thin-walled section 111, and the width Lc2 of the second thin-walled section 112 satisfy: 0.6*Lc≤Lc1+Lc2≤0.9*Lc. This formula is equivalent to 0.6≤(Lc1+Lc2) / Lc≤0.9. For example, the value of (Lc1+Lc2) / Lc can be 0.6, 0.65, 0.7, 0.8, 0.85, 0.9, etc.

[0044] Reference Figure 12 As shown, Figure 12 The horizontal axis represents the value of (Lc1+Lc2) / Lc, the vertical axis on the left represents torsional stiffness, and the vertical axis on the right represents vibration acceleration. Torsional stiffness refers to the slope of the line segment taken on the mechanical hysteresis loop, expressed as the torque change corresponding to a unit torsional angle. Torsional stiffness describes the ratio between the relative torsional angle caused by elastic deformation and the load. The greater the torsional stiffness, the smaller the torsional angle generated by the output shaft when subjected to external forces, and the higher the positioning accuracy. 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 the wear and energy loss of the harmonic reducer 1000, and improve the overall performance and life of the reducer.

[0045] from Figure 12As can be seen, when the value of (Lc1+Lc2) / Lc is less than 0.6, although the torsional stiffness is high, the vibration acceleration of the harmonic reducer 1000 is relatively large, resulting in poor operational stability. When the value of (Lc1+Lc2) / Lc is greater than 0.9, although the vibration acceleration is smaller, the torsional stiffness is also smaller. Therefore, reasonably designing the value of (Lc1+Lc2) / Lc within the range of 0.6 to 0.9 can reduce the vibration acceleration of the harmonic reducer 1000, thereby improving the operational stability of the harmonic reducer 1000, while also ensuring that the torsional stiffness is at an appropriate level, thereby improving the torsional resistance and positioning accuracy of the harmonic reducer 1000.

[0046] Reference Figure 1 and Figure 3 As shown, in the embodiment of the present invention, the maximum wall thickness of the first thin-walled section 111 is Tc1, and the maximum wall thickness of the second thin-walled section 112 is Tc2. The maximum wall thickness Tc1 of the first thin-walled section 111 and the maximum wall thickness Tc2 of the second thin-walled section 112 refer to the maximum thickness of the first thin-walled section 111 and the second thin-walled section 112 in the radial direction of the wave generator 300. The inner diameter of the flexible wheel 200 is Df, satisfying: 0.015*Df≤Tc1≤0.05*Df, 0.015*Df≤Tc2≤0.05*Df. Wherein, the above formula is equivalent to 0.015≤Tc1 / Df≤0.05, 0.015≤Tc2 / Df≤0.05. The values ​​of Tc1 / Df can be 0.015, 0.02, 0.03, 0.04, and 0.05; the values ​​of Tc2 / Df can be 0.015, 0.02, 0.03, 0.04, and 0.05.

[0047] Reference Figure 13 As shown, Figure 13 The horizontal axis represents the value of Tc1 / Df, the vertical axis on the left represents the stress on the rigid wheel 100, and the vertical axis on the right represents the vibration acceleration of the harmonic reducer 1000. Since the values ​​of Tc1 / Df and Tc2 / Df are equal in this embodiment, therefore... Figure 13 It can also be used to represent the relationship between the value of Tc2 / Df and the vibration acceleration and the stress of the rigid wheel 100. From Figure 13As can be seen, when the values ​​of Tc1 / Df and Tc2 / Df are less than 0.015, although the vibration acceleration of the harmonic reducer 1000 is low, the stress on the rigid wheel 100 is high, and the load-bearing capacity of the rigid wheel 100 is reduced. When the values ​​of Tc1 / Df and Tc2 / Df are greater than 0.05, the stress on the rigid wheel 100 is low, but the vibration acceleration of the harmonic reducer 1000 is high, resulting in unstable operation. Therefore, by reasonably designing the values ​​of Tc1 / Df and Tc2 / Df to be within the range of 0.015 to 0.05, the vibration acceleration can be reduced to improve the smoothness of the operation of the harmonic reducer 1000, and the stress on the rigid wheel 100 can be reduced to improve its load-bearing capacity.

[0048] Reference Figure 4 As shown in the present invention and embodiments, the first curve 130 is connected to the outer side of the first thin-walled segment 111 at point a1, and the first curve 130 is connected to the first mounting portion 120 at point e1. Along the axial direction of the wave generator 300, the distance from point a1 to point e1 is Lwa1, satisfying: 0.1*Lc1≤Lwa1≤0.3*Lc1. This formula is equivalent to 0.1≤Lwa1 / Lc1≤0.3, for example, the value of Lwa1 / Lc1 can be 0.1, 0.15, 0.2, 0.25, 0.3, etc. The above formula reflects the proportion range of the first curve 130 along the axial direction of the first thin-walled segment 111. When the value of Lwa1 / Lc1 is less than 0.1, that is, the length of the first curve 130 along the axial direction is short, it is difficult to reduce the stress at the connection between the first mounting portion 120 and the first thin-walled segment 111. When the value of Lwa1 / Lc1 is greater than 0.3, the length of the first curve 130 along the axial direction is too long, which is not conducive to the abutment fit between the inner bearing ring 420 and the outer wall of the first thin-walled section 111, affecting the fit accuracy. Therefore, by reasonably designing the value of Lwa1 / Lc1 to be within the range of 0.1 to 0.3, it is possible to ensure the fit accuracy between the inner bearing ring 420 and the first thin-walled section 111 while reducing the stress at the connection between the first thin-walled section 111 and the first mounting part 120, thereby reducing stress concentration and improving the load-bearing capacity of the rigid wheel 100.

[0049] Reference Figure 4As shown in the embodiment of the present invention, the first curve 130 has points b1, c1, and d1. The distance from point a1 to point b1 is Lwb1, the distance from point b1 to point c1 is Lwc1, and the distance from point c1 to point d1 is Lwd1. Lwb1 = Lwc1 = Lwd1 = Lwa1 / 4, meaning the first curve 130 is divided into four equal parts axially. Along the radial direction of the rigid wheel 100, the distances from points b1, c1, d1, and e1 to point a1 are Lrb1, Lrc1, Lrd1, and Lre1, respectively, where Lrb1 < Lrc1 < Lrd1 < Lre1, satisfying: 0.1*Tc ≤ Lre1 ≤ 0.4*Tc, and Lrb1 + Lrc1 + Lrd1 ≤ Lre1 / 2. Wherein, 0.1*Tc≤Lre1≤0.4*Tc is equivalent to 0.1≤Lre1 / Tc≤0.4, for example, the value of Lre1 / Tc can be 0.1, 0.2, 0.3, 0.4, etc. It is understandable that when Lre1 / Tc is less than 0.1, and Lrb1+Lrc1+Lrd1>Lre1 / 2, that is, the height of the first curve 130 in the radial direction of the rigid wheel 100 is relatively low, it is difficult to provide a smooth transition at the connection between the first thin-walled section 111 and the first mounting part 120, and the effect of reducing stress concentration is not obvious. When Lre1 / Tc is greater than 0.4, that is, the height of the first curve 130 in the radial direction of the rigid wheel 100 is relatively high, which is not conducive to the abutment fit between the inner bearing ring 420 and the first thin-walled section 111. Therefore, by reasonably designing the value of Lre1 / Tc to be in the range of 0.1 to 0.4, and Lrb1+Lrc1+Lrd1≤Lre1 / 2, the stress concentration at the connection between the first thin-walled section 111 and the first mounting part 120 can be effectively reduced. At the same time, it is beneficial to the abutment fit between the inner bearing ring 420 and the first thin-walled section 111, thereby improving the installation efficiency.

[0050] Table 1: Comparison of maximum stress at the connection between the first thin-walled section 111 and the first mounting part 120 for three different schemes

[0051] In Table 1 above, Scheme 1 is a scheme in which the first mounting part 120 and the first thin-walled segment 111 are directly connected without the first curve 130; Scheme 2 is a scheme in which the first mounting part 120 and the first thin-walled segment 111 are connected by a straight segment; Scheme 3 is the scheme of this embodiment, which is a scheme in which the first curve 130 is used to connect the first mounting part 120 and the first thin-walled segment 111. As can be seen from the table, the maximum stress when the first mounting part 120 and the first thin-walled segment 111 are directly connected is 222 MPa; while when the first mounting part 120 and the second thin-walled segment 112 are connected by a straight segment, the maximum stress is 198 MPa. Scheme 2 reduces the maximum stress by 10.8% compared to Scheme 1. In the scheme of this embodiment, the maximum stress is 172 MPa, which is 22.5% lower than the maximum stress of Scheme 1. Therefore, the scheme of this embodiment can effectively reduce the maximum stress at the connection between the first thin-walled segment 111 and the first mounting part 120, effectively avoiding stress concentration, thereby improving the load-bearing capacity of the rigid wheel 100.

[0052] Reference Figure 4 As shown, in the present invention and its embodiments, the second curve 140 connects to the outer side of the second thin-walled segment 112 at point a2, and the second curve 140 connects to the first mounting portion 120 at point e2. Along the axial direction of the wave generator 300, the distance from point a2 to point e2 is Lwa2, satisfying: 0.1*Lc2≤Lwa2≤0.3*Lc2. This formula is equivalent to 0.1≤Lwa2 / Lc2≤0.3, for example, the value of Lwa2 / Lc2 can be 0.1, 0.15, 0.2, 0.25, 0.3, etc. The above formula reflects the proportion range of the second curve 140 along the axial direction of the second thin-walled segment 112. When the value of Lwa2 / Lc2 is less than 0.1, that is, the length of the second curve 140 along the axial direction is short, it is difficult to reduce the stress at the connection between the first mounting portion 120 and the second thin-walled segment 112. When the value of Lwa2 / Lc2 is greater than 0.3, the length of the second curve 140 along the axial direction is too long, which is not conducive to the deformation of the second thin-walled section 112. Therefore, by reasonably designing the value of Lwa2 / Lc2 to be within the range of 0.1 to 0.3, the stress at the connection between the second thin-walled section 112 and the first mounting part 120 can be reduced, thereby reducing stress concentration and improving the load-bearing capacity of the rigid wheel 100.

[0053] Reference Figure 5As shown in the embodiment of the present invention, the second curve 140 has points b2, c2, and d2. The distance from point a2 to point b2 is Lwb2, the distance from point b2 to point c2 is Lwc2, and the distance from point c2 to point d2 is Lwd2. Lwb2 = Lwc2 = Lwd2 = Lwa2 / 4, meaning the second curve 140 is divided into four equal parts axially. Along the radial direction of the rigid wheel 100, the distances from points b2, c2, d2, and e2 to point a2 are Lrb2, Lrc2, Lrd2, and Lre2, respectively, where Lrb2 < Lrc2 < Lrd2 < Lre2, satisfying: 0.1*Tc ≤ Lre2 ≤ 0.4*Tc, and Lrb2 + Lrc2 + Lrd2 ≤ Lre2 / 2. Wherein, 0.2*Tc≤Lre2≤0.4*Tc is equivalent to 0.1≤Lre2 / Tc≤0.4, for example, the value of Lre2 / Tc can be 0.1, 0.2, 0.3, 0.4, etc. It is understandable that when Lre2 / Tc is less than 0.1, and Lrb2+Lrc2+Lrd2>Lre2 / 2, that is, the height of the second curve 140 in the radial direction of the rigid wheel 100 is relatively low, close to a right angle, making it difficult to provide a smooth transition at the connection between the second thin-walled section 112 and the first mounting part 120, and the effect of reducing stress concentration is not significant. When Lre2 / Tc is greater than 0.4, that is, the height of the second curve 140 in the radial direction of the rigid wheel 100 is relatively high, which is not conducive to the deformation of the second thin-walled section 112. Therefore, by reasonably designing the value of Lre2 / Tc to be within the range of 0.1 to 0.4, and ensuring that Lrb2+Lrc2+Lrd2≤Lre2 / 2, the stress concentration at the connection between the second thin-walled section 112 and the first mounting part 120 can be effectively reduced, thereby improving the service life of the rigid wheel 100.

[0054] Table 2: Comparison of maximum stress at the connection between the second thin-walled section 112 and the first mounting part 120 for three different schemes

[0055] In Table 2 above, Scheme 1 is a scheme in which the first mounting part 120 and the second thin-walled section 112 are directly connected without the second curve 140; Scheme 2 is a scheme in which the first mounting part 120 and the second thin-walled section 112 are connected by a straight section; Scheme 3 is the scheme of this embodiment, which is the scheme in which the second curve 140 is used to connect the first mounting part 120 and the second thin-walled section 112. As can be seen from the table, the maximum stress when the first mounting part 120 and the second thin-walled section 112 are directly connected is 198 MPa; while when the first mounting part 120 and the second thin-walled section 112 are connected by a straight section, the maximum stress is 179 MPa. Scheme 2 reduces the maximum stress by 9.1% compared to Scheme 1. In the scheme of this embodiment, the maximum stress is 166 MPa, which is 15.7% lower than the maximum stress of Scheme 1. Therefore, the scheme of this embodiment can effectively reduce the maximum stress at the connection between the second thin-walled section 112 and the first mounting part 120, effectively avoiding stress concentration, thereby improving the load-bearing capacity of the rigid wheel 100.

[0056] Reference Figure 7 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.

[0057] Reference Figure 8 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 7From 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.

[0058] Continue to refer to Figure 8 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.

[0059] Reference Figure 2 and Figure 9As 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.

[0060] 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.

[0061] 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.

[0062] Reference Figure 9As 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.

[0063] Continue to refer to Figure 9 As shown, the inclination angle of the first inclined plane 2111 is α1, satisfying: 0.2° - (Lc2 / Lc)*0.6° ≤ α1 ≤ 0.8° - (Lc2 / Lc)*0.6°. Where (Lc2 / Lc)*0.6° is less than or equal to 0.2°, and (Lc2 / Lc)*0.6° is less than or equal to 0.8°. Once the ratio of Lc2 / Lc is determined, the range of values ​​for α1 can also be determined. For example, if Lc2 / Lc = 1 / 6, the range of values ​​for α1 is 0.1° ≤ α1 ≤ 0.7°. (Refer to...) Figure 16 As shown, Figure 16 The horizontal axis represents the range of values ​​for α1, and the vertical axis represents the overall vibration magnitude of the harmonic reducer 1000. As the value of α1 gradually increases, the overall vibration first increases and then decreases. When α1 is less than 0.2° - (Lc2 / Lc) * 0.6°, 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 section 110 and the external tooth section 210, and the overall vibration increases. When α1 is greater than 0.8° - (Lc2 / Lc) * 0.6°, it is easy to reduce the effective area when the first tooth section 211 and the internal tooth section 110 mesh, thus leading to poor meshing stability, which also leads to an increase in overall vibration. Therefore, a reasonable design of the value of α1 can effectively reduce the interference between the internal tooth section 110 and the external tooth section 210, reduce the overall vibration, improve the service life of the flexible gear 200, and at the same time ensure that the external tooth section 210 has appropriate strength and high reliability.

[0064] Continue to refer to Figure 9As shown, the inclination angle of the second inclined plane 2112 is β1, satisfying: 0.3° - (Lc1 / Lc)*0.6° ≤ β1 ≤ 0.9° - (Lc1 / Lc)*0.6°. Where 0.3° - (Lc1 / Lc)*0.6° is less than or equal to 0.3°, and (Lc1 / Lc)*0.6° is less than or equal to 0.9°. Once the ratio of Lc1 / Lc is determined, the range of values ​​for β1 can also be determined. For example, if Lc1 / Lc = 1 / 6, the range of values ​​for β1 is 0.2° ≤ β1 ≤ 0.8°. (Refer to...) Figure 17 As shown, Figure 17 The horizontal axis represents the range of values ​​for β1, and the vertical axis represents the overall vibration magnitude of the harmonic reducer 1000. As the value of β1 gradually increases, the overall vibration first increases and then decreases. When β1 is less than 0.3° - (Lc1 / Lc) * 0.6°, it is difficult to reduce the interference between the internal gear 110 and the external gear 210, resulting in increased overall vibration. When β1 is greater than 0.9° - (Lc1 / Lc) * 0.6°, it easily leads to a reduction in the effective area when the second tooth segment 212 meshes with the internal gear 110, thus causing poor meshing stability and also increasing overall vibration. Therefore, a reasonable design of the value of β1 to reduce overall vibration can effectively reduce the interference between the internal gear 110 and the external gear 210, improve the service life of the flexspline 200, and ensure that the external gear 210 has appropriate strength and high reliability.

[0065] It should be noted that, since the internal tooth portion 110 includes a first thin-walled segment 111 and a second thin-walled segment 112, the first thin-walled segment 111 and the second thin-walled segment 112 can undergo a certain degree of elastic deformation, thereby reducing the interference between the internal tooth portion 110 and the external tooth portion 210. Therefore, the modification angles for the first tooth segment 211 and the second tooth segment 212 can be appropriately reduced or left unmodified to ensure the overall strength of the external tooth portion 210.

[0066] Continue to refer to Figure 9As 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. The inclination angle of the third inclined surface 2121 can be the same as or different from that of the first inclined surface 2111. The inclination angle of the third inclined surface 2121 is α2, which satisfies: 0.2°-(Lc2 / Lc)*0.6°≤α2≤0.8°-(Lc2 / Lc)*0.6°. When α2 is less than 0.2°-(Lc2 / Lc)*0.6°, 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 0.8°-(Lc2 / Lc)*0.6°, it is easy to reduce the strength of the external tooth 210, and tearing is likely to occur between adjacent teeth.

[0067] A fourth inclined surface 2122 is provided between two adjacent second tooth segments 212. The fourth inclined surface 2122 is inclined away from the third tooth segment 213 and towards the axis of rotation. The inclination angle of the fourth inclined surface 2122 can be the same as or different from the inclination angle of the second inclined surface 2112. The inclination angle of the fourth inclined surface 2122 is β2, which satisfies: 0.3°-(Lc1 / Lc)*0.6°≤β2≤0.9°-(Lc1 / Lc)*0.6°. When β2 is less than 0.3°-(Lc1 / Lc)*0.6°, it is difficult to reduce the interference between the internal tooth portion 110 and the external tooth portion 210. When β2 is greater than 0.4°, it is easy to reduce the strength of the external tooth portion 210, and tearing is likely to occur between adjacent protrusions. 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 210, thereby reducing the friction and wear of the tooth surface and extending the life of the flexible gear 200.

[0068] Table 3: Comparison of tooth surface contact area under different schemes

[0069] For example, referring to Table 3 above, Scheme 1 is the scheme in the related technology, 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 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 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 19.2%, i.e., the tooth width of the flexible gear 200 increases. Furthermore, adding a modification scheme on this basis increases the improvement by 38.5% 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.

[0070] 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 6 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.

[0071] Reference Figure 14 As shown, Figure 14 The horizontal axis of the curve represents the value of Tf / Df, and the vertical axis represents the root stress of the flexspline 200. From... Figure 14As can be seen, as the value of Tf / Df gradually increases, the tooth root stress on the flexure 200 first decreases and then increases, with a minimum value for the tooth root stress. Therefore, for flexures 200 of the same specification but with different reduction ratios, using the natural logarithm function LnN to eliminate the influence of the reduction ratio R, it is only necessary to ensure that the value of Tf / Df is limited to the range of 0.0043ln(R)-0.0061 and 0.005ln(R)-0.0036. This can effectively reduce the stress on the flexure 200, simplify the design of the flexure 200, improve production efficiency, and is suitable for improving the stress distribution of harmonic reducers 1000 with different reduction ratios R, reducing the stress on the flexure 200 during deformation. Furthermore, compared to flexures in related technologies, the tooth root wall thickness Tf of the flexure 200 in this embodiment is increased, which can effectively improve the load-bearing capacity and torsional stiffness of the harmonic reducer 1000.

[0072] 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.

[0073] Reference Figure 7 , Figure 10 and Figure 11As 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.

[0074] Reference Figure 7 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.

[0075] Continue to refer to Figure 7 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.

[0076] Continue to refer to Figure 7As shown, in an embodiment of the present invention, the outer side of the first thin-walled segment 111 abuts against the inner side of the second ring 426. Along the axial direction of the wave generator 300, the end of the second ring 426 away from the first ring 425 abuts against the end of the first mounting portion 120 facing the first thin-walled segment 111, which can play a positioning role for the second ring 426, facilitating the assembly of the second ring 426 and improving assembly efficiency.

[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. Since the first mounting portion 120 of the rigid wheel 100 is connected to the middle of the internal gear portion 110, and the first thin-walled section 111 and the second thin-walled section 112 of the internal gear portion 110 are respectively connected to the two ends of the first mounting portion 120, the first thin-walled section 111 and the second thin-walled section 112 can generate a certain degree of elastic deformation. The two ends of the external gear portion 210 of the flexible wheel 200 along the axial direction are respectively engaged with the first thin-walled section 111 and the second thin-walled section 112. When the external gear portion 210 is subjected to excessive force, the interference with the first thin-walled section 111 and the second thin-walled section 112 can be reduced under the elastic deformation of the first thin-walled section 111 and the second thin-walled section 112, thereby reducing the vibration and noise of the harmonic reducer 1000, reducing the friction and wear of the flexible wheel 200, and improving the service life of the flexible wheel 200.

[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: The rigid wheel includes a first mounting portion and an internal tooth portion connected to the inner side of the first mounting portion; 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. The first mounting portion is connected to the inner bearing ring along the axial direction of the wave generator. The first mounting portion is connected to the middle of the inner tooth portion. The inner tooth portion includes a first thin-walled section and a second thin-walled section. The first thin-walled section is located at the end of the first mounting portion facing the inner bearing ring, and the outer side of the first thin-walled section abuts against the inner side of the inner bearing ring. The second thin-walled section is located at the end of the first mounting portion away from the inner bearing ring.

2. The harmonic reducer according to claim 1, characterized in that: The wave generator also includes a flexible bearing connected to the inner hole of the flexure, the width of the internal teeth is Lc, and the distance between the center line of the first mounting part in the axial direction and the plane containing the center of all rolling elements of the flexible bearing is Lbc, satisfying: Lbc≤0.1*Lc.

3. The harmonic reducer according to claim 1, characterized in that: Along the axial direction, the width of the first thin-walled section is Lc1, the width of the second thin-walled section is Lc2, and the width of the internal tooth is Lc, satisfying: 0.6*Lc≤Lc1+Lc2≤0.9*Lc.

4. The harmonic reducer according to claim 1 or 2, characterized in that: The maximum wall thickness of the first thin-walled section is Tc1, the maximum wall thickness of the second thin-walled section is Tc2, and the inner diameter of the flexible wheel is Df, satisfying: 0.015*Df≤Tc1≤0.05*Df, 0.015*Df≤Tc2≤0.05*Df.

5. The harmonic reducer according to claim 1 or 2, characterized in that: The connection between the first thin-walled segment and the first mounting part is constructed as a first curve, which is composed of at least two arc segments. The first curve is connected to the outer side of the first thin-walled segment at point a1, and the first curve is connected to the first mounting part at point e1. Along the axial direction, the distance from point a1 to point e1 is Lwa1, which satisfies: 0.1*Lc1≤Lwa1≤0.3*Lc1.

6. The harmonic reducer according to claim 5, characterized in that: The first curve has points b1, c1 and d1. The distance from point a1 to point b1 is Lwb1, the distance from point b1 to point c1 is Lwc1, the distance from point c1 to point d1 is Lwd1, and Lwb1 = Lwc1 = Lwd1 = Lwa1 / 4. The maximum wall thickness of the first thin-walled section is Tc1. Along the radial direction of the rigid wheel, the distances between points b1, c1, d1, e1 and a1 are Lrb1, Lrc1, Lrd1 and Lre1, respectively, where Lrb1 < Lrc1 < Lrd1 < Lre1, satisfying: 0.1*Tc1 ≤ Lre1 ≤ 0.4*Tc1, Lrb1 + Lrc1 + Lrd1 ≤ Lre1 / 2.

7. The harmonic reducer according to claim 1 or 2, characterized in that: The connection between the second thin-walled segment and the first mounting part is constructed as a second curve, which consists of at least two arc segments. The second curve connects to the outer side of the second thin-walled segment at point a2, and the second curve connects to the first mounting part at point e2. Along the axial direction, the distance from point a2 to point e2 is Lwa2, which satisfies: 0.1*Lc1≤Lwa2≤0.3*Lc1.

8. The harmonic reducer according to claim 7, characterized in that: The second curve has points b2, c2 and d2. The distance from point a2 to point b2 is Lwb2, the distance from point b2 to point c2 is Lwc2, and the distance from point c2 to point d2 is Lwd2. Lwb2 = Lwc2 = Lwd2 = Lwa2 / 4. The maximum wall thickness of the second thin-walled section is Tc2. Along the radial direction of the rigid wheel, the distances between points b2, c2, d2, e2 and a2 are Lrb2, Lrc2, Lrd2 and Lre2, respectively, where Lrb2 < Lrc2 < Lrd2 < Lre2, satisfying: 0.1*Tc2 ≤ Lre2 ≤ 0.4*Tc2, and Lrb2 + Lrc2 + Lrd2 ≤ Lre2 / 2.

9. 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.

10. The harmonic reducer according to claim 9, 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.

11. The harmonic reducer according to claim 10, 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.

12. The harmonic reducer according to claim 11, 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.

13. The harmonic reducer according to claim 10, characterized in that: Along the axial direction, the width of the first thin-walled segment is Lc1, and the width of the second thin-walled segment is Lc2; the width of the internal tooth is Lc, the inclination angle of the first tooth segment is α1, and the inclination angle of the second tooth segment is β1, satisfying: 0.2°-(Lc2 / Lc)*0.6°≤α1≤0.8°-(Lc2 / Lc)*0.6°; 0.3°-(Lc1 / Lc)*0.6°≤β1≤0.9°-(Lc1 / Lc)*0.6°.

14. The harmonic reducer according to claim 1 or 2, characterized in that: 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.

15. The harmonic reducer according to claim 1 or 2, 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.

16. 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 respectively the first inner raceway and the second inner raceway. 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.

17. The harmonic reducer according to claim 16, 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.

18. The harmonic reducer according to claim 17, characterized in that: The outer side of the first thin-walled section abuts against the inner side of the second ring body; the second ring body has a protrusion extending toward the end away from the first ring body, and the inner side of the protrusion abuts against the outer side of the first mounting part.

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

Images