Harmonic reduction mechanism, harmonic reducer and robot

Abstract

The present invention provides a harmonic reduction mechanism, a harmonic speed reducer, and a robot, wherein the harmonic reduction mechanism includes a flexspline, a rigid pulley, and a wave generator, wherein the flexspline is sleeved on the wave generator, and the rigid pulley is sleeved on the flexspline and meshes with the flexspline; the reduction ratio of the harmonic reduction mechanism is i, the maximum deformation of the wave generator is ω0, and the modulus of the flexspline is m; wherein a*i+b≤ω0 / m≤a*i+c, a∈[0.002,0.004], b∈[0.6,0.7], c∈[0.8,1], and ω0 and m are both in millimeters; when ω0<m, the flexspline and the rigid pulley mesh without backlash; and when ω0>m, the flexspline and the rigid pulley mesh without interference. According to the technical solution of the present invention, it can be ensured that under different reduction ratios, the flexspline has both good meshing quality and is not easily damaged.

Description

Technical Field

[0001] The present invention belongs to the technical field of harmonic deceleration, and in particular relates to a harmonic deceleration mechanism, a harmonic reducer and a robot. Background Art

[0002] Harmonic gearing is a type of transmission based on the wave deformation principle of flexible elements. A harmonic reducer primarily consists of a flexspline, a rigid pulley, and a wave generator. Compared to conventional gearing, it offers advantages such as a high transmission ratio, compact size, light weight, high precision, and low noise. The wave generator is typically elliptical in shape, and the flexspline is fitted over it. Under the action of the wave generator, the flexspline undergoes elastic deformation, and the teeth of the flexspline at the long shaft end mesh with the teeth of the rigid pulley. Because the number of teeth on the flexspline is smaller than that of the rigid pulley, relative rotation occurs between the two pulleys, thereby transmitting motion and power.

[0003] The deformation process of a flexspline is a fundamentally symmetrical and harmonic process. Different flexspline deformation shapes have different operating capabilities. The criteria for evaluating various solutions are load-bearing capacity, efficiency, and lifespan. Researchers have proposed deformation shapes based on the law of ω = ω0 cos2φ, elliptical deformation shapes, deformation shapes composed of involute segments, deformation shapes composed of circular arcs, and deformation shapes under the action of a concentrated force system. Any of these deformation shapes can be generated using a cam wave generator, which is designed based on the desired flexspline deformation shape.

[0004] The cam wave generator is composed of a flexible bearing that can work in a deformed state. The deformation of the cam is crucial to the working performance of the entire harmonic reducer. Therefore, the design of the cam profile is the main content of the cam wave generator design.

[0005] In a harmonic gear drive, the flexspline has external teeth and the spline has internal teeth. The internal teeth on the spline are sometimes referred to as spline teeth. The external teeth on the flexspline are sometimes referred to as flexspline teeth. The transmission ratio is determined by the number of teeth. For example, if the spline is fixed, the reduction ratio of the flexspline output is: r h =-Zr / (Zg-Zr), where Zg is the number of teeth on the rigid spline and Zr is the number of teeth on the flex spline.

[0006] According to this formula, the transmission ratio is independent of the deformation. It can be any value as long as the gear teeth mesh and there is no interference. However, the deformation does affect the meshing performance and meshing quality.

[0007] The maximum deformation of the wave generator is ω0, and the modulus of the flexible wheel is m. Figure 2 As shown, when ω0=m, the flexspline pitch circle 201 is tangent to the rigid wheel pitch circle 301, and the trajectory of the flexspline has a peak shape (as shown in FIG. Figure 5As shown), the meshing center is at the long axis of the wave generator, where the meshing depth is the largest and the gear teeth have the smallest slip. At this point, the meshing quality between the flexible wheel and the rigid wheel is the best. Figure 3 As shown, when ω0<m, the motion trajectory of the flexible wheel has a blunt shape (such as Figure 6 As shown in the figure, the pitch circles of the flexspline and the rigid wheel do not touch. In this scheme, friction transmission cannot work, but gear transmission can work because the gear teeth have not lost their meshing. The gear teeth's meshing depth is reduced, forming meshing backlash. The meshing quality deteriorates because the slippage in the meshing increases, resulting in reduced efficiency and increased gear tooth wear. Figure 4 As shown, when ω0>m, the motion trajectory of the flexible wheel has a circular line shape (such as Figure 7 As shown), the meshing center point moves from the long axis of the wave generator to the opposite direction of the wave generator's rotation. In no-load transmission, the initial meshing is achieved on the meshing arc, and the sliding increases, which results in reduced efficiency and increased tooth wear.

[0008] To ensure good meshing quality between the flexspline and the rigid wheel at different reduction ratios, ω0 is preferably set to m. However, at low reduction ratios, the modulus m of the flexspline is large. If ω0=m is still selected, the maximum deformation ω0 of the flexspline will also be large, which will increase the stress on the flexspline and make it prone to damage. Furthermore, at high reduction ratios, the modulus m of the flexspline is small, and the stress on the flexspline itself is low. If ω0=m is still selected, although the flexspline has low stress, its load-bearing capacity is low and cannot match the load-bearing capacity at high reduction ratios, making the flexspline prone to overload and damage.

[0009] Therefore, how to ensure that the flexible wheel has good meshing quality and is not easily damaged under different reduction ratios has become a technical problem that technicians in this field urgently need to solve. Summary of the Invention

[0010] Therefore, the present invention provides a harmonic reduction mechanism, a harmonic reducer and a robot, the main technical problem to be solved is: how to ensure that the flexible wheel has good meshing quality and is not easily damaged under different reduction ratios.

[0011] In order to solve the above problems, the present invention provides a harmonic reduction mechanism, which includes a flexspline, a rigid pulley and a wave generator, wherein the flexspline is sleeved on the wave generator, and the rigid pulley is sleeved on the flexspline and meshes with the flexspline; the reduction ratio of the harmonic reduction mechanism is i, the maximum deformation of the wave generator is ω0, and the module of the flexspline is m;

[0012] Wherein, a*i+b≤ω0 / m≤a*i+c, a∈[0.002,0.004], b∈[0.6,0.7], c∈[0.8,1], and the units of ω0 and m are both millimeters;

[0013] When ω0<m, the flexspline and the rigid wheel are engaged with each other without backlash; when ω0>m, the flexspline and the rigid wheel are engaged with each other without interference.

[0014] In some embodiments, when i<80, 0.8≤ω0 / m<0.9.

[0015] In some embodiments, when 80≤i<100, 0.9≤ω0 / m<1.2.

[0016] In some embodiments, when 100≤i<120, 1.1≤ω0 / m<1.2.

[0017] In some embodiments, when 120≤i, 1.2≤ω0 / m<1.3.

[0018] In some embodiments, when ω0<m, the rigid wheel is cut by using a negative tool shift, and the shape of the teeth of the rigid wheel is adjusted so that the flexible wheel and the rigid wheel are engaged with each other without side clearance.

[0019] In some embodiments, when ω0>m, the tool is used to cut the rigid wheel with a positive displacement, and the gear tooth shape of the rigid wheel is adjusted to ensure non-interference meshing between the flexible wheel and the rigid wheel.

[0020] The present invention also provides a harmonic reducer, which may include any one of the harmonic reduction mechanisms described above.

[0021] The present invention also provides a robot, which may include the harmonic reducer described above.

[0022] The harmonic reduction mechanism, harmonic reducer and robot provided by the present invention have the following beneficial effects:

[0023] 1. It can ensure that under different reduction ratios, the flexible wheel has good meshing quality and is not prone to damage.

[0024] 2. When the reduction ratio i of the harmonic reduction mechanism is small, such as less than 80, ω0<m. Since the maximum deformation ω0 of the wave generator is small, the stress on the flexspline is reduced, which can improve the service life of the flexspline. In addition, by ensuring the backlash-free meshing between the flexspline and the rigid wheel, the backlash between the flexspline and the rigid wheel caused by ω0<m can also be eliminated. This ensures that the flexspline has good meshing quality and low stress at a small reduction ratio, making it less prone to damage.

[0025] 3. When the reduction ratio i of the harmonic reduction mechanism is large, for example, greater than 100, ω0>m. At this time, due to the small modulus m at a large reduction ratio i, the stress on the flexspline is inherently small. At this time, the maximum deformation ω0 of the flexspline can be appropriately increased to make ω0>m. The stress on the flexspline will increase slightly due to the increase in ω0, but the overall stress on the flexspline is still at a low level. In addition, the increase in ω0 can increase the load capacity of the flexspline, preventing the flexspline from being damaged due to excessive load capacity at a large transmission ratio. Among them, by ensuring non-interference meshing between the flexspline and the rigid wheel, the meshing interference between the flexspline and the rigid wheel caused by ω0>m is eliminated. In this way, the flexspline has better meshing quality at a large reduction ratio, and its load capacity is improved, making it less likely to be damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. The drawings described below are merely exemplary. Those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0027] Figure 1 It is a structural diagram of the harmonic reduction mechanism;

[0028] Figure 2 Schematic diagram of meshing of flex spline teeth and rigid spline teeth when ω0=m in the prior art;

[0029] Figure 3 Schematic diagram of meshing of flex spline teeth and rigid spline teeth when ω0<m in the prior art;

[0030] Figure 4 Schematic diagram of meshing of flex spline teeth and rigid spline teeth when ω0>m in the prior art;

[0031] Figure 5 The motion trajectory diagram of the flexspline relative to the rigid gear teeth when ω0=m in the prior art;

[0032] Figure 6 The motion trajectory diagram of the flex spline relative to the rigid spline teeth when ω0 < m in the prior art;

[0033] Figure 7 The motion trajectory diagram of the flex spline relative to the rigid spline teeth when ω0>m in the prior art;

[0034] Figure 8 Schematic diagram of meshing of the flexible spline teeth and the rigid spline teeth after adjusting the gear shape of the rigid spline teeth when ω0<m in the present invention;

[0035] Figure 9Schematic diagram of meshing of the flexible spline and the rigid spline after the gear shape of the rigid spline is adjusted when ω0>m in the present invention.

[0036] The accompanying drawings are:

[0037] 1. Wave generator; 2. Flexspline; 3. Rigid spline; 11. Cam; 12. Flexible bearing; 21. Flexspline teeth; 31. Rigid spline teeth; 201. Flexspline pitch circle; 301. Rigid spline pitch circle. DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0040] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0041] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0042] See also Figure 1 As shown, according to an embodiment of the present invention, a harmonic reduction mechanism is provided, which includes a flexspline 2, a rigid wheel 3 and a wave generator 1. The flexspline 2 is sleeved on the wave generator 1. The rigid wheel 3 is sleeved on the flexspline 2 and meshed with the flexspline 2. Specifically, the flexspline 2 has external teeth, and the rigid wheel 3 has internal teeth. The internal teeth on the rigid wheel 3 are sometimes also referred to as rigid wheel teeth 31. The external teeth on the flexspline 2 are sometimes also referred to as flexspline teeth 21. The flexspline teeth 21 of the flexspline are meshed with the rigid wheel teeth 31 of the rigid wheel. The wave generator 1 may include a cam 11 and a flexible bearing 12 sleeved on the cam 11. The wave generator 1 is sleeved and mounted on the flexspline 2 through the flexible bearing 12.

[0043] The reduction ratio of the harmonic reduction mechanism is i, the maximum deformation of the wave generator 1 is ω0, the module of the flexspline 2 is m, and the units of ω0 and m are both millimeters.

[0044] Where a*i+b≤ω0 / m≤a*i+c, a∈[0.002,0.004], b∈[0.6,0.7], c∈[0.8,1]. When ω0<m, there is backlash-free meshing between flexspline 2 and rigid wheel 3. When ω0>m, there is interference-free meshing between flexspline 2 and rigid wheel 3. "Backlash-free meshing" here means there is no backlash at the meshing point between flexspline 2 and rigid wheel 3. "Interference-free meshing" means there is no interference at the meshing point between flexspline 2 and rigid wheel 3.

[0045] In the above example, according to the above formula, when the reduction ratio i of the harmonic reduction mechanism is small, for example, less than 80, at this time ω0<m, the maximum deformation ω0 of the wave generator 1 is small, so the stress on the flexible spline 2 is small, which can improve the service life of the flexible spline 2. In addition, by making the flexible spline 2 and the rigid spline 3 mesh without backlash, the meshing backlash between the flexible spline 2 and the rigid spline 3 caused by ω0<m can also be eliminated (such as Figure 8 As shown in FIG, the flexible wheel 2 has good meshing quality at a small reduction ratio and has low stress, making it less prone to damage.

[0046] According to the above formula, when the reduction ratio i of the harmonic reduction mechanism is large, for example, greater than 100, ω0>m. At this time, due to the small modulus m at a large reduction ratio i, the stress on the flexible wheel 2 is itself small. At this time, the maximum deformation ω0 of the flexible wheel 2 can be appropriately increased to make ω0>m. The stress on the flexible wheel 2 will increase slightly due to the increase in ω0, but the overall stress on the flexible wheel 2 is still at a low level. In addition, the increase in ω0 can increase the load-bearing capacity of the flexible wheel 2, preventing the flexible wheel 2 from being damaged due to excessive load-bearing capacity at a large transmission ratio. Among them, by making the meshing between the flexible wheel 2 and the rigid wheel 3 non-interfering, the meshing interference between the flexible wheel 2 and the rigid wheel 3 caused by ω0>m is eliminated (such as Figure 9 As shown), the flexible wheel 2 has better meshing quality at a large reduction ratio, and its load-bearing capacity is improved, making it less likely to be damaged.

[0047] In summary, through the above-mentioned settings, it can be ensured that under different reduction ratios, the flexible wheel 2 has good meshing quality and is not easily damaged.

[0048] In order to achieve the effect of free backlash meshing between the flexible spline 2 and the rigid spline 3 when ω0<m, it is preferred that Figure 8 As shown in FIG, when ω0<m, the tool negative displacement can be used to cut the rigid wheel 3 and adjust the gear tooth shape of the rigid wheel 3 so that the flexible wheel 2 and the rigid wheel 3 can be meshed without side clearance.

[0049] In the above example, by adjusting the tooth profile of the rigid spline 3 , the backlash between the flexible spline 2 and the rigid spline 3 caused by ω0<m can be eliminated.

[0050] Figure 8 A schematic diagram of the meshing of the rigid spline 3 and the flexspline 2 is shown after adjusting the tooth profile of the rigid spline 3 when ω0 < m. As can be seen from the figure, there is a gap between the flexspline pitch circle 201 and the rigid spline pitch circle 301, but there is no meshing backlash between the flexspline teeth 21 and the rigid spline teeth 31.

[0051] It should be noted that when ω0<m, after adjusting the tooth profile of the rigid wheel 3 , the tooth groove depth of the rigid wheel 3 is smaller than the conventional processing depth, thereby eliminating the side clearance between the rigid wheel 3 and the flexible wheel 2 .

[0052] In order to achieve the effect of non-interference meshing between the flexible spline 2 and the rigid spline 3 when ω0>m, it is preferred that Figure 9 As shown, when ω0>m, the tool can be used to cut the rigid wheel 3 with a positive displacement, and the gear shape of the rigid wheel 3 can be adjusted to ensure non-interference meshing between the flexible wheel 2 and the rigid wheel 3.

[0053] In the above example, by adjusting the tooth profile of the rigid spline 3 , the meshing interference between the flexible spline 2 and the rigid spline 3 caused by ω0>m can be eliminated.

[0054] Figure 9 A schematic diagram shows the meshing of the rigid spline 3 and the flexspline 2 after adjusting the tooth profile of the rigid spline 3 when ω0>m. As can be seen from the figure, the flexspline pitch circle 201 is closer to the rigid spline 3 than the rigid spline pitch circle 301, but there is no meshing interference between the flexspline teeth 21 and the rigid spline teeth 31.

[0055] It should be noted that when ω0>m, after adjusting the tooth profile of the rigid wheel 3, the tooth groove depth of the rigid wheel 3 is greater than the conventional processing depth, thereby eliminating the meshing interference between the rigid wheel 3 and the flexible wheel 2.

[0056] In some embodiments, when i < 80, 0.8 ≤ ω0 / m < 0.9. Thus, when the reduction ratio i is small, ω0 < m, which reduces the stress on the flexspline 2 and improves the service life of the flexspline 2. Furthermore, when 0.8 ≤ ω0 / m < 0.9, the value of ω0 is within an optimal range. Thus, the flexspline 2 not only has low stress but also has a relatively moderate load-bearing capacity.

[0057] In some embodiments, when 80≤i<100, 0.9≤ω0 / m<1.2. Thus, when the reduction ratio i is medium, ω0 and m are substantially equal, so that the stress on the flexspline 2 is small and the bearing capacity is relatively moderate.

[0058] In some embodiments, when 100≤i<120, 1.1≤ω0 / m<1.2. Thus, when the reduction ratio i is large, ω0>m, so that the stress on the flexible pulley 2 is small and the flexible pulley 2 has a relatively large load-bearing capacity.

[0059] In some embodiments, when 120≤i, 1.2≤ω0 / m<1.3. Thus, when the reduction ratio i is large, ω0>m, which reduces the stress on the flexible pulley 2 and provides a relatively larger load-bearing capacity.

[0060] The present invention further provides a harmonic reducer, which may include any of the above-mentioned harmonic reduction mechanisms. Since the harmonic reducer adopts the above-mentioned harmonic reduction mechanism, it can ensure that the flexspline 2 has good meshing quality and is not easily damaged under different reduction ratios.

[0061] The present invention further provides a robot, which may include the above-mentioned harmonic reducer. Since the robot adopts the above-mentioned harmonic reducer, it can ensure that the flexible wheel 2 has good meshing quality and is not easily damaged under different reduction ratios.

[0062] It is easy for those skilled in the art to understand that, under the premise of no conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and variations without departing from the technical principles of the present invention, and such improvements and variations shall also be considered within the scope of protection of the present invention.

Claims

1. A harmonic reduction mechanism, characterized in that: The invention comprises a flexible wheel (2), a rigid wheel (3) and a wave generator (1), wherein the flexible wheel (2) is sleeved on the wave generator (1), and the rigid wheel (3) is sleeved on the flexible wheel (2) and meshed with the flexible wheel (2); the reduction ratio of the harmonic reduction mechanism is i, the maximum deformation of the wave generator (1) is ω0, and the module of the flexible wheel (2) is m; Wherein, a*i+b≤ω0 / m≤a*i+c, a∈[0.002,0.004], b∈[0.6,0.7], c∈[0.8,1], and the units of ω0 and m are both millimeters; When ω0<m, the flexible spline (2) and the rigid spline (3) are engaged with each other without backlash; when ω0>m, the flexible spline (2) and the rigid spline (3) are engaged with each other without interference.

2. The harmonic reduction mechanism according to claim 1, characterized in that: When i<80, 0.8≤ω0 / m<0.

9.

3. The harmonic reduction mechanism according to claim 1, characterized in that: When 80≤i<100, 0.9≤ω0 / m<1.

2.

4. The harmonic reduction mechanism according to claim 1, characterized in that: When 100≤i<120, 1.1≤ω0 / m<1.

2.

5. The harmonic reduction mechanism according to claim 1, characterized in that: When 120≤i, 1.2≤ω0 / m<1.

3.

6. The harmonic reduction mechanism according to any one of claims 1 to 5, characterized in that: When ω0<m, the tool negative displacement is used to cut the rigid wheel (3), and the gear tooth shape of the rigid wheel (3) is adjusted so that the flexible wheel (2) and the rigid wheel (3) are meshed without side clearance.

7. The harmonic reduction mechanism according to any one of claims 1 to 5, characterized in that: When ω0>m, the tool is used to cut the rigid wheel (3) by positive displacement, and the gear tooth shape of the rigid wheel (3) is adjusted to ensure non-interference meshing between the flexible wheel (2) and the rigid wheel (3).

8. A harmonic reducer, characterized in that: The invention comprises the harmonic reduction mechanism according to any one of claims 1 to 7.

9. A robot, characterized in that: The invention comprises the harmonic reducer as claimed in claim 8.

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