Waveform high-compliance harmonic reducer retainer

Abstract

The application discloses a wave-shaped high-flexibility harmonic reducer retainer, which comprises a retainer body with a wave crest section and a wave trough section, and the wave crest section and the wave trough section are arranged in a spaced and circumferentially continuous mode on the retainer body; the rising wave section and the falling wave section of the wave crest section and the wave trough section constitute window beams, the adjacent window beams form pockets for accommodating rolling bodies, and the rolling bodies installed in the corresponding pockets of the wave crest section and the wave trough section are located on a uniform height plane; during a periodic elliptical deformation process of the retainer, the wave crest section and the wave trough section can adaptively change the wavelength to uniformly disperse stress, reduce stress concentration, improve the fatigue life of the retainer, and the flexible bearing generates a periodic elliptical deformation, and the retainer synchronously deforms to adapt to the periodic elliptical deformation; the wave crest section and the wave trough section of the wave-shaped high-flexibility retainer can adaptively change the wavelength, that is, the wave-shaped elongation is used to adjust the size of the wave-shaped high-flexibility retainer, so that the deformation resistance is reduced, the overall deformation of the retainer is more smooth, and the local stress concentration caused by rigid constraint is reduced.

Description

Technical Field

[0001] This application belongs to the field of harmonic reducer cages, and particularly relates to a high-flexibility waveform harmonic reducer cage. Background Technology

[0002] Harmonic reducers, as a crucial transmission device, are widely used in numerous industrial fields, especially in components such as robot joints. Among the core components of harmonic reducers, flexible bearings play a vital role. They not only transmit motion and power but also adapt to the unique transmission method of harmonic reducers through their elastic deformation. The cage of the harmonic reducer, as an important component of the flexible bearing, directly affects the operating performance and service life of the entire bearing and even the harmonic reducer.

[0003] In the actual operation of harmonic reducers, the wave generator is a key component that triggers a series of mechanical motion changes. When the wave generator operates, it causes the flexible bearing to undergo specific periodic elliptical deformation. However, current harmonic reducer cage designs generally suffer from an unavoidable problem: they all include a complete end ring structure. While the end ring plays a role in enhancing structural stability and guiding the rolling elements to some extent, it faces severe fatigue life issues in actual use. During periodic elliptical deformation, the bearing shape continuously changes, and the connection between the end ring and the beam experiences significant alternating stress. This stress concentration accelerates material fatigue damage. Therefore, existing technology needs further improvement and enhancement. Summary of the Invention

[0004] This invention provides a high-flexibility harmonic reducer cage, which solves the problem of stress concentration and material fatigue damage at the connection between the end ring and the window beam of the existing harmonic reducer cage under periodic elliptical deformation, resulting in a low fatigue life of the overall cage.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-flexibility harmonic reducer cage includes a cage body having crest sections and trough sections, wherein the crest sections and trough sections on the cage body are spaced apart and circumferentially continuous.

[0007] The rising and falling segments of the crest and trough segments form window beams, and pockets for accommodating rolling elements are formed between adjacent window beams. The rolling elements installed in the corresponding pockets of the crest and trough segments are located on a plane of uniform height.

[0008] During the periodic elliptical deformation of the cage, the crest and trough segments can adaptively change the wavelength to uniformly distribute stress, reduce stress concentration, and improve the fatigue life of the cage.

[0009] In a preferred embodiment, the pocket includes a first pocket with a lower opening and a second pocket with an upper opening. The first pocket and the second pocket have opposing locking points near the opening side. When the wavelength increases and the opening increases, the locking points can prevent the rolling element from falling from the opening side.

[0010] In a preferred implementation, the limiting locking point is the curved portion of the window beam facing the pocket.

[0011] In a preferred implementation, the limiting locking point is provided with a magnetic attractor, and the magnetic attractors in adjacent limiting locking points have opposite magnetic properties.

[0012] In a preferred implementation, the rising band and the falling band are connected by a connecting segment. The connecting segment, the rising band, and the falling band are aligned with the contour of the rolling element facing the pocket surface, and the connecting segment is planar away from the pocket surface.

[0013] In the preferred implementation, the rising band, the falling band, and the connecting segment are integrally formed, and the three have the same wall thickness and the connecting position has a rounded corner transition.

[0014] In the preferred implementation, the wavelengths of the peak and trough segments are the same;

[0015] The wavelengths of the crest and trough segments may be different. The wavelength of the crest / trough segment is n times that of the trough / crest. The long crest / trough segment has n-1 dividing beams to create pockets that are compatible with the short trough / crest segments.

[0016] In a preferred implementation, the crest and trough segments are arc-shaped, with inner pockets for accommodating ball rollers; or the crest and trough segments are rectangular, with inner pockets for accommodating cylindrical rollers.

[0017] In the preferred implementation, the wave heights of the crest and trough segments are equal.

[0018] The above structure has the following beneficial effects:

[0019] 1. The waveform high flexibility harmonic reducer cage of this application is composed of circumferentially continuous peak and trough sections, with rising and falling sections forming a smooth transition window beam. This structure makes the stress evenly distributed along the waveform path. During the operation of the harmonic reducer, the elliptical deformation of the flexible bearing will cause the periodic deformation of the cage, while the continuous waveform structure can disperse the deformation stress to the entire waveform surface and avoid local stress overload.

[0020] 2. The waveform high-flexibility harmonic reducer cage of this application has a dynamic adjustment of the wavelength when the wave generator drives the flexible bearing to produce periodic elliptical deformation. The spacing between the wave crest and the wave trough increases, and the adaptive deformation and the connection design that eliminates the geometric change zone make the stress uniformly transmitted along the waveform surface, avoiding premature fatigue damage in local areas.

[0021] 3. The high-flexibility harmonic reducer cage of this application has an ascending wave segment and a descending wave segment connected by a connecting segment. The connecting segment, the ascending wave segment, and the descending wave segment are aligned with the pocket surface to adapt to the contour of the rolling element, ensuring that the pocket surface and the rolling element surface form a surface contact rather than a point contact. When the rolling element moves, the contact stress distribution is more uniform, avoiding surface fatigue caused by stress concentration. The connecting segment is set as a planar structure away from the pocket surface, which can directly reduce the axial height of the cage.

[0022] 4. The high-flexibility harmonic reducer cage of this application has micro-magnets embedded inside the limiting locking points, and the magnetic attractors of adjacent locking points have opposite polarities. When the cage is in its natural state, a reasonable gap is maintained between the magnetic attractors. When the wave generator drives the flexible bearing to deform, the change in the cage wavelength causes the limiting locking point spacing to adjust. The increase in wavelength increases the limiting locking point spacing. During the opening recovery stage, the wavelength shortens, the limiting locking point spacing decreases, and the attraction between the magnetic attractors is linearly enhanced. The attraction provides an auxiliary restoring force for the cage, accelerating its return to its shape from the deformed state and reducing the accumulation of plastic deformation. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 A schematic diagram illustrating a first embodiment of the waveform high-flexibility harmonic reducer cage of this application is shown.

[0025] Figure 2 The illustration shows a schematic implementation diagram of a first embodiment of the waveform high-flexibility harmonic reducer cage of this application, in which a partition beam is provided;

[0026] Figure 3 A schematic diagram illustrating a second embodiment of the waveform high-flexibility harmonic reducer cage of this application is shown.

[0027] Figure 4 The illustration shows a schematic implementation diagram of a second embodiment of the waveform high-flexibility harmonic reducer cage of this application, in which a partition beam is provided;

[0028] Label Explanation:

[0029] 10. Crest section; 100. Connecting section; 11. Trough section; 12. Window beam; 120. Rising wave section; 1201. Limiting locking point; 121. Falling wave section; 13. Pocket; 130. First pocket; 131. Second pocket; 14. Dividing beam. Detailed Implementation

[0030] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit and scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0031] The present invention will now be described with reference to the accompanying drawings.

[0032] The connection between the intact end ring of a traditional retainer and the window sill is a high-stress concentration area. During periodic elliptical deformation, alternating stress leads to material fatigue fracture. To address this problem, the specific solution adopted in this application is as follows:

[0033] like Figure 1-4 As shown, the present invention provides a cage for a high-flexibility harmonic reducer, including a cage body having a crest section 10 and a trough section 11, wherein the crest sections and trough sections on the cage body are spaced apart and circumferentially continuous.

[0034] The rising wave 120 and falling wave 121 of the crest and trough segments form a window beam 12, and a pocket 13 for accommodating the rolling element is formed between adjacent window beams. The rolling elements installed in the corresponding pockets of the crest and trough segments are located on a plane of the same height.

[0035] During the periodic elliptical deformation of the cage, the crest and trough segments can adaptively change the wavelength to uniformly distribute stress, reduce stress concentration, and improve the fatigue life of the cage.

[0036] The high-flexibility harmonic reducer cage of this application is composed of circumferentially continuous crest and trough sections, with rising and falling sections forming a smooth transition beam. This structure ensures uniform stress distribution along the waveform path. During the operation of the harmonic reducer, the elliptical deformation of the flexible bearing can cause periodic deformation of the cage. The continuous waveform structure disperses the deformation stress across the entire waveform surface, avoiding localized stress overload. The rolling elements installed in the corresponding pockets of the crest and trough sections are located at the same height plane, ensuring uniform distribution of contact stress between the rolling elements and the raceway.

[0037] Driven by the wave generator, the flexible bearing produces periodic elliptical deformation, and the cage needs to deform synchronously to adapt. The peak and trough sections of the high-flexibility waveform cage can adaptively change the wavelength, that is, adjust its own size by waveform elongation, thereby reducing deformation resistance. The overall deformation of the cage becomes smoother, reducing local stress concentration caused by rigid constraints.

[0038] Durability tests conducted on the robot joint harmonic reducer showed that the high-flexibility waveform cage did not crack even after exceeding the fatigue limit of the traditional cage, indicating that the fatigue cycle count of the high-flexibility waveform cage is greatly improved.

[0039] This application can be realized through precision injection molding or 3D printing, achieving high manufacturing precision while ensuring the consistency of waveform parameters.

[0040] See Figure 1 and Figure 4 The wave cage has alternating crests and troughs to form two types of pockets: a first pocket 130 with a lower opening and a second pocket 131 with an upper opening. To ensure that the centers of all rolling elements are located on the same height plane and that the contact stress between the rolling elements and the inner and outer raceways is evenly distributed, the first and second pockets have relative limiting locking points near the opening side. When the wave generator drives the flexible bearing to produce periodic elliptical deformation, the wavelength of the cage will be dynamically adjusted: the distance between the crests and troughs increases, and the pocket opening expands (the opening width increases). When the opening expands, the rolling elements tend to fall outward under the action of centrifugal force or inertial force. The limiting locking point 1201 prevents them from falling out by blocking them.

[0041] Specifically, the limiting locking point is the curved part of the window beam facing the pocket. The edge of the locking point is designed with rounded corners to avoid stress concentration and reduce impact load.

[0042] Traditional cages rely solely on the elastic recovery of material deformation, which is prone to plastic deformation hysteresis under high-frequency periodic deformation, leading to residual stress and fatigue crack initiation. In a preferred embodiment of this invention, each limiting locking point 1201 is embedded with a micro-magnet, with the magnetic attractors of adjacent locking points having opposite polarities. When the cage is in its natural state, a reasonable gap is maintained between the magnetic attractors. When the wave generator drives the flexible bearing to deform, the change in cage wavelength causes an adjustment in the spacing between the limiting locking points. A longer wavelength increases the spacing, while a shorter wavelength decreases the spacing during the opening recovery phase, linearly enhancing the attraction between the magnetic attractors. This attraction provides auxiliary restoring force to the cage, accelerating its return to its deformed shape and reducing the accumulation of plastic deformation. It is important to note that the rolling elements are made of non-magnetic material; otherwise, magnetic field interference could lead to transmission failure.

[0043] In a preferred embodiment of this application, the rising wave segment and the falling wave segment are connected by a connecting segment 100. The connecting segment, the rising wave segment, and the falling wave segment are aligned with the contour of the rolling element facing the pocket surface, ensuring that the pocket surface and the rolling element surface form surface contact rather than point contact. When the rolling element moves, the contact stress distribution is more uniform, avoiding surface fatigue caused by stress concentration. The connecting segment is set as a planar structure away from the pocket surface, which can directly reduce the axial height of the cage. Traditional crest-trough connection structures (such as sine curves) will produce geometric abrupt changes at the crest and trough, leading to stress concentration. In this application, the rising wave segment, the falling wave segment, and the connecting segment are integrally formed, all three having the same wall thickness and rounded transitions at the connection positions. Through rounded transitions, stress concentration is reduced and fatigue life is improved.

[0044] In a preferred embodiment of this application, when the number of rolling elements N is even (e.g., N = 8, 12), the wavelengths of the crest and trough segments are equal, and the rolling elements are evenly distributed between the crests and troughs. When the number of rolling elements N is odd (e.g., N = 7, 9), an alternating structure of long and short wavelengths is required, with different wavelengths for the crest and trough segments. The wavelength of the crest / trough segment is n times that of the trough / crest segment. The long crest / trough segment has n-1 dividing beams, creating pockets that match the short trough / crest segments. See, for example... Figure 2 and Figure 4 It features a long wave crest section containing a dividing beam 14, which divides the area into two pockets; the other sections consist of seventeen independent pockets in total, including short wave crests and troughs, providing a total of 19 rolling element bearing positions. This design is suitable for scenarios where the number of rolling elements needs to be flexibly adjusted.

[0045] As the first preferred embodiment of this application, see [link to application]. Figure 1 and Figure 2 The crests and troughs are arc-shaped, with inner pockets to accommodate the balls and rollers. The arc-shaped crests (convex surfaces) and troughs (concave surfaces) transition through continuous curvature. The arc-shaped surfaces guide the balls / rollers to roll smoothly in the wave field, reducing impact loads. The relationship between the arc radius R of the crests and troughs and the ball diameter D is: R≈(1.2~1.5)D, ensuring that the balls do not jump at the crests and troughs. This significantly improves the stress uniformity, dynamic balance, and lubrication efficiency of the rolling element system.

[0046] As a second preferred embodiment of this application, see [link to previous document]. Figure 3 and Figure 4, the crest segments and the trough segments are rectangular, and the pockets therein are configured to receive cylindrical rollers. The rectangular crest segment is composed of vertical side walls and a horizontal top surface, and the trough segment is composed of vertical side walls and a horizontal bottom surface, forming a "mouth"-shaped cross section. The pocket is located in the rectangular trough segment and adopts a semi-cylindrical groove structure: the radius R = the diameter D of the cylindrical roller ± 0.05mm (to ensure free rolling of the roller); the rectangular structure is easy to machine, and the cost is 30% to 50% lower than that of the arc-shaped structure; the vertical side walls can bear a relatively large radial force, but there is stress concentration at the right-angle transition, so a rounded corner can be provided in the right-angle transition region, the limit locking point can be a protrusion on the side of the window beam facing the pocket, and the height position of the protrusion is adapted to the crest point and the trough point.

[0047] As a preferred embodiment of the present application, the crest segments and the trough segments have equal wave heights. When the heights of the crests and the troughs are equal (H1=H2=H), the structural mass distribution is symmetrical about the central axis, which can eliminate the eccentricity of the inertial force under dynamic load: when the wave heights are equal, the path of stress transmission from the crests to the troughs is in smooth transition, which improves the stress uniformity.

[0048] Parts not described in the present invention can be implemented by adopting or referring to the existing technologies.

[0049] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various changes or substitutions within the technical scope disclosed by the present invention, which shall all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A cage for a high-flexibility harmonic reducer, characterized in that, Includes a cage body with crest sections and trough sections, wherein the crest sections and trough sections on the cage body are spaced apart and circumferentially continuous; The rising and falling segments of the crest and trough segments form window beams, and pockets for accommodating rolling elements are formed between adjacent window beams. The rolling elements installed in the corresponding pockets of the crest and trough segments are located on a plane of uniform height. During the periodic elliptical deformation of the cage, the crest and trough segments can adaptively change the wavelength to uniformly distribute stress, reduce stress concentration, and improve the fatigue life of the cage. The pocket includes a first pocket with a lower opening and a second pocket with an upper opening. The first pocket and the second pocket have opposing locking points near the opening side. When the wavelength increases and the opening increases, the locking points can prevent the rolling element from falling from the opening side. The limiting lock point is equipped with a magnetic attractor, and the magnetic attractors in adjacent limiting lock points have opposite magnetic properties.

2. The waveform high-flexibility harmonic reducer cage according to claim 1, characterized in that, The limiting locking point is the curved part of the window beam facing the pocket.

3. The waveform high-flexibility harmonic reducer cage according to claim 1, characterized in that, The rising wave band and the falling wave band are connected by a connecting section. The connecting section, the rising wave band, and the falling wave band are aligned with the contour of the rolling element and face away from the pocket surface. The connecting section is a plane facing away from the pocket surface.

4. The waveform high-flexibility harmonic reducer cage according to claim 3, characterized in that, The rising band, falling band, and connecting section are integrally formed, with all three having the same wall thickness and rounded corners at the connection points.

5. The waveform high-flexibility harmonic reducer cage according to claim 1, characterized in that, When the number of rolling elements N is even, the wavelengths of two adjacent peaks and two adjacent troughs are equal. The number of rolling elements N is odd, and there are long wave crests or long wave troughs. The long wave crests or long wave troughs are equipped with dividing beams, and the dividing beams divide at least two pockets.

6. The waveform high-flexibility harmonic reducer cage according to claim 1, characterized in that, The crest and trough sections are arc-shaped, with inner pockets for accommodating ball bearings; or the crest and trough sections are rectangular, with inner pockets for accommodating cylindrical rollers.

7. The waveform high-flexibility harmonic reducer cage according to claim 1, characterized in that, The wave heights of the crest and trough segments are equal.

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