Gearbox and harmonic reducer

Abstract

The present application relates to a rigid wheel and a harmonic reducer. The rigid wheel comprises a first wheel body, which includes a first shaft portion and a second shaft portion continuously distributed along its axial direction. The second wheel body is located on the outer periphery of the first shaft portion. The second wheel body is provided with a first recessed portion enclosed by the outer wall of the second shaft portion on the side facing the second shaft portion. The outer wall of the second shaft portion is provided with a second recessed portion, which is arranged adjacent to the first recessed portion. The rigid wheel and harmonic reducer can avoid problems such as abnormal performance parameters such as rigidity and noise, and reduced lifespan of the harmonic reducer caused by abnormal meshing between the rigid wheel and the flexspline.

Description

Technical Field

[0001] The present application relates to the technical field of speed reducers, and in particular to a rigid wheel and harmonic speed reducer. Background Art

[0002] Harmonic reducers offer numerous advantages, including high transmission accuracy, a large speed ratio, a compact size, a simple structure, and a wide range of applications. They consist of three basic components: a rigid wheel, a flexwheel, and a wave generator. The operating process typically involves the rigid wheel being stationary while the wave generator rotates, forcing the flexwheel to elastically deform, causing the teeth of the flexwheel to mesh with those of the rigid wheel, thereby achieving transmission. Therefore, the higher the precision of the rigid wheel, the more effectively it can mesh with the rigid wheel during elastic deformation, avoiding problems such as abnormal wear and reducer grease leakage caused by improper meshing.

[0003] To ensure the precision of the rigid wheel, the foundation structure and sealing ring groove are usually turned first during the processing of the rigid wheel, and then the rigid wheel is ground. Due to process limitations, during mass production, due to wear of the grinding wheel radius, it is very easy for the rigid wheel to be improperly processed and have steps. During the assembly of the reducer, the existing steps will affect the assembly accuracy and sealing, resulting in seal failure and reducer grease leakage. In addition, the teeth of the rigid wheel and the flexspline will be tilted, which is prone to abnormal meshing and affects the rigidity of the reducer. Summary of the Invention

[0004] The purpose of this application is to provide a rigid wheel and a harmonic reducer to avoid the problems of abnormal performance parameters such as rigidity and noise of the harmonic reducer and reduced life caused by abnormal meshing between the rigid wheel and the flexible wheel.

[0005] To this end, in a first aspect, an embodiment of the present application provides a rigid wheel, the rigid wheel comprising:

[0006] The first wheel body includes a first shaft portion and a second shaft portion continuously distributed along the axial direction of the first wheel body.

[0007] The second wheel body is located on the outer peripheral side of the first shaft portion. The second wheel body is provided with a first recessed portion on the side facing the second shaft portion, which is surrounded by the outer side wall of the second shaft portion. A second recessed portion is provided on the outer side wall of the second shaft portion, and the second recessed portion is arranged close to the first recessed portion.

[0008] In a possible implementation, the second recessed portion is annularly provided on the outer side wall of the second shaft portion along the axial direction.

[0009] The second recessed portion is configured as an arcuate surface recessed inwardly from the outer side wall along the radial direction, and the axial direction intersects with the radial direction.

[0010] In a possible implementation, the second recessed portion is annularly provided on the outer side wall of the second shaft portion along the axial direction.

[0011] The second recessed portion has a bottom wall and side walls, and the bottom wall and the side walls are smoothly connected.

[0012] In a possible implementation, a mating surface is provided on a side of the second wheel body facing the second shaft portion, and the first recessed portion is located on the mating surface.

[0013] Along the radial direction, the extension line of the first straight line formed by the mating surface has an intersection with the second shaft portion, and the intersection is located inside the second recessed portion, or the intersection is located outside the second recessed portion, and the second recessed portion is located on the side of the intersection away from the first shaft portion.

[0014] In one possible implementation, the intersection is located in the second recessed portion, and along the axial direction, the edge of the second recessed portion facing the first shaft portion has a first preset distance P1 to the intersection, and the first recessed portion has a preset depth H1, P1≤1 / 3×H1.

[0015] In one possible implementation, the intersection is located outside the second recessed portion, and along the axial direction, the edge of the second recessed portion facing the first shaft portion intersects with the intersection, or the edge of the second recessed portion facing the first shaft portion has a second preset distance from the intersection.

[0016] In a possible implementation, the inner sidewall of the second shaft portion is provided with a plurality of gear teeth continuously arranged along the circumferential direction, and along the radial direction, a first distance δ is present between the tooth roots of the gear teeth and the outer sidewall of the second shaft portion.

[0017] Along the radial direction, the maximum depth of the second recessed portion at the second shaft portion is a second distance Y3, where Y3 ≤ 1 / 4×δ.

[0018] In one possible implementation, the inner sidewall of the second shaft portion is provided with a plurality of gear teeth continuously arranged along the circumferential direction. In a cross section passing through the axis of the first wheel body, the contour shape of the second recessed portion is obtained according to a contour trajectory equation with the coordinate origin being O.

[0019] The contour trajectory equation is:

[0020] x=r(k×t-sint)

[0021] y = r(k-cost);

[0022] x is the abscissa, y is the ordinate, h×10 / D≤r≤h / δ, (h-δ) / (D / 2)≤k≤(h+δ) / (D / 2), -π≤t≤π, h is the full tooth depth of the gear tooth, D is the pitch circle diameter of the gear tooth, δ is the thickness of the gear tooth from the root to the outer side wall of the second shaft portion, t is the angular variable of the gear tooth profile, k is the proportional coefficient, and r is the base circle radius;

[0023] Among them, the straight line formed by the outer side wall of the second shaft portion is translated outward along the radial direction by a third distance Y2, and the second wheel body is provided with a mating surface on the side facing the first shaft portion. The straight line formed by the mating surface is translated along the axial direction toward the second shaft portion by a fourth distance Y1, and the intersection of the two translated straight lines serves as the coordinate origin O, 0≤Y1≤0.25×r, 0≤Y2≤0.5×r.

[0024] In a possible implementation, 0.1 mm ≤ r ≤ 0.5 mm, and -0.01 ≤ k ≤ 0.05.

[0025] In a second aspect, an embodiment of the present application provides a harmonic reducer, comprising a rigid wheel, wherein the rigid wheel is the rigid wheel described above.

[0026] According to the embodiment of the present application, the rigid wheel and harmonic reducer provided by the embodiment of the present application have a second recessed portion provided on the outer wall of the second shaft portion, and the second recessed portion is provided at a position close to the first recessed portion, so that the second recessed portion can avoid the problem of steps on the rigid wheel during turning. At the same time, the second recessed portion provided at this position does not affect the matching accuracy of the rigid wheel and the rigid wheel bearing during assembly. When the rigid wheel and the rigid wheel bearing are matched, the matching surfaces of the two can fit well, the grease in the first recessed portion will not leak, and a good sealing effect is achieved. In addition, in the harmonic reducer, the second shaft portion is mainly involved in the meshing with the flexspline, and the flexspline sleeve is sleeved in the second shaft portion, and the two are meshed. The second recessed portion provided at the position of the second shaft portion close to the first recessed portion can minimize the impact on the strength of the rigid wheel, ensure that the rigid wheel and the flexspline do not engage abnormally during use, ensure the stability of the performance parameters such as the rigidity and noise of the harmonic reducer, and improve the service life of the harmonic reducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In addition, in the drawings, the same reference numerals are used for the same components, and the drawings are not drawn according to the actual scale.

[0028] Figure 1 A schematic diagram of a cross-sectional structure of a rigid wheel provided in an embodiment of the present application is shown, wherein the direction indicated by arrow L is the axial direction, and the direction indicated by arrow W is the radial direction;

[0029] Figure 2 A partially enlarged view of a rigid wheel provided in an embodiment of the present application is shown, wherein the direction indicated by arrow L is the axial direction, and the direction indicated by arrow W is the radial direction;

[0030] Figure 3 Show Figure 2 The enlarged view of part N in the middle, wherein the direction indicated by arrow L is the axial direction, and the direction indicated by arrow W is the radial direction;

[0031] Figure 4 A schematic diagram showing a contour trajectory M of a second recessed portion provided in a rigid wheel according to an embodiment of the present application is shown, wherein the direction indicated by arrow L is the axial direction, and the direction indicated by arrow W is the radial direction;

[0032] Figure 5 A cross-sectional view of a harmonic reducer provided in an embodiment of the present application is shown, wherein the direction indicated by arrow L is the axial direction, and the direction indicated by arrow W is the radial direction.

[0033] Description of reference numerals:

[0034] 1. Rigid wheel; 11. Second wheel body; 111. Mating surface; 111a. Intersection; 12. First wheel body; 12A. First shaft; 12B. Second shaft; 121-Second recess; 122-Gear teeth; 13-First recess; 14-Screw hole; 2. Rigid bearing; 3. Flexspline; 4. Wave generator. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] Figure 1 A schematic diagram of the cross-sectional structure of a rigid wheel provided in an embodiment of the present application is shown. Figure 2 The figure shows a partially enlarged view of a rigid wheel provided in an embodiment of the present application.

[0037] See also Figure 1 and Figure 2The embodiment of the present application provides a rigid wheel for use in a harmonic reducer. The rigid wheel 1 includes a first wheel body 12 and a second wheel body 11. The first wheel body 12 includes a first shaft portion 12A and a second shaft portion 12B continuously distributed along its own axial direction L. The second wheel body 11 is located on the outer peripheral side of the first shaft portion 12A. The first wheel body 12 and the second wheel body 11 form an annular structure with a shoulder. Along the axial direction L, the side of the second wheel body 11 facing the second shaft portion 12B is provided with a first recessed portion 13 formed by enclosing the outer side wall of the second shaft portion 12B. The outer side wall of the second shaft portion 12B is provided with a second recessed portion 121, and the second recessed portion 121 is arranged near the first recessed portion 13. It is understandable that, in order to facilitate the description of the specific structure of the present application, the rigid wheel 1 is divided into different parts such as the first shaft portion 12A, the second shaft portion 12B, and the second wheel body 11 for description, but this does not mean that the various parts are independent entities. In order to ensure the rigidity of the rigid wheel 1, the first wheel body 12 and the second wheel body 11 can be an integrally formed structure, such as casting, turning, etc., so that the second shaft portion 12B becomes an annular protrusion structure in the rigid wheel 1, which is not described in detail here.

[0038] Optionally, the first recessed portion 13 is arranged in an annular manner around the circumference of the second shaft portion 12B. In the rigid wheel 1, the first recessed portion 13 is used as a sealing groove for accommodating a sealing ring, grease, etc. for assembly with the rigid bearing. The size and shape of the first recessed portion 13 are not specifically limited herein. For example, the first recessed portion 13 can be a U-shaped groove with a U-shaped cross-section, as long as it can ensure a good sealing effect when the rigid wheel 1 is assembled with the rigid bearing. No specific limitation is imposed herein.

[0039] For the rigid wheel 1, when it is formed by turning, the basic structure is generally turned out first, that is, the annular structure with a shoulder in which the first recessed portion 13 is provided. Then the end face used for assembly and the axial outer wall of the rigid wheel 1 are ground. Due to process limitations, during mass production, due to the wear of the grinding wheel fillet and other conditions, during the grinding process of the end face of the second wheel body 11 facing the second shaft portion 12B and the outer wall of the second shaft portion 12B, the angle between the two is not easy to be processed, resulting in a step. In the assembly of the harmonic reducer, the shoulder at this position is likely to be severely damaged, and the sealing performance of the assembly between the rigid wheel 1 and the rigid bearing is poor, and there may even be a problem of grease leakage in the first recessed portion 13, affecting the rigidity of the harmonic reducer.

[0040] In the present application, by providing a second recessed portion 121 on the outer wall of the second shaft portion 12B, and by providing the second recessed portion 121 in a position close to the first recessed portion 13, the second recessed portion 121 can avoid the problem of steps appearing on the rigid wheel 1 during turning. At the same time, the second recessed portion 121 provided at this position does not affect the matching accuracy between the rigid wheel 1 and the rigid bearing during assembly. When the rigid wheel 1 and the rigid bearing are matched, the matching surfaces 111 of the two can fit well together, and the grease in the first recessed portion 13 will not leak, thus achieving a good sealing effect. Moreover, in the harmonic reducer, the second shaft portion 12B is mainly involved in the meshing with the flexspline, and the flexspline sleeve is sleeved into the second shaft portion 12B, and the two mesh. The second recessed portion 121 arranged on the second shaft portion 12B near the first recessed portion 13 can minimize the impact on the strength of the rigid wheel 1, ensure that the rigid wheel 1 and the flexible wheel do not engage abnormally during use, ensure the stability of performance parameters such as the rigidity and noise of the harmonic reducer, and improve the service life of the harmonic reducer.

[0041] In an optional embodiment, a second recessed portion 121 is annularly disposed on the outer sidewall of the second shaft portion 12B along the axial direction, forming an annular groove structure recessed inward from the outer sidewall of the second shaft portion 12B. Optionally, the second recessed portion 121 may be configured as an arcuate surface recessed inward from the outer sidewall along the radial direction, or may be a multi-faceted structure having a bottom wall and sidewalls with a smooth transition between the bottom wall and the sidewalls, or may be other structures, which are not described in detail here. That is, the cross-sectional shape of the second recessed portion 121 may include various shapes, such as U-shaped, circular, elliptical, etc., as long as the inner surface of the second recessed portion 121 is free of sharp corners to avoid stress concentration, and no specific limitation is given here.

[0042] It can be understood that the rigid wheel 1 is a hollow annular structure, the interior of which is used to engage with the flexible wheel sleeve. The rigid wheel 1 has an axis, which is also the axis of the first wheel body 12 and the second wheel body 11. Its axial direction L is the direction indicated by the arrow L in the figure, and its radial direction W is the direction indicated by the arrow W in the figure. The axial direction L and the radial direction W are perpendicular to each other. For ease of description, the axial direction L and the radial direction W mentioned in this application correspond to the directions described above and will not be emphasized separately later.

[0043] The specific structure of the rigid wheel 1 provided in the embodiment of the present application is further described in detail below with reference to the accompanying drawings.

[0044] See also Figure 3 and Figure 4In the embodiment of the present application, the rigid wheel 1 is provided with a mating surface 111 on the side of the second wheel body 11 facing the second shaft portion 12B, and the first recessed portion 13 is located on the mating surface 111. That is, on the basis of processing the rigid wheel 1 into an annular structure with a shoulder, a first recessed portion 13 is provided on the mating surface 111, corresponding to the connection position between the first wheel body 12 and the second wheel body 11, and arranged along the circumference of the first wheel body 12. To facilitate the subsequent description of this application, along the axial direction L, with the bottom wall of the first recessed portion 13 extending inwardly within the second wheel body 11 as a reference, the first wheel body 12 is divided into a continuous first shaft portion 12A and a second shaft portion 12B. The first shaft portion 12A is connected to the second wheel body 11, and a portion of the outer wall of the second shaft portion 12B and the second wheel body 11 enclose the first recessed portion 13. The extension line of the mating surface 111 in the radial direction W is located on the second shaft portion 12B, and will not be emphasized separately in the following.

[0045] Optionally, the mating surface 111 is used to fit with the end face of the rigid bearing, so the mating surface 111 needs to be processed into a surface that can better fit with the end face of the rigid bearing. For example, if the end face of the rigid bearing is a plane, the mating surface 111 is processed into a plane that is parallel to the radial direction W. Alternatively, the mating surface 111 can also be set as other surfaces that can fit with the end face of the rigid bearing, such as a curved surface, an inclined surface, or a stepped surface, etc., which are not specifically limited here. Generally, in order to facilitate processing and ensure a good fitting effect, the mating surface 111 is set on a plane parallel to the radial direction W. For the convenience of describing this application, the following takes the mating surface 111 being set as a plane parallel to the radial direction W as an example, and will not be emphasized separately in the following.

[0046] In an alternative embodiment, the annular inner wall of the first wheel body 12 is provided with gear teeth 122 for meshing with the flexspline sleeve. Multiple gear teeth 122 are evenly distributed around the circumference of the annular inner wall. Alternatively, the meshing of the flexspline sleeve with the protruding second shaft portion 12B is primarily responsible for meshing with the flexspline sleeve. Therefore, the gear teeth 122 are at least located on the inner sidewall of the second shaft portion 12B.

[0047] It is understandable that gear teeth 122 may also be provided on the inner side wall of the first shaft portion 12A. The gear teeth 122 at this position may be the same as or different from the gear teeth 122 provided on the second shaft portion 12B in size and arrangement. When the gear teeth 122 are different from those of the second shaft portion 12B, they may be matched with different flexible splines to increase the universal performance of the rigid wheel 1. No specific limitation is made here.

[0048] In an alternative embodiment, along the radial direction W, an extension of the first straight line formed by the mating surface 111 and the second shaft portion 12B have an intersection 111a. The intersection 111a is located within the second recess 121, or the intersection 111a is located outside the second recess 121, and the second recess 121 is located on the side of the intersection 111a away from the first shaft portion 12A. The position range of the second recess 121 on the second shaft portion 12B is limited. That is, the second recess 121 is located at the position where the mating surface 111 and the outer wall of the second shaft portion 12B meet. The second recess 121 is provided within a certain range of this position so that the second recess 121 intersects with the first recess 13, or the first recess 13 and the second recess 121 do not intersect.

[0049] The setting position of the second recessed portion 121 is coordinated with the structure associated with the mating surface 111. On the one hand, the second recessed portion 121 can be used as a tool withdrawal groove during grinding, so that when grinding the mating surface 111 and the outer wall of the second shaft portion 12B, when the grinding wheel fillet is grinding two mutually perpendicular surfaces, the second recessed portion 121 at the intersection of the two can provide a clearance for the grinding wheel, avoiding the situation where the grinding wheel fillet is worn or steps appear when the processing is not in place, so that the mating surface 111 can better fit with the end face of the rigid bearing, thereby ensuring the accuracy of the assembly of the mating surface 111 or the outer wall of the second shaft portion 12B with the rigid bearing, and ensuring better sealing performance.

[0050] On the other hand, the second recess 121 provided at this location minimizes the impact on the strength of the rigid wheel 1, preventing the second shaft portion 12B from tearing under high torque when meshing with the flexspline sleeve. Furthermore, the second recess 121 improves the precision of the fit with the rigid bearing, resulting in higher precision and stability in the meshing between the rigid wheel 1 and the flexspline, preventing abnormal meshing and ensuring stable performance of the harmonic reducer during mass production, thereby increasing its service life.

[0051] Optionally, the second recessed portion 121 can be simultaneously turned out during the turning process, or can be processed separately in a subsequent process. As long as the second recessed portion 121 exists when the mating surface 111 and the outer wall of the rigid wheel 1 are ground, no specific limitation is made here.

[0052] In an optional embodiment, the intersection 111a is located within the second recess 121. Along the axial direction L, a first predetermined distance P1 is defined between the edge of the second recess 121 facing the first shaft portion 12A and the intersection 111a. The first recess 13 has a predetermined depth H1, where P1 ≤ 1 / 3 × H1. When the second recess 121 is positioned at the junction of the mating surface 111 and the outer wall of the second shaft portion 12B, if the second recess 121 is large or if it is necessary to ensure the high strength of the rigid wheel 1, the edge of the second recess 121 near the first shaft portion 12A can be extended along the axial direction L to the second shaft portion 12B that encloses the first recess 13. This ensures high strength during meshing of the rigid wheel 1 while not affecting the sealing performance of the sealing ring provided in the first recess 13.

[0053] In an optional embodiment, intersection 111a is located outside the second recessed portion 121. Along the axial direction L, the edge of the second recessed portion 121 facing the first shaft portion 12A intersects with intersection 111a, or the edge of the second recessed portion 121 facing the first shaft portion 12A is a second predetermined distance from intersection 111a. When the second recessed portion 121 is positioned at the junction of the mating surface 111 and the outer wall of the second shaft portion 12B, if high sealing performance is required, the edge of the second recessed portion 121 near the first shaft portion 12A along the axial direction L cannot extend into the second shaft portion 12B that encloses the first recessed portion 13. This edge can be located directly at intersection 111a or at a second predetermined distance from intersection 111a to ensure that the rigid wheel 1 maintains a certain strength while also providing high sealing performance. It is understood that the second predetermined distance can be adaptively adjusted based on actual conditions, for example, it can be between 0 mm and 5 mm, and is not specifically limited here.

[0054] Optionally, whether the intersection 111a described in the above embodiments is located inside or outside the second recessed portion 121, and the specific position and size of the first preset distance P1 and the second preset distance, etc., may be related to the size and shape of the first recessed portion 13, the strength of the second shaft portion 12B to be guaranteed, the size and shape of the second recessed portion 121, the thickness of the second shaft portion 12B, and the size and shape of the gear teeth 122, etc., and need to be comprehensively considered according to actual conditions. It may be affected by one or more of the above-mentioned situations, or may also be affected by other situations not listed, and no specific limitation is made here.

[0055] In an optional embodiment, the inner sidewall of the second shaft portion 12B is provided with a plurality of gear teeth 122 arranged continuously along the circumferential direction. Along the radial direction W, a first distance δ is defined between the tooth roots of the gear teeth 122 and the outer sidewall of the second shaft portion 12B. Along the radial direction W, the maximum depth of the second recess 121 within the second shaft portion 12B is a second distance Y3, where Y3 ≤ 1 / 4 × δ. This prevents the excessive depth of the second recess 121 from significantly affecting the strength of the rigid spline 1, thereby ensuring stable meshing between the gear teeth 122 of the second shaft portion 12B and the teeth of the flexspline sleeve.

[0056] Optionally, the depth of the second recess 121 may also be related to the position, size, and required strength of the second shaft portion 12B of the second recess 121 relative to the intersection 111a. When actually considering setting the depth of the second recess 121, it is sufficient to ensure that its maximum depth does not exceed one-fourth of the first distance δ. Its specific size may be determined based on the actual situation and the influence of one or more factors involved, and is not specifically limited here.

[0057] It can be understood that, in the above embodiments, although the position, shape, size, etc. of the second recessed portion 121 are further limited, when the second recessed portion 121 is actually processed, the second recessed portion 121 referred to is set at the position where the second shaft portion 12B is connected to the mating surface 111. It is necessary to consider one or more of the following conditions: the size and shape of the first recessed portion 13, the design of the gear teeth 122 of the second shaft portion 12B, the thickness of the second shaft portion 12B, the required strength of the second shaft portion 12B, etc., or it is necessary to additionally consider the influence of other environmental factors, mating components, etc., which are not specifically limited here.

[0058] This application also provides a specific embodiment, see Figure 3 and Figure 4 In the cross section passing through the axis of the first wheel body 12, the contour shape of the second recessed portion 121 can be obtained according to the contour trajectory equation to obtain the corresponding contour trajectory M, thereby obtaining the specific position, size, shape, etc. of the second recessed portion 121 on the second shaft portion 12B according to the contour trajectory M.

[0059] Specifically, they may include:

[0060] Establish a coordinate system with the origin O. A cross section of the rigid wheel 1 is made along the axial direction L through the axis of the first wheel body 12. In this cross section, the straight line formed by the outer wall of the second shaft portion 12B is translated outward by a third distance Y2 along the radial direction W. A mating surface 111 is provided on the side of the second wheel body 11 facing the first shaft portion 12A. The straight line formed by the mating surface 111 is translated along the axial direction L toward the second shaft portion 12B by a fourth distance Y1. The intersection of these two translated straight lines serves as the coordinate origin O.

[0061] Define the contour trajectory M equation with the coordinate origin O:

[0062] x=r(k×t-sint)

[0063] y = r(k-cost);

[0064] Wherein, x is the horizontal coordinate, y is the vertical coordinate, h×10 / D≤r≤h / δ, (h-δ) / (D / 2)≤k≤(h+δ) / (D / 2), -π≤t≤π, h is the full tooth height of the gear tooth 122, D is the pitch circle diameter of the gear tooth 122, δ is the thickness of the gear tooth 122 from the root to the outer wall of the second shaft portion 12B, t is the angular variable of the tooth shape of the gear tooth 122, k is the proportional coefficient, and r is the base circle radius.

[0065] It is understood that the selection of the coordinate origin O can be considered based on factors such as the required strength of engagement with the flexspline sleeve or the condition of the first recess 13. For example, the third distance Y2 and the fourth distance Y1 can both be set to 0, so that the coordinate origin O is located at the intersection of the mating surface 111 and the outer wall of the second shaft portion 12B, so that the second recess 121 partially intersects the first recess 13. Alternatively, at least one of the third distance Y2 and the fourth distance Y1 can be set to a value other than 0, and whether the contour trajectory obtained based on this coordinate intersects or does not intersect with the first recess 13 varies depending on the base circle radius r of the selected contour trajectory M, which is not specifically limited here. The value ranges of the third distance Y2 and the fourth distance Y1 at the coordinate origin O may include: 0 ≤ Y1 ≤ 0.25 × r, and 0 ≤ Y2 ≤ 0.5 × r.

[0066] Optionally, the value of the base circle radius r and the value of the proportional coefficient k can be adaptively selected according to actual conditions and are not specifically limited here. Preferably, 0.1mm≤r≤0.5mm, -0.01≤k≤0.05. For example, when the proportional coefficient k is 0, the base circle radius r is selected from a value within the above range, and the resulting trajectory is circular; when the proportional coefficient k is non-zero, the base circle radius r is selected from a value within the above range, and the resulting trajectory is non-circular. This allows the second recess to form different shapes depending on the value, which is not detailed here.

[0067] This application also provides a harmonic reducer, see Figure 5The harmonic reducer can be widely used in fields with high precision requirements such as industrial robots and aerospace. The harmonic reducer mainly consists of three basic components, namely a rigid wheel 1, a flexwheel 3 and a wave generator 4. The rigid wheel 1 is fixed by a rigid bearing 2. Bolts pass through the screw holes 14 of the rigid wheel 1 to connect the rigid wheel 1 and the rigid bearing 2 so that the mating surface 111 and the end face of the rigid bearing 2 are in contact. During the working process, the rigid wheel 1 is generally fixed. When the wave generator 4 rotates, it forces the flexwheel 3 to produce elastic deformation, so that the gear teeth of the flexwheel 3 and the gear teeth 122 of the rigid wheel 1 enter a meshing state, thereby realizing transmission. The rigid wheel 1 is the rigid wheel 1 described above, so that during use, the rigid wheel 1 can be more tightly matched with the rigid bearing 2, ensuring that the problem of sealing failure will not occur during the working process, while ensuring that the rigid wheel 1 and the flexwheel 3 maintain a good meshing effect and avoid abnormal meshing. For the specific structure of the rigid wheel 1, please refer to the above embodiments and will not be described in detail here.

[0068] It should be noted that the rigid wheel and harmonic reducer provided in the embodiments of the present application are not limited to use in industrial robots and aerospace fields, but can also be used in other scenarios that require setting transmission accuracy, large speed ratio, small size and simple structure, such as precision equipment manufacturing and other fields, which will not be repeated here.

[0069] It should be noted that references in this specification to "one embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," and the like indicate that the described embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not.

[0070] It should be readily understood that “on,” “above,” and “over” in this disclosure should be interpreted in the broadest manner, such that “on” means not only “directly on something,” but also includes “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above” or “over,” but also includes “above” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0071] Additionally, spatially relative terms, such as "below," "beneath," "beneath," "above," and the like, may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be in other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0072] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A rigid wheel for a harmonic reducer, characterized in that: The rigid wheel comprises: The first wheel body includes a first shaft portion and a second shaft portion continuously distributed along the axial direction of the first wheel body. a second wheel body, located on an outer circumference of the first shaft portion, the second wheel body having a first recessed portion formed on a side facing the second shaft portion and enclosed by an outer side wall of the second shaft portion, the outer side wall of the second shaft portion having a second recessed portion, the second recessed portion being disposed adjacent to the first recessed portion; The second recessed portion is annularly provided on the outer side wall of the second shaft portion along the axial direction. The second recessed portion is configured as an arcuate surface recessed inwardly along the radial direction from the outer side wall, and the axial direction intersects the radial direction; The inner side wall of the second shaft portion is provided with a plurality of gear teeth continuously arranged along the circumferential direction. In the cross section passing through the axis of the first wheel body, the contour shape of the second recessed portion is obtained according to the contour trajectory equation with the coordinate origin being O. The contour trajectory equation is: x=r(k×t-sint) y=r(k-cost); x is the abscissa, y is the ordinate, h×10 / D≤r≤h / δ, (h-δ) / (D / 2)≤k≤(h+δ) / (D / 2), -π≤t≤π, h is the full tooth depth of the gear tooth, D is the pitch circle diameter of the gear tooth, δ is the thickness of the gear tooth from the root to the outer side wall at the second shaft portion, t is the angular variable of the gear tooth profile, k is the proportional coefficient, and r is the base circle radius; Among them, the straight line formed by the outer side wall of the second shaft portion is translated outwardly a third distance Y2 along the radial direction, and the second wheel body is provided with a mating surface on the side facing the first shaft portion. The straight line formed by the mating surface is translated along the axial direction toward the second shaft portion by a fourth distance Y1, and the intersection of the two translated straight lines serves as the coordinate origin O, 0≤Y1≤0.25×r, 0≤Y2≤0.5×r.

2. The rigid wheel according to claim 1, characterized in that: Along the axial direction, the second recessed portion is annularly arranged on the outer side wall of the second shaft portion. The second recessed portion has a bottom wall and side walls, and the bottom wall and the side walls are smoothly connected.

3. The rigid wheel according to claim 1, characterized in that: A mating surface is provided on a side of the second wheel body facing the second shaft portion, and the first recessed portion is located on the mating surface. Along the radial direction, the extension line of the first straight line formed by the mating surface has an intersection with the second shaft portion, and the intersection is located inside the second recessed portion, or the intersection is located outside the second recessed portion, and the second recessed portion is located on the side of the intersection away from the first shaft portion.

4. The rigid wheel according to claim 3, characterized in that: The intersection is located in the second recessed portion, and a first preset distance P1 is located between the edge of the second recessed portion facing the first shaft portion and the intersection in the axial direction. The first recessed portion has a preset depth H1, where P1≤1 / 3×H1.

5. The rigid wheel according to claim 3, characterized in that: The intersection is located outside the second recessed portion, and along the axial direction, the edge of the second recessed portion facing the first shaft portion intersects with the intersection, or the edge of the second recessed portion facing the first shaft portion has a second preset distance from the intersection.

6. The rigid wheel according to claim 1, characterized in that: The inner side wall of the second shaft portion is provided with a plurality of gear teeth arranged continuously along the circumferential direction, and along the radial direction, there is a first distance δ between the tooth roots of the gear teeth and the outer side wall of the second shaft portion. Along the radial direction, the maximum depth of the second recessed portion at the second shaft portion is a second distance Y3, where Y3 ≤ 1 / 4×δ.

7. The rigid wheel according to claim 1, characterized in that: 0.1mm≤r≤0.5mm, -0.01≤k≤0.

05.

8. A harmonic reducer, characterized in that: It comprises a rigid wheel, wherein the rigid wheel is the rigid wheel as described in any one of claims 1-7.

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