A rigid wheel structure and a resonant speed reducer comprising the same

Abstract

The application provides a rigid wheel structure and a resonant speed reducer comprising the same, relates to the technical field of speed reducers, and solves the technical problem of the reduction in strength and the easy failure of a flexible wheel in a resonant speed reducer. The rigid wheel structure comprises a rigid wheel in meshing connection with a flat-toothed flexible wheel. The surface of the rigid wheel in contact with the flexible wheel comprises, in sequence along the axial direction, a front section, a middle section and a rear section. The front section is a variable displacement modification structure. The rear section is a variable displacement modification structure. The middle section is a flat-toothed section structure. The application is based on the flexible wheel deformation theory and designs a new rigid wheel structure with a space tooth profile. The flat-toothed flexible wheel is used. The space three-dimensional tooth profile parameters of the rigid wheel are designed to make the thickness of the flexible wheel tooth ring consistent, improve the strength of the flexible wheel, prolong the service life of the speed reducer, improve the load capacity of the speed reducer, make the meshing depth of the rigid and flexible wheel teeth consistent in the axial direction, improve the meshing performance and transmission precision, and make the flexible wheel tooth mesh in smoothly without interference under a large load.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of speed reducer, in particular to a rigid wheel structure and a harmonic reducer comprising the same. BACKGROUND

[0002] The harmonic reducer is a transmission device that uses a wave generator to make the flexspline produce controllable elastic deformation and engage with the rigid wheel to achieve transmission of motion and power. It has the advantages of large transmission ratio, simple structure, small size, light weight, strong carrying capacity, etc., and is widely used in industrial robots, aerospace and other fields.

[0003] The flexspline in the common harmonic reducer product on the market will produce an opening angle under the action of the wave generator, resulting in different meshing depths of the flexspline and the rigid wheel teeth at different axial positions, and even interference, causing the teeth to bend.

[0004] In order to avoid this situation, the common harmonic reducer usually performs displacement processing on the flexspline teeth, so that the addendum height of the flexspline teeth at different axial positions is different, ensuring the consistency of the axial meshing depth and avoiding interference. However, since the inner wall of the flexspline is usually a straight cylinder, the displacement processing of the flexspline teeth will cause the wall thickness of the flexspline ring to become thinner, which greatly reduces the strength of the flexspline which is already very thin, making it more prone to failure. SUMMARY

[0005] The purpose of the present application is to provide a rigid wheel structure and a harmonic reducer comprising the same, to solve the technical problems of displacement processing of the flexspline in the prior art, reduced strength and easy failure.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a rigid wheel structure comprising a rigid wheel connected with a flat-toothed flexspline, the surface of the rigid wheel in contact with the flexspline comprises a front section, a middle section and a rear section along the axial direction in sequence, and the front section is a variable displacement profile structure to ensure the consistency of the axial meshing depth with the flexspline.

[0008] In some embodiments, the variable displacement profile structure of the front section is a bevel structure protruding towards the middle section.

[0009] In some embodiments, the profile angle of the front section is a1=k1*arctan(ω0 / (l-x)); wherein k1 is the front section profile coefficient, the value range is 0.85-0.9, ω0 is the deformation amount of the wave generator long axis, x is the wave generator ball section installation depth, and l is the flexspline cylinder length.

[0010] In some embodiments, the rear section is a modified structure to ensure smooth engagement with the flexspline under heavy loads.

[0011] In some embodiments, the displacement and shaping structure of the rear section is an inclined structure that protrudes towards the intermediate section.

[0012] In some embodiments, the shaping angle of the rear section is a2=k2*arctan(ω0 / (lx)); where k2 is the shaping coefficient of the rear section, and the value range is 0.9-1.15; ω0 is the deformation of the long axis of the wave generator, x is the insertion depth of the ball section of the wave generator, and l is the length of the flexible wheel cylinder.

[0013] In some embodiments, the intermediate cross section is a straight tooth segment structure.

[0014] In some embodiments, the length of the intermediate section is l0 = k0 * d, where d is the width of the flexure gear ring.

[0015] Secondly, the present invention provides a resonant reducer, comprising a straight-tooth flexure and a rigid wheel structure that meshes with the flexure for transmission.

[0016] In some embodiments, the flexible wheel is cap-shaped or cup-shaped.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The rigid wheel of this invention is a novel rigid wheel with a spatial tooth profile designed based on the theory of flexible wheel deformation. It uses a straight tooth flexible wheel and designs the spatial three-dimensional tooth profile parameters of the rigid wheel to make the thickness of the flexible wheel tooth ring uniform, thereby improving the strength of the flexible wheel, extending the life of the reducer, and improving the load capacity of the reducer. At the same time, it makes the meshing depth of the rigid and flexible wheel teeth consistent in the axial direction, improving meshing performance and transmission accuracy. Under large loads, it ensures smooth meshing of the flexible wheel teeth without interference. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the meshing of the rigid wheel and the flexible wheel of the present invention;

[0021] Figure 2 This is a schematic diagram of the flex wheel structure in the harmonic reducer of the present invention;

[0022] Figure 3This is a schematic diagram of the structure of the harmonic reducer of the present invention.

[0023] In the figure, 6 is the rigid bearing; 7 is the flexible wheel; 8 is the rigid wheel; 9 is the wave generator; 31 is the front section; 32 is the middle section; 33 is the rear section; 34 is the cam; 35 is the inner ring of the flexible bearing; 36 is the ball; 37 is the outer ring of the flexible bearing; 38 is the flexible wheel tooth; 40 is the front section displacement modification; 41 is the spur tooth section; and 42 is the rear section displacement modification. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] like Figure 1 As shown, the present invention provides a rigid wheel structure, including a rigid wheel 8 that meshes with a straight toothed flexible wheel 7. The surface of the rigid wheel 8 that contacts the flexible wheel 7 includes a front section 31, a middle section 32 and a rear section 33 in sequence along the axial direction. The front section 31 is a modified structure to ensure that the axial meshing depth with the flexible wheel 7 is consistent.

[0026] To ensure that the meshing depth of the rigid-flexible gear teeth 38 remains consistent across all interfaces and to eliminate bending and interference of the flexible gear teeth, the front section 31 of the rigid gear teeth is subjected to displacement treatment.

[0027] It should be noted that the front section deformation modification 40 is a sloping structure that protrudes towards the middle section 32. In other words, the thickness of the front section deformation modification 40 on the side closer to the middle section 32 is greater than the thickness of the front section deformation modification 40 on the side farther from the middle section 32.

[0028] like Figure 1 and Figure 2 As shown, in this embodiment, the modification angle of the front section 31 is a1=k1*arctan(ω0 / (lx)); where k1 is the front section modification coefficient, with a value range of 0.85-0.9, ω0 is the deformation of the long axis of the wave generator, x is the insertion depth of the ball section of the wave generator, and l is the length of the flexible wheel cylinder.

[0029] To ensure smooth engagement of the flexible gear under heavy loads without interference, the rear section of the rigid gear teeth is repositioned, such as... Figure 1 As shown, the rear section 33 is a modified structure to ensure smooth engagement with the flexible wheel 7 under heavy loads.

[0030] Specifically, the rear section displacement modification 42 is a sloping structure that protrudes towards the middle section 32.

[0031] In other words, the rear section displacement modification 42 degree on the side closer to the middle section 32 is greater than the thickness of the rear section displacement modification 42 on the side farther from the middle section 32.

[0032] Furthermore, the modification angle of the rear section 33 is a2=k2*arctan(ω0 / (lx)); where k2 is the modification coefficient of the rear section, and the value range is 0.9-1.15; ω0 is the deformation of the long axis of the wave generator, x is the insertion depth of the ball section of the wave generator, and l is the length of the flexible wheel cylinder.

[0033] like Figure 1 As shown, the middle section 32 has a straight tooth segment 41 structure, and the flexible wheel 7 also has straight teeth.

[0034] Furthermore, such as Figure 1 and Figure 2 As shown, the length of the middle section 32 is l0=k0*d, where d is the width of the flexure gear ring.

[0035] The rigid wheel of this invention is a novel rigid wheel with a spatial tooth profile designed based on the theory of flexible wheel deformation. It uses a straight tooth flexible wheel and designs the spatial three-dimensional tooth profile parameters of the rigid wheel to make the thickness of the flexible wheel tooth ring uniform, thereby improving the strength of the flexible wheel, extending the life of the reducer, and improving the load capacity of the reducer. At the same time, it makes the meshing depth of the rigid and flexible wheel teeth consistent in the axial direction, improving meshing performance and transmission accuracy. Under large loads, it ensures smooth meshing of the flexible wheel teeth without interference.

[0036] like Figure 3 As shown, the present invention provides a resonant reducer, comprising a straight-toothed flexible gear 7 and a rigid wheel 8 that meshes with the flexible gear 7 for transmission.

[0037] In order to ensure the strength of the flexible gear ring, the 38 teeth of the flexible gear are straight and do not change in any cross section, and their root circles are the same.

[0038] The harmonic damper of the present invention also includes a rigid bearing 6 and a cam wave generator 9. The cam wave generator 9 is assembled from a cam 34 and a flexible bearing. The cam wave generator 9 is set in the inner hole of the flexible wheel and rotates to generate controllable elastic deformation. Motion and power transmission are realized through the meshing of the rigid wheel 8 and the flexible wheel 7. After the wave generator 9 is installed, the flexible wheel 7 undergoes elliptical deformation in a section perpendicular to the axial direction. Since the generatrix of the flexible wheel has only one fixed point and one contact point in the axial direction, the radial deformation of the flexible wheel changes linearly in the axial direction.

[0039] Specifically, the flexible bearing includes a flexible bearing inner ring 35, a flexible bearing outer ring 37, and balls 36.

[0040] If the opening direction of the flexible wheel 7 is specified as the front section 31, and the opposite direction as the rear section 33, and the intermediate section of the wave generator 9 is specified as the intermediate section 32, when the wave generator 9 is installed into the flexible wheel 7, the flexible wheel 7 will have an angle along its long axis. This angle is related to the length of the flexible wheel cylinder, the deformation of the long axis of the wave generator 9, and the installation depth of the wave generator 9. To avoid excessive interference and bending of the flexible wheel teeth, the front section of the rigid wheel is modified by displacement. To ensure its meshing accuracy and performance under medium load conditions, a section of straight teeth that does not change position is retained in the intermediate section, and this straight tooth section is symmetrical about the intermediate section of the wave generator. To ensure smooth meshing of the flexible wheel without interference under large loads, the rear section of the rigid wheel teeth is modified by displacement.

[0041] The angle of the front section displacement modification is a1=k1*arctan(ω0 / (lx));

[0042] The length of the straight tooth segment in the middle section is l0 = k0 * d;

[0043] The angle for modifying the rear section is a2 = k2 * arctan(ω0 / (lx));

[0044] in:

[0045] d is the width of the flexible gear ring.

[0046] ω0 is the deformation of the long axis of the wave generator, l is the length of the flexible wheel cylinder, x is the insertion depth of the ball cross-section of the wave generator; k0 is the length coefficient of the middle section, with a value range of 0.1~0.25;

[0047] k1 is the front section modification coefficient. In order to ensure transmission accuracy and zero backlash, a small amount of interference should be left. The value range of the modification coefficient is 0.85~0.9.

[0048] k2 is the rear section modification coefficient. To ensure smooth engagement of the flexible wheel without interference under large loads, a small clearance is selected. The modification coefficient ranges from 0.9 to 1.15.

[0049] The resonant reducer of this invention, based on the deformation theory of flexure wheels, designs a novel rigid wheel structure with a spatial tooth profile. The novel rigid wheel 8 and the coplanar straight-toothed flexure wheel 7 mesh with each other. By using the coplanar straight-toothed flexure wheel 7, the influence of the displacement of the flexure wheel teeth 38 on the thickness of the flexure wheel 7 is eliminated, thus improving the strength of the flexure wheel 7. By displacing the front section 31 of the rigid wheel 8 and designing spatial three-dimensional tooth profile parameters, the axial meshing depth is kept consistent while using the coplanar straight-toothed flexure wheel 7, reducing the bending deformation of the flexure wheel teeth 38. By displacing the rear section of the rigid wheel and designing spatial three-dimensional tooth profile parameters, the meshing of the flexure wheel engagement area is ensured smoothly and without interference under large loads while using the coplanar straight-toothed flexure wheel 7.

[0050] Among them, the flexible wheel 7 is shaped like a hat or a cup.

[0051] First, it should be noted that "inward" refers to the direction towards the center of the storage space, while "outward" refers to the direction away from the center of the storage space.

[0052] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the appendix. Figure 1 The orientations or positional relationships shown are for the purpose of facilitating and simplifying the description of the present invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rigid wheel structure, characterized in that, It includes a rigid wheel that meshes with a straight-toothed flexible wheel. The surface of the rigid wheel that contacts the flexible wheel includes a front section, a middle section, and a rear section in sequence along the axial direction. The front section is a modified structure to ensure that the axial meshing depth with the flexible wheel is consistent. The displacement and modification structure of the front section is an inclined structure that protrudes towards the middle section; The rear section is a displacement-modified structure; The displacement and shaping structure of the rear section is an inclined structure that protrudes towards the middle section.

2. The rigid wheel structure according to claim 1, characterized in that, The front section modification angle is a1=k1*arctan(ω0 / (lx)); where k1 is the front section modification coefficient, with a value range of 0.85-0.9, ω0 is the deformation of the long axis of the wave generator, x is the insertion depth of the ball section of the wave generator, and l is the length of the flexible wheel cylinder.

3. The rigid wheel structure according to claim 1, characterized in that, The modification angle of the rear section is a2=k2*arctan(ω0 / (lx)); where k2 is the modification coefficient of the rear section, and the value range is 0.9-1.15; ω0 is the deformation of the long axis of the wave generator, x is the insertion depth of the ball section of the wave generator, and l is the length of the flexible wheel cylinder.

4. The rigid wheel structure according to claim 1, characterized in that, The intermediate cross section has a straight tooth segment structure.

5. The rigid wheel structure according to claim 4, characterized in that, The length of the intermediate section is l0 = k0 * d, where d is the width of the flexure gear ring.

6. A resonant reducer, characterized in that, It includes a straight-toothed flexible gear and a rigid wheel structure as described in any one of claims 1-5 that meshes with the flexible gear to perform transmission.

7. The resonant reducer according to claim 6, characterized in that, The flexible wheel is either cap-shaped or cup-shaped.

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