Lightweight flexible gears and harmonic reducers

Abstract

This application provides a lightweight flexible wheel and a harmonic reducer, relating to the field of harmonic drive technology. The lightweight flexible wheel includes a cylinder and gear teeth. The circumferential surface of the cylinder includes a non-toothed region and a toothed region distributed along the axial direction, with gear teeth formed in the toothed region. A subtractive material section is formed in the non-toothed region, which includes a honeycomb topology structure. Through the design of the honeycomb topology structure, non-load-bearing redundant material in the non-toothed region is eliminated, reducing the overall mass of the flexible wheel and greatly increasing the heat dissipation surface area of ​​the flexible wheel, forming an effective heat dissipation channel. The heat generated by the harmonic reducer containing the lightweight flexible wheel during operation can be quickly dissipated into the surrounding environment or lubricating medium. The honeycomb topology structure has a continuous support network and can uniformly distribute stress when under load, maintaining structural integrity while reducing the weight of the flexible wheel and ensuring the overall stiffness of the flexible wheel. This solves the problem in the prior art of how to reduce the mass of the flexible wheel and improve its heat dissipation performance while ensuring its performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of harmonic transmission, in particular to a lightweight flexspline and a harmonic reducer. BACKGROUND

[0002] The harmonic reducer is widely used in the fields of robots, aerospace, precision instruments, etc. due to its advantages of large transmission ratio, high precision, strong bearing capacity, compact structure, etc. The flexspline as a key elastic element of the harmonic reducer produces controllable elastic deformation under the action of the wave generator, thereby transmitting motion and torque.

[0003] In the related art, in order to ensure that the flexspline can produce elastic deformation, the flexspline is usually designed as a thin-walled cup-shaped structure, and at the same time, in order to meet the requirements of high strength and high fatigue life of the flexspline, the wall thickness cannot be too thin, which limits the lightweight of the flexspline. The lightweight of the harmonic reducer is of great significance to improve the dynamic response of the robot, reduce inertia, and reduce energy consumption. In addition, during high-speed operation of the flexspline, heat is generated due to periodic elastic deformation, which can affect the performance of the lubricating grease, aggravate wear and even lead to failure if the heat dissipation is poor. SUMMARY

[0004] Therefore, the present application provides a lightweight flexspline and a harmonic reducer to solve the problem of how to reduce the mass of the flexspline while ensuring the performance of the flexspline and improving the heat dissipation performance of the flexspline in the prior art.

[0005] In order to achieve the above purpose, the present application provides the following technical solutions:

[0006] A lightweight flexspline, comprising a cylinder body and a gear tooth;

[0007] The peripheral surface of the cylinder body comprises a non-tooth area and a tooth area distributed in the axial direction, and the gear tooth is formed in the tooth area.

[0008] A subtractive part is formed in the non-tooth area, and the subtractive part comprises a honeycomb topology structure.

[0009] Optionally, the honeycomb topology structure comprises a plurality of hollow cells arranged in the circumferential and axial directions of the cylinder body, and a cell rib formed between adjacent two hollow cells.

[0010] Optionally, the hollow cell and the cell rib are provided with one layer; or

[0011] The hollow cell and the cell rib are provided with multiple layers, and the hollow cells of adjacent two layers are distributed in a staggered manner.

[0012] Optionally, the hollowed cell is a regular hexagon with a side length of a, the width of the cell rib is m, and in the non-tooth area, the thickness of the thinnest part of the cylinder wall is t, wherein:

[0013] a = x × t, 1 ≤ x ≤ 3;

[0014] m = y × t, 0.5 ≤ y ≤ 5.

[0015] Optionally, the hollowed cell is a regular hexagon with a side length of a, the width of the cell rib is m, and the relative density of the honeycomb topology is , , a and m satisfy: .

[0016] Optionally, the width of each cell rib is the same; or,

[0017] All the cell ribs have a plurality of widths, and the honeycomb topology is a symmetrical structure.

[0018] Optionally, it further comprises a connecting flange connected to the end of the cylinder, and the connecting flange is close to the non-tooth area.

[0019] In the axial direction of the cylinder, the length of the cylinder is T, and the distance between the transition angle of the honeycomb topology and the connecting flange is t1, t1 ≥ T × 5%.

[0020] Optionally, in the axial direction of the cylinder, the length of the cylinder is T, and the length of the honeycomb topology is t2, t2 ≤ T × 40%.

[0021] Optionally, the cell rib is a shape memory alloy material; and / or,

[0022] The honeycomb topology is integrally formed with the cylinder by additive manufacturing.

[0023] A harmonic reducer, comprising a flexspline, a harmonic reducer and a rigid wheel, the flexspline is the lightweight flexspline in any of the above.

[0024] The lightweight flexible wheel provided in this application includes a cylinder and gear teeth. The circumferential surface of the cylinder includes a non-toothed region and a toothed region distributed along the axial direction, and the gear teeth are formed in the toothed region. A subtractive material section is formed in the non-toothed region, and the subtractive material section includes a honeycomb topology. This design results in a localized material gap on the circumferential surface of the flexible wheel, presenting a honeycomb topology, thereby forming a subtractive material section in the non-toothed region of the flexible wheel. In this way, the honeycomb topology design eliminates non-load-bearing redundant material in the non-toothed region, reducing the overall mass of the flexible wheel. Furthermore, the honeycomb topology greatly increases the heat dissipation surface area of ​​the flexible wheel, forming an effective heat dissipation channel. The heat generated by the harmonic reducer where the lightweight flexible wheel is located during operation can be rapidly dissipated into the surrounding environment or lubricating medium through the forced convection path formed on the lightweight flexible wheel by the honeycomb topology, reducing the operating temperature rise and achieving both a reduction in the mass of the flexible wheel and an improvement in its heat dissipation performance. Furthermore, the cellular topology has a continuous support network, which allows it to uniformly distribute stress under load. This means that the stress generated by the elastic deformation (such as radial bending and axial compression) of the lightweight flexible wheel under the action of the wave generator can be evenly distributed. By avoiding local stress concentration, fatigue life is improved. The structural integrity is maintained while reducing the weight of the flexible wheel. While minimizing mass, it provides extremely high out-of-plane stiffness and buckling resistance, ensuring the overall stiffness of the lightweight flexible wheel. This helps maintain transmission accuracy and ensures the overall performance of the lightweight flexible wheel. It solves the problem in the prior art of how to reduce the mass of the flexible wheel and improve its heat dissipation performance while ensuring its performance. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 An isometric view of a lightweight flexible wheel provided in an embodiment of this application.

[0027] Figure 2 A side view of a lightweight flexible wheel provided in an embodiment of this application.

[0028] Figure 3 This is a schematic diagram of a cellular topology provided in an embodiment of this application.

[0029] Figure 4 A partial cross-sectional view of a lightweight flexible wheel provided in an embodiment of this application.

[0030] Figure 5 for Figure 4 Detailed view of point A in the middle.

[0031] Figure 6 The dimensions of the hollow cells and cell ribs provided in the embodiments of this application are shown in the diagram.

[0032] exist Figures 1-6 middle:

[0033] 11. Cylinder body; 12. Gear teeth; 13. Connecting flange;

[0034] 110. Cellular topology; 111. Hollow cell; 112. Cellular ribs;

[0035] 131. Transition angle. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] Harmonic reducers mainly consist of a rigid wheel, a flexible wheel, and a wave generator. They are gear transmission structures that transmit motion and power by having the flexible wheel undergo controllable elastic deformation through the wave generator and mesh with the rigid wheel. Existing flexible wheels are typically smooth, thin-walled, cup-shaped structures. In production practice, the applicant has found that lightweight improvements to flexible wheels mostly focus on using materials with higher specific strength or optimizing tooth profile design, with few fundamental innovative designs for the cylindrical structure. Therefore, there is an urgent need for a flexible wheel design that can achieve significant weight reduction and improved heat dissipation performance while ensuring sufficient fatigue strength and transmission accuracy.

[0038] like Figures 1-6 As shown, this application embodiment provides a lightweight flexible wheel, including a cylinder 11 and gear teeth 12. The peripheral surface of the cylinder 11 includes a non-toothed region and a toothed region distributed along the axial direction, and the gear teeth 12 are formed in the toothed region. A subtractive material portion is formed in the non-toothed region, and the subtractive material portion includes a honeycomb topology structure 110. The inner wall of the cylinder 11 opposite to the toothed region is used to cooperate with a wave generator, and the gear teeth 12 of the lightweight flexible wheel are used to mesh with the gear teeth of a rigid wheel.

[0039] This design features a partial material gap on the peripheral surface of the flexspline, forming a honeycomb topology 110, thus creating a subtractive section in the non-tooth region of the flexspline. This honeycomb topology 110 design eliminates non-load-bearing redundant material in the non-tooth region, reducing the overall mass of the flexspline. Furthermore, the honeycomb topology 110 significantly increases the heat dissipation surface area of ​​the flexspline, creating an effective heat dissipation channel. The heat generated by the harmonic reducer containing the lightweight flexspline during operation can be rapidly dissipated into the surrounding environment or lubricating medium through the forced convection path formed on the lightweight flexspline by the honeycomb topology 110, reducing the operating temperature rise and achieving both a reduction in the mass of the flexspline and improved heat dissipation. Yes; furthermore, the cellular topology 110 has a continuous support network, thus it can uniformly distribute stress when subjected to force. This means that the stress generated by the elastic deformation (such as radial bending and axial compression) of the lightweight flexible wheel under the action of the wave generator can be uniformly distributed. By avoiding local stress concentration, fatigue life is improved. While reducing the weight of the flexible wheel, structural integrity is maintained. While minimizing mass, it provides extremely high out-of-plane stiffness and buckling resistance, ensuring the overall stiffness of the lightweight flexible wheel. This helps maintain transmission accuracy and achieves overall performance assurance for the lightweight flexible wheel, solving the problem in existing technologies of how to reduce the mass of the flexible wheel and improve its heat dissipation while ensuring its performance. Moreover, the lightweight flexible wheel reduces its rotational inertia through its porous structure, thereby improving the dynamic response speed and acceleration of the harmonic drive system. It is suitable for high-dynamic scenarios such as robot joints and aerospace precision transmission systems, effectively improving transmission efficiency, dynamic response speed, and service life.

[0040] In some alternative embodiments, the cellular topology 110 includes a plurality of hollow cells 111 arranged in an array along the circumference and axial direction of the cylindrical body 11, and cell ribs 112 formed between adjacent hollow cells 111. Alternatively, the hollow cells 111 can be arranged periodically. The hollow cells 111 may be optionally designed to be regular hexagonal.

[0041] This configuration creates a continuous support network of ribs, which greatly reduces the material usage of the lightweight flexible wheel, achieving the maximum achievable lightweight design while ensuring the performance of the lightweight flexible wheel.

[0042] Of course, in some possible embodiments, it is also feasible to design the cellular topology 110 to include a plurality of block cells arranged in a circumferential and axial array along the cylinder 11, and grooves formed between two adjacent block cells, with only one layer of block cells and grooves.

[0043] In some preferred embodiments, the hollow cells 111 are distributed circumferentially along the cylinder 11.

[0044] Based on the honeycomb topology 110, which combines hollow cells 111 and cell ribs 112, in some optional embodiments, the hollow cells 111 and cell ribs 112 are provided in one layer; or, the hollow cells 111 and cell ribs 112 are provided in multiple layers, with the hollow cells 111 in adjacent layers being staggered. The multiple layers of hollow cells 111 in the honeycomb topology 110 are distributed along the radial direction of the cylinder 11. For each layer, the hollow cells 111 are staggered in the axial and circumferential directions, forming a honeycomb-like close-packed structure. This honeycomb topology 110 has higher porosity and lower mass density than other forms of matrix materials, and therefore has high specific stiffness, specific strength, and specific energy absorption. For example, the honeycomb topology 110 uses 15 layers of hollow cells 111 and cell ribs 112.

[0045] Considering that the thickness of the lightweight flexible wheel's cylinder 11 is not a constant, the thickness of the honeycomb topology 110 varies at different locations. Based on this, as... Figure 6 As shown, in some optional embodiments, the hollow cell 111 is a regular hexagon with a side length of a, the width of the cell rib 112 is m, and the width of the cell rib 112 is also the distance between two adjacent hollow cells 111. In the non-toothed area, the thickness of the thinnest part of the cylinder 11 wall is t, where: a=x×t, 1≤x≤3; m=y×t, 0.5≤y≤5.

[0046] Through testing and verification, it was found that when the dimensions of the hollow cell 111 and cell ribs 112 are related to the wall thickness at the thinnest point of the cylinder 11 within the aforementioned range, maximum material reduction can be achieved while ensuring the structural strength of the lightweight flexible wheel and without compromising its functionality. For example, x is 1.5 and y is 0.5.

[0047] In some optional embodiments, the hollow cell 111 is a regular hexagon with a side length of a, the width of the cell rib 112 is m, and the width of the cell rib 112 is also the distance between two adjacent hollow cells 111. The relative density of the honeycomb topology 110 is... , a and m satisfy: .

[0048] With this setup, the porosity of the cylinder 11 and the relative density of the honeycomb topology 110 are negatively correlated. In this way, by adjusting the design values ​​of the width m of the cell ribs 112 and the side length a of the hollow cell 111, the porosity can be quickly obtained, so as to achieve efficient adjustment of the expected material reduction effect.

[0049] In some alternative embodiments, the width of each cell reinforcement strip 112 is the same.

[0050] In some optional embodiments, all cell ribs 112 have multiple widths, and the honeycomb topology 110 is a symmetrical structure. That is, when the cell ribs 112 are not all of equal width, they are symmetrically distributed. The symmetry of the honeycomb topology 110 varies depending on the application scenario of the lightweight flexible wheel. For example, the cross-section of the cylinder 11 (the plane perpendicular to the axis) is used as the plane of symmetry, or the longitudinal section of the cylinder 11 (the plane coinciding with the axis) is used as the plane of symmetry.

[0051] In this way, in the actual design and production of lightweight flexible gears, selective design can be carried out according to the application scenario of the harmonic reducer where the lightweight flexible gear is located, making it more feasible.

[0052] It should be noted that the lightweight flexible wheel provided in this application may be, but is not limited to, a cup-shaped flexible wheel or a cap-shaped flexible wheel.

[0053] like Figures 4-5 As shown, in some optional embodiments, the lightweight flexible wheel also includes a connecting flange 13 that transitions to the end of the cylinder 11. The connecting flange 13 is located near the non-toothed area, meaning the lightweight flexible wheel is a cap-shaped flexible wheel. The connecting flange 13 can also be referred to as a flange or cap edge. In the axial direction of the cylinder 11, the length of the cylinder 11 is T, and the distance between the honeycomb topology 110 and the transition angle 131 of the connecting flange 13 is t1, where t1 ≥ T × 5%. The transition angle 131 of the connecting flange 13 can also be referred to as an arc-shaped transition surface. In this way, the honeycomb topology 110 is located away from the gear teeth 12 and close to the connecting flange 13.

[0054] Furthermore, in some optional embodiments, the length of the cylinder 11 in the axial direction is T, and the length of the honeycomb topology 110 is t2, where t2 ≤ T × 40%.

[0055] Through testing and verification, this configuration has shown that arranging the cellular topology 110 according to the above design parameter range ensures that the cylinder 11 can resist axial bending deformation in the thin-walled region, thus ensuring the structure's resistance to instability. For example, t1 is 0.06T and t2 is 0.2T.

[0056] In some optional embodiments, the cell ribs 112 are made of shape memory alloy material. This facilitates the adaptation of the honeycomb topology 110 to the elastic deformation process of the lightweight flexible wheel as a whole, enhances the fatigue resistance of the lightweight flexible wheel during elastic deformation, and improves the fatigue life of the lightweight flexible wheel.

[0057] In some optional embodiments, the honeycomb topology 110 is integrally formed with the cylinder 11 by additive manufacturing, which can be 4D printing. This configuration, through the stacking of cell ribs 112, constructs hollow cells 111, facilitating the processing and manufacturing of the honeycomb topology 110 and avoiding the difficulties of traditional processing methods.

[0058] Of course, when the hollow cell 111 of the cellular topology 110 is designed as a single layer, it is also feasible to manufacture the hollow cell 111 using the traditional milling process.

[0059] Based on the aforementioned lightweight flexible wheel, this application embodiment also provides a harmonic reducer, which includes a wave generator, a rigid wheel, and a flexible wheel. The flexible wheel is the aforementioned lightweight flexible wheel. The wave generator is fitted inside the lightweight flexible wheel, and the lightweight flexible wheel is fitted inside the rigid wheel and meshes with the rigid wheel's teeth. Since this harmonic reducer has the aforementioned lightweight flexible wheel, the beneficial effects brought by the lightweight flexible wheel are described above and will not be repeated here.

[0060] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0061] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0062] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0063] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0064] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0065] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A lightweight flexible gearwheel, characterized by, The gear includes a cylinder (11) and a gear tooth (12); The peripheral surface of the cylinder (11) includes a non-tooth area and a tooth area distributed in the axial direction, and the gear tooth (12) is formed in the tooth area; A subtractive part is formed in the non-tooth area, and the subtractive part includes a honeycomb topology structure (110); The honeycomb topology structure (110) includes a plurality of hollow cells (111) arranged in the circumferential and axial directions of the cylinder (11), and a cell rib (112) formed between two adjacent hollow cells (111), the hollow cells (111) and the cell ribs (112) are provided with multiple layers and are distributed in the radial direction of the cylinder (11), and the hollow cells (111) of two adjacent layers are distributed in a staggered manner.

2. The lightweight flexible gear wheel according to claim 1, wherein The hollow cell (111) is a regular hexagon with a side length of a, the width of the cell rib (112) is m, and in the non-tooth area, the thickness of the thinnest part of the cylinder (11) is t, wherein: a=x×t, 1≤x≤3; m=y×t, 0.5≤y≤5.

3. The lightweight flexible gear wheel according to claim 1, wherein The hollowed-out cell (111) is a regular hexagon with a side length of a, the width of the cell rib (112) is m, and the relative density of the honeycomb topology (110) is , , a and m satisfy: .

4. The lightweight flexible gear wheel according to claim 1, wherein The width of each cell rib (112) is the same; or, All the cell ribs (112) have multiple widths, and the honeycomb topology structure (110) is a symmetrical structure.

5. The lightweight flexible gear wheel according to claim 1, wherein It also includes a connecting flange (13) connected to the end of the cylinder (11), and the connecting flange (13) is close to the non-tooth area; In the axial direction of the cylinder (11), the length of the cylinder (11) is T, the distance between the transition angle (131) of the honeycomb topology structure (110) and the connecting flange (13) is t1, and t1≥T×5%.

6. The light-weight flexible gear wheel according to claim 1 or 5, characterized in that In the axial direction of the cylinder (11), the length of the cylinder (11) is T, and the length of the honeycomb topology structure (110) is t2, t2≤T×40%.

7. The lightweight flexible gear wheel according to claim 1, wherein The cell rib (112) is a shape memory alloy material; and / or, The honeycomb topology structure (110) is integrally formed with the cylinder (11) by additive manufacturing.

8. A harmonic reducer characterized by, The gear includes a cylinder (11) and a gear tooth (12); The peripheral surface of the cylinder (11) includes a non-tooth area and a tooth area distributed in the axial direction, and the gear tooth (12) is formed in the tooth area; A subtractive part is formed in the non-tooth area, and the subtractive part includes a honeycomb topology structure (110); The honeycomb topology structure (110) includes a plurality of hollow cells (111) arranged in the circumferential and axial directions of the cylinder (11), and a cell rib (112) formed between two adjacent hollow cells (111), the hollow cells (111) and the cell ribs (112) are provided with multiple layers and are distributed in the radial direction of the cylinder (11), and the hollow cells (111) of two adjacent layers are distributed in a staggered manner. The hollow cell (111) is a regular hexagon with a side length of a, the width of the cell rib (112) is m, and in the non-tooth area, the thickness of the thinnest part of the cylinder (11) is t, wherein: a=x×t, 1≤x≤3; m=y×t, 0.5≤y≤5. The width of each cell rib (112) is the same; or, All the cell ribs (112) have multiple widths, and the honeycomb topology structure (110) is a symmetrical structure. It also includes a connecting flange (13) connected to the end of the cylinder (11), and the connecting flange (13) is close to the non-tooth area; In the axial direction of the cylinder (11), the length of the cylinder (11) is T, the distance between the transition angle (131) of the honeycomb topology structure (110) and the connecting flange (13) is t1, and t1≥T×5%. In the axial direction of the cylinder (11), the length of the cylinder (11) is T, and the length of the honeycomb topology structure (110) is t2, t2≤T×40%. The cell rib (112) is a shape memory alloy material; and / or, The honeycomb topology structure (110) is integrally formed with the cylinder (11) by additive manufacturing. The gear includes a cylinder (11) and a gear tooth (12); The peripheral surface of the cylinder (11) includes a non-tooth area and a tooth area distributed in the axial direction, and the gear tooth (12) is formed in the tooth area; A subtractive part is formed in the non-tooth area, and the subtractive part includes a honeycomb topology structure (110); The honeycomb topology structure (110) includes a plurality of hollow cells (111) arranged in the circumferential and axial directions of the cylinder (11), and a cell rib (112) formed between two adjacent hollow cells (111), the hollow cells (111) and the cell ribs (112) are provided with multiple layers and are distributed in the radial direction of the cylinder (11), and the hollow cells (111) of two adjacent layers are distributed in a staggered manner.

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