A toothless harmonic reducer and driver

Abstract

The present invention provides a toothless harmonic reducer, comprising a wave generator assembly, a fixed wheel, a flexible wheel and a friction ring, wherein the friction ring is arranged on the flexible wheel; the wave generator assembly is arranged inside the flexible wheel, and the wave generator assembly actuates the flexible wheel and the friction ring to synchronously deform into an ellipse; the friction ring contacts the fixed wheel at the two short axis ends of the ellipse, and the friction ring does not contact the fixed wheel at the two long axis ends of the ellipse. The present invention also provides a driver. The harmonic reducer and driver provided by the present invention perform toothless harmonic reduction through the friction drive principle, which greatly improves the transmission efficiency; the flexible wheel and the friction ring are separately arranged, and the transmission efficiency and output torque of the harmonic reducer can be conveniently adjusted by changing the elasticity and hardness of the materials of the flexible wheel and the friction ring; the wave generator assembly, the fixed wheel and the friction ring can be expanded into multiple sets of parallel structures to improve the output torque.

Description

Technical Field

[0001] The present invention relates to the field of robotics technology, and in particular to a toothless harmonic reducer and a driver. Background Art

[0002] At present, most of the key joints of robots use harmonic reducers. Compared with other reducers, under the same speed ratio and the same load, the harmonic reducer has smooth transmission, the highest precision, the small structure volume, and the light weight. It is widely used in precision industries such as robots, CNC machine tools, and semiconductor equipment.

[0003] A harmonic reducer generally includes components such as a rigid wheel, a flexspline and a wave generator including a flexible bearing. Internal teeth are arranged on the steel wheel and external teeth are arranged on the flexspline. After the flexspline is actuated and deformed, the external teeth mesh with the internal teeth at two points. Toothed harmonic transmission is performed through the periodic harmonic deformation of the flexspline and the meshing of the teeth between the flexspline and the stator. The transmission efficiency is very low and the manufacturing cost is high. Summary of the invention

[0004] In order to solve at least one of the above technical problems, the purpose of the present invention is to provide a new type of toothless harmonic reducer and driver. The toothless harmonic reducer and driver provided by the present invention realize the harmonic deformation of the flexible wheel through the friction principle, and the transmission is stable and reliable, and the transmission efficiency is higher. At the same time, the harmonic reducer and driver can perform multi-stage friction drive expansion to increase the output torque.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a toothless harmonic reducer is provided, comprising a wave generator assembly, a stator, a flexible spline and a friction ring, wherein the friction ring is arranged on the flexible spline; the wave generator assembly is arranged in the flexible spline, and the wave generator assembly actuates the flexible spline and the friction ring to synchronously deform into an elliptical shape; at the two short axis end points of the elliptical friction ring, the friction ring contacts the stator, and at the two long axis end points of the elliptical friction ring, the friction ring does not contact the stator.

[0006] Furthermore, the flexible wheel includes a base body, the base body is a thin-walled cylinder, the inner circumferential surface of the base body is a smooth surface, the wave generator assembly abuts against the inner circumferential surface; the friction ring is arranged on the outer circumferential surface of the base body.

[0007] Furthermore, the base is provided with splines; the friction ring is provided with spline grooves; the friction ring and the base are connected by the splines and the spline grooves.

[0008] Furthermore, it also includes an output component, which includes an output disc and an output shaft; the output disc is provided with a large circular spline hole, and the output shaft is provided with a circular spline block, and the circular spline block can be inserted into the large circular spline hole in a shape-matched manner.

[0009] Furthermore, a connecting column is arranged on one end face of the base; a column hole is arranged on the output disk; the connecting column is inserted into the column hole, and the connecting column can only move relative to the output disk along the radial direction of the output disk under the restriction of the column hole.

[0010] Furthermore, the material elasticity of the flexible spline is greater than the material elasticity of the friction ring.

[0011] Furthermore, it also includes a shell assembly, which includes a bottom shell, a middle shell and a shell cover; the middle shell is arranged between the bottom shell and the shell cover; the bottom shell, the middle shell and the shell cover are connected in sequence by connecting screws; the fixed wheel is provided with a screw avoidance hole, and the connecting screw passes through the screw avoidance hole.

[0012] Furthermore, the fixed wheel is ring-shaped, and includes a positioning portion and a first friction portion. The fixed wheel is arranged on both sides of the middle shell through the positioning portion, and a friction cavity is formed between the first friction portions on both sides; the friction ring is arranged in the friction cavity; the friction ring includes a symmetrically arranged second friction portion; the contact between the friction ring and the fixed wheel is the contact between the first friction portion and the second friction portion.

[0013] The present invention also provides a toothless harmonic reducer, comprising a wave generator assembly, a fixed wheel assembly, a flexible wheel and a friction ring, wherein two or more of the friction rings are arranged on the flexible wheel at intervals; two or more of the wave generator assemblies are arranged in the flexible wheel, and the wave generator assembly actuates the flexible wheel and the friction ring to synchronously deform into an elliptical shape; at the two short axis end points of the elliptical friction ring, the friction ring is in contact with the fixed wheel assembly, and at the two long axis end points of the elliptical friction ring, the friction ring is not in contact with the fixed wheel assembly; the number of the wave generator assemblies, the fixed wheel assemblies and the friction rings is the same.

[0014] The present invention also provides a driver, comprising a motor and the above-mentioned harmonic reducer, wherein the harmonic reducer is installed at the output end of the motor.

[0015] Compared with the prior art, the harmonic reducer and driver provided by the present invention have the following beneficial effects:

[0016] The present invention performs toothless harmonic reduction by means of the friction drive principle, thus overcoming the shortcoming of low transmission efficiency caused by deformation of the flexspline teeth in traditional toothed harmonic reduction, and greatly improving the transmission efficiency of the harmonic reducer.

[0017] In the present invention, the flexible wheel and the friction ring are separately arranged, and the transmission efficiency and output torque of the harmonic reducer can be conveniently adjusted by changing the elasticity and hardness of the flexible wheel and the friction ring materials. The friction ring is made of a highly wear-resistant material with relatively high hardness, which can improve the output torque of the harmonic reducer. The flexible wheel is made of a highly wear-resistant material with relatively high elasticity, which is easy to produce harmonic deformation; the high wear resistance of the flexible wheel can reduce the influence caused by roller friction and improve the service life of the harmonic reducer.

[0018] In the present invention, the output disc and the output shaft are connected by a spline, so that backlash-free transmission can be realized without other connecting parts, and installation is convenient, which greatly simplifies the structure of the harmonic reducer.

[0019] In the present invention, the bottom shell, the middle shell and the shell cover are connected and installed through screws, which has a simple structure, is easy to install and reduces costs. The screw avoidance hole on the fixed wheel cooperates with the screw to effectively limit the position and prevent the fixed wheel from rotating.

[0020] The wave generator assembly, the stator and the friction ring in the present invention can be arranged into two or more groups according to actual working conditions, so as to facilitate expansion and improve the transmission efficiency and output torque of the harmonic reducer.

[0021] In summary, the present invention proposes a toothless harmonic reducer and driver with stable and reliable transmission, high efficiency and precision, and low cost, which has broad application prospects in the field of robotics. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of a driver with a harmonic reducer provided in the first embodiment of the present invention;

[0023] Figure 2 1 is an exploded schematic diagram of a driver with a harmonic reducer provided in Embodiment 1 of the present invention;

[0024] Figure 3 is a schematic diagram of the internal structure of the driver provided in the first embodiment of the present invention;

[0025] Figure 4 is a schematic structural diagram of a fixed wheel provided in Embodiment 1 of the present invention;

[0026] Figure 5 is a schematic diagram of the internal structure of the fixed wheel provided in the first embodiment of the present invention;

[0027] Figure 6 is a schematic diagram of the internal structure of the flexible pulley provided in the first embodiment of the present invention;

[0028] Figure 7 is a schematic structural diagram of a flexible pulley provided in Embodiment 1 of the present invention;

[0029] Figure 8is a schematic diagram of the structure of the output disk provided in the first embodiment of the present invention;

[0030] Fig. 9 is a schematic diagram of the structure of the output shaft provided in the first embodiment of the present invention;

[0031] Fig.10 is a schematic diagram of the overall structure of a driver with a harmonic reducer provided in Embodiment 2 of the present invention;

[0032] Fig.11 is an exploded schematic diagram of a driver with a harmonic reducer provided in Embodiment 2 of the present invention;

[0033] Fig.12 It is a schematic diagram of the internal structure of the driver provided in the second embodiment of the present invention.

[0034] The reference numerals are described as follows:

[0035] 1 motor, 2 bottom shell, 3 middle shell, 3-1 connecting ring, 4 shell cover, 5 wave generator assembly, 5-1 support frame, 5-2 roller, 6 fixed wheel, 6-1 positioning part, 6-2 first friction part, 7 friction ring, 7-1 spline groove, 7-2 second friction part, 8 flexible wheel, 8-1 base, 8-2 connecting column, 8-3 spline, 9 output disk, 9-1 column hole, 9-2 large circular spline hole, 10 output shaft, 10-1 circular spline block, 10-2 shaft rod. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. Please note that the embodiments described below are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the art or the product instructions shall be followed.

[0037] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] The harmonic reducer and the driver of the present invention will be described in detail below through specific embodiments:

[0040] Embodiment 1

[0041] like Figure 1-9 As shown, the driver described in this embodiment includes a motor 1 and a harmonic reducer.

[0042] The harmonic reducer provided in this embodiment includes: a housing assembly, a wave generator assembly 5, a stator 6, a friction ring 7, a flexible wheel 8 and an output assembly and other components.

[0043] The housing assembly includes a bottom housing 2, a middle housing 3 and a housing cover 4. The bottom housing 2 is provided with positioning holes adapted to the motor 1 for easy assembly; the bottom housing 2 is mounted on the output end face of the motor 1 by screws. The middle housing 2 is arranged between the bottom housing 2 and the housing cover 4; the bottom housing 2, the middle housing 3 and the housing cover 4 are connected as a whole by connecting screws in sequence, and a mounting cavity is formed inside the three, which provides mounting space for the internal components of the harmonic reducer.

[0044] The wave generator assembly 5, the fixed wheel 6, the friction ring 7, the flexible wheel 8 and the output assembly and other components are arranged in the installation cavity. The wave generator assembly 5 includes a support frame 5-1 and a roller 5-2; the central part of the support frame 5-1 is provided with a motor shaft hole, and the support frame 5-1 is connected to the motor output shaft through the motor shaft hole.

[0045] The fixed wheel 6 is annular as a whole, and includes a positioning portion 6-1 and a first friction portion 6-2. Preferably, the positioning portion 6-1 is a positioning boss, and the first friction portion 6-2 is a first friction slope. The fixed wheel 6 is also provided with a screw avoidance hole for the connection screw in the housing assembly to pass through. The connection screw and the screw avoidance hole cooperate to prevent the fixed wheel 6 from rotating.

[0046] The friction ring 7 includes a spline groove 7-1 and a second friction portion 7-2; preferably, the second friction portion 7-2 is a second friction slope; two second friction slopes are symmetrically arranged on both sides of the friction ring 7; the second friction slope is adapted to the shape of the first friction slope. The friction ring 7 is made of an elastic material with high wear resistance, preferably an alloy, or POM or HDPE with built-in steel wire.

[0047] The flexible wheel 8 includes a base 8-1, a connecting column 8-2 and a spline 8-3, and the base 8-1, the connecting column 8-2 and the spline 8-3 can be processed and manufactured in one piece. The base 8-1 is a thin-walled cylinder, which can produce elastic deformation under the action of external force. The base 8-1 is made of an elastic material with high wear resistance. The material elasticity of the base 8-1 is greater than the material elasticity of the friction ring 7, and is preferably rubber or TPU or TPV with built-in tire wire and / or steel wire. The inner circumferential surface of the base 8-1 is a smooth surface, and the roller 5-2 abuts on the inner circumferential surface of the base 8-1. A plurality of connecting columns 8-2 are evenly spaced and distributed on one side end face of the base 8-1 in a circular distribution; the spline 8-3 is arranged on the outer circumferential surface of the base 8-1, and the spline 8-3 can be inserted into the spline groove 7-1 to realize the transmission connection between the friction ring 7 and the flexible wheel 8. Of course, in addition to the spline connection provided in this embodiment, the friction ring 7 and the flexible wheel 8 can also be fixedly connected by bonding or tight fitting.

[0048] The output assembly includes an output disk 9 and an output shaft 10. The output disk 9 is provided with a column hole 9-1 corresponding to the connecting column 8-2. The connecting column 8-2 is inserted into the column hole 9-1. The connecting column 8-2 can only move relative to the output disk 9 along the radial direction of the output disk 9 under the restriction of the column hole 9-1, that is, the connecting column 8-2 can drive the output disk 9 to rotate.

[0049] The output disc 9 is also provided with a large circular spline hole 9-2. The output shaft 10 is provided with a circular spline block 10-1 whose shape matches the large circular spline hole 9-2. The circular spline block 10-1 is inserted into the large circular spline hole 9-2 in a shape-matched manner, so that the output disc 9 can drive the output shaft 10 to rotate as a whole. The output shaft 10 also includes a shaft 10-2, which is rotatably supported on the shell cover 4 through the bearing 4-1 and extends out of the shell cover 4 to serve as the output end of the entire harmonic reducer.

[0050] According to the harmonic reducer provided in this embodiment, the two stators 6 are symmetrically arranged on both sides of the middle shell 3 through the positioning parts 6-1; a friction cavity is formed between the first friction inclined surfaces of the two stators 6; and the friction ring 7 is arranged in the friction cavity. A first friction meshing angle is formed between the first friction inclined surfaces of the two stators 6; a second friction meshing angle is formed between the second friction inclined surfaces on both sides of the friction ring 7, and the angle value of the second friction meshing angle is the same as that of the first friction meshing angle.

[0051] When the friction ring 7 is coaxially arranged with the fixed wheel 6 without external force, the friction ring 7 does not contact the fixed wheel 6, and there is a certain gap between the second friction slope and the first friction slope. When the wave generator assembly 5 is installed in the flexible wheel 8, the roller 5-2 in the wave generator assembly 5 squeezes the base 8-1. The base 8-1 is squeezed and deformed into an elliptical shape by the wave generator assembly 5, and then the friction ring 7 arranged on the outside of the base 8-1 is deformed into an elliptical shape. The gap between the second friction slope at the two ends of the long axis of the elliptical friction ring 7 and the first friction slope of the fixed wheel becomes larger; the second friction slope at the two ends of the short axis of the elliptical friction ring 7 is in contact with the first friction slope of the fixed wheel, generating friction.

[0052] When the wave generator assembly 5 rotates, the two endpoints of the long axis and the two endpoints of the short axis of the elliptical friction ring 7 change accordingly with the wave generator assembly 5, that is, the friction position between the friction ring 7 and the fixed wheel 6 rotates with the wave generator assembly 5, thereby realizing the movement of the friction ring 7 relative to the fixed wheel 6.

[0053] The pitch diameter at the second friction slope of the friction ring 7 is D, the pitch diameter at the first friction slope of the fixed wheel 6 is d, and the length that the friction ring 7 can move on the fixed wheel 6 for each rotation is π (Dd), so the reduction ratio of the harmonic reducer is Specifically, when D is 50 mm and d is 49.5 mm, the reduction ratio of the harmonic reducer is 50 / (50-49.5)=100.

[0054] The harmonic reducer and driver provided in this embodiment have the following working principles: when the motor 1 rotates, the motor output shaft drives the wave generator assembly 5 to rotate, and the rollers 5-2 on both sides of the wave generator assembly 5 abut against the inner wall of the base 8-1 of the flexible wheel 8, so that the base 8-1 undergoes elliptical deformation, and then the friction ring 7 arranged on the outer side of the base 8-1 undergoes synchronous deformation; the second friction inclined surfaces at the two ends of the short axis of the elliptical friction ring 7 contact the first friction inclined surface of the fixed wheel 6, and produce friction engagement; as the wave generator assembly 5 rotates, the contact point between the friction ring 7 and the fixed wheel 6 continuously changes position, so that the friction ring 7 produces relative movement relative to the fixed wheel 6, so that the friction ring 7 can rotate, and the direction of rotation is the same as the direction of rotation of the wave generator assembly 5. Since the friction ring 7 is fixedly connected to the flexible wheel 8, the connecting column 8-2 of the flexible wheel 8 is inserted into the column hole 9-1 of the output disk 9, and the output shaft 10 is connected to the output disk 9 through a large circular spline; thereby driving the output shaft 10 to rotate.

[0055] The reduction ratio of the flexspline 8 to the wave generator assembly 5 is the ratio of the pitch diameter D at the second friction slope to the difference between the pitch diameter D at the second friction slope and the pitch diameter d at the first friction slope. In this embodiment, the flexspline and the stator are not harmonic reduction transmission by tooth meshing as in the traditional harmonic reducer, but reduction transmission is achieved by friction between the friction ring and the stator, that is, the output shaft is reduced relative to the motor output shaft by a toothless harmonic reduction method.

[0056] Embodiment 2

[0057] like Figure 10-12 As shown, in this embodiment, the wave generator assembly 5, the fixed wheel 6 and the friction ring 7 in the harmonic reducer are provided with two groups, the base of the flexible wheel 8 is provided with two groups of splines 8-3, and the two friction rings 7 are arranged on the base 8-1 at intervals through the splines 8-3; a connecting ring 3-1 is provided between the two middle shells 3, and the connecting ring 3-1 is also provided with a screw avoidance hole 2 for the connecting screw to pass through, and the rest is the same as the first embodiment, which will not be repeated here. The two groups of fixed wheels 6 and friction rings 7 can enhance the output power and torque of the harmonic reducer.

[0058] Of course, the wave generator assembly, stator and friction ring in this embodiment can be arranged into more than two groups according to actual working conditions.

[0059] Compared with the prior art, the toothless harmonic reducer and driver provided by the present invention have the following advantages:

[0060] Since toothless harmonic reduction is performed through the friction drive principle, the disadvantage of low transmission efficiency caused by deformation of flexible wheel teeth in traditional toothed harmonic reduction is overcome, and the transmission efficiency of the harmonic reducer is greatly improved; in addition, since the input shaft and output shaft of the harmonic reducer in the present application rotate in the same direction, the harmonic transmission efficiency is also improved.

[0061] The flexible wheel and the friction ring are set separately, and the transmission efficiency and output torque of the harmonic reducer can be adjusted conveniently by changing the elasticity and hardness of the materials of the flexible wheel and the friction ring. The friction ring can be made of a highly wear-resistant material with a relatively high hardness, which can improve the output torque of the harmonic reducer. The flexible wheel can be made of a highly wear-resistant material with a relatively high elasticity, which is easy to produce harmonic deformation; the high wear resistance of the flexible wheel can reduce the impact caused by roller friction and increase the service life of the harmonic reducer.

[0062] The output disc and the output shaft are connected by spline, which can realize zero-backlash transmission and does not require other connecting parts. It is easy to install and greatly simplifies the structure of the harmonic reducer.

[0063] The bottom shell, the middle shell and the shell cover are connected and installed through screws, which has a simple structure, is easy to install and reduces costs. The screw avoidance hole on the fixed wheel cooperates with the screw to effectively limit the position and prevent the fixed wheel from rotating.

[0064] The wave generator assembly, the fixed wheel and the friction ring can be set to more than two groups according to the actual working conditions, which is convenient for expansion to improve the output power and output torque of the harmonic reducer.

[0065] In summary, the present invention proposes a toothless harmonic reducer and driver with stable and reliable transmission, high efficiency and precision, and low cost, which has broad application prospects in the field of robotics.

[0066] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and assemble different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

Claims

1. A toothless harmonic reducer, comprising a wave generator assembly, a stator, a flexible wheel and a friction ring, characterized in that: The friction ring is arranged on the flexible wheel; the wave generator assembly is arranged in the flexible wheel, and the wave generator assembly actuates the flexible wheel and the friction ring to synchronously deform into an ellipse; at two short axis endpoints of the ellipse-shaped friction ring, the friction ring contacts the fixed wheel, and at two long axis endpoints of the ellipse-shaped friction ring, the friction ring does not contact the fixed wheel; The flexible wheel comprises a base body, the base body is a thin-walled cylinder, the inner circumferential surface of the base body is a smooth surface, the wave generator assembly abuts against the inner circumferential surface; the friction ring is arranged on the outer circumferential surface of the base body; The base is provided with a spline; the friction ring is provided with a spline groove; the friction ring and the base are connected through the spline and the spline groove; The material elasticity of the flexible wheel is greater than the material elasticity of the friction ring; It also includes an output assembly, which includes an output disc and an output shaft; the output disc is provided with a large circular spline hole, the output shaft is provided with a circular spline block, and the circular spline block can be inserted into the large circular spline hole in a shape-matched manner; The output shaft further comprises a shaft rod which is rotatably supported on the housing cover through a bearing and extends out of the housing cover.

2. The toothless harmonic reducer according to claim 1, characterized in that: A connecting column is arranged on one end surface of the base body; a column hole is arranged on the output disk; the connecting column is inserted into the column hole, and the connecting column can only move relative to the output disk along the radial direction of the output disk under the restriction of the column hole.

3. The toothless harmonic reducer according to claim 2, characterized in that: It also includes a shell assembly, which includes a bottom shell, a middle shell and a shell cover; the middle shell is arranged between the bottom shell and the shell cover; the bottom shell, the middle shell and the shell cover are connected in sequence by connecting screws; a screw avoidance hole is arranged on the fixed wheel, and the connecting screw passes through the screw avoidance hole.

4. The toothless harmonic reducer according to claim 3, characterized in that: The fixed wheel is ring-shaped, and includes a positioning portion and a first friction portion. The fixed wheel is arranged on both sides of the middle shell through the positioning portion, and a friction cavity is formed between the first friction portions on both sides; the friction ring is arranged in the friction cavity; the friction ring includes a symmetrically arranged second friction portion; the contact between the friction ring and the fixed wheel is the contact between the first friction portion and the second friction portion.

5. A toothless harmonic reducer, comprising a wave generator assembly, a fixed wheel assembly, a flexible wheel and a friction ring, characterized in that: More than two friction rings are arranged on the flexible wheel at intervals; more than two wave generator assemblies are arranged in the flexible wheel, and the wave generator assembly actuates the flexible wheel and the friction ring to synchronously deform into an ellipse; at the two short axis ends of the ellipse-shaped friction ring, the friction ring contacts the fixed wheel assembly, and at the two long axis ends of the ellipse-shaped friction ring, the friction ring does not contact the fixed wheel assembly; the number of the wave generator assemblies, the fixed wheel assembly and the friction ring is the same; The flexible wheel comprises a base body, the base body is a thin-walled cylinder, the inner circumferential surface of the base body is a smooth surface, the wave generator assembly abuts against the inner circumferential surface; the friction ring is arranged on the outer circumferential surface of the base body; The base is provided with a spline; the friction ring is provided with a spline groove; the friction ring and the base are connected through the spline and the spline groove; The material elasticity of the flex spline is greater than the material elasticity of the friction ring.

6. A driver, comprising a motor and a harmonic reducer according to any one of claims 1 to 5, characterized in that: The harmonic reducer is installed at the output end of the motor.

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