Cam, wave generator and harmonic reducer

Abstract

The invention provides a cam, a wave generator and a harmonic reducer, the cam comprises a cam body, a material reduction area is arranged on the peripheral side face of the cam body, the material reduction area comprises a wavy surface section, and in the section where the axis of the cam body is located, the wavy surface section is in a wavy line shape extending in the axial direction of the cam body; the subtractive areas are continuously or discontinuously distributed in the circumferential direction of the cam body, and after the cam is matched with the flexible bearing, buffer spaces capable of providing elastic deformation and absorbing vibration are formed in the subtractive areas. According to the arrangement, the cam of the wave surface section is designed and constructed in the material reduction area, the self balance weight is reduced, the contact area between the cam and the flexible bearing is reduced, the cam has better structural mechanical performance, in the operation process of the harmonic reducer, a buffer space for providing elastic deformation and absorbing vibration is formed in the material reduction area, and the vibration reduction effect is improved. Load distribution of the harmonic reducer in the operation process is more uniform, and high-speed, low-noise and small-vibration operation of the harmonic reducer is facilitated.

Description

Technical Field

[0001] The present application relates to the technical field of harmonic reducers, and in particular to a cam, a wave generator and a harmonic reducer. Background Art

[0002] A harmonic reducer is a gear transmission structure that relies on a wave generator equipped with a flexible bearing to make the flexible wheel produce controllable elastic deformation and mesh with the rigid wheel to transmit motion and power. The wave generator consists of a cam and a flexible bearing, and the outer contour of the cam is usually elliptical.

[0003] In recent years, with the rapid development of the robotics industry, especially the updating and iteration of collaborative robots and humanoid robots, the requirements for harmonic reducers used in robots have gradually increased. However, the performance of harmonic reducers in the existing technology in terms of light weight, high speed, low noise and low vibration is difficult to meet the design requirements of robots.

[0004] Therefore, it is particularly important to optimize the structure of the harmonic reducer to improve its performance in terms of light weight, high speed, low noise and low vibration. Summary of the invention

[0005] In view of this, the present application provides a cam, a wave generator and a harmonic reducer to solve the problem in the prior art of how to optimize the structure of the harmonic reducer to improve the performance in terms of light weight, high speed, low noise and low vibration.

[0006] In order to achieve the above objectives, this application provides the following technical solutions: A cam, applied to a harmonic reducer, comprises a cam body, a material reduction area is provided on the peripheral side surface of the cam body, the material reduction area comprises a wave surface segment, and in a cross section where the axis of the cam body is located, the wave surface segment is in the shape of a wave line extending along the axial direction of the cam body; The material reduction area is distributed continuously or discontinuously along the circumference of the cam body. After the cam is matched with the flexible bearing, a buffer space capable of providing elastic deformation and absorbing vibration is formed in the material reduction area.

[0007] Optionally, the material reduction zone further includes a first inclined surface segment and a second inclined surface segment, and in the axial direction of the cam body, the first inclined surface segment and the second inclined surface segment are respectively located on both sides of the wave surface segment; In the cross section where the axis of the cam body is located, the first inclined surface segment and the second inclined surface segment are both in the shape of an oblique line, and are both inclined from one side connected to the wave surface segment to the other side toward the direction close to the axis of the cam body.

[0008] Optionally, the first inclined surface segment is located on a first side of the wave surface segment, the second inclined surface segment is located on a second side of the wave surface segment, the first side of the wave surface segment is on the same side as the output side of the harmonic reducer, and the second side of the wave surface segment is on the same side as the input side of the harmonic reducer; wherein, The projection size of the first inclined surface segment in the axial direction of the cam body is h1, and the projection size of the second inclined surface segment in the axial direction of the cam body is h2, where h1≤h2; And / or, the angle between the extended surface where the first inclined surface segment is located and the axis of the cam body is α, the angle between the extended surface where the second inclined surface segment is located and the axis of the cam body is β, α≤β.

[0009] Optionally, in the cross section where the axis of the cam body is located, the axial length of the cam body is H, the projection size of the wave surface segment on the axial direction of the cam body is h, the radii of the multiple arc surface segments constituting the wave surface segment are all R, the projection size of the first inclined surface segment on the axial direction of the cam body is h1, and the projection size of the second inclined surface segment on the axial direction of the cam body is h2, wherein: h and R are positively correlated; H=h+h1+h2, h and h1+h2 are negatively correlated.

[0010] Optionally, the wave surface segment includes a first concave arc surface segment, a first convex arc surface segment, a second concave arc surface segment, a second convex arc surface segment and a third concave arc surface segment which are sequentially distributed along the axial direction of the cam body.

[0011] Optionally, in the cross section where the axis of the cam body is located, the axial length of the cam body is H, the projection size of the first inclined surface segment in the axial direction of the cam body is h1, the projection size of the second inclined surface segment in the axial direction of the cam body is h2, and the radii of the first concave arc surface segment, the first convex arc surface segment, the second concave arc surface segment, the second convex arc surface segment and the third concave arc surface segment are all R, wherein: H=h1+h2+a×5×R, 0.59≤a≤0.64.

[0012] Optionally, a takes the value 0.6204.

[0013] Optionally, the radii of the multiple arc surface segments constituting the wave surface segment are all R; The outer diameter of the cam body at the most convex point of the wave surface segment is D, and the outer diameter of the most concave point of the wave surface segment is d, wherein: There is a negative correlation between R and D, and a positive correlation between R and d.

[0014] Optionally, the outer diameter of the cam body at the most convex point of the wave surface segment is D, and the outer diameter of the most concave point of the wave surface segment is d; The depth of the most concave point of the wave surface segment relative to the most convex point is d1, where: D=d+2×d1.

[0015] Optionally, the angle between the extended surface where the first inclined surface segment is located and the axis of the cam body is α, the angle between the extended surface where the second inclined surface segment is located and the axis of the cam body is β, 1°≤α≤5°, 1°≤β≤5°.

[0016] Optionally, both ends of the cam body in the axial direction are provided with chamfers, and the chamfers are connected to the corresponding first inclined surface segment or the second inclined surface segment.

[0017] A wave generator comprises a flexible bearing and any one of the above cams, wherein the flexible bearing is sleeved on the cam.

[0018] A harmonic reducer comprises a rigid wheel, a flexible wheel and the above-mentioned wave generator.

[0019] The cam provided in the present application is applied to a harmonic reducer, and includes a cam body. A material reduction zone is provided on the circumferential side surface of the cam body. The material reduction zone includes a wave surface segment. In the cross section where the axis of the cam body is located, the wave surface segment is in the shape of a wave line extending along the axial direction of the cam body. The material reduction zone is continuously or discontinuously distributed along the circumference of the cam body. After the cam is matched with the flexible bearing, a buffer space that can provide elastic deformation and absorb vibration is formed in the material reduction zone. In this way, the circumferential side surface of the cam body is the surface of the cam used to cooperate with the flexible bearing, that is, the outer contour of the cam. There is a design with local material missing on the circumferential side surface of the cam body to form a reduced material area. After many experiments and verifications, the applicant found that designing and constructing a cam with a wave surface segment in the reduced material area not only reduces its own counterweight and reduces the contact area with the flexible bearing, so that the cam has better structural mechanical properties, but also during the operation of the harmonic reducer, a buffer space is formed in the reduced material area to provide elastic deformation and absorb vibration, so that the load distribution of the harmonic reducer during operation is more uniform, which is conducive to the high-speed, low-noise and low-vibration operation of the harmonic reducer. Compared with the conventional cams in the prior art, the cam provided by the present application can meet the performance requirements in terms of lightweight, high speed, low noise and low vibration, and solves the problem of how to optimize the structure of the harmonic reducer in the prior art to improve the performance in terms of lightweight, high speed, low noise and low vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of the structure of the cam provided in an embodiment of the present application.

[0022] Figure 2 A schematic diagram of the cross-sectional structure of the cam provided in an embodiment of the present application.

[0023] Figure 3 for Figure 2 Partial schematic diagram at point A in the middle.

[0024] Figure 4 for Figure 2 The dimension marking diagram at A in the middle.

[0025] exist Figure 1-Figure 4 middle: 1. Cam body; 11. Material reduction area; 12. Chamfering; 111, wavy surface segment; 112, first inclined surface segment; 113, second inclined surface segment. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] The applicant has found that the cam, as a power component of the harmonic reducer, has a very important influence on the performance of the harmonic reducer in terms of its structural design and size parameters.

[0028] like Figure 1-Figure 4 As shown, an embodiment of the present application provides a cam, which is applied to a harmonic reducer, including a cam body 1, and a material reduction area 11 is provided on the circumferential side surface of the cam body 1, and the material reduction area 11 includes a wave surface segment 111. In the cross section where the axis of the cam body 1 is located, the wave surface segment 111 is in the shape of a wave line extending along the axial direction of the cam body 1; the material reduction area 11 is continuously or discontinuously distributed along the circumference of the cam body 1, that is, the material reduction area 11 is a coherent area surrounding the entire circumference or a non-coherent area distributed in multiple sections at intervals. After the cam is matched with the flexible bearing, a buffer space that can provide elastic deformation and absorb vibration is formed in the material reduction area 11.

[0029] In this way, the circumferential side surface of the cam body 1 is the surface of the cam used to cooperate with the flexible bearing, that is, the outer contour of the cam. There is a design with local material missing on the circumferential side surface of the cam body 1, and a reduced material area 11 is formed. After many experiments and verifications, the applicant found that the cam with a wave surface segment 111 designed and constructed in the reduced material area 11 not only reduces its own counterweight, reduces the contact area with the flexible bearing, and makes the cam have better structural mechanical properties, but also forms a buffer space in the reduced material area 11 during the operation of the harmonic reducer, which provides elastic deformation and absorbs vibration, so that the load distribution of the harmonic reducer during operation is more uniform, which is conducive to the high-speed, low-noise and low-vibration operation of the harmonic reducer. Compared with the conventional cam in the prior art, the cam provided by the present application can meet the performance requirements of lightweight, high-speed, low-noise and low-vibration, and solves the problem of how to optimize the structure of the harmonic reducer in the prior art to improve the performance in terms of lightweight, high-speed, low-noise and low-vibration.

[0030] This application abandons the inherent design ideas for cams in this field. In the long-term product development and improvement practice, various cam structure designs are studied to explore the impact on the performance of harmonic reducers, and the circumferential side of the cam is designed to be a wavy surface, which is a completely different material reduction design from the past. Through breakthrough design in details, after the cam is assembled to the harmonic reducer, the performance of the harmonic reducer in many of the above aspects is improved, and outstanding technical effects are achieved through completely different design ideas.

[0031] Moreover, the cam provided in this application has been tested and verified to have good performance in the application of small harmonic reducers, which is helpful for the design direction of miniaturization of harmonic reducers.

[0032] In the present application, it is preferably designed that the material reduction area 11 is continuously distributed on the peripheral side surface of the cam body 1 .

[0033] In addition, in some specific embodiments, when the material reduction area 11 is designed to be intermittently distributed on the peripheral side of the cam body 1, both ends of each section of the material reduction area 11 are connected to the outer surface of the cam body 1 through a transition curved surface.

[0034] In some preferred embodiments, the material reduction area 11 further includes a first bevel segment 112 and a second bevel segment 113. In the axial direction of the cam body 1, the first bevel segment 112 and the second bevel segment 113 are respectively located on both sides of the wave surface segment 111; in the cross section where the axis of the cam body 1 is located, the first bevel segment 112 and the second bevel segment 113 are both in the shape of an oblique line, and both are inclined from one side connected to the wave surface segment 111 to the other side in a direction close to the axis of the cam body 1. That is, the first bevel segment 112 and the second bevel segment 113 form a material reduction design that is different in shape from the wave surface segment 111.

[0035] With such an arrangement, based on the design of the wavy surface segment 111 in the material reduction area 11, a design with inclined surface segments on both sides is further formed. After testing and verification, it can further reduce the cam's own counterweight and reduce the contact area between the cam and the flexible bearing, thereby further improving the structural mechanical properties of the cam, and further improving the performance of the cam in terms of helping the harmonic reducer to be lightweight, high-speed, low-noise, and low-vibration.

[0036] In some specific embodiments, the first bevel segment 112 is located on the first side of the wave surface segment 111, and the second bevel segment 113 is located on the second side of the wave surface segment 111, the first side of the wave surface segment 111 is on the same side as the output side of the harmonic reducer, and the second side of the wave surface segment 111 is on the same side as the input side of the harmonic reducer; wherein, the projection dimension of the first bevel segment 112 in the axial direction of the cam body 1 is h1, and the projection dimension of the second bevel segment 113 in the axial direction of the cam body 1 is h2, h1≤h2; and / or, the angle between the extended surface of the first bevel segment 112 and the axis of the cam body 1 is α, and the angle between the extended surface of the second bevel segment 113 and the axis of the cam body 1 is β, α≤β.

[0037] With such arrangement, the first bevel section 112 and the second bevel section 113 can be designed to be a symmetrical structure, that is, h1=h2 and α=β; and the load size and working conditions on the inner and outer sides of the cam are generally different, so the first bevel section 112 and the second bevel section 113 can also be designed to be an asymmetrical structure. Since the second bevel section 113 and the input side of the harmonic reducer are on the same side, it is preferred to set the second bevel section 113 to be longer in axial dimension than the first bevel section 112, and the inclination angle of the second bevel section 113 is also larger than the inclination angle of the first bevel section 112, that is, h2>h1, β>α, which is conducive to the cam having better structural mechanical properties.

[0038] The design parameter values ​​of the cam body 1 are not arbitrary, but need to follow a certain design basis, so as to ensure the structural strength while achieving the desired technical effect of optimizing the performance of the harmonic reducer.

[0039] In some specific embodiments, in the cross-section where the axis of the cam body 1 is located, the axial length of the cam body 1 is H, the projection size of the wave surface segment 111 on the axial direction of the cam body 1 is h, the radii of the multiple arc surface segments constituting the wave surface segment 111 are all R, the projection size of the first inclined surface segment 112 on the axial direction of the cam body 1 is h1, and the projection size of the second inclined surface segment 113 on the axial direction of the cam body 1 is h2, wherein: h and R are positively correlated, that is, the larger R is, the larger the design value of h is; H=h+h1+h2, h and h1+h2 are negatively correlated, that is, the larger R is, the larger h is, and the smaller the design value of h1+h2 is.

[0040] With such arrangement, on the one hand, the projection size of the wave surface segment 111 in the axial direction is the chord length corresponding to the arc surface segment, and there is a known calculation formula between the chord length, R, and the center angle corresponding to the arc surface segment, that is, the chord length is affected by R and the center angle. When designing the specific parameters of the wave surface segment 111, it should be ensured that the center angle corresponding to the arc surface segment is a certain value or a small design range, preferably an obtuse angle. Following such a design, the larger the R value is, the larger the design value of h is, and the undulation degree and distribution range of the wave surface segment 111 are adapted. With such a design of the material reduction zone 11, the cam can achieve a better level of load uniformity during the operation of the harmonic reducer; on the other hand, the axial length H of the cam body 1 should be within a certain design range, so when h is larger, the design value of h1+h2 is smaller, ensuring that the axial length H of the cam body 1 is adapted to the axial length of the flexible bearing.

[0041] More specifically, the number of arc surface segments constituting the wave surface segment 111 can be 2, 3, 4, 5, or 6.

[0042] In some preferred embodiments, the number of arc surface segments constituting the wave surface segment 111 is selected to be 5, and the wave surface segment 111 includes a first concave arc surface segment, a first convex arc surface segment, a second concave arc surface segment, a second convex arc surface segment, and a third concave arc surface segment distributed in sequence along the axial direction of the cam body 1. In this way, after testing and verification, when the wave surface segment 111 of the cam has five arc surface segments, it is easy to design the values ​​of R, h, h1, and h2, and after the cam is assembled in the harmonic reducer, the harmonic reducer obtains a better load distribution uniformity effect during operation.

[0043] Furthermore, in some specific embodiments, in the cross-section where the axis of the cam body 1 is located, the axial length of the cam body 1 is H, the axial projection size of the first bevel segment 112 on the cam body 1 is h1, the axial projection size of the second bevel segment 113 on the cam body 1 is h2, and the radii of the first concave arc segment, the first convex arc segment, the second concave arc segment, the second convex arc segment and the third concave arc segment are all R, where: H=h1+h2+a×5×R, 0.59≤a≤0.64.

[0044] With such arrangement, after various optimal designs of the parameters of the cam body 1 and the material reduction zone 11, the above relationship is obtained through simulation.

[0045] More preferably, the value of a is 0.6204.

[0046] In some other specific embodiments, the radii of the multiple arc segments constituting the wave surface segment 111 are all R; the outer diameter of the cam body 1 at the most convex point of the wave surface segment 111 is D, and the outer diameter at the most concave point of the wave surface segment 111 is d, wherein: R and D are negatively correlated, and R and d are positively correlated. That is, the larger R is, the smaller D is, and the larger d is. It should be noted that the outer contour of the cam body 1 is elliptical, and the above relationship is met in any cross section where the axis of the cam body 1 is located.

[0047] Such setting and design according to the above-mentioned method conform to the rule that the larger R is, the smaller the fluctuation of the wave surface segment 111 is. Following such a design, in experiments and verifications, after the cam is assembled in the harmonic reducer, the harmonic reducer obtains better load distribution uniformity during operation.

[0048] In some other specific embodiments, the outer diameter of the cam body 1 at the most convex point of the wave surface segment 111 is D, and the outer diameter at the most concave point of the wave surface segment 111 is d; the depth of the most concave point of the wave surface segment 111 relative to the most convex point is d1, where: D=d+2×d1. It should be noted that the outer contour of the cam body 1 is elliptical, and the above relationship is met in any cross section where the axis of the cam body 1 is located.

[0049] With such arrangement, the lowest point of each wave surface segment 111 is on the same ellipse, the highest point of each wave surface segment 111 is on the same ellipse, and the position of the material reduction area 11 in each position in the wave surface segment 111 is highly consistent, ensuring that after the cam is assembled in the harmonic reducer, the uniformity of load distribution of the harmonic reducer during operation is improved.

[0050] In some other specific embodiments, the angle between the extended surface where the first bevel segment 112 is located and the axis of the cam body 1 is α, the angle between the extended surface where the second bevel segment 113 is located and the axis of the cam body 1 is β, 1°≤α≤5°, 1°≤β≤5°. In this way, the inclination angles of the bevel segments on both sides of the wave surface segment 111 are controlled within the above-mentioned angle range, and with the surface profile design of the material reduction area 11, better cam performance can be obtained.

[0051] In some other preferred embodiments, both ends of the cam body 1 in the axial direction are provided with chamfers 12, and the chamfers 12 are connected to the corresponding first inclined surface section 112 or second inclined surface section 113. In this way, the outer edge of the end surface of the cam body 1 is provided with a chamfer 12, which facilitates the installation and removal of the cam in the harmonic reducer.

[0052] Based on the above cam, the embodiment of the present application further provides a wave generator, which includes a flexible bearing and the above cam, and the flexible bearing is sleeved on the cam. Since the wave generator has the above cam, the beneficial effects of the wave generator brought by the cam can be seen in the above content, which will not be repeated here.

[0053] Based on the above-mentioned wave generator, the embodiment of the present application further provides a harmonic reducer, which includes a rigid wheel, a flexible wheel and the above-mentioned wave generator, wherein the wave generator is sleeved inside the flexible wheel, the flexible wheel is sleeved inside the rigid wheel, and the flexible wheel and the rigid wheel are meshed with teeth. Since the harmonic reducer has the above-mentioned wave generator, the beneficial effects of the harmonic reducer brought by the wave generator can be found in the above content, which will not be repeated here.

[0054] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0055] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0056] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0057] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0058] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0059] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A cam, characterized in that: The invention is applied to a harmonic reducer, comprising a cam body (1), wherein a material reduction area (11) is provided on a peripheral side surface of the cam body (1), wherein the material reduction area (11) comprises a wave surface segment (111), and in a cross section where the axis of the cam body (1) is located, the wave surface segment (111) is in the shape of a wave line extending along the axial direction of the cam body (1); The material reduction area (11) is distributed continuously or discontinuously along the circumference of the cam body (1); after the cam is matched with the flexible bearing, a buffer space capable of providing elastic deformation and absorbing vibration is formed in the material reduction area (11).

2. The cam according to claim 1, characterized in that: The material reduction zone (11) further comprises a first inclined surface segment (112) and a second inclined surface segment (113); in the axial direction of the cam body (1), the first inclined surface segment (112) and the second inclined surface segment (113) are respectively located on both sides of the wave surface segment (111); In the cross section where the axis of the cam body (1) is located, the first inclined surface segment (112) and the second inclined surface segment (113) are both in the shape of an oblique line, and both are inclined from one side connected to the wave surface segment (111) to the other side in a direction close to the axis of the cam body (1).

3. The cam according to claim 2, characterized in that: The first inclined surface segment (112) is located on a first side of the wave surface segment (111), the second inclined surface segment (113) is located on a second side of the wave surface segment (111), the first side of the wave surface segment (111) is on the same side as the output side of the harmonic reducer, and the second side of the wave surface segment (111) is on the same side as the input side of the harmonic reducer; wherein: The projection size of the first inclined surface segment (112) in the axial direction of the cam body (1) is h1, and the projection size of the second inclined surface segment (113) in the axial direction of the cam body (1) is h2, where h1≤h2; And / or, the angle between the extended surface where the first inclined surface segment (112) is located and the axis of the cam body (1) is α, and the angle between the extended surface where the second inclined surface segment (113) is located and the axis of the cam body (1) is β, α≤β.

4. The cam according to claim 2, characterized in that: In a cross section where the axis of the cam body (1) is located, the axial length of the cam body (1) is H, the projection dimension of the wave surface segment (111) on the axial direction of the cam body (1) is h, the radii of the plurality of arc surface segments constituting the wave surface segment (111) are all R, the projection dimension of the first inclined surface segment (112) on the axial direction of the cam body (1) is h1, and the projection dimension of the second inclined surface segment (113) on the axial direction of the cam body (1) is h2, wherein: h and R are positively correlated; H=h+h1+h2, h and h1+h2 are negatively correlated.

5. The cam according to claim 2, characterized in that: The wave surface segment (111) comprises a first concave arc surface segment, a first convex arc surface segment, a second concave arc surface segment, a second convex arc surface segment and a third concave arc surface segment, which are sequentially distributed along the axial direction of the cam body (1).

6. The cam according to claim 5, characterized in that: In a cross section where the axis of the cam body (1) is located, the axial length of the cam body (1) is H, the projection size of the first inclined surface segment (112) on the axial direction of the cam body (1) is h1, the projection size of the second inclined surface segment (113) on the axial direction of the cam body (1) is h2, and the radii of the first concave arc surface segment, the first convex arc surface segment, the second concave arc surface segment, the second convex arc surface segment and the third concave arc surface segment are all R, wherein: H=h1+h2+a×5×R, 0.59≤a≤0.

64.

7. The cam according to claim 6, characterized in that: The value of a is 0.6204.

8. The cam according to claim 2, characterized in that: The radii of the multiple arc surface segments constituting the wave surface segment (111) are all R; The outer diameter of the cam body (1) at the most convex point of the wave surface segment (111) is D, and the outer diameter of the most concave point of the wave surface segment (111) is d, wherein: There is a negative correlation between R and D, and a positive correlation between R and d.

9. The cam according to claim 2, characterized in that: The outer diameter of the cam body (1) at the most convex point of the wave surface segment (111) is D, and the outer diameter of the most concave point of the wave surface segment (111) is d; The depth of the most concave point of the wave surface segment (111) relative to the most convex point is d1, wherein: D=d+2×d1.

10. The cam according to claim 2, characterized in that: The angle between the extended surface where the first inclined surface segment (112) is located and the axis of the cam body (1) is α, and the angle between the extended surface where the second inclined surface segment (113) is located and the axis of the cam body (1) is β, 1°≤α≤5°, 1°≤β≤5°.

11. The cam according to claim 2, characterized in that: The cam body (1) is provided with chamfers (12) at both ends in the axial direction, and the chamfers (12) are connected to the corresponding first inclined surface segment (112) or the second inclined surface segment (113).

12. A wave generator, characterized in that: It comprises a flexible bearing and a cam as described in any one of claims 1 to 11, wherein the flexible bearing is sleeved on the cam.

13. A harmonic reducer, characterized in that: It comprises a rigid wheel, a flexible wheel and the wave generator as claimed in claim 12.

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