Rigid-flexible composite two-stage cycloid planetary reducer

Abstract

The invention relates to a rigid-flexible composite two-stage cycloid planetary reducer, and belongs to the technical field of mechanical transmission. Comprising an output small gear (1), a rigid-flexible compound gear (18), a fixed large gear (7), an input end eccentric sleeve (3) and an output end eccentric sleeve (12). The left end of a speed reducer output pinion (1) is connected with an input end eccentric sleeve (3), a rigid-flexible compound gear (18) and a fixed large gear (7) through three deep groove ball bearings, the right end of the output pinion (1) is matched with an output end eccentric sleeve (12), the rigid-flexible compound gear (18) and the fixed large gear (7) through three deep groove ball bearings, and flexible body units are evenly distributed on the inner circumference of the rigid-flexible compound gear (18). The invention has the advantages of simple and compact structure, high bearing capacity, high power density, stable transmission and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical transmission and relates to a rigid-flexible composite two-stage cycloid planetary reducer. Background Art

[0002] As a key component for power transmission and motion conversion, gear transmission mechanisms are widely used in aerospace, construction, metallurgy, defense industry and other fields. As the requirements for volume and quality of electromechanical equipment become more and more stringent, gear transmission mechanisms not only require high processing accuracy, but also need to have the characteristics of high output power, large torque and smooth transmission under limited volume and mass. However, the planetary reducers with small tooth difference commonly used in industry have fewer meshing tooth pairs, resulting in low overlap, the flexible wheel of the harmonic reducer is prone to fatigue damage, resulting in a short life, and the RV reducer is large in size and has a large number of parts. Therefore, these reducers cannot fully meet the current industrial development needs of large speed ratio, lightweight and high power density. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a rigid-flexible composite two-stage cycloid planetary reducer, which arranges the two-stage planetary reduction on the same plane to shorten the axial structural size, thereby reducing the overall structural size and weight of the reducer, and adopts a cycloid needle roller meshing pair to increase the number of simultaneously meshing tooth pairs and reduce friction loss power, thereby improving the load-bearing capacity and transmission efficiency. Rigid-flexible composite gears are used to make the cycloid gears have a certain degree of flexibility while ensuring accuracy and transmitting torque, which is used to resist errors caused by processing and manufacturing and increase the smoothness of transmission.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A rigid-flexible composite two-stage cycloid planetary reducer, comprising an output pinion, a rigid-flexible composite gear, a fixed large gear, an input end eccentric sleeve, and an output end eccentric sleeve;

[0006] The eccentric sleeve at the input end is coaxially matched with the input end shaft section of the output pinion through the input end primary bearing, the eccentric cylindrical surface of the eccentric sleeve at the input end is coaxially matched with the rigid-flexible composite gear through the input end secondary bearing, the eccentric sleeve at the input end is coaxially matched with the fixed large gear through the input end tertiary bearing, the eccentric sleeve at the output end is coaxially matched with the output end shaft section of the output pinion through the output end primary bearing, the eccentric cylindrical surface of the eccentric sleeve at the output end is coaxially matched with the rigid-flexible composite gear through the output end secondary bearing, the eccentric sleeve at the output end is coaxially matched with the fixed large gear through the output end tertiary bearing, and the inner ring of the fixed large gear is matched with the outer ring of the sleeve.

[0007] Optionally, the rigid-flexible composite gear (18) includes an outer gear ring (1804) and an inner gear ring (1805) connected by a metal rubber (1803) and a metal pin (1802); the metal rubber (1803) and the metal pin (1802) are evenly distributed in the inner ring groove of the outer gear ring (1805) along the circumferential direction; the metal rubber (1803) and the metal pin (1802) are fixed in axial position by baffles (1801) at both ends.

[0008] Optionally, the output pinion coincides with the axis of the fixed large gear, the axis of the rigid-flexible composite gear is eccentric to the axis of the output pinion, and the centers of the pitch circles of the inner teeth and the outer teeth of the rigid-flexible composite gear coincide with each other.

[0009] Optionally, the tooth profile end faces of the output pinion, the rigid-flexible composite gear and the fixed large gear are located in the same plane.

[0010] Optionally, primary needle teeth are evenly distributed on the inner circumference of the fixed large gear groove, and the primary needle teeth mesh with the cycloidal external teeth of the rigid-flexible composite gear to form a primary reduction. Secondary needle teeth are evenly distributed on the inner circumference of the inner ring groove of the rigid-flexible composite gear, and the secondary needle teeth mesh with the cycloidal external teeth of the output pinion to form a secondary reduction.

[0011] Optionally, the surface where the eccentric sleeve at the input end cooperates with the secondary bearing at the input end is an eccentric cylindrical surface, and the other cylindrical surfaces are coaxial cylindrical surfaces. The coaxial cylindrical surface is the motion input end, which can drive the eccentric cylindrical surface to rotate and thus drive the rigid-flexible composite gear to rotate.

[0012] Optionally, the surface where the eccentric sleeve at the output end cooperates with the secondary bearing at the output end is an eccentric cylindrical surface, and the other cylindrical surfaces are coaxial cylindrical surfaces. The eccentric cylindrical surface rotates with the revolution of the rigid-flexible composite gear.

[0013] Optionally, the groove of the fixed large gear is an arc groove evenly distributed along the circumference, the primary needle teeth are coaxially matched with the arc groove, the groove of the inner ring of the rigid-flexible composite gear is an arc groove evenly distributed along the circumference, the secondary needle teeth are coaxially matched with the arc groove, and both the primary needle teeth and the secondary needle teeth can roll in the arc groove.

[0014] Optionally, the number of primary pin teeth is z1, the number of epicycloidal teeth of the rigid-flexible composite gear is z2, the number of secondary pin teeth is z3, the number of epicycloidal teeth of the output pinion is z4, z1-z2=1, z3-z4=1, the input eccentric sleeve is the motion input end, the speed is ω1, the output pinion is the motion output end, the speed is ω2, and the reducer transmission ratio is

[0015] Optionally, the grooves on the inner ring of the fixed gear are arc structures evenly distributed around the circumference, and the number of the arc grooves is z1.

[0016] Optionally, the grooves on the inner ring of the rigid-flexible composite gear are arc structures evenly distributed around the circumference, and the number of arc grooves is z3.

[0017] The beneficial effects of the present invention are:

[0018] 1. The first and second stage reduction gears of the present invention are arranged on the same vertical plane, and the axial dimension is significantly shortened;

[0019] 2. The meshing pair of the present invention is a cycloid needle roller meshing pair, and the number of meshing tooth pairs is significantly increased compared with ordinary involute teeth, the load-bearing capacity is large, and the meshing part becomes the rolling friction of the needle roller, which improves the transmission efficiency;

[0020] 3. The present invention has the advantages of simple and compact structure, strong carrying capacity, high power density and stable transmission;

[0021] 4. The present invention introduces a rigid-flexible composite structure to allow the cycloid gear to have a certain degree of flexibility while ensuring accuracy and torque transmission, so as to resist errors caused by processing and manufacturing and increase the stability of transmission.

[0022] 5. The reducer structure of the present invention can be designed in a parameterized and serialized manner and is suitable for a wide range of applications.

[0023] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 It is an isometric diagram of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0026] Figure 2 It is a schematic diagram of the overall half-section structure of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0027] Figure 3 It is a meshing schematic diagram of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the eccentric sleeve at the input end of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0029] Figure 5This is a schematic diagram of the structure of the eccentric sleeve at the output end of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0030] Figure 6 It is a schematic diagram of the rigid-flexible composite gear structure of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0031] Figure 7 It is a schematic diagram of the structure of the output pinion of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention;

[0032] Figure 8 This is a schematic diagram of the fixed large gear structure of the rigid-flexible composite two-stage cycloid planetary reducer of the present invention.

[0033] Figure numerals: 1 output pinion, 2 input end primary bearing, 3 input end eccentric sleeve, 4 input end primary bearing end cover, 5 input end third-stage bearing, 6 input end second-stage bearing end cover, 7 fixed large gear, 8 second-stage pinion, 9 sleeve, 10 output end third-stage bearing, 11 output end second-stage bearing end cover, 12 output end eccentric sleeve, 13 output end primary bearing end cover, 14 output end primary bearing, 15 output end second-stage bearing, 16 first-stage pinion, 17 input end second-stage bearing, 18 rigid-flexible composite gear. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0035] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] See also Figures 1 to 8 , which is a rigid-flexible composite two-stage cycloid planetary reducer, including an output pinion 1, a rigid-flexible composite gear 18, a fixed large gear 7, an input-end eccentric sleeve 3, an output-end eccentric sleeve 12, a primary pinion 16, and a secondary pinion 8. The input-end eccentric sleeve 3 is coaxially matched with the input-end shaft section of the output pinion 1 through the input-end primary bearing 2. The input-end primary bearing 2 is axially fixed through the input-end shaft shoulder of the output pinion 1 and the input-end primary bearing end cover 4. The input-end eccentric sleeve 3 and the input-end primary bearing end cover 4 are fixedly connected by bolts. The input-end eccentric sleeve 3 is coaxially matched with the rigid-flexible composite gear 18 through the secondary bearing 17 at the input end, and the secondary bearing 17 at the input end is axially fixed through the shoulder of the eccentric sleeve 3 at the input end and the shoulder of the rigid-flexible composite gear 18. The eccentric sleeve 3 at the input end is coaxially matched with the fixed large gear 7 through the tertiary bearing 5 at the input end, and the tertiary bearing 5 at the input end is axially fixed through the shoulder of the eccentric sleeve 3 at the input end and the end cover 6 of the secondary bearing at the input end. The fixed large gear 7 and the end cover 6 of the secondary bearing at the input end are fixedly connected by bolts. The eccentric sleeve 12 at the output end is connected to the output small gear through the primary bearing 14 at the output end. The output end shaft section of the gear 1 is coaxially matched, the output end primary bearing 14 is axially fixed through the output end shoulder of the output pinion 1 and the output end primary bearing end cover 13, the output end eccentric sleeve 12 and the output end primary bearing end cover 13 are fixedly connected by bolts, the output end eccentric sleeve 12 is coaxially matched with the rigid-flexible composite gear 18 through the output end secondary bearing 15, the output end secondary bearing 15 is axially fixed through the shoulder of the output end eccentric sleeve 12 and the shoulder of the rigid-flexible composite gear 18, the output end eccentric sleeve 12 is fixed through the output end tertiary bearing 10 The large gear 7 is coaxially matched, and the tertiary bearing 10 at the output end is axially fixed through the shoulder of the eccentric sleeve 12 at the output end and the secondary bearing end cover 11 at the output end. The fixed large gear 7 and the secondary bearing end cover 11 at the output end are fixedly connected by bolts. The inner ring of the fixed large gear 7 and the outer ring of the sleeve 9 are interference fit. The inner circumference of the groove of the fixed large gear 7 is evenly distributed with primary needle teeth 16, which mesh with the cycloidal external teeth of the rigid-flexible composite gear 18. The inner circumference of the inner ring groove of the rigid-flexible composite gear 18 is evenly distributed with secondary needle teeth 8, which mesh with the cycloidal external teeth of the output pinion 1.

[0038] The rigid-flexible composite gear 18 includes a flexible baffle 1801, a metal pin 1802, a metal rubber 1803, an outer gear ring 1804, and an inner gear ring 1805. The outer gear ring 1804 and the inner gear ring 1805 transmit torque by means of the metal pin 1802 and the metal rubber 1803. There is no gap between the metal rubber 1803 and the hole, and there is a gap between the metal pin 1802 and the matching hole. This structure can allow the outer gear ring 1804 to float to a certain extent, and can smoothly bypass the interference points within the meshing cycle to prevent jamming due to processing errors. The metal rubber 1803 can also absorb impact and vibration during the transmission process.

[0039] The eccentric sleeve 3 at the input end includes a first cylindrical surface 301, a second cylindrical surface 302, and a third cylindrical surface 303. The axis of the second cylindrical surface 302 is concentric with the axis of the third cylindrical surface 303. The axis of the first cylindrical surface 301 is eccentric to the axes of the second cylindrical surface 302 and the third cylindrical surface 303. The revolution of the planetary gear is achieved through the eccentricity of the axis of the cylindrical surface 301.

[0040] The eccentric sleeve 12 at the output end includes a first cylindrical surface 1201, a second cylindrical surface 1202, and a third cylindrical surface 1203. The axis of the first cylindrical surface 1201 is eccentric to the axes of the second cylindrical surface 1202 and the third cylindrical surface 1203, and the axis of the second cylindrical surface 1202 is concentric with the axis of the third cylindrical surface 1203. The revolution of the planetary gear is achieved through the eccentricity of the axis of the cylindrical surface 1201, and it is symmetrically arranged with the eccentric sleeve 3 at the input end, thereby improving the stiffness and stability of the reducer.

[0041] The second cylindrical surface 302 of the eccentric sleeve 3 at the input end is coaxially matched with the first shaft section 101 of the output pinion 1 through the first-stage bearing 2 at the input end, and the third cylindrical surface 303 of the eccentric sleeve 3 at the input end is coaxially matched with the first cylindrical surface 701 of the fixed large gear 7 through the third-stage bearing 5 at the input end, thereby ensuring the coaxiality of the output pinion 1 and the fixed large gear 7.

[0042] The fixed large gear 7 is connected to the frame through the outer ring threaded holes to fix the reducer as a whole, the input end eccentric sleeve 3 is connected to the prime mover through the threaded holes evenly distributed on the end surface to realize the input of power, and the output pinion 1 is connected to the output mechanism through the threaded holes evenly distributed on the end surface.

[0043] The eccentric sleeve 3 at the input end transmits the eccentric rotary motion to the rigid-flexible composite gear 18 through the first cylindrical surface. The cycloid outer teeth of the rigid-flexible composite gear 18 mesh with the primary pin teeth 16, so that the rigid-flexible composite gear rotates while revolving, realizing primary reduction. The self-rotation and revolution of the rigid-flexible composite gear are used as input, and the self-rotation of the output pinion gear 1 is realized through the meshing of the cycloid outer teeth and the secondary pin teeth 8, realizing secondary reduction. The initial phase difference of the two-stage reduction meshing is 180°. The cycloid pin teeth meshing pair can significantly improve the overlap and transmission efficiency. The reduction ratio is the reducer transmission ratio is z1 is the number of first-stage pin teeth, z2 is the number of epicycloidal teeth of the rigid-flexible composite gear, z3 is the number of second-stage pin teeth, and z4 is the number of epicycloidal teeth of the output pinion.

[0044] The epicycloid tooth profile parameter equations of the output pinion 1 and the rigid-flexible composite gear 18 are:

[0045]

[0046] in,

[0047] φ is the independent variable, φ∈[0,2π];

[0048] R is the radius of the center distribution circle of the needle teeth;

[0049] r is the radius of the needle teeth;

[0050] e is the eccentricity between the axis of the rigid-flexible composite gear and the axis of the fixed large gear;

[0051] z p is the number of needle teeth;

[0052] z c is the number of teeth of the cycloid gear;

[0053] ΔR is the displacement modification amount;

[0054] Δr is the isometric modification amount;

[0055] θ is the angle modification amount.

[0056] The rigid-flexible composite two-stage cycloid planetary reducer of the present invention is further described below in conjunction with the embodiments:

[0057] A rigid-flexible composite two-stage cycloid planetary reducer is designed for a certain application. The structural diagram of the reducer is as follows: Figure 2As shown, the overall dimensions are, outer diameter φ158mm, total length 79mm; the model of the first-stage bearing 2 at the input end and the first-stage bearing 14 at the output end are both 61816; the model of the second-stage bearing 17 at the input end and the second-stage bearing 15 at the output end are both 61821; the model of the third-stage bearing 5 at the input end and the third-stage bearing 10 at the output end are both 61824. For specific parameters, see Table 1:

[0058] Table 1 Parameters of specific embodiments

[0059]

[0060] The parameters in Table 1 are designed according to certain application scenarios. The numerical values ​​of the parameters are not fixed, and the values ​​of each parameter are not limited to the values ​​in Table 1. Even in the same application scenario, the parameter values ​​in Table 1 can be fine-tuned within the allowable range (i.e., the mechanical properties required to meet the work needs). For example, the equal distance and displacement modification amounts in the table are 0.1 and 0.05 respectively, and the angle modification amount is 0. Using different modification amounts will change the side clearance and thus affect the number of meshing teeth at the same time. In short, under the condition of meeting a specific reduction ratio (not limited to the reduction ratio of -17 in this embodiment), the values ​​of the parameters in Table 1 can be freely set, and the result after free setting is an optimization problem, that is, some solutions have good comprehensive mechanical properties, and some solutions have poor comprehensive mechanical properties.

[0061] The high power density rigid-flexible composite two-stage cycloid planetary reducer of the present invention takes the above-mentioned design case as an example. When in use, the eccentric sleeve 3 at the input end is connected to the prime mover. The eccentric sleeve 3 at the input end is rotated, and the cylindrical surface 301 on it will carry the rigid-flexible composite gear 18 to revolve orbitally. The cycloid outer teeth of the rigid-flexible composite gear 18 are meshed with the primary pin teeth 16, so that the rigid-flexible composite gear rotates while revolving orbitally, thereby realizing primary reduction. The self-rotation and revolution of the rigid-flexible composite gear are used as input, and the self-rotation of the output pinion 1 is realized through the meshing of the cycloid outer teeth of the output pinion 1 and the secondary pin teeth 8, thereby realizing secondary reduction. The total speed ratio satisfies the above-mentioned transmission ratio calculation formula, which is -17 in this design case, where the negative sign represents that the input and output directions are opposite.

[0062] Due to the cycloid needle roller tooth profile of the reducer gear, compared with the involute tooth profile in the existing design, the number of meshing tooth pairs is significantly increased, the overlap is greatly improved, and at the same time, the meshing point becomes rolling friction. Compared with the sliding friction of the involute meshing in the existing design, the efficiency loss caused by friction in the meshing process is greatly reduced, thereby improving the transmission efficiency; the rigid-flexible composite structure adopted in this reducer can make the cycloid gear produce a certain degree of flexibility while ensuring accuracy and transmitting torque, which is used to resist the errors caused by processing and manufacturing. The metal rubber 1803 can also absorb the impact and vibration generated in the transmission process of the cycloid meshing pair, thereby increasing the stability of the transmission; in addition, the primary and secondary transmission of this reducer arranges the fixed large gear 7, the rigid-flexible composite gear 18, and the output small gear 1 on the same plane, so that compared with the traditional small-tooth difference reducer, this reducer has the advantages of compact structure, small axial size, and low overall weight.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A rigid-flexible composite two-stage cycloid planetary reducer, characterized in that: It comprises an output pinion (1), a rigid-flexible composite gear (18), a fixed large gear (7), an input-end eccentric sleeve (3), and an output-end eccentric sleeve (12); The eccentric sleeve (3) at the input end is coaxially matched with the input end shaft section of the output pinion gear (1) through the input end primary bearing (2); the eccentric cylindrical surface of the eccentric sleeve (3) at the input end is coaxially matched with the rigid-flexible composite gear (18) through the input end secondary bearing (17); the eccentric sleeve (3) at the input end is coaxially matched with the fixed large gear (7) through the input end tertiary bearing (5); the eccentric sleeve (12) at the output end is coaxially matched with the output end shaft section of the output pinion gear (1) through the output end primary bearing (14); the eccentric cylindrical surface of the eccentric sleeve (12) at the output end is coaxially matched with the rigid-flexible composite gear (18) through the output end secondary bearing (15); the eccentric sleeve (12) at the output end is coaxially matched with the fixed large gear (7) through the output end tertiary bearing (10); the inner ring of the fixed large gear (7) is matched with the outer ring of the sleeve (9).

2. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The rigid-flexible composite gear (18) comprises an outer gear ring (1804) and an inner gear ring (1805) connected by a metal rubber (1803) and a metal pin (1802); the metal rubber (1803) and the metal pin (1802) are evenly distributed in the inner ring groove of the outer gear ring (1804) along the circumferential direction; the metal rubber (1803) and the metal pin (1802) are fixed in axial position by baffles (1801) at both ends.

3. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The axis of the output pinion (1) coincides with the axis of the fixed large gear (7), the axis of the rigid-flexible composite gear (18) is eccentric to the axis of the output pinion (1), and the centers of the pitch circles of the inner teeth and the outer teeth of the rigid-flexible composite gear (18) coincide.

4. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The tooth profile end faces of the output pinion (1), the rigid-flexible composite gear (18) and the fixed large gear (7) are located in the same plane.

5. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The inner circumference of the groove of the fixed large gear (7) is uniformly distributed with primary pin teeth (16), and the primary pin teeth (16) mesh with the cycloidal external teeth of the rigid-flexible composite gear (18) to form a primary reduction gear. The inner circumference of the inner groove of the rigid-flexible composite gear (18) is uniformly distributed with secondary pin teeth (8), and the secondary pin teeth (8) mesh with the cycloidal external teeth of the output pinion (1) to form a secondary reduction gear.

6. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The surface where the input end eccentric sleeve (3) cooperates with the input end secondary bearing (17) is an eccentric cylindrical surface, and the remaining cylindrical surfaces are coaxial cylindrical surfaces. The coaxial cylindrical surface is the motion input end, driving the eccentric cylindrical surface to rotate, thereby driving the rigid-flexible composite gear (18) to rotate.

7. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 1, characterized in that: The surface where the output end eccentric sleeve (12) and the output end secondary bearing (15) cooperate is an eccentric cylindrical surface, and the remaining cylindrical surfaces are coaxial cylindrical surfaces. The eccentric cylindrical surface rotates with the revolution of the rigid-flexible composite gear (18).

8. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 5, characterized in that: The groove of the fixed large gear (7) is a circular arc groove evenly distributed along the circumference, the first-level needle teeth (16) are coaxially matched with the circular arc groove, the inner ring groove of the rigid-flexible composite gear (18) is a circular arc groove evenly distributed along the circumference, the second-level needle teeth (8) are coaxially matched with the circular arc groove, and both the first-level needle teeth (16) and the second-level needle teeth (8) can roll in the circular arc groove.

9. The rigid-flexible composite two-stage cycloid planetary reducer according to claim 5, characterized in that: The number of the first-stage pin teeth (16) is z1, the number of the outer cycloid teeth of the rigid-flexible composite gear (18) is z2, the number of the second-stage pin teeth (8) is z3, the number of the outer cycloid teeth of the output pinion (1) is z4, z1-z2=1, z3-z4=1, the input eccentric sleeve is the motion input end, the speed is ω1, the output pinion is the motion output end, the speed is ω2, and the speed ratio of the reducer is

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