A compound reduction gear

Abstract

The application provides a composite speed reducer, and relates to the technical field of precision speed reducers.The composite speed reducer comprises a planetary speed reduction structure, a harmonic speed reduction structure and a cross roller bearing, the output end of the planetary speed reduction structure is connected with the input end of the harmonic speed reduction structure, and the planetary speed reduction structure and the harmonic speed reduction structure are connected with the cross roller bearing; the planetary speed reduction structure comprises a fixed flange, a sun gear and a plurality of planetary gears, the sun gear is arranged on the fixed flange and can be connected with the output end of a motor, and the plurality of planetary gears are simultaneously in tooth transmission engagement with the sun gear and the inner ring teeth of the fixed flange. The application has the beneficial effects that: the cross roller bearing is arranged, the outer ring and the inner ring of the cross roller bearing are connected in engagement with a flexspline, the inner ring of the cross roller bearing is connected in differential tooth engagement with the flexspline, the inner ring of the cross roller bearing can replace a traditional rigid gear structure to be used for the output of the harmonic speed reduction structure, and therefore the rigid gear in the traditional harmonic speed reduction structure can be omitted.

Description

Technical Field

[0001] This invention relates to the field of precision speed reducer technology, and more particularly to a composite speed reducer. Background Technology

[0002] As robots and high-end equipment rapidly develop towards higher precision, higher power density, and more compact structures, precision reducers, as core transmission components, directly determine the positioning accuracy, dynamic response, and load capacity of the entire system. To achieve high precision and large reduction ratios, engineering applications primarily employ a reduction structure composed of planetary reducers and harmonic reducers. The output of the planetary reducer structure serves as the input to the harmonic reducer structure; the harmonic reducer, relying on the principle of flexible deformation, comprehensively achieves both high reduction ratios and high-precision transmission, making it suitable for precision scenarios with stringent backlash requirements.

[0003] However, the aforementioned composite reduction structure has significant limitations in terms of small size and ultra-flat design. Specifically, the flexible wheel structure in the harmonic reduction structure results in low load-bearing capacity and overall rigidity, as well as poor impact resistance. Therefore, a rigid wheel is required to ensure the effective integration of the harmonic reduction structure and the planetary reduction structure in the composite structure. However, the rigid wheel structure is external and connected to the harmonic reduction structure via fasteners and cross roller bearings, making it difficult to reduce the axial dimension of the composite reduction structure. This leads to the problem that the existing composite reducer structure generally has a large axial dimension, which has gradually become a bottleneck restricting the development of the entire system towards ultra-flatness and integration. In practical applications, composite reducers often require low back drive, meaning that the output drive of the reverse-drive composite reducer is relatively low. Since the flexible wheel and rigid wheel in the existing harmonic reduction structure are harmonic drives, when the tooth thickness of the flexible wheel is large, the composite reducer cannot achieve the low back drive characteristic. However, the flexible wheel needs to be set with a certain tooth thickness to maintain its stiffness. The solution is to compensate for the overall structural stiffness of the harmonic reduction by increasing the thickness or number of rigid wheels. However, this will further increase the size of the composite reducer. Therefore, due to the influence of the stiffness of the flexible wheel, its tooth thickness has become a bottleneck restricting the composite reducer in the direction of small size and ultra-flat design.

[0004] Therefore, there is an urgent need in this field for a composite reducer structure with an ultra-flat orientation design to overcome the technical limitations of existing composite reducers with large axial dimensions. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a composite reducer to solve the technical problem that the flexible wheel of the harmonic reduction structure in existing composite reducers is difficult to have both stiffness and low tooth thickness, resulting in a large axial dimension of the composite reducer due to the setting of the rigid wheel.

[0006] An embodiment of the present invention provides a composite speed reducer, comprising: Planetary deceleration structure and harmonic deceleration structure; The planetary reduction structure includes a fixed flange, a sun gear, and multiple planet gears. A cylindrical groove is provided on one side of the fixed flange, and a gear ring is provided on the inner wall of the groove. The sun gear is rotatably mounted at the center of the groove. Multiple planet gears simultaneously engage with the sun gear and the gear ring. Each planet gear axis is connected to a shaft pin through a needle roller bearing. The harmonic deceleration structure includes a flexible wheel, a flexible bearing, a wave generator, an output flange, and a crossed roller bearing. The wave generator is driven to mesh with the flexible wheel through the flexible bearing, and all the shaft pins are inserted into the wave generator. The crossed roller bearing includes an inner ring and an outer ring, which are rotatably connected. The outer ring is fixedly connected to the fixed flange, and the inner ring is fixedly connected to the output flange. The inner walls of both the outer ring and the inner ring are provided with internal teeth. The external teeth of the flexible wheel mesh with the internal teeth of the outer ring at equal tooth levels, and the flexible wheel meshes with the internal teeth of the inner ring at differential tooth levels.

[0007] Furthermore, the needle roller bearing is nested at the axis of the planetary gear, the pin is interference-fitted with the inner ring of the needle roller bearing, and the inner roller of the needle roller bearing is tactilely connected to the inner hole of the planetary gear axis.

[0008] Furthermore, the outer ring serves as the first rigid wheel, and the number of its internal teeth is the same as the number of external teeth of the flexible wheel.

[0009] Furthermore, the inner ring serves as the second rigid wheel, and the number of its internal teeth differs from the number of external teeth of the flexible wheel, with the preferred difference being 2 teeth.

[0010] Furthermore, a first gasket is provided between each planetary gear and the fixed flange; a second gasket is provided between the sun gear and the fixed flange; and a third gasket is provided between the sun gear and the wave generator.

[0011] Furthermore, a flexible wheel pressure plate is provided on the side of the wave generator away from the sun gear, and the outer diameter of the flexible wheel pressure plate is larger than that of the wave generator and abuts against the flexible bearing on the outer periphery of the wave generator.

[0012] Furthermore, the output flange and the inner ring are fixed together by a first fixing member; the fixed flange and the outer ring are fixed together by a second fixing member; and the flexible wheel pressure plate and the wave generator are fixed together by a third fixing member.

[0013] Furthermore, the sun gear has a pre-set through hole at its shaft center, and the inner wall of the through hole is provided with a keycap structure for connecting to the input motor shaft.

[0014] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: The composite reducer of the present invention, by setting a crossed roller bearing and meshing both the outer ring and the inner ring of the crossed roller bearing with a flexure, and by setting the inner ring of the crossed roller bearing to mesh with the flexure with differential teeth, allows the inner ring of the crossed roller bearing to replace the traditional rigid wheel structure for the output of the harmonic reduction structure, thus eliminating the rigid wheel in the traditional harmonic reduction structure; at the same time, because the outer ring of the crossed roller bearing also meshes with the flexure, and both have the same number of teeth, when the flexure deforms during harmonic transmission, the outer ring of the bearing will not rotate, and the inner ring is rotatably connected relative to the outer ring, thus fixing the outer ring. By fixing the flange, the outer ring can serve as an additional rigid wheel structure to reinforce the overall rigidity of the harmonic reduction structure. Therefore, the tooth thickness of the flexible wheel can be reduced compared to the traditional flexible wheel tooth thickness. Since the cross roller bearing is an inherent component in the harmonic reduction structure, it will not increase the axial dimension of the composite reducer. By reducing the tooth thickness of the flexible wheel, the meshing clearance between the outer teeth of the flexible wheel and the inner teeth of the cross roller inner ring, which serves as the rigid wheel structure, can be increased. This can significantly improve the phenomenon of large back drive in the reducer, allowing the composite reducer to simultaneously achieve the technical effects of reducing the axial dimension of the composite reducer by eliminating the rigid-flexible structure and reducing the back drive of the composite reducer by reducing the tooth thickness of the flexible wheel. The composite reducer of the present invention, by setting a shaft pin connecting the planetary gear and the wave generator to be connected to the planetary gear through a needle roller bearing, transforms the original sliding friction transmitted from the planetary reduction structure to the harmonic reduction structure into rolling friction, thereby reducing the reverse drive resistance and further reducing the reverse drive force of the composite reducer. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the longitudinal cross-sectional structure of the composite reducer of the present invention; Figure 2 This is a schematic diagram of the needle roller bearing connecting the planetary gear portion of the composite reducer of the present invention; Figure 3 This is a schematic diagram of the harmonic deceleration section and the crossed roller bearing section of the composite reducer of the present invention. Figure 4 This is a diagram showing the meshing state of the flexible wheel and rigid wheel in an embodiment of the composite reducer of the present invention; Figure 5 This is a diagram showing the meshing state of the flexspline and inner ring of the composite reducer of the present invention; Figure 6 This is a schematic diagram of the standard rigid wheel tooth structure in an embodiment of the composite reducer of the present invention; Figure 7 This is a schematic diagram of the inner ring tooth structure of the composite reducer of the present invention.

[0016] In the diagram: 1. Fixed flange; 2-1. First gasket; 2-2. Second gasket; 2-3. Third gasket; 3. Needle roller bearing; 4. Planetary gear; 5. Shaft pin; 6. Sun gear; 7. Flexible gear; 8. Flexible gear pressure plate; 9. Output flange; 10-1. First fixing component; 10-2. Second fixing component; 10-3. Third fixing component; 11-1. Inner ring; 11-2. Outer ring; 12. Wave generator; 13. Flexible bearing. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The following description presents a preferred embodiment of the various possible embodiments of the present invention, intended to provide a basic understanding of the invention, but not intended to identify key or decisive elements of the invention or to limit the scope of protection sought.

[0018] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0019] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures. Also, it should be understood that, for ease of description, the dimensions of the various parts shown in the figures are not drawn to actual scale.

[0021] In the description of this invention, it should be noted that the circuits, electronic components and modules involved in this invention are all prior art, which can be fully implemented by those skilled in the art, and need not be elaborated upon. The content protected by this invention does not involve improvements to the internal structure and method.

[0022] It should be further noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Please refer to Figure 1 The present invention provides a composite speed reducer, including a planetary speed reduction structure and a harmonic speed reduction structure.

[0024] The planetary reduction structure includes a fixed flange 1, a sun gear 6, multiple planet gears 4, and a shaft pin 5; the harmonic reduction structure includes a wave generator 12, a flexible bearing 13, a flexible wheel 7, a crossed roller bearing, and an output flange 9.

[0025] The fixed flange 1 serves as the support base for the entire machine and can be fixedly connected to the external frame through circumferentially distributed bolt holes. The wave generator 12 in the harmonic deceleration structure is rotatably mounted on one side of the fixed flange 1. The fixed flange 1 has a cylindrical groove on the axial center of the side of the wave generator 12. This groove is used to provide installation space for the sun gear 6 and multiple planet gears 4. At the same time, the fixed flange 1 has a through hole in the center of the groove so that the external input source (motor shaft) can be inserted into the groove and connected to the shaft of the sun gear 6.

[0026] Furthermore, the sun gear 6 is rotatably disposed in the groove of the fixed flange 1 and located between the wave generator 12 and the groove wall, and the axis of the sun gear 6 is coaxially disposed with the central through hole of the fixed flange 1, so that the sun gear 6 can rotate freely around the central axis of the fixed flange 1.

[0027] Preferably, the inner wall of the sun gear 6 is provided with a keyway structure (such as a flat keyway or spline) for forming a key connection with the output shaft of an external motor to receive input torque and transmit rotational motion.

[0028] Preferably, a second gasket 2-2 is provided between the sun gear 6 and the axial end face of the fixed flange 1. The thickness of the second gasket 2-2 is adjusted according to the assembly clearance, and is usually controlled within the range of 0.01 mm to 0.05 mm, in order to avoid axial movement during operation, thereby reducing end face friction and wear and improving transmission accuracy.

[0029] It should be noted that internal teeth are machined on the inner wall of the groove of the fixed flange 1 to form an internal gear ring. Multiple planet gears 4 (preferably 3) are evenly distributed along the circumference of the sun gear 6. The external teeth of each planet gear 4 simultaneously form an external meshing pair with the external teeth of the sun gear 6 and an internal meshing pair with the internal gear ring of the gear ring flange, thereby forming a complete planetary reduction transmission chain and realizing the first stage of reduction and torque increase.

[0030] Each planetary gear 4 has a needle roller bearing 3 nested inside its central hole, and each planetary gear 4 is connected to a pin 5 through the needle roller bearing 3 in its central hole. Specifically, the rollers of the needle roller bearing 3 are in rolling contact with the central hole of the planetary gear 4, and the inner ring of the needle roller bearing 3 is in an interference fit with the pin 5. The planetary gear 4 can rotate flexibly relative to the pin 5, while the needle roller bearing 3 effectively reduces friction, thereby reducing the reverse driving force.

[0031] Furthermore, the wave generator 12 has a pin hole on one side facing the fixed flange 1, and one end of the shaft pin 5 is connected to the pin hole of the wave generator 12. This connection method converts the revolution and rotation of the planetary gear 4 into the eccentric rotation input of the wave generator 12, that is, the output of the planetary gear 4 directly drives the wave generator 12 to generate periodic elliptical deformation motion.

[0032] Therefore, pin 5 forms the output end of the planetary reduction gear structure. This structure eliminates the traditional planetary carrier and intermediate connecting components, allowing the first-stage reduction output to be directly coupled with the second-stage reduction input, effectively shortening the transmission chain length and reducing the axial dimension.

[0033] Please see Figure 1 and Figure 2 A first gasket 2-1 is provided between the axial end face of each planetary gear 4 and the fixed flange 1. The first gasket 2-1 is used to adjust the axial position of the planetary gear 4, ensuring the meshing accuracy between the planetary gear 4, the sun gear 6, and the gear ring flange, while reducing end face friction. A third gasket 2-3 is provided between the sun gear 6 and the wave generator 12, used to isolate the sun gear 6 and the wave generator 12 and control their axial clearance to prevent operational interference.

[0034] It should be noted that the wave generator 12 has an elliptical cam structure, and its geometric center has a predetermined eccentricity relative to the central axis of the whole machine. The wave generator 12 receives the output motion of the planetary reduction structure through the aforementioned shaft pin 5. Driven by the shaft pin 5, the geometric center of the wave generator 12 rotates eccentrically around the central axis of the whole machine. At the same time, the wave generator 12 itself rotates around its geometric center at the input speed, forming an eccentric rotation input, which directly drives the subsequent harmonic transmission.

[0035] Furthermore, the flexible bearing 13 is mounted on the outer periphery of the wave generator 12, the inner ring of the flexible bearing 13 is tightly fitted with the outer periphery of the wave generator 12, and the outer ring of the flexible bearing 13 is tightly fitted with the cylindrical inner wall of the flexible wheel 7.

[0036] When the wave generator 12 rotates eccentrically, the flexible bearing 13 forces the flexible wheel 7 to undergo periodic radial elastic deformation, making the flexible wheel 7 elliptical.

[0037] Please refer to Figure 1 and Figure 3 The crossed roller bearing includes an outer ring 11-2 and an inner ring 11-1. The inner and outer rings are rotatably connected by crossed rollers, and can simultaneously withstand radial loads, axial loads, and overturning moments, thus providing both precision support and torque transmission. The outer ring 11-2 is fixedly connected to the fixed flange 1 by a second fastener 10-2 (such as a high-strength bolt or spline), forming a rigid fixed support.

[0038] The inner wall of the outer ring 11-2 is machined with internal teeth, the number of which is the same as the number of teeth of the outer teeth of the flexible wheel 7, and it meshes tightly with the outer teeth of the long shaft area of ​​the deformed flexible wheel 7. Since the two have the same number of teeth and no relative rotation during operation, the outer ring 11-2, as the first rigid wheel, provides radial auxiliary support for the flexible wheel 7 and significantly enhances the overall structural rigidity.

[0039] Furthermore, the inner ring 11-1 is fixedly connected to the output flange 9 via a first fastener 10-1 (such as a high-strength bolt). The inner wall of the inner ring 11-1 is machined with internal teeth, the number of which differs from the number of external teeth of the flexible wheel 7 (preferably 2 teeth), forming a differential tooth meshing transmission with the flexible wheel 7. The elliptical deformation of the flexible wheel 7 causes the teeth in its major axis region to mesh with the internal teeth of the inner ring 11-1. As the wave generator 12 rotates, the meshing area moves continuously circumferentially, achieving a second-stage deceleration using the tooth difference, transmitting motion and torque to the inner ring 11-1, thereby driving the output flange 9 to rotate. The output flange 9, as the final output end, transmits the decelerated torque to the load end.

[0040] Please refer to Figure 4 , Figure 4 The diagram shows the meshing state of the rigid wheel and the flexible wheel under standard conditions. The distance between the inner diameter of the flexible wheel 7 and its tooth tip is defined as M, where M represents the chordal tooth thickness of the flexible wheel 7 (the value of M is related to many factors such as the reducer model, speed ratio, and application, and there is no uniform value). Under this standard condition, the rigid wheel and the flexible wheel mesh. Considering the torsional stiffness and transmitted torque of the reducer, the larger the torsional torque, the larger the value of M for the flexible wheel. However, increasing the value of M will lead to a larger back drive of the reducer. Usually, the value of M needs to be balanced between stiffness and appropriate back drive.

[0041] Refer again Figure 5 , Figure 5 This is a diagram showing the meshing state of the flexible wheel 7 and the inner ring 11-1 in this embodiment. Since the inner ring 11-1 and the outer ring 11-2 of the crossed roller bearings serve as double rigid wheels to compensate for the overall stiffness of the harmonic reduction structure, the harmonic reduction structure can obtain sufficient torsional stiffness and transmit torque. Therefore, the value of M can be reduced to less than the value under standard conditions. This makes the tooth tip of the flexible wheel 7 and the tooth root clearance of the inner tooth of the inner ring 11-1 larger, thereby reducing the reverse drive of the reducer.

[0042] Preferably, a flexible wheel pressure plate 8 is provided on the side of the wave generator 12 away from the sun gear 6. The flexible wheel pressure plate 8 is fixedly connected to the end face of the wave generator 12 by a third fixing member 10-3 (such as a countersunk screw). The outer diameter of the flexible wheel pressure plate 8 is larger than the outer diameter of the wave generator 12, and its outer peripheral end face abuts against the end face of the flexible bearing 13 on the outer periphery of the wave generator 12, thereby axially limiting the flexible bearing 13 and preventing axial movement of the flexible bearing 13 under high-speed rotation or load impact, thereby improving the reliability of the system.

[0043] In this embodiment, the torque transmission path is as follows: motor output shaft → sun gear 6 → planetary gear 4 (first-stage reduction) → shaft pin 5 → wave generator 12 → flexible bearing 13 → deformation of flexible wheel 7 → differential gear meshing between flexible wheel 7 and inner ring 11-1 (second-stage reduction) → inner ring 11-1 → output flange 9.

[0044] This embodiment directly drives the wave generator 12 via the shaft pin 5, eliminating the traditional independent planetary carrier and intermediate connection structure, thus achieving tight coupling of the two-stage reduction. Simultaneously, the inner and outer rings of the crossed roller bearing integrate the functions of the first rigid wheel (support) and the second rigid wheel (transmission), respectively, and directly connect the fixed flange 1 and the output flange 9, significantly reducing the number of parts, substantially compressing the axial dimension, and achieving an ultra-flat structure. Furthermore, because the inner and outer rings of the crossed roller bearing integrate the functions of the first rigid wheel (support) and the second rigid wheel (transmission), the tooth thickness M value of the flexible wheel 7 can be reduced, thereby increasing the clearance between the outer teeth of the flexible wheel 7 and the inner teeth of the inner ring of the crossed roller bearing, achieving a low back-drive characteristic. Through the low-friction support of the needle roller bearing 3, the low back-drive characteristic is ultimately achieved.

[0045] Optimization of eccentric parameters for pin 5 It should be further explained that in the first-stage planetary reduction system, the shaft pin 5 is designed as an eccentric pin structure with a predetermined eccentricity. The eccentricity is designed to match the module, tooth profile parameters of the flexure 7 and the deformation required by the wave generator 12, so that the radius of the revolution trajectory of the shaft pin 5 around the central axis of the whole machine is consistent with the eccentricity required by the wave generator 12. This directly converts the revolution motion of the planetary gear 4 into the stable eccentric rotation of the wave generator 12, improves the deformation consistency of the flexure 7, ensures the continuous circumferential distribution of the meshing area, and avoids local stress concentration.

[0046] Harmonic deceleration structure and size optimization Furthermore, in the two-stage harmonic reduction system, both the inner and outer rings of the crossed roller bearing are equipped with internal gear structures. The inner ring 11-1 serves as the second rigid wheel, forming a differential gear meshing transmission with the flexure 7 to achieve reduction output. The outer ring 11-2 serves as the first rigid wheel, with the same number of internal teeth as the external teeth of the flexure 7. During operation, it closely meshes with the long axis region of the flexure 7 without generating relative movement, thus providing auxiliary support and enhancing rigidity. The output flange 9 is directly fixedly connected to the inner ring 11-1 of the crossed roller bearing via the first fixing member 10-1, minimizing the torque output path, reducing error accumulation and torsional clearance caused by intermediate connecting parts, and improving transmission accuracy.

[0047] In terms of structural dimension design, proportional matching design is carried out for the tooth width of the flexible wheel 7, the widths of the inner and outer rings of the cross roller bearing, and the width of the flexible bearing 13, with a preferred proportional range of 1:0.8:0.85, so as to achieve a compact structure while ensuring the load-bearing capacity, meshing contact ratio and bearing life. In addition, by optimizing the tooth width distribution and tooth profile modification along the tooth direction, the unit contact stress can be reduced, the load distribution can be improved, and the tooth surface life and transmission stability can be enhanced.

[0048] Improvement of the tooth profile of the inner ring of the cross roller bearing serving as the second rigid gear Please refer to Figure 6 and Figure 7 , Figure 6 is a schematic diagram of the rigid gear tooth profile structure under standard conditions, where H1 is defined as the tooth height, and R1 is defined as the tooth root fillet (the fillet here is not a single arc, but refers to the overall radian at the tooth root), Figure 7 is a schematic diagram of the tooth profile structure of the inner ring 11-1 of the cross roller bearing in this embodiment, where H2 is defined as the tooth height, and R2 is defined as the tooth root fillet.

[0049] Specifically, in this embodiment, the tooth height H value is reduced, but the tooth root fillet R is increased, so that most of the contact positions between the flexible gear and the rigid gear are located in the disengagement meshing zone.

[0050] Preferred values: 0.34R1<R2<0.65R1, 0.5H1<H2<H1.

[0051] In this document, the directional terms such as front, rear, upper and lower involved are defined based on the positions of components in the accompanying drawings and the mutual positions between the components, and are only used for the clarity and convenience of expressing the technical solutions. It should be understood that they are relative concepts that can change correspondingly according to different modes of use and placement, and the use of directional terms should not limit the scope of protection claimed in the present application.

[0052] In the case of no conflict, the above-mentioned embodiments and the features in the embodiments in this document can be combined with each other.

[0053] The above description is only the preferred embodiments of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall all be included in the protection scope of the present invention.

Claims

1. A composite reducer, characterized in that, include: Planetary deceleration structure and harmonic deceleration structure; The planetary reduction structure includes a fixed flange (1), a sun gear (6) and multiple planet gears (4). A cylindrical groove is provided on one side of the fixed flange (1), and a gear ring is provided on the inner wall of the groove. The sun gear (6) is rotatably mounted at the center of the groove. Multiple planet gears (4) simultaneously engage with the sun gear (6) and the gear ring. The center of each planet gear (4) is connected to a pin (5) through a needle roller bearing (3). The harmonic deceleration structure includes a flexible wheel (7), a flexible bearing (13), a wave generator (12), an output flange (9), and a cross roller bearing. The wave generator (12) is driven to mesh with the flexible wheel (7) through the flexible bearing (13), and all the shaft pins (5) are inserted into the wave generator (12). The crossed roller bearing includes an inner ring (11-1) and an outer ring (11-2). The inner ring (11-1) and the outer ring (11-2) are rotatably connected. The outer ring (11-2) is fixedly connected to the fixed flange (1). The inner ring (11-1) is fixedly connected to the output flange (9). The inner walls of the outer ring (11-2) and the inner ring (11-1) are provided with internal teeth. The external teeth of the flexible wheel (7) mesh with the internal teeth of the outer ring (11-2) with equal teeth. The flexible wheel (7) meshes with the internal teeth of the inner ring (11-1) with differential teeth.

2. The composite reducer as described in claim 1, characterized in that: The needle roller bearing (3) is nested at the axis of the planetary gear (4), the pin (5) is interference-fitted with the inner ring of the needle roller bearing (3), and the inner roller of the needle roller bearing (3) is tumbling connected to the inner hole of the axis of the planetary gear (4).

3. The composite reducer as described in claim 1, characterized in that: The outer ring (11-2) serves as the first rigid wheel, and the number of its internal teeth is the same as the number of external teeth of the flexible wheel (7).

4. The composite reducer as described in claim 1, characterized in that: The inner ring (11-1) serves as the second rigid wheel, and the number of its internal teeth differs from the number of external teeth of the flexible wheel (7). The preferred difference in the number of teeth is 2 teeth.

5. The composite reducer as described in claim 1, characterized in that: A first gasket (2-1) is provided between each of the planetary gears (4) and the fixed flange (1); a second gasket (2-2) is provided between the sun gear (6) and the fixed flange (1); and a third gasket (2-3) is provided between the sun gear (6) and the wave generator (12).

6. The composite reducer as described in claim 1, characterized in that: The wave generator (12) has a flexible wheel pressure plate (8) on one side away from the sun gear (6). The outer diameter of the flexible wheel pressure plate (8) is larger than that of the wave generator (12) and abuts against the flexible bearing (13) on the outer periphery of the wave generator (12).

7. The composite reducer as described in claim 6, characterized in that: The output flange (9) and the inner ring (11-1) are fixed together by a first fastener (10-1); the fixed flange (1) and the outer ring (11-2) are fixed together by a second fastener (10-2); the flexible wheel pressure plate (8) and the wave generator (12) are fixed together by a third fastener (10-3).

8. The composite reducer as described in claim 1, characterized in that: The sun gear (6) has a pre-set through hole at its shaft center, and the inner wall of the through hole is provided with a keycap structure for connecting with the input motor shaft.

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