Two-stage planetary gear reducer of joint motor

Abstract

The utility model discloses a two-stage planetary gear reducer of a joint motor, which comprises a first-stage gear set, a second-stage gear set, a third-stage gear set, a fourth-stage gear set and a fifth-stage gear set, the second-stage gear set comprises a second-stage sun gear and a plurality of second-stage planet gears which are meshed with each other; the hollow shaft comprises an output shaft and a transmission shaft which wrap the first-stage gear set and the second-stage gear set respectively, and the hollow shaft comprises a radial hollow window for exposing the first-stage planet gear or the second-stage planet gear; the inner wall of the inner gear ring comprises an inner tooth part meshed with the first-stage planet wheel and the second-stage planet wheel; wherein the first-stage gear set and the second-stage gear set are coaxially arranged in the axial direction, and the inner gear ring is coaxially arranged outside the hollow shaft. According to the two-stage planetary gear mechanism, through axial coaxial arrangement of the two-stage gear sets, two-stage speed reduction is achieved in a limited space, the transmission ratio is remarkably increased, compact integration of a two-stage speed reduction structure is achieved, and then a joint motor adopting the two-stage planetary gear mechanism also meets the requirement for the compact structure.

Description

Technical Field

[0001] This utility model relates to the field of planetary gears, specifically to a two-stage planetary gear reducer for a joint motor. Background Technology

[0002] With the continuous upgrading and development of industry, robots are being used more and more widely in the industrial field and many other fields, and the performance requirements for robots are also increasing. Traditional robots use separate components such as servo motors and harmonic reducers, but they have problems such as bulky bodies, complex wiring, and non-compact structures, making it difficult to meet the needs of robots to develop towards lightweight, miniaturized, high-precision, and highly flexible designs.

[0003] Currently, most mainstream servo integrated joints use the joint housing as the outer part. This requires coordinating the size of harmonics and motors, as well as taking into account the mounting position of the circumferential screws at the output end. While the integration level is high, the structure of the housing is complex and difficult to manufacture, resulting in a larger joint motor size and poor reusability.

[0004] The miniaturization demand for joint motors in quadruped and humanoid robots is increasingly significant, requiring compact joints to integrate drive, transmission, and sensing functions within a limited space. However, existing harmonic reducer designs present the following contradictions: On the one hand, to achieve high torque output and transmission accuracy, multi-stage gear meshing or an increase in the number of teeth on the flexspline is necessary, leading to an increase in the axial length or radial dimension of the reducer; on the other hand, while the tooth profile design of traditional rigid and flexspline wheels (such as involute teeth) can ensure meshing smoothness, limitations in machining accuracy and assembly tolerances make it difficult to simultaneously meet strength and miniaturization requirements in thin-walled flexspline structures. Furthermore, the thermal expansion effect and lubrication space occupied within the reducer further limit its potential for volume reduction.

[0005] Planetary gear systems play a crucial role in the core transmission mechanism of robot joint motors. Through multi-stage gear meshing, they achieve efficient power transmission and precise speed reduction, making them a key technology for improving joint performance. A typical planetary gear system consists of a sun gear, planet gears, an internal ring gear, and a planet carrier. The principle is that power is input through the sun gear, driving the planet gears to revolve around the sun gear and rotate on their own axes, while simultaneously meshing with the internal ring gear. Finally, the planet carrier outputs high-torque after speed reduction. This structure can convert the high-speed, low-torque output of the motor into low-speed, high-torque output, meeting the demands of robot joints for precise movement and high load capacity.

[0006] Planetary gears are widely used in the field of robot joint motors. The demand for miniaturization and compactness of robot joint motors has also put forward design requirements for smaller, more compact, and more reliable force transmission of the planetary gears inside the robot joint motors. Utility Model Content

[0007] The problem to be solved by this utility model is to provide a two-stage planetary gear reducer for articulated motors. By arranging the two-stage gear sets axially and coaxially, two-stage reduction is achieved in a limited space, which significantly improves the transmission ratio and realizes the compact integration of the two-stage reduction structure. As a result, articulated motors using this two-stage planetary gear mechanism also meet the requirements of compact structure.

[0008] To solve the above problems, this utility model provides a two-stage planetary gear reducer for a joint motor. To achieve the above objectives, the technical solution adopted by this utility model to solve its technical problems is as follows:

[0009] A two-stage planetary gear reducer for a joint motor includes: a first-stage gear set, including a first-stage sun gear and several first-stage planet gears meshing with each other; a second-stage gear set, including a second-stage sun gear and several second-stage planet gears meshing with each other; a hollow shaft, including an output shaft and a transmission shaft respectively enclosing the first-stage gear set and the second-stage gear set, the hollow shaft including radially hollowed-out windows for exposing the first-stage or second-stage planet gears; and an internal gear ring, the inner wall of which includes internal teeth that mesh with the first-stage and second-stage planet gears; wherein the first-stage gear set and the second-stage gear set are arranged coaxially along the axial direction, and the internal gear ring is arranged coaxially outside the hollow shaft.

[0010] As a further improvement of this utility model, the first-stage sun gear includes a first gear tooth segment, and the first-stage sun gear has a first optical axis segment at both ends of the first gear tooth segment. The second-stage sun gear includes a second gear tooth segment, and the second-stage sun gear has a second optical axis segment at the end of the second gear tooth segment opposite to the first-stage sun gear. The first gear tooth segment meshes with the first-stage planetary gear, and the second gear tooth segment meshes with the second-stage planetary gear.

[0011] As a further improvement of this utility model, the shaft length of the first gear segment is greater than the shaft length of the second gear segment; the number of first-stage or second-stage planetary gears ranges from three to six.

[0012] As a further improvement of this utility model, a first bearing is fitted on a first optical shaft segment away from the second optical shaft segment, and a second bearing is fitted on a second optical shaft segment; a first bolt group is assembled at the end of the second sun gear away from the first gear set.

[0013] As a further improvement of this utility model, each radially perforated window allows a first-stage planetary gear or a second-stage planetary gear to pass through, and the circumferential width of the radially perforated window is smaller than the diameter of the first-stage or second-stage planetary gear.

[0014] As a further improvement of this utility model, the diameter of the first bearing is smaller than that of the second bearing, and the outer rings of the first bearing and the second bearing are respectively assembled with the inner walls of the output shaft and the transmission shaft; the inner wall of the radially hollowed-out window is connected to the first-stage planetary gear or the second-stage planetary gear.

[0015] As a further improvement of this utility model, the diameters of the first-stage sun gear and the second-stage sun gear are equal, and the diameters of the first-stage planet gear and the second-stage planet gear are equal.

[0016] As a further improvement of this utility model, the shaft length of the internal gear ring is not less than the sum of the shaft lengths of the first-stage gear set and the second-stage gear set, and the shaft length of the output shaft is greater than the shaft length of the transmission shaft.

[0017] As a further improvement of this utility model, the outer wall of the internal gear ring has a first outwardly extending flange portion at one end near the first-stage gear set.

[0018] As a further improvement of this utility model, a first retaining ring is assembled together with the outer wall of the output shaft at one end of the internal gear ring, and a second retaining ring is assembled together with the outer wall of the transmission shaft at the inner wall of the internal gear ring.

[0019] The beneficial effects of the two-stage planetary gear reducer for the articulated motor in this application include:

[0020] First, by axially coaxially arranging the first-stage gear set and the second-stage gear set, two-stage reduction is achieved within a limited space, significantly improving the transmission ratio, realizing the compact integration of the two-stage reduction structure, significantly reducing the radial space occupied by the reducer, and meeting the miniaturization requirements of the joint motor.

[0021] Secondly, the hollow shaft employs a split-type output shaft and transmission shaft to enclose a two-stage gear set, combined with a radially perforated window design. This design ensures gear meshing accuracy while reducing overall rotational inertia, forming a lightweight support frame. Weight reduction is achieved while maintaining structural strength, and the perforated windows allow the planetary gears to be partially exposed, which is beneficial for heat dissipation and lubrication.

[0022] Furthermore, the integrated design of synchronous meshing between the inner wall of the internal gear ring and the two-stage planetary gears optimizes the load distribution path, disperses the load through multi-tooth contact, reduces energy loss in the transmission chain, and improves torque transmission efficiency.

[0023] Finally, the coaxial nesting layout of the two-stage gear set with the hollow shaft and internal gear ring forms a modular assembly benchmark, which simplifies the manufacturing process, enhances structural rigidity, and ensures dynamic stability under high-speed operation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a perspective view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model;

[0026] Figure 2 This is a perspective view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model;

[0027] Figure 3 This is a front view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model.

[0028] Figure 4 This is a cross-sectional view (AA) of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model.

[0029] Figure 5 This is an exploded view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model;

[0030] Figure 6 This is an exploded view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model;

[0031] Figure 7 This is an exploded view of one embodiment of the two-stage planetary gear reducer for the joint motor of this utility model;

[0032] Figure 8 This is a perspective view of one implementation of an axially compressed integrated robot joint motor;

[0033] Figure 9 This is a perspective view of one implementation of an axially compressed integrated robot joint motor;

[0034] Figure 10 This is a front view of one implementation of an axially compressed integrated robot joint motor;

[0035] Figure 11 This is a BB cross-sectional view of one embodiment of an axially compressed integrated robot joint motor;

[0036] Figure 12 This is an exploded view of one implementation of an axially compressed integrated robot joint motor.

[0037] Figure 13 This is an exploded view of one implementation of an axially compressed integrated robot joint motor.

[0038] 1-Internal gear ring; 101-Internal gear section; 102-First tubular section; 103-First outer flange section; 104-First circumferential groove; 2-Output shaft; 201-First radial perforated window; 3-Drive shaft; 301-Second radial perforated window; 4-First-stage planetary gear; 5-Second-stage planetary gear; 6-First-stage sun gear; 601-First gear segment; 602-First optical shaft segment; 7-Second-stage sun gear; 701-Second gear segment; 702-Second optical shaft segment; 8-First bolt group; 9-First bearing; 10-Second bearing; 11-First retaining ring; 12-Second retaining ring; 30-Output flange; 31-Output end cover; 32-Input housing; 3201-Second tubular section; 3202-Second inner flange section; 33-Drive housing flange; 3301-Side opening; 34-Drive plate; 3401-Electrical component; 35-Rotor; 3501-End plate section; 3502-Third tubular section; 3503-Magnet; 3504-Axial hollow hole; 36-Stator; 3601-Iron core; 37-Rear end cover; 38-Outgoing wire partition; 39-Second bolt group; 40-Third bolt group. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments:

[0040] To achieve the purpose of this utility model, please refer to Figures 1 to 7 A two-stage planetary gear reducer for a joint motor includes: a first-stage gear set, comprising a first-stage sun gear 6 and several first-stage planetary gears 4 meshing with each other; a second-stage gear set, comprising a second-stage sun gear 7 and several second-stage planetary gears 5 meshing with each other; a hollow shaft, comprising an output shaft 2 and a transmission shaft 3 respectively enclosing the first-stage and second-stage gear sets, the hollow shaft including radially perforated windows for exposing the first-stage or second-stage planetary gears 4 and 5; and an internal gear ring 1, the inner wall of which includes internal gear portions 101 meshing with the first-stage and second-stage planetary gears 4 and 5. The first-stage and second-stage gear sets are coaxially arranged along the axial direction, and the internal gear ring 1 is coaxially arranged outside the hollow shaft.

[0041] The beneficial effects of adopting the above technical solution are as follows: By coaxially arranging a two-stage planetary gear set and engaging with the internal gear ring 1, a compact axial layout of the power transmission path is achieved, enabling two-stage reduction within a limited space, significantly improving the transmission ratio, and effectively reducing the size of the planetary gear reducer. The hollow shaft's encasing structure, combined with its radially perforated window design, ensures gear meshing accuracy while forming a lightweight support frame, reducing overall rotational inertia and overall volume. The synchronous meshing design of the internal gear ring 1 and the two-stage gear set ensures the torque superposition effect of the two-stage reduction, improving transmission efficiency. When used in robot joints, it meets the requirements for lightweight and compact robot joints.

[0042] In some other embodiments of this utility model, the first-stage sun gear 6 includes a first gear tooth segment 601, and both ends of the first gear tooth segment 601 have first optical axis segments 602. The second-stage sun gear 7 includes a second gear tooth segment 701, and the end of the second gear tooth segment 701 opposite to the first-stage sun gear 6 has a second optical axis segment 702. The first gear tooth segment 601 meshes with the first-stage planetary gear 4, and the second gear tooth segment 701 meshes with the second-stage planetary gear 5.

[0043] The beneficial effects of adopting the above technical solution are: by setting optical shaft sections at both ends of the sun gear, a precise axial positioning reference is provided for the bearing, ensuring the coaxiality and rotational accuracy of the gear set. The combined design of the split gear tooth section and the optical shaft section optimizes the machinability of the sun gear, reduces the manufacturing cost of complex tooth profiles, and also facilitates a simplified assembly process.

[0044] In some other embodiments of this invention, the shaft length of the first gear segment 601 is greater than the shaft length of the second gear segment 701. The number of first-stage planetary gears 4 or second-stage planetary gears 5 ranges from three to six.

[0045] like Figure 7 As shown, the number of first-level planetary gears 4 and second-level planetary gears 5 can each be four, with several first-level planetary gears 4 arranged in a ring array around the first-level sun gear 6, and several second-level planetary gears 5 arranged in a ring array around the second-level sun gear 7.

[0046] The axial length of the first gear segment 601 is equal to the axial length of the teeth of the first-stage planetary gear 4 itself, and the axial length of the second gear segment 701 is equal to the axial length of the teeth of the second-stage planetary gear 5 itself.

[0047] The beneficial effects of adopting the above technical solution are: by differentiating the shaft length of the tooth segments of the two-stage sun gear, the first-stage gear set obtains a larger meshing contact area to improve load-bearing capacity, while the second-stage gear set retains sufficient radial space for bearing arrangement. Furthermore, limiting the number of planetary gears, and thus determining the approximate diameter range of the planetary gears, avoids increased assembly complexity due to an excessive number of planetary gears, while ensuring load-sharing performance.

[0048] In some other embodiments of this utility model, a first bearing 9 is fitted onto a first optical shaft segment 602 facing away from the second-stage gear set, and a second bearing 10 is fitted onto a second optical shaft segment 702. A first bolt group 8 is assembled at the end of the second-stage sun gear 7 facing away from the first-stage gear set.

[0049] The first bolt group 8 actually contains multiple independent bolts that are parallel to each other.

[0050] The beneficial effects of adopting the above technical solution are: by utilizing the bearing support structure on the optical axis section, the radial runout of the sun gear is precisely constrained, reducing vibration and noise during high-speed operation. The secondary sun gear is fixed by a bolt group, enabling controllable adjustment of the axial preload. The first bolt group 8 can be used to fix the sun gear to an external drive device (such as a motor), ensuring the stability and reliability of the power input.

[0051] In some other embodiments of this utility model, a primary planetary gear 4 or a secondary planetary gear 5 passes through each radially perforated window, and the circumferential width of the radially perforated window is smaller than the diameter of the primary planetary gear 4 or the secondary planetary gear 5.

[0052] The radial perforated window includes a first radial perforated window 201 located on the output shaft 2, and a second radial perforated window 301 located on the transmission shaft 3.

[0053] The beneficial effects of adopting the above technical solution are: limiting the circumferential width of the perforated window to be less than the diameter of the planetary gear, reducing weight while ensuring structural strength, achieving lightweighting, and avoiding a decrease in structural strength due to an excessively large window. Through the matching design of a single window and a single planetary gear, a directional lubrication channel is formed, while preventing external impurities from entering the meshing area.

[0054] In some other embodiments of this utility model, the diameter of the first bearing 9 is smaller than the diameter of the second bearing 10, and the outer rings of the first bearing 9 and the second bearing 10 are respectively assembled with the inner walls of the output shaft 2 and the transmission shaft 3. The inner wall of the radially hollowed-out window is axially connected to the first-stage planetary gear 4 or the second-stage planetary gear 5.

[0055] The first-stage planetary gear 4 and the second-stage planetary gear 5 have integrally protruding convex shafts at their shaft ends. The inner walls of the first radial perforated window 201 and the second radial perforated window 301 are both equipped with holes. The convex shafts are inserted into the holes to achieve shaft connection.

[0056] The beneficial effects of adopting the above technical solution are: using a stepped bearing diameter to match the variation of the hollow shaft inner diameter optimizes the distribution of the bearing bearing area; differentiated bearing configuration adapts to the load requirements of different shaft sections, extending the bearing service life; and the design of connecting the inner wall of the hollow window with the planetary gear shaft forms an auxiliary support structure to compensate for the slight deformation of the planetary carrier under heavy load conditions.

[0057] In some other embodiments of this utility model, the diameters of the first-stage sun gear 6 and the second-stage sun gear 7 are equal, and the diameters of the first-stage planetary gear 4 and the second-stage planetary gear 5 are equal.

[0058] The advantages of adopting the above technical solution are: by using a sun gear and planet gears with equal diameter design, a symmetrical distribution of the two-stage reduction ratio is achieved, simplifying the gear modification process and standardizing the machining process. Standardized tooth profile parameters allow for interchangeable spare parts, reducing maintenance costs.

[0059] In some other embodiments of this utility model, the shaft length of the internal gear ring 1 is not less than the sum of the shaft lengths of the first-stage gear set and the second-stage gear set, and the shaft length of the output shaft 2 is greater than the shaft length of the transmission shaft 3.

[0060] The beneficial effects of adopting the above technical solution are: the length of the internal gear ring 1 covers the axial working range of the double-stage gear set, ensuring continuous contact of the meshing tooth surfaces and avoiding pitting corrosion of the tooth surfaces caused by local stress concentration. The differentiated shaft length design of the output shaft 2 and the transmission shaft 3 provides installation margin for the output end connection structure and facilitates connection with external equipment (such as motors and output flanges).

[0061] In some other embodiments of the present invention, the outer wall of the internal gear ring 1 has a first outwardly extending flange portion 103 at one end near the first-stage gear set.

[0062] like Figure 7 As shown, the entire internal gear ring 1 is composed of a first tubular portion 102 and a first external flange portion 103.

[0063] The beneficial effects of adopting the above technical solution are as follows: the first outer flange portion 103 of the internal gear ring 1 forms a radially extending structure, similar to a flange, providing a housing for the entire planetary gear reducer and also providing a reliable axial limiting reference. The first outer flange portion 103 also provides an additional mounting and positioning surface for the internal gear ring 1, enhancing its structural strength after assembly with the joint motor. The first outer flange portion 103 can disperse the bolt tightening force, avoid local deformation, and ensure transmission stability.

[0064] In some other embodiments of this utility model, a first retaining ring 11 is assembled together with the outer wall of the output shaft 2 at one end of the internal gear ring 1. The inner wall of the internal gear ring 1 has a recessed first circumferential groove 104. The first circumferential groove 104 and the outer wall of the transmission shaft 3 are assembled together with a second retaining ring 12.

[0065] The beneficial effects of adopting the above technical solution are as follows: Through the mating assembly of the second retaining ring 12 and the first circumferential groove 104, dynamic sealing is achieved between the internal gear ring 1 and the hollow shaft, preventing displacement during transmission and preventing grease leakage. The retaining ring can be elastic; the preload design of an elastic retaining ring can adapt to dimensional changes caused by thermal expansion, avoiding stress concentration caused by rigid connections. Furthermore, the double retaining ring structure enhances the reliability of axial fixation and is suitable for high-frequency vibration or impact conditions.

[0066] Figure 5 , Figure 6 , Figure 7 These are all exploded views, intended to further facilitate understanding of the internal structure. Figure 5 , Figure 6 , Figure 7 The degree of circumferential explosion gradually increased. Figure 6 compared to Figure 5 , Figure 6 The output shaft 2 and transmission shaft 3 in the middle are axially separated. Figure 7 compared to Figure 6 , Figure 7 The components of the first-stage and second-stage gear sets are also pulled apart axially.

[0067] See Figures 8 to 13 The two-stage planetary gear reducer of the articulated motor of this application is used inside an axially compressed integrated robot articulated motor. The axially compressed integrated robot articulated motor includes: a stator-rotor assembly comprising a stator 36 and a rotor 35 arranged coaxially; a planetary gear reduction mechanism coaxially arranged radially inward of the stator-rotor assembly, comprising a gear set, a hollow shaft, and an internal gear ring 1; the hollow shaft encloses the gear set and has radially perforated windows exposing the planetary gears in the gear set; the planetary gears pass through the radially perforated windows and mesh with the inner wall of the internal gear ring 1; one of the stator 36 and rotor 35 is assembled to the shaft end of the gear set, and the other of the stator 36 and rotor 35 is assembled to the outer wall of the internal gear ring 1.

[0068] The beneficial effects of adopting the above technical solution are: by coaxially arranging the planetary gear reduction mechanism on the radial inner side of the stator-rotor assembly, the axial height of the motor and the reducer is integrated, significantly shortening the overall shaft length. The stator 36 and rotor 35 are respectively assembled with the gear set and the internal gear ring 1, forming a compact closed-loop path for power transmission, reducing energy loss, improving transmission efficiency, and meeting the requirements for lightweight and miniaturized robot joints.

[0069] In some other embodiments of this utility model, the stator 36 is annular, the rotor 35 is barrel-shaped, and the stator 36 is located in the cavity surrounded by the rotor 35.

[0070] The beneficial effects of adopting the above technical solution are: the nested layout of the annular stator 36 and the barrel-shaped rotor 35 maximizes the use of radial space and reduces axial occupancy. The stator 35 is located inside the cavity of the rotor 36, which shortens the magnetic field transmission path, enhances electromagnetic coupling efficiency, simplifies the heat dissipation channel design, and improves the heat dissipation performance of the motor.

[0071] In some other embodiments of this utility model, the inner wall of the stator 36 is assembled with the outer wall of the internal gear ring 1, and the rotor 35 includes a third tubular portion 3502 and an end plate portion 3501. The end plate portion 3501 covers one end of the third tubular portion 3502, and the centroid of the end plate portion 3501 is assembled with the shaft end of the gear set.

[0072] The end plate 3501 also has several axially perforated holes 3504 arranged in a ring to facilitate heat dissipation.

[0073] The beneficial effects of adopting the above technical solution are: the stator 36 is directly assembled with the outer wall of the internal gear ring 1, and the rotor 35 end plate is connected to the shaft end of the gear set, forming an axial force balance structure, avoiding vibration and wear caused by component misalignment. The integrated assembly of the inner wall of the stator 36 and the outer wall of the internal gear ring 1 reduces the number of independent support structures and shortens the transmission chain length.

[0074] In some other embodiments of this utility model, the outer wall of the stator 36 has a ring array of several iron cores 3601, and the inner wall of the rotor 35 has a ring array of several magnets 3503.

[0075] The stator 36 may include a coil flange 36, and the rotor 35 may include a magnetic flange 35. From Figure 10 From a longitudinal section perspective, and observing only one side of the stator and rotor assembly, the coil flange 36 and the magnetic flange 35 are arranged in two centrally symmetrical double L-shapes, which enclose the internal stator 36 and rotor 35.

[0076] The beneficial effects of adopting the above technical solution are: the symmetrical arrangement of the annular iron core on the outer wall of the stator 36 and the annular magnet on the inner wall of the rotor 35 optimizes the magnetic field distribution and improves the torque density. This design reduces magnetic leakage, lowers electromagnetic interference, and simplifies the coil winding process, thus reducing manufacturing costs.

[0077] In some other embodiments of the present invention, one end of the outer wall of the internal gear ring 1 has a first outer flange portion 103 extending radially outward, and the end plate portion 3501 and the first outer flange portion 103 are respectively located at both ends of the stator 36.

[0078] The beneficial effects of adopting the above technical solution are as follows: the outer flange of the internal gear ring 1 and the rotor end plate are partially distributed at both ends of the stator 36, forming a bidirectional axial limit, preventing axial movement of the gear set and stator-rotor assembly during high-speed operation. The outer flange also provides an additional assembly reference surface, improving the connection strength between the internal gear ring and the housing.

[0079] In some other embodiments of this utility model, the gear set includes a primary gear set and a secondary gear set. The primary gear set includes a primary sun gear 6 and several primary planetary gears 4 meshing with each other. The secondary gear set includes a secondary sun gear 7 and several secondary planetary gears 5 meshing with each other. The rotor 35 is assembled to the shaft end of the primary sun gear 6. The shaft length of the stator 36 is less than the shaft length of the internal gear ring 1, and the shaft length of the stator 36 is greater than the shaft length of the secondary sun gear 7.

[0080] The beneficial effects of adopting the above technical solution are: the coaxial layout of the two-stage planetary gear set, combined with the differentiated shaft length design, achieves a balance between high reduction ratio and compact axial dimensions. The stator shaft length of 36 is longer than that of the second-stage sun gear shaft of 7, ensuring that the stator effectively covers the second-stage gear set, avoiding exposure of the gear meshing area, and enhancing protection.

[0081] In some other embodiments of the present invention, the radial thickness of the stator 36 is greater than the radial thickness of the third tubular portion 3502.

[0082] The beneficial effects of adopting the above technical solution are: the radial thickness of the stator 36 is greater than that of the tubular portion of the rotor 35, which enhances the structural rigidity of the stator 36 and suppresses electromagnetic vibration noise. The thick-walled stator 36 can also accommodate more coil turns, increasing the motor output torque.

[0083] In some other embodiments of this utility model, the outer periphery of the rotor 35 is also covered by an input housing 32, the input housing 32 is assembled with the end plate portion 3501, and one end of the planetary gear reduction mechanism is also covered by an output flange 30. The input housing 32 and the output flange 30 constitute a cylindrical housing.

[0084] like Figure 12 As shown, the input housing 32 includes a second tubular portion 3201 and a second inner flange portion 3202, which together form a barrel-shaped structure similar to the rotor 35. The second tubular portion 3201 is coaxial with the third tubular portion 3502, and the second inner flange portion 3202 is parallel to the end plate portion 3501.

[0085] The beneficial effects of adopting the above technical solution are: the input housing 32 and the output flange 30 form an integrated cylindrical shell, simplifying the external structure, improving the protection level, and providing reliable mechanical protection. The distributed connection of the bolt group enhances the structural strength of the shell and adapts to the load transfer requirements under complex working conditions.

[0086] In some other embodiments of this utility model, the output flange 30 is assembled with the first outer flange portion 103 of the internal gear ring 1 by a third bolt group 40, and the output flange 30 is assembled with the input housing 32 by a second bolt group 40.

[0087] like Figure 11 and Figure 12 As shown, the outer end of the output flange 30 can also be covered by an output end cover plate 31. The output end cover plate 31, the output flange 30, and the first outer flange portion 103 of the internal gear ring 1 are all passed through and fixed by the third bolt group 40.

[0088] The beneficial effects of adopting the above technical solution are: the output flange 30 is connected to the internal gear ring 1 and the input housing 32 by multiple sets of bolts, which disperses the fastening stress and avoids local deformation. The third bolt group 40 is fixed together with the output end cover plate 31, which enhances the torsional resistance of the output end and adapts to high load conditions.

[0089] In some other embodiments of this utility model, the input housing 32 is also fixed with a drive housing flange 33 at the end opposite to the output flange 30, and the drive housing flange 33 partially encloses the drive plate 34.

[0090] The outer contour of the drive housing flange 33 is frustoconical. The drive housing flange 33 also has a radial side opening 3301, which exposes the internal drive board 34, on which electrical components 3401 can be mounted. The side opening 3301 serves a combination of heat dissipation, assembly and maintenance, and functional expansion. Firstly, the side opening 3301 acts as a heat dissipation channel, reducing the operating temperature of power components (such as MOSFETs and driver chips) on the drive board 34 (e.g., a PCB board) through air convection. It also exposes part of the circuitry for easy signal monitoring with probes or connection to a programming interface during debugging. Secondly, it provides a path for cables (such as power lines and encoder signal lines), preventing bending damage, and may serve as a reference for the assembly positioning of the housing and internal components, reducing installation interference.

[0091] In addition, such as Figure 12 As shown, the first bolt group 8 is fixed to the second-stage sun gear. The first bolt group 8, the second bolt group 39, and the third bolt group 40 each include several bolts. The first bolt group 8 is also equipped with a rear end cap 37.

[0092] The planetary gear reduction mechanism is also equipped with a cable outlet partition 38 on its outer side, such as... Figure 12 As shown, the inner wall of the input housing 32 also has a groove to accommodate the output partition 38.

[0093] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They should not be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A two-stage planetary gear reducer for a joint motor, characterized in that, include: The first-stage gear set includes a first-stage sun gear and several first-stage planet gears that mesh with each other; The second-stage gear set includes a meshing second-stage sun gear and several second-stage planet gears; A hollow shaft includes an output shaft and a transmission shaft that respectively enclose a first-stage gear set and a second-stage gear set. The hollow shaft includes a radially hollowed-out window for exposing the first-stage or second-stage planetary gear. The internal gear ring has an inner wall including internal teeth that mesh with the first-stage and second-stage planetary gears; The first-stage gear set and the second-stage gear set are arranged coaxially along the axial direction, and the internal gear ring is arranged coaxially outside the hollow shaft.

2. The two-stage planetary gear reducer for the joint motor according to claim 1, characterized in that: The first-stage sun gear includes a first gear tooth segment, and the first-stage sun gear has a first optical axis segment at both ends of the first gear tooth segment. The second-stage sun gear includes a second gear tooth segment, and the second-stage sun gear has a second optical axis segment at the end of the second gear tooth segment opposite to the first-stage sun gear. The first gear segment meshes with the first-stage planetary gear, and the second gear segment meshes with the second-stage planetary gear.

3. The two-stage planetary gear reducer for the joint motor according to claim 2, characterized in that: The shaft length of the first gear segment is greater than the shaft length of the second gear segment; The number of primary or secondary planetary gears ranges from three to six.

4. The two-stage planetary gear reducer for the joint motor according to claim 2, characterized in that: A first bearing is fitted on a first optical shaft segment that is away from the second optical shaft segment, and a second bearing is fitted on the second optical shaft segment. The second-stage sun gear is fitted with a first bolt set at the end opposite to the first-stage gear set.

5. The two-stage planetary gear reducer for the joint motor according to claim 4, characterized in that: Each radially perforated window allows a primary planetary gear or a secondary planetary gear to pass through, and the circumferential width of the radially perforated window is less than the diameter of the primary or secondary planetary gear.

6. The two-stage planetary gear reducer for the joint motor according to claim 5, characterized in that: The diameter of the first bearing is smaller than that of the second bearing, and the outer rings of the first bearing and the second bearing are respectively assembled with the inner walls of the output shaft and the transmission shaft. The inner wall of the radially perforated window is axially connected to the first-stage or second-stage planetary gear.

7. The two-stage planetary gear reducer for the joint motor according to claim 1, characterized in that: The diameters of the first-stage sun gear and the second-stage sun gear are equal, and the diameters of the first-stage planetary gear and the second-stage planetary gear are equal.

8. The two-stage planetary gear reducer for the joint motor according to claim 1, characterized in that: The shaft length of the internal gear ring is not less than the sum of the shaft lengths of the first-stage gear set and the second-stage gear set, and the shaft length of the output shaft is greater than the shaft length of the transmission shaft.

9. The two-stage planetary gear reducer for the joint motor according to claim 1, characterized in that: The outer wall of the internal gear ring has a first outwardly extending flange at one end near the first-stage gear set.

10. The two-stage planetary gear reducer for the joint motor according to claim 1, characterized in that: One end of the internal gear ring is fitted with a first retaining ring together with the outer wall of the output shaft. The inner wall of the internal gear ring has a recessed first circumferential groove. The first circumferential groove and the outer wall of the transmission shaft are fitted with a second retaining ring together.

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