A robot joint reducer device and working method

Abstract

The present invention provides a robot joint reducer device and a working method, which relate to the field of joint reducers. In view of the problem that current robot reducers are difficult to meet the needs of a large reduction ratio while achieving high-rigidity transmission and clearance compensation, three series-connected reduction transmissions are constructed to effectively increase the reduction ratio. The return clearance of the three-stage reduction transmission is eliminated through the helical planetary gear structure of the three-stage reduction transmission. Two driving elements are used to apply a reverse torque to the secondary driven gear through the secondary driving gear, which not only achieves the effective elimination of the return clearance of the first-stage reduction transmission and the second-stage reduction transmission, but also enhances the rigidity of the entire reducer in combination with the helical gear transmission of the three-stage reduction transmission, thereby significantly improving the working performance and reliability of the robot.

Description

Technical Field

[0001] The present invention relates to the field of joint reducers, and in particular to a robot joint reducer device and a working method. Background Art

[0002] Industrial robot joints typically use high-precision reducers and servo motors to achieve power transmission, and their design focuses on high stiffness and high load capacity. However, mechanical damage such as wear on the gear meshing surfaces and increased bearing clearance caused by long-term operation will produce backlash, resulting in an angular difference in idle motion between the input and output shafts of the transmission system, which directly affects the robot's repeatability. In high-speed commutation or precision assembly scenarios, the vibration and error accumulation caused by the gap will seriously affect the robot's accuracy and reliability. There is currently a lot of research on gap elimination technology for robot joint reducers, mainly including mechanical preload methods, sensor compensation methods, variable stiffness structures and other methods. Among them, the mechanical preload method reduces the gap by adjusting the gear preload force, but excessive preload force will increase friction loss, reduce transmission efficiency, and cannot dynamically adapt to wear changes; the sensor compensation method uses an encoder to monitor the gap and compensates for the error through a control algorithm, but this method relies on high-precision sensors and complex control models, which is costly and has limited real-time performance, making it difficult to cope with sudden load changes; the variable stiffness structure relies on permanent magnetic springs to reconstruct the joints and change the joint stiffness by adjusting mechanical variables, but its dynamic response speed is slow, and it is difficult to take into account both high stiffness and low energy consumption requirements.

[0003] A Chinese patent (publication number CN114877032A, publication date 20220809) discloses a large-torque and high-rigidity robot joint reducer. The left and right gears in the planetary triple gear are simultaneously engaged with the double-row sun gear arranged on the input shaft and the inner ring gear embedded in the left and right connecting plates to realize primary transmission. The intermediate gear of the planetary triple gear is engaged with the output ring gear to realize secondary transmission; this makes the transmission structure compact and the transmission efficiency high, but it still has the problem of large gear return meshing gap, and the reduction ratio of the secondary reduction transmission it adopts is difficult to meet the requirements, and it is difficult to take into account the requirements of large reduction ratio while achieving high-rigidity transmission and gap compensation. Summary of the Invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a robot joint reducer device and working method, construct three series-connected reduction transmissions, effectively increase the reduction ratio, eliminate the return clearance of the three-stage reduction transmission through the helical planetary gear structure of the three-stage reduction transmission, and utilize two driving elements to apply reverse torque to the secondary driven gear through the secondary driving gear, which not only achieves the effective elimination of the return clearance of the first-stage reduction transmission and the secondary reduction transmission, but also enhances the stiffness of the entire reducer in combination with the helical gear transmission of the three-stage reduction transmission, thereby significantly improving the working performance and reliability of the robot.

[0005] The first object of the present invention is to provide a robot joint reducer device, which adopts the following scheme:

[0006] include:

[0007] The three-stage reduction transmission adopts a helical planetary gear structure. Two sets of planetary gears with opposite rotation directions are installed on the planet carrier, which mesh with the sun helical gear shaft respectively. The end of the sun helical gear shaft is equipped with an axial elastic mechanism to apply axial elastic preload to the sun helical gear shaft to eliminate the return clearance of the three-stage reduction transmission. The planet carrier is connected to a follower cover as the output end.

[0008] A two-stage reduction transmission, comprising a secondary driven gear and a secondary driving gear. The secondary driven gear is mounted on the sun helical gear shaft and rotates at a constant angular velocity. The two secondary driving gears are respectively engaged with the secondary driven gears.

[0009] The first-stage reduction transmission is equipped with two groups of matched two-stage driving gears. Each group of the first-stage reduction transmission includes a meshing first-stage driving bevel gear and a first-stage driven bevel gear. The first-stage driven bevel gear and the second-stage driving gear rotate coaxially with the same angular velocity. The first-stage driving bevel gear is connected to the driving element; the two driving elements apply reverse torque to the second-stage driven gear through the second-stage driving gear to eliminate the return clearance between the first-stage reduction transmission and the second-stage reduction transmission.

[0010] Furthermore, the first-stage driving bevel gear is a hypoid spiral bevel gear shaft, the first-stage driven bevel gear is an end face spiral bevel gear, and the driving element is located outside one end of the second-stage driven gear and is distributed toward the axis of the sun helical gear shaft.

[0011] Furthermore, the two secondary driving gears are arranged symmetrically relative to the axis of the sun helical gear shaft.

[0012] Furthermore, the axes of the first-stage driving bevel gears connected to the two driving elements are distributed in parallel, and the axes of the first-stage driving bevel gear and the first-stage driven bevel gear in the same group are perpendicular.

[0013] Furthermore, the three-stage reduction transmission also includes an outer ring gear that cooperates with the planetary gear set, and the outer ring gear is connected to an end cover. One end of the sun helical gear shaft rotates to cooperate with the end cover, and the other end rotates to cooperate with the follower cover. An axial movement allowance is left between the sun helical gear shaft and the planetary gear set.

[0014] Furthermore, the axial elastic mechanism includes an axial sliding block, a wave spring and a pre-tightening nut cover. The sun helical gear shaft passes through a tapered roller bearing and a matching end cover. The axial sliding block abuts against an outer ring of the tapered roller bearing. The pre-tightening nut covers the end cover, and the wave spring abuts between the pre-tightening nut cover and the axial sliding block.

[0015] Furthermore, the planetary carrier includes a transmission shaft, the planetary gear set is mounted on the transmission shaft, and the planetary gear set meshes with the outer ring gear.

[0016] Furthermore, the planet carrier also includes planet carrier 1 and planet carrier 2 axially spaced apart along the sun bevel gear shaft, wherein one set of planetary gear sets is located between planet carrier 1 and planet carrier 2, and another set of planetary gear sets is located between planet carrier 2 and the follower cover.

[0017] A second object of the present invention is to provide a working method of the robot joint reducer device as described in the first object, comprising:

[0018] The follower cover is connected to the external actuator;

[0019] During movement, one driving element outputs a positive driving torque as the main driving element, and the other driving element outputs a reverse torque as the auxiliary driving element, which is smaller than the positive driving torque, to keep the reverse tooth surfaces of the first-stage driven bevel gear meshing with the first-stage driving bevel gear, and at the same time ensure the reverse tooth surfaces of the second-stage driving gear and the second-stage driven gear meshing, thus eliminating the return clearance between the first-stage reduction transmission and the second-stage reduction transmission;

[0020] The sun helical gear shaft produces axial displacement, driving the two sets of planetary gear sets with opposite rotation directions to rotate at opposite angles, so that the sun helical gears on the sun helical gear shaft are respectively close to the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the return clearance of the three-stage reduction transmission;

[0021] The driving element drives the follower cover to output power after passing through the first-stage reduction transmission, the second-stage reduction transmission and the third-stage reduction transmission in sequence.

[0022] Furthermore, the preload force of the axial elastic mechanism is adjusted so that the sun helical gear shaft can engage with opposite tooth surfaces of the two sets of planetary gear sets at the same time.

[0023] Compared with the prior art, the present invention has the following advantages and positive effects:

[0024] To address the current difficulty of achieving both high-speed transmission and backlash compensation in robot reducers, a three-stage helical planetary gear structure is constructed, effectively increasing the reduction ratio. Two sets of planetary gears with opposite rotation directions are mounted on the planetary carrier through a three-stage helical planetary gear structure. Combined with an axial elastic mechanism at the end of the sun helical gear shaft, an axial elastic preload is applied to the sun helical gear shaft. This preload ensures that the two sets of planetary gears maintain close contact during both forward and reverse transmission, thereby eliminating the backlash of the three-stage reduction transmission and improving transmission accuracy and stability. Two drive elements apply reverse torque to the secondary driven gear via the secondary driving gear, effectively eliminating the backlash of the primary and secondary reduction transmissions. Furthermore, the helical gear transmission of the three-stage reduction transmission enhances the stiffness of the entire reducer. When the robot joints are subjected to heavy loads, the reducer's high stiffness effectively resists deformation and vibration, ensuring stable operation of the robot. The multi-stage reduction transmission increases torque output, significantly improving the robot's performance and reliability, and extending its service life.

[0025] Among them, the three-stage reduction transmission adopts a bidirectional planetary helical gear synchronous parallel transmission. By applying axial static preload force to the sun helical gear shaft, a difference in the planetary gear meshing angle is formed, thereby eliminating the bidirectional tooth surface clearance of the planetary gear set, so that the robot joint can meet the requirements of a large reduction ratio while achieving high-rigidity transmission and clearance compensation.

[0026] The overall compact design meets the requirements of narrow space layout of robot joints. The first-stage reduction transmission adopts bevel gear transmission. The first-stage active bevel gear is a hyperbolic spiral bevel gear shaft, and the first-stage driven bevel gear is an end face spiral bevel gear. The axis is vertical. The hyperbolic spiral bevel gear structure is used to transmit torque. At the same time, the driving element is biased towards the axis of the sun helical gear shaft, which reduces the axial and radial dimensions of the reducer and prevents interference during the operation of the robot. The use of wave springs can reduce the axial dimension compared to traditional compression springs.

[0027] The sun helical gear shaft in the reducer is subjected to axial preload through a corrugated spring. Combined with the adjustable clearance feature of the tapered roller bearing, it can dynamically compensate for the expansion of the clearance caused by tooth surface wear, thereby improving the working stability of the robot joint reducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 1 is an exploded view of a robot joint reducer device in one or more embodiments of the present invention.

[0030] Figure 2 Schematic diagram of the assembly of a robot joint reducer device in one or more embodiments of the present invention.

[0031] Figure 3 2 is a diagram of the internal gear structure of a robot joint reducer device in one or more embodiments of the present invention.

[0032] Figure 4 1. An exploded view of a left-handed planetary gear set in a robot joint reducer device in one or more embodiments of the present invention.

[0033] Figure 5 An exploded view of a right-hand planetary gear set of a robot joint reducer device in one or more embodiments of the present invention.

[0034] Figure 6 This is an exploded view of the planet carrier 2 of the robot joint reducer device in one or more embodiments of the present invention.

[0035] Figure 7 It is a transmission diagram of the robot joint reducer device in one or more embodiments of the present invention.

[0036] Among them: 1. Hyperbolic spiral bevel gear shaft; 2. End spiral bevel gear; 3. Pre-tightening bolt; 4. Servo motor; 5. Spur gear; 6. Spur gear shaft; 7. Sun helical gear shaft; 8. Left-handed planetary gear set; 9. Right-handed planetary gear set; 10. Transmission shaft; 11. Outer ring gear; 12. Deep groove ball bearing 2; 13. Deep groove ball bearing 3; 14. Bushing 1; 15. Tapered roller bearing 1; 16. Tapered roller bearing 2; 17. Bushing 2; 18. Planet carrier 1; 19. Tapered roller bearing 3; 20. Deep groove ball bearing 4; 21. Planet carrier 2; 22. Follower cover; 23. Deep groove ball shaft Bearing 6; 24. Shaft retaining ring 2; 25. Rotary seal 1; 26. Hole retaining ring 2; 27. Tapered roller bearing 4; 28. Rotary seal 2; 29. ​​Hole retaining ring 3; 30. End cover 1; 31. Bolt 1; 32. O-ring 1; 33. Axial sliding block; 34. Wave spring; 35. Preload screw cap; 36. End cover 2; 37. Bolt 2; 38. O-ring 2; 39. Bolt 3; 40. O-ring 3; 211. Planet carrier; 212. Deep groove ball bearing 5; 213. Hole retaining ring 1; 801. Left-handed planetary gear; 802. Deep groove ball bearing 1; 901. Right-handed planetary gear. DETAILED DESCRIPTION

[0037] Example 1

[0038] In a typical embodiment of the present invention, Figure 1-Figure 7 As shown, a robot joint reducer device is given.

[0039] Current high-torque, high-rigidity robot joint reducers, while offering the advantages of compact transmission structure and high transmission efficiency, suffer from large gear return meshing clearances, which affect transmission accuracy and stability. In some robotic applications requiring extremely high precision, large return clearances can lead to positioning deviations and other issues during robot motion. Furthermore, the two-stage reduction transmission method employed in these reductions has limitations in terms of reduction ratios, making it difficult to meet the requirements for large reduction ratios. When a high reduction ratio is required to achieve low-speed, high-torque output, high-rigidity transmission and clearance compensation cannot be achieved simultaneously, resulting in deformation and vibration of the robot joints when under heavy loads, seriously affecting the robot's performance and service life. Based on this, the present embodiment provides a robot joint reduction device that constructs three reduction transmissions in series, effectively increasing the reduction ratio. The three-stage reduction transmission's helical planetary gear structure eliminates the return clearance of the three-stage reduction transmission. Two drive elements apply reverse torque to the secondary driven gear through the secondary driving gear, effectively eliminating the return clearances of the primary and secondary reduction transmissions. Furthermore, the helical gear transmission of the three-stage reduction transmission enhances the rigidity of the entire reducer, significantly improving the robot's performance and reliability.

[0040] Specifically, such as Figure 1-Figure 3 As shown, the robot joint reducer device includes a first-stage reduction transmission, a second-stage reduction transmission and a third-stage reduction transmission connected in series in sequence. The first-stage reduction transmission adopts a bevel gear structure transmission with a vertical distribution of 90° angles to meet the reduction transmission requirements, and at the same time it is convenient for the position distribution of the driving element as the power input to reduce the occupied space; the second-stage reduction transmission adopts a spur gear transmission, and a second-stage driven gear cooperates with two second-stage driving gears to input reverse torque to achieve the effect of eliminating the return clearance; the third-stage reduction transmission adopts a planetary gear reduction mechanism, which is a helical planetary gear structure. It adopts two sets of planetary gear sets combined with the sun helical gear shaft 7 with an axial elastic mechanism to achieve the sliding of the sun helical gear shaft 7, and maintain the sun helical gear shaft 7 and the planetary gear set in close transmission in the forward and reverse directions.

[0041] like Figure 3 As shown, the three-stage reduction transmission adopts a helical planetary gear structure. Two sets of planetary gear sets with opposite rotation directions are mounted on the planet carrier 211, which respectively mesh with the sun helical gear shaft 7. The end of the sun helical gear shaft 7 is equipped with an axial elastic mechanism to apply an axial elastic preload to the sun helical gear shaft 7 to eliminate the return clearance of the three-stage reduction transmission. The planet carrier 211 is connected to the follower cover 22 as the output end.

[0042] like Figure 2 As shown, the two-stage reduction transmission includes a two-stage driven gear and a two-stage driving gear. The two-stage driven gear is mounted on the sun helical gear shaft 7 and rotates at a constant angular velocity. The two two-stage driving gears are respectively engaged with the two-stage driven gears.

[0043] like Figure 1 and Figure 2 As shown, the primary reduction transmission is provided with two groups of matched secondary driving gears. Each group of primary reduction transmission includes a meshing primary driving bevel gear and a primary driven bevel gear. The primary driven bevel gear and the secondary driving gear rotate coaxially with each other at the same angular velocity. The primary driving bevel gear is connected to the driving element. The two driving elements apply reverse torque to the secondary driven gear through the secondary driving gear to eliminate the return clearance between the primary reduction transmission and the secondary reduction transmission.

[0044] The two drive elements each drive two sets of primary driving bevel gears, which in turn rotate the meshing primary driven bevel gears. The primary driven bevel gears are coaxial with the secondary driving gears, thus transmitting power to the secondary driving gears. The two drive elements apply counter-torque to the secondary driven gears through the secondary driving gears, simultaneously compensating for backlash while transmitting power. The two secondary driving gears mesh with the secondary driven gears, transferring power from the primary reduction gear to the secondary driven gears. Due to the different gear ratios between the secondary driving gears and the secondary driven gears, a two-stage reduction is achieved. The secondary driven gears rotate the sun helical gear shaft 7. Input power is transmitted through the sun helical gear shaft 7, which drives two sets of planetary gears with opposite rotation directions to rotate about their own axes. Simultaneously, the planetary gears orbit around the sun helical gear shaft 7, constrained by the planet carrier 211. Speed ​​reduction is achieved due to the gear ratios between the planetary gear sets and the sun helical gear shaft 7, as well as the kinematic relationship between the planet carrier 211 and the planetary gear sets. The follower cover 22, connected to the planet carrier 211, serves as the output terminal, outputting the power after the three-stage reduction.

[0045] like Figure 7 As shown in the figure, multi-stage reduction significantly increases the reduction ratio through the coordination of three-stage, two-stage, and one-stage reduction transmissions. The different levels of gear transmission, through the appropriate number of teeth, can convert high-speed input power into low-speed, high-torque output power, meeting the robot joint's requirement for a large reduction ratio and enabling more precise and stable low-speed motion during operation.

[0046] like Figure 3 As shown, for a single-stage reduction transmission, the axes of the primary driving bevel gears connected to the two drive elements are parallel, and the axes of the primary driving bevel gears and the primary driven bevel gears in the same group are perpendicular. The primary driving bevel gear is a hypoid spiral bevel gear shaft 1, and the primary driven bevel gear is an end face spiral bevel gear 2. Specifically, both sets of primary reduction transmissions use a 90° vertical transmission. The hypoid spiral bevel gears are formed on the hypoid spiral bevel gear shaft 1, and the drive element uses a servo motor 4. The drive element is located outside one end of the secondary driven gear and is offset from the axis of the sun helical gear shaft 7, as shown in FIG. Figure 3As shown, the two secondary driving gears are arranged symmetrically with respect to the axis of the sun bevel gear shaft 7, and the two driving elements are also arranged symmetrically.

[0047] It should be noted that a compact structure is adopted to meet the requirements of narrow space layout of the robot joints. The first-stage reduction transmission adopts bevel gear transmission with a vertical axis, which reduces the axial space along the sun helical gear shaft 7. The driving element is distributed toward the axis of the sun helical gear shaft 7, which reduces the space occupied by the driving element's outward deflection, reduces the axial and radial dimensions of the reducer, and prevents interference during the operation of the robot.

[0048] In this embodiment, a coupling hole is defined at the end of the hypoid spiral bevel gear shaft 1, which is secured to servo motors 44 via preload bolts 3. The input torque of the two servo motors 4 is transmitted to the end spiral bevel gears 2 via the two hypoid spiral bevel gear shafts 1. During operation, one servo motor 4 functions as the main motor, outputting a forward drive torque, while the other servo motor 4, acting as an auxiliary motor, applies a small reverse torque to ensure reverse tooth engagement, thereby eliminating backlash in the primary reduction transmission. The direction of the joint torque output can be changed by switching the main drive source.

[0049] like Figure 2 and Figure 3 As shown, for the two-stage reduction transmission, the secondary driven gear is a spur gear 5, and the secondary driving gear is a spur pinion. The spur pinions are distributed on a spur gear shaft 6. One spur gear 5 and two spur gear shafts 6 mesh in opposite directions. The end spiral bevel gears 2 are connected to the spur gear shafts 6 via a flat key interference fit, allowing the primary driven bevel gear and the secondary driving gear to rotate coaxially and at the same angular velocity. The input torque of the two end spiral bevel gears 2 is transmitted from the spur gear shaft 6 to the spur gear 5. Since the input torque is in opposite directions, the spur gear shaft 6 always has a tooth surface in contact with the spur gear 5 during reversing, eliminating the return clearance of the secondary reduction transmission.

[0050] like Figure 1 、 Figure 2 and Figure 3 As shown, the three-stage reduction transmission also includes an outer ring gear 11 that cooperates with the planetary gear set. The outer ring gear 11 is connected to an end cover. One end of the sun bevel gear shaft 7 rotates to cooperate with the end cover, and the other end rotates to cooperate with the follower cover 22. An axial movement allowance is left between the sun bevel gear shaft 7 and the planetary gear set.

[0051] Specifically, the three-stage reduction transmission adopts a helical planetary gear structure. Two sun helical gears are formed on the sun helical gear shaft 7, which respectively mesh with two sets of planetary gear sets, one of which is a left-handed planetary gear set 8 and the other is a right-handed planetary gear set 9. Figure 3As shown, each planetary gear set includes three planetary gears. The left-handed planetary gear set 8 includes three left-handed planetary gears 801, which are evenly distributed along the circumference of the sun helical gear shaft 7 and mesh with the same sun helical gear; the right-handed planetary gear set 9 includes three right-handed planetary gears 901, which are evenly distributed along the circumference of the sun helical gear shaft 7 and mesh with the same sun helical gear; the left-handed planetary gears 801 and the right-handed planetary gears 901 are equipped with a transmission shaft 10 and are installed on the planet carrier 211 through the transmission shaft 10, and the planetary gears are meshed with the outer ring gear 11.

[0052] Specifically, the sun helical gear shaft 7 is connected to the spur gear 5 via an involute spline interference fit. The outer circumference of the sun helical gear shaft 7 is machined with left-handed and right-handed helical teeth spaced axially apart, forming the sun gears of the meshing planetary gear sets. The left-handed planetary gear set 8 and the right-handed planetary gear set 9 are mounted on the transmission shaft 10 in the same direction as the helical teeth on the outer surface of the sun helical gear shaft 7. The inner surface of the outer ring gear 11 is machined with left-handed and right-handed helical teeth in the same direction as the helical teeth on the sun helical gear shaft 7. The left-handed planetary gears 801 and the right-handed planetary gears 901 are coupled to the same transmission shaft 10, with three left-handed planetary gears 801 corresponding to three transmission shafts 10.

[0053] Planet carrier 1 18 and planet carrier 2 21 are axially spaced apart along the sun bevel gear shaft 7 , wherein the left-handed planetary gear set 8 is located between planet carrier 18 and planet carrier 2 21 , and the right-handed planetary gear set 9 is located between planet carrier 2 21 and the follower cover 22 .

[0054] The input torque of the spur gear 5 is transmitted to the two sets of planetary gear sets through the sun helical gear shaft 7. Due to the existence of two sets of oppositely directed planetary helical gears output in parallel, an axial micro-displacement is generated through the sun helical gear shaft 7, driving the left-handed planetary gear set 8 and the right-handed planetary gear set 9 to rotate at opposite micro-angles, so that the two gears are respectively pressed against the opposite tooth surfaces on the sun helical gear shaft 77, thereby eliminating the return clearance of the three-stage reduction transmission.

[0055] Specifically, in the two-stage reduction transmission, a deep groove ball bearing 2 12 is provided at the top of the spur gear shaft 6, and a deep groove ball bearing 3 13 is provided at the bottom. A shaft sleeve 14 is provided between the inner ring of the deep groove ball bearing 2 12 and the axial end face spiral bevel gear 2 for axial limitation, and the inner ring of the deep groove ball bearing 3 1313 is axially limited by the shoulder of the spur gear shaft 6.

[0056] Specifically, in the three-stage reduction transmission, a tapered roller bearing 15 is set at the top of the sun helical gear shaft 7, and a tapered roller bearing 2 16 is set at the bottom. In order to ensure the smooth axial transmission of the sun helical gear shaft 7, the tapered roller bearing 15 and the tapered roller bearing 2 16 are installed face to face, and a shaft sleeve 2 17 is set between the inner ring of the tapered roller bearing 15 and the spur gear 5 for axial limitation, and the inner ring of the tapered roller bearing 2 16 is axially limited by the shaft shoulder of the sun helical gear shaft 7.

[0057] like Figure 4 and Figure 5 As shown, the left-handed planetary gear set 8 includes a left-handed planetary gear 801 and two deep groove ball bearings 802. A bearing seat is set in the middle of the inner ring of the left-handed planetary gear 801. The outer rings of the two deep groove ball bearings 802 are axially positioned with the left-handed planetary gear 801 using an interference fit and are installed in the bearing seat in opposite directions; the right-handed planetary gear set 9 includes a right-handed planetary gear 901 and two deep groove ball bearings 802. The installation method is the same as that of the left-handed planetary gear set 8.

[0058] like Figure 1 、 Figure 2 、 Figure 3 and Figure 6 As shown, in order to support the uniform and stable operation of the planetary gear set, a planet carrier 18 is arranged between the spur gear 5 and the left-hand planetary gear set 8. The bearing seat hole is processed in the center of the planet carrier 18, and three planetary bearing seat holes are processed and evenly distributed along the circumference. The center bearing seat hole and the spur gear 5 are supported for rotation by a tapered roller bearing 3 19. The tapered roller bearing 3 19 and the tapered roller bearing 15 are installed face to face. The planetary bearing seat hole and the transmission shaft 10 are supported for transmission by a deep groove ball bearing 4 20; at the same time, in order to further enhance the operating stability of the planetary gear set and reduce the vibration during power transmission, a planet carrier 21 is arranged between the left-hand planetary gear set 8 and the right-hand planetary gear set 9, wherein an avoidance hole is processed in the center of the planet carrier 21, and three planetary bearing seat holes are processed and evenly distributed along the circumference. A deep groove ball bearing 5 212 is arranged in the planetary bearing hole to support the rotation, and a retaining ring 213 is used for axial limitation through the hole. The transmission shaft 10 passes through the inner ring of the deep groove ball bearing 5 212 and is axially limited by the shaft shoulder.

[0059] Specifically, a follower cover 22 is provided at the end of the transmission shaft 10 to output the reducer torque. The follower cover 22 has three bearing seat holes evenly arranged axially, housing deep groove ball bearings 6 23, supporting the rotation of the three transmission shafts 10. The inner ring of the bearing is axially limited by a shaft retaining ring 24. To enhance the reducer's sealing performance and prevent the intrusion of external dust and impurities into the reducer, a rotary seal 1 25 is provided between the follower cover 22 and the transmission shaft 10, axially limited by a hole retaining ring 26. A bearing seat hole is provided in the center of the follower cover 22 to house a tapered roller bearing 2 16, supporting the rotation of the sun bevel gear shaft 7. The surface of the follower cover 22 is evenly circumferentially threaded, which are used with fasteners to connect to the load end of the robot joint. The number and size of the threaded holes are provided as required and are not further specified in this embodiment.

[0060] Specifically, cylindrical rollers are positioned between the follower cover 22 and the outer gear ring 11. The follower cover 22 serves as the inner bearing ring, while the outer gear ring 11 serves as the outer bearing ring, creating a tapered roller bearing 27 supporting the transmission. The tapered roller bearing 27 consists of cylindrical rollers and a retaining cage. The contact surfaces between the follower cover 22 and the outer gear ring 11 are machined into conical surfaces to meet the requirements of the bearing roller raceway, serving as the inner and outer bearing rings. To prevent leakage of lubricating media and dust from entering the reducer, a rotary seal 28 is positioned between the outer gear ring 11 and the follower cover 22, with a retaining ring 29 providing axial restraint. Threaded holes are uniformly distributed axially at the bottom end of the outer gear ring 11, which connect to the robot joint input terminal with fasteners. The number and size of the threaded holes are determined as required and are not specified in this embodiment.

[0061] Specifically, an end cap 30 is mounted on the top of the outer gear ring 11, and the two are fastened together by bolts 31. An O-ring 32 is installed between the end cap 30 and the outer gear ring 11 for sealing. The O-ring can be replaced with a gasket or other sealing element as needed, and the specific sealing method can be selected to meet the sealing requirements. A bearing seat with a slot is located in the center of the end cap 30, supporting the tapered roller bearing 15. The upper surface of the bearing seat is sequentially provided with an axial sliding block 33, a wave spring 34, and a preload screw cap 35. By tightening the preload screw cap 35, the wave spring 34 is compressed to generate an axial load, pushing the sliding block axially along the bearing seat slot. The sliding block applies preload to the outer ring of the tapered roller bearing 15, thereby forcing a micro-axial displacement of the sun helical gear shaft 77. The preload force can be adjusted in real time according to the load. The tapered roller bearings 15, 16, and 19 on the sun helical gear shaft 7 all use adjustable clearance bearings.

[0062] Specifically, in order to compress the transmission shaft 10 into space, two windows are opened opposite to each other at the top of the end cover 30 to allow the meshing surface of the end spiral bevel gear 2 to extend out, and the end cover 2 36 is respectively installed on the two windows and fastened by the bolt 2 37. An O-ring 2 38 is set between the end cover 2 36 and the end cover 1 30 for sealing.

[0063] Specifically, an integrated casting channel is formed on the side of the second end cover 36, covering the hyperbolic spiral bevel gear shaft 1 and the motor shaft. The channel direction is staggered to save the installation space of the reducer. A motor mounting hole is set at the end of the channel, and the servo motor 4 is fastened by a third bolt 39. An O-ring 3 40 is set between the motor and the second end cover 36 for sealing.

[0064] Combine Figure 7 , the working principle of the high stiffness robot joint reducer device is explained in detail.

[0065] The robot joint reducer has three stages of reduction transmission: primary, secondary, and tertiary. During installation, the reducer is filled with lubricant. Seals within the reducer effectively prevent leakage and impurities. The type of lubricant is selected based on actual usage requirements and is not specifically specified here.

[0066] The first-stage reduction transmission structure utilizes two sets of spiral bevel gears arranged at 90° angles, each inputted in parallel by two servo motors 4, achieving a transmission ratio of 1:1 to 1:5. During the operation of the reducer, based on the output requirements of the robot's joint load end, servo motor 4 can be divided into motor A outputting a forward drive torque T1, and motor B applying a reverse preload torque T2 = (0.05-0.1) T1, ensuring that the reverse tooth surface of the spiral bevel gear driven by motor B is always continuously compressed. When the reducer changes direction, the torque vectoring active control algorithm adjusts the torque direction and magnitude of the two motors in real time, ensuring that the gear meshing surfaces maintain constant preload contact under alternating loads, achieving zero backlash during the first-stage reduction transmission.

[0067] The secondary reduction transmission structure utilizes parallel spur gears, achieving a transmission ratio of 1:5 to 1:20. Torque is input to the spur gear 5 via the spur gear shaft 6, which is fixedly connected to the two sets of end spiral bevel gears 2. Because the torque output from the primary reduction transmission is in the opposite direction, the meshing tooth surfaces of the spur gear shaft 6 and the spur gear 5 maintain bidirectional contact, thus achieving zero backlash during the secondary reduction transmission.

[0068] The three-stage reduction transmission structure utilizes a helical planetary gear transmission, with a transmission ratio of 1:1 to 1:5. The planetary gears are driven by two parallel sets of planetary gears. These two sets of gears have identical parameters, except for the opposite helix angles. The number of planetary gears in each set depends on the transmission's design load, typically three or four. A greater number of planetary gears carries a greater load, but this embodiment does not impose specific requirements. The transmission is transmitted to the planetary gears via the sun helical gear shaft 7, which is fixed to the spur gear 5. The outer ring gear 1111 serves as a fixed component. The outer ring of the tapered roller bearing 15 at the top of the sun helical gear shaft 7 is clearance-fitted with the end cap 30. A groove is machined into the corresponding end face of the bearing seat. An axial sliding block 33 is positioned in the groove to squeeze the outer ring of the bearing, causing axial sliding, thereby driving the sun helical gear shaft 7 to produce a micro-axial displacement. A corrugated spring is positioned at the top of the axial sliding block 33 to dynamically compensate for axial movement caused by sudden torque changes or tooth surface wear. The axial thrust of the sun helical gear shaft 7 causes the two sets of planetary gears with opposite spiral angles to produce angular displacements of equal size and opposite direction, so that there is always a planetary gear set that fits the tooth surface of the sun helical gear shaft 7 during the alternating process of the reducer torque output direction, thereby achieving zero return clearance during the three-stage reduction transmission process.

[0069] In this embodiment, a multi-stage composite backlash elimination mechanism achieves high-rigidity transmission for the joint reducer, achieving a total transmission ratio of 1:5 to 1:500, meeting the requirements of most robot joints. The first and second stage reduction transmissions utilize electrical backlash elimination to dynamically adjust motor output torque and actively eliminate gear return clearance. The third stage reduction transmission utilizes mechanical backlash elimination, leveraging the helical gear meshing structure to passively eliminate gear return clearance.

[0070] Example 2

[0071] In another typical embodiment of the present invention, Figure 1-Figure 7 As shown, a working method of a robot joint reducer device is given, and the robot joint reducer device in Example 1 is constructed.

[0072] A method for operating a robot joint reducer device, comprising:

[0073] The follower cover 22 is connected to the external actuator;

[0074] During movement, one driving element outputs a positive driving torque as the main driving element, and the other driving element outputs a reverse torque as the auxiliary driving element, which is smaller than the positive driving torque, to keep the reverse tooth surfaces of the first-stage driven bevel gear meshing with the first-stage driving bevel gear, and at the same time ensure the reverse tooth surfaces of the second-stage driving gear and the second-stage driven gear meshing, thus eliminating the return clearance between the first-stage reduction transmission and the second-stage reduction transmission;

[0075] The sun helical gear shaft 7 generates axial displacement, driving the two sets of planetary gear sets with opposite rotation directions to rotate at opposite angles, so that the sun helical gears on the sun helical gear shaft 7 are respectively in close contact with the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the return clearance of the three-stage reduction transmission;

[0076] The driving element drives the follower cover 22 to output power after being sequentially driven by the first-stage reduction transmission, the second-stage reduction transmission and the third-stage reduction transmission.

[0077] By adjusting the preload force of the axial elastic mechanism, the sun helical gear shaft 7 can simultaneously engage with the opposite tooth surfaces of the two sets of planetary gear sets. The sun helical gear shaft 7 in the reducer applies axial preload force through the corrugated spring. Combined with the adjustable gap characteristics of the tapered roller bearing, it can dynamically compensate for the expansion of the gap caused by tooth surface wear, thereby improving the working stability of the robot joint reducer.

[0078] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A robot joint reducer device, characterized in that: include: The three-stage reduction transmission adopts a helical planetary gear structure. Two sets of planetary gears with opposite rotation directions are installed on the planet carrier, which mesh with the sun helical gear shaft respectively. The end of the sun helical gear shaft is equipped with an axial elastic mechanism to apply axial elastic preload to the sun helical gear shaft to eliminate the return clearance of the three-stage reduction transmission. The planet carrier is connected to a follower cover as the output end. A two-stage reduction transmission, comprising a secondary driven gear and a secondary driving gear. The secondary driven gear is mounted on the sun helical gear shaft and rotates at a constant angular velocity. The two secondary driving gears are respectively engaged with the secondary driven gears. The first-stage reduction transmission is equipped with two groups of matched second-stage driving gears. Each first-stage reduction transmission group includes a meshing first-stage driving bevel gear and a first-stage driven bevel gear. The first-stage driven bevel gear and the second-stage driving gear rotate coaxially with each other at the same angular velocity. The first-stage driving bevel gear is connected to the driving element. The two driving elements apply reverse torque to the second-stage driven gear through the second-stage driving gear, eliminating the return clearance between the first-stage reduction transmission and the second-stage reduction transmission. The two secondary driving gears are symmetrically arranged relative to the axis of the sun helical gear shaft; The axial elastic mechanism includes an axial sliding block, a wave spring and a pre-tightening nut cover. The sun helical gear shaft passes through a tapered roller bearing and a matching end cover. The axial sliding block abuts against an outer ring of the tapered roller bearing. The pre-tightening nut cover matches the end cover. The wave spring abuts between the pre-tightening nut cover and the axial sliding block.

2. The robot joint reducer device according to claim 1, characterized in that: The first-stage active bevel gear is a hypoid spiral bevel gear shaft, the first-stage driven bevel gear is an end face spiral bevel gear, and the driving element is located outside one end of the second-stage driven gear and is distributed toward the axis of the sun helical gear shaft.

3. The robot joint reducer device according to claim 2, characterized in that: The axes of the first-stage driving bevel gears connected to the two driving elements are parallel to each other, and the axes of the first-stage driving bevel gear and the first-stage driven bevel gear in the same group are perpendicular to each other.

4. The robot joint reducer device according to claim 1, wherein: The three-stage reduction transmission also includes an outer ring gear that cooperates with the planetary gear set. The outer ring gear is connected to an end cover. One end of the sun helical gear shaft rotates to cooperate with the end cover, and the other end rotates to cooperate with the follower cover. An axial movement allowance is left between the sun helical gear shaft and the planetary gear set.

5. The robot joint reducer device according to claim 1, wherein: The planet carrier includes a transmission shaft, a planetary gear set is mounted on the transmission shaft, and the planetary gear set meshes with the outer ring gear.

6. The robot joint reducer device according to claim 5, characterized in that: The planet carrier also includes a planet carrier 1 and a planet carrier 2 axially spaced apart along the sun bevel gear shaft, wherein one set of planetary gear sets is located between the planet carrier 1 and the planet carrier 2, and the other set of planetary gear sets is located between the planet carrier 2 and the follower cover.

7. A method for operating a robot joint reducer device, comprising: constructing a robot joint reducer device as claimed in any one of claims 1 to 6, characterized in that: include: The follower cover is connected to the external actuator; During movement, one driving element outputs a positive driving torque as the main driving element, and the other driving element outputs a reverse torque as the auxiliary driving element, which is smaller than the positive driving torque, to keep the reverse tooth surfaces of the first-stage driven bevel gear meshing with the first-stage driving bevel gear, and at the same time ensure the reverse tooth surfaces of the second-stage driving gear and the second-stage driven gear meshing, thus eliminating the return clearance between the first-stage reduction transmission and the second-stage reduction transmission; The sun helical gear shaft produces axial displacement, driving the two sets of planetary gear sets with opposite rotation directions to rotate at opposite angles, so that the sun helical gears on the sun helical gear shaft are respectively close to the opposite tooth surfaces of the two sets of planetary gear sets, eliminating the return clearance of the three-stage reduction transmission; The driving element drives the follower cover to output power after passing through the first-stage reduction transmission, the second-stage reduction transmission and the third-stage reduction transmission in sequence.

8. The operating method of the robot joint reducer device according to claim 7, characterized in that: The preload force of the axial elastic mechanism is adjusted so that the sun helical gear shaft can engage with the opposite tooth surfaces of the two sets of planetary gear sets at the same time.

Images