Bidirectional elastic anti-backlash structure of high-precision planetary reducer

Abstract

The invention provides a bidirectional elastic anti-backlash structure of a high-precision planetary reducer, which relates to the technical field of planetary reduction structures and comprises a reducer shell, an input sun gear, a planet carrier assembly, a planet gear set and an inner gear ring. The planet carrier assembly is provided with a notch extending in the radial direction. Flat position structures matched with the notches in shape are arranged at the upper end and the lower end of the planet shaft; a first radial spring and a second radial spring are respectively mounted at the upper end and the lower end of the planet shaft; the first radial spring applies radial inward elastic force to the planet shaft, so that the large planet wheel presses the input sun wheel; and the second radial spring applies radial outward elastic force to the planet shaft, so that the small planet wheel tightly presses the inner gear ring. The planetary gear set has the beneficial effects that reverse radial force is applied to the planetary shaft through the first radial spring and the second radial spring, overturning moment is formed, the planetary gear set is driven to press the input sun gear and the inner gear ring at the same time, two meshing backlash can be synchronously eliminated, and the transmission precision can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of planetary reduction structures, in particular to a bidirectional elastic backlash-eliminating structure of a high-precision planetary reducer. Background Art

[0002] Due to machining and assembly precision errors in gears and other components, gears are designed with a certain amount of backlash to ensure smooth meshing. However, this backlash can also cause a certain amount of backlash error during meshing. Insufficient backlash during meshing can lead to accelerated wear on the tooth surfaces, increased transmission resistance, and even outright seizure.

[0003] In order to reduce the return error while ensuring the smoothness of the transmission and the life of the gear, the traditional approach is to improve the accuracy of the gear itself and the accuracy of other structural components of the gearbox. In this way, the side clearance can be reduced during the design, thereby reducing the return error in the transmission, and at the same time, the transmission will not be uneven due to poor accuracy.

[0004] However, this approach will greatly increase the cost of production. At the same time, for occasions requiring extremely high precision, blindly improving the precision of the gear itself is not advisable.

[0005] When the gears are meshing, the friction between the tooth surfaces will slightly reduce the tooth thickness. The reduction in tooth thickness means an increase in tooth backlash, which in turn increases the return error. Therefore, as the planetary gear reducer is used, the accuracy will become increasingly poor.

[0006] To eliminate transmission errors, the first thing to do is to eliminate backlash. However, even with backlash eliminated, the gears still need to mesh smoothly, which requires the center distance of the meshing gears to float to offset errors in processing and assembly.

[0007] At the same time, if you want to continue to eliminate the tooth gap after the tooth surface wears, you need to use external force to make the two gears approach each other.

[0008] Currently, in planetary transmissions, planetary gears are the gears that are most likely to meet the above requirements. Floating the planetary gears and simultaneously applying external force to the planetary gears and sun gears or the planetary gears and ring gears can eliminate the backlash in the transmission.

[0009] The current solution uses an elastic planetary carrier, which can expand or contract, allowing the planetary gears to press against the sun gear or the inner ring gear. Because the planetary carrier is elastic, the center distances between the planetary gears and the ring gear, and between the planetary gears and the sun gear, can be dynamically adjusted based on the real-time meshing state, thus solving the problems of uneven transmission and jamming. However, this solution has the following drawbacks: Disadvantage 1: The existing anti-backlash structure relies on the expansion or contraction of the planet carrier to drive the planet gear to press the sun gear or the inner ring gear. Either the backlash between the planet gear and the sun gear or the backlash between the planet gear and the inner ring gear is eliminated, but not both at the same time.

[0010] Disadvantage 2: As the planet gears wear, they mesh tightly with one gear component, but the backlash between them and the other gear component increases. For example, if the planet gears and sun gear are compressed (i.e., the backlash between them is eliminated), the planet gear axes will move toward the sun gear as the tooth surfaces wear. Although the backlash between the planet gears and sun gear is zero, the backlash between the planet gears and the ring gear increases, leading to increased error. The opposite is true if the planet gears and ring gear are compressed.

[0011] Disadvantage 3: The planetary carrier is an elastic body and is not suitable for planetary reducer structures with planetary carrier output. Because the planetary carrier will deform and lack rigidity, it cannot be used as the output structure of the reducer. Summary of the Invention

[0012] The present invention overcomes the shortcomings of the prior art and provides a bidirectional elastic anti-backlash structure for a high-precision planetary reducer, which helps to improve transmission accuracy and is suitable for high-precision servo transmission scenarios. In order to solve the above technical problems, the present invention is achieved through the following technical solutions: A bidirectional elastic anti-backlash structure of a high-precision planetary reducer, comprising a reducer housing and an input sun gear, a planetary carrier assembly and several planetary gear sets installed in the planetary carrier assembly are provided in the reducer housing, and an inner gear ring is also provided in the reducer housing, characterized in that: the planetary carrier assembly is provided with a radially extending slot; the planetary gear set includes a planetary shaft and a large planetary gear and a small planetary gear of integral design, and the large planetary gear and the small planetary gear can rotate relative to the planetary shaft; the upper and lower ends of the planetary shaft are provided with a flat position structure adapted to the shape of the slot, and the flat position structure can be slidably connected in the slot so that the planetary shaft can slide radially and limit circumferential rotation; the large planetary gear is meshed with the input sun gear, and the small planetary gear is meshed with the inner gear ring; an elastic component is provided on the planetary shaft to press the large planetary gear against the input sun gear and to press the small planetary gear against the inner gear ring to eliminate meshing side clearance.

[0013] Furthermore, the elastic component includes a first radial spring located at the upper end of the planet shaft, and a second radial spring located at the lower end of the planet shaft: the first radial spring applies a radially inward elastic force to the planet shaft, so that the large planet gear presses the input sun gear; the second radial spring applies a radially outward elastic force to the planet shaft, so that the small planet gear presses the inner gear ring; The first radial spring and the second radial spring jointly generate a tilting moment to drive the planetary gear set while eliminating meshing backlash with the input sun gear and the inner ring gear; The first radial spring and the second radial spring are both provided with flat notches, elastic slots and tapered holes; the first radial spring is fixed to the top of the planetary carrier assembly through the tapered hole, and the second radial spring is fixed to the bottom of the planetary carrier assembly through the tapered hole. The shape of the flat notch matches the flat position structure of the planetary shaft, and the flat notch of the first radial spring faces the outside of the planetary carrier, and the flat notch of the second radial spring faces the inside of the planetary carrier.

[0014] Furthermore, the planet carrier assembly is a split rigid structure, including an input end planet carrier and an output end planet carrier arranged above and below, and the input end planet carrier and the output end planet carrier are connected and assembled into a whole by fasteners.

[0015] Furthermore, the extending direction of the slot is consistent with the radial direction of the planetary carrier assembly, and the length of the slot is greater than the flattened structural width of the planetary shaft, so as to allow the planetary shaft to slightly move and deflect in the radial direction.

[0016] Furthermore, before installation, the flat notch pitch diameters of the first radial spring and the second radial spring are different from the theoretical pitch diameter of the planet shaft.

[0017] Furthermore, the large planetary gear and the small planetary gear are mounted on the planetary shaft through roller bearings.

[0018] Furthermore, a sealing cover is provided at the central axis hole of the output end planetary carrier.

[0019] Furthermore, a first bearing is provided between the reducer housing and the input sun gear; a second bearing is provided between the reducer housing and the input-end planet carrier; and a third bearing is provided between the reducer housing and the output-end planet carrier.

[0020] Furthermore, an oil seal is provided at the junction of the reducer housing and the output end planetary carrier.

[0021] Furthermore, a radial limiting boss is provided on the edge of the input-end planet carrier to constrain the assembly position of the output-end planet carrier.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention abandons the structure of unidirectional expansion or compression of the planetary carrier, and applies a reverse radial force to the planetary shaft through the first radial spring and the second radial spring to form an overturning torque, driving the planetary gear set to simultaneously press the input sun gear and the inner ring gear, which can synchronously eliminate the meshing side clearances at the two locations and help improve transmission accuracy; the overall structure is compact and suitable for high-precision servo transmission scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and are used to explain the present invention together with the embodiments of the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a cross-sectional view of the bidirectional elastic anti-backlash structure of the high-precision planetary reducer; Figure 2 It is a three-dimensional structure of bidirectional elastic anti-backlash of high-precision planetary reducer. Figure 1 ; Figure 3 It is a three-dimensional structure of bidirectional elastic anti-backlash of high-precision planetary reducer. Figure 2 ; Figure 4 This is an exploded view of the bidirectional elastic anti-backlash structure of the high-precision planetary reducer; Figure 5 is a schematic diagram of the planet carrier assembly, the planetary gear set, and the first radial spring structure; Figure 6 It is a schematic diagram of the planet carrier assembly, planetary gear set, and second radial spring structure; Figure 7 It is a top view of the planet carrier assembly and planetary gear set; Figure 8 It is an exploded view of the input sun gear, planet carrier assembly, and planetary gear set; Figure 9 It is a structural diagram of the planetary gear set; Figure 10 It is a cross-sectional view of the planetary gear set; Figure 11 It is a schematic diagram of the structure of the planet carrier assembly; Figure 12 This is an exploded view of the planet carrier assembly; Figure 13 is a top view of the first radial spring structure; Figure 14 is a top view of the second radial spring structure.

[0024] In the picture: 1. Reducer housing; 2. Input sun gear; 3. Planet carrier assembly; 301. Notch; 302. Input planet carrier; 3021. Radial limit boss; 303. Output planet carrier; 4. Planetary gear set; 401. Planet shaft; 4011. Flat structure; 402. Large planet gear; 403. Small planet gear; 404. Roller bearing; 5. Internal gear ring; 6. First radial spring; 7. Second radial spring; 8. Flat notch; 9. Elastic slot; 10. Tapered hole; 11. Sealing cover; 12. First bearing; 13. Second bearing; 14. Third bearing; 15. Oil seal. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0026] like Figures 1 to 14 As shown, the present invention requests protection for a bidirectional elastic anti-backlash structure of a high-precision planetary reducer, including a reducer housing 1, an input sun gear 2, a planetary carrier assembly 3, a planetary gear set 4 and an inner ring gear 5; specifically, an accommodating space is formed inside the reducer housing 1, and the inner ring gear 5 is fixedly installed, and is connected to the input sun gear 2 through a first bearing 12, connected to the input end planetary carrier 302 of the planetary carrier assembly 3 through a second bearing 13, and connected to the output end planetary carrier 303 through a third bearing 14. In addition, an oil seal 15 is provided at the joint between the reducer housing 1 and the output end planetary carrier 303 to prevent leakage of lubricating oil.

[0027] In this embodiment, it is a split rigid structure for easy assembly and disassembly, including an input-end planetary carrier 302 and an output-end planetary carrier 303 connected and fixed by fasteners. In this embodiment, the fasteners are bolts; in addition, a radial limiting boss 3021 is provided on the edge of the input-end planetary carrier 302 to limit the assembly position of the output-end planetary carrier 303.

[0028] The planetary gear set 4 includes a planetary shaft 401 , a large planetary gear 402 , a small planetary gear 403 and a roller bearing 404 . The large planetary gear 402 and the small planetary gear 403 are integrally designed and mounted on the planetary shaft 401 via the roller bearing 404 , and can rotate relative to the planetary shaft 401 .

[0029] One of the improvements of this technical solution is that the planetary carrier assembly 3 is provided with a slot 301 in the radial direction, and the extension direction of the slot 301 is consistent with the radial direction. The upper and lower ends of the planetary shaft 401 are provided with a flat structure 4011, which is adapted to the shape of the slot 301 and is slidably connected to limit the circumferential rotation of the planetary shaft 401; wherein, from Figure 7 It can be seen that the length of the slot 301 is greater than the width of the flattened structure 4011 of the planet shaft 401, allowing radial micro-motion and yaw of the planet shaft 401. The large planet gear 402 meshes with the input sun gear 2, and the small planet gear 403 meshes with the inner ring gear 5.

[0030] An elastic component is provided on the planetary shaft 401 to compress the large planetary gear 402 against the input sun gear 2 and the small planetary gear 403 against the inner gear ring 5, thereby eliminating meshing backlash. Specifically, in this embodiment, the elastic component includes a first radial spring 6 located at the upper end of the planetary shaft 401 and a second radial spring 7 located at the lower end of the planetary shaft 401. The first radial spring 6 applies a radially inward elastic force to the planetary shaft 401, compressing the large planetary gear 402 against the input sun gear 2. The second radial spring 7 applies a radially outward elastic force to the planetary shaft 401, compressing the small planetary gear 403 against the inner gear ring 5. Both the first radial spring 6 and the second radial spring 7 are provided with a flat notch 8, an elastic slot 9, and a tapered hole 10. The elastic slot 9 provides good elasticity. The first radial spring 6 is fixed above the input-end planetary carrier 302 through the tapered hole 10, with the flat slot 8 facing the outside of the planetary carrier and cooperating with the flat structure 4011 of the planetary shaft 401, applying a radial inward elastic force to the planetary shaft 401, so that the large planetary gear 402 presses the input sun gear 2; the second radial spring 7 is fixed below the output-end planetary carrier 303 through the tapered hole 10, with the flat slot 8 facing the inside of the planetary carrier and cooperating with the flat structure 4011 of the planetary shaft 401, applying a radial outward elastic force to the planetary shaft 401, so that the small planetary gear 403 presses the inner gear ring 5.

[0031] Before installation, the pitch diameter of the flat notch 8 of the first radial spring 6 and the second radial spring 7 is different from the theoretical pitch diameter of the planet shaft 401. Specifically, the pitch diameter of the flat notch 8 of the first radial spring 6 is smaller than the theoretical pitch diameter of the planet shaft 401, thereby exerting a radially inward thrust. The pitch diameter of the flat notch 8 of the second radial spring 7 is larger than the theoretical pitch diameter of the planet shaft 401, thereby exerting a radially outward thrust. Therefore, after the first radial spring 6 and the first radial spring 6 are installed with the planetary gear, a radially inward force or a radially outward force is applied to the planetary shaft 401. In this way, the planetary gear and the sun gear, as well as the planetary gear and the inner ring gear 5, are tightened, and the tooth clearance is eliminated. Even if the tooth thickness becomes slightly thinner due to wear in later use, this structure can continue to eliminate tooth clearance. By generating a tipping torque after assembly, the driving planetary gear set 4 simultaneously eliminates the meshing side clearance with the input sun gear 2 and the inner ring gear 5.

[0032] Specifically, first radial springs 6 and second radial springs 6 are installed on the upper and lower ends of the planet carrier, respectively. One radial spring is responsible for expanding the planet shaft 401, while the other radial spring is responsible for tightening the planet shaft 401. This ensures that the large planet gear 402 is tightly meshed with the sun gear, and the small planet gear 403 is tightly meshed with the inner ring gear 5. The elastic force of the radial spring is determined by its thickness, so radial springs of different thicknesses can be selected according to actual needs.

[0033] A sealing cover 11 is provided at the central axis hole of the output end planet carrier 303 to prevent foreign matter from entering the interior of the reducer.

[0034] This structure applies a reverse radial force to the planetary shaft 401 through the first radial spring 6 and the second radial spring 7, forming an overturning torque, driving the planetary gear set 4 to simultaneously press the input sun gear 2 and the inner ring gear 5, which can synchronously eliminate the meshing side clearances at the two locations, helping to improve transmission accuracy; the planetary shaft 401 slides with the slot 301 through the flat structure 4011, allowing radial micro-motion and deflection to adapt to position adjustment under the action of spring force; the assembly process is simplified by adopting a split planetary carrier design; the overall structure is compact and suitable for high-precision servo transmission scenarios.

[0035] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bidirectional elastic anti-backlash structure for a high-precision planetary reducer, characterized in that: It includes a reducer housing and an input sun gear, a planetary carrier assembly and several planetary gear sets installed in the planetary carrier assembly are provided in the reducer housing, and an inner ring gear is also provided in the reducer housing, characterized in that: the planetary carrier assembly is provided with a radially extending slot; the planetary gear set includes a planetary shaft and a large planetary gear and a small planetary gear of integral design, and the large planetary gear and the small planetary gear can rotate relative to the planetary shaft; the upper and lower ends of the planetary shaft are provided with a flat position structure adapted to the shape of the slot, and the flat position structure can be slidably connected in the slot so that the planetary shaft can slide radially and limit circumferential rotation; the large planetary gear is meshed with the input sun gear, and the small planetary gear is meshed with the inner ring gear; an elastic component is provided on the planetary shaft to press the large planetary gear against the input sun gear and the small planetary gear against the inner ring gear to eliminate the meshing side clearance.

2. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 1 is characterized in that: The elastic component includes a first radial spring located at the upper end of the planet shaft and a second radial spring located at the lower end of the planet shaft: the first radial spring applies a radially inward elastic force to the planet shaft, causing the large planet gear to press against the input sun gear; the second radial spring applies a radially outward elastic force to the planet shaft, causing the small planet gear to press against the inner gear ring; The first radial spring and the second radial spring jointly generate a tilting moment to drive the planetary gear set while eliminating meshing backlash with the input sun gear and the inner ring gear; The first radial spring and the second radial spring are both provided with flat notches, elastic slots and tapered holes; the first radial spring is fixed to the top of the planetary carrier assembly through the tapered hole, and the second radial spring is fixed to the bottom of the planetary carrier assembly through the tapered hole. The shape of the flat notch matches the flat position structure of the planetary shaft, and the flat notch of the first radial spring faces the outside of the planetary carrier, and the flat notch of the second radial spring faces the inside of the planetary carrier.

3. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 2 is characterized in that: The planet carrier assembly is a split rigid structure, comprising an input end planet carrier and an output end planet carrier arranged above and below, and the input end planet carrier and the output end planet carrier are connected and assembled into a whole by fasteners.

4. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 1 is characterized in that: The extending direction of the slot is consistent with the radial direction of the planet carrier assembly, and the length of the slot is greater than the flattened structural width of the planet shaft to allow the planet shaft to slightly move and deflect in the radial direction.

5. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 2 is characterized in that: Before installation, the flat notch pitch diameters of the first radial spring and the second radial spring are different from the theoretical pitch diameter of the planet shaft.

6. The bidirectional elastic backlash eliminating structure of the high-precision planetary reducer according to any one of claims 1 to 5, characterized in that: The large planetary gear and the small planetary gear are mounted on the planetary shaft via roller bearings.

7. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 3 is characterized in that: A sealing cover is provided at the central axis hole of the output end planetary frame.

8. The bidirectional elastic backlash eliminating structure of the high-precision planetary reducer according to claim 7, characterized in that: A first bearing is provided between the reducer housing and the input sun gear; a second bearing is provided between the reducer housing and the input end planet carrier; and a third bearing is provided between the reducer housing and the output end planet carrier.

9. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 8, characterized in that: An oil seal is provided at the junction of the reducer housing and the output end planetary carrier.

10. The bidirectional elastic backlash elimination structure of the high-precision planetary reducer according to claim 3, characterized in that: A radial limiting boss is provided on the edge of the input-end planet carrier to constrain the assembly position of the output-end planet carrier.

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