A backlash-free support structure for a composite planetary gear reducer and a composite planetary reducer.

Abstract

This invention discloses a backlash-free support structure for a composite planetary gear reducer and a composite planetary reducer. The support structure includes a planetary pin shaft passing through the composite planetary gear and rotating with the composite planetary gear via bearings. The axial ends of the planetary pin shaft are supported by a first pin seat and a second pin seat, respectively. The planetary carrier is provided with guide cavities that respectively accommodate the first pin seat and the second pin seat. The planetary carrier is correspondingly provided with a first elastic preload unit and a second elastic preload unit for correspondingly pushing the first pin seat and the second pin seat to move radially. The first pin seat and the second pin seat are respectively provided with bearing surfaces. The planetary carrier is provided with bearing steps that mate with the bearing surfaces. Under no-load, light-load, or zero-torque conditions, the elastic preload units can reduce or eliminate the backlash of the internal meshing pair teeth. After the working load increases, the main radial load is transmitted through the bearing steps, which can balance low backlash, high rigidity, long-term wear compensation capability, and impact resistance reliability.

Description

Technical Field

[0001] This invention relates to the field of precision planetary reducer technology, specifically to a backlash-free support structure for a composite planetary gear reducer and a composite planetary reducer. Background Technology

[0002] Planetary gear reducers, with their advantages of compact structure, high load capacity, wide transmission ratio range, and coaxial input / output, are widely used in robot joints, precision servo drives, and industrial automation equipment. For applications requiring high reduction ratios and high torque density, composite planetary transmission structures such as the 3K type and Wolfrom type can achieve large transmission ratios within a small axial and radial space, making them suitable for robot joints and precision actuators.

[0003] In gear transmissions, due to factors such as gear machining errors, heat treatment deformation, assembly errors, bearing clearance, elastic deformation of support components, and lubricating oil film, meshing pairs typically require a certain amount of tooth flank clearance to ensure smooth gear meshing and prevent excessive meshing, overheating, accelerated wear, or jamming. This tooth flank clearance has a relatively small impact in unidirectional stable transmissions, but under low-speed micro-motion, reciprocating oscillation, torque zero-crossing, and reversing conditions, it manifests as return error, idle stroke, impact noise, and transmission error fluctuations. For robot joints, return error reduces end-effector positioning accuracy, force control stability, and motion smoothness.

[0004] In 3K or Wolfrom type compound planetary reducers, the compound planetary gears typically form internal meshing pairs with the fixed internal gear ring and the output internal gear ring at different axial positions. Due to the large overall transmission ratio of this type of structure, the transmission error and return error at the output end are highly sensitive to the backlash of the internal meshing pairs on both sides. Simply increasing the machining accuracy of the gears, internal gear ring, planetary carrier, and bearing bores to reduce backlash would significantly increase manufacturing costs and assembly difficulty. Furthermore, with long-term use causing wear on the tooth surfaces, bearings, and support interfaces, the initially small backlash may gradually increase, leading to a decrease in reducer accuracy.

[0005] In existing technologies, there are solutions to improve backlash or load distribution using integral elastic planetary carriers, elastic pins, floating planetary gears, or elastic offset components. Integral elastic planetary carriers can change the position of the planetary gears through radial expansion and contraction, but the overall elastic structure reduces the local stiffness of the planetary carrier. When the planetary carrier needs to undertake support, positioning, or output-related functions, excessive elastic deformation may affect transmission stability and heavy-load accuracy. Elastic pins can improve load sharing among multiple planetary gears, but their main function is usually load distribution and shock absorption, with limited ability to compensate for backlash in the internal meshing pairs under no-load, light-load, and zero-torque conditions.

[0006] Some existing solutions employ a floating planetary shaft body to eliminate backlash. For example, radial slots are provided on the planet carrier, and a flat structure is provided at the end of the planetary shaft, allowing the end of the planetary shaft to slide and be limited in rotation within the radial slots. Then, a radial force is directly applied to the planetary shaft through an elastic component, bringing the planet gears closer to the sun gear or the internal ring gear. Furthermore, there are also solutions that attempt to simultaneously clamp different meshing pairs by applying radial forces in opposite directions at both ends to create an overturning moment.

[0007] In the aforementioned floating planetary shaft structures, the ends of the planetary shaft often simultaneously perform multiple functions, including support, guidance, rotation limitation, force bearing, and displacement compensation. This can easily lead to problems such as complex machining, reduced end strength, and difficulty in controlling assembly consistency. When the elastic components act directly on the planetary shaft, spring load, guide friction, and gear meshing reaction force can easily couple together. If the attitude of the compound planetary gear is changed by overturning moment to accommodate different meshing pairs, tooth surface contact deviation may be introduced, affecting tooth surface load distribution and service life.

[0008] For practical applications such as robot joints, reducers not only need to have minimal backlash under no-load or light-load conditions, but also need to maintain high support stiffness and structural reliability under rated load, impact load, and frequent reversing conditions. If the elastic component bears the main load for a long time under heavy load, fatigue, insufficient stiffness, hysteresis, and wear of the elastic component will affect the transmission accuracy and lifespan.

[0009] Therefore, it is necessary to provide a new support structure so that the elastic element is mainly used for low-load backlash elimination, torque zero-crossing state compensation and long-term wear compensation, so that the rigid structure can bear the main radial load under loading conditions, and reduce the structural problems caused by the planetary shaft body directly acting as an irregular sliding element and directly being subjected to the action of the elastic element. Summary of the Invention

[0010] Technical objective: To address the problems of tooth backlash in existing composite planetary reducers under no-load, light-load, commutation, and zero-torque conditions, and the insufficient rigidity and reliability of existing elastic backlash elimination structures under heavy-load conditions, this invention discloses a backlash elimination support structure for a composite planetary gear reducer and a composite planetary reducer.

[0011] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution: A backlash-free support structure for a composite planetary gear in a speed reducer is provided, mounted on the planetary carrier of the speed reducer for supporting the composite planetary gear. It includes a planetary pin that passes through the composite planetary gear and rotates with it via bearings. The axial ends of the planetary pin are supported by a first pin seat and a second pin seat, respectively. The planetary carrier has guide cavities that respectively accommodate the first and second pin seats. The first and second pin seats slide in the guide cavities along the radial direction of the composite planetary gear. The planetary carrier is correspondingly provided with a first elastic preload unit and a second elastic preload unit for correspondingly pushing the first and second pin seats to move radially. The first and second pin seats are respectively provided with bearing surfaces for cooperating with the corresponding elastic preload units. The planetary carrier is provided with a bearing step for providing rigid support to the composite planetary gear, and the bearing step cooperates with the bearing surface.

[0012] Preferably, the first elastic preload unit of the present invention acts directly or through a corresponding force transmission member on the force-bearing part of the first pin seat, and the second elastic preload unit acts directly or through a corresponding force transmission member on the force-bearing part of the second pin seat. The bearing surface is located on the lower surface of the force-bearing part. Under the elastic force of the first elastic preload unit and the second elastic preload unit, both the first pin seat and the second pin seat have a tendency to move radially outward towards the planetary carrier.

[0013] Preferably, in the present invention, when the reducer is unloaded, lightly loaded, or under zero torque conditions, the first elastic preload unit and the second elastic preload unit push the corresponding pin seat to move radially outward, so that the compound planetary gear is close to the corresponding internal gear ring, thereby reducing or eliminating the tooth backlash of the corresponding internal meshing pair; after the working load of the reducer increases, the first pin seat and the second pin seat retract radially under the action of the corresponding tooth surface reaction force, so that the bearing surface contacts the corresponding bearing step, and the working load is at least partially transmitted to the planet carrier through the bearing surface and the bearing step.

[0014] Preferably, in the present invention, a pipe gap is formed between the bearing surface and the corresponding bearing step in the unloaded state of the reducer, and the pipe gap is less than or equal to the maximum radial elastic compensation stroke of the corresponding pin seat to the composite planetary gear.

[0015] Preferably, the guide cavity of the present invention includes a lateral guide surface extending radially along the planetary carrier, and the first pin seat and the second pin seat respectively include a sliding guide surface that cooperates with the lateral guide surface to restrict the corresponding pin seat from moving mainly radially along the planetary carrier and to restrict the corresponding pin seat from rotating circumferentially.

[0016] Preferably, the first elastic preload unit and the second elastic preload unit of the present invention have different equivalent stiffnesses. The one with greater stiffness in the first elastic preload unit and the other with less stiffness is the main preload unit, and the other is the follower preload unit. The first elastic preload unit and the second elastic preload unit absorb the asynchronous displacement of the first pin seat and the second pin seat caused by assembly error, tooth back clearance difference, guide friction difference or load distribution difference.

[0017] Preferably, the planetary pin of the present invention is a cylindrical pin or a pin with a cylindrical support section, and the first pin seat and the second pin seat are respectively provided with pin holes for supporting the planetary pin.

[0018] Preferably, the first elastic preload unit and the second elastic preload unit of the present invention are both compression springs. The elastic force direction of the compression spring is radially outward towards the planetary carrier. The first elastic preload unit and the second elastic preload unit are respectively installed in the spring mounting cavity. The spring mounting cavity is disposed in the planetary carrier or in the spring seat fixedly connected to the planetary carrier. The spring mounting cavity is used to limit the offset of the corresponding elastic preload unit except in the extension direction.

[0019] Preferably, the planetary carrier of the present invention is provided with an axial limiting member at a position corresponding to the end of the planetary pin shaft. The axial limiting member is used to restrict the first pin seat, the second pin seat and the planetary pin shaft from axially disengaging. A working gap is provided between the axial limiting member and the corresponding pin seat.

[0020] This invention discloses a composite planetary reducer, including the aforementioned support structure. The composite planetary reducer is a 3K type composite planetary reducer, a Wolford type composite planetary reducer, or a multi-internal meshing composite planetary transmission device with at least two internal meshing pairs.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention drives the two ends of the planetary pin shaft to generate a small displacement radially outward by the first pin seat and the second pin seat respectively, so that the compound planetary gear is close to the corresponding internal gear ring at the internal meshing position on both sides, thereby reducing the backlash error caused by tooth backlash under no-load, light-load and zero-torque conditions.

[0022] 2. This invention provides a bearing surface on the pin seat and a bearing step on the planetary carrier. When the load increases, the pin seat retracts and contacts the bearing step, and the main load is transmitted through a rigid contact path, improving the support stiffness under heavy load conditions and the reliability of the robot joint under impact conditions.

[0023] 3. In this invention, the bearing step takes over after the working load reaches a certain level, and the elastic preload unit mainly undertakes the functions of low-load backlash elimination, return and wear compensation, thereby reducing the fatigue risk caused by the spring bearing the main working load for a long time.

[0024] 4. Even after long-term minor wear on the gear teeth, bearings, or guide pairs, the elastic preload unit can still push the pin seat to continue to compensate radially outward, keeping the internal meshing pair with a small backlash, which helps to delay the decline in the accuracy of the reducer.

[0025] 5. The present invention uses the guide cavity and the pin seat sliding surface to undertake the guiding function, the elastic preload unit and the force-bearing part to undertake the pushing function, the bearing surface and the bearing step to undertake the heavy load force transmission function, and the axial limiting part to undertake the anti-disengagement function, so that each functional path is clear and easy to manufacture, assemble, debug and maintain.

[0026] 6. The present invention designs the first elastic preload unit and the second elastic preload unit with different equivalent stiffnesses, so that one end has better displacement adaptability while maintaining the outward preload, and can absorb the difference in meshing clearance between the two ends and assembly error. Compared with the conventional method of eliminating clearance through elastic elements, the design of the present invention is beneficial to reducing the risk of slider jamming, friction hysteresis and additional bending of the pin.

[0027] 7. The present invention uses a pin seat as the main radial moving part, which allows the planetary pin shaft to be a cylindrical pin shaft or a pin shaft with a cylindrical support section, reducing the need for setting complex irregular sliding structures at the end of the planetary pin shaft, and is beneficial to improving the pin shaft strength, machining consistency and assembly reliability.

[0028] 8. The present invention can select rectangular linear compression springs, round linear compression springs, disc spring groups, wave springs or combined elastic components according to different space and load requirements. It can also adopt an integrated bearing step, replaceable wear-resistant blocks, adjustable stop blocks or adjusting shims. It is not limited by the structure of the composite planetary gear of the reducer itself, and can be used only by the pin seat and the planetary carrier. It is suitable for composite planetary reducers of different specifications and different working conditions. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for the embodiments are briefly described below. The following drawings are used to illustrate the structural principles of the present invention and do not limit the scope of protection of the present invention.

[0030] Figure 1 This is a cross-sectional view of the overall structure of the present invention applied to a composite planetary reducer; Figure 2 This is a schematic diagram showing the position of the pin seat of the present invention in an unloaded, backlash-free state; Figure 3 This is a schematic diagram showing the position of the pin seat of the present invention in the loaded pipe state; Figure 4 This is a schematic diagram of the pin support using elastic preload units of different stiffness according to the present invention; Figure 5This is a schematic diagram showing the fit between the axial limiting component, the pin seat, and the planetary carrier of the present invention.

[0031] Among them, 1-planetary carrier, 2-planetary pin, 3-composite planetary gear, 4-first internal gear ring, 5-second internal gear ring, 6-first pin seat, 7-second pin seat, 8-guide cavity, 9-guide surface, 10-first elastic preload unit, 11-second elastic preload unit, 12-force transmission component, 13-force receiving part, 14-bearing surface, 15-bearing step, 16-connector gap, 17-spring mounting cavity, 18-axial limiting component, 19-fastener, 20-sliding guide surface, 21-pin hole. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The described embodiments are used to explain the structure, connection relationships, and working process of the present invention, and are not intended to limit the scope of protection of the present invention. Equivalent substitutions, combinations, modifications, and partial improvements made by those skilled in the art based on the disclosure of the present invention should all fall within the scope of protection of the present invention.

[0033] In the description of this invention, with the central axis of the reducer as a reference, the direction away from the central axis of the reducer is defined as the radial outer side, and the direction closer to the central axis of the reducer is defined as the radial inner side. The axial direction refers to the axial direction of the planetary pin 2, and the radial direction refers to the radial direction relative to the central axis of the reducer. Example

[0034] like Figure 1 As shown, this embodiment discloses a backlash-free support structure for a composite planetary gear reducer, mainly applied to a 3K type composite planetary reducer. The composite planetary reducer includes a planet carrier 1, a planetary pin shaft 2, a composite planetary gear 3, a first internal gear ring 4, and a second internal gear ring 5. The composite planetary gear 3 is rotatably mounted on the planetary pin shaft 2 via needle roller bearings or other bearing structures. The composite planetary gear 3 has a first tooth portion that meshes with the first internal gear ring 4 and a second tooth portion that meshes with the second internal gear ring 5 at different axial positions.

[0035] The first internal gear ring 4 can be a fixed internal gear ring, and the second internal gear ring 5 can be an output internal gear ring; alternatively, depending on the specific composite planetary transmission topology, the first internal gear ring 4 and the second internal gear ring 5 can be configured as other functional gear rings. For 3K type or Wolfrom type transmission structures, there is usually a difference in the number of teeth or a difference in the combination of the number of teeth between the first internal gear ring 4 and the second internal gear ring 5, enabling the reducer to achieve a larger overall transmission ratio.

[0036] The planetary pin 2 is supported at both axial ends by a first pin seat 6 and a second pin seat 7, respectively. The first pin seat 6 and the second pin seat 7 are each provided with a pin hole 21, and both ends of the planetary pin 2 are respectively engaged with the corresponding pin holes 21. The planetary pin 2 can be interference-fitted with the pin seat, or it can be clearance-fitted and then limited by an axial limiting member or other retaining structure. Preferably, the planetary pin 2 is a cylindrical pin or a pin with a cylindrical support section to ensure the support strength and machining consistency of the planetary pin 2.

[0037] This invention includes a first elastic preload unit 10 and a second elastic preload unit 11 for driving the first pin seat 6 and the second pin seat 7 to move radially. The planetary carrier 1 is provided with guide cavities 8 for accommodating the first pin seat 6 and the second pin seat 7, respectively. The guide cavities 8 can be located on the planetary carrier body, or on a support member, end cap, partial insert, or separate disk fixedly connected to the planetary carrier. The guide cavity 8 has a predetermined length in the radial direction, allowing the pin seat to move in a small radial stroke. Guide surfaces 9 are formed on both sides of the guide cavity 8, and sliding guide surfaces 20 are formed on the outer sides of the first pin seat 6 and the second pin seat 7. The guide surfaces 9 and the sliding guide surfaces 20 cooperate to restrict the radial movement of the pin seat and to limit significant rotation of the pin seat around the axis of the planetary pin shaft 2. The guide surface 9 can be a plane, a dovetail surface, a T-shaped guide surface, a circular arc guide surface, or other guide structures that can restrict the degree of freedom of the pin seat's movement.

[0038] Both the first pin seat 6 and the second pin seat 7 serve as radial position adjustment components for the planetary pin shaft 2. During the backlash elimination process, the first elastic preload unit 10 and the second elastic preload unit 11 cooperate with their corresponding pin seats. The pin seats move within the guide cavity 8, and the planetary pin shaft 2 moves as a whole with the pin seats. The compound planetary gear 3 generates a corresponding small-stroke radial displacement along with the planetary pin shaft 2. This structure allows the planetary pin shaft 2 to primarily undertake rigid support and force transmission functions, reducing the additional functions that the planetary pin shaft 2 itself needs to undertake as a guide sliding component.

[0039] like Figure 2 As shown, in an embodiment of the present invention, the first elastic preload unit 10 is disposed corresponding to the first pin seat 6, and the second elastic preload unit 11 is disposed corresponding to the second pin seat 7. Both the first elastic preload unit 10 and the second elastic preload unit 11 are installed in the spring mounting cavity 17. The spring mounting cavity 17 can be disposed in the planetary carrier 1 body, or it can be disposed in a spring seat, cover plate or partial support member fixedly connected to the planetary carrier 1.

[0040] In this embodiment, the first elastic preload unit 10 and the second elastic preload unit 11 are preferably rectangular wire compression springs. Rectangular wire compression springs have high force density and are suitable for short stroke, high preload, and space-constrained applications. The spring mounting cavity 17 is a blind hole or semi-closed cavity, used to limit the lateral displacement of the compression spring and ensure that the spring's line of action is close to the force center of the pin seat.

[0041] The first elastic preload unit 10 acts on the force-receiving part 13 of the first pin seat 6 via the force transmission member 12, and the second elastic preload unit 11 acts on the force-receiving part 13 of the second pin seat 7 via the force transmission member 12. The force-receiving part 13 is preferably located radially outward of the pin seat, and is a force-receiving shoulder integrally formed with the pin seat body, with a bearing surface 14 formed on its lower surface. The force transmission member 12 is preferably a planar hardened pressure head, with one side contacting the end face of the compression spring and the other side contacting the plane of the force-receiving part 13 of the pin seat.

[0042] The function of the force transmission component 12 is to transmit the local force at the end of the spring to the force-bearing part 13 of the pin seat more evenly, while reducing the wear caused by the direct friction between the spring end ring and the pin seat. The force transmission component 12 can have a small movable clearance within the spring mounting cavity 17 to facilitate assembly and leveling of the spring end face. For robot joint applications with frequent impacts, the force transmission component 12 and the force-bearing part 13 adopt a planar contact, which helps to increase the bearing area, reduce local contact stress, and improve the structural stability after multiple impacts.

[0043] In other embodiments, the force transmission element 12 may be omitted, and the elastic preload unit may act directly on the force-bearing part 13 of the pin seat. In this case, the spring end is preferably a ground end, and the force-bearing part 13 may be hardened, nitrided, coated, or fitted with wear-resistant pads to reduce wear; or the force-bearing part 13 may be acted on by a spring cap, plunger, pad, or compliant intermediate element.

[0044] like Figure 3 As shown, the planetary carrier 1 is provided with a bearing step 15 that mates with the bearing surface 14. Besides abutting against the compression spring for force transmission, the bearing surface 14 also includes an area opposite to the bearing step 15. Under no-load or light-load conditions, the elastic preload unit pushes the pin seat to move radially outward, creating a pipe gap 16 between the bearing surface 14 and the bearing step 15. This pipe gap 16 corresponds to the effective stroke of the pin seat retracting from the gap-free position to the rigid bearing position.

[0045] The force-bearing part 13 can be a shoulder, step, groove bottom, embedded force-bearing block, or force-bearing plate connected to the pin seat on the radially outer side of the pin seat. It is only necessary to form a bearing surface 14 on the lower surface.

[0046] When the reducer is in a no-load, light-load, low-speed micro-motion, or torque-crossing state, the first elastic preload unit 10 and the second elastic preload unit 11 push the first pin seat 6 and the second pin seat 7 radially outward, respectively. The first pin seat 6 and the second pin seat 7 drive the planetary pin shaft 2 and the compound planetary gear 3 to move radially outward with a small stroke, so that the first tooth and the second tooth of the compound planetary gear 3 are close to the first internal gear ring 4 and the second internal gear ring 5, respectively, thereby reducing or eliminating the backlash of the internal meshing pair teeth on both sides.

[0047] When the reducer is subjected to a large working load, the compound planetary gear 3 is subjected to the reaction force of the internal meshing pair tooth surface. The tooth surface reaction force is transmitted through the compound planetary gear 3, bearings, and planetary pins 2 to the first pin seat 6 and the second pin seat 7, causing the pin seats to retract radially. When the bearing surface 14 contacts the bearing step 15, the main radial load is transmitted through the bearing surface 14, the bearing step 15, and the planetary carrier 1 body. At this time, the first elastic preload unit 10 and the second elastic preload unit 11 maintain a certain amount of compression, mainly undertaking the functions of return, preload retention, and wear compensation. This structure can achieve backlash elimination in the low-load stage and achieve rigid support in the high-load stage.

[0048] The bearing step 15 can be directly formed from the planetary carrier 1, or it can be formed from wear-resistant blocks or adjusting shims embedded in the planetary carrier 1. The contact surface of the bearing step 15 is preferably hardened, or a replaceable wear-resistant block is provided to improve wear resistance under long-term impact and repeated pipe connection conditions. The edges of the bearing step 15 and the bearing surface 14 can be provided with small chamfers or rounded corners to avoid sharp corner impacts on the pipe connection.

[0049] The position of the bearing step 15 can be configured according to the design objectives. A more conservative configuration is that when the pin seat bearing surface 14 contacts the bearing step 15, the pin seat is at or near its theoretical bearing position to avoid excessive outward offset of the compound planetary gear 3 under heavy load, which could lead to overly tight meshing. For applications requiring further reduction of the unloading return stroke, the bearing step 15 can be configured to retain a small radial outward offset compensation amount when the pin seat is in the pipe-connected state. This outward offset compensation amount is preferably less than a portion of the pin seat's maximum elastic compensation stroke and can be adjusted by adjusting shims, wear block thickness, or grinding methods.

[0050] like Figure 4 As shown, the first elastic preload unit 10 and the second elastic preload unit 11 of the present invention can be configured with different equivalent stiffnesses. Preferably, one end of the elastic preload unit has higher stiffness to establish a more dominant radial support position; the other end of the elastic preload unit has lower stiffness to absorb the difference in actual backlash displacement at both ends while maintaining radial outward preload. The equivalent stiffness of the first elastic preload unit 10 and the second elastic preload unit 11 can be adjusted by the spring wire diameter, cross-sectional shape, effective number of turns, material, preload amount, stacking method, or combination of elastic elements. The difference may come from the machining error of the first internal gear ring 4 and the second internal gear ring 5, the tooth error on both sides of the composite planetary gear 3, the position error of the guide cavities 8 at both ends of the planetary carrier 1, the friction difference of the guide pair, or the assembly height difference.

[0051] Through the above-mentioned different stiffness designs, both the first pin seat 6 and the second pin seat 7 can provide backlash-free preload to the radially outward side, while reducing the risk of jamming caused by complete rigid synchronization at both ends. The side with lower stiffness can provide following compensation within a small displacement range, making the planetary pin shaft 2 less prone to additional bending, and the pin seat less prone to wobble and seizing within the guide cavity 8.

[0052] like Figure 5 As shown, the planetary carrier 1 end face is also provided with an axial limiting member 18. The axial limiting member 18 can be an end cover, pressure plate, retaining ring, clamping plate or other limiting structure connected to the planetary carrier 1.

[0053] The axial limiting member 18 is fixed to the planetary carrier 1 by fasteners 19, and is used to prevent the first pin seat 6, the second pin seat 7, and the planetary pin shaft 2 from axially disengaging. A small working clearance is maintained between the axial limiting member 18 and the pin seat to prevent the pin seat from being excessively compressed by the axial limiting member 18 during radial movement. The axial limiting member 18 mainly performs the function of axial retention, and the radial guidance of the pin seat is mainly provided by the guide cavity 8, the guide surface 9, and the sliding guide surface 20.

[0054] The assembly process in this embodiment may include the following steps: First, the first pin seat 6 and the second pin seat 7 are respectively installed into the corresponding guide cavities 8 of the planetary carrier 1, so that the sliding guide surface 20 of the pin seat cooperates with the guide surface 9.

[0055] Next, the planetary pin 2 is inserted into the pin hole 21 of the first pin seat 6 and the second pin seat 7, and the composite planetary gear 3 and its bearing are installed on the planetary pin 2.

[0056] Next, the first elastic preload unit 10 and the second elastic preload unit 11 are respectively installed into the corresponding spring mounting cavity 17. The force transmission component 12 is installed as needed, so that the force transmission component 12 abuts against the force receiving part 13 of the pin seat. The force transmission component 12 can be integrally formed with the pin seat, or it can be installed as an independent part between the spring and the pin seat.

[0057] Then, the axial limiting member 18 is installed and fixed by the fastener 19, so that the pin seat and planetary pin 2 are restricted to the predetermined axial position.

[0058] Finally, check whether the small stroke movement of the pin seat in the radial direction is smooth, and make adjustments according to the actual tooth backlash, spring preload, and bearing step connector position.

[0059] In this embodiment, both the first elastic preload unit 10 and the second elastic preload unit 11 apply force radially outward, the purpose of which is to make the teeth on both sides of the composite planetary gear 3 simultaneously approach the corresponding internal gear ring. This force application method is suitable for 3K type, Wolfrom type, or other composite planetary transmission structures where the internal meshing pairs on both sides have a significant impact on the output backlash. Example

[0060] This embodiment has the same main structure as Embodiment 1, the difference being that the specific form of the elastic preload unit is different.

[0061] In this embodiment, the first elastic preload unit 10 and the second elastic preload unit 11 can be disc springs, wave springs, circular compression springs, mold springs or other elastic elements that can provide radial outward preload in a small space. The elastic preload unit can be composed of a single spring or multiple springs connected in parallel, series or combination to obtain different force-displacement curves.

[0062] Disc springs are suitable for applications with short installation heights and high preload; wave springs are suitable for applications with small axial heights and medium preload; and round wire compression springs are suitable for applications requiring prototype verification, low-cost manufacturing, or where there is ample spring space.

[0063] When a disc spring assembly is used, the disc spring assembly is preferably disposed in the spring mounting cavity 17, and the elastic force is stably transmitted to the pin seat force receiving part 13 through the planar force transmission member 12. When a wave spring is used, the wave spring is preferably provided with a suitable radial guide structure to avoid radial displacement of the wave spring during operation.

[0064] This embodiment can also achieve the functions of empty-load gap elimination and loaded pipe connection. Example

[0065] This embodiment has the same main structure as Embodiment 1, except that the connecting pipe position of the bearing step 15 has an adjustable structure.

[0066] In this embodiment, an adjusting shim, a replaceable wear-resistant block 21, or an adjustable stop block are provided at the bearing step 15. By changing the thickness of the adjusting shim, the height of the wear-resistant block, or the position of the adjustable stop block, the pipe gap 16 can be adjusted, thereby changing the stroke of the pin seat from the gap-free position to the rigid bearing position.

[0067] When a more conservative meshing condition is required, the bearing step 15 can be adjusted so that the pin seat is close to the theoretical bearing position when it is connected to the nozzle; when faster backlash reduction is required after unloading, the bearing step 15 can be adjusted so that the pin seat retains a small radial outward offset compensation amount when it is connected to the nozzle. This adjustable structure is beneficial for adjustment according to different gear precision, assembly conditions, lubrication conditions and target backlash. Example

[0068] This embodiment has the same main structure as Embodiment 1, the difference being the pin seat guide structure.

[0069] In this embodiment, the guide cavity 8 can adopt a rectangular guide window, a dovetail groove guide, a T-groove guide, an arc surface guide, or a combination of guide structures. As long as it can limit the pin seat to move in a small stroke mainly in the radial direction in the planet carrier 1, and limit the pin seat from significant circumferential rotation or swaying, it can be used as the guide form of the present invention.

[0070] The sliding guide surface 20 of the pin seat can be hardened, plated, coated with a low-friction coating, or fitted with a wear-resistant liner to reduce static friction and hysteresis. The fit clearance between the guide cavity 8 and the pin seat should ensure that the pin seat can smoothly return to its original position under spring preload, while avoiding excessive clearance that could cause pin seat wobble and concentrated load on the pin hole. Example

[0071] This embodiment discloses a composite planetary reducer using the above-mentioned support structure. The composite planetary reducer can be a 3K type, a Wolford type, or other composite planetary transmission device with two or more internal meshing pairs and suitable for backlash compensation through changes in the radial position of the planetary pin seat.

[0072] In this embodiment, the composite planetary reducer includes an input sun gear, a planet carrier 1, multiple planetary pins 2, multiple composite planetary gears 3, a first internal gear ring 4, and a second internal gear ring 5. The multiple composite planetary gears 3 are evenly distributed circumferentially, and each composite planetary gear 3 is supported by a corresponding planetary pin 2. Each planetary pin 2 has a first pin seat 6 and a second pin seat 7 at both ends. Each pin seat is preloaded radially outward by a corresponding elastic preload unit, and a loading connection is achieved through a corresponding bearing step 15.

[0073] When the input sun gear drives the compound planet gear 3, the compound planet gear 3 meshes with the first internal gear ring 4 and the second internal gear ring 5, respectively. Under no-load or low-load conditions, the elastic preload unit of each planetary position pushes the corresponding pin seat to move radially outward, so that multiple compound planet gears 3 are close to the corresponding internal gear rings, reducing the backlash of the internal meshing pair. After loading, each pin seat retracts according to the actual load and contacts the bearing step 15, so that the main load is borne by the rigid structure of the planet carrier 1.

[0074] Because each planetary position has an independent elastic preload and rigid connecting pipe structure, each planetary position can be slightly compensated within the range of manufacturing and assembly errors, which helps to reduce the overall return error and improve the long-term accuracy maintenance capability of the reducer.

[0075] The above embodiments can be combined with each other, and as long as the combination does not violate the basic technical concept of the present invention, they all fall within the protection scope of the present invention.

[0076] The above description is merely a preferred embodiment of the present invention, used to illustrate the technical principles and structural implementation of the present invention. For those skilled in the art, without departing from the concept of the present invention, various improvements and modifications can be made to the specific layout of the elastic preload unit, pin-supported guide structure, bearing step, force transmission component, axial limiting component, and composite planetary reducer; all such improvements and modifications should be considered within the scope of protection of the present invention.

Claims

1. A backlash-free support structure for a composite planetary gear in a speed reducer, which is mounted on the planet carrier (1) of the speed reducer to support the composite planetary gear (3), characterized in that: The system includes a planetary pin (2) that passes through the composite planetary gear (3) and rotates with the composite planetary gear (3) through a bearing. The axial ends of the planetary pin (2) are supported by a first pin seat (6) and a second pin seat (7), respectively. The planet carrier (1) is provided with guide cavities (8) that respectively accommodate the first pin seat (6) and the second pin seat (7). The first pin seat (6) and the second pin seat (7) slide in the guide cavity (8) along the radial direction of the composite planetary gear (3). The planet carrier (1) is provided with a first elastic preload unit (10) and a second elastic preload unit (11) for correspondingly pushing the first pin seat (6) and the second pin seat (7) to move radially. The first pin seat (6) and the second pin seat (7) are respectively provided with bearing surfaces (14) for cooperating with the corresponding elastic preload units. The planet carrier (1) is provided with a bearing step (15) for providing rigid support for the composite planetary gear (3). The bearing step (15) cooperates with the bearing surface (14).

2. A composite planetary wheel anti-backlash support structure for a speed reducer according to claim 1, wherein The first elastic preload unit (10) acts directly or through the corresponding force transmission member (12) on the force-bearing part (13) of the first pin seat (6), and the second elastic preload unit (11) acts directly or through the corresponding force transmission member (12) on the force-bearing part (13) of the second pin seat (7). The bearing surface (14) is located on the lower surface of the force-bearing part (13). Under the elastic force of the first elastic preload unit (10) and the second elastic preload unit (11), both the first pin seat (6) and the second pin seat (7) tend to move radially outward towards the planet carrier (1).

3. The backlash-free support structure for a composite planetary gear in a reducer according to claim 2, characterized in that, When the reducer is unloaded, lightly loaded, or under zero torque conditions, the first elastic preload unit (10) and the second elastic preload unit (11) push the corresponding pin seat to move radially outward, so that the compound planetary gear (3) is close to the corresponding internal gear ring, thereby reducing or eliminating the tooth backlash of the corresponding internal meshing pair; after the reducer working load increases, the first pin seat (6) and the second pin seat (7) retract radially under the action of the corresponding tooth surface reaction force, so that the bearing surface (14) contacts the corresponding bearing step (15), and the working load is at least partially transmitted to the planet carrier (1) through the bearing surface (14) and the bearing step (15).

4. The backlash-free support structure for a composite planetary gear in a reducer according to claim 3, characterized in that, When the bearing surface (14) and the corresponding bearing step (15) are in the no-load state of the reducer, a pipe gap (16) is formed. The pipe gap (16) is less than or equal to the maximum radial elastic compensation stroke of the corresponding pin seat to the compound planetary gear (3).

5. The backlash-free support structure for a composite planetary gear in a reducer according to claim 1, characterized in that, The guide cavity (8) includes a lateral guide surface (9) extending radially along the planet carrier (1), and the first pin seat (6) and the second pin seat (7) respectively include a sliding guide surface (20) that cooperates with the lateral guide surface (9) to restrict the corresponding pin seat from moving mainly radially along the planet carrier (1) and to restrict the corresponding pin seat from rotating circumferentially.

6. The backlash-free support structure for a composite planetary gear in a reducer according to claim 1, characterized in that, The first elastic preload unit (10) and the second elastic preload unit (11) have different equivalent stiffnesses. The one with greater stiffness in the first elastic preload unit (10) and the other with less stiffness is the main preload unit. The first elastic preload unit (10) and the second elastic preload unit (11) absorb the asynchronous displacement of the first pin seat (6) and the second pin seat (7) caused by assembly error, tooth back clearance difference, guide friction difference or load distribution difference.

7. The backlash-free support structure for a composite planetary gear in a reducer according to claim 1, characterized in that, The planetary pin (2) is a cylindrical pin or a pin with a cylindrical support section, and the first pin seat (6) and the second pin seat (7) are respectively provided with pin holes (22) for supporting the planetary pin (2).

8. The backlash-free support structure for a composite planetary gear in a reducer according to claim 1, characterized in that, The first elastic preload unit (10) and the second elastic preload unit (11) are both compression springs. The elastic force of the compression springs is directed radially outward from the planetary carrier (1). The first elastic preload unit (10) and the second elastic preload unit (11) are respectively installed in the spring mounting cavity (17). The spring mounting cavity (17) is located inside the planetary carrier (1) or inside a spring seat that is fixedly connected to the planetary carrier (1). The spring mounting cavity (17) is used to limit the offset of the corresponding elastic preload unit except in the extension direction.

9. The backlash-free support structure for a composite planetary gear in a reducer according to claim 1, characterized in that, The planetary carrier (1) is provided with an axial limiting member (18) at a position corresponding to the end of the planetary pin (2). The axial limiting member (18) is used to restrict the first pin seat (6), the second pin seat (7) and the planetary pin (2) from detaching axially. A working gap is provided between the axial limiting member (18) and the corresponding pin seat.

10. A composite planetary reducer, characterized in that, The composite planetary reducer includes the support structure described in any one of claims 1 to 9, wherein the composite planetary reducer is a 3K type composite planetary reducer, a Wolford type composite planetary reducer, or a multi-internal meshing composite planetary transmission device having at least two internal meshing pairs.

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